bvandeusen
24d330424f
Track identity was file_path, so a file that came back renamed or in a different directory looked like a deletion plus an unrelated new track: the old row kept the like and every play_event while a fresh zero-history row appeared, and nothing connected them. A liked song read as unliked, its play count reset, and Rediscover could offer it as a discovery — silently. Renumbering an album was enough, which is what happened to the operator's copy of Minutes to Midnight. Adoption re-points the existing row's file_path at the new location and clears its missing mark. The normal UpsertTrack then conflicts on file_path and updates THAT row, so the track id survives and likes, plays and playlist memberships travel with it — and clients see an update rather than a delete-and-create, so no cache churn either. Matching is MBID first (identifies the recording, so it survives a re-encode), then file_size + duration_ms for untagged files. Both fingerprint components must be non-zero: duration_ms is 0 when ffprobe failed, and matching 0 against 0 would pair up unrelated broken files. Only rows already marked missing are eligible — a row whose file is present elsewhere is a duplicate, not a move, and re-pointing it would corrupt the copy that still exists. An ambiguous match inserts fresh rather than adopting one arbitrarily: a fork is recoverable later, a wrong merge isn't. Scan is now three phases, and the order is the point. Adoption can only claim a row that is ALREADY marked missing, but reconcile previously ran after processing — so a rename performed while the server was down surfaced the deletion and the addition in the same scan, the new path inserted first, and the fork became permanent. Enumeration is therefore separated from processing so reconcile can run between them: walk (paths only, no tag reads or probes) -> reconcile -> process in walk order. Consequence worth knowing: when reconcile refuses (an absent root, or a reorganisation exceeding the 25% mark cap) adoption cannot fire and renamed files fork as before. That's the pre-#2528 behaviour rather than a new failure, and the warning now names it. The old outer walk-error branch was unreachable — the callback always returned nil, so WalkDir never surfaced an error — and verifyRootsPresent is the real protection, so enumerate counts walk errors instead of pretending to abort on them.