You can now drop a music file onto the story content area or pick one through the new "Import audio" button in the add-clip popover. Both call POST /generate/import which writes the file to data/generations/<id>.<ext>, probes duration via librosa, and inserts a Generation row pointing at a singleton "Imported Audio" profile (created lazily on first import). The existing addStoryItem flow takes over from there — the timeline doesn't care that the row didn't come out of TTS.
Engine field on the row is "import"; it's surfaced on StoryItemDetail so the chat list shows a music icon instead of the (missing) profile avatar and both the dropdown and the track-editor toolbar hide the Regenerate action — there's nothing to regenerate. Accepted formats: wav/mp3/flac/ogg/m4a/aac/webm, capped at 200 MB. Translation keys added across en/ja/zh-CN/zh-TW.
Two changes to address the race condition causing "Failed to split clip":
Backend (stories.py): Added with_for_update() to the item query in
split_story_item so concurrent requests for the same clip are
serialized via a row lock instead of racing.
Frontend (StoryTrackEditor.tsx): Guard handleSplit with
splitItem.isPending to prevent rapid double-clicks from firing
multiple mutations before the first completes.
Fixes#366
Co-authored-by: Matt Van Horn <[email protected]>