Fix word-gap merge: add missing pronouns to stop words, reduce threshold

- Add du/dich/dir/mich/mir/uns/euch/ihm/ihn to _STOP_WORDS to prevent
  false merges like "du" + "zerlegst" → "duzerlegst"
- Reduce max_short threshold from 6 to 5 to prevent merging multi-word
  phrases like "ziehen lassen" → "ziehenlassen"

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

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

@@ -40,9 +40,9 @@ function OcrKombiContent() {
     deleteSession,
     renameSession,
     updateCategory,
-    handleOrientationComplete,
     handleSessionChange,
     setSessionId,
+    setSessionName,
     setSubSessions,
     setParentSessionId,
     setIsGroundTruth,
@@ -53,19 +53,20 @@ function OcrKombiContent() {
       case 0:
         return (
           <StepUpload
-            onUploaded={(sid) => {
+            sessionId={sessionId}
+            onUploaded={(sid, name) => {
               setSessionId(sid)
+              setSessionName(name)
               loadSessions()
-              openSession(sid)
-              handleNext()
             }}
+            onNext={handleNext}
           />
         )
       case 1:
         return (
           <StepOrientation
             sessionId={sessionId}
-            onNext={handleOrientationComplete}
+            onNext={() => handleNext()}
             onSessionList={() => { loadSessions(); handleNewSession() }}
           />
         )
@@ -73,10 +74,19 @@ function OcrKombiContent() {
         return (
           <StepPageSplit
             sessionId={sessionId}
-            onNext={handleNext}
+            sessionName={sessionName}
+            onNext={() => {
+              // If sub-sessions were created, switch to the first one
+              if (subSessions.length > 0) {
+                setSessionId(subSessions[0].id)
+                setSessionName(subSessions[0].name)
+              }
+              handleNext()
+            }}
             onSubSessionsCreated={(subs) => {
               setSubSessions(subs)
               if (sessionId) setParentSessionId(sessionId)
+              loadSessions()
             }}
           />
         )

admin-lehrer/app/(admin)/ai/ocr-kombi/useKombiPipeline.ts

@@ -154,8 +154,8 @@ export function useKombiPipeline() {
         uiStep = dbStepToKombiV2Ui(dbStep)
       }
 
-      // For sessions that already have an upload, skip the upload step
-      if (uiStep === 0 && dbStep >= 2) {
+      // Sessions only exist after upload, so always skip the upload step
+      if (uiStep === 0) {
         uiStep = 1
       }
 
@@ -356,6 +356,7 @@ export function useKombiPipeline() {
     setSessionId,
     setSubSessions,
     setParentSessionId,
+    setSessionName,
     setIsGroundTruth,
   }
 }

admin-lehrer/components/ocr-kombi/StepOrientation.tsx

@@ -4,17 +4,17 @@ import { StepOrientation as BaseStepOrientation } from '@/components/ocr-pipelin
 
 interface StepOrientationProps {
   sessionId: string | null
-  onNext: (sessionId: string) => void
+  onNext: () => void
   onSessionList: () => void
 }
 
-/** Thin wrapper around the shared StepOrientation component */
+/** Thin wrapper — adapts the shared StepOrientation to the Kombi pipeline's simpler onNext() */
 export function StepOrientation({ sessionId, onNext, onSessionList }: StepOrientationProps) {
   return (
     <BaseStepOrientation
       key={sessionId}
       sessionId={sessionId}
-      onNext={onNext}
+      onNext={() => onNext()}
       onSessionList={onSessionList}
     />
   )

admin-lehrer/components/ocr-kombi/StepPageSplit.tsx

@@ -1,123 +1,201 @@
 'use client'
 
-import { useState, useEffect } from 'react'
+import { useState, useEffect, useRef } from 'react'
 import type { SubSession } from '@/app/(admin)/ai/ocr-pipeline/types'
 
 const KLAUSUR_API = '/klausur-api'
 
