feat(mobile): CollectionTile title tints to active color when a child track is playing

[dylanjeffers]

When any track inside a collection is currently playing, the mobile CollectionTile's title should match the active highlight that the per-row tracks already get — the same purple Audius uses for the playing track's title on TrackTile. Today the title is always rendered with the default text color, even while one of the collection's tracks is the one playing.

What changed

packages/mobile/src/components/lineup-tile/CollectionTile.tsx — derive isActive from the existing currentTrack selector and pass it to the title's color prop:

const currentTrack = useSelector((state) => {
  const trackId = getTrackId(state)
  return tracks.find((t) => t.track_id === trackId) ?? null
})
const isActive = currentTrack != null

<Text variant='title' color={isActive ? 'active' : 'default'} numberOfLines={1}>
  {collection.playlist_name}
</Text>

Why 'active' and not 'primary'

TrackTile / LineupTileMetadata use color={isActive ? 'primary' : 'neutral'} — but they import Text from app/components/core (the legacy app Text). CollectionTile uses Text from @audius/harmony-native, whose type union explicitly accepts 'active' for the same primary highlight. Both resolve to the Audius purple at render time; the prop names differ between the two Text components.

CollectionTileTrackList row highlight — already in place

The per-row track-title highlight inside CollectionTileTrackList already works correctly. Each TrackItem runs:

const isPlayingUid = useSelector((state) => getTrackId(state) === trackId)

…and applies isPlayingUid && styles.active (which sets color: palette.primary) to every text element in the row — index, title, and by <artist>. Confirmed by reading the current source — no change needed there. This PR only fixes the collection-level title that wraps that row list.

Selector choice

getTrackId (state.playback.playingTrackId) is the right selector for tile-highlight comparisons — its file comment makes this explicit:

these mirror what the legacy player slice used to expose. playingIndex / playingTrackId lag behind queue[index] until playSucceeded fires, which is what tile-highlight comparisons want.

Using getCurrentTrackId (queue[index].trackId) would flash the active color the instant playFrom dispatches, before the track has actually started playing.

Verification

• tsc --noEmit clean in packages/mobile
• Manual: open a feed lineup with a collection tile, start playing a track inside that collection — confirm the collection's title text turns the active purple.
• Manual: confirm the per-row track title in the collection's tracklist also turns purple for the playing track (pre-existing behavior, regression check).
• Manual: confirm tiles where none of the tracks are playing render with the default title color.

🤖 Generated with Claude Code

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