open-bamboo-networking/research/08.08-print-abi.md

8.8. Submitting a print job

Studio starts a print or storage upload by filling a PrintParams and calling one of five bambu_network_start_* entry points. Typedefs and the struct live in bambu_networking.hpp / L199-250; Studio resolves the symbols via dlsym and wraps them in NetworkAgent::{start_print,…}. Progress / cancel / wait lambdas are per-call arguments — not agent-level setters (§8.2).

Neighbors: MQTT topics / sequence_id (§6.2); FTPS naming / probe (§8.8.6); Send-to-Printer ft_* (§8.14); :6000 wire (§6.4); signing / url_enc / HTTP PoP (§10.3 / §10.4 / §10.5); Studio-forwarded timelapse preflight (§12.11); HTTP hosts (§6.6).

Symbol	Signature	Notes
bambu_network_start_local_print	int(void*, PrintParams, OnUpdateStatusFn, WasCancelledFn)	Pure LAN print
bambu_network_start_local_print_with_record	int(void*, PrintParams, OnUpdateStatusFn, WasCancelledFn, OnWaitFn)	Hybrid / “LAN with cloud record”
bambu_network_start_print	int(void*, PrintParams, OnUpdateStatusFn, WasCancelledFn, OnWaitFn)	Pure cloud print
bambu_network_start_sdcard_print	int(void*, PrintParams, OnUpdateStatusFn, WasCancelledFn)	Print file already on printer storage
bambu_network_start_send_gcode_to_sdcard	int(void*, PrintParams, OnUpdateStatusFn, WasCancelledFn, OnWaitFn)	FTPS upload only; no MQTT print command

8.8.1. Common contract

Callback typedefs (bambu_networking.hpp:136-138):

using OnUpdateStatusFn = std::function<void(int status, int code, std::string msg)>;
using WasCancelledFn   = std::function<bool()>;
using OnWaitFn         = std::function<bool(int status, std::string job_info)>;

status is a SendingPrintJobStage value. OnWaitFn appears in the ABI for start_print, start_local_print_with_record, and start_send_gcode_to_sdcard; Studio uses it for the two cloud-facing print paths only.

SendingPrintJobStage (bambu_networking.hpp:153-163) — first argument of OnUpdateStatusFn / OnWaitFn. Unchanged across snapshots 02.03.00 … 02.08.01:

Value	Enumerator	Typical use
0	PrintingStageCreate	Job / cloud project create
1	PrintingStageUpload	Model / config body upload (FTPS, S3, :6000)
2	PrintingStageWaiting	Waiting on cloud / printer readiness
3	PrintingStageSending	MQTT / cloud dispatch in progress
4	PrintingStageRecord	Cloud history / record step
5	PrintingStageWaitPrinter	Waiting for printer ack / job_id
6	PrintingStageFinished	Success terminal (Studio expects code=0, msg = elapsed seconds string)
7	PrintingStageERROR	Failure terminal
8	PrintingStageLimit	Quota / rate-limit style failure

PrintParams (bambu_networking.hpp:199-250) — passed by value; field order and presence are part of the C++ ABI. MQTT mapping: project_file payload. Cloud REST bodies: Plugin behaviour of §8.8.3 / §8.8.4.

Since = first networking ABI series in tools/abi_snapshot/ where the member appears in bambu_networking.hpp (series gate is the first three version components, e.g. 02.05.03). Fields without a Since column were already present in the oldest snapshot (02.03.00). Adding a member changes sizeof(PrintParams) — a plugin built for an older series must not assume later fields exist.

Field	Type	Default	Since	Meaning
dev_id	std::string	—		Printer serial / device id
task_name	std::string	—		Human task label; also MQTT subtask_name fallback for pick_remote_name
project_name	std::string	—		Remote object / display name; FTPS STOR name for §8.8.6 ("verify_job" = write probe only)
preset_name	std::string	—		Process / filament preset label (cloud / history)
filename	std::string	—		Local path of the print-ready .3mf (or probe file)
config_filename	std::string	—		Local path of the small config/history .3mf (cloud paths)
plate_index	int	—		Plate number → MQTT param = Metadata/plate_N.gcode
ftp_folder	std::string	—		FTPS directory; Studio usually leaves empty (upload to root)
ftp_file	std::string	—		Optional remote FTPS object name override
ftp_file_md5	std::string	—		Unused by Studio — never assigned in PrintJob (same as ftp_file). Stock LAN MQTT ignores it (md5:"from_sd_card" even with a hex sentinel). Stock cloud PATCH profile_print_3mf[].md5 is the plugin's own uppercase-hex MD5 of filename, not this field (§8.8.3). Intended purpose unknown; the name suggests a precomputed FTPS-body hash, but no capture shows stock reading it.
nozzle_mapping	std::string	—		Nozzle index mapping string for multi-nozzle jobs
ams_mapping	std::string	—		Compact AMS slot list → MQTT ams_mapping JSON array
ams_mapping2	std::string	—		Structured AMS map → MQTT ams_mapping2
ams_mapping_info	std::string	—		Rich AMS detail JSON for cloud amsDetailMapping — not copied into LAN project_file
nozzles_info	std::string	—		Nozzle metadata JSON for cloud / diagnostics — not in LAN project_file
connection_type	std::string	—		Studio connection class (lan / cloud / …); gates which entry point is chosen
comments	std::string	—		Free-form comment for cloud task — not in LAN project_file
origin_profile_id	int	0		MakerWorld / cloud profile id
stl_design_id	int	0		MakerWorld design id
origin_model_id	std::string	—		Cloud / MakerWorld model id string
print_type	std::string	—		e.g. from_sdcard_view selects start_sdcard_print
dst_file	std::string	—		Path already on printer storage (file:/// / sdcard print)
dev_name	std::string	—		Display name of the printer
dev_ip	std::string	—		LAN IP (FTPS / :6000 / LAN MQTT)
use_ssl_for_ftp	bool	—		Prefer FTPS vs plain FTP
use_ssl_for_mqtt	bool	—		Prefer MQTTS vs plain MQTT on LAN
username	std::string	—		LAN login (normally bblp)
password	std::string	—		LAN access code
task_bed_leveling	bool	—		→ MQTT bed_leveling
task_flow_cali	bool	—		→ MQTT flow_cali
task_vibration_cali	bool	—		→ MQTT vibration_cali
task_layer_inspect	bool	—		→ MQTT layer_inspect
task_record_timelapse	bool	—		→ MQTT timelapse
task_timelapse_use_internal	bool	—	02.05.03	Timelapse to internal storage → MQTT cfg bit 0x4. Absent before this series ⇒ stock can never set that bit (but bit 0x1 is still reachable via task_ext_change_assist)
task_use_ams	bool	—		→ MQTT use_ams
task_bed_type	std::string	—		→ MQTT bed_type (e.g. textured_plate)
extra_options	std::string	—		Opaque Studio extras for cloud — not in LAN project_file
auto_bed_leveling	int	0		→ MQTT auto_bed_leveling
auto_flow_cali	int	0		→ MQTT extrude_cali_flag (0/1/2, not a pure bool)
auto_offset_cali	int	0		→ MQTT nozzle_offset_cali
extruder_cali_manual_mode	int	-1	02.04.00	→ MQTT extrude_cali_manual_mode only when != -1 (sentinel omits the wire field). Note MQTT spelling extrude_* vs ABI extruder_*
task_ext_change_assist	bool	—		External-spool change assist. No dedicated key anywhere: it is cfg bit 0 in both LAN project_file and POST /my/task (§8.8.8)
try_emmc_print	bool	—		Studio sets from could_emmc_print / brtc capability; does not alone select model transport (stock picks by entry point — table below). Not in LAN project_file
svc_context	std::string	—	02.07.01	Optional MakerWorld / model metadata (BBL_SVC_CONTEXT_TAG); Studio copies when present (PrintJob.cpp). → cloud svcContext only (see below)
slicer_uid	std::string	—	02.08.01	Slicer instance uid. Header-only in Studio 02.08.02.60 (no write site), but the plugin does forward it: → LAN MQTT slicer_uid only (see below)
queue_plate_id	std::string	—	02.08.02	Print Queue plate id, added alongside the unused PrintQueue* structs (§8.16.9). No Studio write site, but the plugin forwards it: → cloud plateId as a number (see below)

