Add GT button to OCR overlay, prominent category picker, track pipeline

- Ground Truth button on last step of Pipeline/Kombi modes in ocr-overlay
- Prominent category picker in active session info bar (pulses when unset)
- GT badge shown when session has ground truth reference
- Backend: auto-detect pipeline from ocr_engine, store in GT snapshot
- Pipeline info shown in GT session list and regression reports
- Also pass pipeline param from ocr-pipeline StepGroundTruth

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

admin-lehrer/app/(admin)/ai/ocr-overlay/page.tsx

@@ -28,6 +28,10 @@ export default function OcrOverlayPage() {
   const [editNameValue, setEditNameValue] = useState('')
   const [editingCategory, setEditingCategory] = useState<string | null>(null)
   const [activeCategory, setActiveCategory] = useState<DocumentCategory | undefined>(undefined)
+  const [editingActiveCategory, setEditingActiveCategory] = useState(false)
+  const [isGroundTruth, setIsGroundTruth] = useState(false)
+  const [gtSaving, setGtSaving] = useState(false)
+  const [gtMessage, setGtMessage] = useState('')
   const [steps, setSteps] = useState<PipelineStep[]>(
     OVERLAY_PIPELINE_STEPS.map((s, i) => ({
       ...s,
@@ -64,6 +68,8 @@ export default function OcrOverlayPage() {
       setSessionId(sid)
       setSessionName(data.name || data.filename || '')
       setActiveCategory(data.document_category || undefined)
+      setIsGroundTruth(!!data.ground_truth?.build_grid_reference)
+      setGtMessage('')
 
       // Check if this session was processed with paddle_direct, kombi, or rapid_kombi
       const ocrEngine = data.word_result?.ocr_engine
@@ -239,6 +245,33 @@ export default function OcrOverlayPage() {
   // eslint-disable-next-line react-hooks/exhaustive-deps
   }, [sessionId, goToStep])
 
+  const handleMarkGroundTruth = async () => {
+    if (!sessionId) return
+    setGtSaving(true)
+    setGtMessage('')
+    try {
+      const resp = await fetch(
+        `${KLAUSUR_API}/api/v1/ocr-pipeline/sessions/${sessionId}/mark-ground-truth?pipeline=${mode}`,
+        { method: 'POST' }
+      )
+      if (!resp.ok) {
+        const body = await resp.text().catch(() => '')
+        throw new Error(`Ground Truth fehlgeschlagen (${resp.status}): ${body}`)
+      }
+      const data = await resp.json()
+      setIsGroundTruth(true)
+      setGtMessage(`Ground Truth gespeichert (${data.cells_saved} Zellen)`)
+      setTimeout(() => setGtMessage(''), 5000)
+    } catch (e) {
+      setGtMessage(e instanceof Error ? e.message : String(e))
+    } finally {
+      setGtSaving(false)
+    }
+  }
+
+  const isLastStep = currentStep === steps.length - 1
+  const showGtButton = isLastStep && sessionId != null
+
   const renderStep = () => {
     if (mode === 'paddle-direct' || mode === 'kombi') {
       switch (currentStep) {
@@ -472,14 +505,48 @@ export default function OcrOverlayPage() {
         )}
       </div>
 
