Renew a lease only when the agent shows progress

renewLeases renewed whenever a session existed and PaneCapture succeeded,
so a pane that opened and never accepted a prompt held its lease forever.
That is the mechanism behind the July stuck task: the launch failed and
nothing ever let go.

Renewal now needs the agent to be busy, or the pane capture to differ from
the one recorded at the previous renewal. The first renewal has no baseline,
so it records one and passes; the next must show movement.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

cmd/orchestra-worker/main_test.go

@@ -371,6 +371,7 @@ func mustJSON(v any) []byte { b, _ := json.Marshal(v); return b }
 
 type recordingBackend struct {
 	status  string
+	capture string
 	calls   []string
 	prompts []string
 }
@@ -395,7 +396,43 @@ func (b *recordingBackend) AgentStatus(context.Context, herdr.Session) (string,
 	return b.status, nil
 }
 func (b *recordingBackend) PaneCapture(context.Context, herdr.Session, string) (string, error) {
-	return "", nil
+	return b.capture, nil
+}
+
+func TestRenewLeasesRequiresProgress(t *testing.T) {
+	renewals := 0
+	api := httptest.NewServer(http.HandlerFunc(func(rw http.ResponseWriter, r *http.Request) {
+		renewals++
+		rw.Write([]byte(`{}`))
+	}))
+	defer api.Close()
+	backend := &recordingBackend{status: "idle", capture: "same screen"}
+	w := &worker{
+		api:         federation.Client{BaseURL: api.URL, WorkerID: "h", Token: "t"},
+		backend:     backend,
+		harness:     "claude",
+		sessions:    map[string]herdr.Session{"task": {PaneID: "pane"}},
+		leases:      map[string]lease{"task": {Epoch: "e", Version: 1, Until: time.Now(), ProgressSHA: domain.Hash([]byte("same screen"))}},
+		quarantined: map[string]bool{},
+		statePath:   filepath.Join(t.TempDir(), "state.json"),
+	}
+	w.renewLeases(context.Background())
+	if renewals != 0 {
+		t.Fatalf("idle pane with an unchanged capture renewed its lease %d times", renewals)
+	}
+	backend.status = "busy"
+	w.renewLeases(context.Background())
+	if renewals != 1 {
+		t.Fatalf("busy agent renewals=%d, want 1", renewals)
+	}
+	backend.status, backend.capture = "idle", "new output"
+	l := w.leases["task"]
+	l.Until = time.Now()
+	w.leases["task"] = l
+	w.renewLeases(context.Background())
+	if renewals != 2 {
+		t.Fatalf("changed capture renewals=%d, want 2", renewals)
+	}
 }
 func (b *recordingBackend) SendText(_ context.Context, _ herdr.Session, text string) error {
 	b.calls = append(b.calls, "text:"+text)