svc_context / slicer_uid / queue_plate_id on the wire. All three are forwarded by stock 02.08.02.54, each to exactly one destination and none to both. Measured by running the stock plugin under tools/plugin_runner with three parameter sets — one control with the fields unset, one with alphabetic sentinels, one with numeric sentinels — while watching LAN MQTT, cloud MQTT and HTTPS simultaneously (method in §8.8.7):

Field	LAN MQTT project_file	POST /my/task	Shape	Omitted when
slicer_uid	slicer_uid	—	string, verbatim	empty
queue_plate_id	—	plateId	number, strtoll of the string	empty, unparseable, or 0
svc_context	—	svcContext	string, verbatim	empty

Two details only the two-sentinel design could catch. queue_plate_id crosses the ABI as a std::string but lands on the wire as a JSON number, so the alphabetic sentinel silently became 0 and the key vanished — reading that as "not forwarded" is exactly the wrong conclusion, and the numeric set is what disproved it. Its value 9988776655 exceeds 32 bits, matching the int64_t plate ids in the PrintQueue* structs. Conversely slicer_uid and svc_context survive both sentinel sets byte-identically, so neither is parsed or normalised.

Both project_file capture paths agree: sdcard_print (no upload, md5:"from_sd_card", no url) and local_print (FTPS upload, url_enc) carry slicer_uid identically. start_local_print_with_record publishes no project_file at all — the cloud dispatches it — which is why the earlier record-print capture saw none of the three in MQTT.

The stock project_file serializer emits keys in alphabetical order (json_lite over a std::map), placing slicer_uid between sequence_id and subtask_id. Key order carries no meaning for the firmware (§10.4 — only byte-for-byte agreement between the signed string and the envelope matters), so our builder's own ordering stays as is.

Notable Studio values: project_name="verify_job" is only a probe filename (§8.8.6); print_type=="from_sdcard_view" sets dst_file and selects start_sdcard_print; ftp_folder is usually empty (stock uploads to FTPS root).

Return convention. int: 0 on success. Cancel when cancel_fn() is true → BAMBU_NETWORK_ERR_CANCELED (−18) (§8.16). Studio also treats other negatives / update_fn with stage==ERROR or code outside 0–100 as failure. Success UX expects update_fn(PrintingStageFinished, 0, "<seconds>") (stock uses "3").

Signing / field encryption for MQTT on non–Developer Mode firmware: §10.3 / §10.4. Cloud upload HTTPS PoP: §10.5.

Stock model transport by ABI entry point (wire-confirmed P2S, 2026-07). Studio sets try_emmc_print = could_emmc_print the same way for every print path; that flag alone does not select the model body transport — stock picks by entry point:

Entry	Cloud HTTPS	LAN model upload (stock)	Winning model URL / who prints
start_local_print	none	Full .3mf over TLS :6000 (brtc)	LAN MQTT project_file with brtc://emmc/<name> — only honest LAN path
start_local_print_with_record	Config + full .3mf to S3; two project PATCHes (ftp:// then https S3)	Full .3mf over FTPS :990 only (never brtc)	Cloud /my/task mode=lan_file → printer re-downloads S3
start_print	Config + full .3mf to S3; PATCH → S3	none	Cloud /my/task mode=cloud_file → S3 download

MQTT project_file payload

Used by start_local_print and start_sdcard_print (plugin builds the frame). Cloud /my/task paths must not also publish this command on the same start. Topics / sequence_id assignment: §6.2.

The print-job submission ends with a single MQTT command published to the printer's request channel (device/<dev_id>/request on LAN, identical envelope on the cloud forwarder). The frame the firmware actually parses lives under the print object. The example below was captured on a real P2S running stock firmware paired with the stock Studio + plugin; X1 / P1S share the schema with a few extra optional members.

