diff --git a/app/core/ws_helpers.py b/app/core/ws_helpers.py
new file mode 100644
index 0000000..b4cec27
--- /dev/null
+++ b/app/core/ws_helpers.py
@@ -0,0 +1,184 @@
+"""Shared WebSocket helpers: auth, origin check, tenant check, cleanup, heartbeat, error handling, message dispatch."""
+
+from __future__ import annotations
+
+import asyncio
+import json
+import logging
+import uuid
+from typing import Any, Callable
+
+from sqlalchemy import select
+from sqlalchemy.ext.asyncio import AsyncSession
+from starlette.websockets import WebSocket
+
+from app.core.auth import get_redis, get_session_data, verify_ws_origin
+from app.config import get_settings
+
+logger = logging.getLogger(__name__)
+
+
+async def authenticate_ws(websocket: WebSocket, db: AsyncSession) -> dict[str, Any] | None:
+    """Authenticate a WebSocket connection via session cookie.
+
+    Extracts the session cookie, validates the session in Redis,
+    and returns user/tenant info.  On failure, closes the WebSocket
+    with code 4401 and returns ``None``.
+    """
+    settings = get_settings()
+    session_id = websocket.cookies.get(settings.session_cookie_name)
+    if not session_id:
+        await websocket.close(code=4401, reason="Unauthorized")
+        return None
+
+    redis = get_redis()
+    session_data = await get_session_data(redis, session_id)
+    if session_data is None:
+        await websocket.close(code=4401, reason="Unauthorized")
+        return None
+
+    if not session_data.get("is_active", False):
+        await websocket.close(code=4401, reason="Unauthorized")
+        return None
+
+    return {
+        "user_id": session_data["user_id"],
+        "tenant_id": session_data["tenant_id"],
+        "session_id": session_id,
+        "role": session_data.get("role"),
+        "email": session_data.get("email"),
+        "name": session_data.get("name"),
+        "is_system_admin": session_data.get("is_system_admin", False),
+    }
+
+
+async def check_ws_origin(websocket: WebSocket) -> bool:
+    """Verify the WebSocket origin and CSRF token.
+
+    Delegates to :func:`verify_ws_origin`.  On failure, closes the
+    WebSocket with code 4403 and returns ``False``.
+    """
+    result = await verify_ws_origin(websocket)
+    if not result:
+        await websocket.close(code=4403, reason="Forbidden origin")
+        return False
+    return True
+
+
+async def check_ws_tenant(
+    websocket: WebSocket,
+    tenant_id: uuid.UUID,
+    user_id: uuid.UUID,
+    db: AsyncSession,
+) -> bool:
+    """Verify that *user_id* belongs to *tenant_id*.
+
+    On failure, closes the WebSocket with code 4403 and returns ``False``.
+    """
+    from app.models.user import UserTenant
+
+    result = await db.execute(
+        select(UserTenant).where(
+            UserTenant.user_id == user_id,
+            UserTenant.tenant_id == tenant_id,
+        )
+    )
+    if result.scalar_one_or_none() is None:
+        await websocket.close(code=4403, reason="Forbidden tenant")
+        return False
+    return True
+
+
+async def cleanup_ws_connection(
+    websocket: WebSocket,
+    user_id: str,
+    connection_registry: dict[str, list[WebSocket]],
+) -> None:
+    """Remove a WebSocket from the connection registry and close it cleanly."""
+    conns = connection_registry.get(user_id, [])
+    if websocket in conns:
+        conns.remove(websocket)
+    if not conns:
+        connection_registry.pop(user_id, None)
+    try:
+        await websocket.close()
+    except Exception:
+        logger.debug("WebSocket already closed during cleanup for user %s", user_id)
+
+
+async def start_heartbeat(websocket: WebSocket, interval: int = 30) -> asyncio.Task:
+    """Start a background heartbeat task that sends periodic pings.
+
+    Returns the :class:`asyncio.Task` so the caller can cancel it on disconnect.
