ui: idea-timeline + pbi-link-card + download-md-button (M12 T-512)

components/ideas/idea-timeline.tsx:
- Chronological merge of IdeaLog + ClaudeQuestion (sorted desc by created_at)
- Per-entry icon by log-type (DECISION/NOTE/GRILL_RESULT/PLAN_RESULT/
  STATUS_CHANGE/JOB_EVENT) + question-status label
- MD3-tokens, vertical timeline rail (border-left + dots)
- Question entries show options + answer (border-left highlight)
- Metadata expansion via <details> for log entries

components/ideas/idea-pbi-link-card.tsx:
- PLANNED + pbi present: green status-done card with PBI link
- PLANNED + pbi removed (FK SetNull): blocked-color banner with
  "Plan opnieuw beschikbaar maken" → relinkIdeaPlanAction
- Demo blocked on relink

components/ideas/download-md-button.tsx:
- Calls downloadIdeaMdAction → builds Blob + anchor + click()
- Filename: {idea.code}-{kind}.md
- Demo MAY use it (read-only)

components/ideas/idea-detail-layout.tsx:
- Replaces inline placeholders with extracted components
- Md tabs gain Download (.md) button + Edit button row

Tests: 546/546 still green.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

components/ideas/download-md-button.tsx

@@ -0,0 +1,55 @@
+'use client'
+
+// DownloadMdButton — download grill_md of plan_md als .md-bestand.
+// Demo MAG downloaden (read-only). Server-action returnt md-string; client
+// bouwt een Blob + anchor + click().
+
+import { useTransition } from 'react'
+import { Download } from 'lucide-react'
+import { toast } from 'sonner'
+
+import { Button } from '@/components/ui/button'
+import { downloadIdeaMdAction } from '@/actions/ideas'
+
+interface Props {
+  ideaId: string
+  kind: 'grill' | 'plan'
+  hasContent: boolean
+}
+
+export function DownloadMdButton({ ideaId, kind, hasContent }: Props) {
+  const [pending, startTransition] = useTransition()
+
+  function handleClick() {
+    startTransition(async () => {
+      const r = await downloadIdeaMdAction(ideaId, kind)
+      if ('error' in r) {
+        toast.error(r.error)
+        return
+      }
+      if (!r.data) return
+      const blob = new Blob([r.data.markdown], { type: 'text/markdown;charset=utf-8' })
+      const url = URL.createObjectURL(blob)
+      const a = document.createElement('a')
+      a.href = url
+      a.download = r.data.filename
+      document.body.appendChild(a)
+      a.click()
+      a.remove()
+      URL.revokeObjectURL(url)
+    })
+  }
+
+  return (
+    <Button
+      size="sm"
+      variant="ghost"
+      onClick={handleClick}
+      disabled={pending || !hasContent}
+      title={hasContent ? `Download ${kind}_md` : 'Geen content'}
+    >
+      <Download className="size-3.5 mr-1" />
+      .md
+    </Button>
+  )
+}

components/ideas/idea-detail-layout.tsx

@@ -23,6 +23,9 @@ import type { IdeaDto } from '@/lib/idea-dto'
 import { updateIdeaAction, archiveIdeaAction } from '@/actions/ideas'
 import { IdeaRowActions } from '@/components/ideas/idea-row-actions'
 import { IdeaMdEditor } from '@/components/ideas/idea-md-editor'
+import { IdeaPbiLinkCard } from '@/components/ideas/idea-pbi-link-card'
+import { IdeaTimeline } from '@/components/ideas/idea-timeline'
+import { DownloadMdButton } from '@/components/ideas/download-md-button'
 
 const API_TO_DB: Record<IdeaStatusApi, Parameters<typeof getIdeaStatusBadge>[0]> = {
   draft: 'DRAFT',
@@ -153,32 +156,8 @@ export function IdeaDetailLayout({
         <IdeaRowActions idea={idea} isDemo={isDemo} onArchive={handleArchive} />
       </header>
 