{
  "print": {
    "sequence_id":             "20001",
    "command":                 "project_file",
    "param":                   "Metadata/plate_1.gcode",
    "project_id":              "0",
    "profile_id":              "0",
    "task_id":                 "0",
    "subtask_id":              "0",
    "subtask_name":            "test",
    "file":                    "test.gcode.3mf",
    "url_enc":                 "bcXiq4/uHGqgb4DXVihrpQOR…",
    "md5":                     "from_sd_card",
    "bed_type":                "textured_plate",
    "bed_leveling":            false,
    "flow_cali":               false,
    "vibration_cali":          false,
    "layer_inspect":           true,
    "timelapse":               true,
    "use_ams":                 true,
    "ams_mapping":             [3,-1,-1],
    "ams_mapping2":            [{"ams_id":0,"slot_id":3},{"ams_id":255,"slot_id":255},{"ams_id":255,"slot_id":255}],
    "auto_bed_leveling":       0,
    "cfg":                     "4",
    "extrude_cali_flag":       0,
    "extrude_cali_manual_mode":0,
    "nozzle_offset_cali":      2
  }
}

Field	Type	Source in PrintParams (Studio -> ABI)	Notes
sequence_id	string (decimal)	See §6.2	Stock plugin always emits "20001" for project_file on a fresh process (every ABI 02.05.00–02.08.02). Reusing that value across restarts yields err_code 84033544. We seed randomly in 20000–29999 and increment. See the 84033544 readings block in §10.04.
command	string	constant "project_file"	Selects the firmware handler.
param	string	derived from plate_index	Always Metadata/plate_<N>.gcode; resolves to a path inside the uploaded 3mf.
project_id, profile_id, task_id, subtask_id	strings	cloud task IDs from POST /v1/user-service/my/task (cloud) or "0" placeholder (LAN / Developer Mode)	Sent as strings, not numbers.
subtask_name	string	project_name (falls back to task_name)	Shown on the printer screen.
file	string	project_name / task_name via pick_remote_name	Basename of the .3mf. Stock ignores dst_file even on sdcard_print (a probe with dst_file="cache/obn-nonexistent-L1.gcode.3mf" still published file:"obn-probe-L1.gcode.3mf"). On local_print it matches the uploaded FTPS/brtc name.
url / url_enc	string	opts.url	Tells firmware how to locate the .3mf on local_print. sdcard_print omits both keys (stock 02.05.00–02.08.02) — firmware looks the file up by file + md5:"from_sd_card". Cleartext url uses one of several schemes (ftp://, brtc://emmc/, file://, presigned https://… for cloud); url_enc is the same URL RSA-encrypted with the printer's device-cert public key using PKCS#1 v1.5 padding (direct RSA, no AES session-key wrap — the observed ≤~245-byte ciphertext equals the RSA-2048 PKCS#1 v1.5 ceiling of 256−11=245 and rules out OAEP-SHA1, which would cap at 214; independently cross-validated in issue #47, on-wire confirmation of the padding still pending). Non-Developer-Mode firmware requires url_enc; Developer Mode accepts plain url. Full scheme semantics: see URL schemes below.
md5	string	literal "from_sd_card"	Stock 02.05.00–02.08.02 always emit this literal — on sdcard_print and on FTPS local_print, even when ftp_file_md5 is filled with a hex sentinel (Studio never assigns that field). A real file hash never appeared in any captured LAN project_file. Cloud PATCH uses a different md5 — see §8.8.3. Beyond stock, the value is a 3-way semantics split: ours = literal "from_sd_card" (kept as-is, this row); beambam = uppercase md5 of the inner Metadata/plate_N.gcode; Doridian #72 = whole-.3mf md5 — wrong value → 0x0500403F / 83902527 or 84033544. Source: community-survey cross-check #4
bed_type	string	task_bed_type (defaults to "auto")	One of the MachineBedTypeString values.
bed_leveling, flow_cali, vibration_cali, layer_inspect, timelapse, use_ams	bool	matching task_* flags	Per-print toggles from the SelectMachineDialog checkboxes.
ams_mapping	int array	ams_mapping (Studio passes a JSON array string [0,-1,...])	Index = filament slot in the 3mf, value = AMS tray id (-1 = no mapping, 255 = virtual tray). Legacy single-AMS shape. Empty string → [] even with use_ams=true (stock 02.05.03 / 02.08.02); there is no [0] fallback.
ams_mapping2	object array	ams_mapping2 (Studio passes a JSON-array string of {ams_id, slot_id} objects)	Newer multi-AMS schema, one entry per filament. 255/255 means "external spool / not via AMS". Required for printers with >1 AMS unit; firmware that supports both fields prefers ams_mapping2 over ams_mapping. Note: cloud POST /my/task uses a different AMS serialization — the plugin re-keys the pairs to camelCase and drops the keys altogether when the mapping is empty, whereas project_file always carries both as [] (§8.8.8).
nozzle_mapping	int array	nozzle_mapping (Studio passes a JSON-array string of ints, e.g. "[0,1]")	Index = filament slot in the 3mf, value = physical nozzle/extruder position id. Emitted only on multi-extruder printers — Studio gates every assignment to task_nozzle_mapping on MachineObject::GetNozzleRack()->IsSupported() (see SelectMachine.cpp:3107 and CalibUtils.cpp:2225/2358), so on single-nozzle hardware (P2S, X1C, A1, etc.) the field is omitted entirely from project_file. The Studio-side value is sourced verbatim from the printer's reply to the get_auto_nozzle_mapping MQTT query (DevMappingNozzle.cpp:277-282 deserialises the mapping field into std::vector<int>), so the type is always a flat int array — no objects, no string-wrapped numbers, no [0,-1,…] sentinels analogous to ams_mapping. Stock-plugin observation: when Studio hands it a string with whitespace (e.g. "[0,1, 2]"), the stock plugin re-emits it as canonical "[0,1,2]"; this normalization is cosmetic and not required for firmware acceptance.
auto_bed_leveling	int	auto_bed_leveling	Bed-leveling option as an int (0 = off, 1 = on, 2 = auto). Coexists with the boolean bed_leveling: the boolean is the user toggle, the int is the resolved policy after taking firmware capabilities into account.
nozzle_offset_cali	int	auto_offset_cali (name mismatch is intentional in upstream)	Nozzle-offset calibration option (0 = off, 2 = auto).
extrude_cali_manual_mode	int	extruder_cali_manual_mode (extrude vs extruder asymmetry is intentional in upstream)	PA calibration mode (0 = automatic, 1 = manual). Field is gated on the value, not the ABI — the stock plugin emits it only when extruder_cali_manual_mode != -1 (the PrintParams default). With the default sentinel it is omitted entirely from project_file. Confirmed across ABI 02.05.00, 02.05.03, 02.06.01.
cfg	string (decimal int)	derived from task_ext_change_assist and task_timelapse_use_internal	Bitmask the stock plugin builds from PrintParams flags that don't have a dedicated MQTT field, and it is the same bitmask the plugin puts in POST /my/task (§8.8.8). Bit 0 (0x1) = task_ext_change_assist (sdcard_print with that flag alone published cfg:"1"). Bit 2 (0x4) = use internal storage for timelapse, driven by task_timelapse_use_internal. Both set gives "5". Bit 1 (0x2) has never been seen and no field this ABI exposes moves it (try_emmc_print included). Always emitted as a string, not a number. Field is present in project_file for every observed ABI from 02.05.00 upwards — but on builds older than 02.05.03 (where PrintParams::task_timelapse_use_internal does not exist yet) bit 0x4 is unreachable. Cross-ABI confirmation: 02.05.00/02.05.01/02.05.02 emit cfg="0" for a timelapse job; 02.05.03/02.06.00/02.06.01 emit cfg="4" when task_timelapse_use_internal=true. task_record_timelapse does NOT influence cfg — only the timelapse boolean in the same payload.
extrude_cali_flag	int	derived from auto_flow_cali	Stock-plugin-only field present in every observed project_file. The value is taken straight from PrintParams::auto_flow_cali and is a multi-valued enum, not a bool: 0 = off, 1 = requested, and 2 (= auto) has been observed in genuine traffic (issue #48); further values may exist. Captured Studio sessions almost always ship auto_flow_cali=0, which is why the field looks hardcoded at first glance. Likely a "PA cali requested" guard the firmware uses to short-circuit redundant calibration runs.

