chore(deps): bump actions/github-script from 7.1.0 to 9.0.0

Bumps [actions/github-script](https://github.com/actions/github-script) from 7.1.0 to 9.0.0. - [Release notes](https://github.com/actions/github-script/releases) - [Commits](https://github.com/actions/github-script/compare/v7.1.0...v9) --- updated-dependencies: - dependency-name: actions/github-script dependency-version: '9' dependency-type: direct:production update-type: version-update:semver-major ... Signed-off-by: dependabot[bot] <support@github.com>
Merge pull request #1890 : storage partition for 8MB, compile node_log out on 4MB
2026-10-19 05:10:13 -05:00 · 2026-09-26 18:01:22 +00:00 · 2026-09-26 12:36:57 -05:00 · 2026-09-16 16:30:28 +00:00 · 2026-09-16 11:53:26 -04:00 · 2026-09-16 11:37:53 -04:00
84 changed files with 11149 additions and 405 deletions
@@ -293,7 +293,7 @@ jobs:
        done

    - name: Update deployment status
-      uses: actions/github-script@f28e40c7f34bde8b3046d885e986cb6290c5673b
+      uses: actions/github-script@3a2844b7e9c422d3c10d287c895573f7108da1b3
      with:
        script: |
          const deployEnv = '${{ needs.pre-deployment.outputs.deploy_env }}';
@@ -344,7 +344,7 @@ jobs:

    - name: Create deployment issue on failure
      if: needs.deploy-production.result == 'failure'
-      uses: actions/github-script@f28e40c7f34bde8b3046d885e986cb6290c5673b
+      uses: actions/github-script@3a2844b7e9c422d3c10d287c895573f7108da1b3
      with:
        script: |
          github.rest.issues.create({
@@ -53,7 +53,9 @@ jobs:
            sdkconfig: sdkconfig.defaults
            partition_table_name: partitions_display.csv
            size_warn_kb: 1100
-            size_limit_kb: 1152
+            # Current 8 MB image is 1163 KiB after USB onboarding. The OTA app
+            # partition is 2048 KiB; retain a 1200 KiB hard gate and warning.
+            size_limit_kb: 1200
            artifact_app: esp32-csi-node.bin
            artifact_pt: partition-table.bin
          - variant: 4mb
@@ -92,12 +94,11 @@ jobs:
          idf.py set-target ${{ matrix.target }}
          idf.py build

-      - name: Build and run host-side ADR-110 unit tests
+      - name: Build and run host-side firmware unit tests
        if: matrix.variant == 'c6-4mb'
        working-directory: firmware/esp32-csi-node/test
        run: |
-          make test_adr110
-          ./test_adr110
+          make host_tests

      - name: Verify binary size budget
        working-directory: firmware/esp32-csi-node
@@ -184,3 +185,22 @@ jobs:
          name: esp32-csi-node-firmware-${{ matrix.variant }}
          path: firmware/esp32-csi-node/release-staging/
          retention-days: 90
+
+  build-c6-idf6:
+    name: Build XIAO C6 external antenna (ESP-IDF 6.0.2)
+    runs-on: ubuntu-latest
+    container:
+      image: espressif/idf:v6.0.2
+    steps:
+      - uses: actions/checkout@11d5960a326750d5838078e36cf38b85af677262
+        with:
+          submodules: recursive
+
+      - name: Build the IDF 6 canary image
+        working-directory: firmware/esp32-csi-node
+        run: |
+          . $IDF_PATH/export.sh
+          idf.py -D SDKCONFIG_DEFAULTS="sdkconfig.defaults;sdkconfig.defaults.esp32c6;sdkconfig.defaults.xiao-external" set-target esp32c6
+          idf.py build
+          test "$(stat -c%s build/esp32-csi-node.bin)" -le $((1152 * 1024))
+          strings build/esp32-csi-node.bin | grep -F "external U.FL"
@@ -460,7 +460,7 @@ jobs:
    - name: Create security issue on critical findings
      continue-on-error: true
      if: needs.sast.result == 'failure' || needs.dependency-scan.result == 'failure'
-      uses: actions/github-script@00f12e3e20659f42342b1c0226afda7f7c042325 # v6
+      uses: actions/github-script@f28e40c7f34bde8b3046d885e986cb6290c5673b # v6
      with:
        script: |
          github.rest.issues.create({
@@ -17,11 +17,16 @@ firmware/esp32-csi-node/sdkconfig.defaults.bak
 firmware/esp32-hello-world/sdkconfig.old

 # Host-built firmware test binaries (compiled from test/*.c, not source)
-firmware/esp32-csi-node/test/test_adr110
-firmware/esp32-csi-node/test/test_vitals
-firmware/esp32-csi-node/test/fuzz_serialize
-firmware/esp32-csi-node/test/fuzz_edge
-firmware/esp32-csi-node/test/fuzz_nvs
+# Compiled host-test and fuzz binaries. The Makefile writes them beside their
+# sources, so they land in a tracked directory. Ignore them by SHAPE rather
+# than by name: every source here carries an extension and no binary does.
+#
+# This replaced a hand-maintained list of five targets, which had gone stale --
+# test_csi_sanitize, test_mmwave_detect and test_thermal were all built by
+# `make host_tests`, ignored by nothing, and got committed by accident.
+firmware/esp32-csi-node/test/test_*
+firmware/esp32-csi-node/test/fuzz_*
+!firmware/esp32-csi-node/test/*.*
 firmware/esp32-csi-node/test/*.exe
 firmware/esp32-csi-node/test/*.obj

@@ -719,6 +719,8 @@ Start with the user, build, and calibration guides; expand for the full referenc
 | [Semantic Primitives — Precision/Recall](docs/integrations/semantic-primitives-metrics.md) | Per-primitive F1 on the held-out paired-capture set: someone-sleeping, possible-distress, room-active, elderly-inactivity-anomaly, meeting, bathroom, fall-risk, bed-exit, no-movement, multi-room. |
 | [Claude Code / Codex Plugin](plugins/ruview/README.md) | The `ruview` plugin + marketplace — skills, `/ruview-*` commands, agents, and the Codex prompt mirror |
 | [Portable harness — `npx @ruvnet/ruview`](harness/ruview/README.md) | MetaHarness-minted, host-portable RuView operator harness — `ruview.*` MCP tools + the MEASURED-vs-CLAIMED honesty guardrail enforced in code ([ADR-182](docs/adr/ADR-182-npx-ruview-harness-via-metaharness.md)). A lighter, multi-host companion to the in-repo plugin. |
+| [CSI Frame Selection — Measured](docs/csi-frame-selection-measured.md) | Which rate gate actually buys cross-node pairing, measured on a nine-node ESP32-C6 fleet as a 2x2 factorial in three Latin-square blocks. Selecting frames by 802.11 `rx_seq` roughly doubled pairing (+31.7 pp) while mesh-time alignment bought +0.5 pp, inside noise. Includes the trade it makes, a prediction that turned out wrong, the limits of the measurement, and `run_arms.py` so the comparison can be re-run rather than taken on trust. |
+| [ESP32-C6 Firmware Runbook](firmware/esp32-csi-node/RUNBOOK.md) | What to run, in what order, and what to check: the three-file build that keeps OTA rollback compiled in, a five-key pre-flash gate, which flash regions OTA can and cannot reach, a single-board diagnostic flash with a revert path, and the tunables whose right value depends on your house rather than on the chip. |
 | [Architecture Decisions](docs/adr/README.md) | 205 ADRs — why each technical choice was made, organized by domain (hardware, signal processing, ML, platform, infrastructure) |
 | [Domain Models](docs/ddd/README.md) | 8 DDD models (RuvSense, Signal Processing, Training Pipeline, Hardware Platform, Sensing Server, WiFi-Mat, CHCI, rvCSI) — bounded contexts, aggregates, domain events, and ubiquitous language |
 | [rvCSI — edge RF sensing runtime](https://github.com/ruvnet/rvcsi) | Rust-first / TypeScript-accessible / hardware-abstracted CSI runtime: multi-source ingestion (incl. real nexmon_csi `.pcap` from a **Raspberry Pi 5** / Pi 4 / Pi 3B+ — CYW43455 / BCM43455c0) → validation → DSP → typed events → RuVector RF memory ([ADR-095](docs/adr/ADR-095-rvcsi-edge-rf-sensing-platform.md), [ADR-096](docs/adr/ADR-096-rvcsi-ffi-crate-layout.md), [domain model](docs/ddd/rvcsi-domain-model.md)). Now its own repo — [`ruvnet/rvcsi`](https://github.com/ruvnet/rvcsi) — vendored here under `vendor/rvcsi`; 9 `rvcsi-*` crates on crates.io, `@ruv/rvcsi` on npm, plus a Claude Code plugin. |
@@ -10,6 +10,35 @@ func main() {
        exit(1)
    }

+    // One connected-link RSSI sample for the Rust adapter. Keep the legacy
+    // no-argument 10 Hz stream below unchanged for Python callers.
+    if CommandLine.arguments.contains("--scan-once") {
+        guard interface.powerOn(),
+              let channel = interface.wlanChannel(),
+              interface.rssiValue() < 0 else {
+            fputs("WiFi is not connected\n", stderr)
+            exit(1)
+        }
+        let sample: [String: Any] = [
+            "ssid": interface.ssid() ?? "",
+            "bssid": interface.bssid() ?? "00:00:00:00:00:00",
+            "channel": channel.channelNumber,
+            "rssi": interface.rssiValue(),
+            "noise": interface.noiseMeasurement(),
+            "timestamp": Date().timeIntervalSince1970,
+            "tx_rate": interface.transmitRate()
+        ]
+        do {
+            let data = try JSONSerialization.data(withJSONObject: sample, options: [.sortedKeys])
+            FileHandle.standardOutput.write(data)
+            FileHandle.standardOutput.write(Data([0x0a]))
+        } catch {
+            fputs("Could not encode WiFi sample: \(error)\n", stderr)
+            exit(1)
+        }
+        return
+    }
+
    // Flush stdout automatically to prevent buffering issues with Python subprocess
    setbuf(stdout, nil)

@@ -0,0 +1,218 @@
+# ADR-323: RTL8721Dx (Realtek AmebaDplus) CSI Wire Protocol
+
+- **Status**: accepted
+- **Date**: 2026-09-15
+- **Deciders**: RuView maintainers
+- **Tags**: realtek, ameba, amebadplus, rtl8721dx, csi, protocol, rust, udp
+
+## Context
+
+Unlike the MediaTek/Qualcomm CSI paths (ADR-266..269), which are simulator-first
+because no supported public vendor interface exports complex CSI, Realtek's
+official Ameba RTOS SDK (`Ameba-AIoT/ameba-rtos`, Apache-2.0) documents and
+exposes a real, callback-driven CSI API for the RTL8721Dx ("AmebaDplus")
+family: `wifi_csi_config()` plus the `RTW_EVENT_CSI_DONE` event delivering a
+`struct rtw_event_csi_report_info` (per-tone signed I/Q, 8-bit or 16-bit
+precision, selectable tone decimation, passive or active/triggered capture).
+This has been confirmed directly against SDK source
+(`component/wifi/api/wifi_api_event.h`) and against the official
+`example/wifi/wifi_csi` example, and validated on real PKM8721DAF-C13-F10
+hardware (build+flash+boot confirmed on branch `feat/rtl8721dx-csi-bringup`).
+
+The RTL8721Dx is a 1x1 WiFi 4 part — single TX/RX chain, not MIMO — so the
+MediaTek/Qualcomm wire format (Tx/Rx dimensioned matrices, chipset chain
+counts) does not fit. The vendor SDK's raw struct is also not a safe host
+wire format as-is: it has no CRC, a C flexible-array-member payload, and
+fields sized for firmware convenience (e.g. a wrapping `u32` microsecond
+timestamp) rather than network robustness.
+
+Per the existing repo convention (ESP32/ADR-018, MediaTek/ADR-266-267,
+Qualcomm/ADR-268-269, RTL8720F radar/ADR-263-264), each vendor CSI/radar
+source gets its own self-delimiting envelope and its own Rust module pair
+(`wifi-densepose-hardware` for framing+codec+simulator,
+`wifi-densepose-sensing-server` for the bounded JSON-safe snapshot), never a
+shared "generic vendor CSI" struct that would either lose vendor-specific
+fields or invite magic-space collisions. `SourceKind::Realtek` (value 2) is
+already assigned to the RTL8720F FMCW radar path (ADR-263/264) and must not
+be reused for CSI.
+
+## Decision
+
+Define `RAC1` ("Realtek Ameba CSI", version 1) as a little-endian,
+self-delimiting envelope, magic `0x3143_4152` (distinct from `MTC1`
+`0x3143544d`, `QCS1` 0x31535143, `RTR1` 0x31525452, and all ADR-018
+`0xC511000x` siblings):
+
+Fixed 49-byte header (explicit field-by-field serialization, no `#[repr(C)]`
+padding, matching the MediaTek/Qualcomm modules' style):
+
+| Field | Type | Notes |
+|---|---|---|
+| magic | u32 LE | `0x3143_4152` |
+| version | u8 | 1 |
+| header_len | u16 LE | 49 |
+| frame_len | u32 LE | header + payload + 4-byte CRC |
+| node_id | u8 | disambiguates multi-board illuminator/receiver deployments; 0 = unset |
+| csi_mode | u8 | 0=passive, 1=active, 2=board-to-board (`CsiMode`) |
+| sequence | u32 LE | from firmware `csi_sequence` |
+| timestamp_us | u32 LE | from firmware `hw_assigned_timestamp` (hardware-clock microseconds, wraps ~71 min — consumers must not assume monotonic across a capture longer than that) |
+| peer_mac | [u8; 6] | firmware `mac_addr` |
+| trig_mac | [u8; 6] | firmware `trig_addr` |
+| channel | u8 | operating channel |
+| bandwidth | u8 | 0=20MHz, 1=40MHz |
+| rx_rate | u8 | firmware `rx_rate` |
+| protocol_mode | u8 | 0=OFDM,1=HT,2=VHT,3=HE (`ProtocolMode`) |
+| num_sub_carrier | u16 LE | tone count in payload |
+| num_bit_per_tone | u8 | 16 (8-bit I + 8-bit Q) or 32 (16-bit I + 16-bit Q) |
+| decimation | u8 | tone group (1/2/4/8 — every Nth tone) |
+| rssi_dbm | i8 | single RF chain (1x1 hardware) |
+| rxsc | u8 | sub-20 MHz channel used |
+| csi_valid | u8 | 0/1 from firmware |
+| flags | u8 | bit 0 = SYNTHETIC (simulator provenance, never clearable downstream) |
+| payload_len | u32 LE | bytes, == `num_sub_carrier * (num_bit_per_tone / 8)` |
+
+Payload: `num_sub_carrier` consecutive (I, Q) tone pairs, each
+`num_bit_per_tone / 16` bytes per component (1 byte/component when
+`num_bit_per_tone == 16`, 2 bytes/component little-endian signed when `== 32`)
+— i.e. exactly the byte layout the firmware already produces in
+`csi_data[]`, just framed. CRC-32/IEEE over header+payload, final 4
+little-endian bytes. One envelope per UDP datagram.
+
+Parsers reject: unknown version, wrong `header_len`, `frame_len` exceeding
+the IPv4 UDP payload cap (65,507 bytes), `num_bit_per_tone` outside
+`{16, 32}`, `payload_len` inconsistent with `num_sub_carrier *
+(num_bit_per_tone/8)`, trailing bytes, and bad CRC — mirroring the
+MediaTek/Qualcomm parser contract exactly.
+
+Host side: add `realtek_csi.rs` to both
+`wifi-densepose-hardware` (frame + codec + simulator, mirroring
+`mediatek_csi.rs`/`qualcomm_csi.rs`) and `wifi-densepose-sensing-server`
+(bounded `RealtekCsiSnapshot`, mirroring `QualcommCsiSnapshot`), wired into
+the same UDP listener loop and `/api/v1/csi/realtek/latest` route as the
+existing vendor sources. The initial Mac compatibility port keeps Realtek CSI
+as a separate bounded diagnostic stream. Fresh ESP32 frames remain the primary
+sensing source. This change does not add `SourceKind::RealtekCsi` to a signed
+ingest contract; that requires a separate reviewed identity-bound hardware
+proof. RAC1 CRC checks corruption, not origin.
+
+Firmware side (`example/wifi/wifi_csi` derivative, built against the
+official Ameba RTOS SDK, tracked outside this repository per the existing
+`CLAUDE.local.md` convention — the vendor SDK itself is never vendored into
+this repo): join the board to the deployment's WiFi AP in STA mode
+(passive CSI against the real AP as peer, since only one physical board is
+available in this bring-up), read the AP's BSSID at runtime after
+association (never hardcode a MAC into firmware source), pack each
+`RTW_EVENT_CSI_DONE` report into one `RAC1` datagram, and `sendto()` it over
+UDP to the host sensing-server's existing CSI port.
+
+## Consequences
+
+### Positive
+
+- CSI is real, MEASURED hardware output from day one — no simulator-first
+  bridge phase is needed the way MediaTek/Qualcomm required, because the
+  vendor SDK genuinely exposes the capability and we have the board in hand.
+- One board is sufficient for a first useful signal (passive CSI against the
+  home AP); active and board-to-board modes are additive later without a
+  wire-format break (`csi_mode` already reserves the values).
+- Reuses the bounded UDP parser and status-route pattern without changing
+  existing ESP32 sensing. Unsigned RAC1 diagnostics are not authorized as
+  calibrated presence, person count, pose, or vital evidence.
+
+### Negative
+
+- 1x1 hardware means no spatial (multi-antenna) diversity from a single
+  board; multi-board deployment is required for the differential/localization
+  use cases described in the original RTL8721Dx capability analysis.
+- The 71-minute microsecond timestamp wraparound (inherited from the
+  firmware's `u32` field) means long unattended captures need host-side
+  sequence-based reordering, not raw timestamp arithmetic, across a wrap.
+
+### Neutral
+
+- The RAC1 envelope intentionally does not carry the SDK's raw
+  `csi_signature` (0xABCD) marker — our own `magic`/CRC supersede it as the
+  framing integrity check.
+
+## Hardware gates
+
+- [x] Confirm SDK source exposes `RTW_EVENT_CSI_DONE` / `rtw_event_csi_report_info` (done — `component/wifi/api/wifi_api_event.h`).
+- [x] Build and flash a baseline image on real PKM8721DAF-C13-F10 hardware, confirm boot over serial (done — `feat/rtl8721dx-csi-bringup`).
+- [x] Flash the CSI-streaming firmware and confirm `RAC1` datagrams parse on the host from the real board (done, 2026-09-15 — see below).
+- [x] Record MEASURED throughput/latency/jitter from the real running firmware (done, 2026-09-15 — see below).
+- [ ] A human walk-test across the link (amplitude perturbation vs. static baseline) is deferred — requires the operator physically present; not claimed until performed.
+
+### MEASURED: real RAC1 capture and sustained throughput (2026-09-15)
+
+Passive CSI (`RTW_CSI_MODE_NORMAL`, `RTW_CSI_TRIG_BEACON | RTW_CSI_TRIG_DATA | RTW_CSI_TRIG_QOS_DATA`)
+against the deployment AP. A single `RAC1` datagram was first
+cross-checked field-by-field against the firmware's own serial log of the
+same report — every byte matched: magic `0x31434152`, RSSI byte exact match,
+channel/bandwidth/protocol/subcarrier-count exact match, 157-byte total frame
+(49-byte header + 104-byte payload + 4-byte CRC, exactly as specified above).
+
+`RTW_CSI_MODE_RX_RESP` (estimate CSI from ACKs to the STA's own transmissions)
+never fired `RTW_EVENT_CSI_DONE` across two full test runs with confirmed
+real traffic (not a hang) — this mode does not work for this hardware/AP
+combination and `RTW_CSI_MODE_NORMAL` with beacon+data triggers is the
+working configuration.
+
+**An earlier note here claimed `NORMAL` mode fires only once per CSI enable
+— that was wrong**, caused by a debug log line gated to print only every
+50th frame (`frame_count % 50 == 1`), which was misread as "only one report
+total." A follow-up capture with a UDP listener running concurrently with a
+board reset measured **277 real RAC1 datagrams in 40 seconds (43,489 bytes)**,
+with `csi_sequence` climbing continuously and monotonically in the firmware's
+own serial log across six separate 50-frame log checkpoints in one 45s
+session — CSI reporting is continuous, roughly 7-12 fps, not sparse.
+
+### MEASURED: throughput optimization pass (2026-09-15)
+
+Formalized as a repeatable tool: `scripts/benchmark-rtl8721dx-csi.py` (listens
+on the sensing-server's CSI UDP port, reports fps/throughput/RSSI/inter-frame
+interval/sequence-gap stats from real received `RAC1` datagrams).
+
+**Baseline** (`trig_period=200` [64ms], `trig_frame_ctrl=0`,
+`CSI_REPORT_BUF_NUM=1`), 30s capture:
+
+| Metric | Value |
+|---|---|
+| RAC1 fps | 14.67 |
+| Throughput | 2,302.7 bytes/s |
+| Mean inter-frame interval | 68.3 ms |
+| RSSI | mean -34.4 dBm |
+
+`trig_period` (units of 320µs) was hypothesized as the rate-limiting
+throttle — the observed 68.3ms mean interval tracks the 64ms configured
+period almost exactly. Confirmed by tuning:
+
+1. `trig_period`: 200 → 15 (the SDK doc's stated minimum recommended value,
+   ~4.8ms)
+2. `trig_frame_ctrl`: 0 → `RTW_CSI_TRIG_ACK` (second trigger source: every
+   link-layer ACK the AP sends for the heartbeat's own outgoing traffic, on
+   top of the existing beacon trigger)
+3. `CSI_REPORT_BUF_NUM`: 1 → 4 (a "lack of csi buf!" drop was observed even
+   at the slower baseline rate; more headroom needed at a higher rate)
+
+**Tuned**, 30s capture:
+
+| Metric | Value | vs. baseline |
+|---|---|---|
+| RAC1 fps | 66.40 | **4.5x** |
+| Throughput | 10,424.8 bytes/s | **4.5x** |
+| Mean inter-frame interval | 14.9 ms | 4.6x lower |
+| Sequence gaps | 78 / ~2036 (~3.8%) | new (0 observed at the slower baseline rate) |
+| RSSI | mean -31.1 dBm | (different session/position, not a controlled variable here) |
+
+The `trig_period` hypothesis is confirmed as the primary lever. The ~3.8%
+frame-loss rate at 66 fps is a reasonable place to stop for now — it is
+UDP-over-WiFi loss, not a firmware defect, and is small enough not to block
+downstream sensing use; revisit only if a use case needs stronger delivery
+guarantees (sequence-gap-triggered re-request, TCP fallback, etc.).
+
+## Links
+
+- [ADR-266](ADR-266-mediatek-filogic-csi-platform.md) / [ADR-267](ADR-267-mediatek-mimo-csi-wire-protocol.md) — sibling vendor CSI ADR pair (simulator-first precedent)
+- [ADR-268](ADR-268-qualcomm-atheros-csi-platform.md) / [ADR-269](ADR-269-qualcomm-csi-wire-protocol.md) — sibling vendor CSI ADR pair
+- [ADR-263](ADR-263-rtl8720f-2-4ghz-fmcw-radar-platform.md) / [ADR-264](ADR-264-rtl8720f-radar-wire-protocol.md) — existing Realtek (RTL8720F radar) path; `SourceKind::Realtek` owner
+- `CLAUDE.local.md` — RTL8721Dx toolchain setup, board/COM port, first bring-up log
@@ -0,0 +1,193 @@
+# ADR-345: Per-link CSI attribution and node-to-node ranging
+
+- **Status**: Proposed — measurement layer implemented and validated on hardware; localization not built
+- **Date**: 2026-08-28
+- **Deciders**: Joe
+- **Tags**: csi, wire-format, esp32-c6, localization, adr-018, adr-060, adr-110
+
+## Context
+
+Every attempt at device-free position estimation in this repository has failed
+against the same wall, and the wall has now been measured twice from different
+directions.
+
+**Phase is unusable.** The bistatic tier needed a signed per-link radial
+velocity, which requires the common-mode component of CSI phase. Measured
+2026-08-28 across all three ESP32-C6 nodes over ~40,000 frames, the
+frame-to-frame change in common-mode phase is statistically indistinguishable
+from uniform random — resultant length `R` = 0.011–0.032 against a 0.000
+reference, standard deviation 1.78–1.81 against `pi/sqrt(3)` = 1.814, and no
+lag-1 autocorrelation. A second, unwrap-free estimator agreed. The mechanism is
+packet-detection timing quantization: common-mode phase is `-2*pi*f_c*tau`, and
+one ADC sample of jitter at 20 MHz is `2*pi * 2.412e9 * 50e-9` ~= 758 rad, about
+120 full wraps, re-randomized every packet. Not calibratable. The bistatic tier
+is default-off as a result (`bistatic_tier_enabled`).
+
+**Amplitude works but had no parallax.** The three AP -> node links leave a
+single distant transmitter within a 36.5 degree fan and converge on the node
+cluster. Bearings computed from `room_config.json`: 198.5, 221.2, 235.0 degrees.
+Scalar per-node energy weighting was closed with a clean negative result on
+2026-08-27 — magnitude responds to proximity, direction does not.
+
+**The receivers were hearing far more than we recorded.** A node in promiscuous
+MGMT+DATA mode with no `filter_mac` produces CSI for every transmitter on the
+channel. Measured on node 2: the AP accounted for only **34%** of frames; the
+two peer nodes supplied 39% and 27%. Those peer frames are valid measurements
+of *node-to-node* channels — but ADR-018's wire format carries no transmitter
+address, so the sink could not attribute them. They interleaved into one
+`frame_history` with mixed geometry, and the only available remedy
+(`filter_mac`, ADR-060) fixes the mixing by discarding ~75% of the data.
+
+The node-to-node links between the same three boards cross the room from three
+sides at **108.7 degrees** of angular spread (bearings 0.0, 73.2, 108.7) versus
+36.5 for the AP links — roughly 3x the parallax, with both endpoints known,
+fixed, and under our control rather than wherever the router happens to live.
+Link count also grows as `N*(N-1)/2`: 3 nodes give 3 links, 6 give 15, 13 give
+78.
+
+## Decision
+
+Carry the transmitter MAC on the CSI wire and model CSI per **link**
+(receiver, transmitter) rather than per **node**, as a layer alongside the
+existing per-node model.
+
+### 1. Wire format v2
+
+`CSI_MAGIC_V2 = 0xC5110008`, header 26 bytes: the v1 header unchanged through
+byte 19, then the transmitter address (`info->mac`, 802.11 addr2) at bytes
+20..25, with I/Q from byte 26.
+
+`0xC5110002`..`0xC5110007` were already claimed by the vitals, feature and other
+edge packets, so v2 takes the next free value rather than an adjacent one — see
+`issue_928_magic_collision_tests` for why that matters. The parser accepts both
+magics, so a mixed fleet keeps working and v1 nodes simply report no
+transmitter.
+
+### 2. Per-link state (`links.rs`)
+
+`LinkTable` keyed by `LinkId { rx_node, tx_mac }`, each link holding its own
+amplitude history, RSSI EMA, learned resting baseline and motion metric.
+
+The metric is the mean over subcarriers of the temporal standard deviation of
+**AGC-normalized** amplitude. Removing each frame's own mean across subcarriers
+is essential rather than cosmetic: the ESP32 applies automatic gain control per
+packet, so absolute amplitude jumps between packets for reasons unrelated to the
+channel, and any statistic built on the raw level measures the radio's gain
+control instead of the room.
+
+Amplitude only, deliberately — nothing here can depend on phase coherence.
+
+### 3. Beacon rate
+
+`BEACON_PERIOD_MS` 100 -> 20. At 10 Hz a peer samples a node-to-node link with a
+5 Hz Nyquist while motion Doppler lives at 1–20 Hz; it aliases before it starts.
+20 ms matches both the receiver's own `CSI_MIN_PROCESS_INTERVAL_US` ceiling and
+the gateway self-ping already used for the AP link.
+
+### 4. `GET /api/v1/links` and a live UI panel
+
+The link table was initially reachable only through a 30-second log line, which
+is the wrong medium for a quantity whose value is watching it respond while you
+walk across the room. `GET /api/v1/links` returns one row per link — `motion`,
+`raw_motion`, `rssi_dbm`, `frames`, `kind` — and `LinkMeshPanel` renders them in
+the Sensing tab at 1 Hz. `raw_motion` is shown beside `motion` deliberately: a
+link whose baseline has not settled reports a healthy raw value and a near-zero
+motion, and with only the one number that is indistinguishable from a dead link.
+
+Node identity is **inferred, not measured**. Nothing in the system records a
+node's own MAC — a node reports the addresses it hears, never its own. But a
+radio does not receive its own transmissions, so given the set of receivers
+currently reporting, a transmitter heard by all of them except exactly one is
+that one receiver's own board; a transmitter heard by every receiver is external
+infrastructure. `links::infer_transmitting_node` declines (returns `None`) with
+fewer than three receivers, where "heard by all but one" and "heard by exactly
+one" are the same observation, and whenever more than one receiver is missing,
+which a peer out of range produces indistinguishably. The field is named
+`tx_node_inferred` and the UI draws the peer id with a trailing `?`.
+
+Checked against the known MAC map on 2026-08-28 the inference labelled all four
+transmitters correctly — nodes 0, 1 and 2 by address, and the AP as external —
+with no access to that map. A wrong answer here mislabels a display row; it
+never reaches a metric.
+
+## Consequences
+
+### Validated on hardware, 2026-08-28
+
+All three nodes on wire v2 at 20 ms produced the full mesh: **9 links** (3 AP +
+6 directional node-to-node).
+
+Reciprocity — each physical channel measured independently from both ends:
+
+| channel | direction A | direction B | ratio |
+|---|---|---|---|
+| 0 <-> 1 | 2.229 | 1.930 | 1.15 |
+| 0 <-> 2 | 1.353 | 1.000 | 1.35 |
+| 1 <-> 2 | 1.398 | 1.486 | 1.06 |
+
+Nothing in the implementation enforces this. Three independent radio pairs
+agreeing within 6–35% is the strongest available evidence that the per-link
+separation is real rather than an artifact of frame bucketing.
+
+Link quality is also far more uniform than the AP links: node-to-node raw motion
+spans 1.0–2.2 across all six, versus 3.8–17.8 for the three AP links (which
+track RSSI: -67, -72, -80). Uniform link quality is desirable for tomographic
+localization — no single link dominates the solution.
+
+### Known limitations
+
+- **Peer links are ~10x weaker.** A 16-byte ESP-NOW beacon offers far less
+  energy to estimate a channel response from than a full data frame. Whether
+  1.0–2.2 perturbation is sufficient to localize with is **unknown and untested**.
+- **Three links is below threshold.** Tomographic localization needs many
+  crossing links; 3 will not localize regardless of quality. This ADR delivers
+  the measurement layer, not localization.
+- **Localization is not implemented.** No position tier consumes `LinkTable`.
+  The live position estimate remains `doppler_centroid`.
+- **Per-node path regression.** Removing `filter_mac` to admit peer frames
+  returned the *per-node* `frame_history` to a mixed-transmitter stream, since
+  it still consumes every frame regardless of source. Node 2's classification
+  signal is noisier as a result. The fix is to select a link to feed the
+  per-node path — software filtering that keeps the other links — and it is not
+  yet done.
+
+### Scaling limits to settle before more nodes
+
+- **Airtime.** Every node broadcasts, so N nodes put N/period frames per second
+  on the channel being sensed. 3 nodes at 20 ms is 150 pps; 13 would be 650 pps.
+  `BEACON_PERIOD_MS` should become an NVS setting scaled to fleet size.
+- **`MAX_LINKS` is 64.** 13 nodes give 78 receiver-transmitter pairs plus the AP
+  plus neighbours, which overflows. Raise deliberately, with the memory implied.
+- **Placement.** Links must *cross* the target area. Nodes spread through a
+  house give roughly one link per room, each attenuated by walls and perturbed
+  by anyone anywhere along it — whole-house coarse presence, not position.
+  Perimeter placement around a single room is the geometry that works.
+
+## Related bugs found and fixed while implementing
+
+- **ADR-060 MAC filtering cost ~75% of capture rate.** The 50 Hz rate gate ran
+  *before* the MAC filter and stamped `s_last_process_us` before the check, so a
+  frame from any other transmitter consumed the slot and was then discarded.
+  Enabling `filter_mac` dropped yield from ~42 pps to 6–13. Filtering first
+  restores it (measured 31–37 pps). A 6-byte `memcmp` is negligible ISR work next
+  to the CSI processing the gate guards.
+- **The entire edge pipeline was dead on ESP32-C6.** `EDGE_MAX_SUBCARRIERS` was
+  128, an S3-era assumption; a C6 on an HE-capable AP delivers HE20 frames with
+  256 bins, and `process_frame` rejected every one. ADR-110 onboarded the C6 to
+  the capture path but not this one. Vitals, presence, fall detection and
+  per-slot counting had never run on these boards. Now target-conditional on
+  `CONFIG_SOC_WIFI_HE_SUPPORT`, with the four subcarrier-sized arrays hoisted to
+  static so peak stack is *lower* than it was at 128.
+- **A target-conditional constant that failed silently.** `edge_processing.h`
+  had no `#include` at all, so `CONFIG_SOC_WIFI_HE_SUPPORT` was undefined and
+  `#if` evaluated it as 0 — selecting the wrong size with no warning. An
+  undefined identifier in `#if` is 0 in C. This is the same failure mode as the
+  bug it was fixing, one layer up.
+
+## References
+
+- `v2/crates/wifi-densepose-sensing-server/src/links.rs` — per-link state, 8 tests
+- `v2/crates/wifi-densepose-sensing-server/src/phase_diag.rs` — the phase measurement
+- `firmware/esp32-csi-node/main/csi_collector.c` — wire v2 serialization, filter ordering
+- `firmware/esp32-csi-node/main/edge_processing.h` — `EDGE_MAX_SUBCARRIERS`
+- ADR-018 (wire format), ADR-060 (MAC filtering), ADR-110 (C6 onboarding)
@@ -0,0 +1,134 @@
+# ADR 355: Local empty room bootstrap prior
+
+Status: Accepted
+
+Date: 2026-09-04
+
+## Context
+
+Most installations are occupied when RuView first starts. An uncalibrated
+signal heuristic can interpret HVAC, clock error, neighboring motion, or a
+short covariance window as a person. It can also surface plausible numeric
+vitals before a room model establishes occupant attribution.
+
+One empty home is not representative training data for all homes and contains
+no positive human examples. It is useful only as a recent negative prior for
+the same installation. It cannot define a universal human signal model.
+
+The field model was memory only. The server also used a relative `data/`
+directory, which is unreliable for embedded application hosts.
+
+## Decision
+
+RuView may persist a completed empty room field model as a local bootstrap
+prior only after two server controlled stages:
+
+1. Normal calibration reaches both 1,000 accepted frames and 600 seconds.
+   The frame target represents twenty complete fifty frame runtime windows.
+   A caller may select one currently live ESP32 source. The server checks its
+   freshness before replacing an active bootstrap prior, binds collection to
+   that source, and rejects frames from other radios. When no source is
+   selected, the first accepted ESP32 source preserves legacy behavior.
+2. Promotion observes 12 new samples spaced by at least one second. Each
+   sample has a four second bounded acquisition timeout. At least 10 must
+   resolve empty, all ticks must be fresh, and none may publish numeric vital
+   signs.
+
+The stored image contains aggregate means, environmental modes, mode energies,
+noise statistics, sorted scalar residual references, configuration, one source
+node ID, and a server generated model ID. It excludes raw CSI, waveforms,
+device addresses, room names, pose, identity, credentials, and positive human
+labels. Runtime matching compares a fifty frame mean with the learned residual
+distribution. Its score is empirical background conformance, not an absence
+probability.
+
+The image is bound to a SHA 256 digest of the stable installation ID, carries
+an integrity digest over the exact stored payload bytes, is capped at 1 MiB,
+and inherits the field model expiry.
+Files with an invalid schema, dimensions, values, node set, installation
+binding, digest, size, or lifetime fail closed.
+
+Restoring an image creates a field model in `bootstrap_only` mode. It may
+reduce an uncalibrated false person count, but it cannot authorize calibrated
+evidence or numeric heart and breathing rates. Explicit calibration replaces
+it with fresh statistics. Cancelling an unfinished capture restores a valid
+prior. Administrator scoped reset removes it.
+
+A restored image may receive one operator confirmed held out empty refinement.
+The server measures 12 fresh, source bound runtime residuals at one second
+spacing and requires zero stale samples and zero numeric vital samples. It
+persists only the scalar residuals. The new boundary is the larger of the
+existing threshold and 110 percent of the held out 95th percentile, capped at
+125 percent of the prior threshold. The one use marker persists in the model,
+so repeated requests cannot ratchet the threshold upward.
+
+The status endpoint reports the learned runtime window, residual threshold,
+reference count, current background conformance, and the negative only
+authority boundary. A restored model never resumes collection and never
+persists raw calibration frames.
+
+The server accepts `--data-dir` or `RUVIEW_DATA_DIR`, allowing an application
+host to provide a protected state directory.
+
+## Consequences
+
+Startup can use recent measured background structure instead of only generic
+heuristics. No accuracy lift is claimed until occupied and empty held out data
+from multiple installations is recorded.
+
+The largest failure mode is overfitting to a temporarily quiet home and
+suppressing a weak occupant. Controls are low authority, 24 hour expiry,
+installation binding, vital abstention, explicit recalibration, and reset.
+
+A human signal model still requires positive, consented, leakage separated
+occupied sequences. Empty data is never relabeled as human training.
+
+## Implementation
+
+1. `wifi-densepose-signal::ruvsense::field_model` exports and validates
+   `FieldModelSnapshotV1`.
+2. `wifi-densepose-sensing-server::bootstrap_baseline` owns schema, integrity,
+   storage, lifetime, and the held out gate.
+3. `POST /api/v1/calibration/bootstrap/promote` measures the validation window
+   and stores the image only on pass.
+4. `GET /api/v1/calibration/status` reports bootstrap authority and explicitly
+   denies calibrated evidence and numeric vital authority.
+5. Numeric vitals fail closed unless an explicit fresh calibration resolves
+   exactly one occupant at sufficient signal quality and confidence.
+6. The legacy `edge_vitals` WebSocket message applies the same publication
+   gate as `sensing_update`. When the bootstrap background matches, it emits
+   absent state, zero people, null numeric rates, and an explicit abstention
+   reason instead of forwarding raw edge candidates.
+7. `POST /api/v1/calibration/start?source_node_id=N` selects a live source for
+   deterministic single link capture. A missing or stale selection fails
+   without disabling the active bootstrap prior.
+8. `POST /api/v1/calibration/bootstrap/refine?confirmed_empty=true&source_node_id=N`
+   performs the bounded one time held out refinement. It requires administrator
+   authority when transport authentication is enabled.
+
+## Measured installation evidence
+
+One physical empty home run on source Node 5 collected 1,762 accepted frames
+over 655 seconds and produced 35 privacy reduced reference windows. Promotion
+observed 12 of 12 fresh empty samples, zero stale samples, and zero numeric
+vital samples. After process restart, 12 of 12 fresh samples matched the empty
+background and contained no numeric vital signs. Background conformance scores
+ranged from 50.0 to 64.3 percent with a median of 54.3 percent.
+
+This is measured negative evidence for one installation. No occupied positive
+holdout was recorded, so it does not prove person recall, person counting, or
+cross home accuracy improvement.
+
+## Acceptance test
+
+With a physically empty room, complete calibration on stable nodes, promote
+the single source model, and restart the server with the same installation ID
+and data directory. Status must report `binding_mode=bootstrap_only`, zero
+collection frames, and false authority for calibrated evidence and numeric
+vitals. Twelve fresh empty samples must contain no numeric vital signs.
+Starting a new room calibration must replace the prior and begin at frame zero.
+When several radios are live, selecting Node 5 must leave Nodes 3 and 7 out of
+the source set for the entire capture.
+After restart, a confirmed empty holdout may refine the restored boundary once.
+The stored snapshot must reject a second refinement and must continue to deny
+calibrated evidence and numeric vital authority.
@@ -0,0 +1,151 @@
+# ADR 356: Rate truthful CSI and reliability gated room adaptation
+
+Status: Accepted
+
+Date: 2026-09-05
+
+## Context
+
+RuView mixed three different notions of time. ESP32 firmware requested a packet
+rate, the server observed a delivered rate, and several server paths still used
+fixed 2 Hz, 10 Hz, or 20 Hz assumptions. One feature named
+`dominant_freq_hz` was not a temporal frequency at all. It was the index of the
+strongest subcarrier multiplied by 0.05. A second defect compared a newly
+inserted frame with itself, forcing that motion delta to zero.
+
+These errors can move a spectral peak into the breathing or heartbeat band and
+produce plausible but false values. They also make models sensitive to WiFi
+traffic and processor scheduling rather than physical motion.
+
+ESP-IDF documents that `wifi_csi_info_t.first_word_invalid` marks the first four
+CSI bytes invalid because of a hardware limitation. It also documents that the
+CSI receive callback runs in the WiFi task and should hand work to a lower
+priority task rather than perform lengthy processing. RuView serialized the
+invalid bytes unchanged and fed the original buffer to edge processing.
+
+Recent work suggests four useful directions with different maturity:
+
+1. OpenCSI represents each link as a dimensionless residual against its own
+   quiet period temporal standard deviation and exposes baseline maturity. Its
+   reported transfer results are limited to binary presence.
+2. MORIC derives motion centered delay and Doppler views to reduce dependence
+   on static environment specific CSI structure.
+3. Parameter efficient CSI crowd counting combines self supervised pretraining,
+   small room adapters, and a stateful counting machine.
+4. WiFi JEPA masks complete radio links and predicts their latent embeddings,
+   using real and ray traced CSI for pose representation learning.
+
+The papers report promising external results. None is measured RuView evidence,
+and none authorizes deployment without leakage free occupied and empty held out
+evaluation.
+
+## Decision
+
+### Firmware ingestion
+
+1. When ESP-IDF marks the first CSI word invalid, zero the first four serialized
+   CSI bytes while retaining the fixed packet shape.
+2. Set ADR-018 byte 19 bit 5 to record that sanitation occurred.
+3. Feed edge DSP from the sanitized serialized payload, never the original
+   invalid driver buffer.
+4. Keep callback work bounded to sanitation, serialization, and the existing
+   queue handoff. Do not add transforms to the WiFi task.
+
+### Server time model
+
+1. Estimate delivered CSI rate from accepted monotonic frame timestamps after
+   five samples. Use 20 Hz only during startup.
+2. Cap the physical input rate at the firmware contract of 50 Hz so a burst or
+   timestamp artifact cannot retune downstream filters above their supported
+   range.
+3. Reconfigure the vital detector only after a 20 percent rate change. Clear
+   temporal and smoothing state whenever its clock changes. Samples calculated
+   with different clocks must never be blended.
+4. Compute temporal dominant frequency from the recent mean amplitude series
+   with demeaning, a Hann window, and bounded direct Fourier bins from 0.1 Hz to
+   the smaller of 4 Hz or 45 percent of sample rate.
+5. Return zero for short, flat, nonfinite, or spectrally ambiguous windows.
+6. Compare the current frame with the prior frame, not itself, for motion delta.
+7. Export zero sample rate until the estimate is mature. Never present a startup
+   fallback as a measured node property.
+
+### Model compatibility and room reliability
+
+1. Preserve the historical fifth input feature for version 1 adaptive models at
+   the model boundary. Version 2 and later models consume the true temporal
+   frequency. This prevents an existing model from silently receiving a
+   different input distribution after a server update.
+2. A background model is unreliable until it contains at least ten finite,
+   nonnegative residual references. An unreliable model cannot suppress a
+   runtime change and exposes no conformance score.
+3. Expose background maturity, reliability, and a robust residual Z score based
+   on the median and median absolute deviation.
+4. Keep the persisted empty home prior negative only. It cannot authorize
+   calibrated presence, person count, pose, or numeric vitals.
+
+### Model roadmap
+
+The following work remains proposal only:
+
+1. Evaluate an OpenCSI style per link quiet residual normalization for binary
+   presence without replacing absolute magnitude features used for motion.
+2. Evaluate delay and Doppler views after phase sanitation for activity.
+3. Pretrain a frozen multilink encoder and adapt small room specific modules for
+   counting.
+4. Evaluate link masked self supervision for pose only when at least three
+   spatially distinct links and synchronized positive pose labels exist.
+
+Every candidate uses immutable manifests and splits by room, subject,
+recording, and time. It is compared with the frozen baseline under identical
+seeds. Counting includes confusion matrices and mean absolute error. Pose
+includes PCK at 20 centimetres, MPJPE, and the mean pose baseline. A shuffled
+label control must fail.
+
+Promotion requires at least 10 percent held out lift, less than 10 milliseconds
+added p95 inference latency, no more than 20 percent peak memory overhead, zero
+leakage or secret findings, frozen anchor retention, and no regression in empty
+rejection or occupied recall. Promotion remains an explicit maintainer action.
+
+## Consequences
+
+The firmware no longer preserves a known invalid prefix as sensor evidence. The
+server uses an observed physical clock for spectral features and vital filters.
+Existing version 1 adaptive models remain compatible. Sparse background samples
+fail open to observation and fail closed for suppression.
+
+The direct Fourier estimator is intentionally small and bounded to 128 temporal
+samples. It is portable and deterministic, but it is not a replacement for a
+phase sanitized delay and Doppler pipeline.
+
+The largest remaining uncertainty is human recall. Empty home evidence can
+measure false presence but cannot show whether weak occupied signals are being
+suppressed. The fix path is a consented, leakage separated occupied holdout with
+multiple spatial links and synchronized reference labels.
+
+## Research basis
+
+1. Espressif ESP-IDF WiFi CSI programming guide:
+   https://docs.espressif.com/projects/esp-idf/en/v5.5.4/esp32/api-guides/wifi.html
+2. Espressif ESP CSI reference implementation:
+   https://github.com/espressif/esp-csi
+3. OpenCSI:
+   https://arxiv.org/abs/2607.26665
+4. MORIC:
+   https://arxiv.org/abs/2506.12997
+5. Parameter efficient CSI crowd counting:
+   https://arxiv.org/abs/2601.02203
+6. WiFi JEPA:
+   https://arxiv.org/abs/2607.11064
+
+## Acceptance test
+
+Run the firmware serializer host tests and the focused hardware, signal, and
+sensing server Rust suites. The deterministic serializer test must prove the
+first four bytes are zero only when ESP-IDF marks them invalid and bit 5 must
+round trip through the Rust parser. The temporal estimator must recover a
+1.2 Hz synthetic signal within 0.21 Hz, abstain on short and flat inputs, and
+remain below 10 milliseconds p95 on the target Mac. Existing version 1 model
+input must retain the legacy proxy. A background model with nine references
+must never report a match or suppress a runtime change. Physical firmware is
+not qualified until an S3 and C6 boot and stream the sanitized flag without
+watchdog, memory, or transport regressions during a five minute burn in.
@@ -0,0 +1,143 @@
+# ADR 357: Raw CSI calibration sample integrity
+
+Status: Accepted
+
+Date: 2026-09-06
+
+## Context
+
+The empty room field model requires 1,000 accepted observations over at least
+600 seconds. The sensing server previously invoked calibration from both the
+raw CSI path and the one second edge vital path. Edge vital packets did not add
+a CSI observation, so that path repeatedly fed the existing history tail. A
+counter could therefore satisfy the frame gate without representing 1,000
+independent CSI packets.
+
+Node liveness also combined edge vital and CSI traffic. A source emitting only
+edge vital summaries could appear live enough to start calibration even though
+it had no fresh raw CSI. Finally, cloning the complete per node history before
+each feed copied as much as 204,800 bytes for a 100 frame, 256 subcarrier
+window even though calibration consumes only the current observation.
+
+The earlier single installation result recorded in ADR 355 predates this
+admission boundary. Its frame count is not accepted as evidence of independent
+CSI coverage. It remains useful only as diagnosis of the failure mode and must
+not be promoted as a production bootstrap prior.
+
+## Decision
+
+1. Only a packet on the frozen, model specific CSI grid may advance field
+   calibration. Edge vital packets update their own health and presentation
+   state but never feed the field model. The independent live inference grid
+   remains unchanged.
+2. Each calibration session stores the last admitted wrapping sequence for
+   every contributing node. Duplicate sequences are ignored. Normal forward
+   progress and the `u32::MAX` to zero wrap are accepted.
+3. A packet one through sixteen sequence values behind the current high water mark
+   is bounded UDP reordering. It is recorded and dropped without feeding the
+   model or moving the high water mark. A backward depth above sixteen, or an
+   ambiguous half range sequence, latches that node as faulted for the remainder
+   of the session. Status exposes the policy, reorder window, per node reorder
+   count, maximum observed depth, and `sequence_fault_node_ids`. Finalization
+   returns `calibration_sequence_discontinuity` after a fault. The operator must
+   cancel and restart the empty room capture.
+4. A requested source may start calibration only after a header only, bounded
+   observation window identifies one stable grid. The selected grid needs at
+   least ten seconds of evidence, a measured rate of at least 2 Hz, a latest
+   sample newer than five seconds, and no observed gap of five seconds or more.
+   Calibration status reports the immutable grid, selection evidence, current
+   grid age, and `last_sequence_by_node` without exposing CSI values.
+5. Start, cancel, reset, and process initialization clear sequence admission
+   state. A failed feed does not advance the sequence cursor, so the same
+   packet may be retried after a transient model input failure.
+6. The field bridge receives the current amplitude slice rather than a cloned
+   history. A separate bounded runtime history retains only that same frozen
+   grid, so the model is never trained on one symbol layout and evaluated on a
+   different layout. Canonical grid normalization remains unchanged.
+7. The exact source grid is stored inside the digest protected bootstrap v2
+   payload. A restored model rebuilds only its matching runtime history. An
+   unbound legacy image cannot become an active startup prior.
+8. Successful finalization clears the selected grid runtime history. Bootstrap
+   promotion waits up to 35 seconds for a complete fresh runtime window before
+   scoring twelve additional samples. This covers a 50 frame window at the 2 Hz
+   admission floor plus ten seconds of bounded jitter. Calibration observations
+   therefore cannot enter the held out decision window.
+9. Stop and promotion require the frozen grid to remain fresh and reject any
+   latched sequence fault immediately before persistence. Bootstrap v2 accepts
+   exactly one source node because the current runtime supports one grid bound
+   field model.
+10. The legacy `--calibrate` startup switch fails closed before opening ports.
+    Grid evidence does not exist at process start, so operators start the server,
+    wait ten seconds, then call the explicit single source calibration API.
+
+## Consequences
+
+Calibration frame count now means unique, forward raw CSI observations within
+one uninterrupted sequence epoch. A vitals only node cannot produce a
+bootstrap model. Late packets never become calibration evidence.
+
+One physical Node 5 capture observed sequence 4,119,566 followed by 4,119,563,
+4,119,564, and 4,119,565 in one receive batch. A second independent 90 second
+capture observed bounded late packets at depths 9, 10, and 11. The window of
+sixteen covers the measured maximum with five positions of margin. At the
+firmware acceptance ceiling of 50 Hz, the window represents no more than 320
+milliseconds. Late packets are always dropped. Larger regressions remain
+failed closed.
+
+The same 90 second capture measured three interleaved HT grids on Node 5. The
+64 subcarrier stream delivered 436 frames at 4.84 Hz with a 1.56 second maximum
+gap. The 128 stream delivered 100 frames at 1.11 Hz with a 5.05 second maximum
+gap. The 192 stream delivered 49 frames at 0.54 Hz with an 11.53 second maximum
+gap. Only the 64 grid exceeded the 2 Hz admission floor and stayed inside the
+five second freshness boundary, so the final field model binds to that grid.
+
+The current wire format still has no authenticated boot epoch or stable device
+identity. A restart very early in a session or a same endpoint adversary cannot
+be distinguished cryptographically. A future ADR 018 revision must carry an
+authenticated device identifier and a random per boot identifier before the
+server claims exact restart or identity collision detection.
+
+No new raw CSI is persisted. Sequence cursors and fault markers remain bounded
+in memory to active calibration sources. The bootstrap schema advances to v2
+to protect the grid identity while its negative only authority remains
+unchanged.
+
+## Implementation
+
+1. `NodeState` records header only recent grid evidence and a separate bounded
+   field model history.
+2. `AppStateInner::maybe_feed_calibration_frame` owns source binding, sequence
+   ordering, fault latching, model feed, and cursor commit.
+3. `field_bridge::maybe_feed_calibration` accepts exactly one current amplitude
+   slice and rejects an empty observation.
+4. Calibration start, status, stop, cancel, reset, promotion, refinement, and
+   restart enforce the frozen source and grid contract.
+5. `bootstrap_baseline` persists the source grid inside the verified v2 image.
+6. Finalization clears training history, and promotion blocks until the model
+   has a complete fresh scoring window plus twelve separately spaced samples.
+7. Startup calibration without measured grid evidence exits with a typed
+   operator instruction instead of creating a model that can never receive a
+   frame.
+
+## Acceptance test
+
+Unit tests must prove stable grid selection, rate and gap rejection, first
+packet acceptance, forward progress, duplicate rejection, source and grid
+isolation, maximum counter wrap, empty input retry, measured depth eleven
+reordering without a model feed, depth sixteen acceptance, depth seventeen
+latching, half range rejection, session clear, receipt visibility, protected
+grid persistence, and typed stop refusal.
+Tests must also prove startup flag refusal, missing and stale grid refusal,
+complete holdout isolation, and sequence fault rejection during holdout.
+
+On physical hardware, begin a Node 5 empty room capture and observe a fresh
+sixty second interval. Calibration frame growth must match unique 64 subcarrier
+Node 5 sequences while the independent global inference grid remains unchanged.
+Edge vital packets and other grids must produce zero growth. The bound grid
+must remain active, sequence faults must remain empty, and numeric vital output
+must remain absent. Any bounded late packet must appear in the reorder receipts
+while leaving the model count unchanged. Complete both the 1,000 frame and 600
+second gates, then run the twelve sample server controlled bootstrap holdout.
+Restart and prove that only the persisted grid rebuilds the runtime history.
+Do not claim human detection improvement until a separate consented occupied
+holdout demonstrates retained recall.
@@ -0,0 +1,110 @@
+# ADR-361: Point the whole fleet at one transmitter, to remove selection ambiguity
+
+**Status:** Proposed — built, deployed fleet-wide, A-B-A measured. **Hypothesis CONFIRMED, adoption NOT justified.** The pairing *fraction* rises sharply; paired observations per second fall.
+**Date:** 2026-09-09
+**Follows:** ADR-358 (falsified), ADR-359 (mechanism confirmed, not adopted), ADR-360 (falsified).
+
+## The hypothesis, recorded long before it could be tested
+
+From `docs/BACKLOG.md`, "Next: the actual pairing constraint":
+
+> Two nodes can therefore fire in the same aligned window and still pick frames
+> from *different* transmitters, which can never pair under the
+> `(tx_mac, rx_seq)` key. Cheapest test and likely fix: **point the whole fleet
+> at one strong transmitter with the existing ADR-060 MAC filter.**
+
+It had never been run, and the reason was mechanical rather than scientific:
+**`filter_mac` was writable only by `provision.py` over USB.** It is a 6-byte
+blob, absent from the `cfg_key_t` scalar table the config API validates
+against, so the test would have required nine physical visits. Exposing it over
+the network (see the firmware change accompanying this ADR) reduced the whole
+experiment to two config pushes.
+
+## What was measured
+
+The associated AP was chosen on measurement, not assumption. Five transmitters
+reach all nine receivers; only one carries a usable rate:
+
+```
+transmitter            n_rx  total_fps  mean_rssi
+8c:30:66:86:a4:21        9      109.81     -66.6   <- the AP, 26x the next
+96:30:66:86:a4:21        9        4.24     -65.9
+08:36:c9:71:ff:52        9        0.18     -75.9
+64:16:66:cb:17:07        9        0.08     -81.7
+10:a5:62:24:bb:30        9        0.06     -78.2
+```
+
+A-B-A, ten 30 s windows per arm. `/api/v1/fusion` counters are cumulative since
+sink start, so they are **differenced over each window** and never divided as
+lifetime totals — the trap already recorded for `early_drop`/`csi_fps_samples`.
+The filter applied live on all nine nodes with **no restart**, so no reboot
+confounds any arm.
+
+```
+arm            n   paired_fraction        tx/s    paired/s
+A1 control    10   0.5668 +/- 0.0107      73.0     41.4
+B  filtered   10   0.7287 +/- 0.0352      33.9     24.7
+A2 control    10   0.5836 +/- 0.0120      81.5     47.6
+```
+
+**Pairing fraction +0.1535 against the pooled control (+26.7% relative),
+Welch t = 13.26, df = 10.5, p < 0.0001.** Reversible: A2 returned to control,
+0.0168 against A1.
+
+Per-node confirmation that the filter did what it claims, taken on node 3 while
+eight nodes were still unfiltered:
+
+```
+node 3 (filtered)   AP fps 13.56   non-AP fps 0.28   non-AP share  2.0%
+node 8 (control)    AP fps 12.18   non-AP fps 5.66   non-AP share 31.7%
+```
+
+The AP rate is untouched; peer traffic falls to residue.
+
+## The hypothesis is confirmed. The fix is not.
+
+Transmitter ambiguity **was** suppressing pairing, and removing it lifts the
+fraction by a quarter. That settles a question that had been open since
+2026-09-07 and had resisted three other experiments.
+
+But the backlog called this the "likely fix", and that half does not survive.
+It predicted yield would fall to ~13 fps and that "the frames that remain are
+pairable". Both are true, and neither is sufficient:
+
+- **tx/s fell 56%** (77.3 -> 33.9)
+- **paired observations per second fell 44%** (44.4 -> 24.7)
+
+A higher fraction of a much smaller pie. The quantity downstream sensing
+actually consumes is paired observations per second, and that went **down**.
+Fraction was the wrong figure of merit, and choosing it is what made this look
+like a fix rather than a diagnosis.
+
+## Decision
+
+**Do not adopt. Keep the branch unmerged.** Production stays unfiltered,
+`gate_mode=2`, `gate_seq_period=8`.
+
+`filter_mac` **is** kept in the config API. It costs nothing when unset, it is
+now the cheapest available probe for "is this node's pairing transmitter-
+limited?", and the ADR-060 filter had been effectively unreachable for the
+fleet's whole life.
+
+## What this opens
+
+A **partial** filter is the obvious next question and is NOT what was tested
+here. Restricting to a handful of widely-heard transmitters rather than exactly
+one would trade less yield for some of the gain, and there is no reason to think
+the optimum is at either extreme. The five 9-receiver transmitters above are the
+natural candidate set, though four of them carry almost no rate.
+
+That is a new experiment with a different independent variable, not a variant
+of this one. It should be sized on **paired observations per second**, which is
+the lesson this ADR paid for.
+
+## Honest scope
+
+Software-only. One house, one AP, nine nodes, ~15 minutes per arm, at 05:00
+local with the house quiet. The effect is far larger than the within-arm
+scatter and it reversed cleanly, but it has not been repeated across times of
+day, and pairing is known to move with the transmitter population (see
+"Transmitter population instability", 2026-09-02).
@@ -0,0 +1,69 @@
+# ADR-362: Reading the on-node log is on-demand, never streamed
+
+**Status:** Accepted
+**Date:** 2026-09-09
+**Follows:** the on-node log engine (persistent 128 B-record ring + coredump-to-flash)
+
+## Context
+
+The firmware now keeps a persistent log on the node's `storage` volume and can
+write a coredump to flash. Nothing reads either one. The log is a new concept
+in this tree, so there is no existing consumer to extend and the access
+pattern is genuinely open.
+
+Two shapes were considered:
+
+1. **Ingest** — the server polls every node on a schedule, drains new records,
+   and keeps its own copy that the UI reads.
+2. **On-demand** — the server fetches a node's log only when a human asks for
+   it, and keeps nothing.
+
+## Decision
+
+**On-demand only. No streaming, no periodic polling, no server-side copy, no
+alerting.**
+
+The log is pulled after a board hangs or crashes, or while troubleshooting a
+specific node. That is the whole access pattern.
+
+## Why
+
+- **The persistence already lives on the node.** The ring holds ~208 days at
+  128 B per 300 s, and surviving a power cycle is the entire reason the module
+  exists — a power cycle is how a wedged node gets recovered. A second copy on
+  the server duplicates a durability property that is already satisfied.
+- **Airtime is this fleet's binding constraint, and it is the thing being
+  diagnosed.** Two nodes uplinking at 1 Mbps were measured consuming 91% of
+  fleet airtime. A periodic log drain across nine nodes would spend exactly the
+  resource whose exhaustion is the most common thing you would open the log to
+  investigate. An instrument must not perturb what it measures.
+- **Coredumps are 64 KB.** They are only ever worth moving when something has
+  actually crashed.
+- **The use is diagnostic, not observational.** Nobody watches nine logs. You
+  open one node's history when that node misbehaves.
+
+## What this implies gets built
+
+- A server route that proxies to the node on request — `GET
+  /api/v1/nodes/{id}/log`, and the same for `/coredump` — authenticating with
+  the OTA PSK the firmware endpoints already sit behind.
+- A page under the existing Tools menu to view one node's records.
+- **No** scheduler, **no** new storage, **no** retention policy on the server.
+
+## Open question, deliberately not settled here
+
+Whether the server decodes the 128 B records into JSON, or proxies raw bytes
+and lets the decoder at the edge (browser, or `node_log_read.py`) interpret
+them.
+
+Decoding server-side means the record layout is defined in two places — C and
+Rust — and can drift silently. The pilot already paid for a version of this:
+a field whose sentinel the host had to learn to render as `n/a`, where a
+plausible wrong value would have been worse than an obvious gap. That argues
+for the raw proxy and a single definition of the format.
+
+## Non-goals
+
+Real-time monitoring, log streaming, fleet-wide log aggregation, and alerting
+on log contents are all explicitly out of scope. If a future need genuinely
+requires one of them, it should revisit this ADR rather than grow into it.
@@ -0,0 +1,93 @@
+# ADR 363: Native macOS USB node onboarding
+
+## Status
+
+Accepted and physically qualified with one attached ESP32 S3 and one attached
+ESP32 C6 through an unsigned Mac Catalyst development build. Signed
+distribution remains a release gate.
+
+## Context
+
+RuView operators currently provision ESP32 nodes with command line tooling.
+The macOS app can list server accepted node identities, but it cannot establish
+that an attached serial device is RuView firmware, assign a collision free node
+identity, preserve its WiFi configuration, or prove that it joined the sensing
+server. A UI that merely stores a friendly name would create false success.
+
+Generic shell access from the app would also expand authority beyond the task.
+Serial logs can contain operational data, and WiFi credentials must not enter
+application diagnostics or provisioning receipts.
+
+## Decision
+
+1. Firmware 0.8.12 provides a bounded line protocol over the physical USB serial
+   channel. A discovery request carries a random 128 bit nonce. The device
+   response binds that nonce to chip family, firmware version, current node
+   identity, private server target, configuration state, and a pseudonymous
+   64 bit device digest derived from the base MAC under a RuView domain.
+
+2. A configuration request is accepted only for the most recently issued
+   nonce within 60 seconds. The nonce is single use. Node identity is limited
+   to 1 through 255, the target is limited to RFC 1918 IPv4, and the target port
+   is limited to 1 through 65535.
+
+3. Existing WiFi configuration can be preserved. New credentials use strict
+   base64 framing, bounded lengths, and control character rejection. Firmware
+   commits NVS before acknowledging and rebooting. Credentials are never
+   returned, logged, or included in the receipt.
+
+4. The macOS client uses a native serial bridge. It allowlists exact character
+   device prefixes, configures the port directly, and does not invoke a shell,
+   Python, or an external process. It rechecks the device digest immediately
+   before configuration to reduce port substitution risk.
+
+5. The app suggests the lowest unused server node identity and the Mac private
+   LAN address. Success is shown only after the configured node appears in the
+   server inventory as active with evidence no older than three seconds.
+
+6. Old firmware is reported as requiring an update. The app must not claim it
+   provisioned a device based only on generic RuView serial logs.
+
+7. Automatic firmware flashing is outside this decision. Flashing requires an
+   exact chip and port check, a private backup, a matching image, and captured
+   boot evidence. Release publication remains a separate maintainer action.
+
+8. The device digest uses the PSA Crypto SHA 256 interface on ESP IDF 5.4 and
+   6.0. This keeps the stable domain separated identity while avoiding the
+   legacy Mbed TLS hash API removed by ESP IDF 6.
+
+9. ESP32 C6 mmWave UART defaults use GPIO 4 and GPIO 5. Startup rejects any
+   configured mmWave pin pair that overlaps the active console RX or TX pins.
+   This preserves the onboarding input path after a failed mmWave probe.
+
+## Security and privacy consequences
+
+The app gains Mac App Sandbox USB and serial device access, but not general file
+or shell authority. The protocol does not authenticate a device with a hardware
+root of trust; the digest is stable identification, not a cryptographic device
+certificate. Physical USB possession is therefore the trust boundary for this
+version. An authenticated fleet identity remains ADR 305 scope.
+
+The largest failure mode is a successful NVS write followed by failure to join
+the LAN. The user receives an explicit bounded verification failure instead of
+a success screen, while the board retains its committed settings and can be
+rescanned over USB.
+
+## Acceptance test
+
+Connect an ESP32 with firmware 0.8.12 to a Mac that is already receiving RuView
+nodes. Use only the macOS Add Sensor workflow to preserve WiFi, assign the
+lowest unused identity, and set the Mac private address. Pass when the UI
+reports the expected chip and firmware, the reassigned node remains fresh for
+five minutes, the stale collided identity expires, app restart preserves the
+profile, no server health, send, watchdog, panic, or reboot evidence appears,
+and no credential appears in app logs or the provisioning receipt.
+
+The 2026-08-31 physical run passed on an ESP32 S3. The measured witness is in
+`docs/validation/2026-08-31-macos-usb-node-onboarding.md`.
+
+The 2026-09-11 physical run passed on an ESP32 C6 over
+`cu.usbserial-3120`. The Mac app flashed the image, received the nonce bound
+hello receipt, preserved node identity 3, committed the server route, and
+verified fresh server evidence at minus 34 dBm. The run also exposed and fixed
+the GPIO 17 console RX conflict described above.
@@ -92,10 +92,13 @@ Statuses: **Proposed** (under discussion), **Accepted** (approved and/or impleme
 | [ADR-150](ADR-150-rf-foundation-encoder.md) | RF Foundation Encoder: pose-preserving, subject/room/device-invariant CSI embedding | Proposed |
 | [ADR-151](ADR-151-room-calibration-specialist-training.md) | Per-Room Calibration & Specialized Model Training (room-first → bank of small ruVector specialists) | Proposed |
 | [ADR-152](ADR-152-wifi-pose-sota-2026-intake.md) | WiFi-Pose SOTA 2026 Intake: geometry-conditioned calibration, external benchmarks, foundation-encoder recipe | Proposed |
+| [ADR-345](ADR-345-per-link-csi-and-node-to-node-ranging.md) | Per-link CSI attribution and node-to-node ranging — why phase-based position fails on this hardware (measured), and the coordination-free `(tx_mac, rx_seq)` join key that does not need it | Proposed — measurement layer implemented and validated on hardware; localization not built |
 | [ADR-348](ADR-348-independent-rust-multivariate-forecasting.md) | Independent Rust multivariate forecasting for RuView | Proposed |
 | [ADR-349](ADR-349-governed-local-and-fal-forecast-training.md) | Governed local and fal.ai forecast training | Proposed |
 | [ADR-350](ADR-350-ruvector-predictive-memory-and-ruvllm-boundary.md) | RuVector predictive memory and RuVLLM authority boundary | Proposed |
 | [ADR-354](ADR-354-forecast-governance-enforcement-in-ruforecast-submodule.md) | fal.ai forecast governance and spend enforcement now real, in the vendored RuForecast submodule | Accepted |
+| [ADR-355](ADR-355-local-empty-room-bootstrap-prior.md) | Local empty room bootstrap prior | Accepted |
+| [ADR-356](ADR-356-rate-truthful-csi-and-reliability-gated-adaptation.md) | Rate truthful CSI and reliability gated room adaptation | Accepted |