+    """
+
+    async def _heartbeat() -> None:
+        while True:
+            try:
+                await asyncio.sleep(interval)
+                await websocket.send_text(json.dumps({"type": "ping"}))
+            except asyncio.CancelledError:
+                break
+            except Exception:
+                logger.debug("Heartbeat stopped — WebSocket likely closed")
+                break
+
+    return asyncio.create_task(_heartbeat())
+
+
+async def send_ws_error(
+    websocket: WebSocket,
+    code: str,
+    detail: str,
+    trace_id: str | None = None,
+) -> None:
+    """Send a structured error message to the WebSocket client."""
+    payload: dict[str, Any] = {
+        "type": "error",
+        "code": code,
+        "detail": detail,
+    }
+    if trace_id is not None:
+        payload["trace_id"] = trace_id
+    try:
+        await websocket.send_text(json.dumps(payload, default=str))
+    except Exception:
+        logger.debug("Failed to send WS error to client")
+
+
+async def handle_ws_message(
+    websocket: WebSocket,
+    message: str,
+    handlers: dict[str, Callable[[WebSocket, dict[str, Any]], Any]],
+) -> None:
+    """Dispatch a WebSocket text message to the appropriate handler.
+
+    *handlers* maps message ``type`` strings to async callables that accept
+    ``(websocket, msg)``.  Unknown types and handler exceptions are
+    reported back to the client via :func:`send_ws_error`.
+    """
+    try:
+        msg = json.loads(message)
+    except (json.JSONDecodeError, TypeError):
+        await send_ws_error(websocket, "invalid_json", "Message is not valid JSON")
+        return
+
+    if not isinstance(msg, dict):
+        await send_ws_error(websocket, "invalid_message", "Message must be a JSON object")
+        return
+
+    msg_type = msg.get("type")
+    if not msg_type:
+        await send_ws_error(websocket, "missing_type", "Message missing 'type' field")
+        return
+
+    handler = handlers.get(msg_type)
+    if handler is None:
+        await send_ws_error(websocket, "unknown_type", f"Unknown message type: {msg_type}")
+        return
+
+    try:
+        await handler(websocket, msg)
+    except Exception as exc:
+        logger.exception("Handler error for message type '%s'", msg_type)
+        await send_ws_error(websocket, "handler_error", str(exc))
diff --git a/app/core/ws_pubsub.py b/app/core/ws_pubsub.py
new file mode 100644
index 0000000..4036376
--- /dev/null
+++ b/app/core/ws_pubsub.py
@@ -0,0 +1,65 @@
+"""Redis Pub/Sub helpers for WebSocket multi-worker fanout."""
+
+from __future__ import annotations
+
+import asyncio
+import json
+import logging
+import uuid
+from typing import Awaitable, Callable
+
+from app.core.auth import get_redis
+
+logger = logging.getLogger(__name__)
+
+
+async def publish_to_channel(channel: str, message: dict) -> None:
+    """Publish a JSON message to a Redis channel."""
+    redis = get_redis()
+    await redis.publish(channel, json.dumps(message, default=str))
+
+
+async def subscribe_to_channel(
+    channel: str,
+    handler: Callable[[dict], Awaitable[None]],
+) -> asyncio.Task:
+    """Subscribe to a Redis channel and call *handler* for every message.
+
+    Returns the :class:`asyncio.Task` so the caller can cancel it on disconnect.
+    """
+
+    async def _subscriber() -> None:
+        redis = get_redis()
+        pubsub = redis.pubsub()
+        await pubsub.subscribe(channel)
+        try:
+            async for raw in pubsub.listen():
+                if raw["type"] == "message":
+                    try:
+                        msg = json.loads(raw["data"])
+                        await handler(msg)
+                    except Exception:
+                        logger.exception("Error in pubsub handler for channel %s", channel)
+        finally:
+            try:
+                await pubsub.unsubscribe(channel)
+                await pubsub.aclose()
+            except Exception:
+                logger.debug("PubSub cleanup error for channel %s", channel)
+
+    return asyncio.create_task(_subscriber())
+
+
+def get_tenant_channel(tenant_id: uuid.UUID, topic: str) -> str:
+    """Return the Redis channel name for a tenant + topic."""
+    return f"ws:{tenant_id}:{topic}"
+
+
+async def broadcast_to_tenants(
+    tenant_id: uuid.UUID,
+    topic: str,
+    message: dict,
+) -> None:
+    """Publish a message to a tenant-specific Redis channel."""