Cloud-start extras in project_file

The cloud variant of project_file is published by the cloud, not the plugin — start_local_print_with_record / start_print never put this frame on LAN MQTT. Captured on P2S after /my/task mode=lan_file (stock 02.08.02.54, 2026-08-16), the dispatched command carries extra keys the LAN builder does not emit:

• job_id — int (unlike task_id/subtask_id, which are strings), echoing the id minted by POST /v1/user-service/my/task;
• job_type: 1 — constant in observed cloud starts;
• design_id — MakerWorld design id (0 when the model is not from the store);
• model_id — the US… id from the project upload;
• dev_id — printer serial;
• plate_idx — plate index (cloud name; LAN uses param instead);
• bed_temp — instead of bed_type (the LAN key is absent);
• skip_objects — array, empty in the captures;
• timestamp — cloud-side unix time;
• extrude_cali_manual_mode — present even when the LAN plugin would have omitted the -1 default;
• no file, no slicer_uid.

A trailing "reason":"success","result":"success" pair appears on some published cloud commands, not only on the printer's ack. The plugin does not need to emit any of this — the cloud does.

URL schemes for model location (file / url)

The MQTT command is always project_file; there is no separate storage: emmc|udisk field that selects where the model lives. Instead, firmware interprets the url prefix (and the matching file basename/path). Observed / reverse-engineered on P2S (May 2026):

URL prefix	Example	Firmware behaviour (inferred)
ftp://	ftp://skadis_spool-Body.gcode.3mf	FTPS / sdcard-style volume, and one of the two URL schemes cloud dispatch appears to accept (with https://). Stock _with_record briefly PATCHes this, then overwrites with S3 https (§8.8.3). Older N7-class pure-LAN FTPS legs use it for real. A :6000 cache file of the same name does not satisfy ftp://.
ftp:/// (three slashes)	ftp:///skadis_spool-Body.gcode.3mf	Offline / pre-pushed variant of the row above, not a defect. Genuine traffic shows both spellings and they are scenario-dependent: two slashes when the plugin has just FTPS-uploaded the file, three slashes (empty authority = "local", absolute path) when the file was pushed to the printer earlier and the job starts offline against the already-present copy. Firmware accepts both. Cross-validated in issue #48.
brtc://emmc/	brtc://emmc/skadis_spool-Body.gcode.3mf	LAN MQTT model-cache lookup after :6000 cmdtype=5. Stock P2S start_local_print and Send-to-Printer use this. Not used on stock _with_record / start_print; cloud /my/task path shows no support for registering or dispatching brtc:// (§8.8.3). Despite the emmc token, firmware searches udisk cache then emmc (§6.4).
file://	file:///media/usb0/cache/skadis_spool-Body.gcode.3mf	Explicit filesystem path. No cache heuristics — open exactly that file. Typical for Print from Device when the .3mf is already on storage. Paths observed under /media/usb0/ with or without a /cache/ segment (e.g. file:///media/usb0/skadis_spool-Body.gcode.3mf).
https://	presigned object URL	Cloud print. Printer downloads from Bambu object storage; unrelated to local emmc/udisk caches.

Upload vs print-start: choosing Cache vs External in Send to Printer sets dest_storage ("emmc" / "udisk") in the :6000 cmdtype=5 upload (§6.4 / §8.14) — that decides where the file is written in the model cache. The url scheme at print-start decides how firmware finds the file afterward (brtc://emmc/ = search both caches; ftp:// = FTPS volume; file:// = fixed path). Hybrid stock print writes via FTPS and starts with ftp:// — not via the Send-to-Printer cache path (§8.8.3).

Not model storage: the cfg bitmask ("4" when task_timelapse_use_internal=true) and the ipcam_get_media_info preflight (§12.11) govern timelapse video recording destination, not which .3mf is printed.

Sibling header object the stock plugin wraps the command in (cloud and LAN alike when paired against signature-checking firmware):

Field encryption (url_enc): §10.3. MQTT signing: §10.4. HTTP PoP: §10.5. Trust / provisioning: §10.2. App-cert fetch: §10.2.

Cross-ABI project_file reverse-engineering matrix

The mapping above was verified by loading the stock libbambu_networking.so of each version below into a BBL::PrintParams-driven harness and capturing the resulting LAN MQTT project_file payload against an N7 in Developer Mode:

ABI tag	Plugin file	cfg baseline behaviour	New schema field(s) vs the prior tag
02.05.00	02.05.00.56	always "0"	(reference)
02.05.01	02.05.01.52	always "0"	none
02.05.02	02.05.02.58	always "0"	none
02.05.03	02.05.03.63	"4" if task_timelapse_use_internal=true, else "0"	cfg becomes settable (the PrintParams::task_timelapse_use_internal ABI break)
02.06.00	02.06.00.50	same as 02.05.03	none in project_file; only new exports are filament-spool CRUD (bambu_network_get_filament_spools, bambu_network_create_filament_spool, bambu_network_update_filament_spool, bambu_network_delete_filament_spools, bambu_network_get_filament_config) — those are HTTP plumbing, not LAN MQTT
02.06.01	02.06.01.50	same as 02.05.03	none

Bottom line: the on-the-wire project_file schema is essentially frozen across 02.05.x -> 02.06.x. The only ABI-significant change for LAN print submission is the addition of task_timelapse_use_internal in 02.05.03, which feeds the cfg bitmask (and only bit 0x4 has been observed so far). All field mappings below were also confirmed identical between 02.05.00 and 02.06.01 — only the cfg value differs between the two ABI families.

