[chrisae9]

Summary

A guest startup can be cancelled after Plex selects the media but before the stream loads. The selected metadata then incorrectly satisfies the “already playing” check, leaving an empty decoder masked as buffering until a browser reload.

Treat masked startup media as not yet playing. When a host state update finds that startup interrupted and no source change running, allow one media retry per room/host/media selection. Successful playback resets the retry allowance. Add cancellation/retry diagnostics without credentials.

Verification

• Regression harness reproduces cancellation after the Plex decision with zero decoder loads. It fails against the previous implementation and passes with the fix, including unchanged-media deduplication after recovery.
• A second harness case verifies that active source changes are left alone and repeated host updates permit only one retry.
• Full server and frontend suites passed: 173 server tests and 649 frontend tests. Production build, lint, expanded fuzz, and required CI are checked before promotion.
• The original live incident logs show the guest completing its decision request without a subsequent stream request. The stranding/retry defect is reproduced; the initiating cancellation is not conclusively attributed.
• Repeat live verification will exercise two real Plex players, an interrupted guest startup, recovery, host seeking, and Stop without disturbing other rooms.