+    channel = get_tenant_channel(tenant_id, topic)
+    await publish_to_channel(channel, message)
diff --git a/app/plugins/builtins/ai_ui_control/routes.py b/app/plugins/builtins/ai_ui_control/routes.py
index b8f7605..c97e8d0 100644
--- a/app/plugins/builtins/ai_ui_control/routes.py
+++ b/app/plugins/builtins/ai_ui_control/routes.py
@@ -205,33 +205,28 @@ async def ai_ui_control_ws(websocket: WebSocket):
 
     Authentication: via session cookie (same pattern as kommunikation plugin).
     """
-    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")
+    container = get_container()
+    if not container.has("ai_ui_control_ws"):
+        await websocket.close(code=4003, reason="AI UI Control 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("ai_ui_control_ws")
 
-    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 ai_ui_control 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()
@@ -251,14 +246,6 @@ async def ai_ui_control_ws(websocket: WebSocket):
         await websocket.close(code=4003, reason="Plugin check failed")
         return
 
-    container = get_container()
-    if not container.has("ai_ui_control_ws"):
-        await websocket.close(code=4003, reason="AI UI Control not available")
-        return
-
-    ws_manager = container.get("ai_ui_control_ws")
-    await ws_manager.connect(websocket, user_id)
-
     try:
         while True:
             data = await websocket.receive_text()
diff --git a/app/plugins/builtins/ai_ui_control/websocket_manager.py b/app/plugins/builtins/ai_ui_control/websocket_manager.py
index efd1284..0f30224 100644
--- a/app/plugins/builtins/ai_ui_control/websocket_manager.py
+++ b/app/plugins/builtins/ai_ui_control/websocket_manager.py
@@ -16,6 +16,20 @@ 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__)
 
 
@@ -36,23 +50,84 @@ class AIUIControlWSManager:
         self._delivered_at: dict[str, float] = {}
         # command_id → user_id (to route feedback)
         self._command_user: dict[str, 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, "ai_ui_control")
+        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"AI UI Control WS 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."""
+        # Forward pubsub messages to the user's connections
+        conns = self._connections.get(user_id, [])
+        text = json.dumps(msg, default=str)
+        for ws in conns:
+            try:
+                await ws.send_text(text)
+            except Exception:
+                logger.warning(f"Failed to send pubsub message to user {user_id}")
 
     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)
-        logger.debug(f"AI UI Control WS disconnected: user={user_id}, remaining={len(conns)}")
+        """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)
+
+        logger.debug(f"AI UI Control WS disconnected: user={user_id}")
 
     async def send_command(self, user_id: str, command: dict[str, Any]) -> str | None:
         """Send a UI command to all frontend connections of a user.
@@ -120,6 +195,24 @@ class AIUIControlWSManager:
         """Get list of currently connected user IDs."""
         return list(self._connections.keys())
 
+    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, "ai_ui_control", message)
+        else:
+            for user_id in list(self._connections.keys()):
+                conns = self._connections.get(user_id, [])
+                text = json.dumps(message, default=str)
+                for ws in conns:
+                    try:
+                        await ws.send_text(text)
+                    except Exception:
+                        logger.warning(f"Failed to broadcast to user {user_id}")
+
     def cleanup_stale(self, timeout_seconds: int = 60) -> None:
         """Remove stale command tracking entries older than timeout."""
         now = time.time()
diff --git a/app/plugins/builtins/kommunikation/routes.py b/app/plugins/builtins/kommunikation/routes.py
index c3c1a3a..0c1b9d5 100644
--- a/app/plugins/builtins/kommunikation/routes.py
+++ b/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()
diff --git a/app/plugins/builtins/kommunikation/websocket_manager.py b/app/plugins/builtins/kommunikation/websocket_manager.py
index 4f25f2d..0c652bc 100644
--- a/app/plugins/builtins/kommunikation/websocket_manager.py
+++ b/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."""
diff --git a/tests/test_ws_helpers.py b/tests/test_ws_helpers.py
new file mode 100644
index 0000000..02cee39
--- /dev/null
+++ b/tests/test_ws_helpers.py
@@ -0,0 +1,500 @@
+"""Tests for WebSocket helpers (ws_helpers) and Redis Pub/Sub (ws_pubsub).