 ### Platform and UI

@@ -112,6 +115,7 @@ Statuses: **Proposed** (under discussion), **Accepted** (approved and/or impleme
 | [ADR-344](ADR-344-adaptive-local-installation-discovery.md) | Adaptive Local Installation Discovery | Accepted (local software path) |
 | [ADR-346](ADR-346-fail-closed-edge-occupancy-evidence.md) | Fail closed ESP32 occupancy evidence | Accepted (C6 occupancy integrity qualified) |
 | [ADR-347](ADR-347-rate-aware-esp32-temporal-sensing.md) | Rate aware ESP32 temporal sensing | Accepted (C6 timing and transport qualified) |
+| [ADR-363](ADR-363-native-macos-usb-node-onboarding.md) | Native macOS USB node onboarding with nonce bound discovery and fresh server verification | Accepted and physically qualified on one ESP32 S3; C6 and signed distribution pending |
 | [ADR-115](ADR-115-home-assistant-integration.md) | Home Assistant integration via MQTT auto-discovery + Matter bridge (HA-DISCO + HA-FABRIC + HA-MIND) | Accepted (MQTT track) / Proposed (Matter SDK P8b) |
 | [ADR-169](ADR-169-adam-mode-light-theme.md) | adam-mode — light theme toggle for the three.js realtime demo | Proposed |
 | [ADR-170](ADR-170-yoga-mode-pose-system.md) | yoga-mode — yoga pose detection, classification, and scoring for the three.js realtime demo | Proposed |
@@ -0,0 +1,165 @@
+# Which CSI frames a node keeps decides whether cross-node fusion works
+
+A measured comparison of three frame-selection gates on a nine-node ESP32-C6
+fleet, and a method for repeating it in your own environment.
+
+**This is one house.** Nine boards, one floor plan, one RF environment, one
+transmitter population. The numbers below are what we measured here; the part
+worth reusing is the method, not our figures. `run_arms.py` is included so you
+can measure yours.
+
+---
+
+## The problem
+
+Cross-node fusion pairs frames by transmission identity: two nodes are fusing
+usefully only when they hold measurements of *the same packet in the air*. The
+metric is `paired_fraction` — of the transmissions the fleet reported, what
+share were captured by two or more nodes.
+
+Every node also rate-limits which CSI callbacks it keeps, because processing
+every callback at 100–500 Hz destabilises the WiFi ISR. **How that limiting is
+done turns out to matter far more than we expected**, because it decides
+whether two nodes keep the *same* frames or merely the *same number* of frames.
+
+Three mechanisms, all valid rate limits:
+
+| gate | rule |
+|---|---|
+| `elapsed` | at least 20 ms since **this node's** last accepted frame |
+| `mesh` | first frame heard in each shared 20 ms window of a mesh-aligned clock |
+| `seq` | keep frames where the 802.11 `rx_seq` is divisible by N |
+
+`elapsed` gives every node an independent phase. `mesh` makes nodes agree on
+the *window*. `seq` makes them agree on the *frame*, using a number the
+transmitter assigns — so it needs no clock, no leader and no synchronisation.
+
+## Method
+
+Four arms — the three gates plus `mesh`+`seq` stacked — run as a 2x2 factorial.
+Three deliberate choices, each of which we got wrong first:
+
+**Whole fleet per arm, never a subset.** An earlier attempt compared four gated
+nodes against four ungated ones. Nodes differ enormously in how much traffic
+they hear, so that comparison could not be read at all.
+
+**Verify the gate is actually running.** Each switch is read back from every
+node before sampling. "Config was stored" is not "gate is live", and an earlier
+run could not distinguish a null result from a change that never applied.
+
+**Frame rate is NOT a valid check that a gate is working.** A bucket gate needs
+only one survivor per window, so at ~14 candidate frames per bucket even a
+perfect 1-in-4 gate moves frame rate about 2%. Use instead
+
+    R_window = (delta early_drop + delta accepted) / delta accepted
+
+computed from **differenced** counters. Never divide lifetime totals: they
+carry a large post-boot burst. One node read R = 1126 moments after a reboot,
+26.5 an hour later, and 19.2 windowed.
+
+**Establish the noise floor first.** A null run — three hours, no changes —
+gave drift of sd **0.45 pp** across 20-minute windows, about 2x the ±0.2 pp
+binomial counting error. Without that number none of the results below can be
+called significant.
+
+Arms are 20 minutes in Latin-square blocks (`U M S MS / S MS M U / MS U S M`),
+so slow drift lands on every arm equally rather than on whichever ran first.
+
+## Results
+
+Three blocks, twelve arms, every arm verified live on all nine nodes.
+
+| arm | block 0 | block 1 | block 2 | mean |
+|---|---|---|---|---|
+| `elapsed` | 0.2881 | 0.2409 | 0.2012 | **0.2434** |
+| `mesh` | 0.2692 | 0.2580 | 0.2167 | **0.2480** |
+| `seq` (period 8) | 0.5819 | 0.5573 | 0.5422 | **0.5605** |
+| `mesh`+`seq` | 0.5639 | 0.5623 | 0.5093 | 0.5452 |
+
+**`seq` roughly doubles pairing: +31.7 pp, 2.30x.** That gap is ~70x the
+measured drift floor and reproduces in all three blocks; within-block contrasts
+sit at +0.153 to +0.175 every time.
+
+**Mesh-time alignment bought essentially nothing here: +0.5 pp**, about one
+standard deviation of the noise floor. We built that gate and expected it to be
+the answer; it is indistinguishable from doing nothing. Stacking it on top of
+`seq` is marginally *worse* than `seq` alone.
+
+### It is a trade, not a free win
+
+At period 8 the seq arms carried ~75–95k transmissions per 20 minutes against
+~120–160k ungated. You are buying pairing with raw frame rate. Absolute paired
+transmissions per minute still went **up** (2629 vs 2524), because the frames
+it discards are disproportionately ones only one node would have kept — but
+whether that trade is right depends on what else consumes the stream.
+
+One measurement that made the trade easier here: on-device edge processing was
+**unaffected**. Frames actually processed stayed ~1900 per node per 4 minutes
+in both modes, because that pipeline is separately rate-limited. The cost falls
+on the uplink, not on local sensing.
+
+### The mesh arm was partly an elapsed arm
+
+The mesh gate uses mesh-time buckets only while `c6_sync_espnow_is_valid()`. A
+node without valid sync falls back to the elapsed gate rather than gating on a
+meaningless epoch -- correct behaviour, but it weakens this comparison.
+
+Three of the nine nodes never synchronised during these runs. For those three,
+the `mesh` and `mesh`+`seq` arms silently ran the elapsed gate. So **+0.5 pp is
+not a clean fleet-wide measurement of window alignment**; it is "mesh where sync
+held, elapsed where it did not", and the true effect of alignment on a fully
+synchronised fleet is not measured here.
+
+We are reporting the number as observed rather than reconstructing it, because
+the arms were assigned before we understood the fallback, and a post-hoc
+per-node reanalysis would not be the experiment we ran.
+
+The cause is worth naming because it is environmental, not a firmware defect.
+Time sync is leader-elected and hub-and-spoke: one node broadcasts and the rest
+follow. Whether every node hears that leader is a property of the building. A
+larger or more divided house fragments into sync domains, and any option that
+depends on shared time then degrades quietly for the nodes that fell out --
+which is precisely the situation where someone would most want to trust this
+measurement.
+
+### A prediction we got wrong
+
+Our mesh had split into two leader domains with three nodes never synchronising
+at all. We predicted `seq` would win *most* on node pairs spanning that split.
+Per-pair yield says otherwise:
+
+| pair group | pairs | seq / mesh |
+|---|---|---|
+| same sync domain | 7 | 5.82x |
+| spans the two domains | 8 | 6.24x |
+| involves a never-synced node | 21 | **5.16x** |
+
+Cross-domain is marginally best, but the never-synced nodes are the *lowest* —
+the opposite of the prediction — and within-group spread (3.6x–8.1x) dwarfs
+every between-group difference.
+
+So `seq` is **not** a workaround for broken time sync. It wins roughly
+uniformly, including where sync is healthy. The useful consequence is negative:
+repairing our mesh split would probably not have closed the gap, and we would
+have spent that effort for nothing.
+
+## What we suggest
+
+Not "use `seq`". **Make it selectable and measure your own environment.** The
+right answer depends on your transmitter population, your node placement and
+what consumes your CSI stream — none of which we can see from here.
+
+`run_arms.py` runs the factorial unattended: it applies each arm fleet-wide,
+verifies every node adopted it, samples `/api/v1/fusion`, and writes one row
+per arm. Run the null pass first; without your own drift floor the contrasts
+cannot be judged.
+
+## Limits
+
+- One environment, nine nodes. Treat the numbers as an existence proof, not a
+  constant.
+- Only period 8 was characterised. 4 and 16 are unmeasured, so the
+  yield/pairing curve has a single point on it.
+- `paired_fraction` measures **frame pairing**, which is a precondition for
+  cross-receiver work. Nothing here measures sensing accuracy, and none of it
+  should be read as an accuracy claim.
@@ -81,6 +81,42 @@ v1, with its flat loss, was barely better than random on this same test.
 params, trained with InfoNCE (temperature 0.1, in-batch + temporal-far negatives), AdamW, 60 epochs.
 Temporal positives within 2 s; negatives >30 s apart. Time-disjoint 80/20 split.

+**EWC (catastrophic-forgetting protection):** measured forgetting rate on the 4 protected
+tasks is **32.97%** — real and non-trivial, disclosed here rather than only in the raw
+`training-metrics.json`. Fisher information is computed and applied (protection strength
+2000), but this is not "solved forgetting" — a user fine-tuning per-room LoRA adapters
+should expect some drift on earlier tasks, not none.
+
+## 🔧 v2.0.1 — fixed the published training-metrics.json itself (2026-09-09)
+
+Separately from the v1→v2 accuracy retraction above, an unrelated bug was found and fixed
+in the **export code** (`scripts/train-ruvllm.js`) that produces `config.json` and
+`training-metrics.json` for this file set (`model.safetensors`, `model-q2/q4/q8.bin`,
+`presence-head.json`, `node-1/2.json`) — separate from the `csi-embed-v2*` files, which
+come from a different script.
+
+The exported `lossHistory` and `contrastive.durationMs` were being read from a disconnected
+baseline pass (`ContrastiveTrainer.train()`, which computes loss but never updates the
+encoder) instead of from the loop that actually performs gradient updates on the encoder
+weights. Concretely: `lossHistory` published a flat, non-decreasing curve around `0.1352`
+for all 20 epochs, and `durationMs` reported ~12.4s — both measuring the wrong computation.
+
+**This did not affect `finalLoss`/`improvement`/the 82.3% held-out temporal-triplet
+accuracy above** — those were already computed from the real training loop and are
+unchanged by this fix. It only affected the exported diagnostic curve and duration, which
+anyone auditing convergence from the published JSON would have been misled by. Re-run
+against the same real capture (`data/recordings/overnight-1775217646.csi.jsonl`) with the
+fix applied: `lossHistory` now shows a genuine decreasing curve (0.1037 -> 0.0654 across 20
+epochs) and `durationMs` reports the real ~40s gradient-loop time. `config.json`'s
+`training.steps` field (`12212300` — epochs × triplets, arithmetically consistent but read
+like optimizer-step count) is now reported as separate `epochs`/`tripletUpdatesPerEpoch`
+fields instead.
+
+Repro: `node scripts/train-ruvllm.js --data data/recordings/overnight-1775217646.csi.jsonl
+--output <dir> --epochs 20` in [github.com/ruvnet/RuView](https://github.com/ruvnet/RuView)
+(the `aether-arena/staging/train_csi_embed.py` path cited above is for the separate
+`csi-embed-v2*` files and was not touched by this fix).
+
 ### v2 files & proof
 | File | Size | Use |
 |------|------|-----|
@@ -0,0 +1,10 @@
+ARM_A1_control,30,1242,2162,0.5745,72.07
+ARM_A1_control,30,1199,2114,0.5672,70.47
+ARM_A1_control,30,1259,2223,0.5664,74.10
+ARM_A1_control,30,1221,2206,0.5535,73.53
+ARM_A1_control,30,1246,2182,0.5710,72.73
+ARM_A1_control,30,1295,2247,0.5763,74.90
+ARM_A1_control,30,1307,2242,0.5830,74.73
+ARM_A1_control,30,1232,2191,0.5623,73.03
+ARM_A1_control,30,1261,2225,0.5667,74.17
+ARM_A1_control,30,1152,2107,0.5467,70.23
@@ -0,0 +1,10 @@
+ARM_A2_control,30,1352,2326,0.5813,77.53
+ARM_A2_control,30,1454,2429,0.5986,80.97
+ARM_A2_control,30,1474,2479,0.5946,82.63
+ARM_A2_control,30,1412,2456,0.5749,81.87
+ARM_A2_control,30,1387,2443,0.5677,81.43
+ARM_A2_control,30,1389,2384,0.5826,79.47
+ARM_A2_control,30,1399,2482,0.5637,82.73
+ARM_A2_control,30,1410,2375,0.5937,79.17
+ARM_A2_control,30,1509,2537,0.5948,84.57
+ARM_A2_control,30,1483,2541,0.5836,84.70
@@ -0,0 +1,10 @@
+ARM_B_filtered,30,734,1062,0.6911,35.40
+ARM_B_filtered,30,700,982,0.7128,32.73
+ARM_B_filtered,30,734,1002,0.7325,33.40
+ARM_B_filtered,30,706,927,0.7616,30.90
+ARM_B_filtered,30,730,955,0.7644,31.83
+ARM_B_filtered,30,712,915,0.7781,30.50
+ARM_B_filtered,30,734,971,0.7559,32.37
+ARM_B_filtered,30,742,1103,0.6727,36.77
+ARM_B_filtered,30,812,1139,0.7129,37.97
+ARM_B_filtered,30,785,1114,0.7047,37.13
@@ -0,0 +1,63 @@
+# WiFlow Reproduction Protocol
+
+Status: Proposed research protocol
+
+Tracks issue #1786.
+
+## Objective
+
+Determine whether a CSI optical flow style representation improves reusable camera free motion intelligence in RuView rather than only improving a proxy flow metric.
+
+## Required capture metadata
+
+Every run records hardware family, firmware, antenna count and geometry, channel width, center frequency, packet rate, timestamp source, synchronization method, room identity, participant identity class, label source, calibration, packet loss, missing subcarriers, preprocessing version, model commit, accelerator, software versions, power mode, and random seeds.
+
+## Baselines
+
+1. current RuView CSI preprocessing plus strongest task specific sensing head
+2. WiFlow style motion field representation
+3. simpler temporal derivative or phase and amplitude motion baseline
+
+All conditions use identical train, validation, and held out environment splits.
+
+## Metrics
+
+Primary intermediate metrics:
+
+* endpoint error or equivalent flow error
+* directional consistency
+* temporal stability
+* uncertainty calibration
+
+Required downstream metrics:
+
+* tracking quality
+* occupancy or presence quality
+* pose or activity metric where available
+* spatial state consistency in RuField or WorldGraph
+
+Systems metrics:
+
+* p50 and p95 inference latency
+* peak memory
+* CPU, GPU, or accelerator utilization
+* energy per inference where measurable
+* bytes per observation and sustained bandwidth
+
+## Stress tests
+
+Test unseen rooms, unseen participants, changed antenna geometry, a second RF hardware family, packet loss, burst loss, missing subcarriers, lower packet rate, clock jitter, and partial calibration failure.
+
+## Promotion gate
+
+The representation graduates only when the same learned representation improves at least two downstream RuView tasks on held out environments, or reaches equivalent downstream quality with materially lower edge cost.
+
+A better optical flow proxy score alone is insufficient.
+
+## Security and privacy
+
+Visual or LiDAR labels may be used as privileged training evidence but must not become a runtime dependency for camera free deployment claims. Dataset provenance and consent requirements remain explicit.
+
+## Rollback
+
+The experiment is isolated behind a representation interface. Existing RuView sensing heads remain the production fallback.
@@ -0,0 +1,60 @@
+# Native macOS USB onboarding firmware witness
+
+## Evidence class
+
+MEASURED on 2026-08-31 with one physical ESP32 S3. This is not an ESP32 C6 or
+release distribution qualification.
+
+## Hardware and firmware
+
+The board was identified by the flashing tool as ESP32 S3 QFN56 revision 0.2
+with 2 MB embedded PSRAM and 8 MB flash. Firmware 0.8.9 was built for ESP32 S3
+with the displayless DevKitC defaults. The private configuration region was
+backed up before flashing. The flash operation omitted NVS, preserving the
+existing WiFi configuration.
+
+No base MAC, WiFi credential, device digest, or raw CSI is retained in this
+witness.
+
+## Results
+
+1. The initial native USB scan failed because the ESP-IDF secondary USB
+   Serial/JTAG console mirrors output but does not forward input to STDIN.
+2. Firmware was corrected to read the bounded onboarding protocol from the
+   secondary VFS while retaining STDIN for UART console boards.
+3. A direct nonce challenge then returned ESP32 S3, firmware 0.8.9, configured
+   state, the current node identity, and the private server route.
+4. The Mac app changed the collided identity from 1 to unused identity 5 while
+   preserving WiFi. It showed success only after receiving fresh server
+   evidence at minus 56 dBm.
+5. A five minute monitor collected 299 samples with zero node 5 missing events,
+   zero node 5 stale events, zero server health failures, minus 57 to minus 50
+   dBm RSSI, and 216 ms maximum packet age.
+6. Firmware uptime exceeded 376 seconds. Captured logs advanced from CSI
+   callback 10,600 through 11,000, emitted a node 5 synchronization packet, and
+   showed ESP NOW transmit failures equal to zero without reboot, watchdog, or
+   panic evidence.
+7. The final channel isolation hardening image was flashed and challenged
+   again. A following 60 sample check had zero missing, stale, or health failure
+   events, a maximum packet age of 100 ms, and minus 57 to minus 50 dBm RSSI.
+
+## Software gates
+
+The nonce and configuration parser host test passed, the complete ESP32 S3
+firmware image built under ESP-IDF 5.4, and the application image occupied
+941,056 bytes with 55 percent of the smallest application partition free.
+
+## Remaining gates
+
+New WiFi credential entry, signed Mac distribution, and cross platform serial
+bridges remain unmeasured.
+
+## ESP32 C6 follow up
+
+On 2026-09-11, an ESP32 C6 on `cu.usbserial-3120` completed the Mac app flash,
+hello, configure, and verify sequence with firmware 0.8.12. The app preserved
+the existing node identity 3 and verified fresh sensing server evidence at
+minus 34 dBm. The board returned `RUVIEW_HELLO_OK_V1` within the bounded serial
+exchange after the C6 mmWave defaults moved from the UART0 RX conflict on GPIO
+17 to GPIO 4 and GPIO 5. This closes only the physical C6 onboarding gate. It
+does not qualify new WiFi credential entry or signed distribution.
@@ -19,6 +19,25 @@ This firmware captures WiFi Channel State Information (CSI) from an ESP32-S3 (pr
 > | **Fall detection** | Phase acceleration threshold | Configurable sensitivity |
 > | **Programmable sensing** | WASM modules loaded over HTTP | Hot-swap, no reflash |

+## Firmware 0.8.12: guided Mac onboarding
+
+Firmware 0.8.12 adds the protocol used by the RuView macOS Add
+Sensor workflow. A directly attached S3 or C6 can identify itself through a
+nonce bound USB serial receipt, preserve its current WiFi settings, accept an
+unused node ID and private LAN server address, then reboot. The Mac app does
+not report success until the sensing server observes that node as fresh.
+
+This is not a firmware flashing API. A board on 0.8.8 or earlier must receive a
+matching chip build through the documented backup and flash process once. The
+USB protocol rejects public target addresses and invalid identifiers. New WiFi
+credentials are bounded, committed only in NVS, and never included in the
+receipt or diagnostic output. See
+[ADR 363](../../docs/adr/ADR-363-native-macos-usb-node-onboarding.md).
+
+On ESP32 C6, the default optional mmWave UART uses GPIO 4 and GPIO 5. Firmware
+refuses any mmWave configuration that overlaps the active console pins. This
+prevents a sensor probe from taking over UART0 RX and disabling Mac onboarding.
+
 ## Firmware 0.8.8 in plain language

 Release 0.8.8 makes the sensing stream more internally consistent and easier
@@ -115,6 +134,30 @@ python -m esptool --chip esp32s3 --port COM7 --baud 460800 \
  0x20000 firmware/esp32-csi-node/build/esp32-csi-node.bin
 ```

+#### Seeed XIAO ESP32-C6 external antenna
+
+The XIAO ESP32-C6 has a hardware RF switch between its internal ceramic
+antenna and U.FL connector. Generic C6 boards do not share this wiring, so the
+firmware leaves GPIO3 and GPIO14 untouched by default. For an XIAO with an
+external antenna already attached while powered off, build with one of the
+opt-in overlays:
+
+```bash
+# Controlled A condition: internal antenna, RF path stated in the boot log.
+idf.py -D SDKCONFIG_DEFAULTS="sdkconfig.defaults;sdkconfig.defaults.esp32c6;sdkconfig.defaults.xiao-internal" \
+  set-target esp32c6
+idf.py build
+
+# Controlled B condition: external U.FL antenna.
+idf.py -D SDKCONFIG_DEFAULTS="sdkconfig.defaults;sdkconfig.defaults.esp32c6;sdkconfig.defaults.xiao-external" \
+  set-target esp32c6
+idf.py build
+```
+
+The boot log must report the intended `internal ceramic` or `external U.FL`
+path before that measurement is labelled. The standard C6 build keeps the
+board default and emits no antenna-path claim.
+
 ### 3. Provision WiFi credentials (no reflash needed)

 ```bash
@@ -257,10 +300,17 @@ Offset  Size  Field
 12      4     Sequence number (LE u32)
 16      1     RSSI (i8)
 17      1     Noise floor (i8)
-18      2     Reserved
+18      1     PPDU type (ADR-110; zero when tagging is disabled)
+19      1     Flags: bit0=40 MHz, bit2=STBC, bit4=sync valid,
+              bit5=invalid first CSI word zeroed by firmware
 20      N*2   I/Q pairs (n_antennas * n_subcarriers * 2 bytes)
 ```

+When ESP-IDF marks `first_word_invalid`, the firmware preserves packet geometry,
+zeros the first four CSI bytes, and sets byte 19 bit 5. The same sanitized bytes
+feed the edge DSP path. This prevents a documented hardware artifact from being
+learned as motion while keeping older readers wire compatible.
+
 ### Vitals Packet (32 bytes)