-      {/* PBI-link card bij PLANNED — placeholder voor T-512 */}
-      {idea.status === 'planned' && idea.pbi && (
-        <div className="rounded-md border border-status-done/30 bg-status-done/10 p-4">
-          <p className="text-sm">
-            Gematerialiseerd als{' '}
-            <Link
-              href={
-                idea.product_id
-                  ? `/products/${idea.product_id}/backlog#pbi-${idea.pbi.code}`
-                  : '#'
-              }
-              className="font-medium text-status-done hover:underline"
-            >
-              {idea.pbi.code} — {idea.pbi.title}
-            </Link>
-          </p>
-        </div>
-      )}
-      {idea.status === 'planned' && !idea.pbi && (
-        <div className="rounded-md border border-status-blocked/30 bg-status-blocked/10 p-4 space-y-2">
-          <p className="text-sm">
-            De gekoppelde PBI bestaat niet meer. Klik om dit idee terug naar
-            <strong> PLAN_READY </strong>te zetten en opnieuw te materialiseren.
-          </p>
-        </div>
-      )}
+      {/* PBI-link card / Re-link banner bij PLANNED */}
+      <IdeaPbiLinkCard idea={idea} isDemo={isDemo} />
 
       {/* Tab-switcher */}
       <nav className="border-b border-input flex gap-1">
@@ -232,7 +211,7 @@ export function IdeaDetailLayout({
           ideaId={idea.id}
         />
       )}
-      {tab === 'timeline' && <TimelinePlaceholder logs={logs} questions={questions} />}
+      {tab === 'timeline' && <IdeaTimeline logs={logs} questions={questions} />}
     </div>
   )
 }
@@ -390,74 +369,17 @@ function MdSection({ kind, markdown, editable, ideaId }: MdProps) {
 
   return (
     <div className="space-y-3">
-      {editable && (
-        <div className="flex justify-end">
+      <div className="flex justify-end gap-2">
+        <DownloadMdButton ideaId={ideaId} kind={kind} hasContent={markdown !== null} />
+        {editable && (
           <Button size="sm" variant="outline" onClick={() => setEditing(true)}>
             Bewerk
           </Button>
-        </div>
-      )}
+        )}
+      </div>
       <pre className="rounded-md border border-input bg-surface-container p-4 text-sm whitespace-pre-wrap font-mono leading-relaxed overflow-x-auto">
         {markdown}
       </pre>
     </div>
   )
 }
-
-// ---------------------------------------------------------------------------
-// Timeline-placeholder. T-512 vervangt dit met de echte UNION-view.
-
-interface TimelineProps {
-  logs: IdeaLog[]
-  questions: IdeaQuestion[]
-}
-
-function TimelinePlaceholder({ logs, questions }: TimelineProps) {
-  const merged = [
-    ...logs.map((l) => ({
-      kind: 'log' as const,
-      created_at: l.created_at,
-      data: l,
-    })),
-    ...questions.map((q) => ({
-      kind: 'question' as const,
-      created_at: q.created_at,
-      data: q,
-    })),
-  ].sort((a, b) => (a.created_at < b.created_at ? 1 : -1))
-
-  if (merged.length === 0) {
-    return (
-      <p className="text-sm text-muted-foreground py-8 text-center italic">
-        Nog geen activiteit op dit idee.
-      </p>
-    )
-  }
-
-  return (
-    <ul className="space-y-3">
-      {merged.map((entry, i) => (
-        <li
-          key={`${entry.kind}-${i}`}
-          className="rounded-md border border-input bg-surface-container p-3"
-        >
-          <div className="flex items-center gap-2 text-xs text-muted-foreground">
-            <span className="font-mono uppercase">
-              {entry.kind === 'log' ? entry.data.type : `vraag · ${entry.data.status}`}
-            </span>
-            <span>·</span>
-            <time>{new Date(entry.created_at).toLocaleString()}</time>
-          </div>
-          <p className="mt-1 text-sm">
-            {entry.kind === 'log' ? entry.data.content : entry.data.question}
-          </p>
-          {entry.kind === 'question' && entry.data.answer && (
-            <p className="mt-1 text-sm text-muted-foreground border-l-2 border-primary pl-2">
-              {entry.data.answer}
-            </p>
-          )}
-        </li>
-      ))}
-    </ul>
-  )
-}

