Problem:
- PlaylistSource reads cached files faster than FlacCacheSink writes them
- FLAC decoder encounters EOF and stops playback prematurely
- First track doesn't play completely (stops at prebuffer point ~600ms)
- Needed to differentiate:
* Temporary EOF: file still being written (wait and retry)
* Real EOF: file completely written (stop decoding)
Solution:
1. Added Cache::is_download_complete() method (pmocache/src/cache.rs:735)
- Checks for existence of completion marker (.complete file)
- Marker created only when file is fully written and closed
- Fast synchronous check (no async overhead)
2. Modified decode_and_emit_track() (playlist_source.rs:337)
- On EOF: check if completion marker exists
- If no marker: file still being written → wait 50ms and retry read
- If marker exists: file complete → finish decoding
- Reduced wait from 100ms to 50ms for better responsiveness
Benefits:
✅ First track now plays completely (not just prebuffer portion)
✅ Progressive caching still works (playback starts at ~600ms)
✅ Proper EOF handling (no premature stops)
✅ Efficient polling (50ms retry interval)
✅ Works for both fresh downloads and cached files
Tested:
- Fresh download: EOF retries visible in logs every ~50ms
- File plays until completion marker created
- No premature track termination
Related to previous optimization (commit d8594e7) that made
prebuffer→playlist push immediate (76ms instead of 19s).