Per-PrintParams-field mapping (overlay matrix on ABI 02.05.03)

The following matrix was collected by toggling one PrintParams field at a time before handing the struct to the stock plugin and diffing the resulting project_file against an all-defaults baseline. It confirms — and in some cases corrects — the per-row notes in the table above.

PrintParams field overridden	Resulting project_file change
task_use_ams=true, ams_mapping="[0]", ams_mapping2='[{"ams_id":0,"slot_id":0}]'	use_ams: false → true, ams_mapping: [] → [0], ams_mapping2: [] → [{"ams_id":0,"slot_id":0}]
task_use_ams=true with empty ams_mapping / ams_mapping2	use_ams: true, both arrays stay [] — no [0] fallback (stock 02.05.03 / 02.08.02)
task_record_timelapse=false (and task_timelapse_use_internal=false)	timelapse: true → false, cfg: "4" → "0"
task_timelapse_use_internal=false (alone)	cfg: "4" → "0" (the timelapse boolean stays true)
task_bed_type="textured_plate"	bed_type: "auto" → "textured_plate"
task_bed_type="supertack_plate"	bed_type: "auto" → "supertack_plate"
task_bed_leveling=false, task_flow_cali=false, task_vibration_cali=false, task_layer_inspect=false	All four matching booleans flip to false (bed_leveling, flow_cali, vibration_cali, layer_inspect) — direct one-to-one mapping
extruder_cali_manual_mode=0	extrude_cali_manual_mode appears with value 0 (absent in baseline because -1 is the default)
extruder_cali_manual_mode=1	extrude_cali_manual_mode appears with value 1
auto_offset_cali=2	nozzle_offset_cali: 0 → 2 (note the upstream rename)
auto_bed_leveling=2	auto_bed_leveling: 0 → 2 (coexists with the bed_leveling boolean)
auto_flow_cali=1	extrude_cali_flag: 0 → 1 (this is how the previously mysterious extrude_cali_flag is populated)
project_name="my-print"	subtask_name, file, and url all switch in lock-step (<project_name>, <project_name>.gcode.3mf, ftp://<project_name>.gcode.3mf) — the FTP upload path follows suit
plate_index=2	param: "Metadata/plate_1.gcode" → "Metadata/plate_2.gcode"

Fields that did not appear on this hardware (P2S/N7 single-extruder) regardless of overrides: nozzle_mapping (gated on multi-extruder, see the dedicated row above), url_enc (Developer Mode bypasses the encrypted-URL requirement), and the entire header envelope (Developer Mode disables signature verification — see §10.4).

Studio call selection (bonus — does not change the plugin ABI)

Studio chooses which bambu_network_start_* symbol to call. The plugin implements each symbol independently; it does not re-run this tree.

UI → worker. Slice→Print / Device→Files→Print → PrintJob. Send to Printer → ft_* when is_support_brtc (§8.14), else rare SendJob → start_send_gcode_to_sdcard. Access-code probe → start_send_gcode_to_sdcard with project_name="verify_job" (§8.8.6). Capability bitmaps that gate UI: §12.1.

PrintJob::process() decision tree (PrintJob.cpp:149-624):

flowchart TD
  subgraph pre [Preflight — LAN normal print only]
    A["connection_type==lan && from_normal"] --> B["FileTransferTunnel :6000 sync_connect\n(could_emmc_print)"]
    A --> C["start_send_gcode_to_sdcard\nproject_name=verify_job"]
    B --> D{emmc_ok OR ftp_ok?}
    C --> D
    D -->|no| E["abort: invalid access code"]
  end
  D -->|yes| F{m_print_type?}
  F -->|from_sdcard_view| G["start_sdcard_print"]
  F -->|from_normal| H{connection_type?}
  H -->|lan| I{has_sdcard OR could_emmc_print?}
  I -->|yes| J["start_local_print"]
  I -->|no| K["abort: no storage"]
  H -->|cloud / farm| L{lan_mode_only?}
  L -->|yes| M["start_local_print_with_record"]
  L -->|no| N{IP+password+has_sdcard?}
  N -->|yes| O["start_local_print_with_record"]
  O -->|fail| P["start_print — cloud fallback"]
  N -->|no| P

connection_type is the printer’s mode advertisement (SSDP devconnect.bambu.com → connect_type), not “LAN reachable”: "lan" → start_local_print; "cloud" → prefer _with_record when IP+code+storage exist, else start_print; "farm" treated like LAN for path selection.

Before PrintJob (no print ABI): export plate .3mf; export config .3mf for non-LAN; AMS/nozzle MQTT queries into PrintParams; optional timelapse storage check via send_message* (§12.11).

Callback UX Studio expects (PrintJob.cpp:405-548): update_fn drives the progress bar (Create=20% … Finished=100%; Upload/Record sub-percent from code 0–100). wait_fn is used only for start_print / _with_record (poll job_id / print status). Pure LAN navigates away on Finished alone. Ongoing telemetry after submit uses push_status / other ABIs — not start_*.

LAN MQTT for project_file is on an already-connected session (connect_printer is outside PrintJob). A cloud-paired printer may still have a live LAN session (§6.2, §10.6).

8.8.2. bambu_network_start_local_print

Parameters.

Name	Type	Meaning
agent	void*	Opaque agent from create_agent.
params	PrintParams	Job description (by value); LAN credentials + local filename.
update_fn	OnUpdateStatusFn	Progress / stage callback (SendingPrintJobStage).
cancel_fn	WasCancelledFn	Poll for user cancel; abort with BAMBU_NETWORK_ERR_CANCELED.

Purpose. Start a pure LAN print: deliver the plate .3mf to the printer over the LAN channel and publish MQTT project_file. No cloud /my/task.

Studio. PrintJob when connection_type=="lan" and print_type=="from_normal", after LAN preflight (Studio call selection). Wrappers: NetworkAgent.cpp:1185-1190. No OnWaitFn in the ABI.

Plugin behaviour. On an already-connected LAN MQTT session (connect_printer is outside this call):

1. Upload the full print-ready .3mf on LAN. Stock on P2S (wire-confirmed): TLS :6000 / brtc (cmd_type=5), then MQTT URL brtc://emmc/<name>. Older N7-class path: FTPS :990 + ftp://. See transport table.
2. Publish MQTT project_file with "0" cloud id placeholders and the chosen URL scheme — payload. sequence_id: §6.2.
3. Drive update_fn through Upload → Sending → Finished; honor cancel_fn.

