feat(B-WS): WebSocket Helpers + Redis Pub/Sub + Error-Handling

B-WS: app/core/ws_helpers.py (NEU) — gemeinsame WebSocket Helpers
- authenticate_ws: Session-Auth für WebSocket (Cookie/Token → User/Tenant)
- check_ws_origin: Origin-Check (delegiert auf verify_ws_origin)
- check_ws_tenant: User-Tenant-Membership-Check
- cleanup_ws_connection: Connection aus Registry entfernen + WS schließen
- start_heartbeat: Background Ping-Task
- send_ws_error: strukturierte Error-Message an Client
- handle_ws_message: Message-Dispatch mit Error-Handling

B-WS: app/core/ws_pubsub.py (NEU) — Redis Pub/Sub für Multi-Worker-Fanout
- publish_to_channel / subscribe_to_channel
- get_tenant_channel / broadcast_to_tenants

B-WS: WebSocketManager + AIUIControlWSManager angepasst
- connect() nutzt authenticate_ws + check_ws_origin + check_ws_tenant
- disconnect() nutzt cleanup_ws_connection + cancelt Heartbeat/PubSub
- broadcast() unterstützt Redis Pub/Sub Fanout

B-ERR-WS: WS Error-Handling in ws_helpers integriert
- send_ws_error für strukturierte Errors
- handle_ws_message fängt Handler-Exceptions

B-WS-TEST: 24 Tests in test_ws_helpers.py — alle grün
- Auth, Origin, Error, Dispatch, Cleanup, Heartbeat, Pub/Sub Roundtrip
- Keine Regression: 47/47 Resilience+Hooks Tests grün

app/plugins/builtins/kommunikation/routes.py

@@ -472,33 +472,29 @@ async def websocket_endpoint(
 
     Authenticates via session cookie. On connect, subscribes user to all their conversations.
     """
-    # Verify Origin header against allowed CORS origins
-    from app.config import get_settings
-    from app.core.auth import get_session_data, get_redis, verify_ws_origin
+    from app.core.db import async_session_maker
+    from app.core.service_container import get_container
 
-    settings = get_settings()
-    if not await verify_ws_origin(websocket):
-        await websocket.close(code=4003, reason="Origin not allowed")
+    # Get WebSocket manager from service container
+    container = get_container()
+    if not container.has("comm_websocket"):
+        await websocket.close(code=4003, reason="Messaging not available")
         return
 
-    session_id = websocket.cookies.get(settings.session_cookie_name)
-    if not session_id:
-        await websocket.close(code=4001, reason="Not authenticated")
-        return
+    ws_manager = container.get("comm_websocket")
 
-    redis = get_redis()
-    session_data = await get_session_data(redis, session_id)
-    if session_data is None:
-        await websocket.close(code=4001, reason="Session expired")
-        return
+    # connect() performs origin check, session auth, tenant check
+    async with async_session_maker() as db:
+        auth = await ws_manager.connect(websocket, db)
+    if auth is None:
+        return  # connection was rejected and closed by ws_helpers
 
-    user_id = session_data["user_id"]
-    tenant_id = session_data["tenant_id"]
+    user_id = auth["user_id"]
+    tenant_id = auth["tenant_id"]
 
     # Plugin-Gate: check if kommunikation plugin is active (global + tenant)
     from app.core.permission_registry import get_permission_registry
     from sqlalchemy import text as sa_text
-    from app.core.db import async_session_maker
     import uuid as _uuid
     try:
         registry = get_permission_registry()
@@ -518,16 +514,6 @@ async def websocket_endpoint(
         await websocket.close(code=4003, reason="Plugin check failed")
         return
 
-    # Get WebSocket manager from service container
-    from app.core.service_container import get_container
-    container = get_container()
-    if not container.has("comm_websocket"):
-        await websocket.close(code=4003, reason="Messaging not available")
-        return
-
-    ws_manager = container.get("comm_websocket")
-    await ws_manager.connect(websocket, user_id)
-
     try:
         while True:
             data = await websocket.receive_text()

app/plugins/builtins/kommunikation/websocket_manager.py

@@ -4,10 +4,25 @@ from __future__ import annotations
 
 import json
 import logging
+import uuid
 from typing import Any
 
 from fastapi import WebSocket
 
+from app.core.ws_helpers import (
+    authenticate_ws,
+    check_ws_origin,
+    check_ws_tenant,
+    cleanup_ws_connection,
+    start_heartbeat,
+)
+from app.core.ws_pubsub import (
+    broadcast_to_tenants,
+    get_tenant_channel,
+    subscribe_to_channel,
+)
+from sqlalchemy.ext.asyncio import AsyncSession
+
 logger = logging.getLogger(__name__)
 
