Round 43 made the merge report honest, and in doing so made its one real
limitation impossible to miss: every merge was a union, so a song removed from a
playlist on one machine was handed straight back by the other on the next sync,
and a track deleted from the library came back with it. A deletion you cannot
make stick is not a deletion.
The union was there for a real reason — two copies with no common ancestor
cannot tell "A added this" from "B removed it" — so the missing evidence is
written down instead of inferred. New lintunes/tombstones.py: a playlist keeps
track_events {track id: [when, add|remove]}, the library keeps deleted_tracks
{track id: when} in library_metadata.json, and a merge applies the newest event
per track across both copies. A removal beats a copy that merely still had the
song; a deliberate re-add afterwards beats the removal; a track nobody touched
still merges as a union, which stays the safe behavior where there is no
evidence either way.
Deliberately not "the newer copy wins wholesale": that one-liner silently drops
a song the other machine added while you were removing one, which
test_an_unrelated_addition_is_not_lost pins.
Events are recorded in the funnels that already exist — _set_track_ids diffs
before/after so a reorder records nothing, _remove_tracks stamps the library,
_restore_tracks clears it so Ctrl+Z takes the tombstone back — and pruned after
30 days at the save boundary.
Three edges worth naming:
* Track ids are never reused. The next id came from max(library.tracks), so
deleting the highest-numbered track freed its id, and the next import would be
dropped on sight by the dead id's own tombstone on every machine.
* library_metadata.json is merged before library.json, since it carries the
record the library merge is filtered against and rglob order is not a plan.
* A merge applying a deletion never touches a music file — it drops the library
entry only, and test_a_merge_never_touches_a_music_file fails the run if
send_to_trash is so much as called. Applied removals grade WARNING and name
the song.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Y9ZEFi4qNJ39FMiBtiAxy2
