diff --git a/services/xai_service.py b/services/xai_service.py
index 49d56e9..b66e94f 100644
--- a/services/xai_service.py
+++ b/services/xai_service.py
@@ -112,12 +112,9 @@ class XAIService:
 
     async def add_to_collection(self, collection_id: str, file_id: str) -> None:
         """
-        Fügt eine Datei einer xAI-Collection (Vector Store) hinzu.
+        Fügt eine Datei einer xAI-Collection hinzu.
 
-        POST https://api.x.ai/v1/vector_stores/{vector_store_id}/files
-
-        Uses the OpenAI-compatible API pattern for adding files to vector stores.
-        This triggers proper indexing and processing.
+        POST https://management-api.x.ai/v1/collections/{collection_id}/documents/{file_id}
 
         Raises:
             RuntimeError: bei HTTP-Fehler
@@ -125,16 +122,10 @@ class XAIService:
         self._log(f"📚 Adding file {file_id} to collection {collection_id}")
 
         session = await self._get_session()
-        # Use the OpenAI-compatible endpoint (not management API)
-        url = f"{XAI_FILES_URL}/v1/vector_stores/{collection_id}/files"
-        headers = {
-            "Authorization": f"Bearer {self.api_key}",
-            "Content-Type": "application/json",
-        }
+        url = f"{XAI_MANAGEMENT_URL}/v1/collections/{collection_id}/documents/{file_id}"
+        headers = {"Authorization": f"Bearer {self.management_key}"}
 
-        payload = {"file_id": file_id}
-
-        async with session.post(url, json=payload, headers=headers) as response:
+        async with session.post(url, headers=headers) as response:
             if response.status not in (200, 201):
                 raw = await response.text()
                 raise RuntimeError(
diff --git a/src/steps/akte/akte_sync_event_step.py b/src/steps/akte/akte_sync_event_step.py
new file mode 100644
index 0000000..1f1bef7
--- /dev/null
+++ b/src/steps/akte/akte_sync_event_step.py
@@ -0,0 +1,435 @@
+"""
+Akte Sync - Event Handler
+
+Unified sync for one CAkten entity across all configured backends:
+  - Advoware (3-way merge: Windows ↔ EspoCRM ↔ History)
+  - xAI       (Blake3 hash-based upload to Collection)
+
+Both run in the same event to keep CDokumente perfectly in sync.
+
+Trigger:  akte.sync   { akte_id, aktennummer }
+Lock:     Redis per-Akte (30 min TTL, prevents double-sync of same Akte)
+Parallel: Different Akten sync simultaneously.
+
+Enqueues:
+  - document.generate_preview  (after CREATE / UPDATE_ESPO)
+"""
+
+from typing import Dict, Any
+from datetime import datetime
+from motia import FlowContext, queue
+
+
+config = {
+    "name": "Akte Sync - Event Handler",
+    "description": "Unified sync for one Akte: Advoware 3-way merge + xAI upload",
+    "flows": ["akte-sync"],
+    "triggers": [queue("akte.sync")],
+    "enqueues": ["document.generate_preview"],
+}
+
+
+# ─────────────────────────────────────────────────────────────────────────────
+# Entry point
+# ─────────────────────────────────────────────────────────────────────────────
+
+async def handler(event_data: Dict[str, Any], ctx: FlowContext) -> None:
+    akte_id = event_data.get('akte_id')
+    aktennummer = event_data.get('aktennummer')
+
+    ctx.logger.info("=" * 80)
+    ctx.logger.info("🔄 AKTE SYNC STARTED")
+    ctx.logger.info(f"   Aktennummer : {aktennummer}")
+    ctx.logger.info(f"   EspoCRM ID  : {akte_id}")
+    ctx.logger.info("=" * 80)
+
+    from services.redis_client import get_redis_client
+    from services.espocrm import EspoCRMAPI
+
+    redis_client = get_redis_client(strict=False)
+    if not redis_client:
+        ctx.logger.error("❌ Redis unavailable")
+        return
+
+    lock_key = f"akte_sync:{akte_id}"
+    lock_acquired = redis_client.set(lock_key, datetime.now().isoformat(), nx=True, ex=1800)
+    if not lock_acquired:
+        ctx.logger.warn(f"⏸️  Lock busy for Akte {akte_id} – requeueing")
+        raise RuntimeError(f"Lock busy for akte_id={akte_id}")
+
+    espocrm = EspoCRMAPI(ctx)
+
+    try:
+        # ── Load Akte ──────────────────────────────────────────────────────