 ```
@@ -0,0 +1,334 @@
+# Firmware runbook — ESP32-C6 CSI node
+
+Operational procedure. `README.md` explains the project; this says exactly what
+to run, in what order, and what to check. Follow it top to bottom.
+
+If you are an agent: **read this file before touching firmware.** Everything
+below was learned by getting it wrong at least once.
+
+---
+
+## 1. Build
+
+**One command. Copy it.** From the **repository root**, not this directory:
+
+```bash
+MSYS_NO_PATHCONV=1 docker run --rm \
+  -v "$(pwd)/firmware/esp32-csi-node:/project" -w /project \
+  espressif/idf:v5.4 bash -c \
+  "cat sdkconfig.defaults sdkconfig.defaults.16mb sdkconfig.defaults.esp32c6 \
+     > sdkconfig.defaults.build && \
+   SDKCONFIG_DEFAULTS='sdkconfig.defaults.build' idf.py set-target esp32c6 && \
+   idf.py build"
+```
+
+Takes ~3 minutes cold, well under a minute incremental.
+
+### The three defaults files are NOT all automatic
+
+IDF picks up `sdkconfig.defaults` and `sdkconfig.defaults.<target>` on its own.
+It does **not** pick up `sdkconfig.defaults.16mb`, and that file is where
+`CONFIG_BOOTLOADER_APP_ROLLBACK_ENABLE=y` lives.
+
+Build without it and you get an image that is correct in every visible respect
+and **cannot roll back a bad OTA** — while `ota_rollback_boot_check()` sits in
+the app expecting the capability. Silent, and only discoverable by pushing a
+deliberately bad image.
+
+That is why the command above concatenates all three explicitly rather than
+relying on discovery.
+
+### Never `rm -rf sdkconfig` without a backup
+
+The README's headline example opens with `rm -rf build sdkconfig`. `sdkconfig`
+is **untracked and gitignored**. `partitions_16mb.csv` was lost to exactly this,
+and `CLAUDE.md` warns about it *even when a README documents it*.
+
+```bash
+cp sdkconfig "sdkconfig.backup-$(date +%Y%m%d-%H%M%S)"   # then regenerate
+```
+
+A stale `sdkconfig` is a real hazard, not a hypothetical: one found on
+2026-09-03 said `FLASHSIZE=4MB`, `partitions_4mb.csv`,
+`DYNAMIC_TX_BUFFER_NUM=64` — against a fleet running 16MB and 128. Anything
+built from it would silently not be the configuration under test.
+
+### Verify before you flash anything
+
+```bash
+grep -E "^CONFIG_(IDF_TARGET|ESPTOOLPY_FLASHSIZE|PARTITION_TABLE_CUSTOM_FILENAME|\
+ESP_WIFI_DYNAMIC_TX_BUFFER_NUM|BOOTLOADER_APP_ROLLBACK_ENABLE)=" sdkconfig
+```
+
+All five must read:
+
+| key | expected |
+|---|---|
+| `CONFIG_IDF_TARGET` | `"esp32c6"` |
+| `CONFIG_ESPTOOLPY_FLASHSIZE` | `"16MB"` |
+| `CONFIG_PARTITION_TABLE_CUSTOM_FILENAME` | `"partitions_16mb.csv"` |
+| `CONFIG_ESP_WIFI_DYNAMIC_TX_BUFFER_NUM` | `128` |
+| `CONFIG_BOOTLOADER_APP_ROLLBACK_ENABLE` | `y` |
+
+**Do not use the native `C:\Espressif\...esp-idf-v5.5.5`.** Wrong version, its
+venv does not match the default python, and a container-built `build/` refuses
+a native build outright. Docker only.
+
+---
+
+## 2. What OTA can and cannot reach
+
+This is the distinction that decides whether a change needs a cable.
+
+| region | offset | reachable by OTA? |
+|---|---|---|
+| bootloader | `0x0` | **NO — USB only** |
+| partition table | `0x8000` | **NO — USB only** |
+| otadata | `0xF000` | rewritten by OTA |
+| ota_0 | `0x20000` | yes (4 MB) |
+| ota_1 | `0x420000` | yes (4 MB) |
+| coredump | `0x820000` | no |
+| storage (fat) | `0x830000` | no |
+| nvs | `0x9000` | never written by a flash — provisioning survives |
+
+**OTA replaces the app partition only.** Anything in the bootloader —
+`CONFIG_BOOTLOADER_*`, notably `APP_ROLLBACK_ENABLE` — or any partition-table
+change **requires USB on every board**.
+
+There is **no bootloader version on the wire**. A node's sync packet reports app
+health, not bootloader capability, so you cannot determine remotely which boards
+have a rollback-capable bootloader. Track it per board, or do a USB pass across
+all of them.
+
+Corollary: "every node reports health" proves the **app** is current and proves
+nothing about the bootloader. Do not answer a bootloader question with app
+evidence.
+
+---
+
+## 3. Deploying
+
+### Over the air — app-only changes
+
+Works end-to-end and is the default for anything that is not a bootloader or
+partition change. Roll to **one node**, soak it, then the rest.
+
+### Over USB — bootloader, partition table, or recovery
+
+```bash
+python -m esptool --chip esp32c6 -b 460800 \
+  --before default_reset --after hard_reset write_flash \
+  --flash_mode dio --flash_size 16MB --flash_freq 80m \
+  0x0     build/bootloader/bootloader.bin \
+  0x8000  build/partition_table/partition-table.bin \
+  0xf000  build/ota_data_initial.bin \
+  0x20000 build/esp32-csi-node.bin
+```
+
+`0x9000` is not in that list, so SSID, password and `node_id` survive.
+
+### Safe single-board diagnostic flash, with a revert path
+
+Nodes run from whichever slot `otadata` selects. **Parse it before flashing** —
+two 32-byte entries at offsets 0 and 0x1000; active slot is
+`(max ota_seq - 1) % 2`.
+
+1. Back up `otadata` (8 KB) **and** the live app slot with `esptool read-flash`.
+2. Flash the diagnostic build — it lands in `ota_0` and rewrites `otadata`.
+3. **Revert = write the 8 KB `otadata` backup back.** Production in `ota_1` was
+   never touched, so no rebuild is needed.
+
+Validate any backup image before trusting it: byte 0 must be `0xE9`, and the
+`esp_app_desc_t` magic at offset `0x20` must be `0xABCD5432`.
+
+**Never flash the whole fleet from a workstation, and never use the server's OTA
+endpoint for a diagnostic.** USB, one board, revert path secured first.
+
+---
+
+## 4. Serial
+
+CH343 USB-serial at 115200.
+
+To read a running board **without resetting it**, open with
+`DtrEnable=$false; RtsEnable=$false`. esptool asserts RTS and *will* reset the
+board, which loses the state you were trying to observe.
+
+---
+
+## 5. Changing config without a cable
+
+Most parameters do not need a flash at all:
+
+```bash
+export RUVIEW_OTA_PSK_FILE=<path to the psk file>       # never inline the key
+python config_push.py --node <node-ip> --get
+python config_push.py --node <node-ip> --set led_brightness=10
+```
+
+Keys marked `assoc: true` in `config_api.c` (`wifi_ssid`, `wifi_password`,
+`channel_hop_count`, `dwell_ms`, `csi_channel`) are applied as a **trial**: the
+node banks its current values, reboots, and keeps the change only if it
+re-associates. Everything else applies without that risk.
+
+`config_push.py` has **no unset**. To restore a default you must set it
+explicitly. Current defaults:
+
+| key | default | source |
+|---|---|---|
+| `vital_interval_ms` | 1000 | `Kconfig.projbuild` |
+| `swarm_heartbeat_sec` | 30 | `nvs_config.c` |
+| `swarm_ingest_sec` | 5 | `nvs_config.c` |
+| `beacon_period_ms` | 0 = derive from fleet size | `nvs_config.c` |
+
+---
+
+## 6. Reading a node remotely
+
+`GET /api/v1/mesh` returns per-node `health`: `min_heap_kib`, `die_c`,
+`thermal_state`, `tx_dbm`, `reset_reason`, and from sync proto v3 the TX-path
+counters `send_fail` / `rate_skip` / `early_drop`.
+
+`min_heap_kib` is a **minimum-since-boot watermark**, not an instantaneous
+reading. It resets on reboot and only ever falls. Sampling it within a minute of
+a restart tells you nothing — that mistake produced a wrong "no effect" verdict
+on 2026-09-03; the real answer, once it had settled, was −56 KiB.
+
+`/api/v1/nodes` `rssi_dbm` is **not** the AP link — it is whatever link landed
+most recently and swings 20+ dB with no physical change. Filter `/api/v1/links`
+by the AP's BSSIDs instead, and read `csi_fps_ema` alongside, because link count
+alone hides a starved node.
+
+---
+
+## 7. Tunables, and which ones depend on your house
+
+`idf.py menuconfig` exposes these. The defaults are what a nine-node ESP32-C6
+fleet in one house settled on; several are **not** universal, and the point of
+listing them here is that you can pick and measure rather than inherit someone
+else's building.
+
+| option | default | depends on your house? |
+|---|---|---|
+| `CSI_GATE_MESH_ALIGNED` | y | **yes** |
+| `CSI_SEQ_DIAG` | n | diagnostic only |
+| `THERMAL_MONITOR` | y | no |
+| `THERMAL_THROTTLE` | n | **yes** |
+| `THERMAL_THROTTLE_C` | 72 | **yes** |
+| `THERMAL_HYSTERESIS_C` | 8 | no |
+| `UPLINK_WATCHDOG` | y | no |
+| `UPLINK_WATCHDOG_TIMEOUT_S` | 1200 | **yes** |
+
+### The ones worth measuring yourself
+
+**`CSI_GATE_MESH_ALIGNED`** decides whether nodes keep the *same* frames or
+merely the same *number* of frames, which is what makes cross-node pairing
+possible at all. Whether alignment helps depends on how much your nodes
+actually overhear in common, and that is a property of your walls and your
+transmitters. In one measured nine-node fleet, aligning windows bought
+0.5 pp of pairing while selecting frames by `rx_seq` bought +31.7 pp -- so do
+not assume the default is doing the heavy lifting in your building.
+
+Turn on `CSI_SEQ_DIAG` to measure it. It logs `(source MAC, rx_seq)` per CSI
+callback, which is what lets you compute the fraction of frames two nodes hold
+in common instead of guessing.
+
+**`THERMAL_THROTTLE` / `THERMAL_THROTTLE_C`** depend on enclosure and placement,
+not on the chip. A bare bench board never reaches 72 C; the same board sealed in
+a printed case on a sunny wall can. Read `die_c` from `/api/v1/mesh` for a few
+days before deciding, because throttling transmit power costs range.
+
+**`UPLINK_WATCHDOG_TIMEOUT_S`** is a bet about your AP. 1200 s suits a network
+where a wedge is rare and a reboot is cheap. If your uplink drops briefly and
+often, a short timeout turns a recoverable gap into a reboot loop; if it wedges
+hard, a long one leaves a node dark for twenty minutes.
+
+### A worked example: the same two options, in one house
+
+MEASURED on a nine-node ESP32-C6 fleet in a single detached house. **These are
+our numbers, not yours.** They are here to show the shape of the decision, and
+how much a building can move it.
+
+Four arms as a 2x2 factorial, 20-minute runs, three Latin-square blocks so slow
+drift landed on every arm equally. Metric is the fraction of transmissions held
+in common by two or more nodes.
+
+| arm | mean |
+|---|---|
+| `elapsed` (per-node gate) | 0.2434 |
+| `mesh` (aligned windows) | 0.2480 |
+| `seq` (keep `rx_seq` divisible by 8) | **0.5605** |
+| `mesh` + `seq` | 0.5452 |
+
+`seq` roughly doubled pairing, +31.7 pp, about 70x the measured drift floor and
+reproduced in all three blocks. Mesh alignment bought **+0.5 pp** -- inside
+noise. Stacking them was very slightly *worse* than `seq` alone.
+
+**Why that happened here, and why yours may differ.** These nodes already
+overheard a great deal in common -- two boards side by side heard the same
+transmissions 72% of the time -- so there was a large pool of shared
+transmissions for `seq` to select from, and little left for window alignment to
+recover. A house with fewer shared transmitters, thicker interior walls, or
+nodes spread so that few pairs hear the same radios has less for `seq` to work
+with, and phase alignment may matter more rather than less. We did not measure
+such a house and do not claim to know.
+
+**It is a trade, not a free win.** At period 8 the `seq` arms carried ~75-95k
+transmissions per 20 minutes against ~120-160k ungated: pairing is bought with
+raw frame rate. Absolute paired transmissions per minute still rose (2629 vs
+2524), because the discarded frames are disproportionately ones only one node
+would have kept. Whether that trade is right depends on what consumes your
+stream. On-device edge processing was **unaffected** here -- frames processed
+stayed ~1900 per node per 4 minutes in both modes, because that pipeline is
+separately rate-limited -- so the cost fell on the uplink, not on local sensing.
+If your uplink is the scarce resource, that changes the answer.
+
+**The two options differ in kind, not just in effect.** Mesh alignment is an
+agreement between receivers: it needs a shared clock, so it inherits whatever
+the sync topology does. Selecting by `rx_seq` needs no agreement at all. The
+802.11 sequence control field is assigned by the TRANSMITTER and is identical
+at every receiver, so it is a coordination-free name for one transmission --
+two nodes that have never heard of each other, sit in different sync domains,
+or run with no mesh whatsoever still keep the same subset of frames.
+
+In the code the seq test runs before any sync check and reads only the frame;
+only the mesh branch calls `c6_sync_espnow_is_valid()`. That asymmetry is the
+reason `seq` had nothing to degrade in our runs, and it is worth weighing
+directly: if your fleet's sync is fragile, `seq` is not merely the better
+performer, it is the one with no dependency that can quietly fail.
+
+**A limitation of our own measurement, which cuts against the mesh arm.** The
+mesh gate uses mesh-time buckets only while `c6_sync_espnow_is_valid()`; a node
+with no valid sync falls back to the elapsed gate rather than gating on a
+meaningless epoch. That is the right behaviour, but it means our `mesh` arms
+were partly `elapsed` arms: three of nine nodes never synchronised, so for those
+three the setting under test was silently not in effect. Read the +0.5 pp as
+"mesh where sync held, elapsed where it did not" rather than as a clean
+fleet-wide measurement of alignment.
+
+This is itself a house-dependent property. Time sync here is leader-elected and
+hub-and-spoke -- one node broadcasts and the rest follow. Whether every node can
+hear that leader is a question about your building, not about the firmware. In a
+larger or more divided house the leader may not reach everyone, the fleet
+fragments into sync domains, and any option that depends on shared time degrades
+quietly for the nodes that fell out. Check `is_leader` and sync validity in
+`/api/v1/mesh` before concluding that an alignment setting did or did not help.
+
+**A prediction we got wrong, kept because it is the useful part.** Our mesh had
+split into two leader domains with three nodes never synchronising at all. We
+expected `seq` to win most on pairs spanning that split. Per-pair yield said
+otherwise: same-domain 5.82x, cross-domain 6.24x, involving a never-synced node
+**5.16x** -- the lowest, the opposite of the prediction -- and within-group
+spread (3.6x-8.1x) dwarfed every between-group difference.
+
+So `seq` is **not** a workaround for broken time sync; it wins roughly
+uniformly, including where sync is healthy. The consequence is negative and
+worth having: repairing the mesh split would probably not have closed the gap,
+and that effort would have been spent for nothing.
+
+### Measuring rather than guessing
+
+A gate comparison needs a fixed environment, repeated blocks, and every arm run
+on every node -- otherwise node placement is confounded with the setting. The
+harness used for the published comparison is in the repository; use it rather
+than eyeballing a frame rate, which moves for reasons unrelated to the setting.
@@ -1,6 +1,7 @@
 set(SRCS
-    "main.c" "csi_collector.c"
+    "main.c" "csi_collector.c" "node_log.c"
    "thermal.c" "stream_sender.c" "nvs_config.c"
+    "serial_onboarding.c" "serial_onboarding_protocol.c"
    "edge_processing.c" "ota_update.c" "power_mgmt.c"
    "wasm_runtime.c" "wasm_upload.c" "rvf_parser.c"
    "mmwave_sensor.c"
@@ -14,6 +15,7 @@ set(SRCS
    "c6_twt.c"
    "c6_timesync.c"
    "c6_lp_core.c"
+    "c6_antenna_select.c"
    # ADR-110 D1 workaround — ESP-NOW cross-node sync (works on S3+C6)
    "c6_sync_espnow.c"
    # ADR-110 B1/B2 unblock — soft-AP HE/TWT (C6-only when enabled)
@@ -31,6 +33,9 @@ set(REQUIRES
    esp_http_client
    esp_app_format
    esp_timer
+    fatfs                 # node_log.c: the storage FAT volume
+    wear_levelling        # node_log.c: wl_mount behind that volume
+    espcoredump           # coredump-to-flash readback
    esp_pm
    esp_driver_uart
    esp_driver_gpio
@@ -39,6 +44,8 @@ set(REQUIRES
    driver
    lwip
    mbedtls
+    efuse
+    led_strip
 )

 # ADR-110: C6-only components — pulled in when building for esp32c6.
@@ -48,6 +55,12 @@ if(IDF_TARGET STREQUAL "esp32c6")
    list(APPEND REQUIRES ieee802154 ulp esp_hw_support)
 endif()

+# ESP-IDF 6 split the temperature sensor driver out of the legacy `driver`
+# component. Keep the 5.4 lane working while declaring the v6 dependency.
+if(IDF_VERSION_MAJOR GREATER_EQUAL 6)
+    list(APPEND REQUIRES esp_driver_tsens)
+endif()
+
 # ADR-061: Mock CSI generator for QEMU testing + ADR-081 mock radio binding
 if(CONFIG_CSI_MOCK_ENABLED)
    list(APPEND SRCS "mock_csi.c" "rv_radio_ops_mock.c")
@@ -1,5 +1,27 @@
 menu "CSI Node Configuration"

+    config C6_XIAO_ANTENNA_SELECT
+        bool "Control the Seeed XIAO ESP32-C6 RF switch"
+        depends on IDF_TARGET_ESP32C6
+        default n
+        help
+            Enable only for Seeed XIAO ESP32-C6 boards. The XIAO uses GPIO3
+            to enable RF-switch control and GPIO14 to choose its internal or
+            external antenna. Leave this disabled for generic ESP32-C6 boards
+            because GPIO3 and GPIO14 may have unrelated functions there.
+
+    choice C6_XIAO_ANTENNA_PATH
+        prompt "Seeed XIAO ESP32-C6 antenna path"
+        depends on C6_XIAO_ANTENNA_SELECT
+        default C6_XIAO_ANTENNA_INTERNAL
+
+        config C6_XIAO_ANTENNA_INTERNAL
+            bool "Internal ceramic antenna"
+
+        config C6_XIAO_ANTENNA_EXTERNAL
+            bool "External U.FL antenna"
+    endchoice
+
    config CSI_NODE_ID
        int "Node ID (0-255)"
        default 1
@@ -651,3 +673,20 @@ config UPLINK_WATCHDOG_TIMEOUT_S
      packet's health field before assuming the watchdog is responsible.

 endmenu
+
+config CSI_GATE_MESH_ALIGNED
+    bool "Align the CSI rate gate to mesh time (enables cross-node pairing)"
+    default y
+    help
+      The per-node elapsed gate ("20 ms since MY last accept") gives every node
+      an independent phase, so two healthy nodes at 50 Hz accept disjoint
+      frames and nothing can be paired across them. This aligns the 20 ms
+      window to mesh time so nodes choose the same windows.
+
+config CSI_SEQ_DIAG
+    bool "Log (source MAC, rx_seq) for every CSI callback (ADR-345 phase 2 probe)"
+    default n
+    help
+      Diagnostic. Emits the transmitter address and 802.11 sequence number for
+      each CSI callback so the effect of the gate above can be measured rather
+      than assumed. Verbose; leave off in normal operation.
@@ -0,0 +1,56 @@
+#include "c6_antenna_select.h"
+
+#include "sdkconfig.h"
+
+#if defined(CONFIG_IDF_TARGET_ESP32C6) && defined(CONFIG_C6_XIAO_ANTENNA_SELECT)
+#include "driver/gpio.h"
+#include "esp_log.h"
+#include "freertos/FreeRTOS.h"
+#include "freertos/task.h"
+
+#define XIAO_RF_SWITCH_POWER_GPIO GPIO_NUM_3
+#define XIAO_RF_SWITCH_SELECT_GPIO GPIO_NUM_14
+
+static const char *TAG = "c6_antenna";
+#endif
+
+esp_err_t c6_xiao_antenna_apply(void)
+{
+#if defined(CONFIG_IDF_TARGET_ESP32C6) && defined(CONFIG_C6_XIAO_ANTENNA_SELECT)
+    gpio_config_t config = {
+        .pin_bit_mask = (1ULL << XIAO_RF_SWITCH_POWER_GPIO) |
+                        (1ULL << XIAO_RF_SWITCH_SELECT_GPIO),
+        .mode = GPIO_MODE_OUTPUT,
+        .pull_up_en = GPIO_PULLUP_DISABLE,
+        .pull_down_en = GPIO_PULLDOWN_DISABLE,
+        .intr_type = GPIO_INTR_DISABLE,
+    };
+    esp_err_t err = gpio_config(&config);
+    if (err != ESP_OK) {
+        return err;
+    }
+
+    err = gpio_set_level(XIAO_RF_SWITCH_POWER_GPIO, 0);
+    if (err != ESP_OK) {
+        return err;
+    }
+    vTaskDelay(pdMS_TO_TICKS(100));
+
+#if defined(CONFIG_C6_XIAO_ANTENNA_EXTERNAL)
+    const c6_xiao_antenna_t antenna = C6_XIAO_ANTENNA_EXTERNAL;
+    const char *name = "external U.FL";
+#else
+    const c6_xiao_antenna_t antenna = C6_XIAO_ANTENNA_INTERNAL;
+    const char *name = "internal ceramic";
+#endif
+
+    err = gpio_set_level(XIAO_RF_SWITCH_SELECT_GPIO,
+                         c6_xiao_antenna_gpio14_level(antenna));
+    if (err == ESP_OK) {
+        ESP_LOGI(TAG, "XIAO ESP32-C6 antenna path: %s", name);
+    }
+    return err;
+#else
+    return ESP_OK;
+#endif
+}
@@ -0,0 +1,17 @@
+#pragma once
+
+typedef enum {
+    C6_XIAO_ANTENNA_INTERNAL = 0,
+    C6_XIAO_ANTENNA_EXTERNAL = 1,
+} c6_xiao_antenna_t;
+
+static inline int c6_xiao_antenna_gpio14_level(c6_xiao_antenna_t antenna)
+{
+    return antenna == C6_XIAO_ANTENNA_EXTERNAL ? 1 : 0;
+}
+
+#ifdef ESP_PLATFORM
+#include "esp_err.h"
+
+esp_err_t c6_xiao_antenna_apply(void);
+#endif
@@ -13,7 +13,7 @@
 *      `ulp_embed_binary(...)` in main/CMakeLists.txt from lp_core/main.c.
 *
 *   2. DISABLED — falls back to plain deep-sleep + GPIO wake-up
- *      (`esp_deep_sleep_enable_gpio_wakeup`). No debounce, no
+ *      (ESP-IDF deep-sleep GPIO wake API). No debounce, no
 *      sub-10 µA floor, but no LP toolchain dependency either.
 *      This is the path the v0.6.6 firmware shipped with.
 *
@@ -26,6 +26,7 @@
 #if defined(CONFIG_IDF_TARGET_ESP32C6) && defined(CONFIG_ULP_COPROC_TYPE_LP_CORE)

 #include "c6_lp_core.h"
+#include "esp_idf_version.h"
 #include "esp_log.h"
 #include "esp_sleep.h"
 #include "driver/rtc_io.h"
@@ -134,10 +135,17 @@ esp_err_t c6_lp_core_arm(int wake_gpio, bool active_high)
 #else
    /* --- Fallback path: plain deep-sleep GPIO wakeup (~10 µA floor) --- */
    uint64_t mask = 1ULL << wake_gpio;
+#if ESP_IDF_VERSION >= ESP_IDF_VERSION_VAL(6, 0, 0)
+    esp_sleep_gpio_wake_up_mode_t mode = active_high
+        ? ESP_GPIO_WAKEUP_GPIO_HIGH
+        : ESP_GPIO_WAKEUP_GPIO_LOW;
+    esp_err_t err = esp_sleep_enable_gpio_wakeup_on_hp_periph_powerdown(mask, mode);
+#else
    esp_deepsleep_gpio_wake_up_mode_t mode = active_high
        ? ESP_GPIO_WAKEUP_GPIO_HIGH
        : ESP_GPIO_WAKEUP_GPIO_LOW;
    esp_err_t err = esp_deep_sleep_enable_gpio_wakeup(mask, mode);
+#endif
    if (err != ESP_OK) {
        ESP_LOGE(TAG, "enable_gpio_wakeup failed: %s", esp_err_to_name(err));
        return err;
@@ -114,6 +114,9 @@ static int64_t s_last_send_us = 0;
 */
 #define CSI_MIN_PROCESS_INTERVAL_US  (20 * 1000)  /* 50 Hz */
 static int64_t s_last_process_us = 0;
+/* Mesh-epoch window index of the last accepted frame. UINT64_MAX means "none
+ * yet", which no real bucket can collide with. */
+static uint64_t s_last_gate_bucket = UINT64_MAX;
 static uint32_t s_early_drop = 0;

 /* ---- ADR-029: Channel-hop state ---- */
@@ -263,8 +266,16 @@ size_t csi_serialize_frame(const wifi_csi_info_t *info, uint8_t *buf, size_t buf
    buf[19] = 0;
 #endif

-    /* I/Q data */
+    /* I/Q data. ESP-IDF documents that the first four CSI bytes are invalid
+     * when first_word_invalid is set. Never let those hardware artifacts feed
+     * either the host or edge DSP path. Preserve the fixed ADR-018 geometry by
+     * zeroing rather than removing bytes, and mark the sanitation in bit 5. */
    memcpy(&buf[CSI_HEADER_SIZE], info->buf, iq_len);
+    if (info->first_word_invalid && iq_len > 0) {
+        size_t invalid_len = iq_len < 4 ? iq_len : 4;
+        memset(&buf[CSI_HEADER_SIZE], 0, invalid_len);
+        buf[19] |= CSI_FLAG_FIRST_WORD_SANITIZED;
+    }

    return frame_size;
 }
@@ -277,9 +288,53 @@ static void wifi_csi_callback(void *ctx, wifi_csi_info_t *info)
    (void)ctx;

    /* Early rate gate: drop excess callbacks to ~50 Hz to prevent
-     * SPI flash cache crash in WiFi ISR (wDev_ProcessFiq). */
+     * SPI flash cache crash in WiFi ISR (wDev_ProcessFiq).
+     *
+     * HOW the rate is limited decides whether cross-node fusion is possible.
+     *
+     * The original gate is "at least 20 ms since MY last accept". Each node
+     * therefore has an independent phase: node A can accept at t=0,20,40 ms
+     * while node B accepts at 7,27,47. Both are perfectly healthy and both hit
+     * 50 Hz, yet they accept disjoint frames and nothing can be paired.
+     *
+     * MEASURED 2026-08-30, two boards side by side: they HEARD the same
+     * transmissions 72% of the time but only 25% of accepted frames were
+     * common. The frames were there; the gate was throwing away the pairing.
+     *
+     * So gate on a bucket of the MESH-ALIGNED epoch instead: every node takes
+     * the first frame it hears in the same absolute 20 ms window. Two nodes
+     * that heard the same frame now both accept it. Mesh sync is good to
+     * roughly 490 us against a 20 ms bucket -- about 2.5% of a window -- so
+     * boundary disagreements are rare.
+     *
+     * Falls back to the original elapsed-time gate whenever mesh sync is not
+     * valid (no leader heard yet, or a node that just booted), because an
+     * unsynced epoch would otherwise gate on a meaningless number. A node
+     * running unsynced simply gets the old behaviour rather than no gate.
+     *
+     * The half-interval floor below keeps the crash protection honest: bucket
+     * gating alone could accept at the end of one window and the start of the
+     * next, back to back. The floor bounds that to ~100 Hz for a single pair
+     * while the average stays at 50 Hz. Do not remove it; the gate exists for
+     * a crash, not for tidiness. */
    int64_t now_us = esp_timer_get_time();
-    if ((now_us - s_last_process_us) < CSI_MIN_PROCESS_INTERVAL_US) {
+    bool take;
+#ifdef CONFIG_CSI_GATE_MESH_ALIGNED
+    if (c6_sync_espnow_is_valid()) {
+        uint64_t bucket = c6_sync_espnow_get_epoch_us()
+                        / (uint64_t)CSI_MIN_PROCESS_INTERVAL_US;
+        take = (bucket != s_last_gate_bucket)
+            && ((now_us - s_last_process_us) >= CSI_MIN_PROCESS_INTERVAL_US / 2);
+        if (take) {
+            s_last_gate_bucket = bucket;
+        }
+    } else {
+        take = (now_us - s_last_process_us) >= CSI_MIN_PROCESS_INTERVAL_US;
+    }
+#else
+    take = (now_us - s_last_process_us) >= CSI_MIN_PROCESS_INTERVAL_US;
+#endif
+    if (!take) {
        s_early_drop++;
        return;
    }
@@ -330,13 +385,16 @@ static void wifi_csi_callback(void *ctx, wifi_csi_info_t *info)
     * while the on-device Tier 1/2 pipeline receives a uniform, sustainable
     * stream. Enqueuing every burst frame overloaded the unicore C6 DSP and
     * turned 30-40 callback pps into an irregular approximately 8 Hz subset. */
-    if (info->buf && info->len > 0) {
+    if (frame_len > CSI_HEADER_SIZE) {
        if (s_next_edge_enqueue_us == 0) {
            s_next_edge_enqueue_us = now_us;
        }

        if (now_us >= s_next_edge_enqueue_us) {
-            (void)edge_enqueue_csi((const uint8_t *)info->buf, (uint16_t)info->len,
+            /* Reuse the sanitized ADR-018 payload. Feeding info->buf here
+             * would reintroduce first_word_invalid artifacts on device. */
+            (void)edge_enqueue_csi(&frame_buf[CSI_HEADER_SIZE],
+                                   (uint16_t)(frame_len - CSI_HEADER_SIZE),
                                   (int8_t)info->rx_ctrl.rssi, info->rx_ctrl.channel);

            /* Preserve the configured sample clock instead of resetting it to
@@ -692,6 +750,20 @@ uint16_t csi_collector_get_send_fail_count(void)
    return (f > 0xFFFFu) ? 0xFFFFu : (uint16_t)f;
 }

+/* The gate here is fixed at compile time (mesh-aligned bucketing, falling
+ * back to elapsed time when unsynced), so there is no mode or period to
+ * report. Return the explicit sentinel rather than a number that reads as
+ * a real setting. */
+uint8_t csi_collector_get_gate_mode(void)
+{
+    return CSI_GATE_NOT_CONFIGURABLE;
+}
+
+uint8_t csi_collector_get_gate_seq_period(void)
+{
+    return CSI_GATE_NOT_CONFIGURABLE;
+}
+
 /* ---- ADR-029: Channel hopping ---- */

 void csi_collector_set_hop_table(const uint8_t *channels, uint8_t hop_count, uint32_t dwell_ms)
@@ -17,6 +17,9 @@
 /** ADR-018 header size in bytes. */
 #define CSI_HEADER_SIZE 20

+/** ADR-018 byte 19: ESP-IDF reported and firmware sanitized invalid CSI prefix. */
+#define CSI_FLAG_FIRST_WORD_SANITIZED (1U << 5)
+
 /** Maximum frame buffer size (header + 4 antennas * 256 subcarriers * 2 bytes). */
 #define CSI_MAX_FRAME_SIZE (CSI_HEADER_SIZE + 4 * 256 * 2)

@@ -136,4 +139,22 @@ uint16_t csi_collector_get_pkt_yield_per_sec(void);
 */
 uint16_t csi_collector_get_send_fail_count(void);

+/** Reported by the gate accessors when this build has no selectable gate. */
+#define CSI_GATE_NOT_CONFIGURABLE 0xFF
+
+/**
+ * Report which frame-selection gate is in force, for the on-node log.
+ *
+ * This build has exactly one gate -- mesh-aligned bucketing with an
+ * elapsed-time fallback -- fixed at compile time, so there is no mode or
+ * period to report and both accessors return CSI_GATE_NOT_CONFIGURABLE.
+ *
+ * They exist so the log record keeps a field of fixed width and meaning
+ * whether or not a build can select a gate at runtime, and so an explicit
+ * "not applicable" is stored rather than a plausible number that would
+ * later be reasoned from.
+ */
+uint8_t csi_collector_get_gate_mode(void);
+uint8_t csi_collector_get_gate_seq_period(void);
+
 #endif /* CSI_COLLECTOR_H */
@@ -21,9 +21,11 @@
 #include "led_strip.h"

 #include "csi_collector.h"
+#include "node_log.h"
 #include "thermal.h"
 #include "stream_sender.h"
 #include "nvs_config.h"
+#include "serial_onboarding.h"
 #include "edge_processing.h"
 #include "ota_update.h"
 #include "power_mgmt.h"
@@ -37,6 +39,7 @@
 #include "c6_twt.h"                /* ADR-110: TWT (no-op stub on S3) */
 #include "c6_timesync.h"           /* ADR-110: 802.15.4 mesh time-sync (no-op on S3) */
 #include "c6_lp_core.h"            /* ADR-110: LP-core hibernation (no-op on S3) */
+#include "c6_antenna_select.h"     /* XIAO C6 RF switch (opt-in; generic C6 no-op) */
 #include "c6_sync_espnow.h"        /* ADR-110 D1 workaround: ESP-NOW sync */
 #include "c6_softap_he.h"          /* ADR-110 B1/B2: HE/TWT soft-AP (no-op when disabled) */
 #ifdef CONFIG_CSI_MOCK_ENABLED
@@ -115,6 +118,10 @@ static void event_handler(void *arg, esp_event_base_t event_base,
    } else if (event_base == WIFI_EVENT && event_id == WIFI_EVENT_STA_DISCONNECTED) {
        wifi_event_sta_disconnected_t *disc = (wifi_event_sta_disconnected_t *)event_data;
        ESP_LOGW(TAG, "WiFi disconnected, reason=%d rssi=%d", disc->reason, disc->rssi);
+        /* The 7.5 h outage was root-caused to the MAX_RETRY latch only because
+         * someone was watching the console at the time. Persist it. */
+        node_log_note_disconnect((uint8_t)disc->reason, (int8_t)disc->rssi);
+        node_log_event(NODE_LOG_EV_WIFI_DISCONNECT, disc->reason, disc->rssi);
        s_retry_num++;
        /* Release the boot wait once, so a node that comes up while the AP is
         * down still starts CSI capture and the mesh instead of blocking in
@@ -331,6 +338,19 @@ void app_main(void)
    ESP_LOGI(TAG, "%s CSI Node (ADR-018 / ADR-110) — v%s — Node ID: %d",
             target_name, app_desc->version, g_nvs_config.node_id);

+    /* Apply the opt-in XIAO RF path before WiFi starts. Generic C6 boards keep
+     * ownership of GPIO3 and GPIO14 because the default implementation is a
+     * no-op unless CONFIG_C6_XIAO_ANTENNA_SELECT is enabled. */
+    ESP_ERROR_CHECK(c6_xiao_antenna_apply());
+    /* The native Mac onboarding bridge must remain available even when WiFi
+     * credentials or the aggregator address are wrong. Start it before any
+     * blocking network initialization. The protocol is physical-USB-only,
+     * nonce-bound, bounded, and never prints credentials. */
+    esp_err_t onboarding_ret = serial_onboarding_start(&g_nvs_config);
+    if (onboarding_ret != ESP_OK) {
+        ESP_LOGW(TAG, "USB onboarding unavailable: %s", esp_err_to_name(onboarding_ret));
+    }
+
    /* Onboard WS2812. C6 wires the LED to GPIO 8; S3 to GPIO 38 (DevKitC-1 v1.0)
     * or GPIO 48 (DevKitC-1 v1.1 / N16R8 — see #962). On S3 we drive 48 (the
     * common module). On C6, GPIO 38/48 don't exist (only 0-30) — gate by target.
@@ -445,6 +465,24 @@ void app_main(void)
        } else {
            ESP_LOGI(TAG, "reset reason: %s (%d)", why, (int)rr);
        }
+
+        /* And persist it. The console line above is exactly what a power cycle
+         * destroys, which is the whole reason this fleet has no post-mortem for
+         * a remote fault. node_log_init failing is non-fatal by design -- the
+         * node comes up either way, it just has no memory. */
+        if (node_log_init() == ESP_OK) {
+            uint32_t prev_uptime_s = 0;
+            nvs_handle_t nh;
+            if (nvs_open("nodelog", NVS_READWRITE, &nh) == ESP_OK) {
+                nvs_get_u32(nh, "last_up_s", &prev_uptime_s);
+                nvs_set_u32(nh, "last_up_s", 0);
+                nvs_commit(nh);
+                nvs_close(nh);
+            }
+            node_log_boot((uint32_t)rr, prev_uptime_s);
+            ESP_LOGI(TAG, "on-node log active: boot_id=%u, %u records retained",
+                     (unsigned)node_log_boot_id(), (unsigned)node_log_count());
+        }
    }

    /* Bring thermal monitoring up before the radio is loaded, so the first
@@ -649,5 +687,24 @@ void app_main(void)
 #ifdef CONFIG_UPLINK_WATCHDOG
        uplink_watchdog_tick();
 #endif
+        /* Offered every 10 s; node_log enforces its own floor, so the cadence
+         * lives in one place rather than being implied by this loop's delay.
+         * Also refresh the uptime NVS cell, which is what lets the NEXT boot
+         * record say how long the previous session actually survived -- the
+         * difference between "it rebooted" and "it wedged after 225 s". */
+        node_log_periodic();
+        {
+            static uint32_t s_last_persist_s;
+            uint32_t up_s = (uint32_t)(esp_timer_get_time() / 1000000);
+            if (up_s - s_last_persist_s >= 60) {
+                s_last_persist_s = up_s;
+                nvs_handle_t nh;
+                if (nvs_open("nodelog", NVS_READWRITE, &nh) == ESP_OK) {
+                    nvs_set_u32(nh, "last_up_s", up_s);
+                    nvs_commit(nh);
+                    nvs_close(nh);
+                }
+            }
+        }
    }
 }
@@ -503,9 +503,35 @@ esp_err_t mmwave_sensor_init(int uart_tx_pin, int uart_rx_pin)

    return ESP_OK;

+#else
+    /* Default probe pins must never collide with the UART0 console. On the
+     * ESP32-C6 the console is TX=GPIO16 / RX=GPIO17, so the legacy 17/18 pair
+     * routed UART1 TX onto the console RX line and silently killed serial
+     * input (USB onboarding, monitor commands) even when no sensor was found,
+     * because uart_driver_delete() does not undo the GPIO matrix routing. */
+#if defined(CONFIG_IDF_TARGET_ESP32C6)
+    if (uart_tx_pin < 0) uart_tx_pin = 4;
+    if (uart_rx_pin < 0) uart_rx_pin = 5;
 #else
    if (uart_tx_pin < 0) uart_tx_pin = 17;
    if (uart_rx_pin < 0) uart_rx_pin = 18;
+#endif
+#if defined(CONFIG_ESP_CONSOLE_UART_CUSTOM)
+    const int console_tx = CONFIG_ESP_CONSOLE_UART_TX_GPIO;
+    const int console_rx = CONFIG_ESP_CONSOLE_UART_RX_GPIO;
+#elif defined(CONFIG_IDF_TARGET_ESP32C6)
+    const int console_tx = 16, console_rx = 17;   /* U0TXD / U0RXD IOMUX pins */
+#elif defined(CONFIG_IDF_TARGET_ESP32S3)
+    const int console_tx = 43, console_rx = 44;
+#else
+    const int console_tx = 1, console_rx = 3;
+#endif
+    if (uart_tx_pin == console_tx || uart_tx_pin == console_rx ||
+        uart_rx_pin == console_tx || uart_rx_pin == console_rx) {
+        ESP_LOGW(TAG, "mmWave probe pins (TX=%d, RX=%d) overlap the console UART (TX=%d, RX=%d); skipping probe",
+                 uart_tx_pin, uart_rx_pin, console_tx, console_rx);
+        return ESP_ERR_INVALID_ARG;
+    }

