Stop refusing a handoff over words the arrow already says

98f1b2d fixed the arrow and left the other half. "tried" and "failed because"
restate the field names either side of a separator that already says what the
line means, and the parser required both.

Run 9 lost three leases to this. Every refused line carried exactly the data
the fields want:

    tried run line ["bash", "scripts/test_healthcheck.sh"] for phase-3
      -> refused, policy allows only bash -n on one file
    tried finding ids "F1".."F8" in research.json
      -> schema requires lowercase letters, digits, dash or underscore

Both prefixes are now optional. A line with no cause and effect is still
refused, because the split is the thing being validated.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01CVbaKucEYBjMqVeUgJUsc1

internal/herdr/adapter.go

@@ -198,7 +198,7 @@ const handoffPrompt = `Orchestra is about to rotate this task. Write ONLY the fo
 NEXT: the single next action (one line, at most 200 characters).
 WHY: why that is next (one line, at most 200 characters).
 REMAINING: outstanding items, one line each, at most 200 characters each. If none: NONE.
-DEAD ENDS: approaches tried that failed — "tried X → failed because Y", one per line ("->" is also accepted). If none: NONE.
+DEAD ENDS: approaches tried that failed — "X → why it failed", one per line. Either arrow, and the words "tried"/"failed because" are optional. If none: NONE.
 OPEN Q: unresolved decisions, one line each. If none: NONE.
 LEARNED: constraints discovered that are NOT in TASK.md, one line each. If none: NONE.
 
@@ -511,12 +511,13 @@ func parseHandoffAnswer(answer string) (handoffAnswer, error) {
 		if len(parts) != 2 {
 			return out, fmt.Errorf("DEAD ENDS: want 'tried X → failed because Y'")
 		}
-		left, right := strings.TrimSpace(parts[0]), strings.TrimSpace(parts[1])
-		if !strings.HasPrefix(left, "tried ") || !strings.HasPrefix(right, "failed because ") {
-			return out, fmt.Errorf("DEAD ENDS: want 'tried X → failed because Y'")
-		}
-		tried := strings.TrimSpace(strings.TrimPrefix(left, "tried "))
-		why := strings.TrimSpace(strings.TrimPrefix(right, "failed because "))
+		// Both prefixes are optional. "tried" and "failed because" restate the
+		// field names either side of an arrow that already says what the line
+		// means, and run 9 lost three leases to an agent that dropped them
+		// while writing exactly the right content. What must be there is a
+		// cause and an effect, which is what the split establishes.
+		tried := strings.TrimSpace(strings.TrimPrefix(strings.TrimSpace(parts[0]), "tried "))
+		why := strings.TrimSpace(strings.TrimPrefix(strings.TrimSpace(parts[1]), "failed because "))
 		if tried == "" || why == "" {
 			return out, fmt.Errorf("DEAD ENDS: want 'tried X → failed because Y'")
 		}

internal/herdr/adapter_test.go

@@ -366,30 +366,45 @@ func TestLastObservedCommandSkipsOrchestrasOwnHandoffWrite(t *testing.T) {
 	}
 }
 
-// Run 9 lost a lease because the agent wrote "->" instead of "→". The content
-// was exactly right, the handoff was refused, and a refused handoff fails the
-// release rather than the turn.
-func TestDeadEndAcceptsEitherArrowAndStripsThePrefixes(t *testing.T) {
-	for _, arrow := range []string{"→", "->"} {
+// Run 9 lost three leases to a handoff whose content was exactly right. The
+// agent wrote "->" for the arrow and dropped the "tried"/"failed because"
+// words, and each refusal failed the release rather than the turn.
+func TestDeadEndAcceptsEitherArrowAndOptionalPrefixes(t *testing.T) {
+	for _, line := range []string{
+		`tried finding ids "F1".."F8" → failed because the schema requires lowercase`,
+		`tried finding ids "F1".."F8" -> failed because the schema requires lowercase`,
+		`finding ids "F1".."F8" -> the schema requires lowercase`,
+		`tried finding ids "F1".."F8" -> the schema requires lowercase`,
+	} {
 		a, err := parseHandoffAnswer(`NEXT: inspect the failing integration test
 WHY: isolate the regression before changing production code
 REMAINING: fix the assertion after identifying the cause
-DEAD ENDS: tried finding ids "F1".."F8" ` + arrow + ` failed because the schema requires lowercase
+DEAD ENDS: ` + line + `
 OPEN Q: whether the remote worker has the updated fixture
 LEARNED: the fixture requires a committed scratch branch
 `)
 		if err != nil {
-			t.Fatalf("arrow %q: %v", arrow, err)
+			t.Fatalf("%q: %v", line, err)
 		}
 		if len(a.DeadEnds) != 1 {
-			t.Fatalf("arrow %q: parsed %d dead ends", arrow, len(a.DeadEnds))
+			t.Fatalf("%q: parsed %d dead ends", line, len(a.DeadEnds))
 		}
 		d := a.DeadEnds[0]
 		if d.Tried != `finding ids "F1".."F8"` {
-			t.Errorf("arrow %q: tried = %q", arrow, d.Tried)
+			t.Errorf("%q: tried = %q", line, d.Tried)
 		}
 		if d.WhyFailed != "the schema requires lowercase" {
-			t.Errorf("arrow %q: why_failed = %q", arrow, d.WhyFailed)
+			t.Errorf("%q: why_failed = %q", line, d.WhyFailed)
 		}
 	}
+	// A line with no cause and effect at all is still refused.
+	if _, err := parseHandoffAnswer(`NEXT: a
+WHY: b
+REMAINING: c
+DEAD ENDS: this line names no outcome
+OPEN Q: d
+LEARNED: e
+`); err == nil {
+		t.Error("a dead end with no separator was accepted")
+	}
 }