+        akte = await espocrm.get_entity('CAkten', akte_id)
+        if not akte:
+            ctx.logger.error(f"❌ Akte {akte_id} not found in EspoCRM")
+            return
+
+        # aktennummer can come from the event payload OR from the entity
+        # (Akten without Advoware have no aktennummer)
+        if not aktennummer:
+            aktennummer = akte.get('aktennummer')
+
+        sync_schalter = akte.get('syncSchalter', False)
+        aktivierungsstatus = str(akte.get('aktivierungsstatus') or '').lower()
+        ai_aktivierungsstatus = str(akte.get('aiAktivierungsstatus') or '').lower()
+
+        ctx.logger.info(f"📋 Akte '{akte.get('name')}'")
+        ctx.logger.info(f"   syncSchalter         : {sync_schalter}")
+        ctx.logger.info(f"   aktivierungsstatus   : {aktivierungsstatus}")
+        ctx.logger.info(f"   aiAktivierungsstatus : {ai_aktivierungsstatus}")
+
+        # Advoware sync requires an aktennummer (Akten without Advoware won't have one)
+        advoware_enabled = bool(aktennummer) and sync_schalter and aktivierungsstatus in ('import', 'new', 'active')
+        xai_enabled = ai_aktivierungsstatus in ('new', 'active')
+
+        ctx.logger.info(f"   Advoware sync : {'✅ ON' if advoware_enabled else '⏭️  OFF'}")
+        ctx.logger.info(f"   xAI sync      : {'✅ ON' if xai_enabled else '⏭️  OFF'}")
+
+        if not advoware_enabled and not xai_enabled:
+            ctx.logger.info("⏭️  Both syncs disabled – nothing to do")
+            return
+
+        # ── ADVOWARE SYNC ──────────────────────────────────────────────────
+        advoware_results = None
+        if advoware_enabled:
+            advoware_results = await _run_advoware_sync(akte, aktennummer, akte_id, espocrm, ctx)
+
+        # ── xAI SYNC ──────────────────────────────────────────────────────
+        if xai_enabled:
+            await _run_xai_sync(akte, akte_id, espocrm, ctx)
+
+        # ── Final Status ───────────────────────────────────────────────────
+        now = datetime.now().strftime('%Y-%m-%d %H:%M:%S')
+        final_update: Dict[str, Any] = {'globalLastSync': now, 'globalSyncStatus': 'synced'}
+        if advoware_enabled:
+            final_update['syncStatus'] = 'synced'
+            final_update['lastSync'] = now
+            # 'import' = erster Sync → danach auf 'aktiv' setzen
+            if aktivierungsstatus == 'import':
+                final_update['aktivierungsstatus'] = 'active'
+                ctx.logger.info("🔄 aktivierungsstatus: import → active")
+        if xai_enabled:
+            final_update['aiSyncStatus'] = 'synced'
+            final_update['aiLastSync'] = now
+            # 'new' = Collection wurde gerade erstmalig angelegt → auf 'aktiv' setzen
+            if ai_aktivierungsstatus == 'new':
+                final_update['aiAktivierungsstatus'] = 'active'
+                ctx.logger.info("🔄 aiAktivierungsstatus: new → active")
+
+        await espocrm.update_entity('CAkten', akte_id, final_update)
+        # Clean up processing sets (both queues may have triggered this sync)
+        if aktennummer:
+            redis_client.srem("advoware:processing_aktennummern", aktennummer)
+        redis_client.srem("akte:processing_entity_ids", akte_id)
+
+        ctx.logger.info("=" * 80)
+        ctx.logger.info("✅ AKTE SYNC COMPLETE")
+        if advoware_results:
+            ctx.logger.info(f"   Advoware: created={advoware_results['created']} updated={advoware_results['updated']} deleted={advoware_results['deleted']} errors={advoware_results['errors']}")
+        ctx.logger.info("=" * 80)
+
+    except Exception as e:
+        ctx.logger.error(f"❌ Sync failed: {e}")
+        import traceback
+        ctx.logger.error(traceback.format_exc())
+
+        # Requeue for retry (into the appropriate queue(s))
+        import time
+        now_ts = time.time()
+        if aktennummer:
+            redis_client.zadd("advoware:pending_aktennummern", {aktennummer: now_ts})
+        redis_client.zadd("akte:pending_entity_ids", {akte_id: now_ts})
