Description

Fix release-only QR scanner initialization and crash-prone concurrency and background-service paths.

Changes

• Preserve the no-argument constructors ML Kit discovers through Firebase component registration. R8 previously retained the registrar classes but removed their reflective constructors.
• Serialize security-cache traversal and paired timestamp/set updates; avoid size-based snapshots of concurrently changing relay connections.
• Promote the mesh foreground service before transport initialization. Handle denied starts, denied promotions, and revoked permissions without crashing callers or scheduling sticky retries. Preserve the activity retry after a denied start and clear it only when a later request is accepted.
• Recheck Wi-Fi Aware discovery permissions after attachment, contain revocation during publish/subscribe, release partial sessions, and avoid permission-denial restart loops.
• Add deterministic regression tests and an opt-in minified release scanner test with a synthetic QR frame. Normal production signing and dependency versions remain unchanged.

Verification

• Phone unit suite: 664 passed, 3 skipped; Wear unit suite: 227 passed.
• Foreground-service tests cover API 31 and 34; Wi-Fi permission-race tests cover API 32 and 34. The activity retry regression reproduces before the fix for both system start denial and permission revocation; all four cases pass after the fix.
• Release scanner creation, actual synthetic QR decoding, and frame cleanup: 2 passed on API 36. The scanner crash was reproduced before applying the fix.
• Phone and Wear debug/release APK builds and separate production AAB builds succeeded.
• testDebugUnitTest lintDebug clientRewriteContractTest completed successfully after the retry fix. Lint adds no findings compared with the existing PR report; the existing backlog remains.
• Fresh lint comparison against main: no added findings in either module. The existing lint backlog is not resolved by this PR.
• Dependency pins are unchanged; lockfile additions cover only release instrumentation configurations.
• git diff --check and the scanner regression script syntax check passed.

Risk and remaining validation

• Foreground-service startup ordering and Wi-Fi Aware teardown behavior change. Physical Mesh Lab coverage (broadcast, dm, session_recovery, plus Wi-Fi Aware permission/recovery checks) is not run and remains a release gate. Emulator tests do not establish physical BLE/NAN correctness.
• One full-suite run failed in the unchanged randomized FragmentManagerTest reassembly test; the subsequent complete suite passed. That intermittent failure was not diagnosed or modified here.
• -PreleaseUiTests=true uses debug signing for instrumentation only. Those test APKs must not be distributed as production releases.
• No layout, protocol, storage-format, or version-number changes. No release artifacts are included.

Checklist

• Performed a self-review.
• Added automated regression coverage.
• Reported verification results and outstanding hardware validation.
• Physical Mesh Lab validation before release.