components/ideas/idea-pbi-link-card.tsx

@@ -0,0 +1,85 @@
+'use client'
+
+// IdeaPbiLinkCard — toont de gekoppelde PBI bij PLANNED. Bij "stale link"
+// (status===PLANNED maar pbi_id===null, want PBI elders verwijderd via
+// de SetNull FK) tonen we de Re-link-banner.
+
+import { useTransition } from 'react'
+import Link from 'next/link'
+import { useRouter } from 'next/navigation'
+import { ExternalLink, Link2Off } from 'lucide-react'
+import { toast } from 'sonner'
+
+import { Button } from '@/components/ui/button'
+import { relinkIdeaPlanAction } from '@/actions/ideas'
+import type { IdeaDto } from '@/lib/idea-dto'
+
+interface Props {
+  idea: IdeaDto
+  isDemo: boolean
+}
+
+export function IdeaPbiLinkCard({ idea, isDemo }: Props) {
+  const router = useRouter()
+  const [pending, startTransition] = useTransition()
+
+  if (idea.status !== 'planned') return null
+
+  if (idea.pbi && idea.product_id) {
+    return (
+      <div className="rounded-md border border-status-done/30 bg-status-done/10 p-4 flex items-center gap-3">
+        <div className="flex-1">
+          <p className="text-xs uppercase tracking-wide text-status-done font-medium">
+            Gepland
+          </p>
+          <p className="text-sm">
+            Gematerialiseerd als{' '}
+            <Link
+              href={`/products/${idea.product_id}/backlog#pbi-${idea.pbi.code}`}
+              className="font-medium text-status-done hover:underline inline-flex items-center gap-1"
+            >
+              {idea.pbi.code} — {idea.pbi.title}
+              <ExternalLink className="size-3" />
+            </Link>
+          </p>
+        </div>
+      </div>
+    )
+  }
+
+  // Stale link — pbi_id === null maar status nog PLANNED.
+  function handleRelink() {
+    if (isDemo) return
+    startTransition(async () => {
+      const r = await relinkIdeaPlanAction(idea.id)
+      if ('error' in r) {
+        toast.error(r.error)
+        return
+      }
+      toast.success('Idee terug naar PLAN_READY — open de Plan-tab.')
+      router.refresh()
+    })
+  }
+
+  return (
+    <div className="rounded-md border border-status-blocked/30 bg-status-blocked/10 p-4 space-y-2">
+      <div className="flex items-center gap-2">
+        <Link2Off className="size-4 text-status-blocked" />
+        <p className="text-sm font-medium text-status-blocked">
+          De gekoppelde PBI bestaat niet meer
+        </p>
+      </div>
+      <p className="text-sm text-muted-foreground">
+        Klik om dit idee terug naar PLAN_READY te zetten en opnieuw te materialiseren.
+      </p>
+      <Button
+        size="sm"
+        variant="outline"
+        onClick={handleRelink}
+        disabled={isDemo || pending}
+      >
+        Plan opnieuw beschikbaar maken
+      </Button>
+    </div>
+  )
+}

