feat(review): walkthrough/risk_verdict/test_coverage schema

pilot/opencode_review.py

@@ -905,6 +905,26 @@ def synthesize(
     return deduped[:per_pr_cap]
 
 
+def _synthesize_summary_fields(
+    findings: list[dict],
+    diff: str,
+    changed_paths: list[str] | None = None,
+) -> tuple[list[str], str, str]:
+    """Synthesize review-level meta from the merged findings + diff.
+
+    Returns (walkthrough, risk_verdict, test_coverage) — the three new
+    top-level fields in the pragent review JSON shape
+    (`ai_review.parse_review_output` extracts them as the 5th, 6th, and
+    7th tuple elements, defaulting to `[]` / `""` when missing).
+
+    STUB for Task 7. The real implementation arrives in Task 8; for now
+    every return is empty so the synthesized JSON shape stays parseable
+    and downstream tests that default the new fields to `[]` / `""`
+    continue to pass.
+    """
+    return [], "", ""
+
+
 # ---------------------------------------------------------------------------
 # Per-lens subprocess + parallel fan-out
 # ---------------------------------------------------------------------------
@@ -1304,10 +1324,25 @@ def run_lenses_review(
             {k: v for k, v in f.items() if not k.startswith("_")}
             for f in merged
         ]
+        # Synthesize the review-level meta (walkthrough / risk_verdict /
+        # test_coverage) from the merged findings + diff. Real implementation
+        # arrives in Task 8; the stub keeps the synthesized JSON shape stable
+        # so ai_review.parse_review_output can extract the three new fields
+        # (it defaults them to [] / "" when missing — backward compatible).
+        walkthrough, risk_verdict, test_coverage = _synthesize_summary_fields(
+            merged, diff, changed_paths=changed_paths,
+        )
+        synthesized_payload = {
+            "summary": summary,
+            "walkthrough": walkthrough,
+            "risk_verdict": risk_verdict,
+            "test_coverage": test_coverage,
+            "findings": clean_findings,
+        }
         text = (
             f"{summary}\n\n"
             f"## Findings (multi-lens)\n\n"
-            f"```json\n{json.dumps({'summary': summary, 'findings': clean_findings}, indent=2)}\n```\n"
+            f"```json\n{json.dumps(synthesized_payload, indent=2)}\n```\n"
         )
         if merged_usage is not None:
             merged_usage["duration_s"] = round(time.monotonic() - t0, 1)