- UART binary mode switch mechanism: enter handshake marker '[ota] binary
mode ON', explicit exit via OTA_ABORT (immediate), 10s idle fallback
(was 3s, must exceed the host retry window); host resync by CR probe
- fix: otaIdleMs not re-armed on mode entry - every second 'ota' entry was
kicked out by an instant idle timeout (leftover count from prior session)
- lossy-link tolerance: device drops partial frames after a 100ms byte gap
so host resends re-align; OTA session is now single-owner (second BEGIN
on another channel gets BAD_STATE)
- ble_ota_update.py: wait for the enter marker instead of blind sleeps,
per-frame resend (2s x3), BAD_STATE+expected-offset treated as implicit
ack for duplicate DATA/BEGIN (resync after ack loss), stage-labeled
timeouts with raw-rx dump
- verified on hardware: UART OTA full pass (55.7KB/41s, 4-5 lost frames
auto-recovered) + BLE OTA regression pass; docs: dev log 44,
ble_protocol.md 6.6 rework, AGENTS.md sync
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