+
+        try:
+            await espocrm.update_entity('CAkten', akte_id, {
+                'syncStatus': 'failed',
+                'globalSyncStatus': 'failed',
+            })
+        except Exception:
+            pass
+        raise
+
+    finally:
+        if lock_acquired and redis_client:
+            redis_client.delete(lock_key)
+            ctx.logger.info(f"🔓 Lock released for Akte {aktennummer}")
+
+
+# ─────────────────────────────────────────────────────────────────────────────
+# Advoware 3-way merge
+# ─────────────────────────────────────────────────────────────────────────────
+
+async def _run_advoware_sync(
+    akte: Dict[str, Any],
+    aktennummer: str,
+    akte_id: str,
+    espocrm,
+    ctx: FlowContext,
+) -> Dict[str, int]:
+    from services.advoware_watcher_service import AdvowareWatcherService
+    from services.advoware_history_service import AdvowareHistoryService
+    from services.advoware_service import AdvowareService
+    from services.advoware_document_sync_utils import AdvowareDocumentSyncUtils
+    from services.blake3_utils import compute_blake3
+    import mimetypes
+
+    watcher = AdvowareWatcherService(ctx)
+    history_service = AdvowareHistoryService(ctx)
+    advoware_service = AdvowareService(ctx)
+    sync_utils = AdvowareDocumentSyncUtils(ctx)
+
+    results = {'created': 0, 'updated': 0, 'deleted': 0, 'skipped': 0, 'errors': 0}
+
+    ctx.logger.info("")
+    ctx.logger.info("─" * 60)
+    ctx.logger.info("📂 ADVOWARE SYNC")
+    ctx.logger.info("─" * 60)
+
+    # ── Fetch from all 3 sources ───────────────────────────────────────
+    espo_docs_result = await espocrm.list_related('CAkten', akte_id, 'dokumentes')
+    espo_docs = espo_docs_result.get('list', [])
+
+    try:
+        windows_files = await watcher.get_akte_files(aktennummer)
+    except Exception as e:
+        ctx.logger.error(f"❌ Windows watcher failed: {e}")
+        windows_files = []
+
+    try:
+        advo_history = await history_service.get_akte_history(aktennummer)
+    except Exception as e:
+        ctx.logger.error(f"❌ Advoware history failed: {e}")
+        advo_history = []
+
+    ctx.logger.info(f"   EspoCRM docs  : {len(espo_docs)}")
+    ctx.logger.info(f"   Windows files : {len(windows_files)}")
+    ctx.logger.info(f"   History entries: {len(advo_history)}")
+
+    # ── Cleanup Windows list (only files in History) ───────────────────
+    windows_files = sync_utils.cleanup_file_list(windows_files, advo_history)
+
+    # ── Build indexes by HNR (stable identifier from Advoware) ────────
+    espo_by_hnr = {}
+    for doc in espo_docs:
+        if doc.get('hnr'):
+            espo_by_hnr[doc['hnr']] = doc
+
+    history_by_hnr = {}
+    for entry in advo_history:
+        if entry.get('hNr'):
+            history_by_hnr[entry['hNr']] = entry
+
+    windows_by_path = {f.get('path', '').lower(): f for f in windows_files}
+
+    all_hnrs = set(espo_by_hnr.keys()) | set(history_by_hnr.keys())
+    ctx.logger.info(f"   Unique HNRs   : {len(all_hnrs)}")
+
+    # ── 3-way merge per HNR ───────────────────────────────────────────
+    for hnr in all_hnrs:
+        espo_doc = espo_by_hnr.get(hnr)
+        history_entry = history_by_hnr.get(hnr)
+
+        windows_file = None
+        if history_entry and history_entry.get('datei'):
+            windows_file = windows_by_path.get(history_entry['datei'].lower())
+
+        if history_entry and history_entry.get('datei'):
+            filename = history_entry['datei'].split('\\')[-1]
+        elif espo_doc:
+            filename = espo_doc.get('name', f'hnr_{hnr}')
+        else:
+            filename = f'hnr_{hnr}'
+
+        try:
+            action = sync_utils.merge_three_way(espo_doc, windows_file, history_entry)
+            ctx.logger.info(f"   [{action.action:12s}] {filename} (hnr={hnr}) – {action.reason}")
+
+            if action.action == 'SKIP':
+                results['skipped'] += 1
+
+            elif action.action == 'CREATE':
