The apply_patch language documents `*** Add File` and `*** Move to` as
strictly non-overwriting (create / rename), but the fs-level create and
rename paths in applyNormalizedPatch wrote through to the resolved target
without checking whether it already existed. Existing destinations were
silently replaced, and in the rename case the source was also deleted.
The multi-file executeApplyPatchPerFile aggregator caught each per-file
exception, appended an error entry, and kept iterating. Later files
still ran against an inconsistent post-state, and the aggregate result
had no top-level isError — so a mixed partial application looked like a
successful edit to the agent loop.
Changes:
- Add fs.exists guards before the create write and before the rename
write/delete in packages/coding-agent/src/edit/modes/patch.ts. Both
reject with ApplyPatchError before any side effect.
- Make executeApplyPatchPerFile in packages/coding-agent/src/edit/index.ts
stop at the first per-file failure, list applied vs. skipped files in
the aggregate text, and propagate isError, matching executeSinglePathEntries.
- Rename the two apply-patch scenario fixtures (010_move_..., 011_add_...)
that pinned the buggy overwrite behavior to _rejects_ variants, and
flip their expected/ trees so source and pre-existing destination
remain byte-identical after the rejected apply.
- Cover both failure modes with new regressions in
packages/coding-agent/test/core/apply-patch.test.ts and a new
packages/coding-agent/test/core/apply-patch-multi-file.test.ts.
Fixes#4074
roboomp