[juliusvaart]

Resolves

No issue filed. Found while testing on a live account.

Summary

A folder renamed while the working-set scan is reading it is reported as deleted, and macOS removes it from disk while it still exists on the server.

The scan reads from a snapshot of the materialised set taken before any request goes out. If a rename or move commits while the PROPFIND for the old path is in flight, the server answers 404. That 404 is about a path nobody occupies any more, not about the item, but the scan treats it as a deletion:

• the item is reported deleted, so the system removes the folder locally;
• its database row is written back with the pre-rename name and deleted set.

survivingOcIds does not catch this. It only spares items that reappear in the pass's updates or creations, and the move has already written the correct row, so the new parent's depth-1 read finds the item unchanged and never reports it.

The fix

Before believing the 404, the scan looks up the item's current row. If the row now points somewhere else, the path was stale and the item is skipped. Otherwise the 404 counts as a deletion, as before.

The change is a guard of about 10 lines in Enumerator+WorkingSetScan.swift.

Tests

New RemoteChangePropagationTests.testA404ForAPathTheItemHasMovedAwayFromIsNotADeletion: the server has already renamed the folder, and the rename reaches the database while the scan's read of the old path is in flight. It fails without the fix and passes with it.

Full suite, run locally with swift test on top of master (edf26f2b1b):

• 390 XCTest (6 skipped, 0 failures) and 195 swift-testing tests, on master 3527955c09.
• The only failures were the known timing-flaky EnumeratorTests cases (testWorkingSetChangesBatchMixingUpdatesAndDeletions, testWorkingSetChangesResumeAcrossNewEnumeratorInstances, testTrashChangeEnumeration). They fail the same way on unmodified master: three runs there gave 1, 0 and 3 failures. A rerun of EnumeratorTests on this branch was clean.
• swiftformat --lint and git diff --check are clean.

Checklist

• Sign-off message is added to all commits.
• The commit messages are following The Conventional Commits specification.
• The commit history is clean with no merge commits.
• Uploaded screenshots from before and after for UI changes.
• Test(s) added to branch, with before/after results included in PR description, for performance improvements where applicable.
• Documentation has been updated or is not required.
• Backports requested where applicable (critical bugfixes).
• Labels added where applicable (bug/enhancement).
• Milestone added for target version.

AI (if applicable)

• The content of this PR was partly or fully generated using AI
  • I have read the guidelines for AI-assisted contributions.
  • I have read Nextcloud's AI Contribution Policy.

The code, tests and this description were written by Claude Code (Claude Opus 5.5) at my request, from a diagnosis of my own account's logs and database.

🤖 Generated with Claude Code

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