fix: render downloaded albums in offline library tab

[dylanjeffers]

Summary

• Library → Albums tab in offline mode showed skeletons forever instead of the user's downloaded albums. The banner correctly read "Displaying Available Offline Content" but no cards ever resolved.
• useLibraryCollections's offline branch returned Object.keys(collectionStatus) directly. Three problems compounded:
  1. The keys are strings, but useCollection (used inside each CollectionCard) keys its TanStack cache by number — every per-card lookup missed cache, fell to if (!partialCollection) return <CollectionCardSkeleton /> (CollectionCard.tsx:86), and rendered a skeleton forever.
  2. The literal 'favorites' sentinel (DOWNLOAD_REASON_FAVORITES) lives in the same map and was being passed downstream as a "collection id."
  3. No filtering by collectionType, so the Albums tab also pulled in playlist IDs and vice versa.
• Additionally, the hook returned isPending/isLoading from the network query, which stays true indefinitely under TanStack's default networkMode: 'online' when offline. With an empty collectionIds, that drove the outer CardList skeleton too.

Fix

• Build numeric offlineCollectionIds (drop the 'favorites' sentinel, ignore non-numeric keys).
• Resolve the cached collections via the existing useCollections hook, then filter by is_album per collectionType and apply the existing text filter.
• Override isPending/isLoading/hasNextPage/isFetchingNextPage to offline-appropriate values (driven by isDoneLoadingFromDisk) when not reachable, so the outer skeleton no longer gates on the paused network query.

Single file changed: packages/mobile/src/screens/library-screen/useLibraryCollections.ts. Both the Albums and Playlists tabs share this hook, so both are fixed.

Test plan

• Online: Library → Albums and Playlists tabs render the same set as before (network path unchanged).
• Online → download an album → toggle airplane mode → open Library → Albums tab. Banner shows; the downloaded album renders (no skeleton).
• Same flow, Playlists tab: only downloaded playlists render (no album leakage, no 'favorites' ghost card).
• Offline with no downloads: empty state renders (skeleton no longer stuck because isPending resolves once disk rehydration completes).
• Filter input still narrows offline results by name.
• npx tsc and npx eslint clean for useLibraryCollections.ts.

🤖 Generated with Claude Code

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