# cold-boot-fixture (AZ-407 / AZ-419)

`cold_boot_fixture.json` is a frozen FC pose snapshot at flight-resume
time. The file is consumed by:

* **AZ-419 (FT-P-11 cold-start init)** — secondary path
  (`origin_source == fc_ekf` per ADR-010): loaded into the SITL via
  the standard parameter-load path. The SUT cold-starts with no
  Manifest `takeoff_origin`, and the test asserts the first outbound
  estimate lands within ±50 m of the snapshot pose.
* **NFT-PERF-03 (cold-start TTFF)** — same loading path, with
  performance instrumentation around the time-to-first-fix metric.

## Schema (v1)

```json
{
  "_schema": "cold-boot-fixture/v1",
  "global_position_int": { "lat_e7": ..., "lon_e7": ..., "alt_mm": ..., ... },
  "attitude": { "roll_rad": ..., "pitch_rad": ..., "yaw_rad": ..., ... },
  "ardupilot_param_overrides": { ... },
  "inav_serial_rx_overrides": { ... }
}
```

The `global_position_int` block uses the canonical MAVLink
`GLOBAL_POSITION_INT` units (lat/lon scaled by 1e7; alt in mm).

## Provenance

| Field | Source | License |
|-------|--------|---------|
| Lat / Lon | Derkachi sector centre (50.075° N, 36.150° E) | Synthetic — chosen from the Derkachi route bbox |
| Alt | 100 m AGL | Synthetic placeholder; refined when D-PROJ-3 supplies the production scenario |
| Attitude | Level flight, heading 0° (north) | Synthetic — chosen to match the parametrize matrix's default |

Fully synthetic; no third-party data. Re-distributable under this
repository's license.

## Loading path

* **ArduPilot**: `mavproxy.py --master=... --cmd="param load cold_boot_fixture.json"`
  followed by a `FAKE_GPS` injection sequence (handled by the AZ-419
  fixture loader; this README only documents the file itself).
* **iNav**: MSP2 `SET_HOME` message + `MSP2_SENSOR_GPS` injection. The
  per-FC wiring is handled by the AZ-419 fixture loader.

## Verification

The AZ-407 unit test
`e2e/_unit_tests/fixtures/test_cold_boot_fixture.py` asserts:

* The file is valid JSON
* The `_schema` field equals `cold-boot-fixture/v1`
* All required numeric fields are present and within physically
  reasonable bounds (±90° lat, ±180° lon, > 0 alt, etc.)

AC-4 (SITL loads the pose within ±1 m of the lat/lon/alt fields) is
verified by AZ-419's FT-P-11 test inside the Docker-bound runner —
that path requires SITL, which the AZ-407 unit test layer cannot
exercise.

## Owned by

AZ-407 (this file) + AZ-419 (the loader that consumes it).