-      {/* Active session info */}
+      {/* Active session info + category picker */}
       {sessionId && sessionName && (
-        <div className="flex items-center gap-3 text-sm text-gray-500 dark:text-gray-400">
+        <div className="relative flex items-center gap-3 text-sm text-gray-500 dark:text-gray-400">
           <span>Aktive Session: <span className="font-medium text-gray-700 dark:text-gray-300">{sessionName}</span></span>
-          {activeCategory && (() => {
-            const cat = DOCUMENT_CATEGORIES.find(c => c.value === activeCategory)
-            return cat ? <span className="text-xs px-2 py-0.5 rounded-full bg-teal-50 dark:bg-teal-900/30 border border-teal-200 dark:border-teal-700 text-teal-700 dark:text-teal-300">{cat.icon} {cat.label}</span> : null
-          })()}
+          <button
+            onClick={() => setEditingActiveCategory(!editingActiveCategory)}
+            className={`text-xs px-2.5 py-1 rounded-full border transition-colors ${
+              activeCategory
+                ? 'bg-teal-50 dark:bg-teal-900/30 border-teal-200 dark:border-teal-700 text-teal-700 dark:text-teal-300 hover:bg-teal-100 dark:hover:bg-teal-900/50'
+                : 'bg-amber-50 dark:bg-amber-900/20 border-amber-300 dark:border-amber-700 text-amber-700 dark:text-amber-300 hover:bg-amber-100 dark:hover:bg-amber-900/40 animate-pulse'
+            }`}
+          >
+            {activeCategory ? (() => {
+              const cat = DOCUMENT_CATEGORIES.find(c => c.value === activeCategory)
+              return cat ? `${cat.icon} ${cat.label}` : activeCategory
+            })() : 'Kategorie setzen'}
+          </button>
+          {isGroundTruth && (
+            <span className="text-xs px-2 py-0.5 rounded-full bg-amber-50 dark:bg-amber-900/20 border border-amber-300 dark:border-amber-700 text-amber-700 dark:text-amber-300">
+              GT
+            </span>
+          )}
+          {editingActiveCategory && (
+            <div className="absolute left-0 top-full mt-1 z-20 bg-white dark:bg-gray-800 border border-gray-200 dark:border-gray-700 rounded-lg shadow-lg p-2 grid grid-cols-2 gap-1 w-64">
+              {DOCUMENT_CATEGORIES.map((cat) => (
+                <button
+                  key={cat.value}
+                  onClick={() => {
+                    updateCategory(sessionId, cat.value)
+                    setEditingActiveCategory(false)
+                  }}
+                  className={`text-xs px-2 py-1.5 rounded-md text-left transition-colors ${
+                    activeCategory === cat.value
+                      ? 'bg-teal-100 dark:bg-teal-900/40 text-teal-700 dark:text-teal-300'
+                      : 'hover:bg-gray-100 dark:hover:bg-gray-700 text-gray-600 dark:text-gray-400'
+                  }`}
+                >
+                  {cat.icon} {cat.label}
+                </button>
+              ))}
+            </div>
+          )}
         </div>
       )}
 
@@ -543,6 +610,26 @@ export default function OcrOverlayPage() {
       />
 
       <div className="min-h-[400px]">{renderStep()}</div>
+
+      {/* Ground Truth button bar — visible on last step */}
+      {showGtButton && (
+        <div className="sticky bottom-0 bg-white dark:bg-gray-900 border-t dark:border-gray-700 py-3 px-4 -mx-1 flex items-center justify-between rounded-b-xl">
+          <div className="text-sm text-gray-500 dark:text-gray-400">
+            {gtMessage && (
+              <span className={gtMessage.includes('fehlgeschlagen') ? 'text-red-500' : 'text-amber-600 dark:text-amber-400'}>
+                {gtMessage}
+              </span>
+            )}
+          </div>
+          <button
+            onClick={handleMarkGroundTruth}
+            disabled={gtSaving}
+            className="px-4 py-2 text-sm bg-amber-600 text-white rounded hover:bg-amber-700 disabled:opacity-50"
+          >
+            {gtSaving ? 'Speichere...' : isGroundTruth ? 'Ground Truth aktualisieren' : 'Als Ground Truth markieren'}
+          </button>
+        </div>
+      )}
     </div>
   )
 }

admin-lehrer/components/ocr-pipeline/StepGroundTruth.tsx

@@ -210,7 +210,7 @@ export function StepGroundTruth({ sessionId, onNext }: StepGroundTruthProps) {
     setGtMessage('')
     try {
       const resp = await fetch(
-        `${KLAUSUR_API}/api/v1/ocr-pipeline/sessions/${sessionId}/mark-ground-truth`,
+        `${KLAUSUR_API}/api/v1/ocr-pipeline/sessions/${sessionId}/mark-ground-truth?pipeline=ocr-pipeline`,
         { method: 'POST' }
       )
       if (!resp.ok) {