+interface PageSplitResult {
+  multi_page: boolean
+  page_count?: number
+  page_splits?: { x: number; y: number; width: number; height: number; page_index: number }[]
+  sub_sessions?: { id: string; name: string; page_index: number }[]
+  used_original?: boolean
+  duration_seconds?: number
+}
+
 interface StepPageSplitProps {
   sessionId: string | null
+  sessionName: string
   onNext: () => void
   onSubSessionsCreated: (subs: SubSession[]) => void
 }
 
-/**
- * Step 3: Page split detection.
- * Checks if the image is a double-page spread and offers to split it.
- * If no split needed, auto-advances.
- */
-export function StepPageSplit({ sessionId, onNext, onSubSessionsCreated }: StepPageSplitProps) {
-  const [checking, setChecking] = useState(false)
-  const [splitResult, setSplitResult] = useState<{ is_double_page: boolean; pages?: number } | null>(null)
-  const [splitting, setSplitting] = useState(false)
+export function StepPageSplit({ sessionId, sessionName, onNext, onSubSessionsCreated }: StepPageSplitProps) {
+  const [detecting, setDetecting] = useState(false)
+  const [splitResult, setSplitResult] = useState<PageSplitResult | null>(null)
   const [error, setError] = useState('')
+  const didDetect = useRef(false)
 
+  // Auto-detect page split when step opens
   useEffect(() => {
-    if (!sessionId) return
-    // Auto-check for page split
-    checkPageSplit()
+    if (!sessionId || didDetect.current) return
+    didDetect.current = true
+    detectPageSplit()
   // eslint-disable-next-line react-hooks/exhaustive-deps
   }, [sessionId])
 
-  const checkPageSplit = async () => {
+  const detectPageSplit = async () => {
     if (!sessionId) return
-    setChecking(true)
+    setDetecting(true)
     setError('')
     try {
-      const res = await fetch(`${KLAUSUR_API}/api/v1/ocr-pipeline/sessions/${sessionId}`)
-      if (!res.ok) throw new Error('Session nicht gefunden')
-      const data = await res.json()
-
-      // If sub-sessions already exist, this was already split
-      if (data.sub_sessions?.length > 0) {
-        onSubSessionsCreated(data.sub_sessions)
-        onNext()
+      // First check if sub-sessions already exist
+      const sessionRes = await fetch(`${KLAUSUR_API}/api/v1/ocr-pipeline/sessions/${sessionId}`)
+      if (sessionRes.ok) {
+        const sessionData = await sessionRes.json()
+        if (sessionData.sub_sessions?.length > 0) {
+          // Already split — show existing sub-sessions
+          const subs = sessionData.sub_sessions as { id: string; name: string; page_index?: number; box_index?: number; current_step?: number }[]
+          setSplitResult({
+            multi_page: true,
+            page_count: subs.length,
+            sub_sessions: subs.map((s: { id: string; name: string; page_index?: number; box_index?: number }) => ({
+              id: s.id,
+              name: s.name,
+              page_index: s.page_index ?? s.box_index ?? 0,
+            })),
+          })
+          onSubSessionsCreated(subs.map((s: { id: string; name: string; page_index?: number; box_index?: number; current_step?: number }) => ({
+            id: s.id,
+            name: s.name,
+            box_index: s.page_index ?? s.box_index ?? 0,
+            current_step: s.current_step ?? 2,
+          })))
+          setDetecting(false)
           return
         }
-
-      // Check aspect ratio to guess if double-page
-      // For now, just auto-advance (page-split detection happens in orientation step)
-      setSplitResult({ is_double_page: false })
-      // Auto-advance if single page
-      onNext()
-    } catch (e) {
-      setError(e instanceof Error ? e.message : String(e))
-    } finally {
-      setChecking(false)
-    }
       }
 