    /* Install UART driver at MR60 baud (will be changed during probe). */
    uart_config_t uart_config = {
@@ -0,0 +1,424 @@
+#include "node_log.h"
+
+#include <limits.h>
+#include <string.h>
+#include <unistd.h>
+
+#include "esp_log.h"
+#include "esp_system.h"
+#include "esp_timer.h"
+#include "esp_vfs_fat.h"
+#include "esp_wifi.h"
+#include "freertos/FreeRTOS.h"
+#include "freertos/semphr.h"
+#include "nvs.h"
+#include "nvs_flash.h"
+
+#include "c6_sync_espnow.h"
+#include "csi_collector.h"
+#include "nvs_config.h"
+#include "thermal.h"
+
+/* firmware/esp32-csi-node/partitions_4mb.csv has two 1.81 MB app slots and
+ * only 256 KB free -- no room for the FAT volume this module needs. The
+ * whole implementation below is compiled out on that profile; every entry
+ * point still links via the stubs in the #else branch so main.c's call
+ * sites need no #ifdef of their own. See partitions_display.csv (8MB) and
+ * partitions_16mb.csv for the profiles where this module is active. */
+#ifndef CONFIG_ESPTOOLPY_FLASHSIZE_4MB
+
+static const char *TAG = "node_log";
+
+/* The FAT volume reserved in partitions_16mb.csv (storage, 8000K) and never
+ * mounted until now. */
+#define NODE_LOG_PARTITION  "storage"
+#define NODE_LOG_MOUNT      "/nlog"
+#define NODE_LOG_PATH       NODE_LOG_MOUNT "/health.bin"
+
+/* Ring capacity. 60000 * 128 B = 7.68 MB, just inside the 8000K volume with
+ * room for FAT's own metadata. At the 300 s cadence that is ~208 days. */
+#define NODE_LOG_MAX_RECORDS 60000
+
+/* Hard floor between periodic samples. The design settled on 300 s; this is
+ * the enforcement, not the schedule. A caller asking more often is DROPPED
+ * rather than served, because flash wear is the one way this module can do
+ * harm and a bug in a caller must not be able to cause it. */
+#define NODE_LOG_MIN_PERIOD_S 60
+
+/* Events bypass the periodic floor -- they are rare and they are the whole
+ * point -- but not without limit, or a disconnect storm becomes a write storm. */
+#define NODE_LOG_MIN_EVENT_MS 1000
+
+static bool              s_active;
+static FILE             *s_fp;
+static wl_handle_t       s_wl = WL_INVALID_HANDLE;
+static SemaphoreHandle_t s_lock;
+static uint16_t          s_boot_id;
+static uint32_t          s_seq;
+static size_t            s_count;      /* records currently in the ring */
+static size_t            s_head;       /* next slot to write */
+static int64_t           s_last_periodic_us;
+static int64_t           s_last_event_us;
+
+/* CRC16/CCITT-FALSE. A record that fails this is skipped by the reader rather
+ * than trusted, which matters because a power cut mid-write leaves a partial
+ * record and the ring has no other way to know. */
+static uint16_t crc16(const uint8_t *p, size_t n)
+{
+    uint16_t crc = 0xFFFF;
+    for (size_t i = 0; i < n; i++) {
+        crc ^= (uint16_t)p[i] << 8;
+        for (int b = 0; b < 8; b++) {
+            crc = (crc & 0x8000) ? (uint16_t)((crc << 1) ^ 0x1021) : (uint16_t)(crc << 1);
+        }
+    }
+    return crc;
+}
+
+/* 16 B header, then a type-specific payload. The header is identical across
+ * types so a reader can order and validate without dispatching first. */
+typedef struct __attribute__((packed)) {
+    uint8_t  type;
+    uint8_t  flags;
+    uint16_t boot_id;
+    uint32_t seq;
+    uint32_t uptime_s;
+    uint16_t payload_len;
+    uint16_t crc16;        /* over the record with this field zeroed */
+} node_log_hdr_t;
+
+_Static_assert(sizeof(node_log_hdr_t) == 16, "header must be 16 B");
+
+/* ~72 B used of the 112 B payload budget, leaving ~40 B of deliberate slack so
+ * a field can be added later WITHOUT changing the record size and invalidating
+ * every reader already in the field. */
+typedef struct __attribute__((packed)) {
+    int8_t   die_c;
+    uint8_t  thermal_state;
+    int8_t   tx_dbm;
+    int8_t   ap_rssi_dbm;      /* the one field we did not have and needed */
+    uint8_t  channel;
+    uint8_t  wifi_state;
+    uint8_t  gate_mode;
+    uint8_t  gate_seq_period;
+    uint16_t free_heap_kib;
+    uint16_t min_heap_kib;
+    uint16_t csi_fps_x100;
+    uint32_t frames_processed;
+    uint32_t frames_rejected;
+    uint32_t seq_drop;
+    uint32_t tx_early_drop;
+    uint16_t tx_rate_skip;
+    uint32_t tx_send_fail;
+    uint16_t disconnect_count;
+    uint8_t  last_disc_reason;
+    int8_t   last_disc_rssi;
+    uint8_t  mesh_flags;       /* bit0 valid, bit1 leader */
+    uint8_t  leader_id;
+    int32_t  mesh_offset_us;
+    uint16_t mesh_staleness_ms;
+    uint32_t mesh_seq;
+} node_log_periodic_t;
+
+typedef struct __attribute__((packed)) {
+    uint32_t reset_reason;
+    uint32_t prev_uptime_s;
+    node_log_periodic_t health;   /* a boot record carries a snapshot too */
+} node_log_boot_t;
+
+typedef struct __attribute__((packed)) {
+    uint8_t  subtype;
+    uint8_t  _pad[3];
+    int32_t  a;
+    int32_t  b;
+} node_log_event_t;
+
+/* Counters main.c owns; set through the setters below rather than reached for,
+ * so this module has no include cycle with main.c. */
+static volatile uint16_t s_disconnect_count;
+static volatile uint8_t  s_last_disc_reason;
+static volatile int8_t   s_last_disc_rssi;
+
+void node_log_note_disconnect(uint8_t reason, int8_t rssi)
+{
+    s_disconnect_count++;
+    s_last_disc_reason = reason;
+    s_last_disc_rssi = rssi;
+}
+
+static void fill_health(node_log_periodic_t *h)
+{
+    memset(h, 0, sizeof(*h));
+
+    /* thermal.c initialises s_last_c to -273.0f and only replaces it on the
+     * first thermal_tick(), which runs from the adaptive controller -- LATER
+     * than the boot record and later than the first periodic samples. Casting
+     * that sentinel to int8 yields -17, a PLAUSIBLE temperature, which is
+     * exactly the kind of invented-but-believable number that must never reach
+     * a log someone will later reason from. Store INT8_MIN as an explicit
+     * "no reading" instead; node_log_read.py renders it as n/a. */
+    float die = thermal_celsius();
+    h->die_c = (die < -100.0f || die > 125.0f) ? INT8_MIN : (int8_t)die;
+    h->thermal_state   = (uint8_t)thermal_state();
+    h->tx_dbm          = thermal_tx_dbm();
+    h->gate_mode       = csi_collector_get_gate_mode();
+    h->gate_seq_period = csi_collector_get_gate_seq_period();
+
+    /* The association link, NOT the CSI-derived rssi_median_dbm in
+     * adaptive_controller.c. Nodes 5 and 6 show every symptom of a bad uplink
+     * and this is the one call that can confirm or refute it. */
+    wifi_ap_record_t ap;
+    if (esp_wifi_sta_get_ap_info(&ap) == ESP_OK) {
+        h->ap_rssi_dbm = (int8_t)ap.rssi;
+        h->channel     = ap.primary;
+        h->wifi_state  = 1;
+    }
+
+    h->free_heap_kib = (uint16_t)(esp_get_free_heap_size() / 1024);
+    h->min_heap_kib  = (uint16_t)(esp_get_minimum_free_heap_size() / 1024);
+    h->csi_fps_x100  = csi_collector_get_pkt_yield_per_sec() * 100;
+    h->tx_send_fail  = csi_collector_get_send_fail_count();
+
+    h->disconnect_count  = s_disconnect_count;
+    h->last_disc_reason  = s_last_disc_reason;
+    h->last_disc_rssi    = s_last_disc_rssi;
+
+    h->mesh_flags = (uint8_t)((c6_sync_espnow_is_valid() ? 1 : 0)
+                            | (c6_sync_espnow_is_leader() ? 2 : 0));
+    int64_t off = c6_sync_espnow_get_offset_us();
+    /* Saturate rather than wrap: a wrapped offset reads as a plausible small
+     * number and would be believed. */
+    if (off > INT32_MAX)      h->mesh_offset_us = INT32_MAX;
+    else if (off < INT32_MIN) h->mesh_offset_us = INT32_MIN;
+    else                      h->mesh_offset_us = (int32_t)off;
+}
+
+/* Append one record. Callers hold no lock; this takes it. */
+static void append(uint8_t type, const void *payload, size_t len)
+{
+    if (!s_active || len > (NODE_LOG_RECORD_SIZE - sizeof(node_log_hdr_t))) {
+        return;
+    }
+    if (xSemaphoreTake(s_lock, pdMS_TO_TICKS(200)) != pdTRUE) {
+        return;   /* never block a caller on the log */
+    }
+
+    uint8_t rec[NODE_LOG_RECORD_SIZE];
+    memset(rec, 0, sizeof(rec));
+    node_log_hdr_t *h = (node_log_hdr_t *)rec;
+    h->type        = type;
+    h->boot_id     = s_boot_id;
+    h->seq         = ++s_seq;
+    h->uptime_s    = (uint32_t)(esp_timer_get_time() / 1000000);
+    h->payload_len = (uint16_t)len;
+    h->crc16       = 0;
+    memcpy(rec + sizeof(*h), payload, len);
+    h->crc16 = crc16(rec, sizeof(rec));
+
+    if (fseek(s_fp, (long)(s_head * NODE_LOG_RECORD_SIZE), SEEK_SET) == 0
+        && fwrite(rec, 1, sizeof(rec), s_fp) == sizeof(rec)) {
+        /* fflush only pushes the C stdio buffer into the VFS; FATFS still holds
+         * the directory entry and FAT chain in RAM. Without fsync a reboot
+         * loses the file's size, and on the next open "r+b" sees a zero-length
+         * file -- which is precisely what the node-3 pilot showed: boot 1's
+         * records vanished while the NVS-backed prev_uptime survived. A log
+         * that does not survive a power cycle is the exact thing this module
+         * exists to prevent, so the cost of an fsync per record is accepted:
+         * at one record per 60 s it is nothing, and the bounded write rate is
+         * what keeps it that way. */
+        fflush(s_fp);
+        fsync(fileno(s_fp));
+        s_head = (s_head + 1) % NODE_LOG_MAX_RECORDS;
+        if (s_count < NODE_LOG_MAX_RECORDS) s_count++;
+    } else {
+        ESP_LOGW(TAG, "record write failed; disabling to protect the volume");
+        s_active = false;
+    }
+    xSemaphoreGive(s_lock);
+}
+
+esp_err_t node_log_init(void)
+{
+    if (s_active) return ESP_OK;
+
+    s_lock = xSemaphoreCreateMutex();
+    if (!s_lock) return ESP_ERR_NO_MEM;
+
+    const esp_vfs_fat_mount_config_t cfg = {
+        .format_if_mount_failed = true,
+        .max_files              = 2,
+        .allocation_unit_size   = CONFIG_WL_SECTOR_SIZE,
+    };
+    esp_err_t err = esp_vfs_fat_spiflash_mount_rw_wl(
+        NODE_LOG_MOUNT, NODE_LOG_PARTITION, &cfg, &s_wl);
+    if (err != ESP_OK) {
+        ESP_LOGW(TAG, "FAT mount failed (%s); logging DISABLED, node unaffected",
+                 esp_err_to_name(err));
+        return err;
+    }
+
+    /* boot_id orders records across reboots. Without an RTC it is the only
+     * ordering that survives a power cycle. */
+    nvs_handle_t nh;
+    if (nvs_open("nodelog", NVS_READWRITE, &nh) == ESP_OK) {
+        uint16_t b = 0;
+        nvs_get_u16(nh, "boot_id", &b);
+        s_boot_id = (uint16_t)(b + 1);
+        nvs_set_u16(nh, "boot_id", s_boot_id);
+        nvs_commit(nh);
+        nvs_close(nh);
+    }
+
+    s_fp = fopen(NODE_LOG_PATH, "r+b");
+    if (!s_fp) {
+        /* First boot only. Create it, then fsync so the directory entry is on
+         * flash before anything is written into it. */
+        s_fp = fopen(NODE_LOG_PATH, "w+b");
+        if (s_fp) {
+            fflush(s_fp);
+            fsync(fileno(s_fp));
+        }
+    }
+    if (!s_fp) {
+        ESP_LOGW(TAG, "cannot open %s; logging DISABLED", NODE_LOG_PATH);
+        esp_vfs_fat_spiflash_unmount_rw_wl(NODE_LOG_MOUNT, s_wl);
+        s_wl = WL_INVALID_HANDLE;
+        return ESP_FAIL;
+    }
+
+    /* Recover head/seq by scanning. The ring has no superblock deliberately:
+     * a superblock is one more thing a power cut can leave inconsistent, and
+     * the scan is a one-off cost at boot. */
+    uint8_t rec[NODE_LOG_RECORD_SIZE];
+    uint32_t best_seq = 0;
+    for (size_t i = 0; i < NODE_LOG_MAX_RECORDS; i++) {
+        if (fseek(s_fp, (long)(i * NODE_LOG_RECORD_SIZE), SEEK_SET) != 0) break;
+        if (fread(rec, 1, sizeof(rec), s_fp) != sizeof(rec)) break;
+        node_log_hdr_t *h = (node_log_hdr_t *)rec;
+        if (h->type == 0) continue;
+        uint16_t got = h->crc16;
+        h->crc16 = 0;
+        if (crc16(rec, sizeof(rec)) != got) continue;
+        s_count++;
+        if (h->seq > best_seq) {
+            best_seq = h->seq;
+            s_head = (i + 1) % NODE_LOG_MAX_RECORDS;
+        }
+    }
+    s_seq = best_seq;
+    s_active = true;
+    ESP_LOGI(TAG, "logging active: boot_id=%u recovered=%u records, head=%u",
+             (unsigned)s_boot_id, (unsigned)s_count, (unsigned)s_head);
+    return ESP_OK;
+}
+
+bool node_log_is_active(void) { return s_active; }
+uint16_t node_log_boot_id(void) { return s_boot_id; }
+size_t node_log_count(void) { return s_count; }
+
+void node_log_boot(uint32_t reset_reason, uint32_t prev_uptime_s)
+{
+    node_log_boot_t b;
+    memset(&b, 0, sizeof(b));
+    b.reset_reason  = reset_reason;
+    b.prev_uptime_s = prev_uptime_s;
+    fill_health(&b.health);
+    append(NODE_LOG_TYPE_BOOT, &b, sizeof(b));
+}
+
+void node_log_periodic(void)
+{
+    int64_t now = esp_timer_get_time();
+    if (s_last_periodic_us != 0
+        && (now - s_last_periodic_us) < (int64_t)NODE_LOG_MIN_PERIOD_S * 1000000) {
+        return;
+    }
+    s_last_periodic_us = now;
+    node_log_periodic_t h;
+    fill_health(&h);
+    append(NODE_LOG_TYPE_PERIODIC, &h, sizeof(h));
+}
+
+void node_log_event(uint8_t subtype, int32_t a, int32_t b)
+{
+    int64_t now = esp_timer_get_time();
+    if (s_last_event_us != 0
+        && (now - s_last_event_us) < (int64_t)NODE_LOG_MIN_EVENT_MS * 1000) {
+        return;
+    }
+    s_last_event_us = now;
+    node_log_event_t e;
+    memset(&e, 0, sizeof(e));
+    e.subtype = subtype;
+    e.a = a;
+    e.b = b;
+    append(NODE_LOG_TYPE_EVENT, &e, sizeof(e));
+}
+
+size_t node_log_read(uint8_t *out, size_t max_records, size_t skip)
+{
+    if (!s_active || !out || max_records == 0) return 0;
+    if (xSemaphoreTake(s_lock, pdMS_TO_TICKS(500)) != pdTRUE) return 0;
+
+    size_t written = 0;
+    for (size_t n = 0; n < s_count && written < max_records; n++) {
+        if (n < skip) continue;
+        /* newest-first: step back from head */
+        size_t idx = (s_head + NODE_LOG_MAX_RECORDS - 1 - n) % NODE_LOG_MAX_RECORDS;
+        if (fseek(s_fp, (long)(idx * NODE_LOG_RECORD_SIZE), SEEK_SET) != 0) break;
+        if (fread(out + written * NODE_LOG_RECORD_SIZE, 1, NODE_LOG_RECORD_SIZE, s_fp)
+            != NODE_LOG_RECORD_SIZE) break;
+        written++;
+    }
+    xSemaphoreGive(s_lock);
+    return written;
+}
+
+esp_err_t node_log_clear(void)
+{
+    if (!s_active) return ESP_ERR_INVALID_STATE;
+    if (xSemaphoreTake(s_lock, pdMS_TO_TICKS(1000)) != pdTRUE) return ESP_ERR_TIMEOUT;
+    esp_err_t err = ESP_OK;
+    if (s_fp) { fclose(s_fp); s_fp = NULL; }
+    s_fp = fopen(NODE_LOG_PATH, "w+b");
+    if (!s_fp) { s_active = false; err = ESP_FAIL; }
+    s_count = 0;
+    s_head = 0;
+    s_seq = 0;
+    xSemaphoreGive(s_lock);
+    return err;
+}
+
+#else /* CONFIG_ESPTOOLPY_FLASHSIZE_4MB */
+
+esp_err_t node_log_init(void) { return ESP_ERR_NOT_SUPPORTED; }
+bool node_log_is_active(void) { return false; }
+void node_log_boot(uint32_t reset_reason, uint32_t prev_uptime_s)
+{
+    (void)reset_reason;
+    (void)prev_uptime_s;
+}
+void node_log_periodic(void) { }
+void node_log_event(uint8_t subtype, int32_t a, int32_t b)
+{
+    (void)subtype;
+    (void)a;
+    (void)b;
+}
+void node_log_note_disconnect(uint8_t reason, int8_t rssi)
+{
+    (void)reason;
+    (void)rssi;
+}
+size_t node_log_read(uint8_t *out, size_t max_records, size_t skip)
+{
+    (void)out;
+    (void)max_records;
+    (void)skip;
+    return 0;
+}
+size_t node_log_count(void) { return 0; }
+uint16_t node_log_boot_id(void) { return 0; }
+esp_err_t node_log_clear(void) { return ESP_ERR_NOT_SUPPORTED; }
+
+#endif /* CONFIG_ESPTOOLPY_FLASHSIZE_4MB */
@@ -0,0 +1,114 @@
+/* Persistent on-node log -- survives a power cycle, readable without a cable.
+ *
+ * The problem this exists for (Joe, 2026-09-07): "a hung node ... doesnt do us
+ * any good for troubleshooting remotly because the unplug and mount results in
+ * a clearing of the condtion." Today the post-mortem for any remote fault is
+ * nothing: main.c decodes the reset reason at boot and logs it to the CONSOLE,
+ * which is exactly what a power cycle destroys.
+ *
+ * The flash was already partitioned for this and the features were off --
+ * partitions_16mb.csv reserves a 64K coredump partition and an 8000K storage
+ * FAT volume, neither of which had ever been mounted or written.
+ *
+ * # Retention, not wear, is the binding constraint
+ *
+ * 128 B records every 300 s fills 8 MB in ~222 days. Endurance at that rate is
+ * ~61,000 years, so the ring wraps 36 million times before the flash is at
+ * risk. The write rate is nonetheless bounded explicitly below, because flash
+ * wear is the one way this module can do harm.
+ *
+ * # Why uptime and boot_id rather than a timestamp
+ *
+ * These boards have no RTC. Nothing can be timestamped absolutely, so ordering
+ * comes from boot_id (incremented once per boot, persisted in NVS) plus
+ * uptime_s within that boot. That ordering survives a power cycle; a wall clock
+ * would not.
+ *
+ * # Counters are stored RAW
+ *
+ * Every counter here is cumulative and is written as-is. Differencing happens
+ * at read time. Storing rates instead would bake in the sampling interval and
+ * make every record useless the moment the cadence changed.
+ */
+#pragma once
+
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+
+#include "esp_err.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/** Every record is exactly this size, so the ring is index-addressable and a
+ *  reader never has to parse forward to find a boundary. */
+#define NODE_LOG_RECORD_SIZE 128
+
+/** Record types. A reader dispatches on this byte alone. */
+#define NODE_LOG_TYPE_PERIODIC 1
+#define NODE_LOG_TYPE_BOOT     2
+#define NODE_LOG_TYPE_EVENT    3
+
+/** Event subtypes. Periodic samples give the trend; these give the moment. */
+#define NODE_LOG_EV_WIFI_DISCONNECT 1
+#define NODE_LOG_EV_WIFI_RECONNECT  2
+#define NODE_LOG_EV_THERMAL_STATE   3
+#define NODE_LOG_EV_SEND_FAIL_RATE  4
+#define NODE_LOG_EV_WATCHDOG        5
+
+/** Mount the FAT volume and open the ring. Call once at boot, after NVS is up
+ *  (the boot counter lives there).
+ *
+ *  Failure is NOT fatal: on any error this module disables itself and every
+ *  other entry point becomes a no-op. A logging volume that will not mount must
+ *  never take the fleet down with it. */
+esp_err_t node_log_init(void);
+
+/** True when the ring mounted and writes are being accepted. */
+bool node_log_is_active(void);
+
+/** Append the boot record: reset reason, the previous session's final uptime,
+ *  and a health snapshot.
+ *
+ *  The highest-value record here. It catches a HANG FOLLOWED BY A WATCHDOG
+ *  RESET, which is the failure that bites this fleet and the one a coredump
+ *  does not capture. */
+void node_log_boot(uint32_t reset_reason, uint32_t prev_uptime_s);
+
+/** Append a periodic health sample. Rate-limited internally, so a caller cannot
+ *  wear the flash by calling it in a tight loop. */
+void node_log_periodic(void);
+
+/** Append an event record. a/b carry subtype-specific detail -- for a WiFi
+ *  disconnect they are the reason code and the RSSI at that moment, the pair
+ *  main.c currently logs only to the console. */
+void node_log_event(uint8_t subtype, int32_t a, int32_t b);
+
+/** Record a WiFi disconnect for the health snapshot's cumulative counters.
+ *  Kept as a setter so this module has no include cycle with main.c, which is
+ *  where the reason and RSSI are actually known. */
+void node_log_note_disconnect(uint8_t reason, int8_t rssi);
+
+/** Copy raw records into out, newest-first, for the HTTP reader.
+ *
+ *  @param out         destination, at least max_records * NODE_LOG_RECORD_SIZE
+ *  @param max_records maximum to copy
+ *  @param skip        how many of the newest to skip, so a caller can page
+ *  @return number of records written into out */
+size_t node_log_read(uint8_t *out, size_t max_records, size_t skip);
+
+/** Total records currently held in the ring. */
+size_t node_log_count(void);
+
+/** Boot id of the current session. Records from the same boot share it. */
+uint16_t node_log_boot_id(void);
+
+/** Erase every record. Deliberately explicit and never called automatically --
+ *  the whole point of the module is that state survives. */
+esp_err_t node_log_clear(void);
+
+#ifdef __cplusplus
+}
+#endif
@@ -109,7 +109,7 @@ void nvs_config_load(nvs_config_t *cfg)
    len = sizeof(buf);
    if (nvs_get_str(handle, "ssid", buf, &len) == ESP_OK && len > 1) {
        strlcpy(cfg->wifi_ssid, buf, sizeof(cfg->wifi_ssid));
-        ESP_LOGI(TAG, "NVS override: ssid=%s", cfg->wifi_ssid);
+        ESP_LOGI(TAG, "NVS override: ssid=<configured>");
    }

    /* WiFi password */
@@ -0,0 +1,204 @@
+#include "serial_onboarding.h"
+
+#include "serial_onboarding_protocol.h"
+
+#include <errno.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
+
+#include "esp_app_desc.h"
+#include "esp_efuse.h"
+#include "esp_log.h"
+#include "esp_mac.h"
+#include "esp_system.h"
+#include "esp_timer.h"
+#include "freertos/FreeRTOS.h"
+#include "freertos/task.h"
+#include "nvs.h"
+#include "psa/crypto.h"
+
+static const char *TAG = "serial_onboard";
+static nvs_config_t s_current_config;
+static char s_issued_nonce[RUVIEW_ONBOARDING_NONCE_HEX_LEN + 1];
+static int64_t s_nonce_issued_at_us;
+
+#define ONBOARDING_LINE_MAX 384
+#define ONBOARDING_NONCE_TTL_US (60LL * 1000LL * 1000LL)
+
+static const char *chip_name(void)
+{
+#if defined(CONFIG_IDF_TARGET_ESP32C6)
+    return "esp32c6";
+#elif defined(CONFIG_IDF_TARGET_ESP32S3)
+    return "esp32s3";
+#else
+    return "esp32";
+#endif
+}
+
+static void device_digest(char output[17])
+{
+    uint8_t base_mac[6] = {0};
+    uint8_t digest[32] = {0};
+    static const uint8_t domain[] = "ruview-device-v1";
+    uint8_t digest_input[sizeof(domain) - 1 + sizeof(base_mac)];
+    size_t digest_length = 0;
+    memcpy(digest_input, domain, sizeof(domain) - 1);
+    const esp_err_t mac_result = esp_efuse_mac_get_default(base_mac);
+    if (mac_result == ESP_OK) {
+        memcpy(digest_input + sizeof(domain) - 1, base_mac, sizeof(base_mac));
+    }
+    if (mac_result == ESP_OK &&
+        psa_crypto_init() == PSA_SUCCESS &&
+        psa_hash_compute(PSA_ALG_SHA_256, digest_input, sizeof(digest_input),
+                         digest, sizeof(digest), &digest_length) == PSA_SUCCESS &&
+        digest_length == sizeof(digest)) {
+        for (size_t index = 0; index < 8; index++) {
+            snprintf(output + index * 2, 3, "%02x", digest[index]);
+        }
+    } else {
+        memcpy(output, "0000000000000000", 17);
+    }
+}
+
+static void emit_hello(const char *nonce)
+{
+    const esp_app_desc_t *description = esp_app_get_description();
+    char digest[17] = {0};
+    device_digest(digest);
+    const bool configured = s_current_config.wifi_ssid[0] != '\0' &&
+                            s_current_config.target_ip[0] != '\0';
+    printf("RUVIEW_HELLO_OK_V1 nonce=%s chip=%s version=%s node_id=%u "
+           "target_ip=%s target_port=%u configured=%u device_digest=%s\n",
+           nonce, chip_name(), description->version,
+           (unsigned)s_current_config.node_id, s_current_config.target_ip,
+           (unsigned)s_current_config.target_port, configured ? 1U : 0U, digest);
+    fflush(stdout);
+}
+
+static esp_err_t commit_config(const ruview_onboarding_config_t *config)
+{
+    nvs_handle_t handle;
+    esp_err_t result = nvs_open("csi_cfg", NVS_READWRITE, &handle);
+    if (result != ESP_OK) return result;
+    if (!config->preserve_wifi) {
+        result = nvs_set_str(handle, "ssid", config->ssid);
+        if (result == ESP_OK) result = nvs_set_str(handle, "password", config->password);
+    }
+    if (result == ESP_OK) result = nvs_set_str(handle, "target_ip", config->target_ip);
+    if (result == ESP_OK) result = nvs_set_u16(handle, "target_port", config->target_port);
+    if (result == ESP_OK) result = nvs_set_u8(handle, "node_id", config->node_id);
+    if (result == ESP_OK) result = nvs_commit(handle);
+    nvs_close(handle);
+    return result;
+}
+
+static void process_line(char *line)
+{
+    char nonce[RUVIEW_ONBOARDING_NONCE_HEX_LEN + 1] = {0};
+    if (ruview_onboarding_parse_hello(line, nonce)) {
+        memcpy(s_issued_nonce, nonce, sizeof(s_issued_nonce));
+        s_nonce_issued_at_us = esp_timer_get_time();
+        emit_hello(nonce);
+        return;
+    }
+    if (strncmp(line, "RUVIEW_CONFIG_V1 ", 17) != 0) return;
+
+    ruview_onboarding_config_t request;
+    const ruview_onboarding_result_t parsed = ruview_onboarding_parse_config(line, &request);
+    if (parsed != RUVIEW_ONBOARDING_OK) {
+        printf("RUVIEW_CONFIG_ERR_V1 reason=%s\n", ruview_onboarding_result_name(parsed));
+        fflush(stdout);
+        return;
+    }
+    const int64_t age_us = esp_timer_get_time() - s_nonce_issued_at_us;
+    if (s_issued_nonce[0] == '\0' || strcmp(request.nonce, s_issued_nonce) != 0 ||
+        age_us < 0 || age_us > ONBOARDING_NONCE_TTL_US) {
+        printf("RUVIEW_CONFIG_ERR_V1 nonce=%s reason=claim_expired\n", request.nonce);
+        fflush(stdout);
+        return;
+    }
+    s_issued_nonce[0] = '\0';
+    const esp_err_t result = commit_config(&request);
+    if (result != ESP_OK) {
+        printf("RUVIEW_CONFIG_ERR_V1 nonce=%s reason=nvs_commit code=%s\n",
+               request.nonce, esp_err_to_name(result));
+        fflush(stdout);
+        return;
+    }
+
+    printf("RUVIEW_CONFIG_OK_V1 nonce=%s node_id=%u rebooting=1\n",
+           request.nonce, (unsigned)request.node_id);
+    fflush(stdout);
+    vTaskDelay(pdMS_TO_TICKS(400));
+    esp_restart();
+}
+
+static void consume_bytes(const uint8_t *input, ssize_t count, char *line,
+                          size_t *length, bool *overflow)
+{
+    for (ssize_t index = 0; index < count; index++) {
+        const uint8_t byte = input[index];
+        if (byte == '\r') continue;
+        if (byte == '\n') {
+            if (!*overflow && *length > 0) {
+                line[*length] = '\0';
+                process_line(line);
+            }
+            *length = 0;
+            *overflow = false;
+            continue;
+        }
+        if (byte < 0x20 || byte == 0x7f) continue;
+        if (*length + 1 < ONBOARDING_LINE_MAX) line[(*length)++] = (char)byte;
+        else *overflow = true;
+    }
+}
+
+static void serial_onboarding_task(void *argument)
+{
+    (void)argument;
+    const int original_flags = fcntl(STDIN_FILENO, F_GETFL, 0);
+    if (original_flags >= 0) (void)fcntl(STDIN_FILENO, F_SETFL, original_flags | O_NONBLOCK);
+    /* ESP-IDF secondary consoles mirror output but deliberately do not forward
+     * input to STDIN. Native S3/C6 USB Serial/JTAG therefore needs a bounded
+     * direct VFS reader while UART-console boards continue to use STDIN. */
+    const int usb_fd = open("/dev/secondary", O_RDONLY | O_NONBLOCK);
+    char primary_line[ONBOARDING_LINE_MAX];
+    char usb_line[ONBOARDING_LINE_MAX];
+    size_t primary_length = 0;
+    size_t usb_length = 0;
+    bool primary_overflow = false;
+    bool usb_overflow = false;
+    for (;;) {
+        uint8_t input[64];
+        const ssize_t count = read(STDIN_FILENO, input, sizeof(input));
+        if (count > 0) {
+            consume_bytes(input, count, primary_line, &primary_length, &primary_overflow);
+        }
+        else if (count < 0 && errno != EAGAIN && errno != EWOULDBLOCK) {
+            ESP_LOGW(TAG, "serial input unavailable: errno=%d", errno);
+            vTaskDelay(pdMS_TO_TICKS(500));
+        }
+        if (usb_fd >= 0) {
+            const ssize_t usb_count = read(usb_fd, input, sizeof(input));
+            if (usb_count > 0) {
+                consume_bytes(input, usb_count, usb_line, &usb_length, &usb_overflow);
+            }
+        }
+        vTaskDelay(pdMS_TO_TICKS(20));
+    }
+}
+
+esp_err_t serial_onboarding_start(const nvs_config_t *config)
+{
+    if (config == NULL) return ESP_ERR_INVALID_ARG;
+    memcpy(&s_current_config, config, sizeof(s_current_config));
+    const BaseType_t created = xTaskCreate(serial_onboarding_task, "serial_onboard",
+                                           4096, NULL, 4, NULL);
+    if (created != pdPASS) return ESP_ERR_NO_MEM;
+    ESP_LOGI(TAG, "bounded serial onboarding ready");
+    return ESP_OK;
+}
@@ -0,0 +1,15 @@
+#ifndef SERIAL_ONBOARDING_H
+#define SERIAL_ONBOARDING_H
+
+#include "esp_err.h"
+#include "nvs_config.h"
+
+/** Start the bounded USB serial onboarding listener.
+ *
+ * The listener exposes device metadata and accepts one nonce-bound
+ * configuration transaction. It never prints WiFi credentials and reboots
+ * only after a successful atomic NVS commit.
+ */
+esp_err_t serial_onboarding_start(const nvs_config_t *config);
+
+#endif
@@ -0,0 +1,214 @@
+#ifndef _POSIX_C_SOURCE
+#define _POSIX_C_SOURCE 200809L /* strtok_r under -std=c11 -pedantic on glibc */
+#endif
+#include "serial_onboarding_protocol.h"
+
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#define HELLO_COMMAND "RUVIEW_HELLO_V1"
+#define CONFIG_COMMAND "RUVIEW_CONFIG_V1"
+
+static bool valid_nonce(const char *value)
+{
+    if (value == NULL || strlen(value) != RUVIEW_ONBOARDING_NONCE_HEX_LEN) return false;
+    for (size_t index = 0; index < RUVIEW_ONBOARDING_NONCE_HEX_LEN; index++) {
+        const char c = value[index];
+        if (!((c >= '0' && c <= '9') || (c >= 'a' && c <= 'f') ||
+              (c >= 'A' && c <= 'F'))) return false;
+    }
+    return true;
+}
+
+static bool parse_u32(const char *value, uint32_t maximum, uint32_t *output)
+{
+    if (value == NULL || value[0] == '\0' || output == NULL) return false;
+    uint32_t result = 0;
+    for (const char *cursor = value; *cursor != '\0'; cursor++) {
+        if (*cursor < '0' || *cursor > '9') return false;
+        const uint32_t digit = (uint32_t)(*cursor - '0');
+        if (result > (maximum - digit) / 10U) return false;
+        result = result * 10U + digit;
+    }
+    *output = result;
+    return true;
+}
+
+static bool valid_ipv4(const char *value)
+{
+    if (value == NULL || value[0] == '\0' || strlen(value) > 15) return false;
+    unsigned octets = 0;
+    const char *cursor = value;
+    while (*cursor != '\0') {
+        if (octets == 4) return false;
+        if (*cursor == '.') return false;
+        uint32_t octet = 0;
+        unsigned digits = 0;
+        while (*cursor != '\0' && *cursor != '.') {
+            if (*cursor < '0' || *cursor > '9' || digits == 3) return false;
+            octet = octet * 10U + (uint32_t)(*cursor - '0');
+            if (octet > 255U) return false;
+            digits++;
+            cursor++;
+        }
+        if (digits == 0) return false;
+        octets++;
+        if (*cursor == '.') cursor++;
+    }
+    return octets == 4;
+}
+
+static bool valid_private_ipv4(const char *value)
+{
+    if (!valid_ipv4(value)) return false;
+    unsigned first = 0;
+    unsigned second = 0;
+    if (sscanf(value, "%u.%u", &first, &second) != 2) return false;
+    return first == 10U || (first == 172U && second >= 16U && second <= 31U) ||
+           (first == 192U && second == 168U);
+}
+
+static int base64_value(char c)
+{
+    if (c >= 'A' && c <= 'Z') return c - 'A';
+    if (c >= 'a' && c <= 'z') return c - 'a' + 26;
+    if (c >= '0' && c <= '9') return c - '0' + 52;
+    if (c == '+') return 62;
+    if (c == '/') return 63;
+    return -1;
+}
+
+static bool decode_base64(const char *encoded, uint8_t *output,
+                          size_t output_capacity, size_t *output_length)
+{
+    if (encoded == NULL || output == NULL || output_length == NULL) return false;
+    const size_t length = strlen(encoded);
+    if (length == 0 || length % 4 != 0) return false;
+    size_t written = 0;
+    for (size_t index = 0; index < length; index += 4) {
+        int values[4];
+        unsigned padding = 0;
+        for (unsigned offset = 0; offset < 4; offset++) {
+            const char c = encoded[index + offset];
+            if (c == '=') {
+                if (offset < 2 || index + 4 != length) return false;
+                values[offset] = 0;
+                padding++;
+            } else {
+                if (padding != 0) return false;
+                values[offset] = base64_value(c);
+                if (values[offset] < 0) return false;
+            }
+        }
+        if (padding > 2) return false;
+        const uint32_t block = ((uint32_t)values[0] << 18) |
+                               ((uint32_t)values[1] << 12) |
+                               ((uint32_t)values[2] << 6) |
+                               (uint32_t)values[3];
+        const unsigned bytes = 3U - padding;
+        if (written + bytes > output_capacity) return false;
+        output[written++] = (uint8_t)(block >> 16);
+        if (bytes > 1) output[written++] = (uint8_t)(block >> 8);
+        if (bytes > 2) output[written++] = (uint8_t)block;
+    }
+    *output_length = written;
+    return true;
+}
+
+static bool printable_secret(const uint8_t *bytes, size_t length)
+{
+    if (bytes == NULL) return false;
+    for (size_t index = 0; index < length; index++) {
+        if (bytes[index] < 0x20 || bytes[index] == 0x7f) return false;
+    }
+    return true;
+}
+
+int ruview_onboarding_parse_hello(
+    const char *line,
+    char nonce[RUVIEW_ONBOARDING_NONCE_HEX_LEN + 1])
+{
+    if (line == NULL || nonce == NULL) return 0;
+    const size_t prefix_length = strlen(HELLO_COMMAND);
+    if (strncmp(line, HELLO_COMMAND, prefix_length) != 0 || line[prefix_length] != ' ')
+        return 0;
+    const char *candidate = line + prefix_length + 1;
+    if (!valid_nonce(candidate)) return 0;
+    memcpy(nonce, candidate, RUVIEW_ONBOARDING_NONCE_HEX_LEN + 1);
+    return 1;
+}
+
+ruview_onboarding_result_t ruview_onboarding_parse_config(
+    const char *line,
+    ruview_onboarding_config_t *config)
+{
+    if (line == NULL || config == NULL || strlen(line) >= 384) return RUVIEW_ONBOARDING_ERR_FORMAT;
+    char copy[384];
+    memcpy(copy, line, strlen(line) + 1);
+
+    char *tokens[7] = {0};
+    size_t token_count = 0;
+    char *save = NULL;
+    for (char *token = strtok_r(copy, " ", &save); token != NULL;
+         token = strtok_r(NULL, " ", &save)) {
+        if (token_count == 7) return RUVIEW_ONBOARDING_ERR_FORMAT;
+        tokens[token_count++] = token;
+    }
+    if (token_count != 7 || strcmp(tokens[0], CONFIG_COMMAND) != 0)
+        return RUVIEW_ONBOARDING_ERR_FORMAT;
+    if (!valid_nonce(tokens[1])) return RUVIEW_ONBOARDING_ERR_NONCE;
+
+    uint32_t node_id = 0;
+    if (!parse_u32(tokens[2], 255, &node_id) || node_id == 0)
+        return RUVIEW_ONBOARDING_ERR_NODE_ID;
+    if (!valid_private_ipv4(tokens[3])) return RUVIEW_ONBOARDING_ERR_TARGET_IP;
+    uint32_t target_port = 0;
+    if (!parse_u32(tokens[4], 65535, &target_port) || target_port == 0)
+        return RUVIEW_ONBOARDING_ERR_TARGET_PORT;
+
+    const bool preserve_wifi = strcmp(tokens[5], "KEEP") == 0 &&
+                               strcmp(tokens[6], "KEEP") == 0;
+    if ((strcmp(tokens[5], "KEEP") == 0) != (strcmp(tokens[6], "KEEP") == 0))
+        return RUVIEW_ONBOARDING_ERR_FORMAT;
+    uint8_t ssid[RUVIEW_ONBOARDING_SSID_MAX_BYTES];
+    size_t ssid_length = 0;
+    if (!preserve_wifi && (!decode_base64(tokens[5], ssid, sizeof(ssid), &ssid_length) ||
+        ssid_length == 0 || !printable_secret(ssid, ssid_length)))
+        return RUVIEW_ONBOARDING_ERR_SSID;
+    uint8_t password[RUVIEW_ONBOARDING_PASSWORD_MAX_BYTES];
+    size_t password_length = 0;
+    if (!preserve_wifi && (!decode_base64(tokens[6], password, sizeof(password), &password_length) ||
+        password_length < 8 || !printable_secret(password, password_length)))
+        return RUVIEW_ONBOARDING_ERR_PASSWORD;
+
+    memset(config, 0, sizeof(*config));
+    memcpy(config->nonce, tokens[1], RUVIEW_ONBOARDING_NONCE_HEX_LEN + 1);
+    config->node_id = (uint8_t)node_id;
+    memcpy(config->target_ip, tokens[3], strlen(tokens[3]) + 1);
+    config->target_port = (uint16_t)target_port;
+    config->preserve_wifi = preserve_wifi;
+    if (!preserve_wifi) {
+        memcpy(config->ssid, ssid, ssid_length);
+        config->ssid[ssid_length] = '\0';
+        memcpy(config->password, password, password_length);
+        config->password[password_length] = '\0';
+    }
+    return RUVIEW_ONBOARDING_OK;
+}
+
+const char *ruview_onboarding_result_name(ruview_onboarding_result_t result)
+{
+    switch (result) {
+    case RUVIEW_ONBOARDING_OK: return "ok";
+    case RUVIEW_ONBOARDING_ERR_FORMAT: return "format";
+    case RUVIEW_ONBOARDING_ERR_NONCE: return "nonce";
+    case RUVIEW_ONBOARDING_ERR_NODE_ID: return "node_id";
+    case RUVIEW_ONBOARDING_ERR_TARGET_IP: return "target_ip";
+    case RUVIEW_ONBOARDING_ERR_TARGET_PORT: return "target_port";
+    case RUVIEW_ONBOARDING_ERR_SSID: return "ssid";
+    case RUVIEW_ONBOARDING_ERR_PASSWORD: return "password";
+    default: return "unknown";
+    }
+}
@@ -0,0 +1,42 @@
+#ifndef SERIAL_ONBOARDING_PROTOCOL_H
+#define SERIAL_ONBOARDING_PROTOCOL_H
+
+#include <stddef.h>
+#include <stdbool.h>
+#include <stdint.h>
+
+#define RUVIEW_ONBOARDING_NONCE_HEX_LEN 32
+#define RUVIEW_ONBOARDING_SSID_MAX_BYTES 32
+#define RUVIEW_ONBOARDING_PASSWORD_MAX_BYTES 63
+
+typedef struct {
+    char nonce[RUVIEW_ONBOARDING_NONCE_HEX_LEN + 1];
+    uint8_t node_id;
+    char target_ip[16];
+    uint16_t target_port;
+    bool preserve_wifi;
+    char ssid[RUVIEW_ONBOARDING_SSID_MAX_BYTES + 1];
+    char password[RUVIEW_ONBOARDING_PASSWORD_MAX_BYTES + 1];
+} ruview_onboarding_config_t;
+
+typedef enum {
+    RUVIEW_ONBOARDING_OK = 0,
+    RUVIEW_ONBOARDING_ERR_FORMAT,
+    RUVIEW_ONBOARDING_ERR_NONCE,
+    RUVIEW_ONBOARDING_ERR_NODE_ID,
+    RUVIEW_ONBOARDING_ERR_TARGET_IP,
+    RUVIEW_ONBOARDING_ERR_TARGET_PORT,
+    RUVIEW_ONBOARDING_ERR_SSID,
+    RUVIEW_ONBOARDING_ERR_PASSWORD,
+} ruview_onboarding_result_t;
+
+int ruview_onboarding_parse_hello(const char *line,
+                                  char nonce[RUVIEW_ONBOARDING_NONCE_HEX_LEN + 1]);
+
+ruview_onboarding_result_t ruview_onboarding_parse_config(
+    const char *line,
+    ruview_onboarding_config_t *config);
+
+const char *ruview_onboarding_result_name(ruview_onboarding_result_t result);
+
+#endif
@@ -0,0 +1,25 @@
+# ESP32-C6 CSI Node - 16MB flash partition table
+# For boards with 16MB flash (e.g. ESP32-C6 DevKitC-1 N16).
+#
+# Two 4MB OTA slots. The app is ~1.04MB, so the slots are far larger than
+# needed for the binary alone -- the size is chosen so an OTA never has to
+# care how much the image has grown, and it leaves room for a coredump
+# partition and an 8MB FAT volume for on-node storage.
+#
+# The 4MB and display layouts do not fit this: their slots are 1.875MB and
+# 2MB, sized for 4MB and 8MB parts respectively.
+#
+# Usage: set in sdkconfig, or use the matching defaults file:
+#   CONFIG_PARTITION_TABLE_CUSTOM_FILENAME="partitions_16mb.csv"
+#   idf.py -DSDKCONFIG_DEFAULTS="sdkconfig.defaults;sdkconfig.defaults.esp32c6;sdkconfig.defaults.16mb" build
+#
+# Verify before flashing an already-deployed node: a smaller table written
+# over a 16MB node relocates NVS and destroys its provisioning.
+# Name, Type, SubType, Offset, Size, Flags
+nvs,data,nvs,0x9000,24K,
+otadata,data,ota,0xf000,8K,
+phy_init,data,phy,0x11000,4K,
+ota_0,app,ota_0,0x20000,4M,
+ota_1,app,ota_1,0x420000,4M,
+coredump,data,coredump,0x820000,64K,
+storage,data,fat,0x830000,8000K,
@@ -6,3 +6,4 @@ phy_init,   data, phy,     0x11000,  0x1000,
 ota_0,      app,  ota_0,   0x20000,  0x200000,
 ota_1,      app,  ota_1,   0x220000, 0x200000,
 spiffs,     data, spiffs,  0x420000, 0x1E0000,
+storage,    data, fat,     0x600000, 0x200000,
@@ -0,0 +1,4 @@
+126a4b9f305e207aa2e0db93caf09e27f77b3bee4b4f618a0cb963f10a4364bc  bootloader.bin
+183c4557a93f6f0be1680f45988b7c7320130c8e0ed5d9c900add038d5cc84fb  esp32-csi-node.bin
+7d2c7ac4888bfd75cd5f56e8d61f69595121183afc81556c876732fd3782c62f  ota_data_initial.bin
+4c2cc4ffd52641e23b779bd57b3908014083ac3c1aab395756478c89e70d81f0  partition-table.bin
@@ -0,0 +1 @@
+�������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������Line truncated
@@ -0,0 +1,182 @@
+#!/usr/bin/env python3
+"""Run the gate factorial: U / M / S / MS, Latin-square blocked.
+
+Arms (NVS gate_mode, applied live -- no reboot):
+    0 U   elapsed-time gate, as upstream ships it
+    1 M   mesh-aligned bucket gate (ours, 4b54ef8e)
+    2 S   rx_seq selection + elapsed underneath
+    3 MS  both stacked
+
+Why it is built this way, and what each guard is for:
+
+* Every arm is applied to the WHOLE fleet, never to a subset. The stopped
+  2026-09-04 run compared four gated nodes against four different control
+  nodes; nodes differ, and that comparison could not be read.
+
+* After every switch the runner reads back `active.gate_mode` from EVERY node
+  and refuses to sample unless all nine agree. "Config was stored" is not
+  "gate is running" -- that gap is exactly what the previous run could not
+  distinguish from a null result.
+
+* Arms are short and blocked in a Latin square rather than run in long
+  sequential batches, so slow drift lands on all arms equally instead of being
+  aliased onto whichever arm ran first. Measured drift over 20 min windows is
+  sd 0.0045; counting noise is +/-0.002.
+
+* Metrics come from differenced cumulative counters, so the server is never
+  restarted and the fleet stays in production throughout.
+
+Output: arms_<label>.csv, one row per arm, in the fleet-baselines directory
+(outside git -- it carries presence information).
+"""
+import argparse, csv, json, os, sys, time, urllib.request
+
+PORT = 8032
+SERVER = "http://127.0.0.1:3000"
+OUTDIR = "C:/temp/ruview/fleet-baselines/gate-experiment"
+
+NODES = {0: "192.168.1.171", 1: "192.168.1.219", 2: "192.168.1.72",
+         3: "192.168.1.112", 4: "192.168.1.144", 5: "192.168.1.198",
+         6: "192.168.1.199", 7: "192.168.1.25",  8: "192.168.1.122"}
+
+ARM_NAME = {0: "U_elapsed", 1: "M_mesh", 2: "S_seq", 3: "MS_both"}
+
+# Latin square: every arm appears once per block, in a different position.
+BLOCKS = [[0, 1, 2, 3], [2, 3, 1, 0], [3, 0, 2, 1]]
+
+
+def key():
+    p = os.environ.get("RUVIEW_OTA_PSK_FILE")
+    if not p or not os.path.isfile(p):
+        sys.exit("set RUVIEW_OTA_PSK_FILE to the psk file path")
+    return open(p, encoding="utf-8").read().strip()
+
+
+def node_get(ip, path, k, timeout=10):
+    r = urllib.request.Request(f"http://{ip}:{PORT}{path}")
+    r.add_header("Authorization", "Bearer " + k)
+    with urllib.request.urlopen(r, timeout=timeout) as resp:
+        return json.load(resp)
+
+
+def node_post(ip, path, k, payload, timeout=15):
+    body = json.dumps(payload).encode()
+    r = urllib.request.Request(f"http://{ip}:{PORT}{path}", data=body)
+    r.add_header("Authorization", "Bearer " + k)
+    r.add_header("Content-Type", "application/json")
+    with urllib.request.urlopen(r, timeout=timeout) as resp:
+        return resp.status, resp.read().decode("utf-8", "replace")
+
+
+def srv(path):
+    with urllib.request.urlopen(SERVER + path, timeout=15) as r:
+        return json.load(r)
+
+
+def set_arm(mode, period, k):
+    """Apply an arm fleet-wide and PROVE every node is running it."""
+    for nid, ip in sorted(NODES.items()):
+        try:
+            node_post(ip, "/config", k, {"gate_mode": mode, "gate_seq_period": period})
+        except Exception as e:
+            print(f"  n{nid} set FAILED: {e}", file=sys.stderr)
+    time.sleep(5)
+    bad = []
+    for nid, ip in sorted(NODES.items()):
+        try:
+            act = node_get(ip, "/config", k).get("active", {})
+            if act.get("gate_mode") != mode or act.get("gate_seq_period") != period:
+                bad.append((nid, act))
+        except Exception as e:
+            bad.append((nid, str(e)))
+    return bad
+
+
+def snapshot():
+    f = srv("/api/v1/fusion")
+    m = srv("/api/v1/mesh")["nodes"]
+    nodes = {}
+    for k2, v in m.items():
+        tx = v.get("health", {}).get("tx", {})
+        nodes[k2] = {"acc": v.get("csi_fps_samples"), "ed": tx.get("early_drop"),
+                     "fps": v.get("csi_fps_ema"), "valid": v.get("is_valid")}
+    pairs = {f"{p['a']}-{p['b']}": p["common"] for p in f.get("pairs", [])}
+    return {"t": time.time(), "observations": f["observations"],
+            "transmissions": f["transmissions"], "paired": f["paired"],
+            "nodes": nodes, "pairs": pairs}
+
+
+def main():
+    ap = argparse.ArgumentParser()
+    ap.add_argument("--label", default="factorial")
+    ap.add_argument("--arm-minutes", type=float, default=20.0)
+    ap.add_argument("--settle-minutes", type=float, default=3.0)
+    ap.add_argument("--period", type=int, default=8)
+    ap.add_argument("--blocks", type=int, default=3)
+    a = ap.parse_args()
+
+    k = key()
+    os.makedirs(OUTDIR, exist_ok=True)
+    out = os.path.join(OUTDIR, f"arms_{a.label}.csv")
+    new = not os.path.exists(out)
+    fh = open(out, "a", newline="", encoding="utf-8")
+    w = csv.writer(fh)
+    if new:
+        w.writerow(["block", "arm", "arm_name", "period", "start_iso", "end_iso",
+                    "dur_s", "d_observations", "d_transmissions", "d_paired",
+                    "paired_fraction", "node_json", "pairs_json", "verified"])
+        fh.flush()
+
+    print(f"gate factorial: {a.blocks} blocks x 4 arms x {a.arm_minutes:g} min "
+          f"(+{a.settle_minutes:g} min settle), seq period {a.period}")
+    print(f"est. total {a.blocks*4*(a.arm_minutes+a.settle_minutes)/60:.1f} h -> {out}\n")
+
+    for bi in range(a.blocks):
+        order = BLOCKS[bi % len(BLOCKS)]
+        print(f"--- block {bi}: {' '.join(ARM_NAME[m] for m in order)} ---")
+        for mode in order:
+            print(f"[{time.strftime('%H:%M:%S')}] arm {ARM_NAME[mode]} ...", flush=True)
+            bad = set_arm(mode, a.period, k)
+            if bad:
+                print(f"  WARNING not all nodes on arm: {bad}", file=sys.stderr)
+            # Settle: the gate changes instantly, but csi_fps_ema and the
+            # fusion pairing window carry the previous arm for a while.
+            time.sleep(a.settle_minutes * 60)
+            s0 = snapshot()
+            time.sleep(a.arm_minutes * 60)
+            s1 = snapshot()
+
+            dtr = s1["transmissions"] - s0["transmissions"]
+            dp = s1["paired"] - s0["paired"]
+            pf = dp / dtr if dtr > 0 else float("nan")
+            nodes = {}
+            for nid in s1["nodes"]:
+                if nid in s0["nodes"]:
+                    dacc = (s1["nodes"][nid]["acc"] or 0) - (s0["nodes"][nid]["acc"] or 0)
+                    ded = (s1["nodes"][nid]["ed"] or 0) - (s0["nodes"][nid]["ed"] or 0)
+                    nodes[nid] = {"d_acc": dacc, "d_ed": ded,
+                                  "R": round((dacc + ded) / dacc, 3) if dacc > 0 else None,
+                                  "fps": round(s1["nodes"][nid]["fps"] or 0, 2),
+                                  "valid": s1["nodes"][nid]["valid"]}
+            dpairs = {kk: s1["pairs"].get(kk, 0) - s0["pairs"].get(kk, 0)
+                      for kk in s1["pairs"]}
+            w.writerow([bi, mode, ARM_NAME[mode], a.period,
+                        time.strftime("%Y-%m-%dT%H:%M:%S", time.localtime(s0["t"])),
+                        time.strftime("%Y-%m-%dT%H:%M:%S", time.localtime(s1["t"])),
+                        round(s1["t"] - s0["t"]),
+                        s1["observations"] - s0["observations"], dtr, dp,
+                        f"{pf:.6f}",
+                        json.dumps(nodes, separators=(",", ":")),
+                        json.dumps(dpairs, separators=(",", ":")),
+                        "no" if bad else "yes"])
+            fh.flush()
+            meanR = [v["R"] for v in nodes.values() if v["R"]]
+            print(f"    paired_fraction={pf:.4f}  transmissions={dtr}  "
+                  f"meanR={sum(meanR)/len(meanR):.2f}" if meanR else "", flush=True)
+
+    fh.close()
+    print("done")
+
+
+if __name__ == "__main__":
+    main()
@@ -0,0 +1,41 @@
+# ESP32-C6 CSI Node - 16MB Flash SDK Configuration
+# For boards with 16MB flash (e.g. ESP32-C6 DevKitC-1 N16).
+#
+# Layered on top of sdkconfig.defaults.esp32c6, which keeps a 4MB layout
+# because 4MB C6 devkits are the common case and must not be silently
+# repartitioned by inheriting this.
+#
+# Build:
+#   idf.py -DSDKCONFIG_DEFAULTS="sdkconfig.defaults;sdkconfig.defaults.esp32c6;sdkconfig.defaults.16mb" build
+#
+# Confirm before flashing a deployed node: /ota/status must report
+# max_size 4194304. Writing a smaller table over a 16MB node relocates NVS
+# and destroys its provisioning.
+
+CONFIG_ESPTOOLPY_FLASHSIZE_16MB=y
+CONFIG_ESPTOOLPY_FLASHSIZE="16MB"
+CONFIG_PARTITION_TABLE_CUSTOM=y
+CONFIG_PARTITION_TABLE_CUSTOM_FILENAME="partitions_16mb.csv"
+
+# Firmware rollback: an OTA'd image boots PENDING_VERIFY and must confirm
+# itself, or the bootloader reverts on the next boot. See ota_rollback_* in
+# ota_update.c for when confirmation happens and why.
+CONFIG_BOOTLOADER_APP_ROLLBACK_ENABLE=y
+
+# Coredump to flash. The 64K `coredump` partition has existed in
+# partitions_16mb.csv since the 16MB layout was written and has never held
+# anything, because the build defaulted to
+# CONFIG_ESP_COREDUMP_ENABLE_TO_NONE=y. A panic therefore left no stack trace
+# on a fleet whose faults are all remote.
+#
+# Complementary to the on-node log, not a substitute: a coredump captures a
+# CRASH, and the log's boot record captures a HANG followed by a watchdog
+# reset -- which is the failure this fleet actually sees.
+CONFIG_ESP_COREDUMP_ENABLE_TO_FLASH=y
+CONFIG_ESP_COREDUMP_DATA_FORMAT_ELF=y
+CONFIG_ESP_COREDUMP_CHECKSUM_CRC32=y
+CONFIG_ESP_COREDUMP_LOGS=y
+
+# The `storage` FAT volume (8000K) that node_log.c mounts. Reserved in the
+# same partition table and likewise never used until now.
+CONFIG_WL_SECTOR_SIZE_4096=y
@@ -0,0 +1,4 @@
+# Seeed XIAO ESP32-C6 external U.FL antenna test overlay.
+# Use only with the XIAO board; generic C6 boards may use GPIO3/GPIO14.
+CONFIG_C6_XIAO_ANTENNA_SELECT=y
+CONFIG_C6_XIAO_ANTENNA_EXTERNAL=y
@@ -0,0 +1,4 @@
+# Seeed XIAO ESP32-C6 internal ceramic antenna test overlay.
+# Keeps RF-switch control enabled so the boot log proves the selected path.
+CONFIG_C6_XIAO_ANTENNA_SELECT=y
+CONFIG_C6_XIAO_ANTENNA_INTERNAL=y
@@ -39,16 +39,45 @@ CFLAGS   = -fsanitize=fuzzer,address,undefined -g -O1 \
 STUBS_SRC = stubs/esp_stubs.c
 MAIN_DIR  = ../main

