feat: Unified Messaging System — kommunikation plugin, AI/Proactive/System participants, MessageSidebar, Rich Content Renderer

Phase 1: Backend plugin kommunikation (13 files, 10 tables, REST API, WebSocket, RBAC, DMS Bridge, Participant Registry, Mini-App Registry, Search Provider)
Phase 2: AI plugins as participants (ai_assistant + ai_proactive dock as participants, heartbeat job)
Phase 3: system_notif plugin (system events → chat messages, pinned System room)
Phase 4: Frontend MessageSidebar (replaces AISidebar, same design, comm API client, WebSocket hook, commStore)
Phase 5: Rich Content Block Renderer (11 components: Markdown, HTML, Image, Audio, Video, File, ActionCard, ContactCard, MiniApp, BlockRenderer)
BasePlugin: added services property + _container in on_activate

app/plugins/base.py

@@ -30,6 +30,14 @@ class BasePlugin(ABC):
             raise ValueError(f"{self.__class__.__name__} must define a 'manifest' attribute")
         self._event_handlers: dict[str, Any] = {}
         self._routers: list[APIRouter] = []
+        self._container: Any = None  # ServiceContainer, set during on_activate
+
+    @property
+    def services(self) -> Any:
+        """Access the ServiceContainer after activation."""
+        if self._container is None:
+            raise RuntimeError("Services not available — plugin not activated")
+        return self._container
 
     # ─── Lifecycle Hooks ───
 
@@ -52,6 +60,7 @@ class BasePlugin(ABC):
             handler = self._make_event_handler(event_name)
             self._event_handlers[event_name] = handler
             event_bus.subscribe(event_name, handler)
+        self._container = service_container
 
     async def on_deactivate(
         self, db: AsyncSession, service_container: ServiceContainer, event_bus: EventBus

app/plugins/builtins/ai_assistant/participant_handler.py

@@ -0,0 +1,287 @@
+"""AI Participant Handler — bridges the kommunikation plugin with the AI Assistant.
+
+When a message is received in a conversation that includes the 'ai' participant,
+this handler generates an LLM response using litellm.acompletion (non-streaming)
+and returns it as a new message in the conversation.
+"""
+
+from __future__ import annotations
+
+import logging
+import uuid
+from typing import Any
+
+import litellm
+
+from app.core.db import create_db_session
+from app.plugins.builtins.kommunikation.participant_registry import ParticipantHandler
+
+logger = logging.getLogger(__name__)
+
+
+class AIParticipantHandler(ParticipantHandler):
+    """Handles AI responses as a participant in kommunikation conversations."""
+
+    def __init__(self, container: Any) -> None:
+        self._container = container
+
+    async def on_message_received(
+        self,
+        conversation_id: Any,
+        message: dict[str, Any],
+        conversation: dict[str, Any],
+        mentions: list[str],
+        context: dict[str, Any],
+    ) -> list[dict[str, Any]] | None:
+        """Generate an AI response when the AI is mentioned or in a direct chat.
+
+        Checks:
+        1. 'ai' is in the conversation participants as a participant_type
+        2. '@KI' is in mentions OR the conversation is_direct with only user+ai
+
+        Returns a list with one message dict containing the AI response.
+        """
+        # Check if 'ai' is a participant in this conversation
+        participants = conversation.get("participants", [])
+        ai_is_participant = any(
+            p.get("participant_type") == "ai" for p in participants
+        )
+        if not ai_is_participant:
+            return None
+
+        # Check if AI is mentioned or it's a direct chat with only user + ai
+        ai_mentioned = "KI" in mentions or "ai" in mentions
+        is_direct = conversation.get("is_direct", False)
+
+        if is_direct:
+            # For direct chats, check that only user and ai are participants
+            non_system_participants = [
+                p for p in participants
+                if p.get("participant_type") in ("user", "ai")
+            ]
+            if len(non_system_participants) <= 2:
+                ai_mentioned = True
+
+        if not ai_mentioned:
+            return None
+
+        # Don't respond to our own messages
+        if message.get("sender_type") == "ai":
+            return None
+
+        # Get tenant_id and user_id from context
+        tenant_id_str = context.get("tenant_id") or message.get("tenant_id")
+        if not tenant_id_str:
+            logger.warning("AIParticipantHandler: missing tenant_id in context")
+            return None
+
+        try:
+            tenant_id = uuid.UUID(str(tenant_id_str))
+        except (ValueError, TypeError):
+            logger.warning("AIParticipantHandler: invalid tenant_id: %s", tenant_id_str)
+            return None
+
+        # Build messages from conversation history and generate response
+        try:
+            from app.plugins.builtins.ai_assistant.services import (
+                build_litellm_params,
+                get_default_agent,
+            )
+
+            async with create_db_session(tenant_id) as db:
+                # Get default agent for system prompt and preset configuration
+                agent = await get_default_agent(db, tenant_id)
+
+                # Build message history from conversation messages
+                messages = await self._build_message_history(
+                    db, conversation_id, tenant_id, message
+                )
+
+                if agent:
+                    params, model_id = await build_litellm_params(
+                        db, agent, messages, tenant_id
+                    )
+                else:
+                    # Fallback: use default provider without agent
+                    from app.plugins.builtins.ai_assistant.services import (
+                        get_default_provider,
+                    )
+
+                    provider = await get_default_provider(db, tenant_id)
+                    if not provider:
+                        return [
+                            {
+                                "content": "Kein AI-Provider konfiguriert. Bitte konfigurieren Sie einen Provider in den KI-Einstellungen.",
+                                "content_format": "text",
+                            }
+                        ]
+
+                    model_id = "gpt-4o-mini"
+                    litellm_model = f"{provider.provider_type}/{model_id}"
+                    params: dict[str, Any] = {
+                        "model": litellm_model,
+                        "messages": messages,
+                        "temperature": 0.7,
+                        "max_tokens": 2048,
+                        "stream": False,
+                    }
+                    if provider.api_key:
+                        params["api_key"] = provider.api_key
+                    if provider.base_url:
+                        params["api_base"] = provider.base_url
+
+                # Ensure non-streaming for acompletion
+                params["stream"] = False
+
+                response = await litellm.acompletion(**params)
+                response_text = response.choices[0].message.content or ""
+
+                if not response_text.strip():
+                    response_text = "*(keine Antwort generiert)*"
+
+                return [
+                    {
+                        "content": response_text,
+                        "content_format": "markdown",
+                    }
+                ]
+
+        except Exception as exc:
+            logger.exception("AIParticipantHandler: error generating AI response")
+            return [
+                {
+                    "content": f"Fehler bei der KI-Antwort: {exc}",
+                    "content_format": "text",
+                }
+            ]
+
+    async def _build_message_history(
+        self,
+        db: Any,
+        conversation_id: Any,
+        tenant_id: uuid.UUID,
+        current_message: dict[str, Any],
+    ) -> list[dict[str, str]]:
+        """Build a messages array from the conversation history for the LLM."""
+        from app.plugins.builtins.kommunikation.services import get_messages
+
+        messages: list[dict[str, str]] = []
+
+        # Get conversation history (last 50 messages)
+        try:
+            result = await get_messages(
+                db, tenant_id, uuid.UUID(str(conversation_id)),
+                page=1, page_size=50,
+            )
+            items = result.get("items", [])
+            for item in items:
+                role = "assistant" if item.get("sender_type") == "ai" else "user"
+                content = item.get("content", "")
+                if content:
+                    messages.append({"role": role, "content": content})
+        except Exception:
+            logger.debug("Could not load conversation history, using current message only")
+
+        # Ensure the current message is included
+        current_content = current_message.get("content", "")
+        if current_content and (
+            not messages
+            or messages[-1].get("content") != current_content
+        ):
+            messages.append({"role": "user", "content": current_content})
+
+        return messages
+
+    async def handle_event(self, payload: dict[str, Any]) -> None:
+        """Handle a message.received event from the event bus.
+
+        Extracts conversation_id from the payload, loads the conversation,
+        and calls on_message_received. If a response is generated, sends it
+        back to the conversation.
+        """
+        conversation_id_str = payload.get("conversation_id")
+        tenant_id_str = payload.get("tenant_id")
+        message_content = payload.get("content", "")
+        message_id = payload.get("message_id")
+        sender_type = payload.get("sender_type", "user")
+
+        if not conversation_id_str or not tenant_id_str:
+            logger.warning("AIParticipantHandler.handle_event: missing conversation_id or tenant_id")
+            return
+
+        try:
+            tenant_id = uuid.UUID(str(tenant_id_str))
+            conversation_id = uuid.UUID(str(conversation_id_str))
+        except (ValueError, TypeError):
+            logger.warning("AIParticipantHandler.handle_event: invalid UUID in payload")
+            return
+
+        # Build the message dict
+        message: dict[str, Any] = {
+            "id": message_id,
+            "content": message_content,
+            "sender_type": sender_type,
+            "tenant_id": tenant_id_str,
+        }
+
+        # Load conversation
+        try:
+            from app.plugins.builtins.kommunikation.services import get_conversation
+
+            async with create_db_session(tenant_id) as db:
+                # We need a user_id to load the conversation — use the sender_id from payload
+                user_id_str = payload.get("sender_id")
+                if not user_id_str:
+                    logger.warning("AIParticipantHandler.handle_event: missing sender_id")
+                    return
+
+                user_id = uuid.UUID(str(user_id_str))
+                conversation = await get_conversation(db, tenant_id, conversation_id, user_id)
+
+                if not conversation:
+                    logger.warning("AIParticipantHandler.handle_event: conversation not found")
+                    return
+
+                # Parse mentions from message content
+                from app.plugins.builtins.kommunikation.services import parse_mentions
+
+                mentions = parse_mentions(message_content)
+
+                context: dict[str, Any] = {
+                    "tenant_id": tenant_id_str,
+                    "user_id": user_id_str,
+                }
+
+                # Call on_message_received
+                response_messages = await self.on_message_received(
+                    conversation_id, message, conversation, mentions, context
+                )
+
+                # If we got a response, send it to the conversation
+                if response_messages:
+                    from app.plugins.builtins.kommunikation.services import send_message
+
+                    for resp_msg in response_messages:
+                        await send_message(
+                            db=db,
+                            tenant_id=tenant_id,
+                            conversation_id=conversation_id,
+                            sender_id=None,
+                            sender_type="ai",
+                            content=resp_msg.get("content", ""),
+                            content_format=resp_msg.get("content_format", "text"),
+                            blocks=resp_msg.get("blocks"),
+                        )
+
+                    await db.commit()
+
+        except Exception:
+            logger.exception("AIParticipantHandler.handle_event: error processing event")
+
+    def get_participant_info(self) -> dict[str, Any]:
+        """Return metadata about this participant."""
+        return {
+            "display_name": "KI Assistent",
+            "capabilities": ["chat", "tools", "streaming"],
+            "description": "KI Assistent für Chat und Tool-Nutzung",
+        }

app/plugins/builtins/ai_assistant/plugin.py

@@ -42,12 +42,78 @@ class AIAssistantPlugin(BasePlugin):
         is_core=True,
     )
 
+    def __init__(self) -> None:
+        super().__init__()
+        self._ai_handler = None
+        self._msg_handler = None
+
     async def on_install(self, db, service_container) -> None:
         """Seed default provider and agent."""
         from app.plugins.builtins.ai_assistant.services import seed_defaults
 
         await seed_defaults(db)
 
+    async def on_activate(self, db, service_container, event_bus) -> None:
+        """Activate plugin: register context tools and participant handler."""
+        await super().on_activate(db, service_container, event_bus)
+
+        # Register as participant in the kommunikation system
+        try:
+            from app.plugins.builtins.ai_assistant.participant_handler import (
+                AIParticipantHandler,
+            )
+            from app.plugins.builtins.kommunikation.participant_registry import (
+                get_participant_registry,
+            )
+
+            self._ai_handler = AIParticipantHandler(service_container)
+            get_participant_registry().register("ai", self._ai_handler)
+            logger.info("AI Assistant registered as participant 'ai'")
+        except Exception:
+            logger.exception("Failed to register AI Assistant as participant")
+
+        # Subscribe to message.received events
+        try:
+            self._msg_handler = self._on_message_received
+            event_bus.subscribe("message.received", self._msg_handler)
+            logger.info("AI Assistant subscribed to message.received events")
+        except Exception:
+            logger.exception("Failed to subscribe to message.received events")
+
+    async def _on_message_received(self, payload: dict[str, Any]) -> None:
+        """Handle message.received event by delegating to the AI participant handler."""
+        if self._ai_handler is None:
+            return
+        try:
+            await self._ai_handler.handle_event(payload)
+        except Exception:
+            logger.exception("Error in AI participant handler for message.received")
+
+    async def on_deactivate(self, db, service_container, event_bus) -> None:
+        """Deactivate plugin: unregister participant and event subscriptions."""
+        # Unregister from participant registry
+        try:
+            from app.plugins.builtins.kommunikation.participant_registry import (
+                get_participant_registry,
+            )
+
+            get_participant_registry().unregister("ai")
+            logger.info("AI Assistant unregistered as participant 'ai'")
+        except Exception:
+            logger.exception("Failed to unregister AI Assistant as participant")
+
+        # Unsubscribe from message.received events
+        if self._msg_handler:
+            try:
+                event_bus.unsubscribe("message.received", self._msg_handler)
+            except Exception:
+                logger.exception("Failed to unsubscribe from message.received events")
+            self._msg_handler = None
+
+        self._ai_handler = None
+
+        await super().on_deactivate(db, service_container, event_bus)
+
     def get_notification_types(self) -> list[dict[str, Any]]:
         return [
             {

app/plugins/builtins/ai_proactive/jobs.py

@@ -314,3 +314,84 @@ async def deep_analysis(
             entity_type,
             entity_id,
         )
+
+
+# ─── Heartbeat Job ───
+
+
+async def heartbeat(ctx: dict[str, Any], user_id: str, tenant_id: str) -> None:
+    """Heartbeat job for the AI Proactive plugin.
+
+    Runs every 5 minutes (scheduled by the plugin on activation).
+    Posts a status message to the 'Live KI' room in the kommunikation system.
+    """
+    try:
+        uid = uuid.UUID(user_id)
+        tid = uuid.UUID(tenant_id)
+    except (ValueError, TypeError):
+        logger.warning("heartbeat: invalid UUID parameters (user_id=%s, tenant_id=%s)", user_id, tenant_id)
+        return
+
+    try:
+        from app.core.db import create_db_session
+        from app.plugins.builtins.kommunikation.services import (
+            create_plugin_room,
+            send_message,
+        )
+
+        async with create_db_session(tid) as db:
+            # Create or get the 'Live KI' room for this user
+            room = await create_plugin_room(
+                db,
+                tid,
+                uid,
+                plugin_name="ai_proactive",
+                title="Live KI",
+                participant_type="ai_proactive",
+                user_role="member",
+            )
+
+            conversation_id_str = room.get("id")
+            if not conversation_id_str:
+                logger.warning("heartbeat: could not create/get Live KI room")
+                return
+
+            conversation_id = uuid.UUID(conversation_id_str)
+
+            # Gather some stats for the status message
+            from sqlalchemy import func, select
+
+            from app.models.contact import Contact
+
+            contact_count_result = await db.execute(
+                select(func.count()).select_from(Contact).where(
+                    Contact.tenant_id == tid,
+                    Contact.deleted_at.is_(None),
+                )
+            )
+            contact_count = contact_count_result.scalar() or 0
+
+            # Build status message
+            from datetime import datetime, timezone
+
+            now_str = datetime.now(timezone.utc).strftime("%H:%M:%S")
+            status_content = (
+                f"**System aktiv** — überwacht {contact_count} Kontakte\n"
+                f"_Letztes Update: {now_str}_"
+            )
+
+            await send_message(
+                db=db,
+                tenant_id=tid,
+                conversation_id=conversation_id,
+                sender_id=None,
+                sender_type="ai_proactive",
+                content=status_content,
+                content_format="markdown",
+            )
+
+            await db.commit()
+            logger.info("heartbeat: posted status to Live KI room for user %s", user_id)
+
+    except Exception:
+        logger.exception("heartbeat: error posting status message")

app/plugins/builtins/ai_proactive/participant_handler.py

@@ -0,0 +1,232 @@
+"""AI Proactive Participant Handler — bridges the kommunikation plugin with the proactive AI.
+
+When a message is received in a conversation that includes the 'ai_proactive' participant,
+this handler generates a proactive suggestion based on the message context.
+"""
+
+from __future__ import annotations
+
+import logging
+import uuid
+from typing import Any
+
+from app.core.db import create_db_session
+from app.plugins.builtins.kommunikation.participant_registry import ParticipantHandler
+
+logger = logging.getLogger(__name__)
+
+
+class AIProactiveParticipantHandler(ParticipantHandler):
+    """Handles proactive AI suggestions as a participant in kommunikation conversations."""
+
+    def __init__(self, container: Any) -> None:
+        self._container = container
+
+    async def on_message_received(
+        self,
+        conversation_id: Any,
+        message: dict[str, Any],
+        conversation: dict[str, Any],
+        mentions: list[str],
+        context: dict[str, Any],
+    ) -> list[dict[str, Any]] | None:
+        """Generate a proactive suggestion when ai_proactive is a participant.
+
+        Checks if 'ai_proactive' is in the conversation participants as a
+        participant_type. If yes, generates a suggestion based on the message.
+
+        Returns a list with one message dict containing the suggestion as
+        an action card, or None on error.
+        """
+        # Check if 'ai_proactive' is a participant in this conversation
+        participants = conversation.get("participants", [])
+        ai_proactive_is_participant = any(
+            p.get("participant_type") == "ai_proactive" for p in participants
+        )
+        if not ai_proactive_is_participant:
+            return None
+
+        # Don't respond to our own messages
+        if message.get("sender_type") == "ai_proactive":
+            return None
+
+        # Get tenant_id and user_id from context
+        tenant_id_str = context.get("tenant_id") or message.get("tenant_id")
+        user_id_str = context.get("user_id")
+
+        if not tenant_id_str:
+            logger.warning("AIProactiveParticipantHandler: missing tenant_id in context")
+            return None
+
+        try:
+            tenant_id = uuid.UUID(str(tenant_id_str))
+            user_id = uuid.UUID(str(user_id_str)) if user_id_str else None
+        except (ValueError, TypeError):
+            logger.warning("AIProactiveParticipantHandler: invalid UUID in context")
+            return None
+
+        # Generate suggestion using the existing generate_suggestion function
+        try:
+            from app.plugins.builtins.ai_proactive.services import (
+                generate_suggestion,
+                get_user_settings,
+            )
+
+            async with create_db_session(tenant_id) as db:
+                # Get user settings for the proactive AI
+                if user_id:
+                    settings = await get_user_settings(db, tenant_id, user_id)
+                else:
+                    # Create minimal default settings if no user_id
+                    from app.plugins.builtins.ai_proactive.models import ProactiveSettings
+
+                    settings = ProactiveSettings(
+                        tenant_id=tenant_id,
+                        user_id=user_id or uuid.uuid4(),
+                        enabled=True,
+                        suggestion_categories=["mail", "tasks", "contacts", "companies", "insights"],
+                        confidence_threshold=0.5,
+                        rate_limit_seconds=10,
+                        model="ollama/deepseek-v4-flash",
+                    )
+
+                if not settings.enabled:
+                    return None
+
+                # Build context data from the message
+                context_data: dict[str, Any] = {
+                    "entity_type": "message",
+                    "message": message.get("content", ""),
+                    "conversation_id": str(conversation_id),
+                    "sender_type": message.get("sender_type", "user"),
+                }
+
+                # Generate suggestion via LLM
+                suggestion = await generate_suggestion(
+                    context_data, settings, db=db, tenant_id=tenant_id
+                )
+
+                if not suggestion:
+                    return None
+
+                # Build the response message with an action card block
+                suggestion_text = suggestion.get("content", "")
+                title = suggestion.get("title", "KI Vorschlag")
+                suggestion_type = suggestion.get("suggestion_type", "info")
+                confidence = suggestion.get("confidence", 0.5)
+                actions = suggestion.get("actions", [])
+
+                return [
+                    {
+                        "content": suggestion_text,
+                        "content_format": "markdown",
+                        "blocks": [
+                            {
+                                "block_type": "action_card",
+                                "block_data": {
+                                    "title": title,
+                                    "suggestion_type": suggestion_type,
+                                    "confidence": confidence,
+                                    "actions": actions,
+                                },
+                            }
+                        ],
+                    }
+                ]
+
+        except Exception:
+            logger.exception("AIProactiveParticipantHandler: error generating suggestion")
+            return None
+
+    async def handle_event(self, payload: dict[str, Any]) -> None:
+        """Handle a message.received event from the event bus.
+
+        Extracts conversation_id from the payload, loads the conversation,
+        and calls on_message_received. If a response is generated, sends it
+        back to the conversation.
+        """
+        conversation_id_str = payload.get("conversation_id")
+        tenant_id_str = payload.get("tenant_id")
+        message_content = payload.get("content", "")
+        message_id = payload.get("message_id")
+        sender_type = payload.get("sender_type", "user")
+        sender_id_str = payload.get("sender_id")
+
+        if not conversation_id_str or not tenant_id_str:
+            logger.warning("AIProactiveParticipantHandler.handle_event: missing conversation_id or tenant_id")
+            return
+
+        try:
+            tenant_id = uuid.UUID(str(tenant_id_str))
+            conversation_id = uuid.UUID(str(conversation_id_str))
+        except (ValueError, TypeError):
+            logger.warning("AIProactiveParticipantHandler.handle_event: invalid UUID in payload")
+            return
+
+        # Build the message dict
+        message: dict[str, Any] = {
+            "id": message_id,
+            "content": message_content,
+            "sender_type": sender_type,
+            "tenant_id": tenant_id_str,
+        }
+
+        # Load conversation
+        try:
+            from app.plugins.builtins.kommunikation.services import get_conversation
+
+            async with create_db_session(tenant_id) as db:
+                if not sender_id_str:
+                    logger.warning("AIProactiveParticipantHandler.handle_event: missing sender_id")
+                    return
+
+                user_id = uuid.UUID(str(sender_id_str))
+                conversation = await get_conversation(db, tenant_id, conversation_id, user_id)
+
+                if not conversation:
+                    logger.warning("AIProactiveParticipantHandler.handle_event: conversation not found")
+                    return
+
+                # Parse mentions from message content
+                from app.plugins.builtins.kommunikation.services import parse_mentions
+
+                mentions = parse_mentions(message_content)
+
+                context: dict[str, Any] = {
+                    "tenant_id": tenant_id_str,
+                    "user_id": sender_id_str,
+                }
+
+                # Call on_message_received
+                response_messages = await self.on_message_received(
+                    conversation_id, message, conversation, mentions, context
+                )
+
+                # If we got a response, send it to the conversation
+                if response_messages:
+                    from app.plugins.builtins.kommunikation.services import send_message
+
+                    for resp_msg in response_messages:
+                        await send_message(
+                            db=db,
+                            tenant_id=tenant_id,
+                            conversation_id=conversation_id,
+                            sender_id=None,
+                            sender_type="ai_proactive",
+                            content=resp_msg.get("content", ""),
+                            content_format=resp_msg.get("content_format", "text"),
+                            blocks=resp_msg.get("blocks"),
+                        )
+
+                    await db.commit()
+
+        except Exception:
+            logger.exception("AIProactiveParticipantHandler.handle_event: error processing event")
+
+    def get_participant_info(self) -> dict[str, Any]:
+        """Return metadata about this participant."""
+        return {
+            "display_name": "Live KI",
+            "capabilities": ["proactive", "context_aware", "heartbeat"],
+            "description": "Proaktive KI mit Kontextbewusstsein und Heartbeat",
+        }

app/plugins/builtins/ai_proactive/plugin.py

@@ -45,8 +45,12 @@ class AIProactivePlugin(BasePlugin):
         is_core=False,
     )
 
+    def __init__(self) -> None:
+        super().__init__()
+        self._proactive_handler = None
+
     async def on_activate(self, db, service_container, event_bus) -> None:
-        """Register context tools and subscribe to events."""
+        """Register context tools, subscribe to events, and register as participant."""
         await super().on_activate(db, service_container, event_bus)
         try:
             from app.plugins.builtins.ai_proactive.context_tools import (
@@ -61,8 +65,36 @@ class AIProactivePlugin(BasePlugin):
         except Exception:
             logger.exception("Failed to register AI Proactive context tools")
 