Do not call POST /my/task. Do not dual-start via cloud MQTT project_file after a cloud path.

Return. 0 on success; negative on failure / cancel.

8.8.3. bambu_network_start_local_print_with_record

Parameters.

Name	Type	Meaning
agent	void*	Opaque agent from create_agent.
params	PrintParams	Job description; typically cloud-typed device with LAN IP/code present.
update_fn	OnUpdateStatusFn	Progress / stage callback.
cancel_fn	WasCancelledFn	Cancel poll.
wait_fn	OnWaitFn	After task create, wait for printer job_id / status.

Purpose. Hybrid / “LAN with cloud record” print path for cloud-paired printers when Studio has LAN credentials and storage.

Studio. PrintJob cloud/farm branch when IP + password + storage (or lan_mode_only) — Studio call selection. On return < 0, Studio may call start_print as its own fallback. Wrappers: NetworkAgent.cpp:1170-1176.

Plugin behaviour. Despite the name, stock is not an honest LAN-only print (P2S, Studio/plugin ~02.08; also 02.04 — MITM + LAN pcap, 2026-07): the printer re-downloads from S3 after /my/task. Observed order:

1. POST /v1/iot-service/api/user/project {"name":"<job>"} → project_id, model_id, profile_id, first presigned upload_url, upload_ticket.
2. PUT <upload_url> — small config/profile .3mf (export_config_3mf). Omit Content-Type on presigned PUTs (presigner signs empty Content-Type; adding one → 403 SignatureDoesNotMatch). Print-upload URLs are S3 SigV2 query-auth; the cloud presigns — client does not recompute the signature.
3. PUT /v1/iot-service/api/user/notification + poll GET …/notification?action=upload&ticket=… until success.
4. LAN FTPS :990 — full print-ready .3mf STOR (stock never uses :6000/brtc on this ABI).
5. PATCH …/user/project/<pid> — first register, e.g. {"profile_id":"…","profile_print_3mf":[{"md5":"55705660B4D0360DB2CE5D399D3B4DD0","plate_idx":1,"url":"ftp://….gcode.3mf"}]}. md5 is 32 uppercase hex of the print-ready .3mf (filename); stock computes it in-plugin. Not PrintParams.ftp_file_md5 (Studio leaves that empty). Cloud accepts an all-zero placeholder (200) but stock never sends one (stock_hybrid.mitm / stock_hybrid_2.4.0.mitm / stock_block_cloud.mitm, 2026-07).
6. GET /v1/iot-service/api/user/upload?models=<model_id>_<profile_id>_<plate>.3mf → second presigned URL.
7. PUT <second URL> — full .3mf to S3 again (same Content-Type rule).
8. PATCH …/user/project/<pid> — second register with https S3 URL (wins; early ftp:// PATCH has no lasting effect).
9. POST /v1/user-service/my/task with mode":"lan_file" — cloud dispatches; printer re-downloads S3.

/my/task authorization. Beyond Authorization: Bearer: mandatory X-BBL-Client-Name: BambuStudio + matching X-BBL-OS-Type (§6.6); for secured printers also x-bbl-app-certification-id / x-bbl-device-security-sign (§10.5). Treat non-2xx as fatal (do not continue with task_id=0).

amsDetailMapping[] element (amsMapping/amsMapping2 are camelCase and optional, external-spool sentinel {amsId:255,slotId:0} — issue #48, full key-by-key gating in §8.8.8):

{
  "ams": 0,
  "filamentId": "GFA00",
  "filamentType": "PLA",
  "nozzleId": 0,
  "sourceColor": "#FFFFFFFF",
  "targetColor": "#FFFFFFFF"
}

Colors are RGBA hex with leading #. Source data: PrintParams::ams_mapping_info.

Do not publish LAN MQTT project_file for the start (duplicate job → 0500_4004). Preserve exactly one /my/task per user action — if this entry point creates the cloud task, return 0; failing after /my/task triggers Studio’s start_print fallback and a second task. Cloud-dispatched project URLs appear limited to https://… and ftp://… (not brtc://). Skipping the small config upload still starts the print but leaves Print History without a thumbnail — stock always does step 2–3.

Return. 0 on success; negative on failure / cancel. Studio may fall back to start_print when < 0.

8.8.4. bambu_network_start_print

Parameters.

Name	Type	Meaning
agent	void*	Opaque agent from create_agent.
params	PrintParams	Job description; includes config_filename for the small history/preview .3mf.
update_fn	OnUpdateStatusFn	Progress / stage callback.
cancel_fn	WasCancelledFn	Cancel poll.
wait_fn	OnWaitFn	Wait for cloud-dispatched job / printer status.

Purpose. Pure cloud print: upload to Bambu object storage and let the cloud dispatch the job to the printer.

Studio. When LAN prerequisites are missing, cloud_print_only is set, or as fallback after _with_record fails (Studio call selection). Wrappers: NetworkAgent.cpp:1158-1164.

Plugin behaviour. Same shape as §8.8.3 steps 1–3 and 6–9, without FTPS / ftp:// PATCH (skip hybrid steps 4–5). Final POST /my/task uses mode":"cloud_file". Same S3 Content-Type rule, /my/task headers, amsDetailMapping schema, and hard-fail on non-2xx. No LAN model upload and no plugin MQTT project_file (cloud dispatch is the trigger; publishing project_file double-fires).

Return. 0 on success; negative on failure / cancel.

8.8.5. bambu_network_start_sdcard_print

Parameters.

Name	Type	Meaning
agent	void*	Opaque agent from create_agent.
params	PrintParams	Must carry dst_file (path on printer); print_type is from_sdcard_view.
update_fn	OnUpdateStatusFn	Progress / stage callback.
cancel_fn	WasCancelledFn	Cancel poll.

Purpose. Start printing a .3mf that is already on printer storage (Device → Files → Print). No model upload.

Studio. PrintJob when print_type=="from_sdcard_view"; sets dst_file instead of a local filename (Studio call selection). Wrappers: NetworkAgent.cpp:1192-1195. No OnWaitFn.

Plugin behaviour. Publish MQTT project_file with url=file:///<dst_file> (and the usual plate/AMS flags) on the active session — payload. No FTPS/S3 body upload for the model.

TODO: need capture of stock start_sdcard_print under MITM / MQTT — confirm whether stock also hits a signed cloud REST endpoint, or only MQTT project_file with file:///.

Return. 0 on success; negative on failure / cancel.

8.8.6. bambu_network_start_send_gcode_to_sdcard

Parameters.