components/ideas/idea-timeline.tsx

@@ -0,0 +1,163 @@
+'use client'
+
+// IdeaTimeline — chronologische merge van IdeaLog + ClaudeQuestion entries.
+// Server-component zou ook kunnen, maar we mounten dit binnen de client-side
+// detail-layout dus client is simpler (geen rsc-boundary doorbreken).
+//
+// Iconen + kleur per log-type voor snelle herkenning.
+
+import {
+  ClipboardList,
+  FileText,
+  HelpCircle,
+  Lightbulb,
+  RefreshCw,
+  StickyNote,
+  Wrench,
+} from 'lucide-react'
+
+import type { IdeaLogType } from '@prisma/client'
+
+export interface TimelineLog {
+  id: string
+  type: string
+  content: string
+  metadata: unknown
+  created_at: string
+}
+
+export interface TimelineQuestion {
+  id: string
+  question: string
+  options: string[] | null
+  status: 'open' | 'answered' | 'cancelled' | 'expired'
+  answer: string | null
+  created_at: string
+  expires_at: string
+}
+
+interface Props {
+  logs: TimelineLog[]
+  questions: TimelineQuestion[]
+}
+
+const LOG_ICON: Record<IdeaLogType, React.ReactNode> = {
+  DECISION: <Lightbulb className="size-4" />,
+  NOTE: <StickyNote className="size-4" />,
+  GRILL_RESULT: <FileText className="size-4" />,
+  PLAN_RESULT: <ClipboardList className="size-4" />,
+  STATUS_CHANGE: <RefreshCw className="size-4" />,
+  JOB_EVENT: <Wrench className="size-4" />,
+}
+
+const LOG_LABEL: Record<IdeaLogType, string> = {
+  DECISION: 'Beslissing',
+  NOTE: 'Notitie',
+  GRILL_RESULT: 'Grill-resultaat',
+  PLAN_RESULT: 'Plan-resultaat',
+  STATUS_CHANGE: 'Status',
+  JOB_EVENT: 'Job-event',
+}
+
+const QUESTION_STATUS_LABEL: Record<TimelineQuestion['status'], string> = {
+  open: 'Open',
+  answered: 'Beantwoord',
+  cancelled: 'Geannuleerd',
+  expired: 'Verlopen',
+}
+
+export function IdeaTimeline({ logs, questions }: Props) {
+  const merged = [
+    ...logs.map((l) => ({
+      kind: 'log' as const,
+      created_at: l.created_at,
+      data: l,
+    })),
+    ...questions.map((q) => ({
+      kind: 'question' as const,
+      created_at: q.created_at,
+      data: q,
+    })),
+  ].sort((a, b) => (a.created_at < b.created_at ? 1 : -1))
+
+  if (merged.length === 0) {
+    return (
+      <p className="text-sm text-muted-foreground py-8 text-center italic">
+        Nog geen activiteit op dit idee.
+      </p>
+    )
+  }
+
+  return (
+    <ol className="border-l-2 border-input pl-4 space-y-3 ml-2">
+      {merged.map((entry, i) => {
+        const time = new Date(entry.created_at).toLocaleString()
+
+        if (entry.kind === 'log') {
+          const type = entry.data.type as IdeaLogType
+          return (
+            <li key={`l-${entry.data.id}`} className="relative">
+              <span className="absolute -left-[26px] top-1 flex size-5 items-center justify-center rounded-full bg-surface-container text-muted-foreground">
+                {LOG_ICON[type] ?? <StickyNote className="size-4" />}
+              </span>
+              <div className="rounded-md border border-input bg-surface-container p-3 space-y-1">
+                <div className="flex items-center gap-2 text-xs text-muted-foreground">
+                  <span className="font-medium uppercase tracking-wide">
+                    {LOG_LABEL[type] ?? type}
+                  </span>
+                  <span>·</span>
+                  <time>{time}</time>
+                </div>
+                <p className="text-sm whitespace-pre-wrap">{entry.data.content}</p>
+                {entry.data.metadata != null &&
+                typeof entry.data.metadata === 'object' &&
+                Object.keys(entry.data.metadata as object).length > 0 ? (
+                  <details className="text-xs text-muted-foreground">
+                    <summary className="cursor-pointer">metadata</summary>
+                    <pre className="mt-1 whitespace-pre-wrap font-mono text-[10px]">
+                      {JSON.stringify(entry.data.metadata, null, 2)}
+                    </pre>
+                  </details>
+                ) : null}
+              </div>
+            </li>
+          )
+        }
+
+        const q = entry.data
+        return (
+          <li key={`q-${q.id}-${i}`} className="relative">
+            <span className="absolute -left-[26px] top-1 flex size-5 items-center justify-center rounded-full bg-surface-container text-status-review">
+              <HelpCircle 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">Vraag</span>
+                <span>·</span>
+                <span>{QUESTION_STATUS_LABEL[q.status]}</span>
+                <span>·</span>
+                <time>{time}</time>
+              </div>
+              <p className="text-sm">{q.question}</p>
+              {q.options && q.options.length > 0 ? (
+                <ul className="text-xs text-muted-foreground list-disc list-inside">
+                  {q.options.map((o, ii) => (
+                    <li key={ii}>{o}</li>
+                  ))}
+                </ul>
+              ) : null}
+              {q.answer ? (
+                <p className="text-sm border-l-2 border-primary pl-2 text-foreground">
+                  <span className="text-xs font-medium uppercase tracking-wide text-primary mr-2">
+                    Antwoord
+                  </span>
+                  {q.answer}
+                </p>
+              ) : null}
+            </div>
+          </li>
+        )
+      })}
+    </ol>
+  )
+}