+        # Register as participant in the kommunikation system
+        try:
+            from app.plugins.builtins.ai_proactive.participant_handler import (
+                AIProactiveParticipantHandler,
+            )
+            from app.plugins.builtins.kommunikation.participant_registry import (
+                get_participant_registry,
+            )
+
+            self._proactive_handler = AIProactiveParticipantHandler(service_container)
+            get_participant_registry().register("ai_proactive", self._proactive_handler)
+            logger.info("AI Proactive registered as participant 'ai_proactive'")
+        except Exception:
+            logger.exception("Failed to register AI Proactive as participant")
+
     async def on_deactivate(self, db, service_container, event_bus) -> None:
-        """Unregister tools and event listeners."""
+        """Unregister tools, event listeners, and participant."""
+        # Unregister from participant registry
+        try:
+            from app.plugins.builtins.kommunikation.participant_registry import (
+                get_participant_registry,
+            )
+
+            get_participant_registry().unregister("ai_proactive")
+            logger.info("AI Proactive unregistered as participant 'ai_proactive'")
+        except Exception:
+            logger.exception("Failed to unregister AI Proactive as participant")
+
+        self._proactive_handler = None
+
         try:
             from app.plugins.builtins.ai_assistant.tool_registry import (
                 get_tool_registry,

app/plugins/builtins/kommunikation/content_types.py

@@ -0,0 +1,82 @@
+"""Content block type definitions for rich content in messages."""
+
+from __future__ import annotations
+
+from typing import Any
+
+
+# Known block types and their expected schema
+BLOCK_TYPES: dict[str, dict[str, Any]] = {
+    "text": {
+        "description": "Plain text fallback",
+        "fields": {"text": "str"},
+    },
+    "markdown": {
+        "description": "Markdown formatted text",
+        "fields": {"markdown": "str"},
+    },
+    "html": {
+        "description": "Sanitized HTML content",
+        "fields": {"html": "str"},
+    },
+    "image": {
+        "description": "Image attachment",
+        "fields": {"url": "str", "alt": "str", "width": "int?"},
+    },
+    "audio": {
+        "description": "Audio file",
+        "fields": {"url": "str", "duration": "int?", "waveform": "list?"},
+    },
+    "video": {
+        "description": "Video file",
+        "fields": {"url": "str", "duration": "int?", "thumbnail": "str?"},
+    },
+    "file": {
+        "description": "Generic file attachment",
+        "fields": {"url": "str", "name": "str", "size": "int?"},
+    },
+    "action_card": {
+        "description": "Interactive card with buttons",
+        "fields": {
+            "title": "str",
+            "body": "str",
+            "actions": "list[dict]",  # [{label, action, type}]
+        },
+    },
+    "contact_card": {
+        "description": "Contact reference card",
+        "fields": {"contact_id": "str", "name": "str"},
+    },
+    "miniapp": {
+        "description": "Embedded mini-app",
+        "fields": {"app_id": "str", "config": "dict?"},
+    },
+}
+
+
+def validate_block(block_type: str, block_data: dict[str, Any]) -> bool:
+    """Validate that a block has the required fields for its type.
+
+    Returns True if valid, False otherwise.
+    Unknown block types are allowed (forward-compatible) but logged.
+    """
+    if block_type not in BLOCK_TYPES:
+        # Unknown types are allowed — forward compatible
+        return True
+
+    required_fields = BLOCK_TYPES[block_type].get("fields", {})
+    for field_name, field_type in required_fields.items():
+        if field_type.endswith("?"):
+            continue  # Optional field
+        if field_name not in block_data:
+            return False
+
+    return True
+
+
+def list_block_types() -> list[dict[str, Any]]:
+    """List all known block types for frontend reference."""
+    return [
+        {"block_type": bt, "description": info["description"], "fields": info["fields"]}
+        for bt, info in BLOCK_TYPES.items()
+    ]

app/plugins/builtins/kommunikation/dms_bridge.py

@@ -0,0 +1,187 @@
+"""DMS Bridge — integrates with the DMS plugin for file storage."""
+
+from __future__ import annotations
+
+import logging
+import os
+import uuid
+from typing import Any
+
+from fastapi import UploadFile
+from sqlalchemy import select
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from app.plugins.builtins.dms.models import File as DmsFile, Folder
+
+logger = logging.getLogger(__name__)
+
+DMS_STORAGE_BASE = os.environ.get("DMS_STORAGE_BASE", "/tmp/dms")
+COMM_FOLDER_NAME = "_kommunikation"
+MAX_DIRECT_UPLOAD = 100 * 1024 * 1024  # 100 MB — larger files must be DMS references
+
+
+class DmsBridge:
+    """Bridge to the DMS plugin for attachment storage."""
+
+    @staticmethod
+    async def ensure_comm_folder(
+        db: AsyncSession,
+        tenant_id: uuid.UUID,
+        user_id: uuid.UUID,
+    ) -> Folder:
+        """Ensure the _kommunikation root folder exists in DMS."""
+        result = await db.execute(
+            select(Folder).where(
+                Folder.name == COMM_FOLDER_NAME,
+                Folder.parent_id.is_(None),
+                Folder.tenant_id == tenant_id,
+                Folder.deleted_at.is_(None),
+            )
+        )
+        folder = result.scalar_one_or_none()
+        if folder is None:
+            folder = Folder(
+                tenant_id=tenant_id,
+                name=COMM_FOLDER_NAME,
+                parent_id=None,
+                created_by=user_id,
+            )
+            db.add(folder)
+            await db.flush()
+        return folder
+
+    @staticmethod
+    async def ensure_conversation_folder(
+        db: AsyncSession,
+        tenant_id: uuid.UUID,
+        user_id: uuid.UUID,
+        conversation_id: uuid.UUID,
+    ) -> Folder:
+        """Ensure a sub-folder for a specific conversation exists."""
+        root_folder = await DmsBridge.ensure_comm_folder(db, tenant_id, user_id)
+        conv_name = str(conversation_id)
+        result = await db.execute(
+            select(Folder).where(
+                Folder.name == conv_name,
+                Folder.parent_id == root_folder.id,
+                Folder.tenant_id == tenant_id,
+                Folder.deleted_at.is_(None),
+            )
+        )
+        folder = result.scalar_one_or_none()
+        if folder is None:
+            folder = Folder(
+                tenant_id=tenant_id,
+                name=conv_name,
+                parent_id=root_folder.id,
+                created_by=user_id,
+            )
+            db.add(folder)
+            await db.flush()
+        return folder
+
+    @staticmethod
+    async def store_attachment(
+        db: AsyncSession,
+        tenant_id: uuid.UUID,
+        conversation_id: uuid.UUID,
+        user_id: uuid.UUID,
+        file: UploadFile,
+    ) -> dict[str, Any]:
+        """Store an uploaded file in the DMS under _kommunikation/{conversation_id}/.
+
+        Returns dict with file_id, file_name, file_type, file_size.
+        """
+        # Check size limit
+        content = await file.read()
+        file_size = len(content)
+
+        if file_size > MAX_DIRECT_UPLOAD:
+            raise ValueError(
+                f"File size {file_size} exceeds direct upload limit ({MAX_DIRECT_UPLOAD} bytes). "
+                f"Use DMS reference instead."
+            )
+
+        # Ensure conversation folder
+        folder = await DmsBridge.ensure_conversation_folder(
+            db, tenant_id, user_id, conversation_id
+        )
+
+        # Save file to disk
+        file_id = uuid.uuid4()
+        file_ext = os.path.splitext(file.filename or "")[1] or ""
+        storage_path = os.path.join(
+            DMS_STORAGE_BASE,
+            str(tenant_id),
+            str(folder.id),
+            f"{file_id}{file_ext}",
+        )
+        os.makedirs(os.path.dirname(storage_path), exist_ok=True)
+        with open(storage_path, "wb") as f:
+            f.write(content)
+
+        # Create DMS file record
+        dms_file = DmsFile(
+            tenant_id=tenant_id,
+            name=file.filename or f"{file_id}",
+            folder_id=folder.id,
+            uploaded_by=user_id,
+            mime_type=file.content_type or "application/octet-stream",
+            size_bytes=file_size,
+            storage_path=storage_path,
+        )
+        db.add(dms_file)
+        await db.flush()
+
+        return {
+            "file_id": str(dms_file.id),
+            "file_name": dms_file.name,
+            "file_type": dms_file.mime_type,
+            "file_size": dms_file.size_bytes,
+            "file_source": "comm",
+        }
+
+    @staticmethod
+    async def reference_external_file(
+        db: AsyncSession,
+        tenant_id: uuid.UUID,
+        file_id: uuid.UUID,
+    ) -> dict[str, Any] | None:
+        """Reference an existing DMS file without copying it.
+
+        Returns dict with file metadata or None if file not found.
+        """
+        result = await db.execute(
+            select(DmsFile).where(
+                DmsFile.id == file_id,
+                DmsFile.tenant_id == tenant_id,
+                DmsFile.deleted_at.is_(None),
+            )
+        )
+        dms_file = result.scalar_one_or_none()
+        if dms_file is None:
+            return None
+
+        return {
+            "file_id": str(dms_file.id),
+            "file_name": dms_file.name,
+            "file_type": dms_file.mime_type,
+            "file_size": dms_file.size_bytes,
+            "file_source": "dms",
+        }
+
+    @staticmethod
+    async def get_file(
+        db: AsyncSession,
+        tenant_id: uuid.UUID,
+        file_id: uuid.UUID,
+    ) -> DmsFile | None:
+        """Get a DMS file by ID."""
+        result = await db.execute(
+            select(DmsFile).where(
+                DmsFile.id == file_id,
+                DmsFile.tenant_id == tenant_id,
+                DmsFile.deleted_at.is_(None),
+            )
+        )
+        return result.scalar_one_or_none()

app/plugins/builtins/kommunikation/migrations/0001_initial.sql

@@ -0,0 +1,160 @@
+-- kommunikation plugin initial migration: creates all 10 tables
+
+CREATE TABLE IF NOT EXISTS comm_conversations (
+    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    tenant_id UUID NOT NULL,
+    title VARCHAR(255),
+    title_set_by UUID,
+    is_pinned BOOLEAN NOT NULL DEFAULT FALSE,
+    is_locked BOOLEAN NOT NULL DEFAULT FALSE,
+    locked_by VARCHAR(100),
+    is_direct BOOLEAN NOT NULL DEFAULT FALSE,
+    is_archived BOOLEAN NOT NULL DEFAULT FALSE,
+    created_by UUID,
+    created_by_type VARCHAR(20) NOT NULL DEFAULT 'user',
+    last_msg_at TIMESTAMPTZ,
+    last_msg_preview TEXT,
+    last_msg_sender_type VARCHAR(50),
+    metadata JSONB NOT NULL DEFAULT '{}',
+    created_at TIMESTAMPTZ NOT NULL DEFAULT now(),
+    updated_at TIMESTAMPTZ NOT NULL DEFAULT now(),
+    deleted_at TIMESTAMPTZ
+);
+CREATE INDEX IF NOT EXISTS ix_comm_conversations_tenant ON comm_conversations(tenant_id);
+CREATE INDEX IF NOT EXISTS ix_comm_conversations_tenant_pinned ON comm_conversations(tenant_id, is_pinned);
+CREATE INDEX IF NOT EXISTS ix_comm_conversations_last_msg ON comm_conversations(tenant_id, last_msg_at DESC);
+
+CREATE TABLE IF NOT EXISTS comm_participants (
+    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    tenant_id UUID NOT NULL,
+    conversation_id UUID NOT NULL REFERENCES comm_conversations(id) ON DELETE CASCADE,
+    participant_id UUID,
+    participant_type VARCHAR(50) NOT NULL,
+    display_name VARCHAR(255),
+    role VARCHAR(20) NOT NULL DEFAULT 'member',
+    joined_at TIMESTAMPTZ NOT NULL DEFAULT now(),
+    left_at TIMESTAMPTZ,
+    created_at TIMESTAMPTZ NOT NULL DEFAULT now(),
+    updated_at TIMESTAMPTZ NOT NULL DEFAULT now(),
+    deleted_at TIMESTAMPTZ,
+    UNIQUE(conversation_id, participant_id, participant_type)
+);
+CREATE INDEX IF NOT EXISTS ix_comm_participants_tenant_conv ON comm_participants(tenant_id, conversation_id);
+CREATE INDEX IF NOT EXISTS ix_comm_participants_tenant_user ON comm_participants(tenant_id, participant_id);
+
+CREATE TABLE IF NOT EXISTS comm_messages (
+    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    tenant_id UUID NOT NULL,
+    conversation_id UUID NOT NULL REFERENCES comm_conversations(id) ON DELETE CASCADE,
+    sender_id UUID,
+    sender_type VARCHAR(50) NOT NULL,
+    content TEXT NOT NULL DEFAULT '',
+    content_format VARCHAR(20) NOT NULL DEFAULT 'text',
+    metadata JSONB NOT NULL DEFAULT '{}',
+    reply_to_id UUID REFERENCES comm_messages(id) ON DELETE SET NULL,
+    is_pinned BOOLEAN NOT NULL DEFAULT FALSE,
+    read_at TIMESTAMPTZ,
+    edited_at TIMESTAMPTZ,
+    created_at TIMESTAMPTZ NOT NULL DEFAULT now(),
+    updated_at TIMESTAMPTZ NOT NULL DEFAULT now(),
+    deleted_at TIMESTAMPTZ
+);
+CREATE INDEX IF NOT EXISTS ix_comm_messages_tenant_conv ON comm_messages(tenant_id, conversation_id, created_at);
+CREATE INDEX IF NOT EXISTS ix_comm_messages_tenant_sender ON comm_messages(tenant_id, sender_id);
+
+CREATE TABLE IF NOT EXISTS comm_message_blocks (
+    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    tenant_id UUID NOT NULL,
+    message_id UUID NOT NULL REFERENCES comm_messages(id) ON DELETE CASCADE,
+    block_type VARCHAR(50) NOT NULL,
+    block_data JSONB NOT NULL,
+    sort_order INTEGER NOT NULL DEFAULT 0,
+    created_at TIMESTAMPTZ NOT NULL DEFAULT now(),
+    updated_at TIMESTAMPTZ NOT NULL DEFAULT now(),
+    deleted_at TIMESTAMPTZ
+);
+CREATE INDEX IF NOT EXISTS ix_comm_blocks_tenant_msg ON comm_message_blocks(tenant_id, message_id);
+
+CREATE TABLE IF NOT EXISTS comm_message_attachments (
+    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    tenant_id UUID NOT NULL,
+    message_id UUID NOT NULL REFERENCES comm_messages(id) ON DELETE CASCADE,
+    file_id UUID,
+    file_source VARCHAR(10) NOT NULL DEFAULT 'comm',
+    file_name VARCHAR(255) NOT NULL,
+    file_type VARCHAR(255) NOT NULL,
+    file_size INTEGER,
+    thumbnail_path VARCHAR(1024),
+    metadata JSONB NOT NULL DEFAULT '{}',
+    created_at TIMESTAMPTZ NOT NULL DEFAULT now(),
+    updated_at TIMESTAMPTZ NOT NULL DEFAULT now(),
+    deleted_at TIMESTAMPTZ
+);
+CREATE INDEX IF NOT EXISTS ix_comm_attachments_tenant_msg ON comm_message_attachments(tenant_id, message_id);
+
+CREATE TABLE IF NOT EXISTS comm_message_reactions (
+    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    tenant_id UUID NOT NULL,
+    message_id UUID NOT NULL REFERENCES comm_messages(id) ON DELETE CASCADE,
+    user_id UUID NOT NULL,
+    emoji VARCHAR(50) NOT NULL,
+    created_at TIMESTAMPTZ NOT NULL DEFAULT now(),
+    updated_at TIMESTAMPTZ NOT NULL DEFAULT now(),
+    deleted_at TIMESTAMPTZ,
+    UNIQUE(message_id, user_id, emoji)
+);
+CREATE INDEX IF NOT EXISTS ix_comm_reactions_tenant_msg ON comm_message_reactions(tenant_id, message_id);
+
+CREATE TABLE IF NOT EXISTS comm_message_reads (
+    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    tenant_id UUID NOT NULL,
+    conversation_id UUID NOT NULL REFERENCES comm_conversations(id) ON DELETE CASCADE,
+    user_id UUID NOT NULL,
+    last_read_msg_id UUID REFERENCES comm_messages(id) ON DELETE SET NULL,
+    last_read_at TIMESTAMPTZ NOT NULL DEFAULT now(),
+    created_at TIMESTAMPTZ NOT NULL DEFAULT now(),
+    updated_at TIMESTAMPTZ NOT NULL DEFAULT now(),
+    deleted_at TIMESTAMPTZ,
+    UNIQUE(conversation_id, user_id)
+);
+CREATE INDEX IF NOT EXISTS ix_comm_reads_tenant_user ON comm_message_reads(tenant_id, user_id);
+
+CREATE TABLE IF NOT EXISTS comm_conversation_pins (
+    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    tenant_id UUID NOT NULL,
+    conversation_id UUID NOT NULL REFERENCES comm_conversations(id) ON DELETE CASCADE,
+    user_id UUID NOT NULL,
+    pinned_at TIMESTAMPTZ NOT NULL DEFAULT now(),
+    created_at TIMESTAMPTZ NOT NULL DEFAULT now(),
+    updated_at TIMESTAMPTZ NOT NULL DEFAULT now(),
+    deleted_at TIMESTAMPTZ,
+    UNIQUE(conversation_id, user_id)
+);
+CREATE INDEX IF NOT EXISTS ix_comm_pins_tenant_user ON comm_conversation_pins(tenant_id, user_id);
+
+CREATE TABLE IF NOT EXISTS comm_conversation_mutes (
+    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    tenant_id UUID NOT NULL,
+    conversation_id UUID NOT NULL REFERENCES comm_conversations(id) ON DELETE CASCADE,
+    user_id UUID NOT NULL,
+    muted_at TIMESTAMPTZ NOT NULL DEFAULT now(),
+    created_at TIMESTAMPTZ NOT NULL DEFAULT now(),
+    updated_at TIMESTAMPTZ NOT NULL DEFAULT now(),
+    deleted_at TIMESTAMPTZ,
+    UNIQUE(conversation_id, user_id)
+);
+CREATE INDEX IF NOT EXISTS ix_comm_mutes_tenant_user ON comm_conversation_mutes(tenant_id, user_id);
+
+CREATE TABLE IF NOT EXISTS comm_message_edits (
+    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    tenant_id UUID NOT NULL,
+    message_id UUID NOT NULL REFERENCES comm_messages(id) ON DELETE CASCADE,
+    old_content TEXT NOT NULL,
+    old_blocks JSONB NOT NULL DEFAULT '[]',
+    edited_by UUID NOT NULL,
+    edited_at TIMESTAMPTZ NOT NULL DEFAULT now(),
+    created_at TIMESTAMPTZ NOT NULL DEFAULT now(),
+    updated_at TIMESTAMPTZ NOT NULL DEFAULT now(),
+    deleted_at TIMESTAMPTZ
+);
+CREATE INDEX IF NOT EXISTS ix_comm_edits_tenant_msg ON comm_message_edits(tenant_id, message_id);

app/plugins/builtins/kommunikation/miniapp_registry.py

@@ -0,0 +1,73 @@
+"""Mini-App registry for plugin-provided interactive chat components."""
+
+from __future__ import annotations
+
+import logging
+from typing import Any, Callable, Awaitable
+
+from pydantic import BaseModel, Field
+
+logger = logging.getLogger(__name__)
+
+
+class MiniAppDef(BaseModel):
+    """Definition of a mini-app that plugins can register."""
+
+    app_id: str = Field(..., description="Unique app identifier")
+    name: str = Field(..., description="Display name")
+    icon: str = Field(default="app", description="Icon name")
+    description: str = Field(default="", description="App description")
+    plugin_name: str = Field(..., description="Plugin that registered this app")
+    render_schema: dict[str, Any] = Field(
+        default_factory=dict, description="JSON schema for frontend rendering"
+    )
+
+
+class MiniAppRegistry:
+    """Registry for mini-apps that plugins provide for chat embedding."""
+
+    def __init__(self) -> None:
+        self._apps: dict[str, MiniAppDef] = {}
+
+    def register(
+        self,
+        app_id: str,
+        name: str,
+        icon: str,
+        description: str,
+        plugin_name: str,
+        render_schema: dict[str, Any] | None = None,
+    ) -> None:
+        """Register a mini-app."""
+        app = MiniAppDef(
+            app_id=app_id,
+            name=name,
+            icon=icon,
+            description=description,
+            plugin_name=plugin_name,
+            render_schema=render_schema or {},
+        )
+        self._apps[app_id] = app
+        logger.info(f"Mini-app registered: {app_id} by {plugin_name}")
+
+    def unregister(self, app_id: str) -> None:
+        """Unregister a mini-app."""
+        app = self._apps.pop(app_id, None)
+        if app:
+            logger.info(f"Mini-app unregistered: {app_id}")
+
+    def unregister_plugin(self, plugin_name: str) -> None:
+        """Unregister all mini-apps from a specific plugin."""
+        to_remove = [app_id for app_id, app in self._apps.items() if app.plugin_name == plugin_name]
+        for app_id in to_remove:
+            self._apps.pop(app_id, None)
+        if to_remove:
+            logger.info(f"Unregistered {len(to_remove)} mini-apps from plugin {plugin_name}")
+
+    def list_apps(self) -> list[dict[str, Any]]:
+        """List all available mini-apps for frontend."""
+        return [app.model_dump() for app in self._apps.values()]
+
+    def get_app(self, app_id: str) -> MiniAppDef | None:
+        """Get a specific mini-app definition."""
+        return self._apps.get(app_id)

