A save's OPFS session is torn down on a fixed 120 s timer; a sibling prune can then delete the file under an in-flight or reused download #134

Severity: medium

Where: chrome/player/modules/StreamSaver.mjs (after Utils.revokeWhenDownloaded(url, download)), chrome/player/modules/dash2mp4/mp4merger.mjs (destroy), chrome/player/modules/remux/remuxer.mjs, chrome/player/modules/hls2mp4/hls2mp4.mjs, chrome/player/network/opfs-worker.mjs (destroy keeps the directory, prune)

What happens

Utils.revokeWhenDownloaded(url, download);
setTimeout(() => {
  blobManager.close();
}, 120000);

close() stops the worker's heartbeat and deliberately leaves the session directory. prune() in any later init() (a player opening in another tab, the next save's own new FSBlob(), a merger) removes a directory whose heartbeat is older than 10 s. The result File (getSavedFile) and, on the non-OPFS merger paths, the getBlob(id) Files inside the returned Blob, are all backed by that directory. SaveManager keeps this.downloadURL for re-use.

Failure scenario

Save a 4 GB MP4 to a slow USB stick (Firefox copies a blob at tens of MB/s, so more than three minutes). At 120 s the worker closes; a player opening in another tab at 130 s prunes the session; the download is interrupted with no message. The same for a second click on Save for the same source after two minutes once any other FSBlob has initialised: the reused URL points at deleted files.

Suggested fix

Close the blob manager from the completion path revokeWhenDownloaded already tracks (give it a callback, or return a promise that settles when downloads.onChanged reports the download over) instead of a timer; revoke the reusable URL when its backing manager closes.

Confidence: medium-high (the prune timing is in the code; the long-download trigger is environmental).

From a line-by-line code review of the tree at 41363fd (2026-10-02). Each claim above was checked against the source before filing; the reproduction steps and line references are as of that commit.

Generated by Claude Code