+
+Covers B-WS-TEST + B-ERR-WS-TEST requirements.
+"""
+
+from __future__ import annotations
+
+import asyncio
+import json
+import uuid
+from unittest.mock import AsyncMock, MagicMock, patch
+
+import pytest
+import pytest_asyncio
+
+from app.core.ws_helpers import (
+    authenticate_ws,
+    check_ws_origin,
+    cleanup_ws_connection,
+    handle_ws_message,
+    send_ws_error,
+    start_heartbeat,
+)
+from app.core.ws_pubsub import (
+    broadcast_to_tenants,
+    get_tenant_channel,
+    publish_to_channel,
+    subscribe_to_channel,
+)
+
+
+# ─── Mock WebSocket ───────────────────────────────────────────────────────────
+
+
+class MockWebSocket:
+    """Minimal mock WebSocket for testing WS helpers."""
+
+    def __init__(
+        self,
+        cookies: dict[str, str] | None = None,
+        headers: dict[str, str] | None = None,
+        query_params: dict[str, str] | None = None,
+    ) -> None:
+        self.cookies = cookies or {}
+        self.headers = headers or {}
+        self.query_params = query_params or {}
+        self._closed = False
+        self._close_code: int | None = None
+        self._close_reason: str | None = None
+        self._sent: list[str] = []
+        self._accepted = False
+
+    async def accept(self) -> None:
+        self._accepted = True
+
+    async def close(self, code: int = 1000, reason: str = "") -> None:
+        self._closed = True
+        self._close_code = code
+        self._close_reason = reason
+
+    async def send_text(self, text: str) -> None:
+        if self._closed:
+            raise RuntimeError("WebSocket is closed")
+        self._sent.append(text)
+
+    @property
+    def sent_messages(self) -> list[dict]:
+        return [json.loads(t) for t in self._sent]
+
+
+# ─── authenticate_ws ──────────────────────────────────────────────────────────
+
+
+@pytest.mark.asyncio
+class TestAuthenticateWs:
+    """Tests for authenticate_ws."""
+
+    async def test_authenticate_ws_valid_session(self, db_session, redis_client):
+        """authenticate_ws returns user info when session is valid."""
+        from app.core.auth import create_session, hash_password
+        from app.models.tenant import Tenant
+        from app.models.user import User, UserTenant
+        from app.models.role import Role
+
+        # Create tenant, user, role, membership
+        tenant = Tenant(name="Test Tenant", slug="test-tenant")
+        db_session.add(tenant)
+        await db_session.flush()
+
+        user = User(
+            email="wsauth@test.com",
+            name="WS Auth Test",
+            password_hash=hash_password("TestPass123!"),
+            is_active=True,
+            preferences={},
+        )
+        db_session.add(user)
+        await db_session.flush()
+
+        role = Role(
+            tenant_id=tenant.id,
+            name="admin",
+            permissions={"*": {"*": True}},
+            denied_permissions=[],
+            field_permissions={},
+        )
+        db_session.add(role)
+        await db_session.flush()
+
+        ut = UserTenant(
+            user_id=user.id,
+            tenant_id=tenant.id,
+            is_default=True,
+            role="admin",
+            role_id=role.id,
+        )
+        db_session.add(ut)
+        await db_session.flush()
+        await db_session.commit()
+
+        # Create session
+        session_id, csrf_token = await create_session(
+            db_session, redis_client, user, tenant.id, role="admin"
+        )
+
+        # Create mock WebSocket with session cookie
+        ws = MockWebSocket(cookies={"leocrm_session": session_id})
+
+        auth = await authenticate_ws(ws, db_session)
+        assert auth is not None
+        assert auth["user_id"] == str(user.id)
+        assert auth["tenant_id"] == str(tenant.id)
+        assert auth["session_id"] == session_id
+        assert auth["role"] == "admin"
+        assert ws._closed is False
+
+    async def test_authenticate_ws_missing_cookie(self, db_session):
+        """authenticate_ws closes WS and returns None when no session cookie."""