app/plugins/builtins/kommunikation/models.py

@@ -0,0 +1,283 @@
+"""SQLAlchemy models for the kommunikation plugin."""
+
+from __future__ import annotations
+
+import uuid
+from datetime import datetime
+from typing import Any
+
+from sqlalchemy import (
+    Boolean,
+    DateTime,
+    ForeignKey,
+    Index,
+    Integer,
+    String,
+    Text,
+    UniqueConstraint,
+    func,
+)
+from sqlalchemy.dialects.postgresql import JSONB, UUID as PGUUID
+from sqlalchemy.orm import Mapped, mapped_column
+
+from app.core.db import Base, TenantMixin
+
+
+class CommConversation(Base, TenantMixin):
+    """Conversation / Room — tenant-scoped, supports pinning, locking, archiving."""
+
+    __tablename__ = "comm_conversations"
+    __table_args__ = (
+        Index("ix_comm_conversations_tenant", "tenant_id"),
+        Index("ix_comm_conversations_tenant_pinned", "tenant_id", "is_pinned"),
+        Index("ix_comm_conversations_last_msg", "tenant_id", "last_msg_at"),
+    )
+
+    id: Mapped[uuid.UUID] = mapped_column(
+        PGUUID(as_uuid=True), primary_key=True, default=uuid.uuid4
+    )
+    title: Mapped[str | None] = mapped_column(String(255), nullable=True)
+    title_set_by: Mapped[uuid.UUID | None] = mapped_column(PGUUID(as_uuid=True), nullable=True)
+    is_pinned: Mapped[bool] = mapped_column(Boolean, nullable=False, default=False)
+    is_locked: Mapped[bool] = mapped_column(Boolean, nullable=False, default=False)
+    locked_by: Mapped[str | None] = mapped_column(String(100), nullable=True)
+    is_direct: Mapped[bool] = mapped_column(Boolean, nullable=False, default=False)
+    is_archived: Mapped[bool] = mapped_column(Boolean, nullable=False, default=False)
+    created_by: Mapped[uuid.UUID | None] = mapped_column(PGUUID(as_uuid=True), nullable=True)
+    created_by_type: Mapped[str] = mapped_column(String(20), nullable=False, default="user")
+    last_msg_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True), nullable=True)
+    last_msg_preview: Mapped[str | None] = mapped_column(Text, nullable=True)
+    last_msg_sender_type: Mapped[str | None] = mapped_column(String(50), nullable=True)
+    metadata_: Mapped[dict[str, Any]] = mapped_column("metadata", JSONB, default=dict, nullable=False)
+
+
+class CommParticipant(Base, TenantMixin):
+    """Participant in a conversation — user, ai, system, gateway, etc."""
+
+    __tablename__ = "comm_participants"
+    __table_args__ = (
+        UniqueConstraint(
+            "conversation_id", "participant_id", "participant_type",
+            name="uq_comm_participants_conv_part_type",
+        ),
+        Index("ix_comm_participants_tenant_conv", "tenant_id", "conversation_id"),
+        Index("ix_comm_participants_tenant_user", "tenant_id", "participant_id"),
+    )
+
+    id: Mapped[uuid.UUID] = mapped_column(
+        PGUUID(as_uuid=True), primary_key=True, default=uuid.uuid4
+    )
+    conversation_id: Mapped[uuid.UUID] = mapped_column(
+        PGUUID(as_uuid=True),
+        ForeignKey("comm_conversations.id", ondelete="CASCADE"),
+        nullable=False,
+        index=True,
+    )
+    participant_id: Mapped[uuid.UUID | None] = mapped_column(PGUUID(as_uuid=True), nullable=True)
+    participant_type: Mapped[str] = mapped_column(String(50), nullable=False)
+    display_name: Mapped[str | None] = mapped_column(String(255), nullable=True)
+    role: Mapped[str] = mapped_column(String(20), nullable=False, default="member")
+    joined_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), nullable=False, server_default=func.now())
+    left_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True), nullable=True)
+
+
+class CommMessage(Base, TenantMixin):
+    """Message in a conversation — text content plus rich content blocks."""
+
+    __tablename__ = "comm_messages"
+    __table_args__ = (
+        Index("ix_comm_messages_tenant_conv", "tenant_id", "conversation_id", "created_at"),
+        Index("ix_comm_messages_tenant_sender", "tenant_id", "sender_id"),
+    )
+
+    id: Mapped[uuid.UUID] = mapped_column(
+        PGUUID(as_uuid=True), primary_key=True, default=uuid.uuid4
+    )
+    conversation_id: Mapped[uuid.UUID] = mapped_column(
+        PGUUID(as_uuid=True),
+        ForeignKey("comm_conversations.id", ondelete="CASCADE"),
+        nullable=False,
+        index=True,
+    )
+    sender_id: Mapped[uuid.UUID | None] = mapped_column(PGUUID(as_uuid=True), nullable=True)
+    sender_type: Mapped[str] = mapped_column(String(50), nullable=False)
+    content: Mapped[str] = mapped_column(Text, nullable=False, default="")
+    content_format: Mapped[str] = mapped_column(String(20), nullable=False, default="text")
+    metadata_: Mapped[dict[str, Any]] = mapped_column("metadata", JSONB, default=dict, nullable=False)
+    reply_to_id: Mapped[uuid.UUID | None] = mapped_column(
+        PGUUID(as_uuid=True),
+        ForeignKey("comm_messages.id", ondelete="SET NULL"),
+        nullable=True,
+    )
+    is_pinned: Mapped[bool] = mapped_column(Boolean, nullable=False, default=False)
+    read_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True), nullable=True)
+    edited_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True), nullable=True)
+
+
+class CommMessageBlock(Base, TenantMixin):
+    """Rich content block attached to a message."""
+
+    __tablename__ = "comm_message_blocks"
+    __table_args__ = (
+        Index("ix_comm_blocks_tenant_msg", "tenant_id", "message_id"),
+    )
+
+    id: Mapped[uuid.UUID] = mapped_column(
+        PGUUID(as_uuid=True), primary_key=True, default=uuid.uuid4
+    )
+    message_id: Mapped[uuid.UUID] = mapped_column(
+        PGUUID(as_uuid=True),
+        ForeignKey("comm_messages.id", ondelete="CASCADE"),
+        nullable=False,
+        index=True,
+    )
+    block_type: Mapped[str] = mapped_column(String(50), nullable=False)
+    block_data: Mapped[dict[str, Any]] = mapped_column(JSONB, nullable=False)
+    sort_order: Mapped[int] = mapped_column(Integer, nullable=False, default=0)
+
+
+class CommMessageAttachment(Base, TenantMixin):
+    """File attachment on a message — DMS reference or comm-internal upload."""
+
+    __tablename__ = "comm_message_attachments"
+    __table_args__ = (
+        Index("ix_comm_attachments_tenant_msg", "tenant_id", "message_id"),
+    )
+
+    id: Mapped[uuid.UUID] = mapped_column(
+        PGUUID(as_uuid=True), primary_key=True, default=uuid.uuid4
+    )
+    message_id: Mapped[uuid.UUID] = mapped_column(
+        PGUUID(as_uuid=True),
+        ForeignKey("comm_messages.id", ondelete="CASCADE"),
+        nullable=False,
+        index=True,
+    )
+    file_id: Mapped[uuid.UUID | None] = mapped_column(PGUUID(as_uuid=True), nullable=True)
+    file_source: Mapped[str] = mapped_column(String(10), nullable=False, default="comm")
+    file_name: Mapped[str] = mapped_column(String(255), nullable=False)
+    file_type: Mapped[str] = mapped_column(String(255), nullable=False)
+    file_size: Mapped[int | None] = mapped_column(Integer, nullable=True)
+    thumbnail_path: Mapped[str | None] = mapped_column(String(1024), nullable=True)
+    metadata_: Mapped[dict[str, Any]] = mapped_column("metadata", JSONB, default=dict, nullable=False)
+
+
+class CommMessageReaction(Base, TenantMixin):
+    """Emoji reaction on a message."""
+
+    __tablename__ = "comm_message_reactions"
+    __table_args__ = (
+        UniqueConstraint("message_id", "user_id", "emoji", name="uq_comm_reactions_msg_user_emoji"),
+        Index("ix_comm_reactions_tenant_msg", "tenant_id", "message_id"),
+    )
+
+    id: Mapped[uuid.UUID] = mapped_column(
+        PGUUID(as_uuid=True), primary_key=True, default=uuid.uuid4
+    )
+    message_id: Mapped[uuid.UUID] = mapped_column(
+        PGUUID(as_uuid=True),
+        ForeignKey("comm_messages.id", ondelete="CASCADE"),
+        nullable=False,
+        index=True,
+    )
+    user_id: Mapped[uuid.UUID] = mapped_column(PGUUID(as_uuid=True), nullable=False)
+    emoji: Mapped[str] = mapped_column(String(50), nullable=False)
+
+
+class CommMessageRead(Base, TenantMixin):
+    """Read state per user per conversation."""
+
+    __tablename__ = "comm_message_reads"
+    __table_args__ = (
+        UniqueConstraint("conversation_id", "user_id", name="uq_comm_reads_conv_user"),
+        Index("ix_comm_reads_tenant_user", "tenant_id", "user_id"),
+    )
+
+    id: Mapped[uuid.UUID] = mapped_column(
+        PGUUID(as_uuid=True), primary_key=True, default=uuid.uuid4
+    )
+    conversation_id: Mapped[uuid.UUID] = mapped_column(
+        PGUUID(as_uuid=True),
+        ForeignKey("comm_conversations.id", ondelete="CASCADE"),
+        nullable=False,
+    )
+    user_id: Mapped[uuid.UUID] = mapped_column(PGUUID(as_uuid=True), nullable=False)
+    last_read_msg_id: Mapped[uuid.UUID | None] = mapped_column(
+        PGUUID(as_uuid=True),
+        ForeignKey("comm_messages.id", ondelete="SET NULL"),
+        nullable=True,
+    )
+    last_read_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True), nullable=False, server_default=func.now()
+    )
+
+
+class CommConversationPin(Base, TenantMixin):
+    """User-specific conversation pinning."""
+
+    __tablename__ = "comm_conversation_pins"
+    __table_args__ = (
+        UniqueConstraint("conversation_id", "user_id", name="uq_comm_pins_conv_user"),
+        Index("ix_comm_pins_tenant_user", "tenant_id", "user_id"),
+    )
+
+    id: Mapped[uuid.UUID] = mapped_column(
+        PGUUID(as_uuid=True), primary_key=True, default=uuid.uuid4
+    )
+    conversation_id: Mapped[uuid.UUID] = mapped_column(
+        PGUUID(as_uuid=True),
+        ForeignKey("comm_conversations.id", ondelete="CASCADE"),
+        nullable=False,
+    )
+    user_id: Mapped[uuid.UUID] = mapped_column(PGUUID(as_uuid=True), nullable=False)
+    pinned_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True), nullable=False, server_default=func.now()
+    )
+
+
+class CommConversationMute(Base, TenantMixin):
+    """User-specific conversation muting."""
+
+    __tablename__ = "comm_conversation_mutes"
+    __table_args__ = (
+        UniqueConstraint("conversation_id", "user_id", name="uq_comm_mutes_conv_user"),
+        Index("ix_comm_mutes_tenant_user", "tenant_id", "user_id"),
+    )
+
+    id: Mapped[uuid.UUID] = mapped_column(
+        PGUUID(as_uuid=True), primary_key=True, default=uuid.uuid4
+    )
+    conversation_id: Mapped[uuid.UUID] = mapped_column(
+        PGUUID(as_uuid=True),
+        ForeignKey("comm_conversations.id", ondelete="CASCADE"),
+        nullable=False,
+    )
+    user_id: Mapped[uuid.UUID] = mapped_column(PGUUID(as_uuid=True), nullable=False)
+    muted_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True), nullable=False, server_default=func.now()
+    )
+
+
+class CommMessageEdit(Base, TenantMixin):
+    """Edit history for messages — stores old content before each edit."""
+
+    __tablename__ = "comm_message_edits"
+    __table_args__ = (
+        Index("ix_comm_edits_tenant_msg", "tenant_id", "message_id"),
+    )
+
+    id: Mapped[uuid.UUID] = mapped_column(
+        PGUUID(as_uuid=True), primary_key=True, default=uuid.uuid4
+    )
+    message_id: Mapped[uuid.UUID] = mapped_column(
+        PGUUID(as_uuid=True),
+        ForeignKey("comm_messages.id", ondelete="CASCADE"),
+        nullable=False,
+        index=True,
+    )
+    old_content: Mapped[str] = mapped_column(Text, nullable=False)
+    old_blocks: Mapped[list[Any]] = mapped_column(JSONB, default=list, nullable=False)
+    edited_by: Mapped[uuid.UUID] = mapped_column(PGUUID(as_uuid=True), nullable=False)
+    edited_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True), nullable=False, server_default=func.now()
+    )

app/plugins/builtins/kommunikation/participant_registry.py

@@ -0,0 +1,89 @@
+"""Participant Registry — Andockpunkt für Plugins als Teilnehmer."""
+
+from __future__ import annotations
+
+import logging
+from abc import ABC, abstractmethod
+from typing import Any
+
+logger = logging.getLogger(__name__)
+
+
+class ParticipantHandler(ABC):
+    """Interface that plugins implement to act as a conversation participant."""
+
+    @abstractmethod
+    async def on_message_received(
+        self,
+        conversation_id: Any,
+        message: dict[str, Any],
+        conversation: dict[str, Any],
+        mentions: list[str],
+        context: dict[str, Any],
+    ) -> list[dict[str, Any]] | None:
+        """Called when a new message arrives in a conversation this participant is part of.
+
+        Args:
+            conversation_id: UUID of the conversation.
+            message: The new message dict.
+            conversation: Full conversation dict with participants.
+            mentions: Parsed @mention participant types.
+            context: Tenant, user, and other context.
+
+        Returns:
+            Optional list of new message dicts (e.g. AI response).
+            For passive readers (system) → return None.
+            For reactive participants (ai) → return [message_dict, ...].
+        """
+        pass
+
+    @abstractmethod
+    def get_participant_info(self) -> dict[str, Any]:
+        """Return metadata: display_name, avatar_url, capabilities, description."""
+        pass
+
+
+class ParticipantRegistry:
+    """Global registry for plugin participants."""
+
+    def __init__(self) -> None:
+        self._handlers: dict[str, ParticipantHandler] = {}
+
+    def register(self, participant_type: str, handler: ParticipantHandler) -> None:
+        """Register a plugin as a participant type."""
+        self._handlers[participant_type] = handler
+        logger.info(f"Participant registered: {participant_type}")
+
+    def unregister(self, participant_type: str) -> None:
+        """Unregister a participant type."""
+        handler = self._handlers.pop(participant_type, None)
+        if handler:
+            logger.info(f"Participant unregistered: {participant_type}")
+
+    def get_handler(self, participant_type: str) -> ParticipantHandler | None:
+        """Get the handler for a participant type."""
+        return self._handlers.get(participant_type)
+
+    def list_types(self) -> list[str]:
+        """List all registered participant types."""
+        return list(self._handlers.keys())
+
+    def get_all_info(self) -> dict[str, dict[str, Any]]:
+        """Get info for all registered participants."""
+        return {ptype: handler.get_participant_info() for ptype, handler in self._handlers.items()}
+
+
+# Global instance
+_registry = ParticipantRegistry()
+
+
+def get_participant_registry() -> ParticipantRegistry:
+    """Get the global participant registry."""
+    return _registry
+
+
+def reset_participant_registry_for_testing() -> ParticipantRegistry:
+    """Create a fresh registry for testing."""
+    global _registry
+    _registry = ParticipantRegistry()
+    return _registry

app/plugins/builtins/kommunikation/plugin.py

@@ -0,0 +1,91 @@
+"""Kommunikation plugin — unified messaging: chat, AI, system, messenger."""
+
+from __future__ import annotations
+
+import logging
+from typing import Any
+
+from app.plugins.base import BasePlugin
+from app.plugins.manifest import PluginManifest, PluginRouteDef
+
+logger = logging.getLogger(__name__)
+
+
+class KommunikationPlugin(BasePlugin):
+    """Unified messaging plugin: conversations, messages, participants, WebSocket, rich content."""
+
+    manifest = PluginManifest(
+        name="kommunikation",
+        version="1.0.0",
+        display_name="Kommunikation",
+        description=(
+            "Unified Messaging: Chat, KI, System, Messenger — "
+            "alles ist ein Teilnehmer."
+        ),
+        dependencies=["permissions", "dms"],
+        routes=[
+            PluginRouteDef(
+                path="/api/v1/comm",
+                module="app.plugins.builtins.kommunikation.routes",
+                router_attr="router",
+            ),
+        ],
+        events=[
+            "message.received",
+            "message.sent",
+            "conversation.created",
+            "conversation.updated",
+            "participant.joined",
+            "participant.left",
+            "reaction.added",
+        ],
+        migrations=["0001_initial.sql"],
+        permissions=[
+            "comm:read",
+            "comm:write",
+            "comm:create",
+            "comm:manage",
+            "comm:admin",
+            "comm:delete",
+        ],
+        is_core=True,
+    )
+
+    async def on_activate(self, db, service_container, event_bus) -> None:
+        """Register participant registry and WebSocket manager."""
+        await super().on_activate(db, service_container, event_bus)
+
+        # Register WebSocket manager as a shared service
+        from app.plugins.builtins.kommunikation.websocket_manager import WebSocketManager
+        ws_manager = WebSocketManager()
+        service_container.register("comm_websocket", ws_manager)
+
+        # Register Mini-App registry as a shared service
+        from app.plugins.builtins.kommunikation.miniapp_registry import MiniAppRegistry
+        miniapp_registry = MiniAppRegistry()
+        service_container.register("comm_miniapps", miniapp_registry)
+
+        logger.info("Kommunikation plugin activated — WebSocket + MiniApp registries ready")
+
+    async def on_deactivate(self, db, service_container, event_bus) -> None:
+        """Clean up registries."""
+        await super().on_deactivate(db, service_container, event_bus)
+        logger.info("Kommunikation plugin deactivated")
+
+    def get_notification_types(self) -> list[dict[str, Any]]:
+        return [
+            {
+                "type_key": "comm_message",
+                "category": "communication",
+                "label": "Neue Nachricht",
+                "description": "Neue Nachricht in einer Konversation",
+                "is_enabled_by_default": True,
+            },
+            {
+                "type_key": "comm_mention",
+                "category": "communication",
+                "label": "Erwähnung",
+                "description": "Du wurdest in einer Nachricht erwähnt",
+                "is_enabled_by_default": True,
+            },
+        ]

app/plugins/builtins/kommunikation/rbac.py

@@ -0,0 +1,136 @@
+"""Chat-internal RBAC logic — two-level permission checks."""
+
+from __future__ import annotations
+
+import logging
+import uuid
+from typing import Any
+
+from sqlalchemy import select
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from app.core.permissions import check_permission
+from app.plugins.builtins.kommunikation.models import CommParticipant
+
+logger = logging.getLogger(__name__)
+
+
+class CommRBAC:
+    """Chat-internal RBAC, integrated with the existing permission system."""
+
+    @staticmethod
+    async def get_user_role(
+        db: AsyncSession,
+        conversation_id: uuid.UUID,
+        user_id: uuid.UUID,
+    ) -> str | None:
+        """Get the user's role in a conversation, or None if not a participant."""
+        result = await db.execute(
+            select(CommParticipant).where(
+                CommParticipant.conversation_id == conversation_id,
+                CommParticipant.participant_id == user_id,
+                CommParticipant.participant_type == "user",
+                CommParticipant.left_at.is_(None),
+            )
+        )
+        participant = result.scalar_one_or_none()
+        return participant.role if participant else None
+
+    @staticmethod
+    async def is_participant(
+        db: AsyncSession,
+        conversation_id: uuid.UUID,
+        user_id: uuid.UUID,
+    ) -> bool:
+        """Check if a user is an active participant in a conversation."""
+        role = await CommRBAC.get_user_role(db, conversation_id, user_id)
+        return role is not None
+
+    @staticmethod
+    async def can_user_write(
+        db: AsyncSession,
+        conversation_id: uuid.UUID,
+        current_user: dict[str, Any],
+    ) -> bool:
+        """Check if user can write messages.
+
+        1. System permission 'comm:write' via check_permission
+        2. is_system_admin → always allowed
+        3. User must be participant with role 'admin' or 'member'
+        """
+        if current_user.get("is_system_admin"):
+            return True
+        if not check_permission(current_user, "comm:write"):
+            return False
+        user_id = uuid.UUID(current_user["user_id"])
+        role = await CommRBAC.get_user_role(db, conversation_id, user_id)
+        return role in ("admin", "member")
+
+    @staticmethod
+    async def can_user_manage(
+        db: AsyncSession,
+        conversation_id: uuid.UUID,
+        current_user: dict[str, Any],
+    ) -> bool:
+        """Check if user can manage participants.
+
+        1. System permission 'comm:manage' via check_permission
+        2. is_system_admin → always allowed
+        3. User must be conversation admin
+        """
+        if current_user.get("is_system_admin"):
+            return True
+        if not check_permission(current_user, "comm:manage"):
+            return False
+        user_id = uuid.UUID(current_user["user_id"])
+        role = await CommRBAC.get_user_role(db, conversation_id, user_id)
+        return role == "admin"
+
+    @staticmethod
+    async def can_user_delete(
+        db: AsyncSession,
+        conversation_id: uuid.UUID,
+        current_user: dict[str, Any],
+        is_own_message: bool = False,
+    ) -> bool:
+        """Check if user can delete messages or conversation.
+
+        1. is_system_admin → always allowed
+        2. For own messages: comm:write suffices
+        3. For others' messages: comm:delete + conversation admin
+        4. For conversation: comm:delete + admin role
+        """
+        if current_user.get("is_system_admin"):
+            return True
+        if is_own_message:
+            return check_permission(current_user, "comm:write")
+        if not check_permission(current_user, "comm:delete"):
+            return False
+        user_id = uuid.UUID(current_user["user_id"])
+        role = await CommRBAC.get_user_role(db, conversation_id, user_id)
+        return role == "admin"
+
+    @staticmethod
+    async def can_user_create(current_user: dict[str, Any]) -> bool:
+        """Check if user can create conversations."""
+        if current_user.get("is_system_admin"):
+            return True
+        return check_permission(current_user, "comm:create")
+
+    @staticmethod
+    async def can_user_change_role(
+        db: AsyncSession,
+        conversation_id: uuid.UUID,
+        current_user: dict[str, Any],
+    ) -> bool:
+        """Check if user can change participant roles.
+
+        Requires comm:admin permission + conversation admin role.
+        """
+        if current_user.get("is_system_admin"):
+            return True
+        if not check_permission(current_user, "comm:admin"):
+            return False
+        user_id = uuid.UUID(current_user["user_id"])
+        role = await CommRBAC.get_user_role(db, conversation_id, user_id)
+        return role == "admin"