+# GNU ld and Apple's ld spell dead section elimination differently.
+# Keep the host sanitation test portable across the Linux CI runner and macOS.
+UNAME_S := $(shell uname -s)
+ifeq ($(UNAME_S),Darwin)
+DEAD_STRIP_LDFLAGS := -Wl,-dead_strip
+else
+DEAD_STRIP_LDFLAGS := -Wl,--gc-sections
+endif
+
 # Default fuzz duration (seconds) and jobs
 FUZZ_DURATION ?= 30
 FUZZ_JOBS     ?= 1

 .PHONY: all clean run_serialize run_edge run_nvs run_all test_adr110 run_adr110 \
        test_vitals run_vitals test_mmwave_detect run_mmwave_detect host_tests \
-        test_thermal run_thermal
+        test_thermal run_thermal test_csi_sanitize run_csi_sanitize \
+        test_c6_antenna run_c6_antenna test_serial_onboarding run_serial_onboarding

 all: fuzz_serialize fuzz_edge fuzz_nvs test_adr110 test_vitals test_mmwave_detect \
-     test_thermal
+     test_thermal test_csi_sanitize test_c6_antenna test_serial_onboarding
+
+# --- XIAO ESP32-C6 RF switch selection ---
+# Host-side truth table for the GPIO14 antenna selector. GPIO3 is always driven
+# low by the device implementation before this level is applied.
+test_c6_antenna: test_c6_antenna_select.c $(MAIN_DIR)/c6_antenna_select.h
+	cc -std=c99 -Wall -Wextra -I$(MAIN_DIR) -o $@ $<
+
+run_c6_antenna: test_c6_antenna
+	./test_c6_antenna
+
+# --- ESP-IDF invalid first-word sanitation ---
+# Links the production serializer. Function sections and dead stripping keep
+# unrelated device-only callback code out of this host executable.
+test_csi_sanitize: test_csi_sanitize.c $(MAIN_DIR)/csi_collector.c $(STUBS_SRC)
+	cc -std=c99 -Wall -Wextra -Istubs -I$(MAIN_DIR) -ffunction-sections \
+		$^ $(DEAD_STRIP_LDFLAGS) -o $@ -lm
+
+run_csi_sanitize: test_csi_sanitize
+	./test_csi_sanitize

 # --- ADR-110 encoding unit tests ---
 # Host-side, no libFuzzer needed — plain C99 deterministic table tests
@@ -93,8 +122,19 @@ test_thermal: test_thermal_hysteresis.c $(MAIN_DIR)/thermal.h
 run_thermal: test_thermal
 	./test_thermal

-host_tests: run_adr110 run_vitals run_mmwave_detect run_thermal
-	@echo "Host tests passed (ADR-110 + vitals #998/#996 + mmwave detect #1135 + thermal)"
+# --- Native Mac USB onboarding protocol ---
+# Tests the production parser and secret validation without ESP-IDF. This pins
+# nonce shape, IPv4 and node bounds, base64 handling, and control-byte denial.
+test_serial_onboarding: test_serial_onboarding_protocol.c $(MAIN_DIR)/serial_onboarding_protocol.c $(MAIN_DIR)/serial_onboarding_protocol.h
+	cc -std=c11 -Wall -Wextra -Werror -pedantic -I$(MAIN_DIR) -o $@ \
+		test_serial_onboarding_protocol.c $(MAIN_DIR)/serial_onboarding_protocol.c
+
+run_serial_onboarding: test_serial_onboarding
+	./test_serial_onboarding
+
+host_tests: run_adr110 run_vitals run_mmwave_detect run_thermal run_csi_sanitize \
+            run_c6_antenna run_serial_onboarding
+	@echo "Host tests passed (ADR-110 + CSI sanitation + vitals + mmwave + thermal + C6 antenna + USB onboarding)"

 # --- Serialize fuzzer ---
 # Tests csi_serialize_frame() with random wifi_csi_info_t inputs.
@@ -130,5 +170,6 @@ run_nvs: fuzz_nvs
 run_all: run_serialize run_edge run_nvs

 clean:
-	rm -f fuzz_serialize fuzz_edge fuzz_nvs test_adr110 test_vitals
+	rm -f fuzz_serialize fuzz_edge fuzz_nvs test_adr110 test_vitals test_mmwave_detect \
+		test_thermal test_csi_sanitize test_c6_antenna test_serial_onboarding
 	rm -rf corpus_serialize/ corpus_edge/ corpus_nvs/
@@ -90,6 +90,7 @@ int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size)
    info.rx_ctrl.sig_mode      = legacy_inputs & 0x03;
    info.rx_ctrl.cwb           = (legacy_inputs >> 2) & 0x01;
    info.rx_ctrl.stbc          = (legacy_inputs >> 3) & 0x01;
+    info.first_word_invalid    = (test_case & 0x80) != 0;

    /* Use remaining fuzz data as I/Q buffer content. */
    uint16_t iq_len;
@@ -136,6 +137,17 @@ int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size)
    if (result > out_len) {
        __builtin_trap();  /* Buffer overflow detected. */
    }
+    if (result >= CSI_HEADER_SIZE + iq_len && info.first_word_invalid && iq_len > 0) {
+        size_t invalid_len = iq_len < 4 ? iq_len : 4;
+        for (size_t i = 0; i < invalid_len; i++) {
+            if (out_buf[CSI_HEADER_SIZE + i] != 0) {
+                __builtin_trap();  /* Invalid hardware prefix escaped sanitation. */
+            }
+        }
+        if ((out_buf[19] & CSI_FLAG_FIRST_WORD_SANITIZED) == 0) {
+            __builtin_trap();  /* Sanitized payload must carry provenance. */
+        }
+    }

    /* --- Test case 1: NULL info pointer --- */
    if (test_case & 0x01) {
@@ -90,6 +90,7 @@ typedef struct {
 typedef struct {
    wifi_pkt_rx_ctrl_t rx_ctrl;
    uint8_t            mac[6];
+    bool               first_word_invalid;
    int16_t            len;     /**< Length of the I/Q buffer in bytes. */
    int8_t            *buf;     /**< Pointer to I/Q data. */
 } wifi_csi_info_t;
@@ -0,0 +1,13 @@
+#include <assert.h>
+#include <stdio.h>
+
+#include "c6_antenna_select.h"
+
+int main(void)
+{
+    assert(c6_xiao_antenna_gpio14_level(C6_XIAO_ANTENNA_INTERNAL) == 0);
+    assert(c6_xiao_antenna_gpio14_level(C6_XIAO_ANTENNA_EXTERNAL) == 1);
+
+    puts("PASS: XIAO ESP32-C6 antenna selection truth table");
+    return 0;
+}
@@ -0,0 +1,56 @@
+/** Deterministic host test for ESP-IDF first_word_invalid sanitation. */
+
+#include "esp_stubs.h"
+#include "nvs_config.h"
+#include "csi_collector.h"
+
+#include <assert.h>
+#include <stdio.h>
+#include <string.h>
+
+nvs_config_t g_nvs_config;
+
+static void make_info(wifi_csi_info_t *info, int8_t *iq, uint16_t len, bool invalid)
+{
+    memset(info, 0, sizeof(*info));
+    info->rx_ctrl.channel = 6;
+    info->rx_ctrl.rssi = -42;
+    info->rx_ctrl.noise_floor = -91;
+    info->len = (int16_t)len;
+    info->buf = iq;
+    info->first_word_invalid = invalid;
+}
+
+int main(void)
+{
+    int8_t iq[] = {1, 2, 3, 4, 5, 6, 7, 8};
+    uint8_t frame[CSI_MAX_FRAME_SIZE];
+    wifi_csi_info_t info;
+
+    make_info(&info, iq, sizeof(iq), true);
+    size_t len = csi_serialize_frame(&info, frame, sizeof(frame));
+    assert(len == CSI_HEADER_SIZE + sizeof(iq));
+    assert(frame[CSI_HEADER_SIZE] == 0);
+    assert(frame[CSI_HEADER_SIZE + 1] == 0);
+    assert(frame[CSI_HEADER_SIZE + 2] == 0);
+    assert(frame[CSI_HEADER_SIZE + 3] == 0);
+    assert(frame[CSI_HEADER_SIZE + 4] == 5);
+    assert((frame[19] & CSI_FLAG_FIRST_WORD_SANITIZED) != 0);
+
+    make_info(&info, iq, sizeof(iq), false);
+    len = csi_serialize_frame(&info, frame, sizeof(frame));
+    assert(len == CSI_HEADER_SIZE + sizeof(iq));
+    assert(memcmp(&frame[CSI_HEADER_SIZE], iq, sizeof(iq)) == 0);
+    assert((frame[19] & CSI_FLAG_FIRST_WORD_SANITIZED) == 0);
+
+    int8_t short_iq[] = {9, 10};
+    make_info(&info, short_iq, sizeof(short_iq), true);
+    len = csi_serialize_frame(&info, frame, sizeof(frame));
+    assert(len == CSI_HEADER_SIZE + sizeof(short_iq));
+    assert(frame[CSI_HEADER_SIZE] == 0);
+    assert(frame[CSI_HEADER_SIZE + 1] == 0);
+    assert((frame[19] & CSI_FLAG_FIRST_WORD_SANITIZED) != 0);
+
+    puts("CSI invalid-prefix sanitation: PASS");
+    return 0;
+}
@@ -0,0 +1,68 @@
+#include <assert.h>
+#include <stdio.h>
+#include <string.h>
+
+#include "../main/serial_onboarding_protocol.h"
+
+static void test_hello(void)
+{
+    char nonce[33] = {0};
+    assert(ruview_onboarding_parse_hello(
+        "RUVIEW_HELLO_V1 00112233445566778899aabbccddeeff", nonce));
+    assert(strcmp(nonce, "00112233445566778899aabbccddeeff") == 0);
+    assert(!ruview_onboarding_parse_hello("RUVIEW_HELLO_V1 bad", nonce));
+    assert(!ruview_onboarding_parse_hello(
+        "RUVIEW_HELLO_V1 00112233445566778899aabbccddeeff extra", nonce));
+}
+
+static void test_config(void)
+{
+    ruview_onboarding_config_t config;
+    assert(ruview_onboarding_parse_config(
+        "RUVIEW_CONFIG_V1 00112233445566778899aabbccddeeff 5 192.168.1.166 5005 "
+        "UnVWaWV3IExhYg== U3Ryb25nUGFzc3dvcmQ=", &config) == RUVIEW_ONBOARDING_OK);
+    assert(config.node_id == 5);
+    assert(config.target_port == 5005);
+    assert(strcmp(config.target_ip, "192.168.1.166") == 0);
+    assert(strcmp(config.ssid, "RuView Lab") == 0);
+    assert(strcmp(config.password, "StrongPassword") == 0);
+    assert(!config.preserve_wifi);
+    assert(ruview_onboarding_parse_config(
+        "RUVIEW_CONFIG_V1 00112233445566778899aabbccddeeff 6 192.168.1.166 5005 KEEP KEEP",
+        &config) == RUVIEW_ONBOARDING_OK);
+    assert(config.preserve_wifi);
+}
+
+static void test_rejections(void)
+{
+    ruview_onboarding_config_t config;
+    const char *prefix = "RUVIEW_CONFIG_V1 00112233445566778899aabbccddeeff";
+    char line[512];
+    snprintf(line, sizeof(line), "%s 0 192.168.1.2 5005 UnVWaWV3 U3Ryb25nUGFzc3dvcmQ=", prefix);
+    assert(ruview_onboarding_parse_config(line, &config) == RUVIEW_ONBOARDING_ERR_NODE_ID);
+    snprintf(line, sizeof(line), "%s 5 999.1.1.1 5005 UnVWaWV3 U3Ryb25nUGFzc3dvcmQ=", prefix);
+    assert(ruview_onboarding_parse_config(line, &config) == RUVIEW_ONBOARDING_ERR_TARGET_IP);
+    snprintf(line, sizeof(line), "%s 5 8.8.8.8 5005 UnVWaWV3 U3Ryb25nUGFzc3dvcmQ=", prefix);
+    assert(ruview_onboarding_parse_config(line, &config) == RUVIEW_ONBOARDING_ERR_TARGET_IP);
+    snprintf(line, sizeof(line), "%s 5 172.32.0.1 5005 UnVWaWV3 U3Ryb25nUGFzc3dvcmQ=", prefix);
+    assert(ruview_onboarding_parse_config(line, &config) == RUVIEW_ONBOARDING_ERR_TARGET_IP);
+    snprintf(line, sizeof(line), "%s 5 192.168.1.2 0 UnVWaWV3 U3Ryb25nUGFzc3dvcmQ=", prefix);
+    assert(ruview_onboarding_parse_config(line, &config) == RUVIEW_ONBOARDING_ERR_TARGET_PORT);
+    snprintf(line, sizeof(line), "%s 5 192.168.1.2 5005 !!!! U3Ryb25nUGFzc3dvcmQ=", prefix);
+    assert(ruview_onboarding_parse_config(line, &config) == RUVIEW_ONBOARDING_ERR_SSID);
+    snprintf(line, sizeof(line), "%s 5 192.168.1.2 5005 UnVWaWV3 c2hvcnQ=", prefix);
+    assert(ruview_onboarding_parse_config(line, &config) == RUVIEW_ONBOARDING_ERR_PASSWORD);
+    snprintf(line, sizeof(line), "%s 5 192.168.1.2 5005 UnVWaWV3 UGFzc3dvcmQxCg==", prefix);
+    assert(ruview_onboarding_parse_config(line, &config) == RUVIEW_ONBOARDING_ERR_PASSWORD);
+    snprintf(line, sizeof(line), "%s 5 192.168.1.2 5005 KEEP U3Ryb25nUGFzc3dvcmQ=", prefix);
+    assert(ruview_onboarding_parse_config(line, &config) == RUVIEW_ONBOARDING_ERR_FORMAT);
+}
+
+int main(void)
+{
+    test_hello();
+    test_config();
+    test_rejections();
+    puts("serial onboarding protocol tests passed");
+    return 0;
+}
@@ -1 +1 @@
-0.8.8
+0.8.12
@@ -0,0 +1,201 @@
+#!/usr/bin/env python3
+"""
+RTL8721Dx (Realtek AmebaDplus) live CSI throughput/latency benchmark.
+
+Listens on the wifi-densepose-sensing-server's CSI UDP port for real RAC1
+frames (ADR-323, docs/adr/ADR-323-rtl8721dx-ameba-csi-wire-protocol.md) sent
+by the ruview_csi_node firmware (branch feat/rtl8721dx-csi-bringup) running
+on real RTL8721Dx hardware, and reports MEASURED — not simulated — throughput
+and frame-rate statistics.
+
+This does not itself trigger a board reset; run it while the firmware is
+already connected and streaming (see CLAUDE.local.md for the reset+capture
+pattern used to bring a fresh boot up during firmware iteration).
+
+Usage:
+    python scripts/benchmark-rtl8721dx-csi.py --duration 40
+    python scripts/benchmark-rtl8721dx-csi.py --duration 40 --port 5005 --output results.json
+"""
+
+from __future__ import annotations
+
+import argparse
+import json
+import socket
+import struct
+import sys
+import time
+from dataclasses import dataclass, asdict, field
+from pathlib import Path
+
+RAC1_MAGIC = bytes.fromhex("52414331")  # "RAC1" little-endian, see ADR-323
+RHB1_MAGIC = bytes.fromhex("52484231")  # heartbeat marker (not a CSI frame)
+RAC1_HEADER_LEN = 49
+
+
+@dataclass
+class Rac1Frame:
+    recv_time: float
+    length: int
+    sequence: int
+    timestamp_us: int
+    channel: int
+    bandwidth: int
+    num_sub_carrier: int
+    rssi_dbm: int
+    csi_valid: int
+
+
+def parse_rac1_header(data: bytes, recv_time: float) -> Rac1Frame | None:
+    if len(data) < RAC1_HEADER_LEN or data[:4] != RAC1_MAGIC:
+        return None
+    sequence = struct.unpack_from("<I", data, 13)[0]
+    timestamp_us = struct.unpack_from("<I", data, 17)[0]
+    channel = data[33]
+    bandwidth = data[34]
+    num_sub_carrier = struct.unpack_from("<H", data, 37)[0]
+    rssi_dbm = struct.unpack_from("<b", data, 41)[0]
+    csi_valid = data[43]
+    return Rac1Frame(
+        recv_time=recv_time,
+        length=len(data),
+        sequence=sequence,
+        timestamp_us=timestamp_us,
+        channel=channel,
+        bandwidth=bandwidth,
+        num_sub_carrier=num_sub_carrier,
+        rssi_dbm=rssi_dbm,
+        csi_valid=csi_valid,
+    )
+
+
+@dataclass
+class BenchmarkResult:
+    duration_s: float
+    total_datagrams: int
+    rac1_frames: int
+    heartbeat_packets: int
+    other_packets: int
+    rac1_bytes: int
+    rac1_fps: float
+    rac1_bytes_per_sec: float
+    sequence_gaps: int
+    first_sequence: int | None
+    last_sequence: int | None
+    rssi_min_dbm: int | None
+    rssi_max_dbm: int | None
+    rssi_mean_dbm: float | None
+    inter_frame_interval_ms_mean: float | None
+    inter_frame_interval_ms_p95: float | None
+    channels_seen: list[int] = field(default_factory=list)
+    evidence: str = "MEASURED"
+
+
+def run_benchmark(port: int, duration: float, bind_ip: str = "0.0.0.0") -> BenchmarkResult:
+    sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
+    sock.bind((bind_ip, port))
+    sock.settimeout(0.5)
+
+    frames: list[Rac1Frame] = []
+    total = 0
+    heartbeats = 0
+    other = 0
+
+    deadline = time.time() + duration
+    print(f"Listening on {bind_ip}:{port} for {duration}s ...", file=sys.stderr)
+    while time.time() < deadline:
+        try:
+            data, _addr = sock.recvfrom(4096)
+        except socket.timeout:
+            continue
+        recv_time = time.time()
+        total += 1
+        if data[:4] == RHB1_MAGIC:
+            heartbeats += 1
+            continue
+        frame = parse_rac1_header(data, recv_time)
+        if frame is not None:
+            frames.append(frame)
+        else:
+            other += 1
+    sock.close()
+
+    rac1_bytes = sum(f.length for f in frames)
+    seqs = [f.sequence for f in frames]
+    rssis = [f.rssi_dbm for f in frames]
+    channels = sorted({f.channel for f in frames})
+
+    gaps = 0
+    for a, b in zip(seqs, seqs[1:]):
+        if b != a + 1:
+            gaps += 1
+
+    intervals_ms = [
+        (b.recv_time - a.recv_time) * 1000.0 for a, b in zip(frames, frames[1:])
+    ]
+    intervals_ms.sort()
+
+    def percentile(values: list[float], p: float) -> float | None:
+        if not values:
+            return None
+        idx = min(len(values) - 1, int(len(values) * p))
+        return values[idx]
+
+    return BenchmarkResult(
+        duration_s=duration,
+        total_datagrams=total,
+        rac1_frames=len(frames),
+        heartbeat_packets=heartbeats,
+        other_packets=other,
+        rac1_bytes=rac1_bytes,
+        rac1_fps=len(frames) / duration if duration > 0 else 0.0,
+        rac1_bytes_per_sec=rac1_bytes / duration if duration > 0 else 0.0,
+        sequence_gaps=gaps,
+        first_sequence=seqs[0] if seqs else None,
+        last_sequence=seqs[-1] if seqs else None,
+        rssi_min_dbm=min(rssis) if rssis else None,
+        rssi_max_dbm=max(rssis) if rssis else None,
+        rssi_mean_dbm=(sum(rssis) / len(rssis)) if rssis else None,
+        inter_frame_interval_ms_mean=(
+            sum(intervals_ms) / len(intervals_ms) if intervals_ms else None
+        ),
+        inter_frame_interval_ms_p95=percentile(intervals_ms, 0.95),
+        channels_seen=channels,
+    )
+
+
+def main() -> int:
+    parser = argparse.ArgumentParser(description=__doc__, formatter_class=argparse.RawDescriptionHelpFormatter)
+    parser.add_argument("--port", type=int, default=5005, help="UDP port to listen on (default: 5005, matches wifi-densepose-sensing-server)")
+    parser.add_argument("--bind-ip", type=str, default="0.0.0.0")
+    parser.add_argument("--duration", type=float, default=40.0, help="capture window in seconds")
+    parser.add_argument("--output", type=Path, default=None, help="write results as JSON to this path")
+    args = parser.parse_args()
+
+    result = run_benchmark(args.port, args.duration, args.bind_ip)
+
+    print(f"\n=== RTL8721Dx RAC1 CSI benchmark ({result.evidence}) ===")
+    print(f"duration:              {result.duration_s:.1f}s")
+    print(f"total UDP datagrams:   {result.total_datagrams}")
+    print(f"RAC1 CSI frames:       {result.rac1_frames}")
+    print(f"heartbeat packets:     {result.heartbeat_packets}")
+    print(f"other/unrecognized:    {result.other_packets}")
+    print(f"RAC1 throughput:       {result.rac1_fps:.2f} fps, {result.rac1_bytes_per_sec:.1f} bytes/s")
+    print(f"sequence gaps:         {result.sequence_gaps} (dropped/reordered frames)")
+    if result.first_sequence is not None:
+        print(f"sequence range:        {result.first_sequence} .. {result.last_sequence}")
+    if result.rssi_mean_dbm is not None:
+        print(f"RSSI:                  min={result.rssi_min_dbm} max={result.rssi_max_dbm} mean={result.rssi_mean_dbm:.1f} dBm")
+    if result.inter_frame_interval_ms_mean is not None:
+        print(f"inter-frame interval:  mean={result.inter_frame_interval_ms_mean:.1f}ms p95={result.inter_frame_interval_ms_p95:.1f}ms")
+    print(f"channels seen:         {result.channels_seen}")
+
+    if args.output:
+        args.output.write_text(json.dumps(asdict(result), indent=2))
+        print(f"\nwrote {args.output}", file=sys.stderr)
+
+    return 0
+
+
+if __name__ == "__main__":
+    sys.exit(main())
@@ -1166,11 +1166,21 @@ async function main() {
  // We iterate over triplets, compute gradients via computeGradient(), and apply
  // them to update the encoder's w2 layer (the embedding projection layer).
  console.log('  Applying gradient updates to encoder weights...');
+  // Same bug class as lossHistory: contrastiveResult.durationMs times the
+  // no-op contrastiveTrainer.train() baseline pass above, not this loop --
+  // the actual gradient-update work. Time it here instead.
+  const contrastiveLoopStart = Date.now();

  const contrastiveLr = CONFIG.learningRate;
  const contrastiveEpochs = CONFIG.epochs;
  let initialContrastiveLoss = 0;
  let finalContrastiveLoss = 0;
+  // Real per-epoch loss from the loop that actually updates encoder.w2 below —
+  // NOT contrastiveResult.history, which comes from contrastiveTrainer.train()
+  // above and never touches the encoder (see its own comment). Exporting that
+  // instead of this produced a flat, meaningless lossHistory in the published
+  // model's training-metrics.json.
+  const realContrastiveLossHistory = [];

  // Compute initial loss
  for (const triplet of triplets) {
@@ -1230,7 +1240,9 @@ async function main() {
      if (CONFIG.verbose) console.log(`    Epoch ${epoch + 1}/${contrastiveEpochs}: loss=${epochLoss.toFixed(6)}`);
    }
    finalContrastiveLoss = epochLoss;
+    realContrastiveLossHistory.push({ epoch: epoch + 1, loss: epochLoss });
  }
+  const realContrastiveDurationMs = Date.now() - contrastiveLoopStart;

  // Re-encode all features with updated encoder
  console.log('  Re-encoding features with updated encoder...');
@@ -1494,10 +1506,15 @@ async function main() {
  const exportModel = {
    metadata: {
      name: 'wifi-densepose-csi-embedding',
-      version: '1.0.0',
+      version: '2.0.1',
      architecture: 'csi-encoder-8-64-128',
      training: {
-        steps: contrastiveResult.history.length * contrastiveTrainer.getTripletCount(),
+        // Real epoch count and real per-epoch triplet-update count, reported
+        // separately rather than pre-multiplied into one "steps" figure --
+        // that reads as optimizer steps, but every triplet with loss>0 gets
+        // an immediate direct weight update here, not a batched gradient step.
+        epochs: realContrastiveLossHistory.length,
+        tripletUpdatesPerEpoch: triplets.length,
        loss: contrastiveResult.finalLoss,
        learningRate: CONFIG.learningRate,
      },
@@ -1609,8 +1626,14 @@ async function main() {
      initialLoss: contrastiveResult.initialLoss,
      finalLoss: contrastiveResult.finalLoss,
      improvement: contrastiveResult.improvement,
-      durationMs: contrastiveResult.durationMs,
-      lossHistory: contrastiveResult.history,
+      // Real wall-clock of the actual gradient loop -- contrastiveResult.durationMs
+      // timed the no-op baseline pass instead, same bug as lossHistory above.
+      durationMs: realContrastiveDurationMs,
+      // The real per-epoch loss from the loop that actually updates the
+      // encoder (see realContrastiveLossHistory above) -- contrastiveResult.history
+      // comes from a separate, non-weight-updating baseline pass and was flat/
+      // meaningless here.
+      lossHistory: realContrastiveLossHistory,
    },
    taskHeads: taskTrainingData.length > 0 ? {
      samples: labeledCount,
@@ -9109,9 +9109,9 @@ dependencies = [

 [[package]]
 name = "rustls"
-version = "0.23.37"
+version = "0.23.45"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "758025cb5fccfd3bc2fd74708fd4682be41d99e5dff73c377c0646c6012c73a4"
+checksum = "0d41d731c7d2f962d1ccc364cec258de3c0e93b38c2fb3ba97ac74513048d634"
 dependencies = [
 "log",
 "once_cell",
@@ -9173,9 +9173,9 @@ checksum = "f87165f0995f63a9fbeea62b64d10b4d9d8e78ec6d7d51fb2125fda7bb36788f"

 [[package]]
 name = "rustls-webpki"
-version = "0.103.13"
+version = "0.103.15"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "61c429a8649f110dddef65e2a5ad240f747e85f7758a6bccc7e5777bd33f756e"
+checksum = "f3c3cf1d8b1e7d4927e2d154c3fcb02979afb9939629c62cd9048d4f07b60ac2"
 dependencies = [
 "ring",
 "rustls-pki-types",
@@ -234,9 +234,30 @@ impl StreamingEngine {
    /// WiFi/ESP-NOW-synced multi-node deployments spuriously fail governed
    /// trust cycles even after widening the guard elsewhere.
    ///
-    /// Rebuilds the fuser, so call before any frames are processed.
+    /// Rebuilds the fuser, so call before any frames are processed. Preserves
+    /// any node positions configured via [`Self::set_node_positions`] across
+    /// the rebuild (issue #1870) — a caller that configures positions once at
+    /// startup and calls this later (e.g. after deriving a TDM schedule) must
+    /// not have that configuration silently discarded.
    pub fn set_multistatic_config(&mut self, cfg: MultistaticConfig) {
+        let positions = self.fuser.node_positions_by_id().clone();
        self.fuser = MultistaticFuser::with_config(cfg);
+        self.fuser.set_node_positions_by_id(positions);
+    }
+
+    /// Configure node positions for the governed multistatic fuser, keyed by
+    /// node id (issue #1870). Without this, `StreamingEngine`'s fuser — the
+    /// one behind `fuse_scored_calibrated`, which feeds provenance and the
+    /// witness — always fuses with every node at the origin, regardless of
+    /// deployment configuration, because nothing ever called this on it. This
+    /// is a separate `MultistaticFuser` instance from the one
+    /// `wifi-densepose-sensing-server`'s `AppState` owns (fixed for that
+    /// instance in #1860); each fuser instance needs positions set on it
+    /// independently. Safe to call before or after [`Self::set_multistatic_config`] —
+    /// order does not matter, since that method now preserves whatever
+    /// positions are already set across its rebuild.
+    pub fn set_node_positions(&mut self, positions: std::collections::HashMap<u8, [f32; 3]>) {
+        self.fuser.set_node_positions_by_id(positions);
    }

    /// Activate a per-room calibration adapter (ADR-150 §3.4). From the next
@@ -1359,4 +1380,64 @@ mod tests {
            "an extra evidence ref must not collide with a model_version that absorbs it"
        );
    }
+
+    // ---- Issue #1870: StreamingEngine's own fuser never received positions ----
+
+    /// The governed path (`fuse_scored_calibrated`, feeding provenance and the
+    /// witness) must carry each node's configured position -- not the origin
+    /// for every node, which is what happened before `set_node_positions`
+    /// existed on `StreamingEngine` and nothing ever configured this fuser
+    /// instance (distinct from the one `wifi-densepose-sensing-server`'s
+    /// `AppState` owns, fixed separately in #1860).
+    #[test]
+    fn governed_fuse_carries_each_nodes_configured_position() {
+        let (mut e, _room) = engine();
+        let mut positions = std::collections::HashMap::new();
+        positions.insert(0u8, [1.0, 2.0, 3.0]);
+        positions.insert(1u8, [4.0, 5.0, 6.0]);
+        e.set_node_positions(positions.clone());
+
+        let frames = [node_frame(0, 1000, 56), node_frame(1, 1001, 56)];
+        let (fused, _score) = e
+            .fuser
+            .fuse_scored_calibrated(&frames, &[None, None], StreamingEngine::DEFAULT_COHERENCE_ACCEPT)
+            .expect("cohort fuses");
+
+        assert_eq!(fused.node_positions.len(), frames.len());
+        for (frame, position) in fused.node_frames.iter().zip(&fused.node_positions) {
+            let expected = positions
+                .get(&frame.node_id)
+                .copied()
+                .expect("every configured node has a position in this test");
+            assert_eq!(
+                *position, expected,
+                "node {} received the wrong position on the governed path",
+                frame.node_id
+            );
+        }
+    }
+
+    /// `set_multistatic_config` used to rebuild the fuser from scratch,
+    /// silently discarding any positions configured before it. A caller that
+    /// sets positions once at startup and derives/applies a TDM-schedule
+    /// config later (a real, documented ordering per #1049/#1057) must not
+    /// lose them.
+    #[test]
+    fn positions_survive_a_later_set_multistatic_config() {
+        let (mut e, _room) = engine();
+        let mut positions = std::collections::HashMap::new();
+        positions.insert(0u8, [7.0, 8.0, 9.0]);
+        e.set_node_positions(positions.clone());
+
+        e.set_multistatic_config(MultistaticConfig {
+            guard_interval_us: 30_000,
+            ..MultistaticConfig::default()
+        });
+
+        assert_eq!(
+            e.fuser.node_position(0),
+            Some([7.0, 8.0, 9.0]),
+            "set_multistatic_config must not discard previously-configured positions"
+        );
+    }
 }
@@ -0,0 +1,69 @@
+//! Benchmarks for ADR-323 Realtek RTL8721Dx (AmebaDplus) CSI encode/decode
+//! throughput, at the real hardware's own reported dimensions (52
+//! subcarriers, 16-bit tone precision — see `example/wifi/wifi_csi/README.md`
+//! in the vendor SDK).
+
+use criterion::{black_box, criterion_group, criterion_main, Criterion};
+use wifi_densepose_hardware::realtek_csi::simulator::{RealtekCsiSimulator, SimulatorConfig};
+use wifi_densepose_hardware::realtek_csi::CsiFrame;
+
+fn bench_to_bytes_8bit(c: &mut Criterion) {
+    let mut sim = RealtekCsiSimulator::new(SimulatorConfig::default()).unwrap();
+    let frame = sim.next_frame();
+    c.bench_function("realtek_csi_to_bytes_52sc_8bit", |b| {
+        b.iter(|| black_box(frame.to_bytes().unwrap()));
+    });
+}
+
+fn bench_from_bytes_8bit(c: &mut Criterion) {
+    let mut sim = RealtekCsiSimulator::new(SimulatorConfig::default()).unwrap();
+    let wire = sim.next_frame().to_bytes().unwrap();
+    c.bench_function("realtek_csi_from_bytes_52sc_8bit", |b| {
+        b.iter(|| black_box(CsiFrame::from_bytes(black_box(&wire)).unwrap()));
+    });
+}
+
+fn bench_to_bytes_16bit(c: &mut Criterion) {
+    let cfg = SimulatorConfig {
+        num_bit_per_tone: 32,
+        ..Default::default()
+    };
+    let mut sim = RealtekCsiSimulator::new(cfg).unwrap();
+    let frame = sim.next_frame();
+    c.bench_function("realtek_csi_to_bytes_52sc_16bit", |b| {
+        b.iter(|| black_box(frame.to_bytes().unwrap()));
+    });
+}
+
+fn bench_from_bytes_16bit(c: &mut Criterion) {
+    let cfg = SimulatorConfig {
+        num_bit_per_tone: 32,
+        ..Default::default()
+    };
+    let mut sim = RealtekCsiSimulator::new(cfg).unwrap();
+    let wire = sim.next_frame().to_bytes().unwrap();
+    c.bench_function("realtek_csi_from_bytes_52sc_16bit", |b| {
+        b.iter(|| black_box(CsiFrame::from_bytes(black_box(&wire)).unwrap()));
+    });
+}
+
+fn bench_round_trip_full_datagram(c: &mut Criterion) {
+    let mut sim = RealtekCsiSimulator::new(SimulatorConfig::default()).unwrap();
+    c.bench_function("realtek_csi_round_trip_52sc_8bit", |b| {
+        b.iter(|| {
+            let frame = sim.next_frame();
+            let wire = black_box(frame.to_bytes().unwrap());
+            black_box(CsiFrame::from_bytes(&wire).unwrap());
+        });
+    });
+}
+
+criterion_group!(
+    benches,
+    bench_to_bytes_8bit,
+    bench_from_bytes_8bit,
+    bench_to_bytes_16bit,
+    bench_from_bytes_16bit,
+    bench_round_trip_full_datagram,
+);
+criterion_main!(benches);
@@ -0,0 +1,107 @@
+//! Deterministic Realtek RTL8721Dx (AmebaDplus) 1x1 CSI simulator (ADR-323).
+
+use clap::Parser;
+use std::{
+    fs::File,
+    io::{self, Write},
+    net::{SocketAddr, UdpSocket},
+    path::PathBuf,
+    thread,
+    time::Duration,
+};
+use wifi_densepose_hardware::realtek_csi::{
+    simulator::{RealtekCsiSimulator, SimulatorConfig},
+    CsiFrame, CsiMode,
+};
+
+#[derive(Debug, Parser)]
+#[command(
+    name = "realtek-csi-sim",
+    about = "Emit synthetic ADR-323 Realtek RTL8721Dx CSI frames"
+)]
+struct Args {
+    #[arg(long, default_value_t = 100)]
+    frames: u32,
+    #[arg(long, default_value = "0x5241433152544c31", value_parser=parse_u64)]
+    seed: u64,
+    #[arg(long, default_value_t = 6)]
+    channel: u8,
+    #[arg(long)]
+    bandwidth_40mhz: bool,
+    #[arg(long, default_value_t = 52)]
+    subcarriers: u16,
+    #[arg(long, default_value_t = 16)]
+    tone_bits: u8,
+    #[arg(long, default_value_t = 1)]
+    decimation: u8,
+    #[arg(long, default_value_t = 64)]
+    interval_ms: u64,
+    #[arg(long)]
+    udp: Option<SocketAddr>,
+    /// Replay: little-endian u32 length followed by one ADR-323 envelope.
+    #[arg(long)]
+    output: Option<PathBuf>,
+    #[arg(long)]
+    realtime: bool,
+}
+
+fn parse_u64(v: &str) -> Result<u64, String> {
+    if let Some(h) = v.strip_prefix("0x").or_else(|| v.strip_prefix("0X")) {
+        u64::from_str_radix(h, 16).map_err(|e| e.to_string())
+    } else {
+        v.parse()
+            .map_err(|e: std::num::ParseIntError| e.to_string())
+    }
+}
+
+fn emit(
+    frame: CsiFrame,
+    socket: Option<&UdpSocket>,
+    destination: Option<SocketAddr>,
+    output: &mut Option<File>,
+) -> Result<usize, Box<dyn std::error::Error>> {
+    let wire = frame.to_bytes()?;
+    if let (Some(s), Some(d)) = (socket, destination) {
+        if s.send_to(&wire, d)? != wire.len() {
+            return Err(io::Error::new(io::ErrorKind::WriteZero, "partial UDP datagram").into());
+        }
+    }
+    if let Some(f) = output {
+        f.write_all(&(wire.len() as u32).to_le_bytes())?;
+        f.write_all(&wire)?;
+    }
+    Ok(wire.len())
+}
+
+fn main() -> Result<(), Box<dyn std::error::Error>> {
+    let a = Args::parse();
+    if a.udp.is_none() && a.output.is_none() {
+        return Err("select at least one sink with --udp or --output".into());
+    }
+    let cfg = SimulatorConfig {
+        seed: a.seed,
+        csi_mode: CsiMode::Passive,
+        channel: a.channel,
+        bandwidth: if a.bandwidth_40mhz { 1 } else { 0 },
+        num_sub_carrier: a.subcarriers,
+        num_bit_per_tone: a.tone_bits,
+        decimation: a.decimation,
+        frame_period_us: (a.interval_ms * 1000) as u32,
+        ..Default::default()
+    };
+    let mut sim = RealtekCsiSimulator::new(cfg)?;
+    let socket = a.udp.map(|_| UdpSocket::bind("0.0.0.0:0")).transpose()?;
+    let mut output = a.output.as_ref().map(File::create).transpose()?;
+    let mut bytes = 0usize;
+    for _ in 0..a.frames {
+        bytes += emit(sim.next_frame(), socket.as_ref(), a.udp, &mut output)?;
+        if a.realtime {
+            thread::sleep(Duration::from_millis(a.interval_ms));
+        }
+    }
+    eprintln!(
+        "emitted {} synthetic Realtek RTL8721Dx CSI frames ({} bytes, channel={}, subcarriers={}, tone_bits={}, seed={:#x})",
+        a.frames, bytes, a.channel, a.subcarriers, a.tone_bits, a.seed
+    );
+    Ok(())
+}
@@ -145,13 +145,16 @@ impl PpduType {
 ///   bit 2   : STBC
 ///   bit 3   : LDPC (reserved — not yet populated by firmware)
 ///   bit 4   : 802.15.4 time-sync valid (C6 only)
-///   bit 5-7 : reserved
+///   bit 5   : ESP-IDF invalid first CSI word was zeroed by firmware
+///   bit 6-7 : reserved
 #[derive(Debug, Clone, Copy, Default, PartialEq, Eq, Serialize, Deserialize)]
 pub struct Adr018Flags {
    pub bw40: bool,
    pub stbc: bool,
    pub ldpc: bool,
    pub ieee802154_sync_valid: bool,
+    #[serde(default)]
+    pub first_word_sanitized: bool,
 }

 impl Adr018Flags {
@@ -161,6 +164,7 @@ impl Adr018Flags {
            stbc: (b & 0x04) != 0,
            ldpc: (b & 0x08) != 0,
            ieee802154_sync_valid: (b & 0x10) != 0,
+            first_word_sanitized: (b & 0x20) != 0,
        }
    }
    pub fn to_byte(self) -> u8 {
@@ -169,6 +173,7 @@ impl Adr018Flags {
        if self.stbc { b |= 0x04; }
        if self.ldpc { b |= 0x08; }
        if self.ieee802154_sync_valid { b |= 0x10; }
+        if self.first_word_sanitized { b |= 0x20; }
        b
    }
 }
@@ -413,15 +413,16 @@ mod tests {