Name	Type	Meaning
agent	void*	Opaque agent from create_agent.
params	PrintParams	Local filename to upload; remote object name = sanitized project_name.
update_fn	OnUpdateStatusFn	Progress (often nullptr for verify_job probe).
cancel_fn	WasCancelledFn	Cancel poll.
wait_fn	OnWaitFn	Present in the ABI; Studio upload/probe paths typically do not use it like cloud print.

Purpose. FTPS upload of a local file to printer storage. Does not start a print (no MQTT project_file). Session ends after STOR (+ QUIT in observed stock flows).

Studio. LAN access-code / write probe with project_name="verify_job"; rare Send-to-Printer fallback when !is_support_brtc (Studio call selection). On P2S / brtc hardware, Send to Printer model bytes use ft_* / :6000 (§8.14), not this ABI. Wrappers: NetworkAgent.cpp:1178-1183.

Caller	project_name	Notes
PrintJob::process() — LAN normal print preflight	"verify_job"	Tiny resources/check_access_code.txt; then start_local_print (PrintJob.cpp:236-240)
SendJob::process() — check mode	"verify_job"	IP / access-code dialog; returns after probe (SendJob.cpp:134-148, ReleaseNote.cpp:1994)
SendJob via SendToPrinterDialog else branch	<project>.gcode.3mf	When !is_support_brtc — full model over FTPS (SendToPrinter.cpp:977-1027)

Studio today passes m_project_name + ".gcode.3mf" for SendJob uploads (SendJob.cpp:206, since 46dc96fd 2022-11); bare names on this ABI are mainly historical or headless callers.

Plugin behaviour. Upload params.filename over FTPS; the object name on the printer is sanitized project_name — no automatic .gcode.3mf suffix. Do not reuse pick_remote_name (that helper is for start_local_print / cloud FTPS legs / MQTT file / url). "verify_job" is not magic — only the filename Studio chose for the write-access probe. Progress via update_fn(PrintingStageUpload, 0-100, …) when callbacks are provided.

Stock naming (probe via tools/probe_remote_naming.sh / tools/plugin_runner.sh against cached libbambu_networking.so ABIs 02.05.03 and 02.06.01, May 2026; then curl FTPS LIST):

PrintParams.project_name	Stock STOR name (send_gcode_to_sdcard)	Stock start_local_print MQTT file / url
"verify_job"	verify_job	—
"obn_probe_bare" (bare)	obn_probe_bare (no suffix)	—
"obn_probe_bare.gcode.3mf"	obn_probe_bare.gcode.3mf	—
"" (empty, task_name set)	ERROR -5010 (URL without a file name)	—
"obn_print_bare" (bare)	—	obn_print_bare.gcode.3mf / ftp://obn_print_bare.gcode.3mf; subtask_name = bare

Hermetic naming logic (no printer): tests/remote_name_test.cpp — ctest -R remote_name with -DOBN_BUILD_TESTS=ON.

pick_remote_name (print upload + MQTT file / url — not this ABI). Used by start_local_print, start_local_print_with_record, and the cloud FTPS leg. Stock behaviour on N7, May 2026:

Input	Output STOR / MQTT file	MQTT subtask_name
project_name="my-print"	my-print.gcode.3mf	my-print
project_name="", task_name="task"	task.gcode.3mf	task
project_name="foo.gcode.3mf"	foo.gcode.3mf (no double suffix)	foo.gcode.3mf
both empty, filename="/path/x.gcode.3mf"	x.gcode.3mf	(from task_name, often empty)
all empty	print.gcode.3mf	—

Evolution (BambuStudio git history):

When	Commit (approx.)	Change
2023-02	a94b78d29 add network verification process for LAN printing	verify_job probe added to PrintJob / SendJob preflight — still this ABI + FTPS
2024-10	0ec49c358 Support direct connection to LAN printers	LAN IP dialog reuses SendJob check mode with the same probe
2025-10	76e45bde2 print with emmc + 662b7fdac change send mode	ft_* :6000 cache upload when MachineObject::is_support_brtc (print.fun bit 31); SendToPrinter prefers TCP/TUTK tunnel + CreateUploadFileJob; FTPS SendJob path kept as else fallback — see Studio call selection / §12.1

So FTPS via this ABI predates the :6000 / brtc path; the newer upload transport is ft_* (§8.14 / §6.4), not a different reading of the same ABI.

Observed FTPS transcript — write probe (project_name="verify_job", P2S):

220 (vsFTPd 3.0.5)
USER bblp
331 Please specify the password.
PASS <access_code>
230 Login successful.
PBSZ 0
200 PBSZ set to 0.
PROT P
200 PROT now Private.
PWD
257 "/" is the current directory
EPSV
229 Entering Extended Passive Mode (|||50077|)
TYPE I
200 Switching to Binary mode.
STOR verify_job
150 Ok to send data.          ← external storage writable; probe continues on data channel
… tiny payload …
226 Transfer complete.
QUIT
221 Goodbye.

When external storage is absent or not writable, STOR verify_job fails (no 150 Ok to send data.). Stock Studio treats that as "no external target" and does not attempt the follow-up test upload on the passive data port. Either way, QUIT follows and FTPS is done for this job.

LAN port ordering (P2S, stock, Send + print with external USB — May 2026 tcpdump, not in-repo):

:6000  (session A) — early tunnel traffic (ability / setup)
:6000  (session B) — may overlap with UI prep
:990   (~0.7 s)     — FTPS verify_job STOR + QUIT only (~19 packets total)
:6000  (session C) — ft_* cmd_type=5 chunked .3mf upload (bulk ~262 KiB frames)
:6000  (session D) — further ft_* / tunnel work
MQTT :8883          — project_file / print start (outside this ABI)

Packet counts from that session: 19 on :990, 220 on :6000. FTPS is a short side trip, not the upload transport for brtc Send-to-Printer — do not STOR the full .3mf on :990 when :6000 works.

Tools.

Tool	Role
tools/probe_remote_naming.sh	Matrix of project_name → stock/open STOR name
tools/plugin_runner.sh	Drive print ABIs with JSON PrintParams against cached .so
tools/bambu_ftp_proxy.py	Plain FTP ↔ printer FTPS bridge
SSLKEYLOGFILE + Wireshark	Decrypt FTPS control/data on :990

Return. 0 on success; negative on failure / cancel (e.g. -5010 for empty project_name).

8.8.7. Sentinel probing PrintParams fields

Method used to settle slicer_uid / queue_plate_id / svc_context above; it generalises to any PrintParams field whose destination is unclear.

