Add "OCR neu + Grid" button to Grid Review

New endpoint POST /sessions/{id}/rerun-ocr-and-build-grid that:
1. Runs scan quality assessment
2. Applies CLAHE enhancement if degraded (controlled by enhance toggle)
3. Re-runs dual-engine OCR (RapidOCR + Tesseract) with min_conf filter
4. Merges OCR results and stores updated word_result
5. Builds grid with max_columns constraint

Frontend: Orange "OCR neu + Grid" button in GridToolbar.
Unlike "Neu berechnen" (which only rebuilds grid from existing words),
this button re-runs the full OCR pipeline with quality settings.

Now CLAHE toggle actually has an effect — it enhances the image
before OCR runs, not after.

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

admin-lehrer/components/grid-editor/useGridEditor.ts

@@ -80,6 +80,38 @@ export function useGridEditor(sessionId: string | null) {
     }
   }, [sessionId, ipaMode, syllableMode, ocrEnhance, ocrMaxCols, ocrMinConf])
 
+  /** Re-run OCR with current quality settings, then rebuild grid */
+  const rerunOcr = useCallback(async () => {
+    if (!sessionId) return
+    setLoading(true)
+    setError(null)
+    try {
+      const params = new URLSearchParams()
+      params.set('ipa_mode', ipaMode)
+      params.set('syllable_mode', syllableMode)
+      params.set('enhance', String(ocrEnhance))
+      if (ocrMaxCols > 0) params.set('max_cols', String(ocrMaxCols))
+      if (ocrMinConf > 0) params.set('min_conf', String(ocrMinConf))
+      const res = await fetch(
+        `${KLAUSUR_API}/api/v1/ocr-pipeline/sessions/${sessionId}/rerun-ocr-and-build-grid?${params}`,
+        { method: 'POST' },
+      )
+      if (!res.ok) {
+        const data = await res.json().catch(() => ({}))
+        throw new Error(data.detail || `HTTP ${res.status}`)
+      }
+      const data: StructuredGrid = await res.json()
+      setGrid(data)
+      setDirty(false)
+      undoStack.current = []
+      redoStack.current = []
+    } catch (e) {
+      setError(e instanceof Error ? e.message : String(e))
+    } finally {
+      setLoading(false)
+    }
+  }, [sessionId, ipaMode, syllableMode, ocrEnhance, ocrMaxCols, ocrMinConf])
+
   const loadGrid = useCallback(async () => {
     if (!sessionId) return
     setLoading(true)
@@ -998,5 +1030,6 @@ export function useGridEditor(sessionId: string | null) {
     setOcrMaxCols,
     ocrMinConf,
     setOcrMinConf,
+    rerunOcr,
   }
 }

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

@@ -67,6 +67,7 @@ export function StepGridReview({ sessionId, onNext, saveRef }: StepGridReviewPro
     setOcrMaxCols,
     ocrMinConf,
     setOcrMinConf,
+    rerunOcr,
   } = useGridEditor(sessionId)
 
   const [showImage, setShowImage] = useState(true)
@@ -336,6 +337,14 @@ export function StepGridReview({ sessionId, onNext, saveRef }: StepGridReviewPro
           onIpaModeChange={setIpaMode}
           onSyllableModeChange={setSyllableMode}
         />
+        <button
+          onClick={rerunOcr}
+          disabled={loading}
+          className="ml-2 px-3 py-1.5 text-xs font-medium rounded border border-orange-300 dark:border-orange-700 bg-orange-50 dark:bg-orange-900/20 text-orange-700 dark:text-orange-300 hover:bg-orange-100 dark:hover:bg-orange-900/40 transition-colors disabled:opacity-50"
+          title="OCR komplett neu ausfuehren mit aktuellen Quality-Step-Einstellungen (CLAHE, MinConf), dann Grid neu bauen"
+        >
+          {loading ? 'OCR laeuft...' : 'OCR neu + Grid'}
+        </button>
       </div>
 
       {/* Split View: Image left + Grid right */}