The #1 patch failure class in production (state.db mining, 250k-window)
is a re-send of an edit that already landed: 'old_string and new_string
are identical' (299 occurrences) plus a share of hunk-not-found errors
where the new text is already in the file. These errored, sending
models into re-read/re-patch loops.
New tools/fuzzy_match.is_already_applied(content, old, new) — a
conservative check requiring (1) non-trivial new_string (>=8 chars),
(2) EXACT presence of new_string, (3) old_string gone (unless
identical). Wired into three sites:
- patch_replace (replace mode): returns success + no_change: true +
an explicit note instead of the identical-strings / no-match error.
- V4A validation phase: an already-applied hunk validates as a no-op
so multi-hunk patches no longer fail wholesale when one hunk landed
in a prior call.
- V4A apply phase: mirrors the same skip so the two phases agree.
Genuine no-matches (new text absent) and half-applied renames (old
text still present) keep their error behavior — covered by tests.
Teknium