Tapping a system-playlist PlayCircleButton before the mix had loaded
silently stalled — three failure modes all looked identical to the
user (PlayCircleButton's spinner clears with no playback):
- api.systemShuffle returns empty (mix not built server-side yet)
→ silent return at `if (refs.isEmpty)`
- api call slow / hung → spinner spins indefinitely (no client
timeout was set; Dio default is unlimited)
- api throws → uncaught; spinner finalizer clears it silently
Bundle:
- 8s `.timeout` on the systemShuffle / get call; TimeoutException
→ "Couldn't load playlist — check your connection"
- empty refs after filtering → "Mix isn't ready yet — try again
in a moment"
- other throws → "Playlist load failed: <error>"
- thread BuildContext through and capture ScaffoldMessenger before
the first await so no `use_build_context_synchronously` lint
No pre-warm — system playlists are intentionally uncached per the
api endpoint comment ("varies per play"); pre-warming would decide
the shuffle order at home-screen load instead of at tap, breaking
the fresh-per-play contract.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
bvandeusen
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