+        ws = MockWebSocket(cookies={})
+
+        auth = await authenticate_ws(ws, db_session)
+        assert auth is None
+        assert ws._closed is True
+        assert ws._close_code == 4401
+
+    async def test_authenticate_ws_invalid_session(self, db_session):
+        """authenticate_ws closes WS and returns None when session is invalid."""
+        ws = MockWebSocket(cookies={"leocrm_session": "nonexistent-session-id"})
+
+        auth = await authenticate_ws(ws, db_session)
+        assert auth is None
+        assert ws._closed is True
+        assert ws._close_code == 4401
+
+
+# ─── check_ws_origin ──────────────────────────────────────────────────────────
+
+
+@pytest.mark.asyncio
+class TestCheckWsOrigin:
+    """Tests for check_ws_origin."""
+
+    async def test_check_ws_origin_valid(self):
+        """check_ws_origin returns True for valid origin + CSRF."""
+        from app.core.auth import create_session, hash_password
+        from app.models.tenant import Tenant
+        from app.models.user import User, UserTenant
+        from app.models.role import Role
+        from sqlalchemy.ext.asyncio import AsyncSession, async_sessionmaker, create_async_engine
+
+        # We need a full setup with session in Redis for CSRF validation
+        # Use patch to mock verify_ws_origin returning True
+        with patch("app.core.ws_helpers.verify_ws_origin", return_value=True):
+            ws = MockWebSocket()
+            result = await check_ws_origin(ws)
+            assert result is True
+            assert ws._closed is False
+
+    async def test_check_ws_origin_invalid(self):
+        """check_ws_origin closes WS and returns False for invalid origin."""
+        with patch("app.core.ws_helpers.verify_ws_origin", return_value=False):
+            ws = MockWebSocket()
+            result = await check_ws_origin(ws)
+            assert result is False
+            assert ws._closed is True
+            assert ws._close_code == 4403
+
+
+# ─── send_ws_error ────────────────────────────────────────────────────────────
+
+
+@pytest.mark.asyncio
+class TestSendWsError:
+    """Tests for send_ws_error."""
+
+    async def test_send_ws_error_basic(self):
+        """send_ws_error sends structured error message."""
+        ws = MockWebSocket()
+        await send_ws_error(ws, "test_error", "Something went wrong")
+
+        assert len(ws.sent_messages) == 1
+        msg = ws.sent_messages[0]
+        assert msg["type"] == "error"
+        assert msg["code"] == "test_error"
+        assert msg["detail"] == "Something went wrong"
+        assert "trace_id" not in msg
+
+    async def test_send_ws_error_with_trace_id(self):
+        """send_ws_error includes trace_id when provided."""
+        ws = MockWebSocket()
+        await send_ws_error(ws, "test_error", "Failed", trace_id="trace-123")
+
+        msg = ws.sent_messages[0]
+        assert msg["trace_id"] == "trace-123"
+
+    async def test_send_ws_error_on_closed_ws(self):
+        """send_ws_error does not raise when WS is closed."""
+        ws = MockWebSocket()
+        ws._closed = True
+        # Should not raise
+        await send_ws_error(ws, "closed_error", "WS already closed")
+
+
+# ─── handle_ws_message ─────────────────────────────────────────────────────────
+
+
+@pytest.mark.asyncio
+class TestHandleWsMessage:
+    """Tests for handle_ws_message."""
+
+    async def test_handle_ws_message_dispatch(self):
+        """handle_ws_message dispatches to correct handler."""
+        ws = MockWebSocket()
+        called = False
+
+        async def ping_handler(websocket, msg):
+            nonlocal called
+            called = True
+            assert msg["type"] == "ping"
+
+        handlers = {"ping": ping_handler}
+        message = json.dumps({"type": "ping"})
+        await handle_ws_message(ws, message, handlers)
+
+        assert called is True
+
+    async def test_handle_ws_message_unknown_type(self):
+        """handle_ws_message sends error for unknown type."""
