[bsagmoe]

• Add shared element transitions, frame snapshot handoff, and retained playback state for fullscreen video player
• Handle captionBar and statusBarsIgnoringVisibility window insets in drawer, profile, and video player controls
• Cache per-channel conversation states, generate unique message IDs and formatted timestamps
• Add RoomDatabase keep rule for R8 Full Mode (since so we can use the release build when installing on demo devices) and update instrumentation tests

[compose-devrel-github-bot]

⚡ Jetpack Compose Performance Review

No Jetpack Compose performance issues were found in the changed code.

Verified Best Practices in Changed Code

The newly introduced and modified code in .gemini/pr_diff.patch adheres strictly to Jetpack Compose performance guidelines across all audited categories:

1. Phase Deferral to Draw & Layout:

   • VideoThumbnail wraps animated alpha evaluations (hideUntilSnapshotReady and animatedPlayOverlayAlpha.value) inside Modifier.graphicsLayer { ... } rather than reading state during Composition.
   • rememberAnimatedVideoShape reads fractionState.value inside Shape.createOutline, deferring corner radius animation to the Draw/Layout pass and avoiding recompositions per frame.
   • fitVideoBounds uses Modifier.layout to compute fitted video constraints in the Layout phase rather than relying on subcomposition (SubcomposeLayout or BoxWithConstraints).

2. Elimination of Backwards Writes & Coordinate Observation:

   • FullScreenVideoPlayer replaces onGloballyPositioned and Compose MutableState with Modifier.onLayoutRectChanged(throttleMillis = 0, debounceMillis = 0) and a plain Ref<IntRect>, preventing recomposition loops, multi-pass layout churn, and 1-frame lags.

3. Deferred Shared Transitions in Lazy Lists:

   • VideoThumbnail gates Modifier.videoSharedBounds behind Modifier.onVisibilityChanged(minFractionVisible = 0.001f), preventing Lookahead passes and transition scopes from instantiating on pre-fetched or off-screen items during fast scrolling.

4. Optimized State Derivation & Non-Allocating Collections:

   • Messages uses remember(scrollState) { derivedStateOf { ... } } along with visibleItems.fastSumBy { it.size } from androidx.compose.ui.util to eliminate iterator allocations and avoid unnecessary recompositions while scrolling.
   • JetchatApp derives displayBackStack cleanly via remember(isMultiPane) { derivedStateOf { ... } }.

5. Lifecycle Retention & Main-Thread Offloading:

   • FullScreenVideoPlayer preserves ExoPlayer across configuration changes and shared-element transitions using retain(resolvedUri).
   • Video thumbnail extraction (extractInitialVideoFrame) is offloaded to Dispatchers.IO using MediaMetadataRetriever, and bitmaps are downscaled to 720px (downscaleBitmapIfNeeded) to minimize GPU memory pressure.