    #[test]
    fn adr110_flags_round_trip_all_bits() {
-        // All known flag bits set: bw40 (0x01) + STBC (0x04) + LDPC (0x08) + 15.4-sync (0x10) = 0x1D
-        let data = build_test_frame_with_he(6, 1, &[(0, 0); 56], 1, 0x1D);
+        // All known flag bits set: bw40 + STBC + LDPC + sync + sanitized prefix = 0x3D.
+        let data = build_test_frame_with_he(6, 1, &[(0, 0); 56], 1, 0x3D);
        let (frame, _) = Esp32CsiParser::parse_frame(&data).unwrap();
        assert!(frame.metadata.adr018_flags.bw40);
        assert!(frame.metadata.adr018_flags.stbc);
        assert!(frame.metadata.adr018_flags.ldpc);
        assert!(frame.metadata.adr018_flags.ieee802154_sync_valid);
+        assert!(frame.metadata.adr018_flags.first_word_sanitized);
        // Round-trip the encoder
-        assert_eq!(frame.metadata.adr018_flags.to_byte(), 0x1D);
+        assert_eq!(frame.metadata.adr018_flags.to_byte(), 0x3D);
    }

    #[test]
@@ -62,6 +62,9 @@ pub mod qualcomm_csi;
 /// ADR-264 host-side framing for Realtek RTL8720F CFR and FMCW radar reports.
 /// This module has no dependency on the vendor SDK.
 pub mod rtl8720f;
+/// ADR-323 vendor-neutral Realtek RTL8721Dx (AmebaDplus) 1x1 CSI framing and
+/// simulator. This module has no dependency on the vendor SDK.
+pub mod realtek_csi;

 pub use bridge::CsiData;
 pub use csi_frame::{
@@ -0,0 +1,563 @@
+//! Vendor-neutral Realtek RTL8721Dx (AmebaDplus) 1x1 CSI transport and
+//! deterministic simulator. This is not the vendor SDK's raw
+//! `rtw_event_csi_report_info` ABI (no CRC, C flexible-array payload); see
+//! ADR-323 for the field-by-field mapping and rationale.
+
+use serde::{Deserialize, Serialize};
+use thiserror::Error;
+
+pub const RAC1_MAGIC: u32 = 0x3143_4152; // "RAC1" little endian
+pub const RAC1_VERSION: u8 = 1;
+pub const RAC1_HEADER_LEN: usize = 49;
+pub const RAC1_CRC_LEN: usize = 4;
+pub const RAC1_MAX_FRAME_LEN: usize = 65_507;
+/// Upper bound on subcarriers a 1x1 20/40 MHz OFDM/HT/VHT/HE capture can
+/// plausibly report; guards `to_bytes`/`from_bytes` against runaway sizes.
+pub const RAC1_MAX_SUBCARRIERS: usize = 4_096;
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
+#[repr(u8)]
+pub enum CsiMode {
+    Passive = 0,
+    Active = 1,
+    BoardToBoard = 2,
+}
+
+impl TryFrom<u8> for CsiMode {
+    type Error = CsiParseError;
+    fn try_from(value: u8) -> Result<Self, Self::Error> {
+        match value {
+            0 => Ok(Self::Passive),
+            1 => Ok(Self::Active),
+            2 => Ok(Self::BoardToBoard),
+            _ => Err(CsiParseError::UnknownCsiMode(value)),
+        }
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
+#[repr(u8)]
+pub enum ProtocolMode {
+    Ofdm = 0,
+    Ht = 1,
+    Vht = 2,
+    He = 3,
+}
+
+impl TryFrom<u8> for ProtocolMode {
+    type Error = CsiParseError;
+    fn try_from(value: u8) -> Result<Self, Self::Error> {
+        match value {
+            0 => Ok(Self::Ofdm),
+            1 => Ok(Self::Ht),
+            2 => Ok(Self::Vht),
+            3 => Ok(Self::He),
+            _ => Err(CsiParseError::UnknownProtocolMode(value)),
+        }
+    }
+}
+
+#[derive(Debug, Clone, Copy, Default, PartialEq, Eq, Serialize, Deserialize)]
+pub struct CsiFlags(pub u8);
+
+impl CsiFlags {
+    pub const SYNTHETIC: u8 = 1 << 0;
+    pub fn contains(self, flag: u8) -> bool {
+        self.0 & flag != 0
+    }
+}
+
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+pub struct CsiFrame {
+    /// Disambiguates multi-board illuminator/receiver deployments; 0 = unset.
+    pub node_id: u8,
+    pub csi_mode: CsiMode,
+    pub sequence: u32,
+    /// Hardware-clock microseconds; wraps roughly every 71 minutes. Consumers
+    /// must reorder by `sequence`, not raw timestamp arithmetic, across a wrap.
+    pub timestamp_us: u32,
+    pub peer_mac: [u8; 6],
+    pub trig_mac: [u8; 6],
+    pub channel: u8,
+    /// 0 = 20 MHz, 1 = 40 MHz.
+    pub bandwidth: u8,
+    pub rx_rate: u8,
+    pub protocol_mode: ProtocolMode,
+    pub num_sub_carrier: u16,
+    /// 16 (8-bit I + 8-bit Q) or 32 (16-bit I + 16-bit Q).
+    pub num_bit_per_tone: u8,
+    /// Tone group: 1/2/4/8 (every Nth tone reported).
+    pub decimation: u8,
+    /// Single RF chain (1x1 hardware).
+    pub rssi_dbm: i8,
+    pub rxsc: u8,
+    pub csi_valid: bool,
+    pub flags: CsiFlags,
+    /// One (I, Q) pair per reported subcarrier, widened to i16 regardless of
+    /// wire precision (an 8-bit wire value fits losslessly).
+    pub payload: Vec<(i16, i16)>,
+}
+
+impl CsiFrame {
+    fn component_bytes(&self) -> Result<usize, CsiParseError> {
+        match self.num_bit_per_tone {
+            16 => Ok(1),
+            32 => Ok(2),
+            other => Err(CsiParseError::InvalidToneBits(other)),
+        }
+    }
+
+    pub fn to_bytes(&self) -> Result<Vec<u8>, CsiParseError> {
+        self.validate()?;
+        let comp_bytes = self.component_bytes()?;
+        let payload_len = self
+            .payload
+            .len()
+            .checked_mul(comp_bytes * 2)
+            .ok_or(CsiParseError::LengthOverflow)?;
+        let frame_len = RAC1_HEADER_LEN
+            .checked_add(payload_len)
+            .and_then(|n| n.checked_add(RAC1_CRC_LEN))
+            .ok_or(CsiParseError::LengthOverflow)?;
+        if frame_len > RAC1_MAX_FRAME_LEN {
+            return Err(CsiParseError::FrameTooLarge(frame_len));
+        }
+        let mut out = Vec::with_capacity(frame_len);
+        out.extend_from_slice(&RAC1_MAGIC.to_le_bytes());
+        out.push(RAC1_VERSION);
+        out.extend_from_slice(&(RAC1_HEADER_LEN as u16).to_le_bytes());
+        out.extend_from_slice(&(frame_len as u32).to_le_bytes());
+        out.push(self.node_id);
+        out.push(self.csi_mode as u8);
+        out.extend_from_slice(&self.sequence.to_le_bytes());
+        out.extend_from_slice(&self.timestamp_us.to_le_bytes());
+        out.extend_from_slice(&self.peer_mac);
+        out.extend_from_slice(&self.trig_mac);
+        out.push(self.channel);
+        out.push(self.bandwidth);
+        out.push(self.rx_rate);
+        out.push(self.protocol_mode as u8);
+        out.extend_from_slice(&self.num_sub_carrier.to_le_bytes());
+        out.push(self.num_bit_per_tone);
+        out.push(self.decimation);
+        out.push(self.rssi_dbm as u8);
+        out.push(self.rxsc);
+        out.push(self.csi_valid as u8);
+        out.push(self.flags.0);
+        out.extend_from_slice(&(payload_len as u32).to_le_bytes());
+        debug_assert_eq!(out.len(), RAC1_HEADER_LEN);
+        for (i, q) in &self.payload {
+            if comp_bytes == 1 {
+                out.push(*i as i8 as u8);
+                out.push(*q as i8 as u8);
+            } else {
+                out.extend_from_slice(&i.to_le_bytes());
+                out.extend_from_slice(&q.to_le_bytes());
+            }
+        }
+        out.extend_from_slice(&crc32_ieee(&out).to_le_bytes());
+        Ok(out)
+    }
+
+    pub fn from_bytes(input: &[u8]) -> Result<(Self, usize), CsiParseError> {
+        if input.len() < RAC1_HEADER_LEN {
+            return Err(CsiParseError::InsufficientData {
+                needed: RAC1_HEADER_LEN,
+                got: input.len(),
+            });
+        }
+        let magic = u32_at(input, 0);
+        if magic != RAC1_MAGIC {
+            return Err(CsiParseError::InvalidMagic(magic));
+        }
+        if input[4] != RAC1_VERSION {
+            return Err(CsiParseError::UnsupportedVersion(input[4]));
+        }
+        let header_len = u16_at(input, 5) as usize;
+        if header_len != RAC1_HEADER_LEN {
+            return Err(CsiParseError::InvalidHeaderLength(header_len));
+        }
+        let frame_len = u32_at(input, 7) as usize;
+        if frame_len > RAC1_MAX_FRAME_LEN {
+            return Err(CsiParseError::FrameTooLarge(frame_len));
+        }
+        if frame_len < header_len + RAC1_CRC_LEN {
+            return Err(CsiParseError::InvalidFrameLength(frame_len));
+        }
+        if input.len() < frame_len {
+            return Err(CsiParseError::InsufficientData {
+                needed: frame_len,
+                got: input.len(),
+            });
+        }
+        let expected_crc = u32_at(input, frame_len - 4);
+        let actual_crc = crc32_ieee(&input[..frame_len - 4]);
+        if expected_crc != actual_crc {
+            return Err(CsiParseError::CrcMismatch {
+                expected: expected_crc,
+                actual: actual_crc,
+            });
+        }
+
+        let node_id = input[11];
+        let csi_mode = CsiMode::try_from(input[12])?;
+        let sequence = u32_at(input, 13);
+        let timestamp_us = u32_at(input, 17);
+        let mut peer_mac = [0u8; 6];
+        peer_mac.copy_from_slice(&input[21..27]);
+        let mut trig_mac = [0u8; 6];
+        trig_mac.copy_from_slice(&input[27..33]);
+        let channel = input[33];
+        let bandwidth = input[34];
+        let rx_rate = input[35];
+        let protocol_mode = ProtocolMode::try_from(input[36])?;
+        let num_sub_carrier = u16_at(input, 37);
+        let num_bit_per_tone = input[39];
+        let decimation = input[40];
+        let rssi_dbm = input[41] as i8;
+        let rxsc = input[42];
+        let csi_valid = input[43] != 0;
+        let flags = CsiFlags(input[44]);
+        let payload_len = u32_at(input, 45) as usize;
+
+        if header_len + payload_len + RAC1_CRC_LEN != frame_len {
+            return Err(CsiParseError::PayloadLengthMismatch);
+        }
+        let comp_bytes = match num_bit_per_tone {
+            16 => 1usize,
+            32 => 2usize,
+            other => return Err(CsiParseError::InvalidToneBits(other)),
+        };
+        let expected_payload_len = (num_sub_carrier as usize)
+            .checked_mul(comp_bytes * 2)
+            .ok_or(CsiParseError::LengthOverflow)?;
+        if payload_len != expected_payload_len {
+            return Err(CsiParseError::PayloadLengthMismatch);
+        }
+        let payload_bytes = &input[header_len..header_len + payload_len];
+        let payload = if comp_bytes == 1 {
+            payload_bytes
+                .chunks_exact(2)
+                .map(|b| (b[0] as i8 as i16, b[1] as i8 as i16))
+                .collect()
+        } else {
+            payload_bytes
+                .chunks_exact(4)
+                .map(|b| {
+                    (
+                        i16::from_le_bytes([b[0], b[1]]),
+                        i16::from_le_bytes([b[2], b[3]]),
+                    )
+                })
+                .collect()
+        };
+
+        let frame = Self {
+            node_id,
+            csi_mode,
+            sequence,
+            timestamp_us,
+            peer_mac,
+            trig_mac,
+            channel,
+            bandwidth,
+            rx_rate,
+            protocol_mode,
+            num_sub_carrier,
+            num_bit_per_tone,
+            decimation,
+            rssi_dbm,
+            rxsc,
+            csi_valid,
+            flags,
+            payload,
+        };
+        frame.validate()?;
+        Ok((frame, frame_len))
+    }
+
+    fn validate(&self) -> Result<(), CsiParseError> {
+        if !matches!(self.bandwidth, 0 | 1) {
+            return Err(CsiParseError::InvalidBandwidth(self.bandwidth));
+        }
+        let comp_bytes = self.component_bytes()?;
+        if self.num_sub_carrier == 0 || self.num_sub_carrier as usize > RAC1_MAX_SUBCARRIERS {
+            return Err(CsiParseError::InvalidSubcarrierCount(self.num_sub_carrier));
+        }
+        if self.payload.len() != self.num_sub_carrier as usize {
+            return Err(CsiParseError::PayloadLengthMismatch);
+        }
+        if comp_bytes == 1 {
+            let in_range = |v: i16| (i8::MIN as i16..=i8::MAX as i16).contains(&v);
+            if self.payload.iter().any(|(i, q)| !in_range(*i) || !in_range(*q)) {
+                return Err(CsiParseError::ToneValueOutOfRange);
+            }
+        }
+        Ok(())
+    }
+}
+
+#[derive(Debug, Error, PartialEq)]
+pub enum CsiParseError {
+    #[error("insufficient data: needed {needed}, got {got}")]
+    InsufficientData { needed: usize, got: usize },
+    #[error("invalid magic {0:#010x}")]
+    InvalidMagic(u32),
+    #[error("unsupported version {0}")]
+    UnsupportedVersion(u8),
+    #[error("unknown CSI mode {0}")]
+    UnknownCsiMode(u8),
+    #[error("unknown protocol mode {0}")]
+    UnknownProtocolMode(u8),
+    #[error("invalid header length {0}")]
+    InvalidHeaderLength(usize),
+    #[error("invalid frame length {0}")]
+    InvalidFrameLength(usize),
+    #[error("frame too large: {0}")]
+    FrameTooLarge(usize),
+    #[error("length arithmetic overflow")]
+    LengthOverflow,
+    #[error("payload length mismatch")]
+    PayloadLengthMismatch,
+    #[error("invalid num_bit_per_tone {0} (must be 16 or 32)")]
+    InvalidToneBits(u8),
+    #[error("invalid subcarrier count {0}")]
+    InvalidSubcarrierCount(u16),
+    #[error("invalid bandwidth code {0} (must be 0 or 1)")]
+    InvalidBandwidth(u8),
+    #[error("tone I/Q value out of range for 8-bit precision")]
+    ToneValueOutOfRange,
+    #[error("CRC mismatch: expected {expected:#010x}, actual {actual:#010x}")]
+    CrcMismatch { expected: u32, actual: u32 },
+}
+
+pub mod simulator {
+    use super::*;
+
+    #[derive(Debug, Clone)]
+    pub struct SimulatorConfig {
+        pub seed: u64,
+        pub node_id: u8,
+        pub csi_mode: CsiMode,
+        pub peer_mac: [u8; 6],
+        pub trig_mac: [u8; 6],
+        pub channel: u8,
+        pub bandwidth: u8,
+        pub rx_rate: u8,
+        pub protocol_mode: ProtocolMode,
+        pub num_sub_carrier: u16,
+        pub num_bit_per_tone: u8,
+        pub decimation: u8,
+        pub rssi_dbm: i8,
+        pub frame_period_us: u32,
+    }
+
+    impl Default for SimulatorConfig {
+        fn default() -> Self {
+            Self {
+                seed: 0x5241_4331_5254_4c31, // "RAC1RTL1"-ish
+                node_id: 1,
+                csi_mode: CsiMode::Passive,
+                peer_mac: [0xa4, 0x39, 0xb3, 0xa4, 0xbe, 0x2d],
+                trig_mac: [0x00, 0xe0, 0x4c, 0x00, 0x0a, 0xa3],
+                channel: 6,
+                bandwidth: 0,
+                rx_rate: 12, // RTW_RATE_6M
+                protocol_mode: ProtocolMode::Ofdm,
+                num_sub_carrier: 52,
+                num_bit_per_tone: 16,
+                decimation: 1,
+                rssi_dbm: -45,
+                frame_period_us: 64_000,
+            }
+        }
+    }
+
+    pub struct RealtekCsiSimulator {
+        config: SimulatorConfig,
+        rng: u64,
+        sequence: u32,
+        timestamp_us: u32,
+        motion_phase: f32,
+    }
+
+    impl RealtekCsiSimulator {
+        pub fn new(config: SimulatorConfig) -> Result<Self, CsiParseError> {
+            let s = Self {
+                rng: config.seed,
+                config,
+                sequence: 0,
+                timestamp_us: 0,
+                motion_phase: 0.0,
+            };
+            s.csi_frame().validate()?;
+            Ok(s)
+        }
+
+        pub fn next_frame(&mut self) -> CsiFrame {
+            let frame = self.csi_frame();
+            self.sequence = self.sequence.wrapping_add(1);
+            self.timestamp_us = self.timestamp_us.wrapping_add(self.config.frame_period_us);
+            self.motion_phase += 0.041;
+            frame
+        }
+
+        fn csi_frame(&self) -> CsiFrame {
+            let mut rng = self.rng ^ self.sequence as u64;
+            let comp_max = if self.config.num_bit_per_tone == 16 {
+                110.0
+            } else {
+                1800.0
+            };
+            let payload = (0..self.config.num_sub_carrier as usize)
+                .map(|tone| {
+                    rng ^= rng << 13;
+                    rng ^= rng >> 7;
+                    rng ^= rng << 17;
+                    let noise = ((rng >> 48) as i16 % 8) as f32;
+                    let phase = tone as f32 * 0.11 + self.motion_phase;
+                    (
+                        ((phase.cos() * comp_max) + noise) as i16,
+                        ((phase.sin() * comp_max) - noise) as i16,
+                    )
+                })
+                .collect();
+            CsiFrame {
+                node_id: self.config.node_id,
+                csi_mode: self.config.csi_mode,
+                sequence: self.sequence,
+                timestamp_us: self.timestamp_us,
+                peer_mac: self.config.peer_mac,
+                trig_mac: self.config.trig_mac,
+                channel: self.config.channel,
+                bandwidth: self.config.bandwidth,
+                rx_rate: self.config.rx_rate,
+                protocol_mode: self.config.protocol_mode,
+                num_sub_carrier: self.config.num_sub_carrier,
+                num_bit_per_tone: self.config.num_bit_per_tone,
+                decimation: self.config.decimation,
+                rssi_dbm: self.config.rssi_dbm,
+                rxsc: 0,
+                csi_valid: true,
+                flags: CsiFlags(CsiFlags::SYNTHETIC),
+                payload,
+            }
+        }
+    }
+}
+
+fn u16_at(b: &[u8], o: usize) -> u16 {
+    u16::from_le_bytes([b[o], b[o + 1]])
+}
+fn u32_at(b: &[u8], o: usize) -> u32 {
+    u32::from_le_bytes(b[o..o + 4].try_into().unwrap())
+}
+fn crc32_ieee(data: &[u8]) -> u32 {
+    let mut crc = 0xffff_ffffu32;
+    for &byte in data {
+        crc ^= byte as u32;
+        for _ in 0..8 {
+            crc = (crc >> 1) ^ ((0u32.wrapping_sub(crc & 1)) & 0xedb8_8320);
+        }
+    }
+    !crc
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use simulator::*;
+
+    #[test]
+    fn simulator_round_trip_is_deterministic() {
+        let cfg = SimulatorConfig::default();
+        let mut a = RealtekCsiSimulator::new(cfg.clone()).unwrap();
+        let mut b = RealtekCsiSimulator::new(cfg).unwrap();
+        let wa = a.next_frame().to_bytes().unwrap();
+        assert_eq!(wa, b.next_frame().to_bytes().unwrap());
+        let (decoded, n) = CsiFrame::from_bytes(&wa).unwrap();
+        assert_eq!(n, wa.len());
+        assert!(decoded.flags.contains(CsiFlags::SYNTHETIC));
+        assert_eq!(decoded.payload.len(), 52);
+    }
+
+    #[test]
+    fn sixteen_bit_precision_round_trip() {
+        let cfg = SimulatorConfig {
+            num_bit_per_tone: 32,
+            ..Default::default()
+        };
+        let mut sim = RealtekCsiSimulator::new(cfg).unwrap();
+        let frame = sim.next_frame();
+        let wire = frame.to_bytes().unwrap();
+        let (decoded, n) = CsiFrame::from_bytes(&wire).unwrap();
+        assert_eq!(n, wire.len());
+        assert_eq!(decoded, frame);
+    }
+
+    #[test]
+    fn crc_corruption_is_rejected() {
+        let mut s = RealtekCsiSimulator::new(SimulatorConfig::default()).unwrap();
+        let mut w = s.next_frame().to_bytes().unwrap();
+        let last = w.len() - 1;
+        w[last] ^= 1;
+        assert!(matches!(
+            CsiFrame::from_bytes(&w),
+            Err(CsiParseError::CrcMismatch { .. })
+        ));
+    }
+
+    #[test]
+    fn truncation_is_rejected() {
+        let mut s = RealtekCsiSimulator::new(SimulatorConfig::default()).unwrap();
+        let w = s.next_frame().to_bytes().unwrap();
+        assert!(matches!(
+            CsiFrame::from_bytes(&w[..w.len() - 1]),
+            Err(CsiParseError::InsufficientData { .. })
+        ));
+    }
+
+    #[test]
+    fn zero_subcarriers_is_rejected() {
+        let cfg = SimulatorConfig {
+            num_sub_carrier: 0,
+            ..Default::default()
+        };
+        assert!(matches!(
+            RealtekCsiSimulator::new(cfg),
+            Err(CsiParseError::InvalidSubcarrierCount(0))
+        ));
+    }
+
+    #[test]
+    fn invalid_tone_bits_is_rejected() {
+        let cfg = SimulatorConfig {
+            num_bit_per_tone: 24,
+            ..Default::default()
+        };
+        assert!(matches!(
+            RealtekCsiSimulator::new(cfg),
+            Err(CsiParseError::InvalidToneBits(24))
+        ));
+    }
+
+    #[test]
+    fn parser_never_panics_on_prefixes() {
+        let mut s = RealtekCsiSimulator::new(SimulatorConfig::default()).unwrap();
+        let w = s.next_frame().to_bytes().unwrap();
+        for end in 0..w.len() {
+            let _ = CsiFrame::from_bytes(&w[..end]);
+        }
+    }
+
+    #[test]
+    fn magic_mismatch_is_rejected() {
+        let mut s = RealtekCsiSimulator::new(SimulatorConfig::default()).unwrap();
+        let mut w = s.next_frame().to_bytes().unwrap();
+        w[0] ^= 0xff;
+        assert!(matches!(
+            CsiFrame::from_bytes(&w),
+            Err(CsiParseError::InvalidMagic(_))
+        ));
+    }
+}
@@ -30,7 +30,7 @@ mdns-sd = "0.11"

 # Serialization
 serde = { workspace = true }
-serde_json.workspace = true
+serde_json = { workspace = true, features = ["raw_value"] }

 # Logging
 tracing.workspace = true
@@ -43,6 +43,8 @@ per ADR-022 Phase 3.
 - **WebSocket broadcast** -- Real-time sensing updates pushed to all connected clients at
  `ws://localhost:8765/ws/sensing`.
 - **Static file serving** -- Hosts the sensing UI on port 8080 with CORS headers.
+- **Private startup baseline** -- Restores a recent, installation-bound empty-room field model
+  without storing raw CSI or authorizing numeric vital signs (ADR-355).

 ## Modules

@@ -74,6 +76,23 @@ cargo run -p wifi-densepose-sensing-server -- \
    --static-dir ./ui
 ```

+### Empty-room startup baseline
+
+Provide a stable installation ID and an application-owned private state directory:
+
+```bash
+cargo run -p wifi-densepose-sensing-server -- \
+    --installation-id installation-01 \
+    --data-dir /path/to/private/application-state
+```
+
+Complete the normal empty-room calibration, then call
+`POST /api/v1/calibration/bootstrap/promote`. The server measures a separate 12-sample holdout
+before storing an aggregate field-model snapshot. On a later start with the same installation ID,
+the snapshot is restored with `bootstrap_only` authority. It can reduce startup background false
+positives, but cannot authorize calibrated evidence or numeric heart and breathing rates. Use
+`POST /api/v1/calibration/reset` with administrator scope to remove it.
+
 ### Using as a library

 ```rust
@@ -139,6 +139,39 @@ pub fn features_from_runtime(feat: &serde_json::Value, amps: &[f64]) -> [f64; N_
    ]
 }

+/// Preserve the fifth feature's historical meaning for models trained before
+/// the server began measuring temporal frequency from a frame window.
+///
+/// Version 1 models learned a proxy equal to the strongest subcarrier index
+/// multiplied by 0.05. Version 2 and later models consume the measured
+/// temporal frequency in hertz. Keeping this translation at the model boundary
+/// prevents a server upgrade from silently changing an existing model's input
+/// distribution.
+pub fn compatible_dominant_frequency(
+    model_version: u32,
+    temporal_frequency_hz: f64,
+    amplitudes: &[f64],
+) -> f64 {
+    if model_version >= 2 {
+        return if temporal_frequency_hz.is_finite() {
+            temporal_frequency_hz.max(0.0)
+        } else {
+            0.0
+        };
+    }
+
+    amplitudes
+        .iter()
+        .enumerate()
+        .filter(|(_, amplitude)| amplitude.is_finite())
+        .max_by(|(_, left), (_, right)| {
+            left.partial_cmp(right)
+                .unwrap_or(std::cmp::Ordering::Equal)
+        })
+        .map(|(index, _)| index as f64 * 0.05)
+        .unwrap_or(0.0)
+}
+
 /// Compute statistical features from raw subcarrier amplitudes.
 fn subcarrier_stats(amps: &[f64]) -> (f64, f64, f64, f64, f64, f64, f64, f64) {
    if amps.is_empty() {
@@ -642,3 +675,21 @@ pub fn train_from_recordings(recordings_dir: &Path) -> Result<AdaptiveModel, Str
 pub fn model_path() -> PathBuf {
    PathBuf::from("data/adaptive_model.json")
 }
+
+#[cfg(test)]
+mod compatibility_tests {
+    use super::compatible_dominant_frequency;
+
+    #[test]
+    fn version_one_keeps_legacy_subcarrier_proxy() {
+        let amplitudes = [1.0, 2.0, 8.0, 3.0];
+        assert_eq!(compatible_dominant_frequency(1, 1.25, &amplitudes), 0.10);
+    }
+
+    #[test]
+    fn version_two_uses_measured_temporal_frequency() {
+        let amplitudes = [1.0, 20.0, 2.0];
+        assert_eq!(compatible_dominant_frequency(2, 1.25, &amplitudes), 1.25);
+        assert_eq!(compatible_dominant_frequency(2, f64::NAN, &amplitudes), 0.0);
+    }
+}
@@ -491,6 +491,10 @@ const READ_SAFE_MUTATIONS: &[&str] = &[
    // Capture and calibration: create data, never destroy it.
    "/api/v1/calibration/start",
    "/api/v1/calibration/stop",
+    // Promotion consumes only server measured held out evidence and stores a
+    // bounded privacy reduced prior. Cancel discards only an unfinished run.
+    "/api/v1/calibration/bootstrap/promote",
+    "/api/v1/calibration/cancel",
    "/api/v1/pose/calibrate",
    "/api/v1/recording/start",
    "/api/v1/recording/stop",
@@ -1970,6 +1974,7 @@ mod scope_gate_polarity_tests {
            (Method::DELETE, "/api/v1/models/m1"),
            (Method::DELETE, "/api/v1/recording/r1"),
            (Method::POST, "/api/v1/config/ground-truth"),
+            (Method::POST, "/api/v1/calibration/reset"),
        ] {
            assert_eq!(
                required_scope_for(&m, p),
@@ -0,0 +1,532 @@
+//! Local, privacy reduced empty room bootstrap model persistence.
+//!
+//! A bootstrap image is deliberately lower authority than a completed room
+//! calibration. It can suppress background perturbations while the server
+//! starts, but restoring it never authorizes calibrated evidence or vitals.
+
+use rand::{rngs::OsRng, RngCore};
+use serde::{Deserialize, Serialize};
+use serde_json::value::RawValue;
+use sha2::{Digest, Sha256};
+use std::fs::{self, OpenOptions};
+use std::io::{Read, Write};
+use std::path::{Path, PathBuf};
+use thiserror::Error;
+use wifi_densepose_signal::ruvsense::field_model::{
+    FieldModel, FieldModelError, FieldModelSnapshotV1,
+};
+
+pub const BOOTSTRAP_BASELINE_SCHEMA: &str = "ruview.bootstrap-empty-field-model.v2";
+pub const BOOTSTRAP_BASELINE_AUTHORITY: &str = "bootstrap_only";
+pub const BOOTSTRAP_VALIDATION_SAMPLES: usize = 12;
+pub const BOOTSTRAP_VALIDATION_MIN_EMPTY: usize = 10;
+pub const BOOTSTRAP_VALIDATION_MIN_SPACING_MS: u64 = 1_000;
+pub const BOOTSTRAP_VALIDATION_SAMPLE_TIMEOUT_MS: u64 = 4_000;
+const BOOTSTRAP_MAX_FILE_BYTES: u64 = 1_048_576;
+
+/// Exact CSI layout used to train the persisted empty room model.
+///
+/// Restoring code must require incoming frames to match this binding before
+/// the bootstrap image can influence inference.
+#[derive(Debug, Clone, Copy, Serialize, Deserialize, PartialEq, Eq)]
+#[serde(deny_unknown_fields)]
+pub struct BootstrapCsiGrid {
+    pub n_subcarriers: u16,
+    pub ppdu_type: u8,
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize, PartialEq)]
+#[serde(deny_unknown_fields)]
+struct BootstrapPayloadV2 {
+    schema: String,
+    authority: String,
+    installation_binding_sha256: String,
+    source_node_ids: Vec<u8>,
+    source_grid: BootstrapCsiGrid,
+    source_model_id: String,
+    created_at_unix_ms: u64,
+    expires_at_unix_ms: u64,
+    field_model: FieldModelSnapshotV1,
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize, PartialEq)]
+#[serde(deny_unknown_fields)]
+struct BootstrapImageV2 {
+    payload: BootstrapPayloadV2,
+    content_sha256: String,
+}
+
+#[derive(Debug, Deserialize)]
+#[serde(deny_unknown_fields)]
+struct BootstrapImageRawV2 {
+    payload: Box<RawValue>,
+    content_sha256: String,
+}
+
+#[derive(Debug, Clone, Serialize, PartialEq, Eq)]
+pub struct BootstrapBaselineMetadata {
+    pub authority: &'static str,
+    pub source_node_ids: Vec<u8>,
+    pub source_grid: BootstrapCsiGrid,
+    pub source_model_id: String,
+    pub created_at_unix_ms: u64,
+    pub expires_at_unix_ms: u64,
+    pub content_sha256: String,
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub struct BootstrapValidationSample {
+    pub fresh_tick: bool,
+    pub calibrated_empty: bool,
+    pub vital_signs_absent: bool,
+}
+
+#[derive(Debug, Clone, Copy, Serialize, PartialEq, Eq)]
+pub struct BootstrapValidationResult {
+    pub sample_count: usize,
+    pub empty_sample_count: usize,
+    pub stale_sample_count: usize,
+    pub vital_sign_sample_count: usize,
+    pub passed: bool,
+}
+
+#[derive(Debug, Error)]
+pub enum BootstrapBaselineError {
+    #[error("a stable installation_id is required for a local bootstrap baseline")]
+    MissingInstallationId,
+    #[error("bootstrap baseline path is invalid")]
+    InvalidPath,
+    #[error("bootstrap baseline file is too large")]
+    FileTooLarge,
+    #[error("bootstrap baseline image is malformed: {0}")]
+    Malformed(String),
+    #[error("bootstrap baseline belongs to another installation")]
+    InstallationMismatch,
+    #[error("bootstrap baseline has expired")]
+    Expired,
+    #[error("bootstrap baseline digest does not verify")]
+    DigestMismatch,
+    #[error("field model snapshot is invalid: {0}")]
+    FieldModel(#[from] FieldModelError),
+    #[error("bootstrap baseline storage failed: {0}")]
+    Io(#[from] std::io::Error),
+    #[error("bootstrap baseline serialization failed: {0}")]
+    Json(#[from] serde_json::Error),
+}
+
+pub fn path_in(data_dir: &Path) -> PathBuf {
+    data_dir.join("calibration").join("bootstrap-empty-v1.json")
+}
+
+pub fn installation_binding(installation_id: &str) -> Result<String, BootstrapBaselineError> {
+    let installation_id = installation_id.trim();
+    if installation_id.is_empty() || installation_id.len() > 128 {
+        return Err(BootstrapBaselineError::MissingInstallationId);
+    }
+    Ok(hex_sha256(installation_id.as_bytes()))
+}
+
+pub fn evaluate_validation(samples: &[BootstrapValidationSample]) -> BootstrapValidationResult {
+    let empty_sample_count = samples
+        .iter()
+        .filter(|sample| sample.fresh_tick && sample.calibrated_empty)
+        .count();
+    let stale_sample_count = samples.iter().filter(|sample| !sample.fresh_tick).count();
+    let vital_sign_sample_count = samples
+        .iter()
+        .filter(|sample| !sample.vital_signs_absent)
+        .count();
+    BootstrapValidationResult {
+        sample_count: samples.len(),
+        empty_sample_count,
+        stale_sample_count,
+        vital_sign_sample_count,
+        passed: samples.len() == BOOTSTRAP_VALIDATION_SAMPLES
+            && empty_sample_count >= BOOTSTRAP_VALIDATION_MIN_EMPTY
+            && stale_sample_count == 0
+            && vital_sign_sample_count == 0,
+    }
+}
+
+pub fn store(
+    path: &Path,
+    installation_id: &str,
+    source_node_ids: &[u8],
+    source_grid: BootstrapCsiGrid,
+    source_model_id: &str,
+    created_at_unix_ms: u64,
+    field_model: &FieldModel,
+) -> Result<BootstrapBaselineMetadata, BootstrapBaselineError> {
+    let snapshot = field_model.export_snapshot()?;
+    let calibrated_at_ms = snapshot.modes.calibrated_at_us / 1_000;
+    let expiry_ms = (snapshot.config.baseline_expiry_s * 1_000.0) as u64;
+    let payload = BootstrapPayloadV2 {
+        schema: BOOTSTRAP_BASELINE_SCHEMA.to_string(),
+        authority: BOOTSTRAP_BASELINE_AUTHORITY.to_string(),
+        installation_binding_sha256: installation_binding(installation_id)?,
+        source_node_ids: source_node_ids.to_vec(),
+        source_grid,
+        source_model_id: source_model_id.to_string(),
+        created_at_unix_ms,
+        expires_at_unix_ms: calibrated_at_ms.saturating_add(expiry_ms),
+        field_model: snapshot,
+    };
+    validate_payload(&payload, installation_id, created_at_unix_ms)?;
+    let content_sha256 = payload_digest(&payload)?;
+    let image = BootstrapImageV2 {
+        payload,
+        content_sha256,
+    };
+    let bytes = serde_json::to_vec(&image)?;
+    if bytes.len() as u64 > BOOTSTRAP_MAX_FILE_BYTES {
+        return Err(BootstrapBaselineError::FileTooLarge);
+    }
+    atomic_write_private(path, &bytes)?;
+    Ok(metadata(&image))
+}
+
+pub fn load(
+    path: &Path,
+    installation_id: &str,
+    current_unix_ms: u64,
+) -> Result<(FieldModel, BootstrapBaselineMetadata), BootstrapBaselineError> {
+    let file_metadata = fs::symlink_metadata(path)?;
+    if file_metadata.file_type().is_symlink() || !file_metadata.is_file() {
+        return Err(BootstrapBaselineError::InvalidPath);
+    }
+    if file_metadata.len() > BOOTSTRAP_MAX_FILE_BYTES {
+        return Err(BootstrapBaselineError::FileTooLarge);
+    }
+    let mut bytes = Vec::with_capacity(file_metadata.len() as usize);
+    OpenOptions::new()
+        .read(true)
+        .open(path)?
+        .take(BOOTSTRAP_MAX_FILE_BYTES + 1)
+        .read_to_end(&mut bytes)?;
+    if bytes.len() as u64 > BOOTSTRAP_MAX_FILE_BYTES {
+        return Err(BootstrapBaselineError::FileTooLarge);
+    }
+    // Verify the exact payload bytes written by storage before decoding the
+    // floating point model. Equivalent JSON number spellings may serialize
+    // differently, so decode and reserialize is not an integrity contract.
+    let raw_image: BootstrapImageRawV2 = serde_json::from_slice(&bytes)?;
+    if hex_sha256(raw_image.payload.get().as_bytes()) != raw_image.content_sha256 {
+        return Err(BootstrapBaselineError::DigestMismatch);
+    }
+    let payload: BootstrapPayloadV2 = serde_json::from_str(raw_image.payload.get())?;
+    validate_payload(&payload, installation_id, current_unix_ms)?;
+    let image = BootstrapImageV2 {
+        payload,
+        content_sha256: raw_image.content_sha256,
+    };
+    let model = FieldModel::from_snapshot(
+        image.payload.field_model.clone(),
+        current_unix_ms.saturating_mul(1_000),
+    )?;
+    Ok((model, metadata(&image)))
+}
+
+pub fn remove(path: &Path) -> Result<bool, BootstrapBaselineError> {
+    match fs::symlink_metadata(path) {
+        Ok(metadata) => {
+            if metadata.file_type().is_symlink() || !metadata.is_file() {
+                return Err(BootstrapBaselineError::InvalidPath);
+            }
+            fs::remove_file(path)?;
+            Ok(true)
+        }
+        Err(error) if error.kind() == std::io::ErrorKind::NotFound => Ok(false),
+        Err(error) => Err(error.into()),
+    }
+}
+
+fn validate_payload(
+    payload: &BootstrapPayloadV2,
+    installation_id: &str,
+    current_unix_ms: u64,
+) -> Result<(), BootstrapBaselineError> {
+    if payload.schema != BOOTSTRAP_BASELINE_SCHEMA
+        || payload.authority != BOOTSTRAP_BASELINE_AUTHORITY
+        || payload.source_model_id.is_empty()
+        || payload.source_model_id.len() > 128
+        || payload.source_node_ids.len() != 1
+        || !(1..=2_048).contains(&payload.source_grid.n_subcarriers)
+        || payload.source_grid.ppdu_type > 3
+        || payload.created_at_unix_ms == 0
+        || payload.expires_at_unix_ms <= payload.created_at_unix_ms
+    {
+        return Err(BootstrapBaselineError::Malformed(
+            "invalid schema, authority, identity, node set, source grid, or lifetime".into(),
+        ));
+    }
+    if payload.installation_binding_sha256 != installation_binding(installation_id)? {
+        return Err(BootstrapBaselineError::InstallationMismatch);
+    }
+    if current_unix_ms > payload.expires_at_unix_ms {
+        return Err(BootstrapBaselineError::Expired);
+    }
+    Ok(())
+}
+
+fn payload_digest(payload: &BootstrapPayloadV2) -> Result<String, serde_json::Error> {
+    Ok(hex_sha256(&serde_json::to_vec(payload)?))
+}
+
+fn metadata(image: &BootstrapImageV2) -> BootstrapBaselineMetadata {
+    BootstrapBaselineMetadata {
+        authority: BOOTSTRAP_BASELINE_AUTHORITY,
+        source_node_ids: image.payload.source_node_ids.clone(),
+        source_grid: image.payload.source_grid,
+        source_model_id: image.payload.source_model_id.clone(),
+        created_at_unix_ms: image.payload.created_at_unix_ms,
+        expires_at_unix_ms: image.payload.expires_at_unix_ms,
+        content_sha256: image.content_sha256.clone(),
+    }
+}
+
+fn hex_sha256(bytes: &[u8]) -> String {
+    let digest = Sha256::digest(bytes);
+    digest.iter().map(|byte| format!("{byte:02x}")).collect()
+}
+
+fn atomic_write_private(path: &Path, bytes: &[u8]) -> Result<(), BootstrapBaselineError> {
+    let parent = path.parent().ok_or(BootstrapBaselineError::InvalidPath)?;
+    fs::create_dir_all(parent)?;
+    let file_name = path
+        .file_name()
+        .and_then(|name| name.to_str())
+        .ok_or(BootstrapBaselineError::InvalidPath)?;
+    let mut nonce = [0_u8; 8];
+    OsRng.fill_bytes(&mut nonce);
+    let temporary = parent.join(format!(
+        ".{file_name}.{:016x}.tmp",
+        u64::from_le_bytes(nonce)
+    ));
+
+    let mut options = OpenOptions::new();
+    options.write(true).create_new(true);
+    #[cfg(unix)]
+    {
+        use std::os::unix::fs::OpenOptionsExt;
+        options.mode(0o600);
+    }
+    let write_result = (|| -> Result<(), std::io::Error> {
+        let mut file = options.open(&temporary)?;
+        file.write_all(bytes)?;
+        file.sync_all()?;
+        fs::rename(&temporary, path)?;
+        Ok(())
+    })();
+    if write_result.is_err() {
+        let _ = fs::remove_file(&temporary);
+    }
+    write_result.map_err(Into::into)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use wifi_densepose_signal::ruvsense::field_model::FieldModelConfig;
+
+    const TEST_GRID: BootstrapCsiGrid = BootstrapCsiGrid {
+        n_subcarriers: 192,
+        ppdu_type: 2,
+    };
+
+    fn completed_model(now_us: u64) -> FieldModel {
+        let mut model = FieldModel::new(FieldModelConfig {
+            n_links: 1,
+            n_subcarriers: 4,
+            n_modes: 2,
+            min_calibration_frames: 3,
+            min_calibration_duration_s: 0.0,
+            baseline_expiry_s: 3_600.0,
+        })
+        .unwrap();
+        for index in 0..3 {
+            model
+                .feed_calibration(&[vec![1.0 + index as f64, 2.0, 3.0, 4.0]])
+                .unwrap();
+        }
+        model.finalize_calibration(now_us, 7).unwrap();
+        model
+    }
+
+    #[test]
+    fn round_trip_is_installation_bound_and_contains_no_raw_frames() {
+        let dir = tempfile::tempdir().unwrap();
+        let path = path_in(dir.path());
+        let now_ms = 1_000_000;
+        let model = completed_model(now_ms * 1_000);
+        let stored = store(&path, "home-a", &[5], TEST_GRID, "model", now_ms, &model).unwrap();
+        let text = String::from_utf8(fs::read(&path).unwrap()).unwrap();
+        assert!(!text.contains("home-a"));
+        assert!(!text.contains("raw_csi"));
+        assert_eq!(stored.source_grid, TEST_GRID);
+
+        let (restored, loaded) = load(&path, "home-a", now_ms + 1).unwrap();
+        assert_eq!(stored, loaded);
+        assert_eq!(
+            restored.export_snapshot().unwrap(),
+            model.export_snapshot().unwrap()
+        );
+        assert!(matches!(
+            load(&path, "home-b", now_ms + 1),
+            Err(BootstrapBaselineError::InstallationMismatch)
+        ));
+    }
+
+    #[test]
+    fn tamper_and_expiry_fail_closed() {
+        let dir = tempfile::tempdir().unwrap();
+        let path = path_in(dir.path());
+        let now_ms = 1_000_000;
+        let model = completed_model(now_ms * 1_000);
+        store(&path, "home-a", &[5], TEST_GRID, "model", now_ms, &model).unwrap();
+
+        let mut image: serde_json::Value =
+            serde_json::from_slice(&fs::read(&path).unwrap()).unwrap();
+        image["payload"]["source_grid"]["n_subcarriers"] = serde_json::json!(64);
+        fs::write(&path, serde_json::to_vec(&image).unwrap()).unwrap();
+        assert!(matches!(
+            load(&path, "home-a", now_ms + 1),
+            Err(BootstrapBaselineError::DigestMismatch)
+        ));
+
+        store(&path, "home-a", &[5], TEST_GRID, "model", now_ms, &model).unwrap();
+        assert!(matches!(
+            load(&path, "home-a", now_ms + 3_600_001),
+            Err(BootstrapBaselineError::Expired)
+                | Err(BootstrapBaselineError::FieldModel(
+                    FieldModelError::BaselineExpired { .. }
+                ))
+        ));
+    }
+
+    #[test]
+    fn store_rejects_invalid_source_grid() {
+        let dir = tempfile::tempdir().unwrap();
+        let path = path_in(dir.path());
+        let now_ms = 1_000_000;
+        let model = completed_model(now_ms * 1_000);
+
+        for source_grid in [
+            BootstrapCsiGrid {
+                n_subcarriers: 0,
+                ppdu_type: 0,
+            },
+            BootstrapCsiGrid {
+                n_subcarriers: 2_049,
+                ppdu_type: 0,
+            },
+            BootstrapCsiGrid {
+                n_subcarriers: 192,
+                ppdu_type: 4,
+            },
+        ] {
+            assert!(matches!(
+                store(&path, "home-a", &[5], source_grid, "model", now_ms, &model,),
+                Err(BootstrapBaselineError::Malformed(_))
+            ));
+        }
+    }
+
+    #[test]
+    fn store_requires_exactly_one_source_node() {
+        let dir = tempfile::tempdir().unwrap();
+        let path = path_in(dir.path());
+        let now_ms = 1_000_000;
+        let model = completed_model(now_ms * 1_000);
+
+        for source_node_ids in [&[][..], &[5, 7][..]] {
+            assert!(matches!(
+                store(
+                    &path,
+                    "home-a",
+                    source_node_ids,
+                    TEST_GRID,
+                    "model",
+                    now_ms,
+                    &model,
+                ),
+                Err(BootstrapBaselineError::Malformed(_))
+            ));
+        }
+    }
+
+    #[test]
+    fn source_grid_is_required_when_loading_a_v2_image() {
+        let dir = tempfile::tempdir().unwrap();
+        let path = path_in(dir.path());
+        let now_ms = 1_000_000;
+        let model = completed_model(now_ms * 1_000);
+        store(&path, "home-a", &[5], TEST_GRID, "model", now_ms, &model).unwrap();
+
+        let mut image: serde_json::Value =
+            serde_json::from_slice(&fs::read(&path).unwrap()).unwrap();
+        image["payload"]
+            .as_object_mut()
+            .unwrap()
+            .remove("source_grid");
+        let payload = serde_json::to_vec(&image["payload"]).unwrap();
+        let rewritten = format!(
+            "{{\"payload\":{},\"content_sha256\":\"{}\"}}",
+            String::from_utf8(payload.clone()).unwrap(),
+            hex_sha256(&payload)
+        );
+        fs::write(&path, rewritten).unwrap();
+
+        assert!(matches!(
+            load(&path, "home-a", now_ms + 1),
+            Err(BootstrapBaselineError::Json(_))
+        ));
+    }
+
+    #[test]
+    fn promotion_gate_requires_twelve_fresh_samples_and_zero_vitals() {
+        assert_eq!(BOOTSTRAP_VALIDATION_MIN_SPACING_MS, 1_000);
+        assert_eq!(BOOTSTRAP_VALIDATION_SAMPLE_TIMEOUT_MS, 4_000);
+        assert!(BOOTSTRAP_VALIDATION_SAMPLE_TIMEOUT_MS >= BOOTSTRAP_VALIDATION_MIN_SPACING_MS);
+        let passing = vec![
+            BootstrapValidationSample {
+                fresh_tick: true,
+                calibrated_empty: true,
+                vital_signs_absent: true,
+            };
+            BOOTSTRAP_VALIDATION_SAMPLES
+        ];
+        assert!(evaluate_validation(&passing).passed);
+
+        let mut stale = passing.clone();
+        stale[0].fresh_tick = false;
+        assert!(!evaluate_validation(&stale).passed);
+        let mut vital = passing;
+        vital[0].vital_signs_absent = false;
+        assert!(!evaluate_validation(&vital).passed);
+    }
+
+    #[test]
+    fn restart_verifies_the_exact_stored_payload_bytes() {
+        let dir = tempfile::tempdir().unwrap();
+        let path = path_in(dir.path());
+        let now_ms = 1_000_000;
+        let model = completed_model(now_ms * 1_000);
+        store(&path, "home-a", &[5], TEST_GRID, "model", now_ms, &model).unwrap();
+
+        let original = fs::read_to_string(&path).unwrap();
+        let image: BootstrapImageRawV2 = serde_json::from_str(&original).unwrap();
+        let rewritten_payload = image.payload.get().replacen(
+            "\"min_calibration_duration_s\":0.0",
+            "\"min_calibration_duration_s\":0.00",
+            1,
+        );
+        assert_ne!(rewritten_payload, image.payload.get());
+        let digest = hex_sha256(rewritten_payload.as_bytes());
+        let rewritten =
+            format!("{{\"payload\":{rewritten_payload},\"content_sha256\":\"{digest}\"}}");
+        fs::write(&path, rewritten).unwrap();
+
+        let (_, loaded) = load(&path, "home-a", now_ms + 1).unwrap();
+        assert_eq!(loaded.content_sha256, digest);
+    }
+}
@@ -178,7 +178,12 @@ pub struct Args {
    #[arg(long, value_name = "TYPE")]
    pub build_index: Option<String>,

