[kevmo314]

• chat_panel.dart: findChildIndexCallback looks keys up in a map built once alongside keys instead of a linear scan that allocated a Key per comparison (O(n²) when a long list shifts).
• uniqueKeys tracks the next suffix per repeated key instead of retrying from #1 each time. Suffixes are still numbered from the oldest, so keys stay stable as messages arrive.
• emote.dart: only the backend call is retried; JSON/fromJson errors can't succeed on retry, so they're reported right away and the cache is used. The test-only retryDelay/reportError parameters are replaced by @visibleForTesting top-level emoteRetryDelay/reportEmoteError.
• emote.dart: concurrent getEmotes calls for the same channel as the same signed-in user (the chat and the message input both fetch on channel open) share one in-flight fetch, so on a cold cache they don't both call the backend and write the cache file at the same time. The in-flight key and the disk cache are scoped by Firebase Auth uid (or anon), since Twitch emotes depend on who's signed in.
• views.dart: removed the defaultChannels alias and _channelsFromJson, inlining both into their single uses. Tests now check channels. channels no longer re-wraps the already-unmodifiable _channels.
• stream_preview.dart: check mounted/_isTwitch after the 2s quality delays before running JS, and cancel _overlayTimer in dispose.
• main.dart: isFatalFlutterError treats details.silent errors as non-fatal, and FlutterError.onError is a single recordFlutterError(details, fatal: ...) call.

flutter analyze is clean and flutter test passes (470 tests).

• AudioModel runs syncs one at a time (coalescing queued ones), so an older sync still awaiting the permission check can't land after a newer clear.
• The service stops via stopSelfResult(startId) and only drops foreground state when that succeeds, so clearing can't cancel a newer queued start.