Audit of every Android↔server connection point (2026-06-11) cleared the
silent-contract class that caused the events `type` bug, but surfaced a
cluster of offline/playback-robustness defects. Fixes:
1. Playback double-count on background. PlayEventsReporter no longer
enqueues a partial play_offline + leaves the live row open on every
screen-lock. closeCurrent() now routes by whether the server has an
open row: close-by-id (durable PLAY_ENDED on failure) when it does,
offline only when no row exists, and a no-op while a play_started is
in flight (the server auto-closes that orphan). onStop only durably
closes a *paused* play — a still-playing one is left to the live path
under the foreground service. Adds the PLAY_ENDED mutation kind.
2. Replayer poison rows. MutationReplayer now classifies each replay as
SENT / DROP / RETRY: permanent 4xx (and corrupt payloads) are dropped
instead of retried forever; 408/429/5xx/transport still retry.
3. Offline-play / close-by-id idempotency (server). RecordOfflinePlay
dedups on (user, track, started_at); RecordPlayEnded skips a second
skip_events insert when re-closing an already-ended row. Makes the
at-least-once replay safe against lost-response duplicates.
4. Like-toggle collapse. Replayer drops like-toggles superseded by a
later toggle for the same entity, so partial-failure + differential
retry can't invert the final like state.
5. Connectivity-return trigger. MutationReplayer + SyncController now
also drain/sync when NetworkStatusController recovers to Healthy, so
an offline→online transition mid-session doesn't wait for a cold
start. SyncController.syncSafe gains a single-in-flight mutex.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
bvandeusen
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