-  const handleSplit = async () => {
-    if (!sessionId) return
-    setSplitting(true)
-    setError('')
-    try {
+      // Run page-split detection
       const res = await fetch(`${KLAUSUR_API}/api/v1/ocr-pipeline/sessions/${sessionId}/page-split`, {
         method: 'POST',
       })
       if (!res.ok) {
         const data = await res.json().catch(() => ({}))
-        throw new Error(data.detail || 'Split fehlgeschlagen')
+        throw new Error(data.detail || 'Seitentrennung fehlgeschlagen')
       }
-      const data = await res.json()
-      if (data.sub_sessions?.length > 0) {
-        onSubSessionsCreated(data.sub_sessions)
+      const data: PageSplitResult = await res.json()
+      setSplitResult(data)
+
+      if (data.multi_page && data.sub_sessions?.length) {
+        // Rename sub-sessions to "Title — S. 1", "Title — S. 2"
+        const baseName = sessionName || 'Dokument'
+        for (let i = 0; i < data.sub_sessions.length; i++) {
+          const sub = data.sub_sessions[i]
+          const newName = `${baseName} — S. ${i + 1}`
+          await fetch(`${KLAUSUR_API}/api/v1/ocr-pipeline/sessions/${sub.id}`, {
+            method: 'PUT',
+            headers: { 'Content-Type': 'application/json' },
+            body: JSON.stringify({ name: newName }),
+          }).catch(() => {})
+          sub.name = newName
+        }
+
+        onSubSessionsCreated(data.sub_sessions.map(s => ({
+          id: s.id,
+          name: s.name,
+          box_index: s.page_index,
+          current_step: 2,
+        })))
       }
-      onNext()
     } catch (e) {
       setError(e instanceof Error ? e.message : String(e))
     } finally {
-      setSplitting(false)
+      setDetecting(false)
     }
   }
 
-  if (checking) {
-    return <div className="text-sm text-gray-500 py-8 text-center">Pruefe Seitenformat...</div>
-  }
+  if (!sessionId) return null
+
+  const imageUrl = `${KLAUSUR_API}/api/v1/ocr-pipeline/sessions/${sessionId}/image/oriented`
 
