fix(review): address round-2 review issues

- Remove unused `cwd` param from reviewDiffWithAgent()
- Fix JSON extraction: use indexOf/lastIndexOf instead of regex
  (handles braces in strings correctly)
- Add task.error message when review rejects merge
- Add review_started event assertions to scheduler tests

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: robotlearning123

src/__tests__/agent-runner.test.ts

@@ -423,7 +423,6 @@ describe("AgentRunner", () => {
     const result = await runner.reviewDiffWithAgent(
       "diff --git a/foo.test.ts b/foo.test.ts\n+it('works', () => {});",
       "claude",  // task was by claude → review by codex → codex fails → fallback
-      "/tmp",
       2,  // 2 second timeout to keep test fast
     );
     assert.strictEqual(typeof result.approve, "boolean");

src/__tests__/scheduler.test.ts

@@ -897,8 +897,11 @@ describe("Scheduler", () => {
       assert.ok(task.review);
       assert.strictEqual(task.review!.approve, false);
       assert.strictEqual(task.review!.score, 25);
-      // Should have emitted review_rejected event
-      assert.ok(events.some(e => e.type === "review_rejected"));
+      // Error should explain why merge was blocked
+      assert.ok(task.error.includes("review rejected"), "error should explain rejection");
+      // Should have emitted review_started and review_rejected events
+      assert.ok(events.some(e => e.type === "review_started"), "should emit review_started");
+      assert.ok(events.some(e => e.type === "review_rejected"), "should emit review_rejected");
     });
 
     it("review gate allows merge when review approves", async () => {
@@ -942,7 +945,8 @@ describe("Scheduler", () => {
       assert.strictEqual(mergeCalledWith, true);
       assert.ok(task.review);
       assert.strictEqual(task.review!.approve, true);
-      assert.ok(events.some(e => e.type === "review_approved"));
+      assert.ok(events.some(e => e.type === "review_started"), "should emit review_started");
+      assert.ok(events.some(e => e.type === "review_approved"), "should emit review_approved");
     });
 
     it("skips review when task has no diff", async () => {

src/agent-runner.ts

@@ -112,7 +112,6 @@ export class AgentRunner {
   async reviewDiffWithAgent(
     diff: string,
     taskAgent: string,
-    cwd: string,
     timeout: number = 60,
   ): Promise<ReviewResult> {
     const reviewAgent = AgentRunner.pickReviewAgent(taskAgent);
@@ -194,12 +193,12 @@ export class AgentRunner {
       }
     } catch { /* not pure JSON */ }
 
-    // Try to find JSON object in the output (agent may wrap it in text)
-    // Use [^{}]* to avoid greedily matching across multiple JSON objects
-    const candidates = [...output.matchAll(/\{[^{}]*"approve"\s*:\s*(true|false)[^{}]*\}/g)];
-    for (const match of candidates) {
+    // Try to extract JSON by finding the outermost { } that contains "approve"
+    const start = output.indexOf("{");
+    const end = output.lastIndexOf("}");
+    if (start !== -1 && end > start) {
       try {
-        const obj = JSON.parse(match[0]);
+        const obj = JSON.parse(output.slice(start, end + 1));
         if (typeof obj.approve === "boolean" && typeof obj.score === "number") {
           return {
             approve: obj.approve,
@@ -208,7 +207,7 @@ export class AgentRunner {
             suggestions: Array.isArray(obj.suggestions) ? obj.suggestions.map(String) : [],
           };
         }
-      } catch { /* try next candidate */ }
+      } catch { /* not valid JSON */ }
     }
 
     return null;

src/scheduler.ts

@@ -480,10 +480,11 @@ export class Scheduler {
           const taskAgent = task.agent ?? "claude";
           const reviewAgent = AgentRunner.pickReviewAgent(taskAgent);
           this.onEvent?.({ type: "review_started", taskId: task.id, reviewAgent });
-          const review = await this.runner.reviewDiffWithAgent(diff, taskAgent, workerPath);
+          const review = await this.runner.reviewDiffWithAgent(diff, taskAgent);
           task.review = review;
           if (!review.approve) {
             shouldMerge = false;
+            task.error = `review rejected (score ${review.score}): ${review.issues.join("; ")}`;
             log("info", "cross-agent review rejected merge", {
               taskId: task.id,
               score: review.score,