A start failure after admission leaves a session running with no turn

internal/agents/manager.go

@@ -450,14 +450,17 @@ func (m *Manager) launch(ctx context.Context, sess api.AgentSession, task api.Ta
 		err = m.syncModel(ctx, l, sess.Model)
 	}
 	if err != nil {
-		serr := m.store.SetSessionState(ctx, sess.Id, api.AgentSessionStateIdle, actor, map[string]any{"error": err.Error()})
-		if serr != nil {
-			slog.Error("record failed start", "session", sess.Id, "err", serr)
-		}
+		m.failStart(ctx, sess.Id, actor, err)
 		return api.AgentSession{}, err
 	}
 
-	err = m.message(ctx, l, actor, text, images)
+	imgs, err := m.prepareMessage(ctx, l, actor, text, images)
+	if err != nil {
+		m.failStart(ctx, sess.Id, actor, err)
+		return api.AgentSession{}, err
+	}
+
+	err = l.sess.send(ctx, text, imgs)
 	if err != nil {
 		return api.AgentSession{}, err
 	}
@@ -465,6 +468,16 @@ func (m *Manager) launch(ctx context.Context, sess api.AgentSession, task api.Ta
 	return m.store.GetSession(ctx, sess.Id)
 }
 
+func (m *Manager) failStart(ctx context.Context, sessionID, actor string, err error) {
+	cctx, cancel := context.WithTimeout(context.WithoutCancel(ctx), 10*time.Second)
+	defer cancel()
+
+	serr := m.store.SetSessionState(cctx, sessionID, api.AgentSessionStateIdle, actor, map[string]any{"error": err.Error()})
+	if serr != nil {
+		slog.Error("record failed start", "session", sessionID, "err", serr)
+	}
+}
+
 func (m *Manager) syncModel(ctx context.Context, l *live, model string) error {
 	if model == l.model {
 		return nil
@@ -490,11 +503,19 @@ func transition(ctx context.Context, st *store.Store, id string, from, to api.Ag
 }
 
 func (m *Manager) message(ctx context.Context, l *live, actor, text string, images []string) error {
+	imgs, err := m.prepareMessage(ctx, l, actor, text, images)
+	if err != nil {
+		return err
+	}
+	return l.sess.send(ctx, text, imgs)
+}
+
+func (m *Manager) prepareMessage(ctx context.Context, l *live, actor, text string, images []string) ([]image, error) {
 	imgs := []image{}
 	for _, id := range images {
 		b, data, err := m.store.ReadBlob(ctx, id)
 		if err != nil {
-			return err
+			return nil, err
 		}
 		imgs = append(imgs, image{mediaType: b.ContentType, data: data})
 	}
@@ -503,7 +524,7 @@ func (m *Manager) message(ctx context.Context, l *live, actor, text string, imag
 	if l.implementer() {
 		head, err := git.Head(l.dir)
 		if err != nil {
-			return err
+			return nil, err
 		}
 		payload["head"] = head
 	}
@@ -519,7 +540,7 @@ func (m *Manager) message(ctx context.Context, l *live, actor, text string, imag
 	}
 	err := m.emit(ctx, l, actor, "user.message", payload)
 	if err != nil {
-		return err
+		return nil, err
 	}
 
 	m.mu.Lock()
@@ -532,7 +553,7 @@ func (m *Manager) message(ctx context.Context, l *live, actor, text string, imag
 	l.lastText = ""
 	m.mu.Unlock()
 
-	return l.sess.send(ctx, text, imgs)
+	return imgs, nil
 }
 
 func (m *Manager) ensureLive(ctx context.Context, sess api.AgentSession, task api.Task) (*live, error) {