app/plugins/builtins/kommunikation/routes.py

@@ -0,0 +1,532 @@
+"""REST API routes for the kommunikation plugin."""
+
+from __future__ import annotations
+
+import json
+import logging
+import uuid
+from typing import Any
+
+from fastapi import APIRouter, Depends, HTTPException, Query, UploadFile, File, WebSocket, WebSocketDisconnect, status
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from app.core.db import get_db
+from app.deps import get_current_user
+from app.plugins.builtins.kommunikation.rbac import CommRBAC
+from app.plugins.builtins.kommunikation.schemas import (
+    ConversationCreate,
+    ConversationUpdate,
+    MessageCreate,
+    MessageUpdate,
+    ParticipantAdd,
+    ParticipantRoleUpdate,
+    ReactionCreate,
+    ReadStateUpdate,
+    MiniAppStartRequest,
+)
+from app.plugins.builtins.kommunikation.services import (
+    add_participant,
+    add_reaction,
+    change_role,
+    create_conversation,
+    delete_message,
+    edit_message,
+    get_conversation,
+    get_messages,
+    list_conversations,
+    mark_read,
+    mute_conversation,
+    pin_conversation,
+    remove_participant,
+    remove_reaction,
+    send_message,
+    unmute_conversation,
+    unpin_conversation,
+    update_conversation,
+)
+from app.plugins.builtins.kommunikation.content_types import list_block_types
+from app.plugins.builtins.kommunikation.dms_bridge import DmsBridge
+
+logger = logging.getLogger(__name__)
+
+router = APIRouter(prefix="/api/v1/comm", tags=["kommunikation"])
+
+
+def _parse_uuid(val: str, field: str = "id") -> uuid.UUID:
+    try:
+        return uuid.UUID(val)
+    except (ValueError, TypeError):
+        raise HTTPException(400, detail={"detail": f"Invalid {field}", "code": "invalid_id"})
+
+
+# ─── Conversations ───
+
+@router.get("/conversations")
+async def list_user_conversations(
+    archived: bool = Query(False, description="Include archived conversations"),
+    current_user: dict = Depends(get_current_user),
+    db: AsyncSession = Depends(get_db),
+):
+    """List all conversations for the current user."""
+    tenant_id = uuid.UUID(current_user["tenant_id"])
+    user_id = uuid.UUID(current_user["user_id"])
+    convs = await list_conversations(db, tenant_id, user_id, include_archived=archived)
+    return {"items": convs, "total": len(convs)}
+
+
+@router.post("/conversations")
+async def create_new_conversation(
+    body: ConversationCreate,
+    current_user: dict = Depends(get_current_user),
+    db: AsyncSession = Depends(get_db),
+):
+    """Create a new conversation."""
+    if not await CommRBAC.can_user_create(current_user):
+        raise HTTPException(403, detail={"detail": "Permission denied", "code": "forbidden"})
+    tenant_id = uuid.UUID(current_user["tenant_id"])
+    user_id = uuid.UUID(current_user["user_id"])
+    return await create_conversation(
+        db, tenant_id, user_id,
+        title=body.title,
+        participant_ids=body.participant_ids,
+        is_direct=body.is_direct,
+        initial_message=body.initial_message,
+    )
+
+
+@router.get("/conversations/{conversation_id}")
+async def get_single_conversation(
+    conversation_id: str,
+    current_user: dict = Depends(get_current_user),
+    db: AsyncSession = Depends(get_db),
+):
+    """Get a single conversation with participants."""
+    tenant_id = uuid.UUID(current_user["tenant_id"])
+    user_id = uuid.UUID(current_user["user_id"])
+    conv_id = _parse_uuid(conversation_id, "conversation_id")
+    conv = await get_conversation(db, tenant_id, conv_id, user_id)
+    if conv is None:
+        raise HTTPException(404, detail={"detail": "Conversation not found", "code": "not_found"})
+    return conv
+
+
+@router.patch("/conversations/{conversation_id}")
+async def update_single_conversation(
+    conversation_id: str,
+    body: ConversationUpdate,
+    current_user: dict = Depends(get_current_user),
+    db: AsyncSession = Depends(get_db),
+):
+    """Update a conversation (title, archive)."""
+    tenant_id = uuid.UUID(current_user["tenant_id"])
+    user_id = uuid.UUID(current_user["user_id"])
+    conv_id = _parse_uuid(conversation_id, "conversation_id")
+    conv = await update_conversation(db, tenant_id, conv_id, user_id, title=body.title, is_archived=body.is_archived)
+    if conv is None:
+        raise HTTPException(404, detail={"detail": "Conversation not found", "code": "not_found"})
+    return conv
+
+
+@router.delete("/conversations/{conversation_id}")
+async def leave_or_delete_conversation(
+    conversation_id: str,
+    current_user: dict = Depends(get_current_user),
+    db: AsyncSession = Depends(get_db),
+):
+    """Leave (member) or delete (admin) a conversation."""
+    tenant_id = uuid.UUID(current_user["tenant_id"])
+    user_id = uuid.UUID(current_user["user_id"])
+    conv_id = _parse_uuid(conversation_id, "conversation_id")
+    # For now: just leave (set left_at)
+    success = await remove_participant(db, conv_id, user_id)
+    if not success:
+        raise HTTPException(404, detail={"detail": "Not a participant", "code": "not_found"})
+    return {"success": True}
+
+
+@router.post("/conversations/{conversation_id}/pin")
+async def pin_conv(
+    conversation_id: str,
+    current_user: dict = Depends(get_current_user),
+    db: AsyncSession = Depends(get_db),
+):
+    """Pin a conversation for the current user."""
+    tenant_id = uuid.UUID(current_user["tenant_id"])
+    user_id = uuid.UUID(current_user["user_id"])
+    conv_id = _parse_uuid(conversation_id, "conversation_id")
+    await pin_conversation(db, tenant_id, conv_id, user_id)
+    return {"success": True}
+
+
+@router.delete("/conversations/{conversation_id}/pin")
+async def unpin_conv(
+    conversation_id: str,
+    current_user: dict = Depends(get_current_user),
+    db: AsyncSession = Depends(get_db),
+):
+    """Unpin a conversation."""
+    user_id = uuid.UUID(current_user["user_id"])
+    conv_id = _parse_uuid(conversation_id, "conversation_id")
+    await unpin_conversation(db, conv_id, user_id)
+    return {"success": True}
+
+
+@router.post("/conversations/{conversation_id}/mute")
+async def mute_conv(
+    conversation_id: str,
+    current_user: dict = Depends(get_current_user),
+    db: AsyncSession = Depends(get_db),
+):
+    """Mute a conversation."""
+    tenant_id = uuid.UUID(current_user["tenant_id"])
+    user_id = uuid.UUID(current_user["user_id"])
+    conv_id = _parse_uuid(conversation_id, "conversation_id")
+    await mute_conversation(db, tenant_id, conv_id, user_id)
+    return {"success": True}
+
+
+@router.delete("/conversations/{conversation_id}/mute")
+async def unmute_conv(
+    conversation_id: str,
+    current_user: dict = Depends(get_current_user),
+    db: AsyncSession = Depends(get_db),
+):
+    """Unmute a conversation."""
+    user_id = uuid.UUID(current_user["user_id"])
+    conv_id = _parse_uuid(conversation_id, "conversation_id")
+    await unmute_conversation(db, conv_id, user_id)
+    return {"success": True}
+
+
+# ─── Participants ───
+
+@router.post("/conversations/{conversation_id}/participants")
+async def add_participant_endpoint(
+    conversation_id: str,
+    body: ParticipantAdd,
+    current_user: dict = Depends(get_current_user),
+    db: AsyncSession = Depends(get_db),
+):
+    """Add a participant to a conversation."""
+    tenant_id = uuid.UUID(current_user["tenant_id"])
+    conv_id = _parse_uuid(conversation_id, "conversation_id")
+    if not await CommRBAC.can_user_manage(db, conv_id, current_user):
+        raise HTTPException(403, detail={"detail": "Cannot manage participants", "code": "forbidden"})
+    result = await add_participant(db, tenant_id, conv_id, body.participant_id, body.participant_type, body.role)
+    if result is None:
+        raise HTTPException(400, detail={"detail": "Already a participant or invalid ID", "code": "bad_request"})
+    return result
+
+
+@router.delete("/conversations/{conversation_id}/participants/{participant_id}")
+async def remove_participant_endpoint(
+    conversation_id: str,
+    participant_id: str,
+    current_user: dict = Depends(get_current_user),
+    db: AsyncSession = Depends(get_db),
+):
+    """Remove a participant from a conversation."""
+    conv_id = _parse_uuid(conversation_id, "conversation_id")
+    pid = _parse_uuid(participant_id, "participant_id")
+    # Self-leave is always allowed
+    if pid != uuid.UUID(current_user["user_id"]):
+        if not await CommRBAC.can_user_manage(db, conv_id, current_user):
+            raise HTTPException(403, detail={"detail": "Cannot manage participants", "code": "forbidden"})
+    success = await remove_participant(db, conv_id, pid)
+    if not success:
+        raise HTTPException(404, detail={"detail": "Participant not found", "code": "not_found"})
+    return {"success": True}
+
+
+@router.patch("/conversations/{conversation_id}/participants/{participant_id}")
+async def change_participant_role(
+    conversation_id: str,
+    participant_id: str,
+    body: ParticipantRoleUpdate,
+    current_user: dict = Depends(get_current_user),
+    db: AsyncSession = Depends(get_db),
+):
+    """Change a participant's role."""
+    conv_id = _parse_uuid(conversation_id, "conversation_id")
+    pid = _parse_uuid(participant_id, "participant_id")
+    if not await CommRBAC.can_user_change_role(db, conv_id, current_user):
+        raise HTTPException(403, detail={"detail": "Cannot change roles", "code": "forbidden"})
+    result = await change_role(db, conv_id, pid, body.role)
+    if result is None:
+        raise HTTPException(404, detail={"detail": "Participant not found", "code": "not_found"})
+    return result
+
+
+# ─── Messages ───
+
+@router.get("/conversations/{conversation_id}/messages")
+async def get_conv_messages(
+    conversation_id: str,
+    page: int = Query(1, ge=1),
+    page_size: int = Query(50, ge=1, le=100),
+    before: str | None = Query(None),
+    current_user: dict = Depends(get_current_user),
+    db: AsyncSession = Depends(get_db),
+):
+    """Get paginated messages for a conversation."""
+    tenant_id = uuid.UUID(current_user["tenant_id"])
+    user_id = uuid.UUID(current_user["user_id"])
+    conv_id = _parse_uuid(conversation_id, "conversation_id")
+    if not await CommRBAC.is_participant(db, conv_id, user_id):
+        raise HTTPException(403, detail={"detail": "Not a participant", "code": "forbidden"})
+    before_id = _parse_uuid(before, "before") if before else None
+    return await get_messages(db, tenant_id, conv_id, page, page_size, before_id)
+
+
+@router.post("/conversations/{conversation_id}/messages")
+async def send_conv_message(
+    conversation_id: str,
+    body: MessageCreate,
+    current_user: dict = Depends(get_current_user),
+    db: AsyncSession = Depends(get_db),
+):
+    """Send a message to a conversation."""
+    tenant_id = uuid.UUID(current_user["tenant_id"])
+    user_id = uuid.UUID(current_user["user_id"])
+    conv_id = _parse_uuid(conversation_id, "conversation_id")
+    if not await CommRBAC.can_user_write(db, conv_id, current_user):
+        raise HTTPException(403, detail={"detail": "Cannot write to this conversation", "code": "forbidden"})
+    blocks_data = [b.model_dump() for b in body.blocks] if body.blocks else None
+    attachments_data = [a.model_dump() for a in body.attachments] if body.attachments else None
+    return await send_message(
+        db, tenant_id, conv_id, user_id, "user",
+        content=body.content,
+        content_format=body.content_format,
+        blocks=blocks_data,
+        reply_to_id=body.reply_to_id,
+        attachments=attachments_data,
+    )
+
+
+@router.patch("/messages/{message_id}")
+async def update_msg(
+    message_id: str,
+    body: MessageUpdate,
+    current_user: dict = Depends(get_current_user),
+    db: AsyncSession = Depends(get_db),
+):
+    """Edit a message or mark as read."""
+    tenant_id = uuid.UUID(current_user["tenant_id"])
+    user_id = uuid.UUID(current_user["user_id"])
+    msg_id = _parse_uuid(message_id, "message_id")
+    if body.content is not None:
+        result = await edit_message(db, tenant_id, msg_id, user_id, body.content)
+        if result is None:
+            raise HTTPException(404, detail={"detail": "Message not found", "code": "not_found"})
+        return result
+    return {"success": True}
+
+
+@router.delete("/messages/{message_id}")
+async def delete_msg(
+    message_id: str,
+    current_user: dict = Depends(get_current_user),
+    db: AsyncSession = Depends(get_db),
+):
+    """Delete a message."""
+    msg_id = _parse_uuid(message_id, "message_id")
+    success = await delete_message(db, msg_id)
+    if not success:
+        raise HTTPException(404, detail={"detail": "Message not found", "code": "not_found"})
+    return {"success": True}
+
+
+# ─── Attachments ───
+
+@router.post("/messages/{message_id}/attachments")
+async def upload_attachment(
+    message_id: str,
+    file: UploadFile = File(...),
+    current_user: dict = Depends(get_current_user),
+    db: AsyncSession = Depends(get_db),
+):
+    """Upload a file attachment to a message."""
+    tenant_id = uuid.UUID(current_user["tenant_id"])
+    user_id = uuid.UUID(current_user["user_id"])
+    msg_id = _parse_uuid(message_id, "message_id")
+    # Get conversation_id from message
+    from sqlalchemy import select
+    from app.plugins.builtins.kommunikation.models import CommMessage
+    result = await db.execute(select(CommMessage).where(CommMessage.id == msg_id))
+    msg = result.scalar_one_or_none()
+    if msg is None:
+        raise HTTPException(404, detail={"detail": "Message not found", "code": "not_found"})
+    try:
+        return await DmsBridge.store_attachment(db, tenant_id, msg.conversation_id, user_id, file)
+    except ValueError as e:
+        raise HTTPException(413, detail={"detail": str(e), "code": "file_too_large"})
+
+
+# ─── Reactions ───
+
+@router.post("/messages/{message_id}/reactions")
+async def add_msg_reaction(
+    message_id: str,
+    body: ReactionCreate,
+    current_user: dict = Depends(get_current_user),
+    db: AsyncSession = Depends(get_db),
+):
+    """Add an emoji reaction to a message."""
+    tenant_id = uuid.UUID(current_user["tenant_id"])
+    user_id = uuid.UUID(current_user["user_id"])
+    msg_id = _parse_uuid(message_id, "message_id")
+    result = await add_reaction(db, tenant_id, msg_id, user_id, body.emoji)
+    if result is None:
+        raise HTTPException(409, detail={"detail": "Already reacted", "code": "conflict"})
+    return result
+
+
+@router.delete("/messages/{message_id}/reactions/{emoji}")
+async def remove_msg_reaction(
+    message_id: str,
+    emoji: str,
+    current_user: dict = Depends(get_current_user),
+    db: AsyncSession = Depends(get_db),
+):
+    """Remove an emoji reaction."""
+    user_id = uuid.UUID(current_user["user_id"])
+    msg_id = _parse_uuid(message_id, "message_id")
+    success = await remove_reaction(db, msg_id, user_id, emoji)
+    if not success:
+        raise HTTPException(404, detail={"detail": "Reaction not found", "code": "not_found"})
+    return {"success": True}
+
+
+# ─── Read State ───
+
+@router.post("/conversations/{conversation_id}/read")
+async def mark_conv_read(
+    conversation_id: str,
+    body: ReadStateUpdate,
+    current_user: dict = Depends(get_current_user),
+    db: AsyncSession = Depends(get_db),
+):
+    """Mark a conversation as read."""
+    tenant_id = uuid.UUID(current_user["tenant_id"])
+    user_id = uuid.UUID(current_user["user_id"])
+    conv_id = _parse_uuid(conversation_id, "conversation_id")
+    await mark_read(db, tenant_id, conv_id, user_id, body.last_read_msg_id)
+    return {"success": True}
+
+
+# ─── Mini-Apps ───
+
+@router.get("/miniapps")
+async def list_miniapps(
+    current_user: dict = Depends(get_current_user),
+):
+    """List available mini-apps."""
+    from app.core.service_container import get_container
+    container = get_container()
+    if not container.has("comm_miniapps"):
+        return {"items": []}
+    registry = container.get("comm_miniapps")
+    return {"items": registry.list_apps()}
+
+
+@router.post("/conversations/{conversation_id}/miniapps")
+async def start_miniapp(
+    conversation_id: str,
+    body: MiniAppStartRequest,
+    current_user: dict = Depends(get_current_user),
+    db: AsyncSession = Depends(get_db),
+):
+    """Start a mini-app in a conversation."""
+    tenant_id = uuid.UUID(current_user["tenant_id"])
+    user_id = uuid.UUID(current_user["user_id"])
+    conv_id = _parse_uuid(conversation_id, "conversation_id")
+    if not await CommRBAC.can_user_write(db, conv_id, current_user):
+        raise HTTPException(403, detail={"detail": "Cannot write", "code": "forbidden"})
+    # Create a miniapp block as a message
+    return await send_message(
+        db, tenant_id, conv_id, user_id, "user",
+        content=f"[Mini-App: {body.app_id}]",
+        blocks=[{
+            "block_type": "miniapp",
+            "block_data": {"app_id": body.app_id, "config": body.config},
+        }],
+    )
+
+
+# ─── Content Types ───
+
+@router.get("/block-types")
+async def get_block_types():
+    """List all known content block types."""
+    return {"items": list_block_types()}
+
+
+# ─── WebSocket ───
+
+@router.websocket("/ws")
+async def websocket_endpoint(
+    websocket: WebSocket,
+):
+    """WebSocket endpoint for real-time messaging.
+
+    Authenticates via session cookie. On connect, subscribes user to all their conversations.
+    """
+    # Authenticate via session cookie
+    from app.config import get_settings
+    from app.core.auth import get_session_data, get_redis
+
+    settings = get_settings()
+    session_id = websocket.cookies.get(settings.session_cookie_name)
+    if not session_id:
+        await websocket.close(code=4001, reason="Not authenticated")
+        return
+
+    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
+
+    user_id = session_data["user_id"]
+    tenant_id = session_data["tenant_id"]
+
+    # 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()
+            msg = json.loads(data)
+            msg_type = msg.get("type")
+
+            if msg_type == "ping":
+                await ws_manager.send_to_user(user_id, {"type": "pong"})
+            elif msg_type == "subscribe":
+                conv_id = msg.get("conversation_id")
+                if conv_id:
+                    ws_manager.subscribe(conv_id, user_id)
+            elif msg_type == "unsubscribe":
+                conv_id = msg.get("conversation_id")
+                if conv_id:
+                    ws_manager.unsubscribe(conv_id, user_id)
+            elif msg_type == "typing":
+                conv_id = msg.get("conversation_id")
+                is_typing = msg.get("is_typing", False)
+                if conv_id:
+                    await ws_manager.send_to_conversation(
+                        conv_id,
+                        {"type": "typing", "conversation_id": conv_id, "user_id": user_id, "is_typing": is_typing},
+                        exclude_user=user_id,
+                    )
+    except WebSocketDisconnect:
+        await ws_manager.disconnect(websocket, user_id)
+    except Exception:
+        logger.exception("WebSocket error")
+        await ws_manager.disconnect(websocket, user_id)

app/plugins/builtins/kommunikation/schemas.py

@@ -0,0 +1,177 @@
+"""Pydantic schemas for the kommunikation plugin API."""
+
+from __future__ import annotations
+
+import uuid
+from datetime import datetime
+from typing import Any
+
+from pydantic import BaseModel, Field
+
+
+# ─── Conversation Schemas ───
+
+class ParticipantResponse(BaseModel):
+    id: str
+    conversation_id: str
+    participant_id: str | None = None
+    participant_type: str
+    display_name: str | None = None
+    role: str
+    joined_at: str | None = None
+
+
+class ConversationCreate(BaseModel):
+    title: str | None = None
+    participant_ids: list[str] = Field(default_factory=list)
+    participant_types: list[str] = Field(default_factory=lambda: ["user"])
+    initial_message: str | None = None
+    is_direct: bool = False
+
+
+class ConversationUpdate(BaseModel):
+    title: str | None = None
+    is_archived: bool | None = None
+
+
+class ConversationResponse(BaseModel):
+    id: str
+    title: str | None = None
+    is_locked: bool = False
+    locked_by: str | None = None
+    is_direct: bool = False
+    is_archived: bool = False
+    is_pinned: bool = False
+    created_by: str | None = None
+    created_by_type: str = "user"
+    last_msg_at: str | None = None
+    last_msg_preview: str | None = None
+    last_msg_sender_type: str | None = None
+    participants: list[ParticipantResponse] = Field(default_factory=list)
+    unread_count: int = 0
+    metadata: dict[str, Any] = Field(default_factory=dict)
+
+
+class ConversationListResponse(BaseModel):
+    items: list[ConversationResponse]
+    total: int
+
+
+# ─── Participant Management ───
+
+class ParticipantAdd(BaseModel):
+    participant_id: str
+    participant_type: str = "user"
+    role: str = "member"
+
+
+class ParticipantRoleUpdate(BaseModel):
+    role: str = Field(..., pattern="^(admin|member|reader)$")
+
+
+# ─── Message Schemas ───
+
+class MessageBlockCreate(BaseModel):
+    block_type: str
+    block_data: dict[str, Any]
+
+
+class MessageBlockResponse(BaseModel):
+    id: str
+    block_type: str
+    block_data: dict[str, Any]
+    sort_order: int = 0
+
+
+class AttachmentCreate(BaseModel):
+    file_id: str | None = None
+    file_source: str = "comm"
+
+
+class AttachmentResponse(BaseModel):
+    id: str
+    file_id: str | None = None
+    file_source: str = "comm"
+    file_name: str
+    file_type: str
+    file_size: int | None = None
+    thumbnail_path: str | None = None
+
+
+class MessageCreate(BaseModel):
+    content: str = ""
+    content_format: str = "text"
+    blocks: list[MessageBlockCreate] = Field(default_factory=list)
+    reply_to_id: str | None = None
+    attachments: list[AttachmentCreate] = Field(default_factory=list)
+
+
+class MessageUpdate(BaseModel):
+    content: str | None = None
+    read: bool | None = None
+
+
+class MessageResponse(BaseModel):
+    id: str
+    conversation_id: str
+    sender_id: str | None = None
+    sender_type: str
+    content: str = ""
+    content_format: str = "text"
+    metadata: dict[str, Any] = Field(default_factory=dict)
+    reply_to_id: str | None = None
+    is_pinned: bool = False
+    created_at: str | None = None
+    edited_at: str | None = None
+    blocks: list[MessageBlockResponse] = Field(default_factory=list)
+    attachments: list[AttachmentResponse] = Field(default_factory=list)
+    reactions: list[dict[str, Any]] = Field(default_factory=list)
+
+
+class MessageListResponse(BaseModel):
+    items: list[MessageResponse]
+    total: int
+    page: int = 1
+    has_more: bool = False
+
+
+# ─── Reaction Schemas ───
+
+class ReactionCreate(BaseModel):
+    emoji: str
+
+
+class ReactionResponse(BaseModel):
+    id: str
+    message_id: str
+    user_id: str
+    emoji: str
+
+
+# ─── Read State ───
+
+class ReadStateUpdate(BaseModel):
+    last_read_msg_id: str | None = None
+
+
+# ─── Mini-App Schemas ───
+
+class MiniAppResponse(BaseModel):
+    app_id: str
+    name: str
+    icon: str
+    description: str
+    plugin_name: str
+    render_schema: dict[str, Any] = Field(default_factory=dict)
+
+
+class MiniAppStartRequest(BaseModel):
+    app_id: str
+    config: dict[str, Any] = Field(default_factory=dict)
+
+
+# ─── WebSocket Message Schemas ───
+
+class WSMessage(BaseModel):
+    type: str
+    data: dict[str, Any] = Field(default_factory=dict)

app/plugins/builtins/kommunikation/search_provider.py

@@ -0,0 +1,112 @@
+"""Search provider for unified_search integration."""
+
+from __future__ import annotations
+
+import logging
+import uuid
+from typing import Any
+
+from sqlalchemy import select, func, or_
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from app.plugins.builtins.kommunikation.models import (
+    CommConversation,
+    CommMessage,
+    CommParticipant,
+)
+
+logger = logging.getLogger(__name__)
+
+
+class CommSearchProvider:
+    """Provider for unified_search — searches conversations and messages."""
+
+    async def search(
+        self,
+        db: AsyncSession,
+        tenant_id: uuid.UUID,
+        user_id: uuid.UUID,
+        query: str,
+        limit: int = 20,
+    ) -> list[dict[str, Any]]:
+        """Search in messages and conversations the user has access to."""
+        results: list[dict[str, Any]] = []
+
+        # Get user's conversation IDs
+        conv_result = await db.execute(
+            select(CommParticipant.conversation_id).where(
+                CommParticipant.participant_id == user_id,
+                CommParticipant.participant_type == "user",
+                CommParticipant.left_at.is_(None),
+                CommParticipant.tenant_id == tenant_id,
+            )
+        )
+        conv_ids = [row[0] for row in conv_result.fetchall()]
+
+        if not conv_ids:
+            return results
+
+        # Search in messages
+        msg_result = await db.execute(
+            select(CommMessage, CommConversation.title)
+            .join(CommConversation, CommConversation.id == CommMessage.conversation_id)
+            .where(
+                CommMessage.conversation_id.in_(conv_ids),
+                CommMessage.tenant_id == tenant_id,
+                CommMessage.deleted_at.is_(None),
+                CommMessage.content.ilike(f"%{query}%"),
+            )
+            .order_by(CommMessage.created_at.desc())
+            .limit(limit)
+        )
+
+        for msg, conv_title in msg_result.fetchall():
+            # Build snippet around match
+            content = msg.content or ""
+            idx = content.lower().find(query.lower())
+            if idx >= 0:
+                start = max(0, idx - 30)
+                end = min(len(content), idx + len(query) + 30)
+                snippet = ("..." if start > 0 else "") + content[start:end] + ("..." if end < len(content) else "")
+            else:
+                snippet = content[:100]
+
+            results.append({
+                "type": "message",
+                "id": str(msg.id),
+                "conversation_id": str(msg.conversation_id),
+                "conversation_title": conv_title,
+                "content": msg.content,
+                "sender_type": msg.sender_type,
+                "created_at": msg.created_at.isoformat() if msg.created_at else None,
+                "snippet": snippet,
+            })
+
+        # Search in conversation titles
+        conv_title_result = await db.execute(
+            select(CommConversation).where(
+                CommConversation.id.in_(conv_ids),
+                CommConversation.tenant_id == tenant_id,
+                CommConversation.deleted_at.is_(None),
+                CommConversation.title.ilike(f"%{query}%"),
+            )
+            .limit(limit)
+        )
+
+        for conv in conv_title_result.scalars().all():
+            results.append({
+                "type": "conversation",
+                "id": str(conv.id),
+                "title": conv.title,
+                "last_msg_at": conv.last_msg_at.isoformat() if conv.last_msg_at else None,
+            })
+
+        return results
+
+    async def index_message(self, message: dict[str, Any]) -> None:
+        """Index a message for search (placeholder for future full-text indexing)."""
+        pass
+
+    async def reindex_all(self, db: AsyncSession, tenant_id: uuid.UUID) -> None:
+        """Full reindex (placeholder for future full-text indexing)."""
+        pass

app/plugins/builtins/kommunikation/websocket_manager.py

@@ -0,0 +1,89 @@
+"""WebSocket connection manager for the kommunikation plugin."""
+
+from __future__ import annotations
+
+import json
+import logging
+from typing import Any
+
+from fastapi import WebSocket
+
+logger = logging.getLogger(__name__)
+
+
+class WebSocketManager:
+    """Manages WebSocket connections per user for real-time messaging."""
+
+    def __init__(self) -> None:
+        # user_id (str) → list of WebSocket connections
+        self._connections: dict[str, list[WebSocket]] = {}
+        # conversation_id (str) → set of user_ids subscribed
+        self._subscriptions: dict[str, set[str]] = {}
+
+    async def connect(self, websocket: WebSocket, user_id: str) -> None:
+        """Accept and register a new WebSocket connection."""
+        await websocket.accept()
+        if user_id not in self._connections:
+            self._connections[user_id] = []
+        self._connections[user_id].append(websocket)
+        logger.debug(f"WebSocket connected: user={user_id}, total={len(self._connections[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)
+            # Remove from all subscriptions
+            for conv_id, users in self._subscriptions.items():
+                users.discard(user_id)
+        logger.debug(f"WebSocket disconnected: user={user_id}, remaining={len(conns)}")
+
+    def subscribe(self, conversation_id: str, user_id: str) -> None:
+        """Subscribe a user to a conversation's updates."""
+        if conversation_id not in self._subscriptions:
+            self._subscriptions[conversation_id] = set()
+        self._subscriptions[conversation_id].add(user_id)
+
+    def unsubscribe(self, conversation_id: str, user_id: str) -> None:
+        """Unsubscribe a user from a conversation."""
+        if conversation_id in self._subscriptions:
+            self._subscriptions[conversation_id].discard(user_id)
+
+    async def send_to_user(self, user_id: str, message: dict[str, Any]) -> None:
+        """Send a message to all connections of a specific user."""
+        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 send to user {user_id}, removing connection")
+                await self.disconnect(ws, user_id)
+
+    async def send_to_conversation(
+        self,
+        conversation_id: str,
+        message: dict[str, Any],
+        exclude_user: str | None = None,
+    ) -> None:
+        """Send a message to all users subscribed to a conversation."""
+        user_ids = self._subscriptions.get(conversation_id, set())
+        for user_id in list(user_ids):
+            if exclude_user and user_id == exclude_user:
+                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)
+
+    def get_online_users(self) -> list[str]:
+        """Get list of currently connected user IDs."""
+        return list(self._connections.keys())
+
+    def is_user_online(self, user_id: str) -> bool:
+        """Check if a user has any active connections."""
+        return user_id in self._connections and len(self._connections[user_id]) > 0

app/plugins/builtins/system_notif/participant_handler.py

@@ -0,0 +1,46 @@
+"""System participant handler — passive participant that only reads."""
+
+from __future__ import annotations
+
+import logging
+from typing import Any
+
+from app.plugins.builtins.kommunikation.participant_registry import ParticipantHandler
+
+logger = logging.getLogger(__name__)
+
+
+class SystemParticipantHandler(ParticipantHandler):
+    """System participant — passive, does not respond to messages.
+
+    The system participant only sends messages triggered by system events
+    (handled in the plugin's event handlers). It does not respond to
+    user messages in the chat.
+    """
+
+    def __init__(self, container: Any) -> None:
+        self._container = container
+
+    async def on_message_received(
+        self,
+        conversation_id: Any,
+        message: dict[str, Any],
+        conversation: dict[str, Any],
+        mentions: list[str],
+        context: dict[str, Any],
+    ) -> list[dict[str, Any]] | None:
+        """System is passive — does not respond to messages.
+
+        Users can interact with action_card buttons (open, archive) which
+        are handled via the frontend, not via new messages.
+        """
+        return None
+
+    def get_participant_info(self) -> dict[str, Any]:
+        """Return participant metadata."""
+        return {
+            "display_name": "System",
+            "avatar_url": None,
+            "capabilities": ["notifications", "action_cards"],
+            "description": "System-Benachrichtigungen",
+        }

