Bound the wait for a handoff nobody answers

F62. The rotation is agent-driven: the worker asks, and the agent must write
its handoff. When the agent never does, renewals stopped on the ordinary
progress gate, the lease expired, and the task lost an attempt with nothing on
record saying a handoff had ever been requested. Run 16 showed only "agent
status idle and pane unchanged", 34 times.

The request is now stamped, and the wait around it is bounded. While Orchestra
is explicitly waiting the lease renews, because a quiet pane is the answer the
agent was told to give. The request is re-sent once after four minutes, with
the reason it was first asked with. At ten minutes the worker nacks with
failure class handoff_unanswered, and the coordinator releases the task naming
that cause instead of letting the lease die as generic idleness.

The class is known to DebtClassForFailureClass, so a harness that ignores
handoff requests accumulates as its own debt item rather than hiding inside
lease_expired.

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

internal/domain/debt.go

@@ -251,7 +251,7 @@ func DebtClassForBlockReason(r BlockReason) (DebtClass, bool) {
 // classes a worker actually emits are listed; an unknown one is not guessed at.
 func DebtClassForFailureClass(f string) (DebtClass, bool) {
 	switch f {
-	case "retry_limit", "launch_failed", "launch_transient", "launch_uncertain", "prompt_not_submitted", "lease_expired":
+	case "retry_limit", "launch_failed", "launch_transient", "launch_uncertain", "prompt_not_submitted", "lease_expired", "handoff_unanswered":
 		return DebtOperational, true
 	case "invalid_handoff":
 		return DebtCorrectness, true

internal/herdr/herdr.go

@@ -174,6 +174,14 @@ type Session struct {
 	// its §6.1 handoff (HandoffFile) — avoids re-sending the same prompt
 	// every tick while Release keeps waiting for the file to appear.
 	HandoffRequested bool `json:"handoff_requested,omitempty"`
+	// HandoffRequestedAt stamps that prompt. A request nobody answers used to
+	// end as an ordinary idle expiry, indistinguishable from an agent that
+	// never started (F62); the stamp is what makes the wait bounded and the
+	// giving-up causal.
+	HandoffRequestedAt time.Time `json:"handoff_requested_at,omitempty"`
+	// HandoffRetried records that the request was re-sent once, so a session
+	// waiting on an answer is not re-prompted every tick.
+	HandoffRetried bool `json:"handoff_retried,omitempty"`
 	// HandoffReason is selected by the coordinator when it asks for the
 	// semantic report. The checkout worker, rather than the harness, copies
 	// it into the canonical handoff it seals at release time.