+                if not windows_file:
+                    ctx.logger.error(f"   ❌ CREATE: no Windows file for hnr {hnr}")
+                    results['errors'] += 1
+                    continue
+
+                content = await watcher.download_file(aktennummer, windows_file.get('relative_path', filename))
+                blake3_hash = compute_blake3(content)
+                mime_type, _ = mimetypes.guess_type(filename)
+                mime_type = mime_type or 'application/octet-stream'
+                now = datetime.now().strftime('%Y-%m-%d %H:%M:%S')
+
+                attachment = await espocrm.upload_attachment_for_file_field(
+                    file_content=content,
+                    filename=filename,
+                    related_type='CDokumente',
+                    field='dokument',
+                    mime_type=mime_type,
+                )
+                new_doc = await espocrm.create_entity('CDokumente', {
+                    'name': filename,
+                    'dokumentId': attachment.get('id'),
+                    'hnr': history_entry.get('hNr') if history_entry else None,
+                    'advowareArt': (history_entry.get('art', 'Schreiben') or 'Schreiben')[:100] if history_entry else 'Schreiben',
+                    'advowareBemerkung': (history_entry.get('text', '') or '')[:255] if history_entry else '',
+                    'dateipfad': windows_file.get('path', ''),
+                    'blake3hash': blake3_hash,
+                    'syncedHash': blake3_hash,
+                    'usn': windows_file.get('usn', 0),
+                    'syncStatus': 'synced',
+                    'lastSyncTimestamp': now,
+                    'cAktenId': akte_id,   # Direct FK to CAkten
+                })
+                doc_id = new_doc.get('id')
+
+                # Link to Akte
+                await espocrm.link_entities('CAkten', akte_id, 'dokumentes', doc_id)
+                results['created'] += 1
+
+                # Trigger preview
+                try:
+                    await ctx.emit('document.generate_preview', {
+                        'entity_id': doc_id,
+                        'entity_type': 'CDokumente',
+                    })
+                except Exception as e:
+                    ctx.logger.warn(f"   ⚠️  Preview trigger failed: {e}")
+
+            elif action.action == 'UPDATE_ESPO':
+                if not windows_file:
+                    ctx.logger.error(f"   ❌ UPDATE_ESPO: no Windows file for hnr {hnr}")
+                    results['errors'] += 1
+                    continue
+
+                content = await watcher.download_file(aktennummer, windows_file.get('relative_path', filename))
+                blake3_hash = compute_blake3(content)
+                mime_type, _ = mimetypes.guess_type(filename)
+                mime_type = mime_type or 'application/octet-stream'
+                now = datetime.now().strftime('%Y-%m-%d %H:%M:%S')
+
+                update_data: Dict[str, Any] = {
+                    'name': filename,
+                    'blake3hash': blake3_hash,
+                    'syncedHash': blake3_hash,
+                    'usn': windows_file.get('usn', 0),
+                    'dateipfad': windows_file.get('path', ''),
+                    'syncStatus': 'synced',
+                    'lastSyncTimestamp': now,
+                }
+                if history_entry:
+                    update_data['hnr'] = history_entry.get('hNr')
+                    update_data['advowareArt'] = (history_entry.get('art', 'Schreiben') or 'Schreiben')[:100]
+                    update_data['advowareBemerkung'] = (history_entry.get('text', '') or '')[:255]
+
+                await espocrm.update_entity('CDokumente', espo_doc['id'], update_data)
+                results['updated'] += 1
+
+                # Mark for re-sync to xAI (hash changed)
+                if espo_doc.get('aiSyncStatus') == 'synced':
+                    await espocrm.update_entity('CDokumente', espo_doc['id'], {
