feat(ST-0vtnydpi): Chat & Timeline tab — userQuestion rendering + UserChatInput

- IdeaTimeline: merge user_question entries into timeline (MessageCircle icon,
  pending/answered states); show UserChatInput below ol when planMd present
- UserChatInput: Textarea + submit button calling createUserQuestionAction,
  router.refresh() on success, sonner toast for errors
- IdeaDetailLayout: rename tab label to 'Chat & Timeline'; pass userQuestions,
  planMd, ideaId props to IdeaTimeline; export IdeaUserQuestionDto interface

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

components/ideas/idea-detail-layout.tsx

@@ -44,7 +44,7 @@ const TABS: { key: TabKey; label: string }[] = [
   { key: 'idee', label: 'Idee' },
   { key: 'grill', label: 'Grill' },
   { key: 'plan', label: 'Plan' },
-  { key: 'timeline', label: 'Timeline' },
+  { key: 'timeline', label: 'Chat & Timeline' },
 ]
 
 interface IdeaLog {
@@ -221,7 +221,15 @@ export function IdeaDetailLayout({
           ideaId={idea.id}
         />
       )}
-      {tab === 'timeline' && <IdeaTimeline logs={logs} questions={questions} />}
+      {tab === 'timeline' && (
+        <IdeaTimeline
+          logs={logs}
+          questions={questions}
+          userQuestions={userQuestions}
+          planMd={plan_md}
+          ideaId={idea.id}
+        />
+      )}
     </div>
   )
 }

components/ideas/idea-timeline.tsx

@@ -15,6 +15,7 @@ import {
   FileText,
   HelpCircle,
   Lightbulb,
+  MessageCircle,
   RefreshCw,
   StickyNote,
   Wrench,
@@ -24,6 +25,7 @@ import { toast } from 'sonner'
 import { Button } from '@/components/ui/button'
 import { Textarea } from '@/components/ui/textarea'
 import { answerQuestion } from '@/actions/questions'
+import { createUserQuestionAction } from '@/actions/user-questions'
 
 import type { IdeaLogType } from '@prisma/client'
 
@@ -45,9 +47,20 @@ export interface TimelineQuestion {
   expires_at: string
 }
 
+export interface TimelineUserQuestion {
+  id: string
+  question: string
+  answer: string | null
+  status: 'pending' | 'answered'
+  created_at: string
+}
+
 interface Props {
   logs: TimelineLog[]
   questions: TimelineQuestion[]
+  userQuestions: TimelineUserQuestion[]
+  planMd: string | null
+  ideaId: string
 }
 
 const LOG_ICON: Record<IdeaLogType, React.ReactNode> = {
@@ -75,7 +88,7 @@ const QUESTION_STATUS_LABEL: Record<TimelineQuestion['status'], string> = {
   expired: 'Verlopen',
 }
 
-export function IdeaTimeline({ logs, questions }: Props) {
+export function IdeaTimeline({ logs, questions, userQuestions, planMd, ideaId }: Props) {
   const merged = [
     ...logs.map((l) => ({
       kind: 'log' as const,
@@ -87,9 +100,14 @@ export function IdeaTimeline({ logs, questions }: Props) {
       created_at: q.created_at,
       data: q,
     })),
+    ...userQuestions.map((uq) => ({
+      kind: 'user_question' as const,
+      created_at: uq.created_at,
+      data: uq,
+    })),
   ].sort((a, b) => (a.created_at < b.created_at ? 1 : -1))
 
-  if (merged.length === 0) {
+  if (merged.length === 0 && !planMd) {
     return (
       <p className="text-sm text-muted-foreground py-8 text-center italic">
         Nog geen activiteit op dit idee.
@@ -98,6 +116,7 @@ export function IdeaTimeline({ logs, questions }: Props) {
   }
 
   return (
+    <div>
     <ol className="border-l-2 border-input pl-4 space-y-3 ml-2">
       {merged.map((entry, i) => {
         // Expliciete locale + format om SSR/CSR hydration-mismatch te voorkomen
@@ -138,6 +157,37 @@ export function IdeaTimeline({ logs, questions }: Props) {
           )
         }
 
+        if (entry.kind === 'user_question') {
+          const uq = entry.data
+          return (
+            <li key={`uq-${uq.id}-${i}`} className="relative">
+              <span className="absolute -left-[26px] top-1 flex size-5 items-center justify-center rounded-full bg-surface-container text-primary">
+                <MessageCircle className="size-4" />
+              </span>
+              <div className="rounded-md border border-input bg-surface-container p-3 space-y-2">
+                <div className="flex items-center gap-2 text-xs text-muted-foreground">
+                  <span className="font-medium uppercase tracking-wide">Jouw vraag</span>
+                  <span>·</span>
+                  <time>{time}</time>
+                </div>
+                <p className="text-sm">{uq.question}</p>
+                {uq.status === 'pending' ? (
+                  <p className="text-xs text-muted-foreground italic">
+                    Wacht op antwoord van Claude...
+                  </p>
+                ) : uq.answer ? (
+                  <div className="mt-2 rounded bg-muted/50 p-3 text-sm">
+                    <span className="text-xs font-medium uppercase tracking-wide text-primary mr-2">
+                      Claude
+                    </span>
+                    {uq.answer}
+                  </div>
+                ) : null}
+              </div>
+            </li>
+          )
+        }
+
         const q = entry.data
         return (
           <li key={`q-${q.id}-${i}`} className="relative">
@@ -179,6 +229,12 @@ export function IdeaTimeline({ logs, questions }: Props) {
         )
       })}
     </ol>
+    {planMd && (
+      <div className="mt-4 border-t pt-4">
+        <UserChatInput ideaId={ideaId} />
+      </div>
+    )}
+    </div>
   )
 }
 
@@ -269,3 +325,47 @@ function AnswerForm({
     </div>
   )
 }
+
+// ---------------------------------------------------------------------------
+// UserChatInput — stel een vraag aan Claude over het plan van dit idee.
+
+function UserChatInput({ ideaId }: { ideaId: string }) {
+  const router = useRouter()
+  const [question, setQuestion] = useState('')
+  const [isPending, startTransition] = useTransition()
+
+  function submit() {
+    const trimmed = question.trim()
+    if (!trimmed) return
+    startTransition(async () => {
+      const res = await createUserQuestionAction(ideaId, trimmed)
+      if ('success' in res && res.success) {
+        setQuestion('')
+        toast.success('Vraag verstuurd — Claude antwoordt zodra mogelijk.')
+        router.refresh()
+      } else if ('error' in res) {
+        toast.error(res.error)
+      }
+    })
+  }
+
+  return (
+    <div className="space-y-2">
+      <p className="text-xs font-medium text-muted-foreground uppercase tracking-wide">
+        Stel een vraag aan Claude
+      </p>
+      <Textarea
+        value={question}
+        onChange={(e) => setQuestion(e.target.value)}
+        rows={3}
+        placeholder="Vraag iets over het plan…"
+        disabled={isPending}
+      />
+      <div className="flex justify-end">
+        <Button size="sm" disabled={isPending || !question.trim()} onClick={submit}>
+          Vraag stellen
+        </Button>
+      </div>
+    </div>
+  )
+}