The canalhandia PR review lost all findings because the agent ran out of
context before emitting the closing json fence. Three failure modes hit
the old regex \{.*?\}:
* nested objects inside the fence truncated at the first }
* bare arrays (no {summary, findings} wrapper) returned []
* unfenced JSON in the prose tail was never reached (first not last)
Replace the regex with a balanced-brace scanner:
* _last_json_block walks the fence contents with a depth counter so
nested objects survive
* _last_balanced_json + _balanced_json_substring handle bare arrays and
prose-tail JSON when no fence is present
* _parse_json_tolerant returns list as well as dict; parse_findings and
parse_review_output accept a bare array as the outer value
Agent prompt tightened: reserve the final step for emitting the JSON
block so the analysis isn't lost when context runs out.
10 new tests in tests/pilot/test_ai_review.py cover the new shapes.
Co-Authored-By: Claude <noreply@anthropic.com>
Two pure stdlib helpers that shrink what lands in the model prompt:
* compress_diff(diff, *, context=2) — re-renders a unified diff so each
hunk keeps only unchanged lines on either side of its +/- lines.
File headers + hunk headers + +/- lines preserved verbatim. Pure-context
hunks dropped (rare but legal — git emits them on whitespace-only diffs).
Collapsed gaps of >=5 lines emit a single '@@ … N context line(s) omitted
… @@' marker so the reviewer knows code was elided. Smaller gaps stay
silent — the marker would be longer than the elision.
* extract_finding_bullets(review_body) — pulls the lines of a prior review
that look like a pragent finding (- **[SEVERITY]** path:line — …) and
drops everything else. The model already has the diff; repeating the
prose is just token burn.
No I/O, no network. Tolerant of malformed input — never raises. 14 unit
tests cover both helpers, including an anchor-preservation check against
parse_diff_anchors to guarantee compress-then-anchor still works.
Wiring in ai_review/opencode_review lives in the next commit.
Marcos