app/plugins/builtins/system_notif/plugin.py

@@ -0,0 +1,223 @@
+"""System Notification plugin — converts system events into chat messages."""
+
+from __future__ import annotations
+
+import logging
+from typing import Any
+
+from app.plugins.base import BasePlugin
+from app.plugins.manifest import PluginManifest
+
+logger = logging.getLogger(__name__)
+
+
+class SystemNotifPlugin(BasePlugin):
+    """System notifications as a participant in the kommunikation plugin."""
+
+    manifest = PluginManifest(
+        name="system_notif",
+        version="1.0.0",
+        display_name="System Benachrichtigungen",
+        description=(
+            "Wandelt System-Events in Chat-Nachrichten um. "
+            "Registriert sich als 'system' Teilnehmer am kommunikation Plugin."
+        ),
+        dependencies=["kommunikation"],
+        routes=[],
+        events=[
+            "lead.created",
+            "contact.created",
+            "contact.updated",
+            "task.overdue",
+            "task.created",
+            "mail.received",
+            "user.created",
+            "workflow.completed",
+            "notification.created",
+        ],
+        migrations=[],
+        permissions=["system_notif:read"],
+        is_core=False,
+    )
+
+    def __init__(self) -> None:
+        super().__init__()
+        self._system_handler = None
+
+    async def on_activate(self, db, service_container, event_bus) -> None:
+        """Register as system participant and subscribe to events."""
+        await super().on_activate(db, service_container, event_bus)
+
+        from app.plugins.builtins.system_notif.participant_handler import SystemParticipantHandler
+        from app.plugins.builtins.kommunikation.participant_registry import get_participant_registry
+
+        self._system_handler = SystemParticipantHandler(service_container)
+        registry = get_participant_registry()
+        registry.register("system", self._system_handler)
+
+        logger.info("System notification plugin activated — registered as 'system' participant")
+
+    async def on_deactivate(self, db, service_container, event_bus) -> None:
+        """Unregister participant."""
+        from app.plugins.builtins.kommunikation.participant_registry import get_participant_registry
+
+        get_participant_registry().unregister("system")
+        self._system_handler = None
+        await super().on_deactivate(db, service_container, event_bus)
+        logger.info("System notification plugin deactivated")
+
+    # ─── Event Handlers ───
+
+    async def on_lead_created(self, payload: dict[str, Any]) -> None:
+        """Handle lead.created event → system message."""
+        await self._create_system_notification(payload, event_type="lead.created")
+
+    async def on_contact_created(self, payload: dict[str, Any]) -> None:
+        """Handle contact.created event → system message."""
+        await self._create_system_notification(payload, event_type="contact.created")
+
+    async def on_contact_updated(self, payload: dict[str, Any]) -> None:
+        """Handle contact.updated event → system message."""
+        await self._create_system_notification(payload, event_type="contact.updated")
+
+    async def on_task_overdue(self, payload: dict[str, Any]) -> None:
+        """Handle task.overdue event → system message (warning)."""
+        await self._create_system_notification(payload, event_type="task.overdue", severity="warning")
+
+    async def on_task_created(self, payload: dict[str, Any]) -> None:
+        """Handle task.created event → system message."""
+        await self._create_system_notification(payload, event_type="task.created")
+
+    async def on_mail_received(self, payload: dict[str, Any]) -> None:
+        """Handle mail.received event → system message."""
+        await self._create_system_notification(payload, event_type="mail.received")
+
+    async def on_user_created(self, payload: dict[str, Any]) -> None:
+        """Handle user.created event → system message."""
+        await self._create_system_notification(payload, event_type="user.created")
+
+    async def on_workflow_completed(self, payload: dict[str, Any]) -> None:
+        """Handle workflow.completed event → system message."""
+        await self._create_system_notification(payload, event_type="workflow.completed")
+
+    async def on_notification_created(self, payload: dict[str, Any]) -> None:
+        """Handle notification.created event → system message.
+
+        This is the bridge from the core notification system to the kommunikation plugin.
+        Core code publishes 'notification.created' on the EventBus, this plugin
+        converts it into a comm_message in the user's System room.
+        """
+        await self._create_system_notification(payload, event_type="notification.created")
+
+    async def _create_system_notification(
+        self,
+        payload: dict[str, Any],
+        event_type: str,
+        severity: str = "info",
+    ) -> None:
+        """Create a system notification message in the user's System room."""
+        import uuid
+
+        from app.core.db import create_db_session
+        from app.plugins.builtins.kommunikation.services import create_plugin_room, send_message
+
+        tenant_id_str = payload.get("tenant_id")
+        user_id_str = payload.get("user_id")
+
+        if not tenant_id_str or not user_id_str:
+            logger.warning("System notification missing tenant_id or user_id in payload: %s", payload)
+            return
+
+        try:
+            tenant_id = uuid.UUID(tenant_id_str)
+            user_id = uuid.UUID(user_id_str)
+        except (ValueError, TypeError):
+            logger.warning("System notification invalid UUIDs: tenant=%s user=%s", tenant_id_str, user_id_str)
+            return
+
+        # Build notification content from payload
+        title = payload.get("title", "")
+        body = payload.get("body", "")
+        action_url = payload.get("action_url", "")
+
+        if not title:
+            # Generate title from event type
+            event_titles = {
+                "lead.created": "Neuer Lead",
+                "contact.created": "Neuer Kontakt",
+                "contact.updated": "Kontakt aktualisiert",
+                "task.overdue": "Aufgabe überfällig",
+                "task.created": "Neue Aufgabe",
+                "mail.received": "Neue E-Mail",
+                "user.created": "Neuer Benutzer",
+                "workflow.completed": "Workflow abgeschlossen",
+                "notification.created": "Benachrichtigung",
+            }
+            title = event_titles.get(event_type, event_type)
+
+        content = f"**{title}**"
+        if body:
+            content += f"\n{body}"
+
+        # Build action_card block if action_url is present
+        blocks = []
+        if action_url:
+            blocks.append({
+                "block_type": "action_card",
+                "block_data": {
+                    "title": title,
+                    "body": body or "",
+                    "actions": [
+                        {"label": "Öffnen", "action": action_url, "type": "primary"},
+                        {"label": "Archivieren", "action": "dismiss", "type": "secondary"},
+                    ],
+                },
+            })
+
+        async with create_db_session(tenant_id) as db:
+            # Ensure System room exists for this user
+            await create_plugin_room(
+                db, tenant_id, user_id,
+                plugin_name="system_notif",
+                title="System",
+                participant_type="system",
+                user_role="reader",
+            )
+
+            # Find the System room conversation
+            from sqlalchemy import select
+            from app.plugins.builtins.kommunikation.models import CommConversation, CommParticipant
+
+            result = await db.execute(
+                select(CommConversation).where(
+                    CommConversation.tenant_id == tenant_id,
+                    CommConversation.title == "System",
+                    CommConversation.is_locked == True,
+                    CommConversation.locked_by == "system_notif",
+                    CommConversation.deleted_at.is_(None),
+                ).join(CommParticipant, CommParticipant.conversation_id == CommConversation.id).where(
+                    CommParticipant.participant_id == user_id,
+                    CommParticipant.participant_type == "user",
+                    CommParticipant.left_at.is_(None),
+                )
+            )
+            conv = result.scalar_one_or_none()
+            if conv is None:
+                logger.warning("Could not find System room for user %s", user_id)
+                return
+
+            # Send the system message
+            await send_message(
+                db, tenant_id, conv.id,
+                sender_id=None,
+                sender_type="system",
+                content=content,
+                content_format="markdown",
+                blocks=blocks if blocks else None,
+                metadata={"event_type": event_type, "severity": severity},
+            )
+
+            logger.info("System notification created: %s for user %s", event_type, user_id)
+
+    def get_notification_types(self) -> list[dict[str, Any]]:
+        return []

docs/konzept-unified-messaging.md

@@ -0,0 +1,624 @@
+# Konzept: Unified Messaging System für LeoCRM
+
+## Vision
+
+Alle Kommunikation in LeoCRM — KI-Chat, Mitarbeiter-Chat, System-Benachrichtigungen, externe Messenger — läuft über **ein einheitliches Messaging-System**, das als Plugin-Architektur realisiert wird.
+
+**Kernprinzip:** Alles ist ein Teilnehmer. Die KI ist ein Teilnehmer. Das System ist ein Teilnehmer. Ein WhatsApp-Gateway ist ein Teilnehmer. Es gibt keine Sonderbehandlung.
+
+---
+
+## Plugin-Architektur
+
+### Übersicht: Drei Plugin-Ebenen
+
+```
+┌─────────────────────────────────────────────────────────────┐
+│                    Frontend (MessageSidebar)                 │
+│         Ein Feed, eine Konversations-Liste, ein Eingabefeld   │
+└──────────────────────────┬──────────────────────────────────┘
+│                           │ WebSocket                         │
+┌──────────────────────────┴──────────────────────────────────┐
+│              Plugin: kommunikation (Core)                     │
+│  ┌─────────────┐  ┌──────────────┐  ┌────────────────────┐  │
+│  │ conversations│  │  messages    │  │  participants      │  │
+│  │  + Räume     │  │  + Rich Cont.│  │  + Registrierung   │  │
+│  └─────────────┘  └──────────────┘  └────────────────────┘  │
+│  ┌──────────────────────────────────────────────────────┐   │
+│  │           Participant Registry (Hook)                │   │
+│  │  Andockpunkt für: ai_assistant, system_notif,         │   │
+│  │  whatsapp_gateway, telegram_gateway, ...              │   │
+│  └──────────────────────────────────────────────────────┘   │
+└──────────────────────────┬──────────────────────────────────┘
+│                           │ EventBus                          │
+┌──────────────────────────┴──────────────────────────────────┐
+│  Plugin: ai_assistant    │  Plugin: system_notif  │  Plugin:   │
+│  dockt als Teilnehmer an  │  dockt als Teilnehmer │  whatsapp │
+│  @KI → AI-Response        │  Events → Messages    │  Gateway  │
+└─────────────────────────────────────────────────────────────┘
+```
+
+### 1. Plugin `kommunikation` (Core-Plugin)
+
+**Verantwortung:** Chat-Infrastruktur — Konversationen, Nachrichten, Teilnehmer-Verwaltung, WebSocket, Rich Content Transport.
+
+**Basiert auf:** AI Assistant Plugin (Sessions/Messages/Streaming) als Grundlage, erweitert um Multi-Teilnehmer und Rich Content.
+
+**Manifest:**
+```python
+PluginManifest(
+    name="kommunikation",
+    version="1.0.0",
+    display_name="Kommunikation",
+    description="Unified Messaging: Chat, KI, System, Messenger",
+    dependencies=[],
+    routes=[
+        PluginRouteDef(path="/api/v1/comm", module="...routes", router_attr="router"),
+    ],
+    events=["message.received", "conversation.created", "participant.joined"],
+    migrations=["0001_initial.sql"],
+    permissions=["comm:read", "comm:write", "comm:manage"],
+    is_core=True,
+)
+```
+
+**Komponenten:**
+- `models.py` — Conversation, Message, Participant, MessageAttachment, MessageReaction
+- `schemas.py` — Pydantic-Schemas für API
+- `routes.py` — REST-API + WebSocket
+- `services.py` — Business Logic (Nachrichten senden, Konversationen verwalten)
+- `participant_registry.py` — Registrierungs-Interface für andere Plugins
+- `content_types.py` — Rich Content Type-Definitionen
+- `websocket_manager.py` — WebSocket-Verbindungs-Manager
+
+### 2. Participant Registry (Andockpunkt)
+
+Das `kommunikation` Plugin stellt eine **Participant Registry** bereit — ein Interface, über das sich andere Plugins als Teilnehmer registrieren.
+
+```python
+# In kommunikation/participant_registry.py
+
+class ParticipantType(Enum):
+    USER = "user"
+    AI = "ai"
+    SYSTEM = "system"
+    WHATSAPP = "whatsapp"
+    TELEGRAM = "telegram"
+    EMAIL = "email"
+    SLACK = "slack"
+    # Erweiterbar...
+
+class ParticipantHandler(ABC):
+    """Interface das Plugins implementieren um als Teilnehmer zu fungieren."""
+    
+    @abstractmethod
+    async def on_message_received(self, conversation_id, message, context) -> Message | None:
+        """Wird aufgerufen wenn eine neue Nachricht in einer Konversation
+        ankommt, an der dieser Teilnehmer beteiligt ist.
+        
+        Rückgabe: Optional eine neue Message (z.B. AI-Response).
+        Für reine Leser (system) → return None.
+        Für reaktive Teilnehmer (ai) → return Message(...).
+        """
+        pass
+    
+    @abstractmethod
+    def get_participant_info(self) -> dict:
+        """Metadaten: name, avatar_url, display_name, capabilities."""
+        pass
+
+class ParticipantRegistry:
+    """Global registry für Plugin-Teilnehmer."""
+    
+    def register(self, participant_type: str, handler: ParticipantHandler) -> None:
+        """Plugin registriert sich als Teilnehmer-Typ."""
+        
+    def get_handler(self, participant_type: str) -> ParticipantHandler | None:
+        """Handler für einen Teilnehmer-Typ abrufen."""
+```
+
+**Wie Plugins andocken:**
+
+```python
+# In ai_assistant/plugin.py on_activate():
+from app.plugins.builtins.kommunikation.participant_registry import get_registry
+
+class AIAssistantPlugin(BasePlugin):
+    async def on_activate(self, db, container, event_bus):
+        await super().on_activate(db, container, event_bus)
+        # Als AI-Teilnehmer registrieren
+        registry = get_registry()
+        registry.register("ai", AIParticipantHandler(self.services))
+```
+
+```python
+# In system_notif/plugin.py on_activate():
+class SystemNotificationPlugin(BasePlugin):
+    async def on_activate(self, db, container, event_bus):
+        await super().on_activate(db, container, event_bus)
+        # Als System-Teilnehmer registrieren
+        registry = get_registry()
+        registry.register("system", SystemParticipantHandler(...))
+        # Auf Events hören und Nachrichten erzeugen
+        event_bus.subscribe("lead.created", self.on_lead_created)
+```
+
+### 3. Plugin `ai_assistant` (Anpassung)
+
+Das bestehende AI Assistant Plugin wird angepasst:
+- Behält: Provider-Verwaltung, Modelle, Agents, Tools, Streaming
+- Neu: Implementiert `ParticipantHandler` und registriert sich bei `kommunikation`
+- Neu: Lauscht auf `message.received` Events → wenn `@KI` erwähnt wird oder Konversation AI als Teilnehmer hat → generiert Response
+- Alt: Eigene `AIChatSession` / `AIChatMessage` Tabellen bleiben für Abwärtskompatibilität, werden langfristig migriert
+- Neu: Schreibt Nachrichten in `kommunikation.messages` statt nur in eigene Tabellen
+
+### 4. Plugin `system_notif` (Neu)
+
+**Verantwortung:** System-Events in Nachrichten umwandeln.
+
+- Registriert sich als `system` Teilnehmer
+- Hört auf EventBus-Events (`lead.created`, `contact.created`, `task.overdue`, ...)
+- Erzeugt Nachrichten in der System-Konversation des Users
+- Notifications haben `metadata.action_url` und `metadata.severity`
+- Bestehende Notification-Tabelle wird migriert
+
+### 5. Messenger-Gateway Plugins (Später)
+
+Jeder Messenger ist ein eigenes Plugin:
+- `whatsapp_gateway` — registriert sich als `whatsapp` Teilnehmer
+- `telegram_gateway` — registriert sich als `telegram` Teilnehmer
+- `email_gateway` — registriert sich als `email` Teilnehmer
+
+Jedes implementiert `ParticipantHandler` und ggf. Webhook-Routes.
+
+---
+
+## Datenmodell
+
+### Tabelle `comm_conversations`
+```
+id            UUID PK
+tenant_id     UUID NOT NULL
+title         TEXT NULL          -- benannte Räume
+title_set_by  UUID NULL          -- user_id der den Titel gesetzt hat
+is_pinned     BOOLEAN DEFAULT FALSE
+is_direct     BOOLEAN DEFAULT FALSE  -- 1:1 vs Gruppe
+created_by    UUID NULL
+last_msg_at   TIMESTAMP
+last_msg_preview  TEXT NULL      -- für Konversations-Liste
+last_msg_sender_type  TEXT NULL   -- für Icon in Liste
+metadata      JSONB DEFAULT '{}'  -- z.B. {"pinned_by": "user_id"}
+created_at    TIMESTAMP DEFAULT NOW()
+updated_at    TIMESTAMP DEFAULT NOW()
+```
+
+### Tabelle `comm_participants`
+```
+id                UUID PK
+conversation_id    UUID FK → comm_conversations
+participant_id     UUID NULL       -- user_id (NULL für ai/system/gateways)
+participant_type   TEXT NOT NULL   -- 'user', 'ai', 'system', 'whatsapp', ...
+display_name       TEXT NULL       -- override (z.B. WhatsApp-Kontakt-Name)
+joined_at          TIMESTAMP DEFAULT NOW()
+left_at            TIMESTAMP NULL
+```
+
+### Tabelle `comm_messages`
+```
+id              UUID PK
+tenant_id       UUID NOT NULL
+conversation_id  UUID FK → comm_conversations
+sender_id       UUID NULL       -- user_id (NULL für ai/system/gateways)
+sender_type     TEXT NOT NULL   -- 'user', 'ai', 'system', 'whatsapp', ...
+content         TEXT NOT NULL   -- Text-Inhalt (Markdown)
+content_format  TEXT DEFAULT 'text'  -- 'text', 'markdown', 'html'
+metadata        JSONB DEFAULT '{}'  -- typ-spezifische Daten
+reply_to_id     UUID NULL FK → comm_messages  -- Thread-Antwort
+created_at      TIMESTAMP DEFAULT NOW()
+read_at         TIMESTAMP NULL
+edited_at       TIMESTAMP NULL
+deleted_at      TIMESTAMP NULL
+```
+
+### Tabelle `comm_message_attachments`
+```
+id           UUID PK
+message_id   UUID FK → comm_messages
+file_name    TEXT NOT NULL
+file_path    TEXT NOT NULL     -- Pfad im DMS oder S3
+file_type    TEXT NOT NULL    -- MIME type
+file_size    BIGINT
+thumbnail_path TEXT NULL      -- für Bilder/Videos
+metadata     JSONB DEFAULT '{}'  -- z.B. {"width": 1920, "height": 1080}
+created_at   TIMESTAMP DEFAULT NOW()
+```
+
+### Tabelle `comm_message_reactions`
+```
+id           UUID PK
+message_id   UUID FK → comm_messages
+user_id      UUID NOT NULL
+emoji        TEXT NOT NULL
+created_at   TIMESTAMP DEFAULT NOW()
+UNIQUE(message_id, user_id, emoji)
+```
+
+### Tabelle `comm_message_reads`
+```
+id              UUID PK
+conversation_id  UUID FK
+user_id         UUID NOT NULL
+last_read_msg_id  UUID FK → comm_messages
+last_read_at    TIMESTAMP DEFAULT NOW()
+```
+
+### Tabelle `comm_message_blocks` (Rich Content / Mini-Apps)
+```
+id           UUID PK
+message_id   UUID FK → comm_messages
+block_type   TEXT NOT NULL   -- 'file', 'image', 'audio', 'video', 
+                               -- 'markdown', 'html', 'miniapp', 
+                               -- 'action_card', 'contact_card', ...
+block_data   JSONB NOT NULL  -- typ-spezifische strukturierte Daten
+sort_order    INT DEFAULT 0
+```
+
+**Das ist der Schlüssel für Rich Content:**
+Eine Nachricht hat einen `content` (Text) plus beliebig viele `blocks` (strukturierte Elemente).
+
+---
+
+## Rich Content Transport
+
+### Block-Typen (erweiterbar durch Plugins)
+
+| block_type | Beschreibung | block_data Beispiel |
+|---|---|---|
+| `text` | Reiner Text (Fallback) | `{"text": "..."}` |
+| `markdown` | Markdown-Content | `{"markdown": "# Titel\n..."}` |
+| `html` | HTML-Content (sanitized) | `{"html": "<div>...</div>"}` |
+| `image` | Bild | `{"url": "...", "alt": "...", "width": 800}` |
+| `audio` | Audio-Datei | `{"url": "...", "duration": 120, "waveform": [...]}` |
+| `video` | Video-Datei | `{"url": "...", "duration": 60, "thumbnail": "..."}` |
+| `file` | Allgemeine Datei | `{"url": "...", "name": "...", "size": 1024}` |
+| `action_card` | Interaktive Karte mit Buttons | `{"title": "...", "body": "...", "actions": [{"label": "Öffnen", "url": "..."}]}` |
+| `contact_card` | Kontakt-Referenz | `{"contact_id": "...", "name": "..."}` |
+| `miniapp` | Eingebettete Mini-App | `{"app_id": "...", "config": {...}}` |
+
+### Mini-App System
+
+Mini-Apps sind kleine interaktive Komponenten, die **von Plugins registriert** und im Chat gerendert werden.
+
+```python
+# Plugin registriert eine Mini-App:
+class MiniAppRegistry:
+    def register(self, app_id: str, component: dict) -> None:
+        """Registriert eine Mini-App.
+        
+        component = {
+            'name': 'Lead Qualifier',
+            'icon': 'clipboard',
+            'render_schema': {...},  # JSON-Schema für Frontend
+            'handler': async function  # Backend-Handler
+        }
+        """
+```
+
+**Beispiel:** Ein Plugin `lead_qualifier` registriert eine Mini-App. Ein User schickt `/miniapp lead_qualifier` im Chat → eine Mini-App-Block wird erzeugt → Frontend rendert das interaktive Formular → Ergebnis wird als Nachricht zurückgeschrieben.
+
+### Nachricht mit Rich Content — Beispiel
+
+```json
+{
+  "id": "...",
+  "conversation_id": "...",
+  "sender_type": "ai",
+  "content": "Hier ist die Zusammenfassung der neuen Leads:",
+  "blocks": [
+    {
+      "block_type": "markdown",
+      "block_data": {
+        "markdown": "## 3 neue Leads\n- **Acme Corp** — €50k potential\n- **Globex** — €20k potential\n- **Initech** — €10k potential"
+      }
+    },
+    {
+      "block_type": "action_card",
+      "block_data": {
+        "title": "Nächste Schritte",
+        "body": "3 Leads warten auf Qualifizierung.",
+        "actions": [
+          {"label": "Alle öffnen", "action": "open_leads", "type": "primary"},
+          {"label": "Ignorieren", "action": "dismiss", "type": "secondary"}
+        ]
+      }
+    }
+  ]
+}
+```
+
+---
+
+## API
+
+### REST Endpoints
+
+```
+# Konversationen
+GET    /api/v1/comm/conversations                    -- Liste (für aktuellen User)
+POST   /api/v1/comm/conversations                    -- Neue Konversation
+GET    /api/v1/comm/conversations/{id}               -- Details + Teilnehmer
+PATCH  /api/v1/comm/conversations/{id}               -- Titel ändern, pinnen
+DELETE /api/v1/comm/conversations/{id}               -- Löschen/Verlassen
+
+# Teilnehmer
+POST   /api/v1/comm/conversations/{id}/participants  -- Teilnehmer hinzufügen
+DELETE /api/v1/comm/conversations/{id}/participants/{pid}  -- Entfernen
+
+# Nachrichten
+GET    /api/v1/comm/conversations/{id}/messages      -- Nachrichten (paginiert)
+POST   /api/v1/comm/conversations/{id}/messages      -- Nachricht senden
+PATCH  /api/v1/comm/messages/{id}                    -- Bearbeiten/Lesen
+DELETE /api/v1/comm/messages/{id}                    -- Löschen
+
+# Attachments
+POST   /api/v1/comm/messages/{id}/attachments         -- Datei hochladen
+GET    /api/v1/comm/attachments/{id}                  -- Datei herunterladen
+
+# Reaktionen
+POST   /api/v1/comm/messages/{id}/reactions          -- Reaktion hinzufügen
+DELETE /api/v1/comm/messages/{id}/reactions/{emoji}  -- Reaktion entfernen
+
+# Read State
+POST   /api/v1/comm/conversations/{id}/read          -- Als gelesen markieren
+
+# Mini-Apps
+GET    /api/v1/comm/miniapps                          -- Verfügbare Mini-Apps
+POST   /api/v1/comm/conversations/{id}/miniapps       -- Mini-App starten
+```
+
+### WebSocket
+
+```
+WS /api/v1/comm/ws
+
+# Client → Server
+{"type": "subscribe", "conversation_id": "..."}
+{"type": "typing", "conversation_id": "...", "is_typing": true}
+{"type": "ping"}
+
+# Server → Client
+{"type": "message.new", "conversation_id": "...", "message": {...}}
+{"type": "message.updated", "message": {...}}
+{"type": "message.deleted", "id": "..."}
+{"type": "participant.joined", "conversation_id": "...", "participant": {...}}
+{"type": "participant.left", "conversation_id": "...", "participant_id": "..."}
+{"type": "typing", "conversation_id": "...", "user_id": "...", "is_typing": true}
+{"type": "reaction.added", "message_id": "...", "emoji": "👍", "user_id": "..."}
+{"type": "conversation.updated", "conversation": {...}}
+{"type": "pong"}
+```
+
+---
+
+## UI-Konzept
+
+### MessageSidebar (ersetzt AISidebar)
+
+```
+┌──────────────────────────────────────────┐
+│  Kommunikation                    [×]    │
+├──────────────────────────────────────────┤
+│  🔍 Suche...                             │
+├──────────────────────────────────────────┤
+│  📌 Projekt Alpha                        │  ←angepinnt
+│     🤖 KI: 3 Leads zusammengefasst...    │
+│  ┌────────────────────────────────────┐  │
+│  │ Max: @KI fasse die Leads zusammen   │  │
+│  │ 🤖 KI: 3 neue Leads, 2 aus...       │  │
+│  │ Lisa: Super, danke!                 │  │
+│  │ ┌──────────────────────────────┐   │  │
+│  │ │ 📎 lead_report.pdf           │   │  │
+│  │ │ ──────────────────────────── │   │  │
+│  │ │ ## 3 neue Leads              │   │  │
+│  │ │ - **Acme Corp** — €50k       │   │  │
+│  │ │ ──────────────────────────── │   │  │
+│  │ │ [Öffnen]  [Archivieren]      │   │  │
+│  │ └──────────────────────────────┘   │  │
+│  └────────────────────────────────────┘  │
+│                                          │
+│  📌 Assistent (1:1 mit KI)               │
+│     🤖 47 Kontakte ohne Email...         │
+│                                          │
+│  👥 Sales Team                           │
+│     Max: Hat jemand die Q3-Zahlen?       │
+│                                          │
+│  🔔 System                              │
+│     3 neue Leads importiert             │
+│                                          │
+├──────────────────────────────────────────┤
+│  [📎] [Eingabefeld...]        [Senden]  │
+└──────────────────────────────────────────┘
+```
+
+### Konversations-Liste (links im Panel)
+- Angespinnte Konversationen oben (📌)
+- Ungelesene-Badge pro Konversation
+- Letzte Nachricht mit Sender-Icon (🤖/👤/🔔)
+- Klick → öffnet Konversation im Feed
+
+### Feed (Mitte)
+- Chronologische Nachrichten
+- Sender-Icon + Name pro Nachricht
+- Rich Content Blocks inline gerendert
+- Action-Cards mit Buttons
+- Datei-Anhänge mit Vorschau
+- Reaktionen (Emoji-Bar beim Hover)
+- Lesebestätigung (gelesen-Häkchen)
+
+### Eingabefeld (unten)
+- Text-Eingabe mit Markdown-Support
+- Datei-Anhang Button (📎)
+- Mini-App Picker (/command)
+- @Mention Support (@KI, @Max)
+- Senden-Button
+- Kontextsensitiv: in System-Konversation → kein Eingabefeld
+
+### Teilnehmer-Info
+- In Konversations-Header: Avatare aller Teilnehmer
+- Klick auf Avatar → Info-Popover
+- KI-Teilnehmer: zeigt Modell/Agent
+- System-Teilnehmer: zeigt Quelle
+
+### Räume
+- Konversationen können benannt werden (Titel editierbar)
+- Anpinnen möglich (📌)
+- Gruppierung durch Titel, nicht durch spezielle Raum-Logik
+- Ein "Raum" ist einfach eine benannte Konversation
+
+---
+
+## EventBus Integration
+
+### Events vom kommunikation Plugin
+
+```
+message.received     → {conversation_id, message, sender_type}
+message.sent         → {conversation_id, message}
+conversation.created → {conversation_id, participants, created_by}
+participant.joined   → {conversation_id, participant_type, participant_id}
+participant.left     → {conversation_id, participant_id}
+```
+
+### Events die andere Plugins hören
+
+```
+# ai_assistant hört auf:
+message.received → prüft ob @KI erwähnt oder AI Teilnehmer → generiert Response
+
+# system_notif hört auf (vom Core-System):
+lead.created    → erzeugt System-Nachricht
+contact.created → erzeugt System-Nachricht
+task.overdue     → erzeugt System-Nachricht
+
+# whatsapp_gateway hört auf:
+message.received → wenn Konversation WhatsApp-Teilnehmer hat → sende extern
+```
+
+---
+
+## Migration
+
+### Phase 1: Backend — Plugin `kommunikation`
+1. Neue Tabellen: `comm_conversations`, `comm_participants`, `comm_messages`, `comm_message_attachments`, `comm_message_blocks`, `comm_message_reactions`, `comm_message_reads`
+2. Participant Registry Interface
+3. REST-API + WebSocket
+4. Rich Content Block System
+5. Mini-App Registry Interface
+
+### Phase 2: Backend — Plugin `ai_assistant` anpassen
+1. `ParticipantHandler` implementieren
+2. Bei `kommunikation` registrieren
+3. Auf `message.received` hören → AI-Response generieren
+4. Streaming-Responses über WebSocket pushen
+5. Alte `AIChatSession`/`AIChatMessage` behalten für Abwärtskompatibilität
+
+### Phase 3: Backend — Plugin `system_notif` (neu)
+1. `ParticipantHandler` implementieren
+2. System-Events → Nachrichten in System-Konversation
+3. Bestehende Notifications migrieren
+4. Action-URLs als `action_card` Blocks
+
+### Phase 4: Frontend — MessageSidebar
+1. AISidebar → MessageSidebar umbauen
+2. Konversations-Liste mit Pinning
+3. Unified Feed mit Rich Content Rendering
+4. Eingabefeld mit Datei-Upload + @Mention
+5. WebSocket-Verbindung
+6. Mini-App Rendering Framework
+
+### Phase 5: Frontend — Rich Content Renderer
+1. Block-Renderer: Markdown, HTML, Image, Audio, Video, File
+2. Action-Card Renderer mit Button-Handler
+3. Mini-App Renderer (Plugin-basiert)
+4. Contact-Card, Lead-Card, etc.
+
+### Phase 6: Messenger-Gateway Plugins (später)
+1. `whatsapp_gateway` Plugin
+2. `telegram_gateway` Plugin
+3. `email_gateway` Plugin
+4. Jeweils: ParticipantHandler + Webhook-Routes + Gateway-Adapter
+
+---
+
+## Technische Entscheidungen
+
+### WebSocket vs Polling
+**WebSocket** — eine Verbindung pro User, pusht alle Konversationen.
+Grund: Real-time ist essenziell für Chat, und eine Verbindung für alles ist effizienter als Multiple Polling.
+
+### Rich Content: Blocks vs Inline
+**Blocks** — separate Tabelle `comm_message_blocks` mit `block_type` + `block_data`.
+Grund: Erweiterbar durch Plugins, strukturiert, frontend kann unbekannte Typen graceful ignorieren.
+
+### Mini-Apps: Plugin-basiert
+**Registry Pattern** — Plugins registrieren Mini-Apps bei `kommunikation`.
+Grund: Plugins können eigene Mini-Apps mitbringen, Frontend rendert sie dynamisch.
+
+### Räume: Keine separate Tabelle
+**Titel + Pinning** — eine Konversation mit Titel ist ein Raum.
+Grund: Minimalistisch, keine zusätzliche Komplexität, flexibel.
+
+### @Mention Detection
+**Im Backend** — `message.received` Event enthält geparste mentions.
+Grund: Zentrale Logik, alle Teilnehmer-Plugins bekommen saubere Daten.
+
+### Abwärtskompatibilität
+**Alte Tabellen behalten** — `ai_chat_sessions`, `ai_chat_messages`, `ai_conversations`, `ai_messages` bleiben erhalten.
+Grund: Bestehende Daten gehen nicht verloren, Migration schrittweise.
+
+---
+
+## Offene Fragen
+
+1. **Soll `kommunikation` das bestehende AI Copilot System (AIConversation/AIMessage) ersetzen oder parallel laufen?**
+   - Vorschlag: Parallel, langfristig migrieren
+
+2. **Datei-Speicherung:** DMS-Plugin nutzen oder eigener Speicher für Attachments?
+   - Vorschlag: DMS-Integration, `file_path` verweist auf DMS-Dokument
+
+3. **Berechtigungen:** Wer darf Konversationen erstellen? Wer darf Teilnehmer hinzufügen?
+   - Vorschlag: `comm:write` für erstellen, `comm:manage` für Teilnehmer verwalten
+
+4. **Gruppen-Chat-Limit:** Maximale Anzahl Teilnehmer?
+   - Vorschlag: Kein Limit, Performance-Test später
+
+5. **Nachrichten-Historie:** Endlos oder Paginierung mit Lazy-Loading?
+   - Vorschlag: Paginierung (50 pro Seite), Lazy-Load beim Scrollen
+
+6. **Suche:** Über alle Konversationen? Global mit unified_search Plugin?
+   - Vorschlag: Ja, `unified_search` Provider für `kommunikation`
+
+7. **Push-Notifications:** Browser-Notifications bei neuen Nachrichten?
+   - Vorschlag: Ja, über Notification API + Service Worker
+
+8. **Verschlüsselung:** E2E für bestimmte Konversationen?
+   - Vorschlag: Nein in Phase 1, später evaluieren
+
+---
+
+## Zusammenfassung
+
+```
+Ein Plugin (kommunikation)     → Chat-Infrastruktur + Rich Content + WebSocket
+Ein Interface (ParticipantHandler) → Plugins docken als Teilnehmer an
+Ein Datenmodell (3+Tabellen)   → Konversationen, Teilnehmer, Nachrichten + Blocks
+Eine UI (MessageSidebar)       → Ein Feed, eine Liste, ein Eingabefeld
+Eine WebSocket                 → Real-time für alles
+Ein EventBus                   → Plugins reagieren auf Nachrichten
+
+KI = Teilnehmer               → @KI in jedem Chat
+System = Teilnehmer           → Notifications als Nachrichten
+WhatsApp = Teilnehmer         → Externe Messenger andocken
+Mini-Apps = Plugin-Blocks      → Erweiterbar im Chat
+Räume = Benannte Chats         → Titel + Pinning
+```

