Three granular patch-tool refinements from the Roo Code deep-dive (#507).
## Indentation preservation (fuzzy_match.py)
When fuzzy_find_and_replace matches via a non-exact strategy, the file's
indentation may differ from what the LLM sent in old_string/new_string
(common case: model sends zero-indent old/new for a method body that
lives inside an 8-space-indented class). Before this commit the
replacement was spliced in verbatim, producing a file with a broken
indent level that may still parse but is logically wrong.
The fix computes the indent delta between old_string's first meaningful
line and the matched region's first meaningful line, then re-indents
every line of new_string by that delta. Exact-strategy matches are
untouched (passthrough). Same approach as Roo Code's
multi-search-replace.ts:466-500.
## CRLF preservation (file_operations.py)
Models nearly always send tool args with bare LF endings (JSON-encoded),
but the file on disk may have CRLF (Windows-line-ending configs, .bat,
.cmd, .ini files). Before this commit:
- write_file silently normalized CRLF to LF on every overwrite
- patch produced mixed-ending files: the substituted region had LF,
the surrounding context kept CRLF
The fix detects the file's existing line endings (via pre_content if
already read for lint/LSP, otherwise a tiny head -c 4096 probe), and
normalizes the entire write to that ending. New files are written
verbatim (no detection possible).
## Per-file failure escalation (file_tools.py)
When the agent fails to patch the same file 3+ times in a row, the
existing 'old_string not found' hint isn't strong enough — the model
keeps retrying with variations against a stale view of the file.
The fix tracks consecutive failures per (task_id, resolved_path) and
injects an escalating hint after 3 failures: 'This is failure #N
patching X. Stop retrying. Either re-read fresh, use longer context,
or fall back to write_file.' Counter resets on a successful patch to
the same path.
## Validation
- 22 new tests across tests/tools/test_fuzzy_match.py (5),
test_line_ending_preservation.py (12), test_patch_failure_tracking.py (5)
- All existing tests pass (165/165 in the touched files)
- E2E verified with real _handle_patch / _handle_write_file calls
against real CRLF files and real failure loops
Closes part of #507. The remaining open items in #507 (2b start_line
hint, behavioral rules) were declined after audit:
- 2b adds schema bloat for a problem the existing 'multiple matches'
contract already handles
- Behavioral rules conflict with the personality system
Items 1, 2d, 2e, 3, 4 of #507 were already landed in earlier work.
