fix: task lane no longer self-hides on submit

TaskLane had `if (submitted) return null` which immediately hid the
component after submit, before the AI could respond. Now the parent
controls visibility: the lane stays visible during the AI call, then
either updates with new tasks or clears when the AI sends none.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

frontend/src/components/assistant/TaskLane.tsx

@@ -50,7 +50,6 @@ export function TaskLane({ questions, actions, onSubmit, onClose, loading }: Tas
     })),
   ])
   const [submitting, setSubmitting] = useState(false)
-  const [submitted, setSubmitted] = useState(false)
   const [showRunAll, setShowRunAll] = useState(false)
   const [showPreview, setShowPreview] = useState(false)
 
@@ -112,7 +111,6 @@ export function TaskLane({ questions, actions, onSubmit, onClose, loading }: Tas
         type: 'action', label: a.label, command: a.command, description: a.description, state: 'pending', value: '',
       })),
     ])
-    setSubmitted(false)
   }, [questions, actions])
 
   const updateTask = (idx: number, updates: Partial<TaskResponse>) => {
@@ -164,12 +162,12 @@ export function TaskLane({ questions, actions, onSubmit, onClose, loading }: Tas
   const handleSubmit = () => {
     setSubmitting(true)
     onSubmit(tasks)
-    setSubmitted(true)
+    // Don't self-hide — parent controls visibility via showTaskLane.
+    // The AI response will either send updated tasks (replacing these)
+    // or send none (parent hides the lane).
     setSubmitting(false)
   }
 
-  if (submitted) return null
-
   return (
     <div
       className="relative bg-sidebar border-l border-default flex flex-col shrink-0 animate-in slide-in-from-right-4 duration-200"

frontend/src/pages/AssistantChatPage.tsx

@@ -310,13 +310,18 @@ export default function AssistantChatPage() {
       if (response.fork && activeChatId) {
         branching.loadBranches(activeChatId)
       }
-      // Show task lane again if AI sends more tasks
+      // Update task lane based on AI response
       const hasQuestions = response.questions && response.questions.length > 0
       const hasActions = response.actions && response.actions.length > 0
       if (hasQuestions || hasActions) {
         setActiveQuestions(response.questions || [])
         setActiveActions(response.actions || [])
         setShowTaskLane(true)
+      } else {
+        // AI sent no new tasks — clear the lane
+        setShowTaskLane(false)
+        setActiveQuestions([])
+        setActiveActions([])
       }
     } catch {
       setMessages(prev => [