 
@@ -19,26 +34,82 @@ class WebSocketManager:
         self._connections: dict[str, list[WebSocket]] = {}
         # conversation_id (str) → set of user_ids subscribed
         self._subscriptions: dict[str, set[str]] = {}
+        # user_id → list of heartbeat tasks
+        self._heartbeat_tasks: dict[str, list] = {}
+        # user_id → list of pubsub subscriber tasks
+        self._pubsub_tasks: dict[str, list] = {}
 
-    async def connect(self, websocket: WebSocket, user_id: str) -> None:
-        """Accept and register a new WebSocket connection."""
+    async def connect(
+        self,
+        websocket: WebSocket,
+        db: AsyncSession,
+    ) -> dict[str, Any] | None:
+        """Accept, authenticate and register a new WebSocket connection.
+
+        Performs origin check, session authentication and tenant validation.
+        Returns the auth dict (user_id, tenant_id, …) on success, or ``None``
+        if the connection was rejected (already closed).
+        """
+        # Origin / CSRF check
+        if not await check_ws_origin(websocket):
+            return None
+
+        # Session authentication
+        auth = await authenticate_ws(websocket, db)
+        if auth is None:
+            return None
+
+        user_id = auth["user_id"]
+        tenant_id_str = auth["tenant_id"]
+        tenant_id = uuid.UUID(tenant_id_str)
+        user_uuid = uuid.UUID(user_id)
+
+        # Tenant membership check
+        if not await check_ws_tenant(websocket, tenant_id, user_uuid, db):
+            return None
+
+        # Accept the WebSocket
         await websocket.accept()
+
+        # Register connection
         if user_id not in self._connections:
             self._connections[user_id] = []
         self._connections[user_id].append(websocket)
+
+        # Start heartbeat
+        hb_task = await start_heartbeat(websocket)
+        self._heartbeat_tasks.setdefault(user_id, []).append(hb_task)
+
+        # Start Redis Pub/Sub subscriber for tenant-wide fanout
+        channel = get_tenant_channel(tenant_id, "kommunikation")
+        pubsub_task = await subscribe_to_channel(channel, lambda msg: self._on_pubsub_message(user_id, msg))
+        self._pubsub_tasks.setdefault(user_id, []).append(pubsub_task)
+
         logger.debug(f"WebSocket connected: user={user_id}, total={len(self._connections[user_id])}")
+        return auth
+
+    async def _on_pubsub_message(self, user_id: str, msg: dict[str, Any]) -> None:
+        """Handle a message received via Redis Pub/Sub."""
+        await self.send_to_user(user_id, msg)
 
     async def disconnect(self, websocket: WebSocket, user_id: str) -> None:
-        """Remove a WebSocket connection."""
-        conns = self._connections.get(user_id, [])
-        if websocket in conns:
-            conns.remove(websocket)
-        if not conns:
-            self._connections.pop(user_id, None)
-            # Remove from all subscriptions
+        """Remove a WebSocket connection and clean up resources."""
+        # Cancel heartbeat tasks for this user
+        for task in self._heartbeat_tasks.pop(user_id, []):
+            task.cancel()
+        # Cancel pubsub tasks for this user
+        for task in self._pubsub_tasks.pop(user_id, []):
+            task.cancel()
+
+        # Clean up connection registry
+        await cleanup_ws_connection(websocket, user_id, self._connections)
+
+        # Remove from subscriptions if no more connections
+        if user_id not in self._connections:
             for conv_id, users in self._subscriptions.items():
                 users.discard(user_id)
-        logger.debug(f"WebSocket disconnected: user={user_id}, remaining={len(conns)}")
+
+        logger.debug(f"WebSocket disconnected: user={user_id}")
 
     def subscribe(self, conversation_id: str, user_id: str) -> None:
         """Subscribe a user to a conversation's updates."""
@@ -75,10 +146,17 @@ class WebSocketManager:
                 continue
             await self.send_to_user(user_id, message)
 
-    async def broadcast(self, message: dict[str, Any]) -> None:
-        """Broadcast a message to all connected users."""
-        for user_id in list(self._connections.keys()):
-            await self.send_to_user(user_id, message)
+    async def broadcast(self, message: dict[str, Any], tenant_id: uuid.UUID | None = None) -> None:
+        """Broadcast a message to all connected users.
+
+        If *tenant_id* is provided, publishes via Redis Pub/Sub for multi-worker fanout.
+        Otherwise, sends directly to all locally connected users.
+        """
+        if tenant_id is not None:
+            await broadcast_to_tenants(tenant_id, "kommunikation", message)
+        else:
+            for user_id in list(self._connections.keys()):
+                await self.send_to_user(user_id, message)
 
     def get_online_users(self) -> list[str]:
         """Get list of currently connected user IDs."""