Follow-ups on top of @teyrebaz33's cherry-picked commit:
1. New shared helper format_no_match_hint() in fuzzy_match.py with a
startswith('Could not find') gate so the snippet only appends to
genuine no-match errors — not to 'Found N matches' (ambiguous),
'Escape-drift detected', or 'identical strings' errors, which would
all mislead the model.
2. file_tools.patch_tool suppresses the legacy generic '[Hint: old_string
not found...]' string when the rich 'Did you mean?' snippet is
already attached — no more double-hint.
3. Wire the same helper into patch_parser.py (V4A patch mode, both
_validate_operations and _apply_update) and skill_manager_tool.py so
all three fuzzy callers surface the hint consistently.
Tests: 7 new gating tests in TestFormatNoMatchHint cover every error
class (ambiguous, drift, identical, non-zero match count, None error,
no similar content, happy path). 34/34 test_fuzzy_match, 96/96
test_file_tools + test_patch_parser + test_skill_manager_tool pass.
E2E verified across all four scenarios: no-match-with-similar,
no-match-no-similar, ambiguous, success. V4A mode confirmed
end-to-end with a non-matching hunk.
When patch_replace() cannot find old_string in a file, the error message
now includes the closest matching lines from the file with line numbers
and context. This helps the LLM self-correct without a separate read_file
call.
Implements Phase 1 of #536: enhanced patch error feedback with no
architectural changes.
- tools/fuzzy_match.py: new find_closest_lines() using SequenceMatcher
- tools/file_operations.py: attach closest-lines hint to patch errors
- tests/tools/test_fuzzy_match.py: 5 new tests for find_closest_lines
Two hardening layers in the patch tool, triggered by a real silent failure
in the previous session:
(1) Post-write verification in patch_replace — after write_file succeeds,
re-read the file and confirm the bytes on disk match the intended write.
If not, return an error instead of the current success-with-diff. Catches
silent persistence failures from any cause (backend FS oddities, stdin
pipe truncation, concurrent task races, mount drift).
(2) Escape-drift guard in fuzzy_find_and_replace — when a non-exact
strategy matches and both old_string and new_string contain literal
\' or \" sequences but the matched file region does not, reject the
patch with a clear error pointing at the likely cause (tool-call
serialization adding a spurious backslash around apostrophes/quotes).
Exact matches bypass the guard, and legitimate edits that add or
preserve escape sequences in files that already have them still work.
Why: in a prior tool call, old_string was sent with \' where the file
has ' (tool-call transport drift). The fuzzy matcher's block_anchor
strategy matched anyway and produced a diff the tool reported as
successful — but the file was never modified on disk. The agent moved
on believing the edit landed when it hadn't.
Tests: added TestPatchReplacePostWriteVerification (3 cases) and
TestEscapeDriftGuard (6 cases). All pass, existing fuzzy match and
file_operations tests unaffected.
- Bug 1: replace read_file(limit=10000) with read_file_raw in _apply_update,
preventing silent truncation of files >2000 lines and corruption of lines
>2000 chars; add read_file_raw to FileOperations abstract interface and
ShellFileOperations
- Bug 2: split apply_v4a_operations into validate-then-apply phases; if any
hunk fails validation, zero writes occur (was: continue after failure,
leaving filesystem partially modified)
- Bug 3: parse_v4a_patch now returns an error for begin-marker-with-no-ops,
empty file paths, and moves missing a destination (was: always returned
error=None)
- Bug 4: raise strategy 7 (block anchor) single-candidate similarity threshold
from 0.10 to 0.50, eliminating false-positive matches in repetitive code
- Bug 5: add _strategy_unicode_normalized (new strategy 7) with position
mapping via _build_orig_to_norm_map; smart quotes and em-dashes in
LLM-generated patches now match via strategies 1-6 before falling through
to fuzzy strategies
- Bug 6: extend fuzzy_find_and_replace to return 4-tuple (content, count,
error, strategy); update all 5 call sites across patch_parser.py,
file_operations.py, and skill_manager_tool.py
- Bug 7: guard in _apply_update returns error when addition-only context hint
is ambiguous (>1 occurrences); validation phase errors on both 0 and >1
- Bug 8: _apply_delete returns error (not silent success) on missing file
- Bug 9: _validate_operations checks source existence and destination absence
for MOVE operations before any write occurs
