[teamleaderleo]

HOLD: abandoned with #28675, which it is stacked on. To be closed; do not land.

Stacked on #28675 (base lane/sync-push-keeps-machine-edits; it retargets to feat-cmux-next when that lands).

cmux link sync push: when this Mac deleted a file that the machine changed since the last push, the push leaves the machine's copy in place, as before. It now also keeps the file in the record, so a pull reports the delete here against the edit there as a conflict.

Why

The Codex review of #28675 named this as a follow-up (P1): "A machine-edited file deleted locally is left on the machine but removed from the next manifest... A subsequent pull therefore treats the machine file as new and restores it, silently choosing the machine edit instead of reporting the expected delete-vs-edit conflict." The bug was already on feat-cmux-next; #28675 didn't add it.

What changes

In the delete pass, a file the machine still has but changed since the last push keeps the last push's record entry, and is counted as kept. A file the machine still has as the push left it is deleted, as before. A file missing on both sides drops out of the record, as before. The count uses saturating_add, so the Rust panic ratchet gets no new hit.

Tests

link_sync a_file_deleted_here_but_changed_on_the_machine_stays_a_conflict_after_a_push:

• after a push, the machine edits notes.txt and this Mac deletes it;
• a second push leaves the machine's copy (kept: 1);
• a pull reports notes.txt as a sync_conflict and doesn't bring the file back here.

The test is committed before the fix (4b22f75). The red and green results run on cmux-ci at this head and will be added here.

Observed / Not run

• Observed: rustfmt is clean with the repo's config.
• Not run locally: cargo (cmux-tui runs on CI only).

Changelog

Fixed: Bring Back Local reports a file you deleted on this Mac but changed on the Cloud machine as a conflict, instead of bringing the machine's copy back.

Risk: normal. Sync record only; nothing new is deleted.

Agent session: agent session

🤖 Generated with Claude Code

[teamleaderleo]

Closing this one; I own it. It was stacked on #28675, which is closed (the reason is there). The case it covers stays as it is on feat-cmux-next: a file deleted on this Mac that the machine changed is left on the machine but dropped from the record, and a later pull brings it back. Changing that is part of the same sync-semantics question; it's noted on #28675 and with #28111's owner.