frontend/src/api/comm.ts

@@ -0,0 +1,199 @@
+/**
+ * Communication plugin API client.
+ *
+ * All requests use the shared `apiClient` (`baseURL: '/api/v1'`) and target the
+ * kommunikation plugin routes under `/comm/...`.
+ */
+
+import { apiDelete, apiGet, apiPatch, apiPost } from './client';
+
+// ─── Types ───
+
+export interface Participant {
+  id: string;
+  conversation_id: string;
+  participant_id: string | null;
+  participant_type: string;
+  display_name: string | null;
+  role: string;
+}
+
+export interface Conversation {
+  id: string;
+  title: string | null;
+  is_locked: boolean;
+  locked_by: string | null;
+  is_direct: boolean;
+  is_archived: boolean;
+  is_pinned: boolean;
+  created_by: string | null;
+  created_by_type: string;
+  last_msg_at: string | null;
+  last_msg_preview: string | null;
+  last_msg_sender_type: string | null;
+  participants: Participant[];
+  unread_count: number;
+  metadata: Record<string, any>;
+}
+
+export interface MessageBlock {
+  id: string;
+  block_type: string;
+  block_data: Record<string, any>;
+  sort_order: number;
+}
+
+export interface MessageAttachment {
+  id: string;
+  file_id: string | null;
+  file_source: string;
+  file_name: string;
+  file_type: string;
+  file_size: number | null;
+  thumbnail_path: string | null;
+}
+
+export interface Message {
+  id: string;
+  conversation_id: string;
+  sender_id: string | null;
+  sender_type: string;
+  content: string;
+  content_format: string;
+  metadata: Record<string, any>;
+  reply_to_id: string | null;
+  is_pinned: boolean;
+  created_at: string | null;
+  edited_at: string | null;
+  blocks: MessageBlock[];
+  attachments: MessageAttachment[];
+  reactions: any[];
+}
+
+export interface ConversationListResponse {
+  items: Conversation[];
+  total: number;
+}
+
+export interface MessageListResponse {
+  items: Message[];
+  total: number;
+  page: number;
+  page_size: number;
+}
+
+export interface BlockType {
+  type: string;
+  label: string;
+  schema: Record<string, any>;
+}
+
+export interface MiniApp {
+  id: string;
+  name: string;
+  description: string;
+  config_schema: Record<string, any>;
+}
+
+// ─── Conversations ───
+
+export const listConversations = (archived?: boolean) =>
+  apiGet<ConversationListResponse>('/comm/conversations', {
+    params: archived !== undefined ? { archived } : {},
+  });
+
+export const createConversation = (data: {
+  title?: string;
+  participant_ids?: string[];
+  is_direct?: boolean;
+  initial_message?: string;
+}) => apiPost<Conversation>('/comm/conversations', data);
+
+export const getConversation = (id: string) =>
+  apiGet<Conversation>(`/comm/conversations/${id}`);
+
+export const updateConversation = (id: string, data: { title?: string; is_archived?: boolean }) =>
+  apiPatch<Conversation>(`/comm/conversations/${id}`, data);
+
+export const leaveConversation = (id: string) =>
+  apiDelete<{ success: boolean }>(`/comm/conversations/${id}`);
+
+export const pinConversation = (id: string) =>
+  apiPost<{ success: boolean }>(`/comm/conversations/${id}/pin`);
+
+export const unpinConversation = (id: string) =>
+  apiDelete<{ success: boolean }>(`/comm/conversations/${id}/pin`);
+
+export const muteConversation = (id: string) =>
+  apiPost<{ success: boolean }>(`/comm/conversations/${id}/mute`);
+
+export const unmuteConversation = (id: string) =>
+  apiDelete<{ success: boolean }>(`/comm/conversations/${id}/mute`);
+
+// ─── Participants ───
+
+export const addParticipant = (
+  convId: string,
+  data: { participant_id: string; participant_type: string; role?: string },
+) => apiPost<Participant>(`/comm/conversations/${convId}/participants`, data);
+
+export const removeParticipant = (convId: string, pid: string) =>
+  apiDelete<{ success: boolean }>(`/comm/conversations/${convId}/participants/${pid}`);
+
+export const changeParticipantRole = (convId: string, pid: string, role: string) =>
+  apiPatch<Participant>(`/comm/conversations/${convId}/participants/${pid}`, { role });
+
+// ─── Messages ───
+
+export const getMessages = (convId: string, page = 1, pageSize = 50, before?: string) =>
+  apiGet<MessageListResponse>(`/comm/conversations/${convId}/messages`, {
+    params: { page, page_size: pageSize, ...(before ? { before } : {}) },
+  });
+
+export const sendMessage = (
+  convId: string,
+  data: {
+    content: string;
+    content_format?: string;
+    blocks?: Array<{ block_type: string; block_data: Record<string, any> }>;
+    reply_to_id?: string;
+    attachments?: Array<Record<string, any>>;
+  },
+) => apiPost<Message>(`/comm/conversations/${convId}/messages`, data);
+
+export const editMessage = (id: string, data: { content?: string }) =>
+  apiPatch<Message>(`/comm/messages/${id}`, data);
+
+export const deleteMessage = (id: string) =>
+  apiDelete<{ success: boolean }>(`/comm/messages/${id}`);
+
+// ─── Reactions ───
+
+export const addReaction = (msgId: string, emoji: string) =>
+  apiPost<any>(`/comm/messages/${msgId}/reactions`, { emoji });
+
+export const removeReaction = (msgId: string, emoji: string) =>
+  apiDelete<{ success: boolean }>(`/comm/messages/${msgId}/reactions/${encodeURIComponent(emoji)}`);
+
+// ─── Read State ───
+
+export const markRead = (convId: string, lastReadMsgId?: string) =>
+  apiPost<{ success: boolean }>(`/comm/conversations/${convId}/read`, {
+    last_read_msg_id: lastReadMsgId,
+  });
+
+// ─── Mini-Apps ───
+
+export const listMiniApps = () =>
+  apiGet<{ items: MiniApp[] }>('/comm/miniapps');
+
+export const startMiniApp = (convId: string, appId: string, config?: Record<string, any>) =>
+  apiPost<Message>(`/comm/conversations/${convId}/miniapps`, {
+    app_id: appId,
+    config: config || {},
+  });
+
+// ─── Block Types ───
+
+export const getBlockTypes = () =>
+  apiGet<{ items: BlockType[] }>('/comm/block-types');

frontend/src/components/comm/blocks/ActionCardBlock.tsx

@@ -0,0 +1,62 @@
+import React from 'react';
+import type { MessageBlock } from '@/store/commStore';
+
+interface ActionCardBlockProps {
+  block: MessageBlock;
+}
+
+interface ActionItem {
+  label: string;
+  action: string;
+  type?: 'primary' | 'secondary';
+}
+
+const ActionCardBlock: React.FC<ActionCardBlockProps> = ({ block }) => {
+  const { title, body, actions } = block.block_data;
+
+  const cardTitle: string = title || '';
+  const cardBody: string = body || '';
+  const actionList: ActionItem[] = Array.isArray(actions) ? actions : [];
+
+  const handleActionClick = (action: ActionItem) => {
+    if (action.action === 'dismiss') {
+      // Frontend handles dismiss — no-op here, parent component can wire up
+      return;
+    }
+    // Treat as URL
+    window.open(action.action, '_blank', 'noopener,noreferrer');
+  };
+
+  return (
+    <div className="border border-secondary-200 rounded-lg p-4 shadow-sm bg-white space-y-2">
+      {cardTitle && (
+        <h4 className="text-sm font-semibold text-secondary-800">{cardTitle}</h4>
+      )}
+      {cardBody && (
+        <p className="text-sm text-secondary-600">{cardBody}</p>
+      )}
+      {actionList.length > 0 && (
+        <div className="flex flex-wrap gap-2 pt-1">
+          {actionList.map((action, idx) => {
+            const isPrimary = action.type !== 'secondary';
+            return (
+              <button
+                key={idx}
+                onClick={() => handleActionClick(action)}
+                className={
+                  isPrimary
+                    ? 'px-3 py-1.5 text-sm rounded-lg bg-primary-600 text-white hover:bg-primary-700 transition-colors'
+                    : 'px-3 py-1.5 text-sm rounded-lg bg-secondary-100 text-secondary-700 hover:bg-secondary-200 transition-colors'
+                }
+              >
+                {action.label || 'Aktion'}
+              </button>
+            );
+          })}
+        </div>
+      )}
+    </div>
+  );
+};
+
+export default ActionCardBlock;

frontend/src/components/comm/blocks/AudioBlock.tsx

@@ -0,0 +1,41 @@
+import React from 'react';
+import type { MessageBlock } from '@/store/commStore';
+
+interface AudioBlockProps {
+  block: MessageBlock;
+}
+
+function formatDuration(seconds: number | undefined): string | null {
+  if (typeof seconds !== 'number' || seconds <= 0) return null;
+  const mins = Math.floor(seconds / 60);
+  const secs = Math.floor(seconds % 60);
+  return `${mins}:${secs.toString().padStart(2, '0')}`;
+}
+
+const AudioBlock: React.FC<AudioBlockProps> = ({ block }) => {
+  const { url, duration } = block.block_data;
+
+  if (!url) {
+    return null;
+  }
+
+  const durationLabel = formatDuration(duration);
+
+  return (
+    <div className="space-y-1">
+      <audio
+        src={url}
+        controls
+        className="w-full rounded-lg"
+        preload="metadata"
+      />
+      {durationLabel && (
+        <p className="text-xs text-secondary-500">
+          Dauer: {durationLabel}
+        </p>
+      )}
+    </div>
+  );
+};
+
+export default AudioBlock;

frontend/src/components/comm/blocks/BlockRenderer.tsx

@@ -0,0 +1,75 @@
+import React from 'react';
+import type { MessageBlock } from '@/store/commStore';
+import MarkdownBlock from './MarkdownBlock';
+import HtmlBlock from './HtmlBlock';
+import ImageBlock from './ImageBlock';
+import AudioBlock from './AudioBlock';
+import VideoBlock from './VideoBlock';
+import FileBlock from './FileBlock';
+import ActionCardBlock from './ActionCardBlock';
+import ContactCardBlock from './ContactCardBlock';
+import MiniAppBlock from './MiniAppBlock';
+
+interface BlockRendererProps {
+  blocks: MessageBlock[];
+}
+
+const BlockRenderer: React.FC<BlockRendererProps> = ({ blocks }) => {
+  if (!blocks || blocks.length === 0) {
+    return null;
+  }
+
+  // Sort blocks by sort_order to ensure correct rendering sequence
+  const sortedBlocks = [...blocks].sort((a, b) => a.sort_order - b.sort_order);
+
+  return (
+    <div className="space-y-2">
+      {sortedBlocks.map((block) => {
+        const renderBlock = (): React.ReactNode => {
+          switch (block.block_type) {
+            case 'text':
+              // Text blocks: render as plain text in a styled div
+              return (
+                <div className="text-sm whitespace-pre-wrap break-words">
+                  {block.block_data.text || block.block_data.content || ''}
+                </div>
+              );
+            case 'markdown':
+              return <MarkdownBlock block={block} />;
+            case 'html':
+              return <HtmlBlock block={block} />;
+            case 'image':
+              return <ImageBlock block={block} />;
+            case 'audio':
+              return <AudioBlock block={block} />;
+            case 'video':
+              return <VideoBlock block={block} />;
+            case 'file':
+              return <FileBlock block={block} />;
+            case 'action_card':
+              return <ActionCardBlock block={block} />;
+            case 'contact_card':
+              return <ContactCardBlock block={block} />;
+            case 'miniapp':
+              return <MiniAppBlock block={block} />;
+            default:
+              // Fallback for unknown block types
+              return (
+                <div className="text-xs text-secondary-400 italic p-2 rounded bg-secondary-50">
+                  Unbekannter Block-Typ: {block.block_type}
+                </div>
+              );
+          }
+        };
+
+        return (
+          <div key={block.id} className="block-wrapper">
+            {renderBlock()}
+          </div>
+        );
+      })}
+    </div>
+  );
+};
+
+export default BlockRenderer;

frontend/src/components/comm/blocks/ContactCardBlock.tsx

@@ -0,0 +1,52 @@
+import React from 'react';
+import type { MessageBlock } from '@/store/commStore';
+
+interface ContactCardBlockProps {
+  block: MessageBlock;
+}
+
+const ContactCardBlock: React.FC<ContactCardBlockProps> = ({ block }) => {
+  const { contact_id, name } = block.block_data;
+
+  const contactName: string = name || 'Unbekannter Kontakt';
+  const contactId: string = contact_id || '';
+  const linkHref = contactId ? `/contacts/${contactId}` : '#';
+
+  // Generate initials for avatar placeholder
+  const initials = contactName
+    .split(' ')
+    .map((part) => part.charAt(0).toUpperCase())
+    .slice(0, 2)
+    .join('');
+
+  return (
+    <a
+      href={linkHref}
+      className="flex items-center gap-3 p-3 rounded-lg border border-secondary-200 bg-white shadow-sm hover:shadow-md hover:border-primary-300 transition-all"
+    >
+      <div className="flex-shrink-0 w-10 h-10 rounded-full bg-primary-100 text-primary-700 flex items-center justify-center text-sm font-semibold">
+        {initials || '?'}
+      </div>
+      <div className="flex-1 min-w-0">
+        <p className="text-sm font-medium text-secondary-700 truncate">{contactName}</p>
+        <p className="text-xs text-secondary-400">Kontakt anzeigen</p>
+      </div>
+      <svg
+        className="w-4 h-4 text-secondary-400 flex-shrink-0"
+        fill="none"
+        viewBox="0 0 24 24"
+        stroke="currentColor"
+        aria-hidden="true"
+      >
+        <path
+          strokeLinecap="round"
+          strokeLinejoin="round"
+          strokeWidth={2}
+          d="M9 5l7 7-7 7"
+        />
+      </svg>
+    </a>
+  );
+};
+
+export default ContactCardBlock;

frontend/src/components/comm/blocks/FileBlock.tsx

@@ -0,0 +1,85 @@
+import React from 'react';
+import type { MessageBlock } from '@/store/commStore';
+
+interface FileBlockProps {
+  block: MessageBlock;
+}
+
+function formatFileSize(bytes: number | undefined): string {
+  if (typeof bytes !== 'number' || bytes <= 0) return '';
+  if (bytes < 1024) return `${bytes} B`;
+  if (bytes < 1024 * 1024) return `${(bytes / 1024).toFixed(1)} KB`;
+  if (bytes < 1024 * 1024 * 1024) return `${(bytes / (1024 * 1024)).toFixed(1)} MB`;
+  return `${(bytes / (1024 * 1024 * 1024)).toFixed(1)} GB`;
+}
+
+const fileIcon = (
+  <svg
+    className="w-8 h-8 text-secondary-400"
+    fill="none"
+    viewBox="0 0 24 24"
+    stroke="currentColor"
+    aria-hidden="true"
+  >
+    <path
+      strokeLinecap="round"
+      strokeLinejoin="round"
+      strokeWidth={1.5}
+      d="M14 2H6a2 2 0 00-2 2v16a2 2 0 002 2h12a2 2 0 002-2V8z M14 2v6h6 M8 13h8 M8 17h5"
+    />
+  </svg>
+);
+
+const downloadIcon = (
+  <svg
+    className="w-4 h-4"
+    fill="none"
+    viewBox="0 0 24 24"
+    stroke="currentColor"
+    aria-hidden="true"
+  >
+    <path
+      strokeLinecap="round"
+      strokeLinejoin="round"
+      strokeWidth={2}
+      d="M4 16v1a3 3 0 003 3h10a3 3 0 003-3v-1m-4-4l-4 4m0 0l-4-4m4 4V4"
+    />
+  </svg>
+);
+
+const FileBlock: React.FC<FileBlockProps> = ({ block }) => {
+  const { url, name, size } = block.block_data;
+
+  if (!url && !name) {
+    return null;
+  }
+
+  const fileName: string = name || 'Datei';
+  const fileSizeLabel = formatFileSize(size);
+
+  return (
+    <div className="flex items-center gap-3 p-3 rounded-lg border border-secondary-200 bg-white shadow-sm">
+      <div className="flex-shrink-0">{fileIcon}</div>
+      <div className="flex-1 min-w-0">
+        <p className="text-sm font-medium text-secondary-700 truncate">{fileName}</p>
+        {fileSizeLabel && (
+          <p className="text-xs text-secondary-400">{fileSizeLabel}</p>
+        )}
+      </div>
+      {url && (
+        <a
+          href={url}
+          download={fileName}
+          target="_blank"
+          rel="noopener noreferrer"
+          className="flex-shrink-0 p-2 rounded-lg bg-primary-500 text-white hover:bg-primary-600 transition-colors"
+          aria-label={`Datei herunterladen: ${fileName}`}
+        >
+          {downloadIcon}
+        </a>
+      )}
+    </div>
+  );
+};
+
+export default FileBlock;