Put an implausible, greppable value in the field, run the stock plugin, and search every wire the job touches for it. Always use two sentinel sets — one alphabetic and one all-digits — plus a control set with the fields unset. A field that becomes a JSON number on the wire turns an alphabetic sentinel into 0, which typically gets dropped, and reads exactly like "not forwarded"; only the numeric set tells those two apart. That is precisely what happened with queue_plate_id.

Three capture points, all running at once, because a field may take any one of them:

Point	Tool	Sees
LAN MQTT	MQTT client subscribed to # on <printer>:8883 (user bblp, password = LAN access code, TLS verification off)	device/<SN>/request — what the plugin publishes, and report replies
HTTPS	mitmdump -s dump.py -p 8888, driving the runner with HTTPS_PROXY + CURL_CA_BUNDLE + SSL_CERT_FILE pointed at ~/.mitmproxy/mitmproxy-ca-cert.pem	POST /my/task and the whole record path
Cloud MQTT	same client against <region>.mqtt.bambulab.com:8883, user u_<user_id>, password = access token	what the cloud dispatches back to the printer

Drive it with tools/plugin_runner.sh --abi 02.08.02. Four flags matter and each has a failure mode that looks like something else:

• --cert-lan-only 0 on a cloud-paired printer. Otherwise the plugin never gets a device certificate, refuses every privileged publish client-side with rc=-4, and the action dies at Sending with -4030 "send msg failed" — which reads like a network or signing problem. (The runner issues install_device_cert twice, lan_only=1 then lan_only=0; empirically neither call alone puts app_cert_install on the wire.)
• --client-name BambuStudio. The cloud answers POST /my/task with 403 "The client does not have access rights to the content." for any other X-BBL-Client-Name, so an honest client name never reaches the body you want to inspect.
• --user-info @<obn.auth.json> even for the LAN-only runs — signing material comes from the cloud session.
• --auto-stop on anything that can actually start a print.

Two safe dry runs: --action sdcard_print with dst_file naming a file that isn't on the SD card publishes the full project_file and uploads nothing, and reusing sequence_id "20001" across process restarts makes firmware reject with mqtt message verify failed / err_code 84033544 — in both cases the plugin's serialization is already on the wire, which is all the probe needs. See the 84033544 readings block in §10.04.

Finally diff the key sets of the captured bodies rather than eyeballing them: the control run is the baseline, and a key that appears only in the numeric run (plateId) is the whole point of the exercise.

8.8.8. POST /my/task body: which keys are optional

Full field sweep against stock 02.08.02.54, probing one PrintParams field at a time with the method from §8.8.7 (four local_print_with_record runs under mitmdump). The starting point was a key-set diff between a stock body and our own builder, which showed four keys we sent that stock did not, one key we never sent, and one value mismatch.

Half the body is optional. Stock omits a key outright rather than sending a default, and the gate is always the individual field — never task_use_ams:

Key	Source field	Emitted when	Notes
amsMapping	ams_mapping	string non-empty	Forwarded verbatim. task_use_ams=true with an empty string does not bring it back; task_use_ams=false with a filled string still emits it. Sending [-1] as a stand-in over-reports a no-AMS job.
amsMapping2	ams_mapping2	string non-empty	Re-keyed snake→camel by the plugin itself ({"ams_id":2,"slot_id":3} → {"amsId":2,"slotId":3}), which is why Studio's snake_case never reaches the wire and why the endpoint only accepts camelCase (issue #48).
nozzleMapping	nozzle_mapping	string non-empty	Verbatim.
extrudeCaliManualMode	extruder_cali_manual_mode	!= -1	-1 is Studio's "not set"; 0 and 1 are both emitted.
designId	stl_design_id	!= 0	Key we were missing entirely. Number, verbatim.
plateId	queue_plate_id	parses non-zero	§8.8.1.
svcContext	svc_context	non-empty	§8.8.1.

cfg is the same bitmask as LAN project_file, and it has a second known bit:

Bit	Value	Driven by
0	1	task_ext_change_assist
1	2	unknown — no field this ABI exposes moves it, try_emmc_print included
2	4	task_timelapse_use_internal

Probed separately in both serializations: a /my/task run with task_ext_change_assist alone gave cfg:"5" alongside internal timelapse and cfg:"1" alone, and an sdcard_print run gave "cfg":"1" in the published project_file. task_record_timelapse stays out of cfg in both — it rides in the separate timelapse boolean, and a run with task_record_timelapse=true and nothing else set still reported cfg:"0".

sequence_id is not a constant. It counts POST attempts within one create_task call: the first is always 20001, and retries bump it (20002, 20003 observed on the 400 and 403 retry bursts), while a later separate create_task starts over at 20001. A builder that never retries only ever needs 20001 — our previous hardcoded 20000 was simply wrong.

Confirmed 1:1 passthroughs. autoBedLeveling / extrudeCaliFlag / nozzleOffsetCali are plain ints from auto_bed_leveling / auto_flow_cali / auto_offset_cali (2/3/4 came through unchanged, so they are not coerced to booleans); bedType, oriModelId, oriProfileId, plateIndex are verbatim; amsDetailMapping and nozzleInfos are the caller's JSON. The server wants amsDetailMapping[].ams as a number — a string sentinel there returns 400 type mismatch for field "amsDetailMapping[0].ams".

Fed from outside this ABI. cover stayed "" and filamentSettingIds stayed [] even with every PrintParams string filled with sentinels, so neither is reachable through the print ABI. preset_name, comments, extra_options, dev_name, try_emmc_print, print_type and connection_type produce no key at all (print_type="OBNPRINTTYPE" and connection_type="OBNCONNTYPE" on local_print_with_record left the /my/task body unchanged and never appeared in any other HTTPS request).

plateIndex is verbatim. A probe with plate_index=2 produced "plateIndex":2 (HTTP 200); the LAN param on the same ABI is Metadata/plate_2.gcode.

One deviation we keep. Stock re-serializes nested objects through a JSON object, normalising their key order ({"id":0,"type":…,"diameter":…} came back as {"diameter":…,"flow_type":…,"id":0,"type":…}); but key order is meaningless to the endpoint. Top-level order does match: stock emits the body alphabetically, so designId sits between cover and deviceId, and nozzleMapping between nozzleInfos and nozzleOffsetCali. A fully populated body is pinned byte-for-byte in tests/cloud_print_test.cpp.

Community quirk index: ams_mapping 8-element trap #2732 — see §16. Community quirk index.

Hub: §8.