support milestone and thrash rotation signals

internal/herdr/adapter.go

@@ -19,6 +19,9 @@ type Adapter interface {
 type TurnBoundary interface {
 	AtTurnBoundary(context.Context, Session) (bool, error)
 }
+type RotationSignal interface {
+	RotationSignal(context.Context, Session) (string, error)
+}
 type CLIAdapter struct {
 	Client  *Client
 	Harness string
@@ -58,6 +61,15 @@ func (a CLIAdapter) AtTurnBoundary(ctx context.Context, s Session) (bool, error)
 	}
 	return !IsBusy(r.Status), nil
 }
+func (a CLIAdapter) RotationSignal(ctx context.Context, s Session) (string, error) {
+	var r struct {
+		Reason string `json:"reason"`
+	}
+	if err := a.Client.Call(ctx, "pane.rotation_signal", s, &r); err != nil {
+		return "", err
+	}
+	return r.Reason, nil
+}
 func (a CLIAdapter) Occupancy(s Session) (float64, error) {
 	if a.Usage == nil {
 		return 0, fmt.Errorf("adapter: usage reader required")

internal/orchestrator/orchestrator.go

@@ -161,8 +161,14 @@ func (c *Coordinator) rotate(ctx context.Context, hard float64) {
 		if err != nil {
 			continue
 		}
+		reason := "threshold"
+		if signal, ok := a.(herdr.RotationSignal); ok {
+			if r, signalErr := signal.RotationSignal(ctx, session); signalErr == nil && r != "" {
+				reason = r
+			}
+		}
 		occupancy, err := a.Occupancy(session)
-		if err != nil || occupancy < hard {
+		if err != nil || (occupancy < hard && reason == "threshold") {
 			continue
 		}
 		if boundary, ok := a.(herdr.TurnBoundary); ok {
@@ -178,7 +184,7 @@ func (c *Coordinator) rotate(ctx context.Context, hard float64) {
 		if ref == "" {
 			continue
 		}
-		b, _ := json.Marshal(map[string]string{"handoff_ref": ref, "reason": "threshold"})
+		b, _ := json.Marshal(map[string]string{"handoff_ref": ref, "reason": reason})
 		e := domain.Event{ID: domain.NewID(), Type: "TaskReleased", TaskID: taskID, Version: task.Version + 1, Payload: b}
 		if c.Store.Append(e) == nil {
 			c.mu.Lock()

progress.md

@@ -75,6 +75,8 @@ Configured herdr `quota_limit` values are now wired into router availability usi
 
 Quota/standup scheduling now treats `QuotaReported` and `StandupAdvisory` as global events, adds `/v1/standup` read/request behavior, and emits one daily advisory during the 03:00 UTC safety window. Advisory contents include queued, leased, and blocked tasks.
 
+Harness adapters now expose optional `pane.rotation_signal` support for milestone/thrash triggers. The coordinator records the returned trigger reason in the handoff release and still requires a safe turn boundary before releasing.
+
 Recommended order:
 
 1. Add the orchestration coordinator: lease → worktree → harness session → bootstrap → lifecycle events.