+                        'aiSyncStatus': 'unclean',
+                    })
+
+                try:
+                    await ctx.emit('document.generate_preview', {
+                        'entity_id': espo_doc['id'],
+                        'entity_type': 'CDokumente',
+                    })
+                except Exception as e:
+                    ctx.logger.warn(f"   ⚠️  Preview trigger failed: {e}")
+
+            elif action.action == 'DELETE':
+                if espo_doc:
+                    # Only delete if the HNR is genuinely absent from Advoware History
+                    # (not just absent from Windows – avoids deleting docs whose file
+                    # is temporarily unavailable on the Windows share)
+                    if hnr in history_by_hnr:
+                        ctx.logger.warn(f"   ⚠️  SKIP DELETE hnr={hnr}: still in Advoware History, only missing from Windows")
+                        results['skipped'] += 1
+                    else:
+                        await espocrm.delete_entity('CDokumente', espo_doc['id'])
+                        results['deleted'] += 1
+
+        except Exception as e:
+            ctx.logger.error(f"   ❌ Error for hnr {hnr} ({filename}): {e}")
+            results['errors'] += 1
+
+    # ── Ablage check + Rubrum sync ─────────────────────────────────────
+    try:
+        akte_details = await advoware_service.get_akte(aktennummer)
+        if akte_details:
+            espo_update: Dict[str, Any] = {}
+
+            if akte_details.get('ablage') == 1:
+                ctx.logger.info("📁 Akte marked as ablage → deactivating")
+                espo_update['aktivierungsstatus'] = 'inactive'
+
+            rubrum = akte_details.get('rubrum')
+            if rubrum and rubrum != akte.get('rubrum'):
+                espo_update['rubrum'] = rubrum
+                ctx.logger.info(f"📝 Rubrum synced: {rubrum[:80]}")
+
+            if espo_update:
+                await espocrm.update_entity('CAkten', akte_id, espo_update)
+    except Exception as e:
+        ctx.logger.warn(f"⚠️  Ablage/Rubrum check failed: {e}")
+
+    return results
+
+
+# ─────────────────────────────────────────────────────────────────────────────
+# xAI sync
+# ─────────────────────────────────────────────────────────────────────────────
+
+async def _run_xai_sync(
+    akte: Dict[str, Any],
+    akte_id: str,
+    espocrm,
+    ctx: FlowContext,
+) -> None:
+    from services.xai_service import XAIService
+    from services.xai_upload_utils import XAIUploadUtils
+
+    xai = XAIService(ctx)
+    upload_utils = XAIUploadUtils(ctx)
+
+    ctx.logger.info("")
+    ctx.logger.info("─" * 60)
+    ctx.logger.info("🤖 xAI SYNC")
+    ctx.logger.info("─" * 60)
+
+    try:
+        # ── Ensure collection exists ───────────────────────────────────
+        collection_id = await upload_utils.ensure_collection(akte, xai, espocrm)
+        if not collection_id:
+            ctx.logger.error("❌ Could not obtain xAI collection – aborting xAI sync")
+            await espocrm.update_entity('CAkten', akte_id, {'aiSyncStatus': 'failed'})
+            return
+
+        # ── Load all linked documents ──────────────────────────────────
+        docs_result = await espocrm.list_related('CAkten', akte_id, 'dokumentes')
+        docs = docs_result.get('list', [])
+        ctx.logger.info(f"   Documents to check: {len(docs)}")
+
+        synced = 0
+        skipped = 0
+        failed = 0
+
+        for doc in docs:
+            ok = await upload_utils.sync_document_to_xai(doc, collection_id, xai, espocrm)
+            if ok:
+                if doc.get('aiSyncStatus') == 'synced' and doc.get('aiSyncHash') == doc.get('blake3hash'):
+                    skipped += 1
+                else:
+                    synced += 1
+            else:
+                failed += 1
+
+        ctx.logger.info(f"   ✅ Synced  : {synced}")
+        ctx.logger.info(f"   ⏭️  Skipped : {skipped}")
+        ctx.logger.info(f"   ❌ Failed  : {failed}")
+
+    finally:
+        await xai.close()