+        ws = MockWebSocket()
+        handlers = {"ping": AsyncMock()}
+        message = json.dumps({"type": "unknown_type"})
+        await handle_ws_message(ws, message, handlers)
+
+        assert len(ws.sent_messages) == 1
+        msg = ws.sent_messages[0]
+        assert msg["type"] == "error"
+        assert msg["code"] == "unknown_type"
+
+    async def test_handle_ws_message_handler_exception(self):
+        """handle_ws_message sends error when handler raises exception."""
+        ws = MockWebSocket()
+
+        async def bad_handler(websocket, msg):
+            raise ValueError("Handler crashed")
+
+        handlers = {"ping": bad_handler}
+        message = json.dumps({"type": "ping"})
+        await handle_ws_message(ws, message, handlers)
+
+        assert len(ws.sent_messages) == 1
+        msg = ws.sent_messages[0]
+        assert msg["type"] == "error"
+        assert msg["code"] == "handler_error"
+        assert "Handler crashed" in msg["detail"]
+
+    async def test_handle_ws_message_invalid_json(self):
+        """handle_ws_message sends error for invalid JSON."""
+        ws = MockWebSocket()
+        handlers = {}
+        await handle_ws_message(ws, "not json at all", handlers)
+
+        assert len(ws.sent_messages) == 1
+        msg = ws.sent_messages[0]
+        assert msg["code"] == "invalid_json"
+
+    async def test_handle_ws_message_missing_type(self):
+        """handle_ws_message sends error when type field is missing."""
+        ws = MockWebSocket()
+        handlers = {}
+        message = json.dumps({"data": "no type here"})
+        await handle_ws_message(ws, message, handlers)
+
+        assert len(ws.sent_messages) == 1
+        msg = ws.sent_messages[0]
+        assert msg["code"] == "missing_type"
+
+
+# ─── cleanup_ws_connection ─────────────────────────────────────────────────────
+
+
+@pytest.mark.asyncio
+class TestCleanupWsConnection:
+    """Tests for cleanup_ws_connection."""
+
+    async def test_cleanup_removes_from_registry(self):
+        """cleanup_ws_connection removes WebSocket from registry."""
+        ws1 = MockWebSocket()
+        ws2 = MockWebSocket()
+        registry: dict[str, list] = {"user1": [ws1, ws2]}
+
+        await cleanup_ws_connection(ws1, "user1", registry)
+
+        assert "user1" in registry
+        assert ws1 not in registry["user1"]
+        assert ws2 in registry["user1"]
+        assert len(registry["user1"]) == 1
+
+    async def test_cleanup_removes_empty_user(self):
+        """cleanup_ws_connection removes user entry when no connections left."""
+        ws = MockWebSocket()
+        registry: dict[str, list] = {"user1": [ws]}
+
+        await cleanup_ws_connection(ws, "user1", registry)
+
+        assert "user1" not in registry
+
+    async def test_cleanup_unknown_user(self):
+        """cleanup_ws_connection handles unknown user gracefully."""
+        ws = MockWebSocket()
+        registry: dict[str, list] = {}
+
+        await cleanup_ws_connection(ws, "unknown_user", registry)
+        assert "unknown_user" not in registry
+
+
+# ─── start_heartbeat ───────────────────────────────────────────────────────────
+
+
+@pytest.mark.asyncio
+class TestStartHeartbeat:
+    """Tests for start_heartbeat."""
+
+    async def test_heartbeat_sends_ping(self):
+        """start_heartbeat sends ping messages at interval."""
+        ws = MockWebSocket()
+        task = await start_heartbeat(ws, interval=0)
+
+        # Wait a tiny bit for the first ping
+        await asyncio.sleep(0.05)
+        task.cancel()
+        try:
+            await task
+        except asyncio.CancelledError:
+            pass
+
+        assert len(ws._sent) >= 1
+        msg = ws.sent_messages[0]
+        assert msg["type"] == "ping"
+
+    async def test_heartbeat_cancellable(self):
+        """start_heartbeat task can be cancelled."""
+        ws = MockWebSocket()
+        task = await start_heartbeat(ws, interval=10)
+
+        task.cancel()
+        try:
+            await task
+        except asyncio.CancelledError:
+            pass
+
+        assert task.cancelled() or task.done()
+
+
+# ─── get_tenant_channel ─────────────────────────────────────────────────────────
+
+
+class TestGetTenantChannel:
+    """Tests for get_tenant_channel."""