frontend/src/components/comm/blocks/HtmlBlock.tsx

@@ -0,0 +1,45 @@
+import React from 'react';
+import type { MessageBlock } from '@/store/commStore';
+
+interface HtmlBlockProps {
+  block: MessageBlock;
+}
+
+/**
+ * Basic HTML sanitization: removes <script> tags and event handler attributes.
+ * This is a minimal sanitizer — for production use DOMPurify or similar.
+ */
+function sanitizeHtml(html: string): string {
+  let sanitized = html;
+  // Remove <script>...</script> blocks (including content)
+  sanitized = sanitized.replace(/<script\b[^<]*(?:(?!<\/script>)<[^<]*)*<\/script>/gi, '');
+  // Remove <script ...> self-referencing or incomplete tags
+  sanitized = sanitized.replace(/<script\b[^>]*>/gi, '');
+  // Remove on* event handler attributes (onclick, onload, onerror, etc.)
+  sanitized = sanitized.replace(/\son\w+\s*=\s*"[^"]*"/gi, '');
+  sanitized = sanitized.replace(/\son\w+\s*=\s*'[^']*'/gi, '');
+  sanitized = sanitized.replace(/\son\w+\s*=\s*[^\s>]+/gi, '');
+  // Remove javascript: URLs in href/src
+  sanitized = sanitized.replace(/(href|src)\s*=\s*"javascript:[^"]*"/gi, '$1="#"');
+  sanitized = sanitized.replace(/(href|src)\s*=\s*'javascript:[^']*'/gi, '$1="#"');
+  return sanitized;
+}
+
+const HtmlBlock: React.FC<HtmlBlockProps> = ({ block }) => {
+  const rawHtml: string = block.block_data.html || '';
+
+  if (!rawHtml) {
+    return null;
+  }
+
+  const sanitized = sanitizeHtml(rawHtml);
+
+  return (
+    <div
+      className="prose prose-sm max-w-none text-inherit"
+      dangerouslySetInnerHTML={{ __html: sanitized }}
+    />
+  );
+};
+
+export default HtmlBlock;

frontend/src/components/comm/blocks/ImageBlock.tsx

@@ -0,0 +1,35 @@
+import React from 'react';
+import type { MessageBlock } from '@/store/commStore';
+
+interface ImageBlockProps {
+  block: MessageBlock;
+}
+
+const ImageBlock: React.FC<ImageBlockProps> = ({ block }) => {
+  const { url, alt, width } = block.block_data;
+
+  if (!url) {
+    return null;
+  }
+
+  const imageAlt: string = alt || '';
+  const imageWidth: number | undefined = typeof width === 'number' ? width : undefined;
+
+  return (
+    <div className="space-y-1">
+      <a href={url} target="_blank" rel="noopener noreferrer" className="block">
+        <img
+          src={url}
+          alt={imageAlt}
+          width={imageWidth}
+          className="rounded-lg max-w-full shadow-sm cursor-pointer hover:shadow-md transition-shadow"
+        />
+      </a>
+      {imageAlt && (
+        <p className="text-xs text-secondary-500 italic">{imageAlt}</p>
+      )}
+    </div>
+  );
+};
+
+export default ImageBlock;

frontend/src/components/comm/blocks/MarkdownBlock.tsx

@@ -0,0 +1,59 @@
+import React from 'react';
+import ReactMarkdown from 'react-markdown';
+import type { MessageBlock } from '@/store/commStore';
+
+interface MarkdownBlockProps {
+  block: MessageBlock;
+}
+
+const MarkdownBlock: React.FC<MarkdownBlockProps> = ({ block }) => {
+  const markdown: string = block.block_data.markdown || block.block_data.content || '';
+
+  if (!markdown) {
+    return null;
+  }
+
+  return (
+    <div className="prose prose-sm max-w-none text-inherit">
+      <ReactMarkdown
+        components={{
+          p: ({ children }) => <p className="mb-1 last:mb-0">{children}</p>,
+          ul: ({ children }) => <ul className="list-disc pl-4 mb-1">{children}</ul>,
+          ol: ({ children }) => <ol className="list-decimal pl-4 mb-1">{children}</ol>,
+          code: ({ children, className }) => {
+            const isInline = !className;
+            if (isInline) {
+              return (
+                <code className="px-1 py-0.5 rounded bg-black/10 text-xs font-mono">
+                  {children}
+                </code>
+              );
+            }
+            return (
+              <pre className="p-2 rounded bg-black/10 overflow-x-auto">
+                <code className="text-xs font-mono">{children}</code>
+              </pre>
+            );
+          },
+          h1: ({ children }) => <h1 className="text-base font-bold mb-1">{children}</h1>,
+          h2: ({ children }) => <h2 className="text-sm font-bold mb-1">{children}</h2>,
+          h3: ({ children }) => <h3 className="text-sm font-semibold mb-1">{children}</h3>,
+          a: ({ children, href }) => (
+            <a href={href} target="_blank" rel="noopener noreferrer" className="underline">
+              {children}
+            </a>
+          ),
+          blockquote: ({ children }) => (
+            <blockquote className="border-l-2 border-current/30 pl-2 italic opacity-80">
+              {children}
+            </blockquote>
+          ),
+        }}
+      >
+        {markdown}
+      </ReactMarkdown>
+    </div>
+  );
+};
+
+export default MarkdownBlock;

frontend/src/components/comm/blocks/MiniAppBlock.tsx

@@ -0,0 +1,50 @@
+import React from 'react';
+import type { MessageBlock } from '@/store/commStore';
+
+interface MiniAppBlockProps {
+  block: MessageBlock;
+}
+
+const MiniAppBlock: React.FC<MiniAppBlockProps> = ({ block }) => {
+  const { app_id, config } = block.block_data;
+
+  const appId: string = app_id || 'Unbekannt';
+  const hasConfig = config && typeof config === 'object' && Object.keys(config).length > 0;
+
+  return (
+    <div className="border-2 border-dashed border-secondary-300 rounded-lg p-4 text-center bg-secondary-50">
+      <div className="flex flex-col items-center gap-2">
+        <svg
+          className="w-8 h-8 text-secondary-400"
+          fill="none"
+          viewBox="0 0 24 24"
+          stroke="currentColor"
+          aria-hidden="true"
+        >
+          <path
+            strokeLinecap="round"
+            strokeLinejoin="round"
+            strokeWidth={1.5}
+            d="M4 6a2 2 0 012-2h12a2 2 0 012 2v12a2 2 0 01-2 2H6a2 2 0 01-2-2V6z M9 9h6v6H9z"
+          />
+        </svg>
+        <p className="text-sm font-medium text-secondary-600">
+          Mini-App: {appId}
+        </p>
+        <p className="text-xs text-secondary-400">
+          Mini-Apps werden in Zukunft vollständig gerendert.
+        </p>
+        {hasConfig && (
+          <details className="text-xs text-secondary-400 mt-1">
+            <summary className="cursor-pointer hover:text-secondary-600">Konfiguration</summary>
+            <pre className="mt-1 p-2 rounded bg-white text-left overflow-x-auto">
+              {JSON.stringify(config, null, 2)}
+            </pre>
+          </details>
+        )}
+      </div>
+    </div>
+  );
+};
+
+export default MiniAppBlock;

frontend/src/components/comm/blocks/VideoBlock.tsx

@@ -0,0 +1,30 @@
+import React from 'react';
+import type { MessageBlock } from '@/store/commStore';
+
+interface VideoBlockProps {
+  block: MessageBlock;
+}
+
+const VideoBlock: React.FC<VideoBlockProps> = ({ block }) => {
+  const { url, thumbnail } = block.block_data;
+
+  if (!url) {
+    return null;
+  }
+
+  const poster: string | undefined = typeof thumbnail === 'string' ? thumbnail : undefined;
+
+  return (
+    <div className="space-y-1">
+      <video
+        src={url}
+        controls
+        poster={poster}
+        className="w-full rounded-lg"
+        preload="metadata"
+      />
+    </div>
+  );
+};
+
+export default VideoBlock;

frontend/src/components/comm/blocks/index.ts

@@ -0,0 +1,10 @@
+export { default as BlockRenderer } from './BlockRenderer';
+export { default as MarkdownBlock } from './MarkdownBlock';
+export { default as HtmlBlock } from './HtmlBlock';
+export { default as ImageBlock } from './ImageBlock';
+export { default as AudioBlock } from './AudioBlock';
+export { default as VideoBlock } from './VideoBlock';
+export { default as FileBlock } from './FileBlock';
+export { default as ActionCardBlock } from './ActionCardBlock';
+export { default as ContactCardBlock } from './ContactCardBlock';
+export { default as MiniAppBlock } from './MiniAppBlock';

frontend/src/components/comm/blocks/test_report.md

@@ -0,0 +1,66 @@
+# Test Report: Phase 5 — Rich Content Block-Renderer
+
+## Task
+Implement Frontend Rich Content Block-Renderer Components for Unified Messaging System.
+
+## Files Created
+
+| File | Lines | Purpose |
+|------|-------|---------|
+| `BlockRenderer.tsx` | 75 | Main dispatcher — switches on `block_type`, renders appropriate sub-renderer, fallback for unknown types |
+| `MarkdownBlock.tsx` | 59 | Renders Markdown via `react-markdown` (already installed), custom component styling |
+| `HtmlBlock.tsx` | 45 | Renders sanitized HTML via `dangerouslySetInnerHTML` — strips `<script>`, `on*` handlers, `javascript:` URLs |
+| `ImageBlock.tsx` | 35 | Renders image with alt caption, optional width, opens in new tab on click |
+| `AudioBlock.tsx` | 41 | Renders `<audio>` player with controls, shows formatted duration |
+| `VideoBlock.tsx` | 30 | Renders `<video>` player with controls, optional thumbnail poster |
+| `FileBlock.tsx` | 85 | Renders file card with icon, name, size, download link |
+| `ActionCardBlock.tsx` | 62 | Renders interactive card with title, body, action buttons (primary/secondary styling) |
+| `ContactCardBlock.tsx` | 52 | Renders contact reference card with avatar initials, links to `/contacts/{id}` |
+| `MiniAppBlock.tsx` | 50 | Renders placeholder for mini-apps with app_id and config details |
+| `index.ts` | 10 | Barrel export for all components |
+
+**Total: 544 lines across 11 files**
+
+## Files Modified
+
+| File | Change |
+|------|--------|
+| `MessageSidebar.tsx` | Added `BlockRenderer` import; replaced inline block rendering (40 lines) with `<BlockRenderer blocks={msg.blocks} />` (6 lines) |
+
+## TypeScript Compilation Check
+
+```
+cd /a0/usr/workdir/leocrm-fix/frontend && npx tsc --noEmit 2>&1 | grep -E 'comm/blocks|MessageSidebar'
+→ No errors in block components or MessageSidebar
+```
+
+### Pre-existing errors (NOT introduced by this task):
+- `src/pages/Dms.tsx(553,13)`: `onRangeSelect` prop mismatch in `FileExplorerProps` — pre-existing, unrelated.
+
+## Backend Compatibility
+
+All block types match `content_types.py` definitions:
+- `text` → `block_data.text`
+- `markdown` → `block_data.markdown` (also falls back to `block_data.content`)
+- `html` → `block_data.html`
+- `image` → `block_data.url`, `block_data.alt`, `block_data.width`
+- `audio` → `block_data.url`, `block_data.duration`
+- `video` → `block_data.url`, `block_data.thumbnail`
+- `file` → `block_data.url`, `block_data.name`, `block_data.size`
+- `action_card` → `block_data.title`, `block_data.body`, `block_data.actions`
+- `contact_card` → `block_data.contact_id`, `block_data.name`
+- `miniapp` → `block_data.app_id`, `block_data.config`
+
+## Smoke Test
+
+- **TypeScript**: `npx tsc --noEmit` passes with zero new errors from block components.
+- **Import chain**: `BlockRenderer` imports all 9 sub-renderers + types from `@/store/commStore` — all resolve correctly.
+- **MessageSidebar integration**: Inline block rendering replaced with `<BlockRenderer>` component — compiles cleanly.
+- **Barrel export**: `index.ts` exports all 10 components for clean imports.
+
+## Notes
+
+- `react-markdown` was already in `package.json` (`^10.1.0`) — used directly.
+- HTML sanitization is minimal (regex-based). For production, consider `DOMPurify`.
+- Unknown block types render a fallback message ("Unbekannter Block-Typ: {type}") per spec.
+- Blocks are sorted by `sort_order` before rendering.

frontend/src/components/layout/AppShell.tsx

@@ -3,7 +3,7 @@ import { Outlet, useLocation } from 'react-router-dom';
 import { Sidebar } from './Sidebar';
 import { TopBar } from './TopBar';
 import { PluginToolbar } from './PluginToolbar';
-import { AISidebar } from './AISidebar';
+import { MessageSidebar } from './MessageSidebar';
 import { ToastContainer } from '@/components/ui/Toast';
 import { useAIContext } from '@/hooks/useAIContext';
 
@@ -13,8 +13,8 @@ export function AppShell() {
   // Track context for AI Proactive suggestions
   useAIContext();
 
-  // Hide AI sidebar on the AI Assistant page itself
+  // Hide message sidebar on the AI Assistant page itself
-  const showAISidebar = !location.pathname.startsWith('/ai-assistant');
+  const showMessageSidebar = !location.pathname.startsWith('/ai-assistant');
 
   return (
     <div className="flex h-screen overflow-hidden bg-secondary-50" data-testid="app-shell">
@@ -34,8 +34,8 @@ export function AppShell() {
           </main>
         </div>
       </div>
-      {/* AI Sidebar — full height, right of TopBar and Toolbar */}
+      {/* Message Sidebar — full height, right of TopBar and Toolbar */}
-      {showAISidebar && <AISidebar />}
+      {showMessageSidebar && <MessageSidebar />}
       <ToastContainer />
     </div>
   );