-  if (splitResult?.is_double_page) {
   return (
-      <div className="space-y-4 p-6 bg-blue-50 dark:bg-blue-900/20 rounded-xl border border-blue-200 dark:border-blue-800">
-        <h3 className="text-sm font-medium text-blue-700 dark:text-blue-300">
-          Doppelseite erkannt
-        </h3>
-        <p className="text-sm text-blue-600 dark:text-blue-400">
-          Das Bild scheint eine Doppelseite zu sein. Soll es in zwei Einzelseiten aufgeteilt werden?
+    <div className="space-y-4">
+      {/* Image */}
+      <div className="relative rounded-lg overflow-hidden bg-gray-100 dark:bg-gray-700">
+        {/* eslint-disable-next-line @next/next/no-img-element */}
+        <img
+          src={imageUrl}
+          alt="Orientiertes Bild"
+          className="w-full object-contain max-h-[500px]"
+          onError={(e) => {
+            // Fallback to non-oriented image
+            (e.target as HTMLImageElement).src =
+              `${KLAUSUR_API}/api/v1/ocr-pipeline/sessions/${sessionId}/image`
+          }}
+        />
+      </div>
+
+      {/* Detection status */}
+      {detecting && (
+        <div className="flex items-center gap-2 text-teal-600 dark:text-teal-400 text-sm">
+          <div className="animate-spin w-4 h-4 border-2 border-teal-500 border-t-transparent rounded-full" />
+          Doppelseiten-Erkennung laeuft...
+        </div>
+      )}
+
+      {/* Detection result */}
+      {splitResult && !detecting && (
+        splitResult.multi_page ? (
+          <div className="bg-blue-50 dark:bg-blue-900/20 rounded-lg border border-blue-200 dark:border-blue-700 p-4 space-y-2">
+            <div className="text-sm font-medium text-blue-700 dark:text-blue-300">
+              Doppelseite erkannt — {splitResult.page_count} Seiten getrennt
+            </div>
+            <p className="text-xs text-blue-600 dark:text-blue-400">
+              Jede Seite wird als eigene Session weiterverarbeitet (eigene Begradigung, Entzerrung, etc.).
+              {splitResult.used_original && ' Trennung auf Originalbild, da Orientierung die Doppelseite gedreht hat.'}
             </p>
-        <div className="flex gap-2">
-          <button
-            onClick={handleSplit}
-            disabled={splitting}
-            className="px-4 py-2 bg-blue-600 text-white text-sm rounded-lg hover:bg-blue-700 disabled:opacity-50"
+            <div className="flex gap-2 mt-2">
+              {splitResult.sub_sessions?.map(s => (
+                <span
+                  key={s.id}
+                  className="text-xs px-2.5 py-1 rounded-md bg-blue-100 dark:bg-blue-800/40 text-blue-700 dark:text-blue-300 font-medium"
                 >
-            {splitting ? 'Wird aufgeteilt...' : 'Aufteilen'}
+                  {s.name}
+                </span>
+              ))}
+            </div>
+            {splitResult.duration_seconds != null && (
+              <div className="text-xs text-gray-400">{splitResult.duration_seconds.toFixed(1)}s</div>
+            )}
+          </div>
+        ) : (
+          <div className="bg-green-50 dark:bg-green-900/20 rounded-lg border border-green-200 dark:border-green-800 p-4">
+            <div className="flex items-center gap-2 text-sm font-medium text-green-700 dark:text-green-300">
+              <span>&#10003;</span> Einzelseite — keine Trennung noetig
+            </div>
+            {splitResult.duration_seconds != null && (
+              <div className="text-xs text-gray-400 mt-1">{splitResult.duration_seconds.toFixed(1)}s</div>
+            )}
+          </div>
+        )
+      )}
+
+      {/* Error */}
+      {error && (
+        <div className="text-sm text-red-500 bg-red-50 dark:bg-red-900/20 p-3 rounded-lg">
+          {error}
+          <button
+            onClick={() => { didDetect.current = false; detectPageSplit() }}
+            className="ml-2 text-teal-600 hover:underline"
+          >
+            Erneut versuchen
           </button>
+        </div>
+      )}
+
+      {/* Next button — only show when detection is done */}
+      {(splitResult || error) && !detecting && (
+        <div className="flex justify-end">
           <button
             onClick={onNext}
-            className="px-4 py-2 bg-gray-200 dark:bg-gray-700 text-sm rounded-lg hover:bg-gray-300"
+            className="px-6 py-2.5 bg-teal-600 text-white text-sm font-medium rounded-lg hover:bg-teal-700 transition-colors"
           >
-            Einzelseite beibehalten
+            Weiter &rarr;
           </button>
         </div>
-        {error && <div className="text-sm text-red-500">{error}</div>}
-      </div>
-    )
-  }
-
-  return (
-    <div className="text-sm text-gray-500 py-8 text-center">
-      Einzelseite erkannt — weiter zum naechsten Schritt.
-      {error && <div className="text-sm text-red-500 mt-2">{error}</div>}
+      )}
     </div>
   )
 }

admin-lehrer/components/ocr-kombi/StepUpload.tsx

@@ -1,28 +1,52 @@
 'use client'
 
-import { useState, useCallback } from 'react'
+import { useState, useCallback, useEffect } from 'react'
 import { DOCUMENT_CATEGORIES, type DocumentCategory } from '@/app/(admin)/ai/ocr-pipeline/types'
 
 const KLAUSUR_API = '/klausur-api'
 
 interface StepUploadProps {
-  onUploaded: (sessionId: string) => void
+  sessionId: string | null
+  onUploaded: (sessionId: string, name: string) => void
+  onNext: () => void
 }
 
-export function StepUpload({ onUploaded }: StepUploadProps) {
+export function StepUpload({ sessionId, onUploaded, onNext }: StepUploadProps) {
   const [dragging, setDragging] = useState(false)
   const [uploading, setUploading] = useState(false)
+  const [selectedFile, setSelectedFile] = useState<File | null>(null)
+  const [preview, setPreview] = useState<string | null>(null)
   const [title, setTitle] = useState('')
   const [category, setCategory] = useState<DocumentCategory>('vokabelseite')
   const [error, setError] = useState('')
 