+
+    def test_channel_naming(self):
+        """get_tenant_channel returns ws:{tenant_id}:{topic}."""
+        tenant_id = uuid.uuid4()
+        channel = get_tenant_channel(tenant_id, "kommunikation")
+        assert channel == f"ws:{tenant_id}:kommunikation"
+
+    def test_channel_naming_different_topic(self):
+        """get_tenant_channel works with different topics."""
+        tenant_id = uuid.uuid4()
+        channel = get_tenant_channel(tenant_id, "ai_ui_control")
+        assert channel == f"ws:{tenant_id}:ai_ui_control"
+
+
+# ─── publish_to_channel + subscribe_to_channel ──────────────────────────────────
+
+
+@pytest.mark.asyncio
+class TestPubSub:
+    """Tests for Redis Pub/Sub helpers."""
+
+    async def test_publish_subscribe_roundtrip(self, redis_client):
+        """publish_to_channel + subscribe_to_channel roundtrip."""
+        received: list[dict] = []
+        channel = f"test-roundtrip-{uuid.uuid4()}"
+        event = asyncio.Event()
+
+        async def handler(msg: dict) -> None:
+            received.append(msg)
+            event.set()
+
+        # Subscribe
+        task = await subscribe_to_channel(channel, handler)
+
+        # Give subscriber a moment to connect
+        await asyncio.sleep(0.1)
+
+        # Publish
+        test_msg = {"type": "test", "data": "hello"}
+        await publish_to_channel(channel, test_msg)
+
+        # Wait for message
+        await asyncio.wait_for(event.wait(), timeout=2.0)
+
+        assert len(received) == 1
+        assert received[0]["type"] == "test"
+        assert received[0]["data"] == "hello"
+
+        # Cleanup
+        task.cancel()
+        try:
+            await task
+        except asyncio.CancelledError:
+            pass
+
+    async def test_broadcast_to_tenants(self, redis_client):
+        """broadcast_to_tenants publishes to the correct tenant channel."""
+        tenant_id = uuid.uuid4()
+        received: list[dict] = []
+        event = asyncio.Event()
+
+        channel = get_tenant_channel(tenant_id, "test_topic")
+
+        async def handler(msg: dict) -> None:
+            received.append(msg)
+            event.set()
+
+        task = await subscribe_to_channel(channel, handler)
+        await asyncio.sleep(0.1)
+
+        test_msg = {"type": "broadcast", "content": "tenant message"}
+        await broadcast_to_tenants(tenant_id, "test_topic", test_msg)
+
+        await asyncio.wait_for(event.wait(), timeout=2.0)
+
+        assert len(received) == 1
+        assert received[0]["type"] == "broadcast"
+        assert received[0]["content"] == "tenant message"
+
+        task.cancel()
+        try:
+            await task
+        except asyncio.CancelledError:
+            pass
+
+    async def test_publish_to_channel_no_subscribers(self, redis_client):
+        """publish_to_channel works even with no subscribers."""
+        channel = f"test-no-sub-{uuid.uuid4()}"
+        await publish_to_channel(channel, {"type": "noop"})
+        # Should not raise
+
+    async def test_subscribe_multiple_messages(self, redis_client):
+        """subscribe_to_channel handler receives multiple messages."""
+        received: list[dict] = []
+        channel = f"test-multi-{uuid.uuid4()}"
+        count_event = asyncio.Event()
+        msg_count = 0
+
+        async def handler(msg: dict) -> None:
+            nonlocal msg_count
+            received.append(msg)
+            msg_count += 1
+            if msg_count >= 3:
+                count_event.set()
+
+        task = await subscribe_to_channel(channel, handler)
+        await asyncio.sleep(0.1)
+
+        for i in range(3):
+            await publish_to_channel(channel, {"type": "msg", "index": i})
+
+        await asyncio.wait_for(count_event.wait(), timeout=3.0)
+
+        assert len(received) == 3
+        assert received[0]["index"] == 0
+        assert received[2]["index"] == 2
+
+        task.cancel()
+        try:
+            await task
+        except asyncio.CancelledError:
+            pass