GB-M0-R8 — Buds2 Pro Spatial Sensor / Head-Tracking Reuse Spike

[PNHD]

Goal

After the base Buds management transport in #2 is physically proven, determine whether GalaxyBridge can expose Galaxy Buds2 Pro spatial-sensor/head-tracking data without rebuilding the protocol from zero.

Dependency

HARD BLOCKED until #2 proves a stable, non-destructive management RFCOMM path on the owner's physical SM-R510 while iPhone audio remains usable.

REUSE-FIRST SOURCE

APPROVED_FOR_ADAPTATION

timschneeb/BudsPro-Headtracking

• license: MIT
• pinned snapshot: 63b321aa0536fd28233eaaf3a05c4f3b3f8201fe
• reusable semantics:
  • modern 0xFD ... CRC16-CCITT ... 0xDD packet framing
  • spatial enable message 0x7C
  • spatial data message 0xC2
  • spatial control message 0xC3
  • attach / detach / keepalive controls 0 / 1 / 4
  • gravity quaternion event 32
  • signed 16-bit quaternion extraction / 10000 scaling

Do not port its Python Bluetooth/thread architecture. Adapt the small protocol/state machine into GalaxyBridge Kotlin only after R4 establishes the correct SM-R510 transport/service.

REFERENCE_ONLY

timschneeb/GalaxyBudsClient — GPLv3

• current Buds2 Pro spec declares SpatialSensor and firmware-gated HeadTracking
• use only to cross-check capability/message behavior

Freeyourgadget/Gadgetbridge — AGPLv3

• old Galaxy Buds protocol independently documents spatial-audio enable/control command families
• no code copy

Critical compatibility warning

The MIT head-tracking project was originally built for Galaxy Buds Pro and later broadened service-name matching for Buds2-family FACTORY RFCOMM records. Public issue reports include Buds2 Pro sessions that connect but then stutter/disconnect without stable spatial data.

Therefore source existence is NOT a hardware PASS for SM-R510.

PoC after #2

1. use the exact stable RFCOMM service selected by the R4 hardware result
2. send only the documented spatial enable + attach sequence
3. require explicit attach ACK
4. enforce bounded keepalive/retry behavior
5. parse quaternion frames with strict length/CRC checks
6. record frame rate/jitter/dropout for at least 5 minutes
7. verify audio remains usable on iPhone
8. detach/disable cleanly

Safety

• no gyro calibration/reset/debug-reset commands
• no firmware writes
• no unknown message IDs
• no brute-force/fuzzing

Classification

Final recommendation after hardware test:

• HEAD_TRACKING_STABLE
• HEAD_TRACKING_UNSTABLE
• HEAD_TRACKING_UNSUPPORTED_ON_CURRENT_SM_R510

PM handoff

Implementation agent must report model/effort, branch, baseline/final HEAD, commits/files, commands, build/tests, exact physical evidence, frame-rate/jitter/dropout measurements, owner steps, risks and final git status, then STOP without merging or starting another task.