-  const handleUpload = useCallback(async (file: File) => {
+  // Clean up preview URL on unmount
+  useEffect(() => {
+    return () => { if (preview) URL.revokeObjectURL(preview) }
+  }, [preview])
+
+  const handleFileSelect = useCallback((file: File) => {
+    setSelectedFile(file)
+    setError('')
+    if (file.type.startsWith('image/')) {
+      setPreview(URL.createObjectURL(file))
+    } else {
+      setPreview(null)
+    }
+    // Auto-fill title from filename if empty
+    if (!title.trim()) {
+      setTitle(file.name.replace(/\.[^.]+$/, ''))
+    }
+  }, [title])
+
+  const handleUpload = useCallback(async () => {
+    if (!selectedFile) return
     setUploading(true)
     setError('')
 
     try {
       const formData = new FormData()
-      formData.append('file', file)
+      formData.append('file', selectedFile)
       if (title.trim()) formData.append('name', title.trim())
 
       const res = await fetch(`${KLAUSUR_API}/api/v1/ocr-pipeline/sessions`, {
@@ -47,26 +71,164 @@ export function StepUpload({ onUploaded }: StepUploadProps) {
         })
       }
 
-      onUploaded(sid)
+      onUploaded(sid, title.trim() || selectedFile.name)
     } catch (e) {
       setError(e instanceof Error ? e.message : String(e))
     } finally {
       setUploading(false)
     }
-  }, [title, category, onUploaded])
+  }, [selectedFile, title, category, onUploaded])
 
   const handleDrop = useCallback((e: React.DragEvent) => {
     e.preventDefault()
     setDragging(false)
     const file = e.dataTransfer.files[0]
-    if (file) handleUpload(file)
-  }, [handleUpload])
+    if (file) handleFileSelect(file)
+  }, [handleFileSelect])
 
-  const handleFileSelect = useCallback((e: React.ChangeEvent<HTMLInputElement>) => {
+  const handleInputChange = useCallback((e: React.ChangeEvent<HTMLInputElement>) => {
     const file = e.target.files?.[0]
-    if (file) handleUpload(file)
-  }, [handleUpload])
+    if (file) handleFileSelect(file)
+  }, [handleFileSelect])
 