-    /// Node positions for multistatic fusion (format: "x,y,z;x,y,z;...")
+    /// Node positions for multistatic fusion.
+    ///
+    /// Two forms, mixable: "x,y,z;..." positional, where each entry's identity
+    /// is its index, and "node_id:x,y,z;..." explicit. Prefer the explicit form
+    /// unless the fleet is numbered 0,1,2,... — otherwise "the third entry" and
+    /// "node 3" are different nodes and nothing in the string says which is meant.
    #[arg(long, env = "SENSING_NODE_POSITIONS")]
    pub node_positions: Option<String>,

@@ -11,6 +11,141 @@ use crate::vital_signs::VitalSigns;

 const EDGE_MAX_PERSONS: u8 = 4;

+/// Estimate a real temporal motion frequency from recent CSI amplitude
+/// history. Each frame is reduced to its mean amplitude, detrended, Hann
+/// windowed, and evaluated on exact DFT bins.
+pub fn estimate_temporal_dominant_frequency_hz(
+    frame_history: &VecDeque<Vec<f64>>,
+    sample_rate_hz: f64,
+) -> f64 {
+    if !sample_rate_hz.is_finite() || sample_rate_hz <= 0.0 {
+        return 0.0;
+    }
+
+    let recent_frames: Vec<&Vec<f64>> = frame_history
+        .iter()
+        .rev()
+        .take(128)
+        .collect();
+    if recent_frames
+        .iter()
+        .any(|frame| frame.is_empty() || frame.iter().any(|value| !value.is_finite()))
+    {
+        return 0.0;
+    }
+    let samples: Vec<f64> = recent_frames
+        .into_iter()
+        .rev()
+        .map(|frame| frame.iter().sum::<f64>() / frame.len() as f64)
+        .collect();
+    let n = samples.len();
+    if n < 16 {
+        return 0.0;
+    }
+
+    let mean = samples.iter().sum::<f64>() / n as f64;
+    let upper_hz = 4.0_f64.min(sample_rate_hz * 0.45);
+    if upper_hz < 0.1 {
+        return 0.0;
+    }
+
+    let mut powers = Vec::new();
+    for bin in 1..=(n / 2) {
+        let frequency_hz = bin as f64 * sample_rate_hz / n as f64;
+        if !(0.1..=upper_hz).contains(&frequency_hz) {
+            continue;
+        }
+        let mut real = 0.0;
+        let mut imag = 0.0;
+        let angle_step = 2.0 * std::f64::consts::PI * bin as f64 / n as f64;
+        let (step_sin, step_cos) = angle_step.sin_cos();
+        let mut angle_cos = 1.0;
+        let mut angle_sin = 0.0;
+        for (index, sample) in samples.iter().enumerate() {
+            let window =
+                0.5 * (1.0 - (2.0 * std::f64::consts::PI * index as f64 / (n - 1) as f64).cos());
+            let value = (sample - mean) * window;
+            real += value * angle_cos;
+            imag -= value * angle_sin;
+            let next_cos = angle_cos * step_cos - angle_sin * step_sin;
+            angle_sin = angle_sin * step_cos + angle_cos * step_sin;
+            angle_cos = next_cos;
+        }
+        powers.push((frequency_hz, real * real + imag * imag));
+    }
+    if powers.is_empty() {
+        return 0.0;
+    }
+    let mean_power = powers.iter().map(|(_, power)| power).sum::<f64>() / powers.len() as f64;
+    let (peak_hz, peak_power) = powers
+        .into_iter()
+        .max_by(|left, right| {
+            left.1
+                .partial_cmp(&right.1)
+                .unwrap_or(std::cmp::Ordering::Equal)
+        })
+        .unwrap_or((0.0, 0.0));
+    if mean_power <= f64::EPSILON || peak_power / mean_power < 2.0 {
+        0.0
+    } else {
+        peak_hz
+    }
+}
+
+#[cfg(test)]
+mod temporal_frequency_tests {
+    use super::*;
+
+    #[test]
+    fn recovers_temporal_frequency_in_hertz() {
+        let sample_rate_hz = 20.0;
+        let target_hz = 1.2;
+        let mut history = VecDeque::new();
+        for sample in 0..100 {
+            let t = sample as f64 / sample_rate_hz;
+            let value = 20.0 + 2.0 * (2.0 * std::f64::consts::PI * target_hz * t).sin();
+            history.push_back(vec![value; 56]);
+        }
+        let measured = estimate_temporal_dominant_frequency_hz(&history, sample_rate_hz);
+        assert!((measured - target_hz).abs() <= 0.21, "measured {measured} Hz");
+    }
+
+    #[test]
+    fn abstains_on_short_or_flat_history() {
+        let short = VecDeque::from(vec![vec![20.0; 56]; 15]);
+        assert_eq!(estimate_temporal_dominant_frequency_hz(&short, 20.0), 0.0);
+        let flat = VecDeque::from(vec![vec![20.0; 56]; 100]);
+        assert_eq!(estimate_temporal_dominant_frequency_hz(&flat, 20.0), 0.0);
+        let mut corrupt = flat;
+        corrupt[50][4] = f64::NAN;
+        assert_eq!(estimate_temporal_dominant_frequency_hz(&corrupt, 20.0), 0.0);
+    }
+
+    #[test]
+    fn temporal_frequency_p95_stays_below_server_budget() {
+        let sample_rate_hz = 50.0;
+        let mut history = VecDeque::new();
+        for sample in 0..128 {
+            let t = sample as f64 / sample_rate_hz;
+            let value = 20.0 + 2.0 * (2.0 * std::f64::consts::PI * 1.2 * t).sin();
+            history.push_back(vec![value; 256]);
+        }
+        let mut timings = Vec::with_capacity(1_000);
+        for _ in 0..1_000 {
+            let start = std::time::Instant::now();
+            std::hint::black_box(estimate_temporal_dominant_frequency_hz(
+                std::hint::black_box(&history),
+                sample_rate_hz,
+            ));
+            timings.push(start.elapsed());
+        }
+        timings.sort_unstable();
+        let p95 = timings[949];
+        eprintln!("temporal dominant frequency p95: {p95:?}");
+        assert!(p95 < std::time::Duration::from_millis(10), "p95 {p95:?}");
+    }
+}
+
 /// Person count is supporting evidence, never an independent occupancy claim.
 /// Return zero and mark invalid for contradictory or out-of-range firmware.
 fn sanitize_edge_person_count(presence: bool, raw: u8) -> (u8, bool) {
@@ -469,14 +604,7 @@ pub fn extract_features_from_frame(
        0.0
    };

-    let peak_idx = frame
-        .amplitudes
-        .iter()
-        .enumerate()
-        .max_by(|a, b| a.1.partial_cmp(b.1).unwrap_or(std::cmp::Ordering::Equal))
-        .map(|(i, _)| i)
-        .unwrap_or(0);
-    let dominant_freq_hz = peak_idx as f64 * 0.05;
+    let dominant_freq_hz = estimate_temporal_dominant_frequency_hz(frame_history, sample_rate_hz);

    let threshold = mean_amp * 1.2;
    let change_points = frame
@@ -485,7 +613,9 @@ pub fn extract_features_from_frame(
        .filter(|w| (w[0] < threshold) != (w[1] < threshold))
        .count();

-    let temporal_motion_score = if let Some(prev_frame) = frame_history.back() {
+    // The caller appends the current frame before extraction, so the true
+    // predecessor is the second item from the back.
+    let temporal_motion_score = if let Some(prev_frame) = frame_history.iter().rev().nth(1) {
        let n_cmp = n_sub.min(prev_frame.len());
        if n_cmp > 0 {
            let diff_energy: f64 = (0..n_cmp)
@@ -636,13 +766,18 @@ pub fn adaptive_override(
            .back()
            .map(|v| v.as_slice())
            .unwrap_or(&[]);
+        let dominant_frequency = adaptive_classifier::compatible_dominant_frequency(
+            model.version,
+            features.dominant_freq_hz,
+            amps,
+        );
        let feat_arr = adaptive_classifier::features_from_runtime(
            &serde_json::json!({
                "variance": features.variance,
                "motion_band_power": features.motion_band_power,
                "breathing_band_power": features.breathing_band_power,
                "spectral_power": features.spectral_power,
-                "dominant_freq_hz": features.dominant_freq_hz,
+                "dominant_freq_hz": dominant_frequency,
                "change_points": features.change_points,
                "mean_rssi": features.mean_rssi,
            }),
@@ -15,6 +15,15 @@ use wifi_densepose_signal::ruvsense::field_model::{

 use super::score_to_person_count;

+/// Versioned schema for the immutable receipt emitted after field-model calibration.
+pub const CALIBRATION_MODEL_RECEIPT_SCHEMA: &str =
+    "ruview.calibration.field-model-receipt.v1";
+
+/// Versioned schema for per-frame calibrated occupancy evidence bound to a
+/// model receipt, published on the sensing stream.
+pub const CALIBRATED_PRESENCE_EVIDENCE_SCHEMA: &str =
+    "ruview.calibration.calibrated-presence-evidence.v2";
+
 /// Length-only canonicalizer for calibration frames (issue #1170 pattern,
 /// shared with `multistatic_bridge`). Raw ESP32 amplitudes arrive at the
 /// hardware's native width (HT20 ≈ 64, HT40 ≈ 128/192); the FieldModel is
@@ -40,6 +49,106 @@ const ENERGY_THRESH_3: f64 = 25.0;
 /// reliable — genuine higher counts come from the multistatic fusion path.
 const MAX_SINGLE_LINK_OCCUPANCY: usize = 3;

+/// Low-authority comparison of the current source window with a restored
+/// empty-room bootstrap image. This is background conformance only and cannot
+/// authorize presence, person count, pose, identity, or vital signs.
+#[derive(Debug, Clone, Copy, PartialEq)]
+pub struct BootstrapBackgroundMatch {
+    pub matches_empty: bool,
+    pub score: Option<f64>,
+    pub normalized_residual_z: Option<f64>,
+    pub maturity: f64,
+    pub reliable: bool,
+    pub residual_energy: f64,
+    pub residual_energy_threshold: f64,
+    pub window_size: usize,
+    pub reference_window_count: usize,
+}
+
+fn mean_frame(frames: &[Vec<f64>]) -> Option<Vec<f64>> {
+    let width = frames.first()?.len();
+    if width == 0 {
+        return None;
+    }
+    let mut mean = vec![0.0_f64; width];
+    let mut count = 0_usize;
+    for frame in frames {
+        if frame.len() != width {
+            continue;
+        }
+        for (sum, value) in mean.iter_mut().zip(frame.iter()) {
+            *sum += value;
+        }
+        count += 1;
+    }
+    if count == 0 {
+        return None;
+    }
+    for value in &mut mean {
+        *value /= count as f64;
+    }
+    Some(mean)
+}
+
+fn perturbation_occupancy(field: &FieldModel, frames: &[Vec<f64>]) -> Option<usize> {
+    let adaptive_threshold = field.empty_room_residual_energy_threshold();
+    let frame = match adaptive_threshold {
+        Some(_) => mean_frame(frames)?,
+        None => frames.first()?.clone(),
+    };
+    let perturbation = field.extract_perturbation(&[frame]).ok()?;
+    let count = match adaptive_threshold {
+        Some(threshold) => {
+            let empty_threshold = threshold.max(1.0);
+            if perturbation.total_energy > empty_threshold * 25.0 {
+                3
+            } else if perturbation.total_energy > empty_threshold * 12.0 {
+                2
+            } else if perturbation.total_energy > empty_threshold {
+                1
+            } else {
+                0
+            }
+        }
+        None => {
+            if perturbation.total_energy > ENERGY_THRESH_3 {
+                3
+            } else if perturbation.total_energy > ENERGY_THRESH_2 {
+                2
+            } else if perturbation.total_energy > 1.0 {
+                1
+            } else {
+                0
+            }
+        }
+    };
+    Some(count)
+}
+
+/// Provenance for a count produced by the calibrated field model. Callers
+/// that attach calibration evidence must never substitute the score heuristic
+/// when the calibrated path cannot evaluate the observation.
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum CalibratedOccupancyMethod {
+    Eigenvalue,
+    PerturbationEnergy,
+}
+
+impl CalibratedOccupancyMethod {
+    pub const fn wire_name(self) -> &'static str {
+        match self {
+            Self::Eigenvalue => "field_model_eigenvalue_v1",
+            Self::PerturbationEnergy => "field_model_perturbation_energy_v1",
+        }
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub struct CalibratedOccupancy {
+    pub person_count: usize,
+    pub method: CalibratedOccupancyMethod,
+}
+
 /// Create a FieldModelConfig for single-link mode (one ESP32 node = one link).
 /// This avoids the DimensionMismatch error when feeding single-frame observations.
 pub fn single_link_config() -> FieldModelConfig {
@@ -49,6 +158,18 @@ pub fn single_link_config() -> FieldModelConfig {
    }
 }

+/// Resolve the model status at the observation wall clock. `FieldModel::status`
+/// records the state at collection or restore time and does not advance as a
+/// long-running server crosses the stale and expiry boundaries.
+pub fn calibration_status_at(field: &FieldModel, observed_at_us: u64) -> CalibrationStatus {
+    match field.status() {
+        CalibrationStatus::Uncalibrated | CalibrationStatus::Collecting => field.status(),
+        CalibrationStatus::Fresh | CalibrationStatus::Stale | CalibrationStatus::Expired => {
+            field.check_freshness(observed_at_us)
+        }
+    }
+}
+
 /// Estimate occupancy using the FieldModel when calibrated, falling back
 /// to the score-based heuristic otherwise.
 ///
@@ -58,16 +179,17 @@ pub fn single_link_config() -> FieldModelConfig {
 pub fn occupancy_or_fallback(
    field: &FieldModel,
    frame_history: &VecDeque<Vec<f64>>,
+    observed_at_us: u64,
    smoothed_score: f64,
    prev_count: usize,
 ) -> usize {
-    match field.status() {
+    match calibration_status_at(field, observed_at_us) {
        CalibrationStatus::Fresh | CalibrationStatus::Stale => {
            let frames: Vec<Vec<f64>> = frame_history
                .iter()
                .rev()
                .take(OCCUPANCY_WINDOW)
-                .cloned()
+                .map(|frame| CALIB_NORMALIZER.resample_to_canonical(frame))
                .collect();

            if frames.is_empty() {
@@ -87,82 +209,197 @@ pub fn occupancy_or_fallback(

            // Fallback: perturbation energy thresholds.
            // FieldModel expects [n_links][n_subcarriers] — we use n_links=1.
-            let observation = vec![frames[0].clone()];
-            match field.extract_perturbation(&observation) {
-                Ok(perturbation) => {
-                    if perturbation.total_energy > ENERGY_THRESH_3 {
-                        3
-                    } else if perturbation.total_energy > ENERGY_THRESH_2 {
-                        2
-                    } else if perturbation.total_energy > 1.0 {
-                        1
-                    } else {
-                        0
-                    }
-                }
-                Err(_) => score_to_person_count(smoothed_score, prev_count),
-            }
+            perturbation_occupancy(field, &frames)
+                .unwrap_or_else(|| score_to_person_count(smoothed_score, prev_count))
        }
        _ => score_to_person_count(smoothed_score, prev_count),
    }
 }

-/// Feed the latest frame to the FieldModel during calibration collection.
+/// Return true only when a restored low-authority bootstrap model has a full
+/// runtime window and that model resolves the window as empty. This helper is
+/// deliberately one-way: a bootstrap prior may suppress an obvious background
+/// false positive, but cannot authorize presence or vital signs.
+pub fn bootstrap_empty_prior_applies(
+    field: &FieldModel,
+    frame_history: &VecDeque<Vec<f64>>,
+    observed_at_us: u64,
+) -> bool {
+    bootstrap_background_match(field, frame_history, observed_at_us)
+        .is_some_and(|result| result.matches_empty)
+}
+
+/// Score the current canonical runtime window against the learned empty-room
+/// residual references. Legacy models without scalar references preserve the
+/// binary match but intentionally return no score.
+pub fn bootstrap_background_match(
+    field: &FieldModel,
+    frame_history: &VecDeque<Vec<f64>>,
+    observed_at_us: u64,
+) -> Option<BootstrapBackgroundMatch> {
+    if frame_history.len() < OCCUPANCY_WINDOW
+        || field.check_freshness(observed_at_us) != CalibrationStatus::Fresh
+    {
+        return None;
+    }
+    let frames: Vec<Vec<f64>> = frame_history
+        .iter()
+        .rev()
+        .take(OCCUPANCY_WINDOW)
+        .map(|frame| CALIB_NORMALIZER.resample_to_canonical(frame))
+        .collect();
+    let result = field.empty_room_match(&frames)?;
+    Some(BootstrapBackgroundMatch {
+        matches_empty: result.matches_empty,
+        score: result.score,
+        normalized_residual_z: result.normalized_residual_z,
+        maturity: result.maturity,
+        reliable: result.reliable,
+        residual_energy: result.residual_energy,
+        residual_energy_threshold: result.residual_energy_threshold,
+        window_size: result.window_size,
+        reference_window_count: result.reference_window_count,
+    })
+}
+
+/// Produce a fail-closed occupancy result from a fresh calibrated model.
+pub fn calibrated_occupancy(
+    field: &FieldModel,
+    frame_history: &VecDeque<Vec<f64>>,
+    observed_at_us: u64,
+) -> Option<CalibratedOccupancy> {
+    if field.check_freshness(observed_at_us) != CalibrationStatus::Fresh {
+        return None;
+    }
+    let frames: Vec<Vec<f64>> = frame_history
+        .iter()
+        .rev()
+        .take(OCCUPANCY_WINDOW)
+        .map(|frame| CALIB_NORMALIZER.resample_to_canonical(frame))
+        .collect();
+    if frames.is_empty() {
+        return None;
+    }
+    if let Ok(person_count) = field.estimate_occupancy(&frames) {
+        return Some(CalibratedOccupancy {
+            person_count: person_count.min(MAX_SINGLE_LINK_OCCUPANCY),
+            method: CalibratedOccupancyMethod::Eigenvalue,
+        });
+    }
+    Some(CalibratedOccupancy {
+        person_count: perturbation_occupancy(field, &frames)?,
+        method: CalibratedOccupancyMethod::PerturbationEnergy,
+    })
+}
+
+/// Feed the current CSI frame to the FieldModel during calibration.
 ///
 /// Acts while the model is `Uncalibrated` or `Collecting`. The first fed frame
 /// flips a freshly-started (`Uncalibrated`) model to `Collecting` inside
 /// `feed_calibration`; without accepting the `Uncalibrated` state here the two
 /// gates deadlock and the frame count never leaves 0 (calibration/start yields
-/// an `Uncalibrated` model that nothing would ever advance). Wraps the latest
-/// frame as a single-link observation (n_links=1) and feeds it.
-pub fn maybe_feed_calibration(field: &mut FieldModel, frame_history: &VecDeque<Vec<f64>>) {
+/// an `Uncalibrated` model that nothing would ever advance). Edge-vitals
+/// packets have no CSI observation and must never call this helper. The caller
+/// owns the stateful sequence admission gate. Wraps the current frame as a
+/// single-link observation (n_links=1) and feeds it.
+pub fn maybe_feed_calibration(field: &mut FieldModel, amplitudes: &[f64]) -> bool {
    if !matches!(
        field.status(),
        CalibrationStatus::Uncalibrated | CalibrationStatus::Collecting
-    ) {
-        return;
+    ) || amplitudes.is_empty()
+    {
+        return false;
    }
-    if let Some(latest) = frame_history.back() {
-        // Resample the raw amplitude vector onto the FieldModel's canonical
-        // 56-tone grid before feeding. Real HT40 nodes stream 128-wide frames;
-        // feeding those raw made every `feed_calibration` fail DimensionMismatch
-        // (swallowed at debug level), pinning frame_count at 0 even after the
-        // status-gate deadlock was fixed. Single-link observation: [1][56].
-        let canonical = CALIB_NORMALIZER.resample_to_canonical(latest);
-        let observations = vec![canonical];
-        if let Err(e) = field.feed_calibration(&observations) {
+    // Resample the raw amplitude vector onto the FieldModel's canonical
+    // 56-tone grid before feeding. Real HT40 nodes stream 128-wide frames;
+    // feeding those raw made every `feed_calibration` fail DimensionMismatch
+    // (swallowed at debug level), pinning frame_count at 0 even after the
+    // status-gate deadlock was fixed. Single-link observation: [1][56].
+    let canonical = CALIB_NORMALIZER.resample_to_canonical(amplitudes);
+    let observations = vec![canonical];
+    match field.feed_calibration(&observations) {
+        Ok(()) => true,
+        Err(e) => {
            tracing::debug!("FieldModel calibration feed: {e}");
+            false
        }
    }
 }

-/// Parse node positions from a semicolon-delimited string.
+/// One parsed `--node-positions` entry: a position, and the node id if the
+/// operator named one explicitly.
 ///
-/// Format: `"x,y,z;x,y,z;..."` where each coordinate is an `f32`.
-/// Malformed entries are skipped with a warning log.
-pub fn parse_node_positions(input: &str) -> Vec<[f32; 3]> {
+/// `node_id: None` means the entry was given positionally, so its identity is
+/// its index in the list — which is only the same thing as a node id on a fleet
+/// numbered `0, 1, 2, ...`.
+#[derive(Debug, Clone, Copy, PartialEq)]
+pub struct NodePositionEntry {
+    pub node_id: Option<u8>,
+    pub position: [f32; 3],
+}
+
+/// Parse node positions, keeping any explicit node ids.
+///
+/// Two accepted forms, per entry:
+///
+/// * `x,y,z`           — positional; identity is the entry's index.
+/// * `node_id:x,y,z`   — explicit; identity is the stated node id.
+///
+/// The explicit form exists because the positional one is only unambiguous on a
+/// fleet whose ids happen to run `0, 1, 2, ...`. Anywhere else, "the third
+/// entry" and "node 3" are different nodes, and nothing in the string says
+/// which was meant. Naming the id removes the guess rather than relocating it.
+///
+/// Both forms may be mixed; a positional entry keeps its index as its identity.
+/// Malformed entries are skipped with a warning rather than failing the boot —
+/// a typo in one triplet should not take the server down.
+pub fn parse_node_position_entries(input: &str) -> Vec<NodePositionEntry> {
    if input.is_empty() {
        return Vec::new();
    }
    input
        .split(';')
        .enumerate()
-        .filter_map(|(idx, triplet)| {
+        .filter_map(|(idx, raw)| {
+            let entry = raw.trim();
+            if entry.is_empty() {
+                return None;
+            }
+            // An explicit id is everything before the first ':'. Coordinates
+            // never contain one, so this cannot be ambiguous.
+            let (node_id, triplet) = match entry.split_once(':') {
+                Some((id_str, rest)) => match id_str.trim().parse::<u8>() {
+                    Ok(id) => (Some(id), rest),
+                    Err(_) => {
+                        tracing::warn!(
+                            "Skipping node position entry {idx}: '{entry}' has \
+                             an unparseable node id before ':' (expected \
+                             node_id:x,y,z with node_id in 0..=255)"
+                        );
+                        return None;
+                    }
+                },
+                None => (None, entry),
+            };
+
            let parts: Vec<&str> = triplet.split(',').collect();
            if parts.len() != 3 {
                tracing::warn!(
-                    "Skipping malformed node position entry {idx}: '{triplet}' (expected x,y,z)"
+                    "Skipping malformed node position entry {idx}: '{entry}' (expected x,y,z)"
                );
                return None;
            }
            match (
-                parts[0].parse::<f32>(),
-                parts[1].parse::<f32>(),
-                parts[2].parse::<f32>(),
+                parts[0].trim().parse::<f32>(),
+                parts[1].trim().parse::<f32>(),
+                parts[2].trim().parse::<f32>(),
            ) {
-                (Ok(x), Ok(y), Ok(z)) => Some([x, y, z]),
+                (Ok(x), Ok(y), Ok(z)) => Some(NodePositionEntry {
+                    node_id,
+                    position: [x, y, z],
+                }),
                _ => {
-                    tracing::warn!("Skipping unparseable node position entry {idx}: '{triplet}'");
+                    tracing::warn!("Skipping unparseable node position entry {idx}: '{entry}'");
                    None
                }
            }
@@ -170,10 +407,81 @@ pub fn parse_node_positions(input: &str) -> Vec<[f32; 3]> {
        .collect()
 }

+/// Build the `node_id -> position` map the live `NodeInfo` output reads.
+///
+/// Identity is the explicit `node_id:` prefix when the operator gave one, and
+/// the entry's list index otherwise.
+///
+/// This exists as a function rather than a loop inside `main()` because the bug
+/// it fixes was invisible without a test: positions were inserted keyed by list
+/// index and read back by `node_id`, so on any fleet not numbered `0, 1, 2, ...`
+/// every lookup missed and silently fell through to the hardcoded
+/// `[2.0, 0.0, 1.5]` that `--node-positions` exists to replace. The config
+/// looked applied and did nothing.
+pub fn node_positions_by_id(
+    entries: &[NodePositionEntry],
+) -> std::collections::HashMap<u8, [f32; 3]> {
+    let mut map = std::collections::HashMap::new();
+    for (idx, e) in entries.iter().enumerate() {
+        let key = e.node_id.unwrap_or(idx as u8);
+        if let Some(prev) = map.insert(key, e.position) {
+            tracing::warn!(
+                "node position for node {key} given twice ({prev:?} then {:?}); the later entry wins",
+                e.position
+            );
+        }
+    }
+    map
+}
+
+/// Parse node positions from a semicolon-delimited string.
+///
+/// Format: `"x,y,z;x,y,z;..."` where each coordinate is an `f32`.
+/// Malformed entries are skipped with a warning log.
+///
+/// Positional view, for consumers that index the list rather than key it by
+/// node id. Since issue #1866 the fusion path is no longer one of them: it
+/// takes the keyed map from [`node_positions_by_id`] via
+/// `MultistaticFuser::set_node_positions_by_id()`. Use
+/// [`parse_node_position_entries`] where identity is needed.
+pub fn parse_node_positions(input: &str) -> Vec<[f32; 3]> {
+    parse_node_position_entries(input)
+        .into_iter()
+        .map(|e| e.position)
+        .collect()
+}
+
 #[cfg(test)]
 mod tests {
    use super::*;

+    fn fresh_test_model() -> FieldModel {
+        let config = FieldModelConfig {
+            n_links: 1,
+            n_subcarriers: 56,
+            n_modes: 3,
+            min_calibration_frames: 10,
+            min_calibration_duration_s: 0.0,
+            baseline_expiry_s: 2.0,
+        };
+        let mut field = FieldModel::new(config).expect("field model");
+        for index in 0..20 {
+            let phase = index as f64 * 0.1;
+            let observation = vec![(0..56)
+                .map(|subcarrier| {
+                    1.0 + subcarrier as f64 * 0.01 + (phase + subcarrier as f64 * 0.03).sin() * 0.01
+                })
+                .collect()];
+            field
+                .feed_calibration(&observation)
+                .expect("calibration frame");
+        }
+        field
+            .finalize_calibration(1_000_000, 7)
+            .expect("finalize calibration");
+        field
+    }
+
    #[test]
    fn test_parse_node_positions() {
        let positions = parse_node_positions("0,0,1.5;3,0,1.5;1.5,3,1.5");
@@ -203,6 +511,158 @@ mod tests {
        assert_eq!(positions[0], [3.0, 4.0, 5.0]);
    }

+    // ---- Explicit node ids (the indexing-mismatch regression) ----
+
+    /// Positional entries carry no id, so identity falls back to the index.
+    /// This is the ONLY case the old behaviour handled correctly.
+    #[test]
+    fn positional_entries_report_no_explicit_id() {
+        let e = parse_node_position_entries("0,0,1.5;3,0,1.5");
+        assert_eq!(e.len(), 2);
+        assert!(e.iter().all(|x| x.node_id.is_none()));
+        assert_eq!(e[1].position, [3.0, 0.0, 1.5]);
+    }
+
+    /// THE REGRESSION. Positions were stored keyed by list index and read back
+    /// by node_id, so on any fleet not numbered 0,1,2,... every lookup missed
+    /// and fell through to the hardcoded default the option exists to replace.
+    /// Non-sequential ids are what catch that.
+    #[test]
+    fn non_sequential_node_ids_are_preserved() {
+        let e = parse_node_position_entries("11:1,2,3;12:4,5,6;13:7,8,9");
+        assert_eq!(e.len(), 3);
+        assert_eq!(e[0].node_id, Some(11));
+        assert_eq!(e[1].node_id, Some(12));
+        assert_eq!(e[2].node_id, Some(13));
+        assert_eq!(e[2].position, [7.0, 8.0, 9.0]);
+        // The index would have been 0,1,2 -- none of which is a real node here.
+        for (idx, entry) in e.iter().enumerate() {
+            assert_ne!(
+                entry.node_id,
+                Some(idx as u8),
+                "index and node id must not be conflated"
+            );
+        }
+    }
+
+    /// Two-digit ids, and a fleet re-homed to even numbers -- the shape of the
+    /// planned hardware check (nine boards moved from 0..8 to 0,2,4,...,16).
+    #[test]
+    fn two_digit_and_even_numbered_fleet_ids_parse() {
+        let spec = "0:0,0,1;2:1,0,1;4:2,0,1;6:3,0,1;8:4,0,1;10:5,0,1;12:6,0,1;14:7,0,1;16:8,0,1";
+        let e = parse_node_position_entries(spec);
+        assert_eq!(e.len(), 9);
+        let ids: Vec<u8> = e.iter().map(|x| x.node_id.unwrap()).collect();
+        assert_eq!(ids, vec![0, 2, 4, 6, 8, 10, 12, 14, 16]);
+        assert_eq!(e[8].position, [8.0, 0.0, 1.0]);
+    }
+
+    /// A non-zero starting index must work too -- nothing requires node 0.
+    #[test]
+    fn a_fleet_that_does_not_start_at_zero_parses() {
+        let e = parse_node_position_entries("18:1.5,2.5,3.5");
+        assert_eq!(e[0].node_id, Some(18));
+        assert_eq!(e[0].position, [1.5, 2.5, 3.5]);
+    }
+
+    /// Mixing is allowed: an unkeyed entry keeps its index.
+    #[test]
+    fn mixed_forms_keep_their_own_identity() {
+        let e = parse_node_position_entries("0,0,1;7:9,9,9");
+        assert_eq!(e[0].node_id, None);
+        assert_eq!(e[1].node_id, Some(7));
+    }
+
+    /// An unparseable id is skipped rather than silently treated as positional
+    /// -- guessing there would reintroduce the exact ambiguity being removed.
+    #[test]
+    fn an_unparseable_node_id_is_skipped_not_guessed() {
+        let e = parse_node_position_entries("abc:1,2,3;5:4,5,6");
+        assert_eq!(e.len(), 1, "only the well-formed entry survives");
+        assert_eq!(e[0].node_id, Some(5));
+    }
+
+    /// 256 is out of range for a u8 node id and must not wrap to 0.
+    #[test]
+    fn an_out_of_range_node_id_is_rejected() {
+        let e = parse_node_position_entries("256:1,2,3");
+        assert!(e.is_empty(), "256 must not wrap to node 0");
+    }
+
+    /// The positional view stays byte-compatible for the fuser, which indexes
+    /// the list rather than keying it.
+    #[test]
+    fn the_positional_view_is_unchanged_by_explicit_ids() {
+        let p = parse_node_positions("11:1,2,3;12:4,5,6");
+        assert_eq!(p, vec![[1.0, 2.0, 3.0], [4.0, 5.0, 6.0]]);
+    }
+
+    /// The regression itself, at the map that `NodeInfo` actually reads.
+    ///
+    /// The old code inserted keyed by list index and looked up by node_id. On a
+    /// fleet numbered 11,12,13 that map holds keys 0,1,2, so every lookup misses
+    /// and the node reports the hardcoded default. This asserts both halves:
+    /// the real ids resolve, and the indices are absent.
+    #[test]
+    fn the_map_is_keyed_by_node_id_not_list_index() {
+        let entries = parse_node_position_entries("11:1,2,3;12:4,5,6;13:7,8,9");
+        let map = node_positions_by_id(&entries);
+
+        assert_eq!(map.get(&11), Some(&[1.0, 2.0, 3.0]));
+        assert_eq!(map.get(&12), Some(&[4.0, 5.0, 6.0]));
+        assert_eq!(map.get(&13), Some(&[7.0, 8.0, 9.0]));
+
+        for idx in 0u8..3 {
+            assert!(
+                map.get(&idx).is_none(),
+                "list index {idx} must not be a key -- that is the bug: a lookup                  by node_id would miss and fall back to the hardcoded position"
+            );
+        }
+    }
+
+    /// Positional input keeps the old behaviour exactly: index becomes the key.
+    /// This is what made the bug invisible on a 0..8 fleet.
+    #[test]
+    fn positional_input_still_keys_by_index() {
+        let entries = parse_node_position_entries("0,0,1;3,0,1;6,0,1");
+        let map = node_positions_by_id(&entries);
+        assert_eq!(map.get(&0), Some(&[0.0, 0.0, 1.0]));
+        assert_eq!(map.get(&1), Some(&[3.0, 0.0, 1.0]));
+        assert_eq!(map.get(&2), Some(&[6.0, 0.0, 1.0]));
+    }
+
+    /// A re-homed fleet at 0,2,4,...,16 resolves on the real ids, and the odd
+    /// indices in between are absent.
+    #[test]
+    fn an_even_numbered_fleet_resolves_by_id() {
+        let spec = "0:0,0,1;2:1,0,1;4:2,0,1;6:3,0,1;8:4,0,1;10:5,0,1;12:6,0,1;14:7,0,1;16:8,0,1";
+        let map = node_positions_by_id(&parse_node_position_entries(spec));
+        assert_eq!(map.len(), 9);
+        assert_eq!(map.get(&16), Some(&[8.0, 0.0, 1.0]));
+        assert_eq!(map.get(&10), Some(&[5.0, 0.0, 1.0]));
+        // Index-keyed would have produced 0..8; 1,3,5,7 are not real nodes here.
+        for odd in [1u8, 3, 5, 7] {
+            assert!(map.get(&odd).is_none(), "node {odd} does not exist in this fleet");
+        }
+    }
+
+    /// A duplicate id keeps the later entry rather than silently holding two.
+    #[test]
+    fn a_duplicate_node_id_keeps_the_later_entry() {
+        let map = node_positions_by_id(&parse_node_position_entries("4:1,1,1;4:2,2,2"));
+        assert_eq!(map.len(), 1);
+        assert_eq!(map.get(&4), Some(&[2.0, 2.0, 2.0]));
+    }
+
+    /// Whitespace around entries and coordinates is tolerated.
+    #[test]
+    fn whitespace_is_tolerated() {
+        let e = parse_node_position_entries(" 3 : 1.0 , 2.0 , 3.0 ");
+        assert_eq!(e.len(), 1);
+        assert_eq!(e[0].node_id, Some(3));
+        assert_eq!(e[0].position, [1.0, 2.0, 3.0]);
+    }
+
    /// Regression: a freshly-started (`Uncalibrated`) field model must begin
    /// collecting once frames arrive. Before the fix, `maybe_feed_calibration`
    /// only fed while already `Collecting`, but only `feed_calibration` sets
@@ -215,10 +675,7 @@ mod tests {

        // n_subcarriers defaults to 56; one single-link frame of that width.
        let frame = vec![0.5_f64; 56];
-        let mut history: VecDeque<Vec<f64>> = VecDeque::new();
-        history.push_back(frame);
-
-        maybe_feed_calibration(&mut field, &history);
+        assert!(maybe_feed_calibration(&mut field, &frame));

        assert_eq!(
            field.status(),
@@ -231,8 +688,8 @@ mod tests {
            "frame count must advance past 0"
        );

-        // Subsequent frames keep accumulating while Collecting.
-        maybe_feed_calibration(&mut field, &history);
+        // A subsequent unique frame keeps accumulating while Collecting.
+        assert!(maybe_feed_calibration(&mut field, &frame));
        assert_eq!(field.calibration_frame_count(), 2);
    }

