fix: prevent data loss in skills sync on copy/update failure#563
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teknium1 merged 1 commit intoNousResearch:mainfrom Mar 7, 2026
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Two bugs in sync_skills(): 1. Failed copytree poisons manifest: when shutil.copytree fails (disk full, permission error), the skill is still recorded in the manifest. On the next sync, the skill appears as "in manifest but not on disk" which is interpreted as "user deliberately deleted it" — the skill is never retried. Fix: only write to manifest on successful copy. 2. Failed update destroys user copy: rmtree deletes the existing skill directory before copytree runs. If copytree then fails, the user's skill is gone with no way to recover. Fix: move to .bak before copying, restore from backup if copytree fails. Both bugs are proven by new regression tests that fail on the old code and pass on the fix.
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Summary
Two bugs in
sync_skills()that cause silent data loss when filesystem operations fail:Bug 1: Failed copy poisons the manifest
When
shutil.copytreefails (disk full, permission error, etc.), the skill is still recorded in the manifest. On the next sync, the skill appears as "in manifest but not on disk" — which is interpreted as "user deliberately deleted it." The skill is never retried.Before:
manifest[skill_name] = bundled_hashruns unconditionally after the try/except block.After: Only written to manifest on successful copy or when the destination already exists.
Bug 2: Failed update destroys the user's copy
shutil.rmtree(dest)deletes the user's skill directory beforeshutil.copytreeruns. Ifcopytreethen fails, the skill is gone with no way to recover.Before:
rmtreethencopytree— no rollback on failure.After:
shutil.moveto.bakbackup, thencopytree. Ifcopytreefails, the backup is restored.Test plan
Both bugs are proven by regression tests that fail on the old code and pass on the fix:
test_failed_copy_does_not_poison_manifest— patchescopytreeto raiseOSError, verifies the skill is NOT in the manifest, then runs sync again and verifies it succeedstest_failed_update_does_not_destroy_user_copy— patchescopytreeto fail during update, verifies the user's original skill directory still exists