+  const clearFile = useCallback(() => {
+    setSelectedFile(null)
+    if (preview) URL.revokeObjectURL(preview)
+    setPreview(null)
+  }, [preview])
+
+  // ---- Phase 2: Uploaded → show result + "Weiter" ----
+  if (sessionId) {
+    return (
+      <div className="space-y-4">
+        <div className="bg-green-50 dark:bg-green-900/20 border border-green-200 dark:border-green-800 rounded-lg p-4">
+          <div className="flex items-center gap-2 text-green-700 dark:text-green-300 text-sm font-medium mb-3">
+            <span>&#10003;</span> Dokument hochgeladen
+          </div>
+          <div className="flex gap-4">
+            <div className="w-48 h-64 rounded-lg overflow-hidden bg-gray-100 dark:bg-gray-700 flex-shrink-0 border border-gray-200 dark:border-gray-600">
+              {/* eslint-disable-next-line @next/next/no-img-element */}
+              <img
+                src={`${KLAUSUR_API}/api/v1/ocr-pipeline/sessions/${sessionId}/image`}
+                alt="Hochgeladenes Dokument"
+                className="w-full h-full object-contain"
+                onError={(e) => { (e.target as HTMLImageElement).style.display = 'none' }}
+              />
+            </div>
+            <div className="text-sm text-gray-600 dark:text-gray-400">
+              <div className="font-medium text-gray-700 dark:text-gray-300 mb-1">
+                {title || 'Dokument'}
+              </div>
+              <div className="text-xs text-gray-400 mt-1">
+                Kategorie: {DOCUMENT_CATEGORIES.find(c => c.value === category)?.label || category}
+              </div>
+              <div className="text-xs font-mono text-gray-400 mt-1">
+                Session: {sessionId.slice(0, 8)}...
+              </div>
+            </div>
+          </div>
+        </div>
+
+        <div className="flex justify-end">
+          <button
+            onClick={onNext}
+            className="px-6 py-2.5 bg-teal-600 text-white text-sm font-medium rounded-lg hover:bg-teal-700 transition-colors"
+          >
+            Weiter &rarr;
+          </button>
+        </div>
+      </div>
+    )
+  }
+
+  // ---- Phase 1b: File selected → preview + "Hochladen" ----
+  if (selectedFile) {
+    return (
+      <div className="space-y-4">
+        {/* Title input */}
+        <div>
+          <label className="block text-sm font-medium text-gray-700 dark:text-gray-300 mb-1">
+            Titel
+          </label>
+          <input
+            type="text"
+            value={title}
+            onChange={(e) => setTitle(e.target.value)}
+            placeholder="z.B. Vokabeln Unit 3"
+            className="w-full px-3 py-2 border border-gray-300 dark:border-gray-600 rounded-lg bg-white dark:bg-gray-800 text-sm"
+          />
+        </div>
+
+        {/* Category selector */}
+        <div>
+          <label className="block text-sm font-medium text-gray-700 dark:text-gray-300 mb-1">
+            Kategorie
+          </label>
+          <div className="grid grid-cols-4 gap-1.5">
+            {DOCUMENT_CATEGORIES.map(cat => (
+              <button
+                key={cat.value}
+                onClick={() => setCategory(cat.value)}
+                className={`text-xs px-2 py-1.5 rounded-md text-left transition-colors ${
+                  category === cat.value
+                    ? 'bg-teal-100 dark:bg-teal-900/40 text-teal-700 dark:text-teal-300 ring-1 ring-teal-400'
+                    : 'bg-gray-50 dark:bg-gray-700 text-gray-600 dark:text-gray-400 hover:bg-gray-100'
+                }`}
+              >
+                {cat.icon} {cat.label}
+              </button>
+            ))}
+          </div>
+        </div>
+
+        {/* File preview */}
+        <div className="border border-gray-200 dark:border-gray-700 rounded-xl p-4">
+          <div className="flex items-start gap-4">
+            {preview ? (
+              <div className="w-36 h-48 rounded-lg overflow-hidden bg-gray-100 dark:bg-gray-700 flex-shrink-0 border border-gray-200 dark:border-gray-600">
+                {/* eslint-disable-next-line @next/next/no-img-element */}
+                <img src={preview} alt="Vorschau" className="w-full h-full object-contain" />
+              </div>
+            ) : (
+              <div className="w-36 h-48 rounded-lg bg-gray-100 dark:bg-gray-700 flex-shrink-0 flex items-center justify-center border border-gray-200 dark:border-gray-600">
+                <span className="text-3xl">&#128196;</span>
+              </div>
+            )}
+            <div className="flex-1 min-w-0">
+              <div className="font-medium text-sm text-gray-700 dark:text-gray-300 truncate">
+                {selectedFile.name}
+              </div>
+              <div className="text-xs text-gray-400 mt-1">
+                {(selectedFile.size / 1024 / 1024).toFixed(1)} MB
+              </div>
+              <button
+                onClick={clearFile}
+                className="text-xs text-red-500 hover:text-red-700 mt-2"
+              >
+                Andere Datei waehlen
+              </button>
+            </div>
+          </div>
+
+          <button
+            onClick={handleUpload}
+            disabled={uploading}
+            className="mt-4 w-full px-4 py-2.5 bg-teal-600 text-white text-sm font-medium rounded-lg hover:bg-teal-700 disabled:opacity-50 disabled:cursor-not-allowed transition-colors"
+          >
+            {uploading ? 'Wird hochgeladen...' : 'Hochladen'}
+          </button>
+        </div>
+
+        {error && (
+          <div className="text-sm text-red-500 bg-red-50 dark:bg-red-900/20 p-3 rounded-lg">
+            {error}
+          </div>
+        )}
+      </div>
+    )
+  }
+
+  // ---- Phase 1a: No file → drop zone ----
   return (
     <div className="space-y-4">
       {/* Title input */}
@@ -116,11 +278,7 @@ export function StepUpload({ onUploaded }: StepUploadProps) {
             : 'border-gray-300 dark:border-gray-600 hover:border-gray-400'
         }`}
       >
-        {uploading ? (
-          <div className="text-sm text-gray-500">Wird hochgeladen...</div>
-        ) : (
-          <>
-            <div className="text-4xl mb-3">📤</div>
+        <div className="text-4xl mb-3">&#128228;</div>
         <div className="text-sm text-gray-600 dark:text-gray-400 mb-2">
           Bild oder PDF hierher ziehen
         </div>
@@ -129,12 +287,10 @@ export function StepUpload({ onUploaded }: StepUploadProps) {
           <input
             type="file"
             accept="image/*,.pdf"
-                onChange={handleFileSelect}
+            onChange={handleInputChange}
             className="hidden"
           />
         </label>
-          </>
-        )}
       </div>
 