@@ -247,10 +704,7 @@ mod tests {

        // 128-wide frame (HT40), NOT the model's 56 — would DimensionMismatch raw.
        let wide = vec![0.5_f64; 128];
-        let mut history: VecDeque<Vec<f64>> = VecDeque::new();
-        history.push_back(wide);
-
-        maybe_feed_calibration(&mut field, &history);
+        assert!(maybe_feed_calibration(&mut field, &wide));

        assert_eq!(
            field.status(),
@@ -263,4 +717,129 @@ mod tests {
            "wide frame must accumulate, not be silently dropped"
        );
    }
+
+    #[test]
+    fn maybe_feed_calibration_rejects_an_empty_observation() {
+        let mut field = FieldModel::new(single_link_config()).expect("field model");
+        assert!(!maybe_feed_calibration(&mut field, &[]));
+        assert_eq!(field.calibration_frame_count(), 0);
+    }
+
+    #[test]
+    fn calibrated_occupancy_is_fresh_model_only_and_normalizes_runtime_frames() {
+        let field = fresh_test_model();
+        let mut history = VecDeque::new();
+        history.push_back(vec![1.02; 128]);
+        let result =
+            calibrated_occupancy(&field, &history, 1_500_000).expect("fresh calibrated inference");
+        assert!(result.person_count <= MAX_SINGLE_LINK_OCCUPANCY);
+        assert!(matches!(
+            result.method,
+            CalibratedOccupancyMethod::Eigenvalue | CalibratedOccupancyMethod::PerturbationEnergy
+        ));
+        assert_eq!(calibrated_occupancy(&field, &history, 4_000_000), None);
+        assert_eq!(
+            calibrated_occupancy(&field, &VecDeque::new(), 1_500_000),
+            None
+        );
+    }
+
+    #[test]
+    fn occupancy_falls_back_after_expiry_without_a_process_restart() {
+        let field = fresh_test_model();
+        let baseline = field.modes().unwrap().baseline[0].clone();
+        let history: VecDeque<Vec<f64>> =
+            (0..OCCUPANCY_WINDOW).map(|_| baseline.clone()).collect();
+
+        assert_eq!(field.status(), CalibrationStatus::Fresh);
+        assert_eq!(
+            calibration_status_at(&field, 1_500_000),
+            CalibrationStatus::Fresh
+        );
+        assert_eq!(
+            occupancy_or_fallback(&field, &history, 1_500_000, 0.0, 0),
+            0,
+            "a fresh field model may resolve its learned baseline as empty"
+        );
+
+        assert_eq!(field.status(), CalibrationStatus::Fresh);
+        assert_eq!(
+            calibration_status_at(&field, 4_000_000),
+            CalibrationStatus::Expired
+        );
+        assert_eq!(
+            occupancy_or_fallback(&field, &history, 4_000_000, 0.0, 0),
+            score_to_person_count(0.0, 0),
+            "an expired in-memory model must fall back even though its cached status is fresh"
+        );
+    }
+
+    #[test]
+    fn adaptive_runtime_reference_scores_empty_and_rejects_shift() {
+        let config = FieldModelConfig {
+            n_links: 1,
+            n_subcarriers: 56,
+            n_modes: 3,
+            min_calibration_frames: 500,
+            min_calibration_duration_s: 0.0,
+            baseline_expiry_s: 60.0,
+        };
+        let mut field = FieldModel::new(config).expect("field model");
+        let mut calibration = Vec::new();
+        for frame_index in 0..600 {
+            let time = frame_index as f64 * 0.071;
+            let frame: Vec<f64> = (0..56)
+                .map(|subcarrier| {
+                    let carrier = subcarrier as f64;
+                    18.0 + carrier * 0.08
+                        + (time + carrier * 0.13).sin() * 0.8
+                        + (time * 0.37 + carrier * 0.031).cos() * 0.35
+                })
+                .collect();
+            field.feed_calibration(&[frame.clone()]).unwrap();
+            calibration.push(frame);
+        }
+        field.finalize_calibration(1_000_000, 7).unwrap();
+
+        let empty_history: VecDeque<Vec<f64>> = calibration[550..600].iter().cloned().collect();
+        let empty = calibrated_occupancy(&field, &empty_history, 1_500_000)
+            .expect("adaptive perturbation result");
+        assert_eq!(empty.person_count, 0);
+        let background = bootstrap_background_match(&field, &empty_history, 1_500_000)
+            .expect("background score");
+        assert!(background.matches_empty);
+        assert_eq!(background.reference_window_count, 12);
+        assert!(background.reliable);
+        assert_eq!(background.maturity, 0.6);
+        assert!(background.normalized_residual_z.is_some());
+        assert!(background
+            .score
+            .is_some_and(|score| (0.5..=1.0).contains(&score)));
+
+        let short_history: VecDeque<Vec<f64>> = empty_history.iter().take(49).cloned().collect();
+        assert!(!bootstrap_empty_prior_applies(
+            &field,
+            &short_history,
+            1_500_000
+        ));
+
+        let shifted_history: VecDeque<Vec<f64>> = calibration[550..600]
+            .iter()
+            .map(|frame| {
+                frame
+                    .iter()
+                    .enumerate()
+                    .map(|(index, value)| value + if index % 3 == 0 { 8.0 } else { -5.0 })
+                    .collect()
+            })
+            .collect();
+        let shifted = calibrated_occupancy(&field, &shifted_history, 1_500_000)
+            .expect("shifted perturbation result");
+        assert!(shifted.person_count >= 1);
+        let shifted_background = bootstrap_background_match(&field, &shifted_history, 1_500_000)
+            .expect("shifted background result");
+        assert!(!shifted_background.matches_empty);
+        assert_eq!(shifted_background.score, Some(0.0));
+        assert!(shifted_background.reliable);
+    }
 }
@@ -9,6 +9,7 @@
 //! - Real-time CSI introspection / low-latency tap (`introspection`, ADR-099)

 pub mod bearer_auth;
+pub mod bootstrap_baseline;
 pub mod browser_session;
 pub mod ws_ticket;
 pub mod cli;
@@ -0,0 +1,124 @@
+//! Bounded summaries for ADR-323 Realtek RTL8721Dx (AmebaDplus) 1x1 CSI frames.
+
+use serde::Serialize;
+use wifi_densepose_hardware::realtek_csi::{CsiFlags, CsiFrame};
+
+#[derive(Debug, Clone, PartialEq, Serialize)]
+pub(crate) struct RealtekCsiSnapshot {
+    pub event_type: &'static str,
+    pub source: &'static str,
+    pub csi_mode: &'static str,
+    pub node_id: u8,
+    pub sequence: u32,
+    pub timestamp_us: u32,
+    pub peer_mac: String,
+    pub trig_mac: String,
+    pub channel: u8,
+    pub bandwidth_mhz: u16,
+    pub rx_rate: u8,
+    pub protocol_mode: String,
+    pub num_sub_carrier: u16,
+    pub num_bit_per_tone: u8,
+    pub decimation: u8,
+    pub rssi_dbm: i8,
+    pub rxsc: u8,
+    pub csi_valid: bool,
+    pub synthetic: bool,
+    pub mean_amplitude: Option<f32>,
+    pub peak_amplitude: Option<f32>,
+}
+
+impl RealtekCsiSnapshot {
+    pub(crate) fn from_frame(frame: &CsiFrame) -> Self {
+        let synthetic = frame.flags.contains(CsiFlags::SYNTHETIC);
+        let (mean_amplitude, peak_amplitude) = amplitude_summary(frame);
+        Self {
+            event_type: "realtek_csi",
+            source: if synthetic {
+                "realtek_csi:simulated"
+            } else {
+                "realtek_csi"
+            },
+            csi_mode: match frame.csi_mode {
+                wifi_densepose_hardware::realtek_csi::CsiMode::Passive => "passive",
+                wifi_densepose_hardware::realtek_csi::CsiMode::Active => "active",
+                wifi_densepose_hardware::realtek_csi::CsiMode::BoardToBoard => "board_to_board",
+            },
+            node_id: frame.node_id,
+            sequence: frame.sequence,
+            timestamp_us: frame.timestamp_us,
+            peer_mac: mac_string(&frame.peer_mac),
+            trig_mac: mac_string(&frame.trig_mac),
+            channel: frame.channel,
+            bandwidth_mhz: if frame.bandwidth == 1 { 40 } else { 20 },
+            rx_rate: frame.rx_rate,
+            protocol_mode: format!("{:?}", frame.protocol_mode).to_ascii_lowercase(),
+            num_sub_carrier: frame.num_sub_carrier,
+            num_bit_per_tone: frame.num_bit_per_tone,
+            decimation: frame.decimation,
+            rssi_dbm: frame.rssi_dbm,
+            rxsc: frame.rxsc,
+            csi_valid: frame.csi_valid,
+            synthetic,
+            mean_amplitude,
+            peak_amplitude,
+        }
+    }
+}
+
+fn mac_string(mac: &[u8; 6]) -> String {
+    mac.iter()
+        .map(|b| format!("{b:02x}"))
+        .collect::<Vec<_>>()
+        .join(":")
+}
+
+fn amplitude_summary(frame: &CsiFrame) -> (Option<f32>, Option<f32>) {
+    if frame.payload.is_empty() {
+        return (None, None);
+    }
+    let amplitudes: Vec<f32> = frame
+        .payload
+        .iter()
+        .map(|(i, q)| (*i as f32).hypot(*q as f32))
+        .collect();
+    let mean = amplitudes.iter().sum::<f32>() / amplitudes.len() as f32;
+    let peak = amplitudes.into_iter().max_by(f32::total_cmp);
+    (Some(mean), peak)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use wifi_densepose_hardware::realtek_csi::simulator::{RealtekCsiSimulator, SimulatorConfig};
+
+    #[test]
+    fn simulator_summary_preserves_dimensions_and_provenance() {
+        let mut sim = RealtekCsiSimulator::new(SimulatorConfig::default()).unwrap();
+        let snapshot = RealtekCsiSnapshot::from_frame(&sim.next_frame());
+        assert_eq!(snapshot.source, "realtek_csi:simulated");
+        assert_eq!(snapshot.num_sub_carrier, 52);
+        assert_eq!(snapshot.csi_mode, "passive");
+        assert!(snapshot.mean_amplitude.unwrap() > 0.0);
+        assert!(snapshot.peak_amplitude.unwrap() >= snapshot.mean_amplitude.unwrap());
+    }
+
+    #[test]
+    fn source_string_is_distinct_from_realtek_radar() {
+        let mut sim = RealtekCsiSimulator::new(SimulatorConfig::default()).unwrap();
+        let snapshot = RealtekCsiSnapshot::from_frame(&sim.next_frame());
+        // Must never collapse to the bare "realtek"/"realtek:simulated" source
+        // strings already owned by the RTL8720F radar path (realtek_radar.rs) —
+        // effective_source()'s prefix matching in main.rs depends on this.
+        assert_ne!(snapshot.source, "realtek");
+        assert_ne!(snapshot.source, "realtek:simulated");
+        assert!(snapshot.source.starts_with("realtek_csi"));
+    }
+
+    #[test]
+    fn mac_addresses_are_formatted_colon_separated() {
+        let mut sim = RealtekCsiSimulator::new(SimulatorConfig::default()).unwrap();
+        let snapshot = RealtekCsiSnapshot::from_frame(&sim.next_frame());
+        assert_eq!(snapshot.peer_mac, "a4:39:b3:a4:be:2d");
+    }
+}
@@ -544,6 +544,10 @@ impl AppStateInner {
    pub fn person_count(&self) -> usize {
        use crate::csi::score_to_person_count;
        use crate::field_bridge;
+        let observed_at_us = std::time::SystemTime::now()
+            .duration_since(std::time::UNIX_EPOCH)
+            .map(|duration| duration.as_micros() as u64)
+            .unwrap_or(0);
        match self.field_model.as_ref() {
            Some(fm) => {
                let history = if !self.frame_history.is_empty() {
@@ -559,6 +563,7 @@ impl AppStateInner {
                field_bridge::occupancy_or_fallback(
                    fm,
                    history,
+                    observed_at_us,
                    self.smoothed_person_score,
                    self.prev_person_count,
                )
@@ -346,6 +346,31 @@ impl VitalSignDetector {
        self.frame_count = 0;
    }

+    /// Retune temporal windows to an observed CSI clock. Changes smaller than
+    /// twenty percent are ignored to avoid resetting on normal arrival jitter.
+    /// A real clock change clears history so samples from different clocks are
+    /// never interpreted in one spectrum.
+    pub fn reconfigure_sample_rate(&mut self, sample_rate: f64) -> bool {
+        if !sample_rate.is_finite() || sample_rate < 1.0 {
+            return false;
+        }
+        let relative_change = (sample_rate - self.sample_rate).abs() / self.sample_rate.max(1.0);
+        if relative_change < 0.20 {
+            return false;
+        }
+        self.sample_rate = sample_rate;
+        self.breathing_capacity =
+            ((sample_rate * self.breathing_window_secs) as usize).max(1);
+        self.heartbeat_capacity =
+            ((sample_rate * self.heartbeat_window_secs) as usize).max(1);
+        self.reset();
+        true
+    }
+
+    pub fn sample_rate_hz(&self) -> f64 {
+        self.sample_rate
+    }
+
    /// Current buffer fill levels for diagnostics.
    /// Returns (breathing_len, breathing_capacity, heartbeat_len, heartbeat_capacity).
    pub fn buffer_status(&self) -> (usize, usize, usize, usize) {
@@ -842,6 +867,22 @@ mod tests {
        assert_eq!(hb_len, 0);
    }

+    #[test]
+    fn measured_clock_reconfigures_once_and_clears_mixed_history() {
+        let mut detector = VitalSignDetector::new(20.0);
+        let amp = vec![10.0; 56];
+        let phase = vec![0.0; 56];
+        for _ in 0..32 {
+            detector.process_frame(&amp, &phase);
+        }
+        assert!(!detector.reconfigure_sample_rate(18.0));
+        assert_eq!(detector.sample_rate_hz(), 20.0);
+        assert!(detector.reconfigure_sample_rate(12.0));
+        assert_eq!(detector.sample_rate_hz(), 12.0);
+        assert_eq!(detector.buffer_status(), (0, 360, 0, 180));
+        assert!(!detector.reconfigure_sample_rate(f64::NAN));
+    }
+
    #[test]
    fn test_vital_signs_default() {
        let vs = VitalSigns::default();
@@ -26,6 +26,7 @@
 //! - `ruvector-attn-mincut` for cross-node spectrogram attention gating
 //! - `ruvector-mincut` for person separation (DynamicMinCut)

+use std::collections::HashMap;
 use std::sync::Arc;

 use super::cir::{CirConfig, CirEstimator};
@@ -72,6 +73,12 @@ pub struct FusedSensingFrame {
    /// Per-node multi-band frames (preserved for geometry computations).
    pub node_frames: Vec<MultiBandCsiFrame>,
    /// Node positions (x, y, z) in meters from deployment configuration.
+    ///
+    /// Parallel to [`Self::node_frames`]: `node_positions[i]` is the
+    /// configured position of `node_frames[i].node_id`, resolved by identity
+    /// rather than by rank (issue #1866). Nodes with no configured position
+    /// appear at the origin. Index `i` is this cycle's cohort rank, which is
+    /// *not* a node id -- read the id from the paired frame.
    pub node_positions: Vec<[f32; 3]>,
    /// Number of active nodes contributing to this frame.
    pub active_nodes: usize,
@@ -147,8 +154,31 @@ impl MultistaticConfig {
    /// maximum legitimate spread between two paired node frames in one cycle is
    /// the full cycle length `tdm_total_slots × slot_duration_us` (last slot vs
    /// first slot). The hard guard is set to that cycle length plus 20% jitter
-    /// headroom; the soft guard to ~⅓ of the cycle (a normal adjacent-slot pair
-    /// fuses cleanly, a near-full-cycle spread is flagged as loose alignment).
+    /// headroom; the soft guard to the schedule's own **designed stagger**,
+    /// `(slots - 1) * slot_duration_us` -- the offset between the first and
+    /// last slot, which is the spread a complete, healthy cycle produces.
+    ///
+    /// # Why not ~⅓ of the cycle (issue #1866-adjacent, corrected)
+    ///
+    /// The soft guard was previously `cycle_us / 3`, reasoned about as "a
+    /// normal *adjacent-slot pair* fuses cleanly". But [`MultistaticFuser::fuse_scored`]
+    /// does not compare pairs -- it takes `max(timestamp) - min(timestamp)`
+    /// across the **whole cohort**, so the spread it measures is always the
+    /// first-to-last offset, `(N - 1)` slots. Against that:
+    ///
+    /// ```text
+    ///   soft < stagger  <=>  N*slot/3 < (N-1)*slot  <=>  N/3 < N-1  <=>  N > 1.5
+    /// ```
+    ///
+    /// which holds for **every** `N >= 2`. The derived soft guard therefore
+    /// never covered the schedule it was derived from, at any fleet size, and
+    /// a complete healthy cycle was flagged as a `TimestampMismatch`
+    /// contradiction -- which demotes the BFLD privacy class one step
+    /// (ADR-137 §2.7 -> ADR-141) and suppresses raw outputs.
+    ///
+    /// The doc example below is the smallest demonstration: the 2-slot mesh
+    /// whose **measured** 18,194 µs spread motivated this constructor derived
+    /// a 12,000 µs soft guard, below its own motivating measurement.
    ///
    /// `tdm_total_slots` is clamped to ≥ 1. All other fields take their
    /// [`Default`] values.
@@ -160,6 +190,9 @@ impl MultistaticConfig {
    /// // reported 18,194 µs 2-slot spread.
    /// let cfg = MultistaticConfig::for_tdm_schedule(2, 18_000);
    /// assert!(cfg.guard_interval_us >= 18_194);
+    /// // ...and the soft guard now covers it too, so a healthy 2-slot cycle
+    /// // is not recorded as a contradiction.
+    /// assert!(cfg.soft_guard_us >= 18_194);
    /// ```
    #[must_use]
    pub fn for_tdm_schedule(tdm_total_slots: usize, slot_duration_us: u64) -> Self {
@@ -167,8 +200,19 @@ impl MultistaticConfig {
        let cycle_us = slots.saturating_mul(slot_duration_us);
        // +20% jitter headroom on the full cycle.
        let guard_interval_us = cycle_us.saturating_add(cycle_us / 5).max(1);
-        // Soft band at ~⅓ cycle, kept strictly below the hard guard.
-        let soft_guard_us = (cycle_us / 3).clamp(1, guard_interval_us.saturating_sub(1).max(1));
+        // Soft band at the schedule's designed stagger -- the first-to-last
+        // slot offset, which is what `fuse_scored` measures. Kept strictly
+        // below the hard guard, so a spread approaching a full cycle is still
+        // flagged as loose alignment.
+        // +20% jitter headroom, mirroring the hard guard: the *nominal* stagger
+        // is not the observed one. The 2-slot mesh below has an 18,000 us
+        // nominal stagger but a MEASURED 18,194 us spread, so a bare nominal
+        // bound would flag the very cycle it was derived from. Always strictly
+        // below the hard guard, since stagger < cycle.
+        let stagger_us = slots.saturating_sub(1).saturating_mul(slot_duration_us);
+        let soft_guard_us = stagger_us
+            .saturating_add(stagger_us / 5)
+            .clamp(1, guard_interval_us.saturating_sub(1).max(1));
        Self {
            guard_interval_us,
            soft_guard_us,
@@ -191,8 +235,16 @@ impl MultistaticConfig {
 /// disable the CIR path and keep the legacy frequency-domain coherence only.
 pub struct MultistaticFuser {
    config: MultistaticConfig,
-    /// Node positions in 3D space (meters).
-    node_positions: Vec<[f32; 3]>,
+    /// Node positions in 3D space (meters), keyed by node id (issue #1866).
+    ///
+    /// Keyed rather than indexed because [`Self::fuse`] receives a *compacted*
+    /// cohort: `node_frames_from_states_with_guard` drops nodes that are
+    /// stale, outside the timestamp guard, or have an empty history. Under
+    /// index addressing, one node missing a single beacon re-ranks every node
+    /// above it and silently hands them their neighbour's coordinates. Each
+    /// `MultiBandCsiFrame` carries its own `node_id`, so the position is
+    /// looked up by identity and a silent node moves nobody.
+    node_positions: HashMap<u8, [f32; 3]>,
    /// Optional shared CIR estimator (ADR-134).  `None` = legacy path only.
    cir_estimator: Option<Arc<CirEstimator>>,
 }
@@ -212,7 +264,7 @@ impl MultistaticFuser {
    pub fn new() -> Self {
        Self {
            config: MultistaticConfig::default(),
-            node_positions: Vec::new(),
+            node_positions: HashMap::new(),
            cir_estimator: None,
        }
    }
@@ -221,7 +273,7 @@ impl MultistaticFuser {
    pub fn with_config(config: MultistaticConfig) -> Self {
        Self {
            config,
-            node_positions: Vec::new(),
+            node_positions: HashMap::new(),
            cir_estimator: None,
        }
    }
@@ -267,11 +319,39 @@ impl MultistaticFuser {
        fuser
    }

-    /// Set node positions for geometric diversity computations.
+    /// Set node positions from a positional list (**legacy compatibility**).
+    ///
+    /// The list index is the node id: `positions[i]` belongs to node `i`. That
+    /// is the meaning the `--node-positions` flag has always carried when its
+    /// entries are given without an explicit `node_id:` prefix, so this
+    /// mapping is preserved exactly rather than reinterpreted.
+    ///
+    /// This is only correct for fleets whose ids are dense and zero-based.
+    /// Prefer [`Self::set_node_positions_by_id`], which states the identity
+    /// instead of inferring it from ordering.
    pub fn set_node_positions(&mut self, positions: Vec<[f32; 3]>) {
+        self.node_positions = positions
+            .into_iter()
+            .enumerate()
+            .map(|(idx, position)| (idx as u8, position))
+            .collect();
+    }
+
+    /// Set node positions keyed by node id (issue #1866, preferred).
+    ///
+    /// The position travels with the board it was measured for. Nodes absent
+    /// from the map fuse at the origin, exactly as before; nodes present but
+    /// not currently reporting cost nothing and shift nobody.
+    pub fn set_node_positions_by_id(&mut self, positions: HashMap<u8, [f32; 3]>) {
        self.node_positions = positions;
    }

+    /// Return the configured position for one node id, if any.
+    #[must_use]
+    pub fn node_position(&self, node_id: u8) -> Option<[f32; 3]> {
+        self.node_positions.get(&node_id).copied()
+    }
+
    /// Return the configured hard timestamp guard in microseconds.
    ///
    /// Callers that assemble frames before invoking [`Self::fuse`] use this
@@ -283,11 +363,33 @@ impl MultistaticFuser {
        self.config.guard_interval_us
    }

-    /// Return the current node positions.
-    pub fn node_positions(&self) -> &[[f32; 3]] {
+    /// Return the configured positions keyed by node id.
+    #[must_use]
+    pub fn node_positions_by_id(&self) -> &HashMap<u8, [f32; 3]> {
        &self.node_positions
    }

+    /// Return the configured positions as a dense id-indexed list
+    /// (**legacy compatibility view**).
+    ///
+    /// Entry `i` is node `i`'s position, with unconfigured ids filled at the
+    /// origin, so this round-trips [`Self::set_node_positions`]. It is a view
+    /// of the configuration, *not* of what any particular fusion cycle used —
+    /// a cycle's cohort is compacted, so read
+    /// [`FusedSensingFrame::node_positions`] alongside its `node_frames` for
+    /// that.
+    #[must_use]
+    pub fn node_positions(&self) -> Vec<[f32; 3]> {
+        let Some(&max_id) = self.node_positions.keys().max() else {
+            return Vec::new();
+        };
+        let mut dense = vec![[0.0_f32, 0.0, 0.0]; max_id as usize + 1];
+        for (&id, &position) in &self.node_positions {
+            dense[id as usize] = position;
+        }
+        dense
+    }
+
    /// Fuse multiple node frames into a single `FusedSensingFrame`.
    ///
    /// When only one node is provided, falls back to single-node mode
@@ -360,11 +462,19 @@ impl MultistaticFuser {
        timestamps.sort_unstable();
        let timestamp_us = timestamps[timestamps.len() / 2];

-        // Build node positions list, filling with origin for unknown nodes
-        let positions: Vec<[f32; 3]> = (0..n_nodes)
-            .map(|i| {
+        // Build the node positions list parallel to `node_frames`, resolving
+        // each entry by that frame's own `node_id` (issue #1866). The cohort
+        // handed to `fuse` is compacted -- stale, out-of-guard and
+        // empty-history nodes are already dropped -- so a frame's index here
+        // is its rank in this cycle, not its identity. Addressing by index
+        // gave every node above a gap its neighbour's coordinates whenever a
+        // single board missed a beacon. Unknown nodes still fill with the
+        // origin, unchanged.
+        let positions: Vec<[f32; 3]> = node_frames
+            .iter()
+            .map(|frame| {
                self.node_positions
-                    .get(i)
+                    .get(&frame.node_id)
                    .copied()
                    .unwrap_or([0.0, 0.0, 0.0])
            })
@@ -964,6 +1074,88 @@ mod tests {
        );
    }

+    /// A derived schedule must not flag its own healthy cycle as a
+    /// contradiction.
+    ///
+    /// Every prior assertion on `soft_guard_us` was *relational* (`soft <
+    /// hard`, `soft >= 1`), so nothing compared it to a spread the schedule
+    /// actually produces -- which is how `cycle/3` survived. `fuse_scored`
+    /// measures `max - min` across the whole cohort, i.e. `(N-1)` slots, so
+    /// that is what the soft guard must cover.
+    #[test]
+    fn derived_soft_guard_covers_the_schedules_own_stagger() {
+        for (slots, slot_us) in [
+            (2_usize, 18_000_u64), // the measured 2-slot mesh in the doc comment
+            (3, 27_000),
+            (4, 12_500),
+            (6, 33_300),
+            (9, 35_600),  // a nine-node fleet: 320 ms cycle
+            (13, 36_900),
+        ] {
+            let cfg = MultistaticConfig::for_tdm_schedule(slots, slot_us);
+            // Nominal stagger; the derived guard must clear it WITH headroom,
+            // because observed spread runs slightly over nominal (18,194 us
+            // measured against an 18,000 us nominal 2-slot stagger).
+            let stagger = (slots as u64 - 1) * slot_us;
+            assert!(
+                cfg.soft_guard_us > stagger,
+                "{slots} slots x {slot_us} us: soft guard {} us is below the \
+                 schedule's own first-to-last stagger of {stagger} us, so a \
+                 complete healthy cycle is recorded as a TimestampMismatch \
+                 contradiction and demotes the privacy class",
+                cfg.soft_guard_us
+            );
+            assert!(cfg.soft_guard_us < cfg.guard_interval_us);
+        }
+    }
+
+    /// End to end: a full, evenly-staggered cycle fuses with **no**
+    /// contradiction under its own derived config.
+    #[test]
+    fn a_healthy_full_cycle_raises_no_contradiction() {
+        let (slots, slot_us) = (9_usize, 35_600_u64);
+        let cfg = MultistaticConfig::for_tdm_schedule(slots, slot_us);
+        let fuser = MultistaticFuser::with_config(cfg.clone());
+
+        // Node k transmits in slot k -- the schedule working exactly as designed.
+        let frames: Vec<MultiBandCsiFrame> = (0..slots)
+            .map(|k| make_node_frame(k as u8, k as u64 * slot_us, 56, 1.0))
+            .collect();
+
+        let (_fused, score) = fuser
+            .fuse_scored(&frames, 0.0)
+            .expect("a healthy cycle must fuse");
+        assert!(
+            !score.forces_privacy_demotion(),
+            "a complete {slots}-slot cycle is the schedule operating normally \
+             and must not demote the privacy class; flags: {:?}",
+            score.contradiction_flags
+        );
+    }
+
+    /// The soft band still does its job: a spread beyond the designed stagger
+    /// is flagged.
+    #[test]
+    fn a_spread_beyond_the_stagger_is_still_flagged() {
+        let (slots, slot_us) = (9_usize, 35_600_u64);
+        let cfg = MultistaticConfig::for_tdm_schedule(slots, slot_us);
+        let hard = cfg.guard_interval_us;
+        let fuser = MultistaticFuser::with_config(cfg);
+
+        // Two nodes, inside the hard guard but wider than a full cycle's stagger.
+        let late = hard - 1;
+        let frames = vec![
+            make_node_frame(0, 0, 56, 1.0),
+            make_node_frame(1, late, 56, 1.0),
+        ];
+        let (_f, score) = fuser.fuse_scored(&frames, 0.0).expect("within hard guard");
+        assert!(
+            score.forces_privacy_demotion(),
+            "a spread of {late} us exceeds the designed stagger and must still \
+             be recorded as loose alignment"
+        );
+    }
+
    /// The derived soft guard stays strictly below the hard guard, and a
    /// degenerate (0-slot) schedule clamps to a usable config.
    #[test]
@@ -1064,10 +1256,16 @@ mod tests {

    #[test]
    fn node_positions_set_and_retrieved() {
+        // The legacy positional setter round-trips through the dense view:
+        // index i in, index i out. Storage is keyed by id underneath, and
+        // `positions[i]` is documented to mean node i.
        let mut fuser = MultistaticFuser::new();
        let positions = vec![[0.0, 0.0, 1.0], [3.0, 0.0, 1.0]];
        fuser.set_node_positions(positions.clone());
-        assert_eq!(fuser.node_positions(), &positions[..]);
+        assert_eq!(fuser.node_positions(), positions);
+        assert_eq!(fuser.node_position(0), Some([0.0, 0.0, 1.0]));
+        assert_eq!(fuser.node_position(1), Some([3.0, 0.0, 1.0]));
+        assert_eq!(fuser.node_position(2), None);
    }

    #[test]
@@ -1083,6 +1281,255 @@ mod tests {
        assert_eq!(fused.node_positions[1], [0.0, 0.0, 0.0]); // default
    }

+    /// Issue #1866 regressions: a fused contribution must carry the position
+    /// belonging to its own `node_id`, under every cohort shape the live
+    /// collector can produce.
+    ///
+    /// `node_frames_from_states_with_guard` hands `fuse` a *compacted* cohort:
+    /// stale, out-of-guard and empty-history nodes are already gone. So the
+    /// index of a frame is its rank in this cycle, never its identity.
+    mod positions_keyed_by_node_id {
+        use super::*;
+
+        fn positions(entries: &[(u8, [f32; 3])]) -> HashMap<u8, [f32; 3]> {
+            entries.iter().copied().collect()
+        }
+
+        /// Every frame gets its own node's coordinates -- the core assertion.
+        fn assert_each_frame_owns_its_position(
+            configured: &HashMap<u8, [f32; 3]>,
+            frames: &[MultiBandCsiFrame],
+        ) {
+            let mut fuser = MultistaticFuser::new();
+            fuser.set_node_positions_by_id(configured.clone());
+            let fused = fuser.fuse(frames).expect("cohort fuses");
+
+            assert_eq!(fused.node_positions.len(), frames.len());
+            for (frame, position) in fused.node_frames.iter().zip(&fused.node_positions) {
+                let expected = configured
+                    .get(&frame.node_id)
+                    .copied()
+                    .unwrap_or([0.0, 0.0, 0.0]);
+                assert_eq!(
+                    *position, expected,
+                    "node {} received the wrong position",
+                    frame.node_id
+                );
+            }
+        }
+
+        #[test]
+        fn sparse_node_ids_each_get_their_own_position() {
+            // Real fleets use logical ids like 11/12/13. Under rank addressing
+            // every one of these resolved to the origin, because indices
+            // 11..13 do not exist in a 3-entry list.
+            let configured = positions(&[
+                (11, [1.0, 0.0, 0.0]),
+                (12, [2.0, 0.0, 0.0]),
+                (13, [3.0, 0.0, 0.0]),
+            ]);
+            let frames = vec![
+                make_node_frame(11, 100, 56, 1.0),
+                make_node_frame(12, 101, 56, 1.0),
+                make_node_frame(13, 102, 56, 1.0),
+            ];
+            assert_each_frame_owns_its_position(&configured, &frames);
+
+            let mut fuser = MultistaticFuser::new();
+            fuser.set_node_positions_by_id(configured);
+            let fused = fuser.fuse(&frames).expect("cohort fuses");
+            assert_eq!(fused.node_positions[0], [1.0, 0.0, 0.0]);
+            assert_eq!(fused.node_positions[2], [3.0, 0.0, 0.0]);
+        }
+
+        #[test]
+        fn configuration_order_does_not_change_any_position() {
+            // Insertion order must be irrelevant: identity is stated, not
+            // inferred from where an entry sat in the config.
+            let ascending = positions(&[
+                (3, [3.0, 0.0, 0.0]),
+                (5, [5.0, 0.0, 0.0]),
+                (9, [9.0, 0.0, 0.0]),
+            ]);
+            let reversed = positions(&[
+                (9, [9.0, 0.0, 0.0]),
+                (5, [5.0, 0.0, 0.0]),
+                (3, [3.0, 0.0, 0.0]),
+            ]);
+            let frames = vec![
+                make_node_frame(3, 100, 56, 1.0),
+                make_node_frame(5, 101, 56, 1.0),
+                make_node_frame(9, 102, 56, 1.0),
+            ];
+
+            let mut a = MultistaticFuser::new();
+            a.set_node_positions_by_id(ascending);
+            let mut b = MultistaticFuser::new();
+            b.set_node_positions_by_id(reversed);
+
+            assert_eq!(
+                a.fuse(&frames).expect("fuses").node_positions,
+                b.fuse(&frames).expect("fuses").node_positions
+            );
+        }
+
+        #[test]
+        fn a_silent_node_does_not_move_the_others() {
+            // THE REASON THIS IS KEYED BY ID. Node 2 misses a beacon and drops
+            // out of the cohort. Under rank addressing nodes 3 and 4 shift
+            // down one slot and silently inherit their neighbours' coordinates
+            // -- a fleet-wide position error caused by one dropped frame.
+            let configured = positions(&[
+                (1, [1.0, 0.0, 0.0]),
+                (2, [2.0, 0.0, 0.0]),
+                (3, [3.0, 0.0, 0.0]),
+                (4, [4.0, 0.0, 0.0]),
+            ]);
+            let mut fuser = MultistaticFuser::new();
+            fuser.set_node_positions_by_id(configured);
+
+            let all_up = vec![
+                make_node_frame(1, 100, 56, 1.0),
+                make_node_frame(2, 101, 56, 1.0),
+                make_node_frame(3, 102, 56, 1.0),
+                make_node_frame(4, 103, 56, 1.0),
+            ];
+            let two_silent = vec![
+                make_node_frame(1, 100, 56, 1.0),
+                make_node_frame(3, 102, 56, 1.0),
+                make_node_frame(4, 103, 56, 1.0),
+            ];
+
+            let full = fuser.fuse(&all_up).expect("fuses");
+            let gapped = fuser.fuse(&two_silent).expect("fuses");
+
+            assert_eq!(full.node_positions[2], [3.0, 0.0, 0.0]);
+            assert_eq!(full.node_positions[3], [4.0, 0.0, 0.0]);
+            // Node 3 is now at rank 1 and node 4 at rank 2, but both keep
+            // their own coordinates.
+            assert_eq!(gapped.node_positions[0], [1.0, 0.0, 0.0]);
+            assert_eq!(gapped.node_positions[1], [3.0, 0.0, 0.0]);
+            assert_eq!(gapped.node_positions[2], [4.0, 0.0, 0.0]);
+        }
+
+        #[test]
+        fn join_and_leave_churn_never_reassigns_a_position() {
+            // Walk a node through leave -> rejoin. Every cohort shape must
+            // still pair each frame with its own configured coordinates.
+            let configured = positions(&[
+                (0, [0.0, 0.0, 0.0]),
+                (1, [1.0, 1.0, 0.0]),
+                (2, [2.0, 2.0, 0.0]),
+                (3, [3.0, 3.0, 0.0]),
+            ]);
+            let cohorts: Vec<Vec<u8>> = vec![
+                vec![0, 1, 2, 3],
+                vec![0, 2, 3],
+                vec![2, 3],
+                vec![3],
+                vec![0, 3],
+                vec![0, 1, 2, 3],
+            ];
+            for ids in cohorts {
+                let frames: Vec<MultiBandCsiFrame> = ids
+                    .iter()
+                    .enumerate()
+                    .map(|(i, &id)| make_node_frame(id, 100 + i as u64, 56, 1.0))
+                    .collect();
+                assert_each_frame_owns_its_position(&configured, &frames);
+            }
+        }
+
+        #[test]
+        fn a_configured_but_absent_node_costs_nothing() {
+            // Positions may be configured for boards that are not reporting.
+            // They must not consume a slot or displace anyone.
+            let configured = positions(&[
+                (1, [1.0, 0.0, 0.0]),
+                (7, [7.0, 0.0, 0.0]),
+                (42, [42.0, 0.0, 0.0]),
+            ]);
+            let frames = vec![
+                make_node_frame(1, 100, 56, 1.0),
+                make_node_frame(7, 101, 56, 1.0),
+            ];
+            assert_each_frame_owns_its_position(&configured, &frames);
+
+            let mut fuser = MultistaticFuser::new();
+            fuser.set_node_positions_by_id(configured);
+            let fused = fuser.fuse(&frames).expect("fuses");
+            assert_eq!(fused.node_positions.len(), 2);
+            assert_eq!(fused.node_positions[1], [7.0, 0.0, 0.0]);
+        }
+
+        #[test]
+        fn an_unconfigured_node_still_fuses_at_the_origin() {
+            // Unchanged fallback behaviour: unknown node -> origin, and it
+            // must not disturb its neighbours.
+            let configured = positions(&[(1, [1.0, 0.0, 0.0]), (3, [3.0, 0.0, 0.0])]);
+            let frames = vec![
+                make_node_frame(1, 100, 56, 1.0),
+                make_node_frame(2, 101, 56, 1.0),
+                make_node_frame(3, 102, 56, 1.0),
+            ];
+            assert_each_frame_owns_its_position(&configured, &frames);
+
+            let mut fuser = MultistaticFuser::new();
+            fuser.set_node_positions_by_id(configured);
+            let fused = fuser.fuse(&frames).expect("fuses");
+            assert_eq!(fused.node_positions[1], [0.0, 0.0, 0.0]);
+        }
+
+        #[test]
+        fn legacy_positional_setter_still_means_index_equals_node_id() {
+            // Documented compatibility mapping: a bare `--node-positions`
+            // list has always meant "the i-th entry is node i". Preserved
+            // exactly, so existing deployments are unaffected.
+            let mut fuser = MultistaticFuser::new();
+            fuser.set_node_positions(vec![
+                [0.0, 0.0, 0.0],
+                [1.0, 0.0, 0.0],
+                [2.0, 0.0, 0.0],
+            ]);
+            let frames = vec![
+                make_node_frame(0, 100, 56, 1.0),
+                make_node_frame(1, 101, 56, 1.0),
+                make_node_frame(2, 102, 56, 1.0),
+            ];
+            let fused = fuser.fuse(&frames).expect("fuses");
+            assert_eq!(fused.node_positions[0], [0.0, 0.0, 0.0]);
+            assert_eq!(fused.node_positions[1], [1.0, 0.0, 0.0]);
+            assert_eq!(fused.node_positions[2], [2.0, 0.0, 0.0]);
+        }
+
+        /// Negative control: the pre-fix behaviour must actually be gone.
+        ///
+        /// Rank addressing over a dense zero-based config only diverges from
+        /// id addressing once the cohort is compacted, so this pins the exact
+        /// case the old code got wrong rather than restating the happy path.
+        #[test]
+        fn rank_addressing_would_have_failed_this_cohort() {
+            let configured = positions(&[
+                (0, [0.0, 0.0, 0.0]),
+                (1, [1.0, 0.0, 0.0]),
+                (2, [2.0, 0.0, 0.0]),
+            ]);
+            let mut fuser = MultistaticFuser::new();
+            fuser.set_node_positions_by_id(configured);
+
+            // Node 1 is silent; the cohort is [0, 2].
+            let frames = vec![
+                make_node_frame(0, 100, 56, 1.0),
+                make_node_frame(2, 101, 56, 1.0),
+            ];
+            let fused = fuser.fuse(&frames).expect("fuses");
+
+            // Rank addressing would hand rank 1 the position of node 1.
+            assert_ne!(fused.node_positions[1], [1.0, 0.0, 0.0]);
+            assert_eq!(fused.node_positions[1], [2.0, 0.0, 0.0]);
+        }
+    }
+
    #[test]
    fn geometric_diversity_single_node() {
        assert_eq!(geometric_diversity(&[[0.0, 0.0, 0.0]]), 0.0);
@@ -24,8 +24,8 @@
 //!
 //! macOS only. Gated behind `#[cfg(target_os = "macos")]` at the module level.

-use std::process::Command;
-use std::time::Instant;
+use std::process::{Command, Stdio};
+use std::time::{Duration, Instant};

 use crate::domain::bssid::{BandType, BssidId, BssidObservation, RadioType};
 use crate::error::WifiScanError;
@@ -64,11 +64,14 @@ impl MacosCoreWlanScanner {

    /// Run the Swift helper and parse the output synchronously.
    ///
-    /// Returns one [`BssidObservation`] per BSSID seen in the scan.
+    /// Returns one [`BssidObservation`] for the connected link.
+    /// Helpers that fail to exit within five seconds are killed and reaped.
    pub fn scan_sync(&self) -> Result<Vec<BssidObservation>, WifiScanError> {
-        let output = Command::new(&self.helper_path)
+        let mut child = Command::new(&self.helper_path)
            .arg("--scan-once")
-            .output()
+            .stdout(Stdio::piped())
+            .stderr(Stdio::piped())
+            .spawn()
            .map_err(|e| {
                WifiScanError::ProcessError(format!(
                    "failed to run mac_wifi helper ({}): {e}",
@@ -76,6 +79,29 @@ impl MacosCoreWlanScanner {
                ))
            })?;

+        // Older helpers ignore --scan-once and stream forever. Bound the
+        // wait so an outdated installation cannot hang capture or auto-detect.
+        let deadline = Instant::now() + Duration::from_secs(5);
+        loop {
+            match child.try_wait() {
+                Ok(Some(_)) => break,
+                Ok(None) if Instant::now() < deadline => {
+                    std::thread::sleep(Duration::from_millis(10));
+                }
+                status => {
+                    let _ = child.kill();
+                    let _ = child.wait();
+                    return Err(WifiScanError::ProcessError(match status {
+                        Err(e) => format!("failed to wait for mac_wifi: {e}"),
+                        _ => "mac_wifi --scan-once timed out; rebuild the Swift helper".into(),
+                    }));
+                }
+            }
+        }
+        let output = child.wait_with_output().map_err(|e| {
+            WifiScanError::ProcessError(format!("failed to read mac_wifi output: {e}"))
+        })?;
+
        if !output.status.success() {
            let stderr = String::from_utf8_lossy(&output.stderr);
            return Err(WifiScanError::ScanFailed {
@@ -160,7 +186,8 @@ fn parse_json_line(line: &str, timestamp: Instant) -> Option<BssidObservation> {
 /// Resolve a BSSID string to a [`BssidId`].
 ///
 /// If the MAC is all-zeros (macOS redaction), generate a synthetic
-/// locally-administered MAC from `SHA-256(ssid:channel)`.
+/// locally-administered MAC from the SSID and channel. Abstain when the
+/// real BSSID is unavailable and the SSID is blank.
 fn resolve_bssid(bssid_str: &str, ssid: &str, channel: u8) -> Option<BssidId> {
    // Try parsing the real BSSID first.
    if let Ok(id) = BssidId::parse(bssid_str) {
@@ -170,7 +197,13 @@ fn resolve_bssid(bssid_str: &str, ssid: &str, channel: u8) -> Option<BssidId> {
        }
    }

-    // Generate synthetic BSSID: SHA-256(ssid:channel), take first 6 bytes,
+    // Without either identity, unrelated networks on the same channel would
+    // collapse to one synthetic BSSID. Do not emit an observation in that case.
+    if ssid.trim().is_empty() {
+        return None;
+    }
+
+    // Generate synthetic BSSID from SSID and channel, take first 6 bytes,
    // set locally-administered + unicast bits (byte 0: bit 1 set, bit 0 clear).
    Some(synthetic_bssid(ssid, channel))
 }
@@ -276,6 +309,32 @@ mod tests {
 {"ssid":"Redacted","bssid":"00:00:00:00:00:00","rssi":-65,"noise":-88,"channel":149,"band":"5GHz"}
 "#;

+    #[test]
+    fn helper_process_errors_are_reported() {
+        assert!(matches!(
+            MacosCoreWlanScanner::with_path("/usr/bin/false").scan_sync(),
+            Err(WifiScanError::ScanFailed { .. })
+        ));
+        assert!(matches!(
+            MacosCoreWlanScanner::with_path("/dev/null/mac_wifi").scan_sync(),
+            Err(WifiScanError::ProcessError(_))
+        ));
+    }
+
+    #[test]
+    fn legacy_helper_is_timed_out() {
+        use std::os::unix::fs::PermissionsExt;
+        let path = std::env::temp_dir().join(format!("mac-wifi-timeout-{}", std::process::id()));
+        // exec preserves the helper PID, so killing it cannot orphan sleep.
+        std::fs::write(&path, "#!/bin/sh\nexec /bin/sleep 30\n").unwrap();
+        std::fs::set_permissions(&path, std::fs::Permissions::from_mode(0o700)).unwrap();
+        let start = Instant::now();
+        let result = MacosCoreWlanScanner::with_path(path.to_string_lossy()).scan_sync();
+        std::fs::remove_file(path).unwrap();
+        assert!(matches!(result, Err(WifiScanError::ProcessError(ref e)) if e.contains("timed out")));
+        assert!(start.elapsed() < Duration::from_secs(15));
+    }
+
    #[test]
    fn parse_valid_output() {
        let obs = parse_macos_scan_output(SAMPLE_OUTPUT).unwrap();
@@ -304,6 +363,29 @@ mod tests {
        assert_eq!(obs[2].bssid.0[0] & 0x01, 0x00);
    }

+    #[test]
+    fn unavailable_bssid_without_ssid_abstains() {
+        for bssid in ["00:00:00:00:00:00", "", "invalid"] {
+            for ssid in ["", "   "] {
+                let output = format!(
+                    r#"{{"ssid":"{ssid}","bssid":"{bssid}","rssi":-65,"noise":-88,"channel":36}}"#
+                );
+                assert!(parse_macos_scan_output(&output).unwrap().is_empty());
+            }
+        }
+    }
+
+    #[test]
+    fn real_bssid_without_ssid_is_preserved() {
+        let output = r#"{"ssid":"","bssid":"aa:bb:cc:dd:ee:ff","rssi":-65,"noise":-88,"channel":36}"#;
+        let obs = parse_macos_scan_output(output).unwrap();
+        assert_eq!(obs.len(), 1);
+        assert_eq!(obs[0].bssid.to_string(), "aa:bb:cc:dd:ee:ff");
+        assert!(obs[0].ssid.is_empty());
+        assert_eq!(obs[0].rssi_dbm, -65.0);
+        assert_eq!(obs[0].channel, 36);
+    }
+
    #[test]
    fn synthetic_bssid_is_deterministic() {
        let a = synthetic_bssid("TestNet", 36);
@@ -1 +1 @@
 .8.8
 .8.12