Audit connection reliability and reconnection

[erik-sutton95]

Ongoing audit of the BLE → SoftAP → UDP spine: stay connected, recover cheaply, never black the feed with a bad repair.

This is audit first, then small remaining PRs. Most of docs/connection-reliability-plan.md is already in tree. Do not re-implement the types.

Related: Android parity (workstream 7) · Multicast · roadmap index

Already implemented

• Core: LinkDiagnosis, ConnectTimeline, FeedWatchdog, SessionRecovery, ReconnectBackoff, CameraLinkHealth, SoftAP persist helpers
• iOS: event-driven handshake poll, persist hotspot for saved cameras, VT from first parameter sets, warm reconnect when SoftAP is still up, watchdog enable-once (never 1 Hz 0x09/0xa8)
• Android: live-enable storm guard only; BLE/SoftAP loss still failLink → FAILED

Hard rules stay: do not spam 0x09/0xa8; do not tear UDP because a SET timed out while HEVC/AVC is still arriving.

Audit (no behavior change)

• Policy map: LinkDiagnoser vs FeedWatchdog.tick vs CameraSession branches. LinkDiagnoser is unused outside tests; .rehandshake never maps from repair(for:)
• Confirm rebuildVTSession in the watchdog currently rebuilds UDP, not VT
• 5+ minute take logs (feed: stall / feed: black) on Pocket 4 Pro and Nano, LUT on, AF-C hunt, background/foreground
• Connect timeline: gatt/pair/path/hs/enable — is idr= still worth adding?
• Saved-camera persist vs first-pair join-once
• Android delta: 350 ms handshake sleep × 20, no last-frame hold, HEVC-only decoder

Remaining implementation (after the audit, one PR each)

• Single repair owner on iOS (call LinkDiagnoser or delete/narrow it)
• Parallel TCP 7001 poke + path wait (DatalinkDriver.open leftover)
• Android FeedWatchdog + SessionRecovery over JNI
• Update docs/feed-watchdog.md if the 3–5 min black well is gone or still open

Done when

A written audit comment on this thread, plus the leftover PRs filed or closed. Hardware proof that a 5+ min take with LUT survives congestion without a GOP reset.

[erik-sutton95]

Tracked as maintainer task #93. Android recovery slice is #78.