       {error && (

klausur-service/backend/cv_syllable_detect.py

@@ -34,7 +34,8 @@ _STOP_WORDS = frozenset([
     'der', 'die', 'das', 'dem', 'den', 'des',
     'ein', 'eine', 'einem', 'einen', 'einer',
     # Pronouns
-    'er', 'es', 'sie', 'wir', 'ihr', 'ich', 'man', 'sich',
+    'du', 'er', 'es', 'sie', 'wir', 'ihr', 'ich', 'man', 'sich',
+    'dich', 'dir', 'mich', 'mir', 'uns', 'euch', 'ihm', 'ihn',
     # Prepositions
     'mit', 'von', 'zu', 'für', 'auf', 'in', 'an', 'um', 'am', 'im',
     'aus', 'bei', 'nach', 'vor', 'bis', 'durch', 'über', 'unter',
@@ -139,6 +140,93 @@ def _try_merge_pipe_gaps(text: str, hyph_de) -> str:
     return ' '.join(result)
 
 
+def merge_word_gaps_in_zones(zones_data: List[Dict], session_id: str) -> int:
+    """Merge OCR word-gap fragments in cell texts using pyphen validation.
+
+    OCR often splits words at syllable boundaries into separate word_boxes,
+    producing text like "zerknit tert" instead of "zerknittert".  This
+    function tries to merge adjacent fragments in every content cell.
+
+    More permissive than ``_try_merge_pipe_gaps`` (threshold 5 instead of 3)
+    but still guarded by pyphen dictionary lookup and stop-word exclusion.
+
+    Returns the number of cells modified.
+    """
+    hyph_de, _ = _get_hyphenators()
+    if hyph_de is None:
+        return 0
+
+    modified = 0
+    for z in zones_data:
+        for cell in z.get("cells", []):
+            ct = cell.get("col_type", "")
+            if not ct.startswith("column_"):
+                continue
+            text = cell.get("text", "")
+            if not text or " " not in text:
+                continue
+
+            # Skip IPA cells
+            text_no_brackets = re.sub(r'\[[^\]]*\]', '', text)
+            if _IPA_RE.search(text_no_brackets):
+                continue
+
+            new_text = _try_merge_word_gaps(text, hyph_de)
+            if new_text != text:
+                cell["text"] = new_text
+                modified += 1
+
+    if modified:
+        logger.info(
+            "build-grid session %s: merged word gaps in %d cells",
+            session_id, modified,
+        )
+    return modified
+
+
+def _try_merge_word_gaps(text: str, hyph_de) -> str:
+    """Merge OCR word fragments with relaxed threshold (max_short=6).
+
+    Similar to ``_try_merge_pipe_gaps`` but allows slightly longer fragments
+    (max_short=5 instead of 3).  Still requires pyphen to recognize the
+    merged word.
+    """
+    parts = text.split(' ')
+    if len(parts) < 2:
+        return text
+
+    result = [parts[0]]
+    i = 1
+    while i < len(parts):
+        prev = result[-1]
+        curr = parts[i]
+
+        prev_alpha = re.sub(r'[^a-zA-ZäöüÄÖÜßẞ]', '', prev)
+        curr_alpha = re.sub(r'[^a-zA-ZäöüÄÖÜßẞ]', '', curr)
+
+        should_try = (
+            prev == prev_alpha
+            and prev_alpha and curr_alpha
+            and prev_alpha.lower() not in _STOP_WORDS
+            and curr_alpha.lower() not in _STOP_WORDS
+            and min(len(prev_alpha), len(curr_alpha)) <= 5
+            and len(prev_alpha) + len(curr_alpha) >= 4
+        )
+
+        if should_try:
+            merged_alpha = prev_alpha + curr_alpha
+            hyph = hyph_de.inserted(merged_alpha, hyphen='-')
+            if '-' in hyph:
+                result[-1] = prev + curr
+                i += 1
+                continue
+
+        result.append(curr)
+        i += 1
+
+    return ' '.join(result)
+
+
 def _syllabify_text(text: str, hyph_de, hyph_en) -> str:
     """Syllabify all significant words in a text string.
 
