docs(firmware): document the tunables, and which ones depend on the house

The Kconfig options were discoverable only by opening menuconfig and reading
help text, which requires already knowing they exist. Two of them --
CSI_GATE_MESH_ALIGNED and the thermal throttle pair -- have no universally
right value: they depend on walls, transmitters, enclosure and placement.

Lists all eight with their defaults, marks which are house-dependent, and says
what to measure for each. Notes explicitly that in one measured fleet window
alignment bought +0.5 pp of cross-node pairing while rx_seq selection bought
+31.7 pp, so nobody inherits the assumption that the default is doing the work.

Co-Authored-By: claude-flow <ruv@ruv.net>
Claude-Session: https://claude.ai/code/session_01BHNNWbmKvxXrVaEDwXEBNo

firmware/esp32-csi-node/RUNBOOK.md

@@ -198,3 +198,54 @@ on 2026-09-03; the real answer, once it had settled, was −56 KiB.
 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.
+
+### 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.