@@ -259,6 +347,12 @@ def insert_syllable_dividers(
             if not text:
                 continue
 
+            # In auto mode (force=False), only normalize cells that already
+            # have | from OCR (i.e. printed syllable dividers on the original
+            # scan).  Don't add new syllable marks to other words.
+            if not force and "|" not in text:
+                continue
+
             new_text = _syllabify_text(text, hyph_de, hyph_en)
             if new_text != text:
                 cell["text"] = new_text

klausur-service/backend/grid_editor_api.py

@@ -1593,6 +1593,13 @@ async def _build_grid_core(
     except Exception as e:
         logger.warning("Dictionary detection failed: %s", e)
 
+    # --- Word-gap merge: fix OCR splits like "zerknit tert" → "zerknittert" ---
+    try:
+        from cv_syllable_detect import merge_word_gaps_in_zones
+        merge_word_gaps_in_zones(zones_data, session_id)
+    except Exception as e:
+        logger.warning("Word-gap merge failed: %s", e)
+
     # --- Syllable divider insertion for dictionary pages ---
     # syllable_mode: "auto" = only when original has pipe dividers (1% threshold),
     #   "all" = force on all content words, "en" = English column only,
@@ -1626,6 +1633,15 @@ async def _build_grid_core(
             except Exception as e:
                 logger.warning("Syllable insertion failed: %s", e)
 
+    # When syllable mode is "none", strip any residual | from OCR so
+    # that the displayed text is clean (e.g. "Zel|le" → "Zelle").
+    if syllable_mode == "none":
+        for z in zones_data:
+            for cell in z.get("cells", []):
+                t = cell.get("text", "")
+                if "|" in t:
+                    cell["text"] = t.replace("|", "")
+
     # Clean up internal flags before returning
     for z in zones_data:
         for cell in z.get("cells", []):

klausur-service/backend/grid_editor_helpers.py

@@ -912,6 +912,13 @@ def _detect_heading_rows_by_single_cell(
             _REAL_IPA_CHARS = set("ˈˌəɪɛɒʊʌæɑɔʃʒθðŋ")
             if _text_has_garbled_ipa(text) and not any(c in _REAL_IPA_CHARS for c in text):
                 continue
+            # Guard: dictionary section headings are short (1-4 alpha chars
+            # like "A", "Ab", "Zi", "Sch").  Longer text that starts
+            # lowercase is a regular vocabulary word (e.g. "zentral") that
+            # happens to appear alone in its row.
+            alpha_only = re.sub(r'[^a-zA-ZäöüÄÖÜßẞ]', '', text)
+            if len(alpha_only) > 4 and text[0].islower():
+                continue
             heading_row_indices.append(ri)
 
         # Guard: if >25% of eligible rows would become headings, the