frontend/src/components/layout/MessageSidebar.tsx

@@ -0,0 +1,683 @@
+import React, { useState, useEffect, useRef, useCallback } from 'react';
+import { ResizablePanel } from '@/components/ui/ResizablePanel';
+import { useUIStore } from '@/store/uiStore';
+import { useCommStore } from '@/store/commStore';
+import { useTranslation } from 'react-i18next';
+import { useUsers, useGroups } from '@/api/hooks';
+import { Avatar } from '@/components/ui/Avatar';
+import {
+  listConversations,
+  getMessages,
+  sendMessage,
+  markRead,
+  createConversation,
+} from '@/api/comm';
+import { useCommWebSocket } from '@/hooks/useCommWebSocket';
+import type { Conversation, Message } from '@/store/commStore';
+import { BlockRenderer } from '@/components/comm/blocks';
+
+// ─── Icons (identical to AISidebar) ───
+
+const robotIcon = (className: string) => (
+  <svg className={className} fill="none" viewBox="0 0 24 24" stroke="currentColor" aria-hidden="true">
+    <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M12 2a4 4 0 014 4v1h1a3 3 0 013 3v6a3 3 0 01-3 3h-1v1a4 4 0 01-4 4H8a4 4 0 01-4-4v-1H3a3 3 0 01-3-3V10a3 3 0 013-3h1V6a4 4 0 014-4z M9 10h.01M15 10h.01M9 15h6" />
+  </svg>
+);
+
+const bellIcon = (className: string) => (
+  <svg className={className} fill="none" viewBox="0 0 24 24" stroke="currentColor" aria-hidden="true">
+    <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M15 17h5l-1.405-1.405A2.032 2.032 0 0118 14.158V11a6.002 6.002 0 00-4-5.659V5a2 2 0 10-4 0v.341C7.67 6.165 6 8.388 6 11v3.159c0 .538-.214 1.055-.595 1.436L4 17h5m6 0v1a3 3 0 11-6 0v-1m6 0H9" />
+  </svg>
+);
+
+const bulbIcon = (className: string) => (
+  <svg className={className} fill="none" viewBox="0 0 24 24" stroke="currentColor" aria-hidden="true">
+    <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M9.663 17h4.673M12 3v1m6.364 1.636l-.707.707M21 12h-1M4 12H3m3.343-5.657l-.707-.707m2.828 9.9a5 5 0 117.072 0l-.548.547A3.374 3.374 0 0014 18.469V19a2 2 0 11-4 0v-.531c0-.895-.356-1.754-.988-2.386l-.548-.547z" />
+  </svg>
+);
+
+const teamIcon = (className: string) => (
+  <svg className={className} fill="none" viewBox="0 0 24 24" stroke="currentColor" aria-hidden="true">
+    <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M17 20h5v-2a3 3 0 00-5.356-1.857M17 20H7m10 0v-2c0-.656-.126-1.283-.356-1.857M7 20H2v-2a3 3 0 015.356-1.857M7 20v-2c0-.656.126-1.283.356-1.857m0 0a5.002 5.002 0 019.288 0M15 7a3 3 0 11-6 0 3 3 0 016 0zm6-3a2 2 0 11-4 0 2 2 0 014 0zM7 10a2 2 0 11-4 0 2 2 0 014 0z" />
+  </svg>
+);
+
+const chatBubbleIcon = (className: string) => (
+  <svg className={className} fill="none" viewBox="0 0 24 24" stroke="currentColor" aria-hidden="true">
+    <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M8 12h.01M12 12h.01M16 12h.01M21 12c0 4.418-4.03 8-9 8a9.863 9.863 0 01-4.255-.949L3 20l1.395-3.72C3.512 15.042 3 13.574 3 12c0-4.418 4.03-8 9-8s9 3.582 9 8z" />
+  </svg>
+);
+
+const chevronRightIcon = (
+  <svg className="w-4 h-4" fill="none" viewBox="0 0 24 24" stroke="currentColor" aria-hidden="true">
+    <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M9 5l7 7-7 7" />
+  </svg>
+);
+
+const sendIcon = (
+  <svg className="w-4 h-4" fill="none" viewBox="0 0 24 24" stroke="currentColor" aria-hidden="true">
+    <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M12 19l9 2-9-18-9 18 9-2zm0 0v-8" />
+  </svg>
+);
+
+const pinIcon = (
+  <svg className="w-3.5 h-3.5" fill="none" viewBox="0 0 24 24" stroke="currentColor" aria-hidden="true">
+    <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M5 5a2 2 0 012-2h10a2 2 0 012 2v16l-7-3.5L5 21V5z" />
+  </svg>
+);
+
+// ─── Types ───
+
+type SidebarView = 'conversations' | 'team';
+
+interface QuickAccessDef {
+  key: string;
+  label: string;
+  icon: (cls: string) => React.ReactNode;
+  testId: string;
+  view: SidebarView;
+  filterPinned?: string;
+}
+
+// ─── Team Panel (reused from AISidebar) ───
+
+function TeamPanel({ onStartDirectChat }: { onStartDirectChat: (userId: string, userName: string) => void }) {
+  const { data: usersData, isLoading: usersLoading } = useUsers();
+  const { data: groupsData, isLoading: groupsLoading } = useGroups();
+  const users: any[] = usersData?.items || [];
+  const groups: any[] = groupsData?.items || [];
+
+  return (
+    <div className="flex flex-col h-full overflow-y-auto p-3 gap-3" data-testid="team-panel">
+      <div>
+        <h3 className="text-xs font-semibold text-secondary-500 uppercase tracking-wide mb-2">Mitarbeiter</h3>
+        {usersLoading ? (
+          <p className="text-sm text-secondary-400">Laden...</p>
+        ) : users.length === 0 ? (
+          <p className="text-sm text-secondary-400">Keine Mitarbeiter</p>
+        ) : (
+          <div className="space-y-1">
+            {users.map((u) => (
+              <button
+                key={u.id}
+                onClick={() => onStartDirectChat(u.id, u.name)}
+                className="flex items-center gap-2 px-2 py-1.5 rounded-lg hover:bg-secondary-50 transition-colors w-full text-left"
+              >
+                <div className="relative flex-shrink-0">
+                  <Avatar name={u.name} size="sm" />
+                  <span className="absolute bottom-0 right-0 w-2.5 h-2.5 rounded-full border-2 border-white bg-secondary-300" aria-label="offline" />
+                </div>
+                <div className="flex-1 min-w-0">
+                  <p className="text-sm font-medium text-secondary-700 truncate">{u.name}</p>
+                  <p className="text-xs text-secondary-400 truncate">{u.email}</p>
+                </div>
+                <span className="text-xs text-secondary-400">{u.role}</span>
+              </button>
+            ))}
+          </div>
+        )}
+      </div>
+      <div>
+        <h3 className="text-xs font-semibold text-secondary-500 uppercase tracking-wide mb-2">Gruppen</h3>
+        {groupsLoading ? (
+          <p className="text-sm text-secondary-400">Laden...</p>
+        ) : groups.length === 0 ? (
+          <p className="text-sm text-secondary-400">Keine Gruppen</p>
+        ) : (
+          <div className="space-y-1">
+            {groups.map((g) => (
+              <div key={g.id} className="flex items-center gap-2 px-2 py-1.5 rounded-lg hover:bg-secondary-50 transition-colors">
+                <div className="w-8 h-8 rounded-full bg-secondary-200 flex items-center justify-center flex-shrink-0">
+                  <svg className="w-4 h-4 text-secondary-500" fill="none" viewBox="0 0 24 24" stroke="currentColor" aria-hidden="true">
+                    <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M17 20h5v-2a3 3 0 00-5.356-1.857M17 20H7m10 0v-2c0-.656-.126-1.283-.356-1.857M7 20H2v-2a3 3 0 015.356-1.857M7 20v-2c0-.656.126-1.283.356-1.857m0 0a5.002 5.002 0 019.288 0M15 7a3 3 0 11-6 0 3 3 0 016 0z" />
+                  </svg>
+                </div>
+                <div className="flex-1 min-w-0">
+                  <p className="text-sm font-medium text-secondary-700 truncate">{g.name}</p>
+                  {g.description && <p className="text-xs text-secondary-400 truncate">{g.description}</p>}
+                </div>
+              </div>
+            ))}
+          </div>
+        )}
+      </div>
+    </div>
+  );
+}
+
+// ─── Conversation List Item ───
+
+function ConversationListItem({
+  conv,
+  isActive,
+  onClick,
+}: {
+  conv: Conversation;
+  isActive: boolean;
+  onClick: () => void;
+}) {
+  const senderIcon =
+    conv.last_msg_sender_type === 'ai' ? '🤖' : conv.last_msg_sender_type === 'system' ? '🔔' : '👤';
+
+  return (
+    <button
+      onClick={onClick}
+      className={`flex items-start gap-2 px-3 py-2 rounded-lg transition-colors w-full text-left ${
+        isActive
+          ? 'bg-primary-100 text-primary-700'
+          : 'hover:bg-secondary-50 text-secondary-700'
+      }`}
+      data-testid={`conv-item-${conv.id}`}
+    >
+      <div className="flex-1 min-w-0">
+        <div className="flex items-center gap-1">
+          {conv.is_pinned && <span className="text-secondary-400 flex-shrink-0">📌</span>}
+          <p className="text-sm font-medium truncate flex-1">
+            {conv.title || 'Ohne Titel'}
+          </p>
+          {conv.unread_count > 0 && (
+            <span className="flex-shrink-0 w-5 h-5 bg-danger-500 text-white text-[10px] font-bold rounded-full flex items-center justify-center">
+              {conv.unread_count}
+            </span>
+          )}
+        </div>
+        {conv.last_msg_preview && (
+          <p className="text-xs text-secondary-400 truncate mt-0.5">
+            <span className="mr-1">{senderIcon}</span>
+            {conv.last_msg_preview}
+          </p>
+        )}
+      </div>
+    </button>
+  );
+}
+
+// ─── Message Feed ───
+
+function MessageFeed({
+  messages,
+  loading,
+}: {
+  messages: Message[];
+  loading: boolean;
+}) {
+  const scrollRef = useRef<HTMLDivElement>(null);
+
+  useEffect(() => {
+    if (scrollRef.current) {
+      scrollRef.current.scrollTop = scrollRef.current.scrollHeight;
+    }
+  }, [messages]);
+
+  if (loading) {
+    return (
+      <div className="flex items-center justify-center h-full text-sm text-secondary-400">
+        Laden...
+      </div>
+    );
+  }
+
+  if (messages.length === 0) {
+    return (
+      <div className="flex items-center justify-center h-full text-sm text-secondary-400">
+        Keine Nachrichten
+      </div>
+    );
+  }
+
+  return (
+    <div ref={scrollRef} className="flex-1 overflow-y-auto p-3 space-y-2">
+      {messages.map((msg) => {
+        const isAI = msg.sender_type === 'ai';
+        const isSystem = msg.sender_type === 'system';
+        const senderIcon = isAI ? '🤖' : isSystem ? '🔔' : '👤';
+        const senderName = isAI ? 'KI' : isSystem ? 'System' : 'Benutzer';
+
+        return (
+          <div
+            key={msg.id}
+            className={`flex flex-col ${msg.sender_type === 'user' ? 'items-end' : 'items-start'}`}
+          >
+            <div
+              className={`max-w-[85%] rounded-lg px-3 py-2 ${
+                msg.sender_type === 'user'
+                  ? 'bg-primary-500 text-white'
+                  : 'bg-secondary-100 text-secondary-800'
+              }`}
+            >
+              <div className="flex items-center gap-1 mb-0.5">
+                <span className="text-xs">{senderIcon}</span>
+                <span className="text-xs font-medium opacity-70">{senderName}</span>
+              </div>
+              <div className="text-sm whitespace-pre-wrap break-words">{msg.content}</div>
+              {/* Render rich content blocks via BlockRenderer */}
+              {msg.blocks && msg.blocks.length > 0 && (
+                <div className="mt-2">
+                  <BlockRenderer blocks={msg.blocks} />
+                </div>
+              )}
+              {msg.created_at && (
+                <span className="text-[10px] opacity-50 mt-0.5 block">
+                  {new Date(msg.created_at).toLocaleTimeString('de-DE', { hour: '2-digit', minute: '2-digit' })}
+                </span>
+              )}
+            </div>
+          </div>
+        );
+      })}
+    </div>
+  );
+}
+
+// ─── Message Input ───
+
+function MessageInput({
+  onSend,
+  disabled,
+}: {
+  onSend: (text: string) => void;
+  disabled: boolean;
+}) {
+  const [text, setText] = useState('');
+
+  const handleSend = () => {
+    if (!text.trim() || disabled) return;
+    onSend(text.trim());
+    setText('');
+  };
+
+  const handleKeyDown = (e: React.KeyboardEvent) => {
+    if (e.key === 'Enter' && !e.shiftKey) {
+      e.preventDefault();
+      handleSend();
+    }
+  };
+
+  return (
+    <div className="flex items-center gap-2 p-3 border-t border-secondary-200">
+      <input
+        type="text"
+        value={text}
+        onChange={(e) => setText(e.target.value)}
+        onKeyDown={handleKeyDown}
+        disabled={disabled}
+        placeholder={disabled ? 'Schreibgeschützt' : 'Nachricht eingeben...'}
+        className="flex-1 px-3 py-2 text-sm rounded-lg border border-secondary-200 bg-white text-secondary-800 placeholder-secondary-400 focus:outline-none focus:ring-2 focus:ring-primary-500 focus:border-transparent disabled:bg-secondary-50 disabled:text-secondary-400"
+        data-testid="message-input"
+      />
+      <button
+        onClick={handleSend}
+        disabled={disabled || !text.trim()}
+        className="p-2 rounded-lg bg-primary-500 text-white hover:bg-primary-600 disabled:bg-secondary-200 disabled:text-secondary-400 transition-colors min-h-touch min-w-touch flex items-center justify-center"
+        aria-label="Senden"
+        data-testid="message-send-btn"
+      >
+        {sendIcon}
+      </button>
+    </div>
+  );
+}
+
+// ─── Main MessageSidebar Component ───
+
+export function MessageSidebar() {
+  const { t } = useTranslation();
+  const {
+    messageSidebarCollapsed,
+    toggleMessageSidebar,
+  } = useUIStore();
+
+  const {
+    conversations,
+    activeConversationId,
+    messages,
+    loading,
+    setConversations,
+    setActiveConversation,
+    setMessages,
+    setLoading,
+    setUnread,
+  } = useCommStore();
+
+  const [currentView, setCurrentView] = useState<SidebarView>('conversations');
+  const [messagesLoading, setMessagesLoading] = useState(false);
+  const [error, setError] = useState<string | null>(null);
+
+  // Connect WebSocket
+  useCommWebSocket();
+
+  // Load conversations on mount
+  useEffect(() => {
+    loadConversations();
+    // eslint-disable-next-line react-hooks/exhaustive-deps
+  }, []);
+
+  const loadConversations = useCallback(async () => {
+    setLoading(true);
+    setError(null);
+    try {
+      const res = await listConversations();
+      const convs = res.items || [];
+      setConversations(convs);
+      // Auto-select first pinned conversation or first conversation
+      if (convs.length > 0 && !activeConversationId) {
+        const pinned = convs.find((c) => c.is_pinned);
+        const first = pinned || convs[0];
+        setActiveConversation(first.id);
+        loadMessages(first.id);
+      }
+    } catch (e) {
+      console.error('Failed to load conversations:', e);
+      setError('Konversationen konnten nicht geladen werden');
+    } finally {
+      setLoading(false);
+    }
+    // eslint-disable-next-line react-hooks/exhaustive-deps
+  }, []);
+
+  const loadMessages = useCallback(async (convId: string) => {
+    setMessagesLoading(true);
+    try {
+      const res = await getMessages(convId);
+      setMessages(convId, res.items || []);
+      // Mark as read
+      await markRead(convId);
+      setUnread(convId, 0);
+    } catch (e) {
+      console.error('Failed to load messages:', e);
+      setMessages(convId, []);
+    } finally {
+      setMessagesLoading(false);
+    }
+  }, []);
+
+  const handleSelectConversation = useCallback(
+    (convId: string) => {
+      setActiveConversation(convId);
+      loadMessages(convId);
+    },
+    [loadMessages],
+  );
+
+  const handleSendMessage = useCallback(
+    async (text: string) => {
+      if (!activeConversationId) return;
+      try {
+        await sendMessage(activeConversationId, {
+          content: text,
+          content_format: 'text',
+        });
+        // The message will arrive via WebSocket, but also reload to be safe
+        loadMessages(activeConversationId);
+      } catch (e) {
+        console.error('Failed to send message:', e);
+        setError('Nachricht konnte nicht gesendet werden');
+      }
+    },
+    [activeConversationId, loadMessages],
+  );
+
+  const handleStartDirectChat = useCallback(
+    async (userId: string, userName: string) => {
+      try {
+        const conv = await createConversation({
+          title: userName,
+          participant_ids: [userId],
+          is_direct: true,
+        });
+        // Reload conversations to include the new one
+        await loadConversations();
+        if (conv && conv.id) {
+          handleSelectConversation(conv.id);
+        }
+      } catch (e) {
+        console.error('Failed to start direct chat:', e);
+        setError('Direkt-Chat konnte nicht gestartet werden');
+      }
+    },
+    [loadConversations, handleSelectConversation],
+  );
+
+  // Quick access buttons (same icons as AISidebar tabs)
+  const quickAccess: QuickAccessDef[] = [
+    { key: 'assistant', label: 'Assistent', icon: robotIcon, testId: 'msg-sidebar-qa-assistant', view: 'conversations', filterPinned: 'assistant' },
+    { key: 'liveai', label: 'Live KI', icon: bulbIcon, testId: 'msg-sidebar-qa-liveai', view: 'conversations', filterPinned: 'liveai' },
+    { key: 'system', label: t('topbar.notifications'), icon: bellIcon, testId: 'msg-sidebar-qa-system', view: 'conversations', filterPinned: 'system' },
+    { key: 'team', label: 'Team', icon: teamIcon, testId: 'msg-sidebar-qa-team', view: 'team' },
+    { key: 'all', label: 'Chat', icon: chatBubbleIcon, testId: 'msg-sidebar-qa-all', view: 'conversations' },
+  ];
+
+  // Pinned conversations (system rooms)
+  const pinnedConversations = conversations.filter((c) => c.is_pinned);
+  const normalConversations = conversations.filter((c) => !c.is_pinned);
+
+  // Active conversation object
+  const activeConv = conversations.find((c) => c.id === activeConversationId) || null;
+  const activeMessages = activeConversationId ? messages[activeConversationId] || [] : [];
+  const isSystemLocked =
+    activeConv?.is_locked && activeConv?.locked_by === 'system_notif';
+
+  // Determine which pinned conv to select when a quick-access button is clicked
+  const handleQuickAccess = (qa: QuickAccessDef) => {
+    setCurrentView(qa.view);
+    if (qa.view === 'conversations' && qa.filterPinned) {
+      // Find pinned conversation matching the filter
+      const filter = qa.filterPinned;
+      const match = pinnedConversations.find((c) =>
+        c.metadata?.room_type === filter ||
+        (filter && c.title?.toLowerCase().includes(filter)),
+      );
+      if (match) {
+        handleSelectConversation(match.id);
+        return;
+      }
+    }
+    if (qa.view === 'conversations' && !qa.filterPinned) {
+      // 'all' — just show the list, select first if none active
+      if (!activeConversationId && conversations.length > 0) {
+        handleSelectConversation(conversations[0].id);
+      }
+    }
+  };
+
+  // ─── Collapsed: narrow icon strip (desktop only) ───
+  if (messageSidebarCollapsed) {
+    return (
+      <div
+        className="hidden md:flex flex-shrink-0 w-12 flex-col items-center border-l border-secondary-200 bg-white py-3 gap-2"
+        data-testid="message-sidebar-collapsed"
+      >
+        {quickAccess.map((qa) => (
+          <button
+            key={qa.key}
+            onClick={() => {
+              handleQuickAccess(qa);
+              toggleMessageSidebar();
+            }}
+            className="p-2 rounded-md hover:bg-secondary-100 min-h-touch min-w-touch flex items-center justify-center focus:outline-none focus-visible:ring-2 focus-visible:ring-primary-500 relative"
+            aria-label={qa.label}
+            title={qa.label}
+            data-testid={qa.testId}
+          >
+            {qa.icon('w-5 h-5 text-secondary-600')}
+            {qa.key === 'system' &&
+              pinnedConversations.some((c) => c.unread_count > 0) && (
+                <span className="absolute -top-0.5 -right-0.5 w-4 h-4 bg-danger-500 text-white text-[10px] font-bold rounded-full flex items-center justify-center">
+                  {pinnedConversations.reduce((sum, c) => sum + c.unread_count, 0)}
+                </span>
+              )}
+          </button>
+        ))}
+      </div>
+    );
+  }
+
+  // ─── Icon Strip (expanded) ───
+  const iconStrip = (
+    <div className="flex items-center gap-1 px-2 h-[58px] border-b border-secondary-200" role="tablist">
+      {quickAccess.map((qa) => {
+        const isActive =
+          (qa.view === 'conversations' && currentView === 'conversations') ||
+          (qa.view === 'team' && currentView === 'team');
+        return (
+          <button
+            key={qa.key}
+            onClick={() => handleQuickAccess(qa)}
+            className={`p-2 rounded-md min-h-touch min-w-touch flex items-center justify-center transition-colors relative ${
+              isActive
+                ? 'bg-primary-100 text-primary-600'
+                : 'text-secondary-500 hover:bg-secondary-100 hover:text-secondary-700'
+            }`}
+            role="tab"
+            aria-selected={isActive}
+            aria-label={qa.label}
+            data-testid={qa.testId}
+          >
+            {qa.icon('w-5 h-5')}
+            {qa.key === 'system' &&
+              pinnedConversations.some((c) => c.unread_count > 0) && (
+                <span className="absolute -top-0.5 -right-0.5 w-4 h-4 bg-danger-500 text-white text-[10px] font-bold rounded-full flex items-center justify-center">
+                  {pinnedConversations.reduce((sum, c) => sum + c.unread_count, 0)}
+                </span>
+              )}
+          </button>
+        );
+      })}
+      <div className="flex-1" />
+      <button
+        onClick={toggleMessageSidebar}
+        className="p-1.5 rounded-md text-secondary-400 hover:text-secondary-600 hover:bg-secondary-100 min-h-touch min-w-touch flex items-center justify-center"
+        title="Einklappen"
+        aria-label="Messaging einklappen"
+      >
+        {chevronRightIcon}
+      </button>
+    </div>
+  );
+
+  // ─── Conversation List Panel ───
+  const renderConversationList = () => (
+    <div className="flex flex-col h-full overflow-y-auto p-2 gap-1" data-testid="conversation-list">
+      {loading && (
+        <p className="text-sm text-secondary-400 text-center py-4">Laden...</p>
+      )}
+      {error && (
+        <p className="text-sm text-red-500 text-center py-2">{error}</p>
+      )}
+      {!loading && conversations.length === 0 && !error && (
+        <p className="text-sm text-secondary-400 text-center py-4">Keine Konversationen</p>
+      )}
+      {/* Pinned conversations */}
+      {pinnedConversations.length > 0 && (
+        <>
+          <h3 className="text-xs font-semibold text-secondary-500 uppercase tracking-wide px-1 py-1 flex items-center gap-1">
+            {pinIcon} Angespinnt
+          </h3>
+          {pinnedConversations.map((conv) => (
+            <ConversationListItem
+              key={conv.id}
+              conv={conv}
+              isActive={conv.id === activeConversationId}
+              onClick={() => handleSelectConversation(conv.id)}
+            />
+          ))}
+        </>
+      )}
+      {/* Normal conversations */}
+      {normalConversations.length > 0 && (
+        <>
+          <h3 className="text-xs font-semibold text-secondary-500 uppercase tracking-wide px-1 py-1">
+            Konversationen
+          </h3>
+          {normalConversations.map((conv) => (
+            <ConversationListItem
+              key={conv.id}
+              conv={conv}
+              isActive={conv.id === activeConversationId}
+              onClick={() => handleSelectConversation(conv.id)}
+            />
+          ))}
+        </>
+      )}
+    </div>
+  );
+
+  // ─── Main Content Area ───
+  const renderContent = () => {
+    if (currentView === 'team') {
+      return <TeamPanel onStartDirectChat={handleStartDirectChat} />;
+    }
+    // conversations view: show conversation list + message feed + input
+    return (
+      <div className="flex flex-col h-full">
+        {/* Conversation list (narrow, top section within panel) */}
+        <div className="border-b border-secondary-200 max-h-[40%] overflow-y-auto">
+          {renderConversationList()}
+        </div>
+        {/* Message feed */}
+        <div className="flex-1 overflow-hidden flex flex-col">
+          {activeConv && (
+            <div className="px-3 py-2 border-b border-secondary-200 flex items-center gap-2">
+              {activeConv.is_pinned && <span className="text-secondary-400">📌</span>}
+              <span className="text-sm font-medium text-secondary-700 truncate">
+                {activeConv.title || 'Ohne Titel'}
+              </span>
+            </div>
+          )}
+          <MessageFeed messages={activeMessages} loading={messagesLoading} />
+          {/* Message input (hidden for system-locked conversations) */}
+          {activeConv && !isSystemLocked && (
+            <MessageInput onSend={handleSendMessage} disabled={false} />
+          )}
+          {isSystemLocked && (
+            <div className="p-3 border-t border-secondary-200 text-center">
+              <span className="text-xs text-secondary-400">System-Konversation (schreibgeschützt)</span>
+            </div>
+          )}
+        </div>
+      </div>
+    );
+  };
+
+  // ─── Expanded: Mobile = full width overlay, Desktop = resizable panel ───
+  return (
+    <>
+      {/* Mobile: full width overlay with back button */}
+      <div
+        className="md:hidden fixed inset-0 z-50 bg-white flex flex-col"
+        data-testid="message-sidebar-mobile"
+      >
+        <div className="h-14 flex items-center gap-2 px-3 border-b border-secondary-200">
+          <button
+            onClick={toggleMessageSidebar}
+            className="inline-flex items-center gap-1 px-2 py-1 rounded text-sm text-secondary-700 hover:bg-secondary-100 min-h-touch"
+            aria-label="Zurück"
+            data-testid="message-sidebar-back"
+          >
+            <svg className="w-5 h-5" fill="none" viewBox="0 0 24 24" stroke="currentColor" aria-hidden="true">
+              <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M15 19l-7-7 7-7" />
+            </svg>
+            <span className="text-sm font-medium">Zurück</span>
+          </button>
+        </div>
+        {iconStrip}
+        <div className="flex-1 overflow-hidden">{renderContent()}</div>
+      </div>
+
+      {/* Desktop: resizable panel */}
+      <ResizablePanel
+        initialWidth={320}
+        minWidth={240}
+        maxWidth={600}
+        handleSide="left"
+        className="hidden md:flex border-l border-secondary-200 bg-white"
+        data-testid="message-sidebar-pane"
+      >
+        <div className="h-full flex flex-col">
+          {iconStrip}
+          <div className="flex-1 overflow-hidden">{renderContent()}</div>
+        </div>
+      </ResizablePanel>
+    </>
+  );
+}

frontend/src/components/layout/TopBar.tsx

@@ -14,7 +14,7 @@ export function TopBar() {
   const navigate = useNavigate();
   const { user, currentTenant } = useAuthStore();
   const tenants = user?.tenants || [];
-  const { toggleSidebar, openAISidebarProactive } = useUIStore();
+  const { toggleSidebar, toggleMessageSidebar } = useUIStore();
   const logoutMutation = useLogout();
 
   const [userMenuOpen, setUserMenuOpen] = useState(false);

frontend/src/hooks/useCommWebSocket.ts

@@ -0,0 +1,140 @@
+import { useEffect, useRef } from 'react';
+import { useCommStore } from '@/store/commStore';
+import type { Conversation, Message } from '@/store/commStore';
+
+/**
+ * useCommWebSocket — manages a WebSocket connection to /api/v1/comm/ws.
+ *
+ * Handles real-time events: new messages, conversation updates, typing
+ * indicators, and streaming tokens. Auto-reconnects with exponential backoff.
+ */
+export function useCommWebSocket() {
+  const wsRef = useRef<WebSocket | null>(null);
+  const reconnectTimeout = useRef<number | undefined>(undefined);
+  const addMessage = useCommStore((s) => s.addMessage);
+  const updateConversation = useCommStore((s) => s.updateConversation);
+  const setTyping = useCommStore((s) => s.setTyping);
+  const activeConversationId = useCommStore((s) => s.activeConversationId);
+  const setMessages = useCommStore((s) => s.setMessages);
+
+  useEffect(() => {
+    let reconnectAttempts = 0;
+    const maxReconnectDelay = 30000;
+
+    function connect() {
+      const protocol = window.location.protocol === 'https:' ? 'wss:' : 'ws:';
+      const ws = new WebSocket(`${protocol}//${window.location.host}/api/v1/comm/ws`);
+      wsRef.current = ws;
+
+      ws.onopen = () => {
+        reconnectAttempts = 0;
+        console.log('Comm WebSocket connected');
+      };
+
+      ws.onmessage = (event) => {
+        try {
+          const data = JSON.parse(event.data);
+          switch (data.type) {
+            case 'message.new': {
+              if (data.message && data.conversation_id) {
+                addMessage(data.conversation_id, data.message as Message);
+              }
+              break;
+            }
+            case 'conversation.updated': {
+              if (data.conversation) {
+                updateConversation(data.conversation as Conversation);
+              }
+              break;
+            }
+            case 'message.streaming': {
+              // Update last message content with streaming token
+              if (data.conversation_id && data.token) {
+                const msgs = useCommStore.getState().messages[data.conversation_id] || [];
+                if (msgs.length > 0) {
+                  const lastMsg = msgs[msgs.length - 1];
+                  const updatedMsg = {
+                    ...lastMsg,
+                    content: lastMsg.content + data.token,
+                  };
+                  setMessages(data.conversation_id, [...msgs.slice(0, -1), updatedMsg]);
+                }
+              }
+              break;
+            }
+            case 'message.streaming.done': {
+              // Replace streaming content with final message
+              if (data.conversation_id && data.message) {
+                const msgs = useCommStore.getState().messages[data.conversation_id] || [];
+                if (msgs.length > 0) {
+                  setMessages(data.conversation_id, [...msgs.slice(0, -1), data.message as Message]);
+                }
+              }
+              break;
+            }
+            case 'typing': {
+              if (data.conversation_id) {
+                const currentTyping = useCommStore.getState().typingUsers[data.conversation_id] || [];
+                if (data.is_typing) {
+                  if (!currentTyping.includes(data.user_id)) {
+                    setTyping(data.conversation_id, [...currentTyping, data.user_id]);
+                  }
+                } else {
+                  setTyping(
+                    data.conversation_id,
+                    currentTyping.filter((uid) => uid !== data.user_id),
+                  );
+                }
+              }
+              break;
+            }
+            case 'pong':
+              break;
+            default:
+              break;
+          }
+        } catch (err) {
+          console.error('Comm WebSocket message parse error:', err);
+        }
+      };
+
+      ws.onclose = () => {
+        console.log('Comm WebSocket disconnected');
+        const delay = Math.min(1000 * Math.pow(2, reconnectAttempts), maxReconnectDelay);
+        reconnectAttempts++;
+        reconnectTimeout.current = window.setTimeout(connect, delay);
+      };
+
+      ws.onerror = (error) => {
+        console.error('Comm WebSocket error:', error);
+      };
+    }
+
+    connect();
+
+    // Ping interval to keep connection alive
+    const pingInterval = setInterval(() => {
+      if (wsRef.current?.readyState === WebSocket.OPEN) {
+        wsRef.current.send(JSON.stringify({ type: 'ping' }));
+      }
+    }, 30000);
+
+    return () => {
+      clearInterval(pingInterval);
+      if (reconnectTimeout.current) clearTimeout(reconnectTimeout.current);
+      wsRef.current?.close();
+    };
+    // eslint-disable-next-line react-hooks/exhaustive-deps
+  }, []);
+
+  // Subscribe to active conversation when it changes
+  useEffect(() => {
+    if (wsRef.current?.readyState === WebSocket.OPEN && activeConversationId) {
+      wsRef.current.send(
+        JSON.stringify({ type: 'subscribe', conversation_id: activeConversationId }),
+      );
+    }
+  }, [activeConversationId]);
+
+  return wsRef;
+}

frontend/src/store/commStore.ts

@@ -0,0 +1,107 @@
+import { create } from 'zustand';
+
+export interface Participant {
+  id: string;
+  conversation_id: string;
+  participant_id: string | null;
+  participant_type: string;
+  display_name: string | null;
+  role: string;
+}
+
+export interface Conversation {
+  id: string;
+  title: string | null;
+  is_locked: boolean;
+  locked_by: string | null;
+  is_direct: boolean;
+  is_archived: boolean;
+  is_pinned: boolean;
+  created_by: string | null;
+  created_by_type: string;
+  last_msg_at: string | null;
+  last_msg_preview: string | null;
+  last_msg_sender_type: string | null;
+  participants: Participant[];
+  unread_count: number;
+  metadata: Record<string, any>;
+}
+
+export interface MessageBlock {
+  id: string;
+  block_type: string;
+  block_data: Record<string, any>;
+  sort_order: number;
+}
+
+export interface MessageAttachment {
+  id: string;
+  file_id: string | null;
+  file_source: string;
+  file_name: string;
+  file_type: string;
+  file_size: number | null;
+  thumbnail_path: string | null;
+}
+
+export interface Message {
+  id: string;
+  conversation_id: string;
+  sender_id: string | null;
+  sender_type: string;
+  content: string;
+  content_format: string;
+  metadata: Record<string, any>;
+  reply_to_id: string | null;
+  is_pinned: boolean;
+  created_at: string | null;
+  edited_at: string | null;
+  blocks: MessageBlock[];
+  attachments: MessageAttachment[];
+  reactions: any[];
+}
+
+export interface CommState {
+  conversations: Conversation[];
+  activeConversationId: string | null;
+  messages: Record<string, Message[]>;
+  typingUsers: Record<string, string[]>;
+  unreadCounts: Record<string, number>;
+  loading: boolean;
+
+  setConversations: (convs: Conversation[]) => void;
+  setActiveConversation: (id: string | null) => void;
+  addMessage: (convId: string, msg: Message) => void;
+  setMessages: (convId: string, msgs: Message[]) => void;
+  updateConversation: (conv: Conversation) => void;
+  setTyping: (convId: string, userIds: string[]) => void;
+  setUnread: (convId: string, count: number) => void;
+  setLoading: (loading: boolean) => void;
+}
+
+export const useCommStore = create<CommState>((set) => ({
+  conversations: [],
+  activeConversationId: null,
+  messages: {},
+  typingUsers: {},
+  unreadCounts: {},
+  loading: false,
+  setConversations: (conversations) => set({ conversations }),
+  setActiveConversation: (activeConversationId) => set({ activeConversationId }),
+  addMessage: (convId, msg) => set((s) => ({
+    messages: { ...s.messages, [convId]: [...(s.messages[convId] || []), msg] },
+  })),
+  setMessages: (convId, msgs) => set((s) => ({
+    messages: { ...s.messages, [convId]: msgs },
+  })),
+  updateConversation: (conv) => set((s) => ({
+    conversations: s.conversations.map((c) => (c.id === conv.id ? conv : c)),
+  })),
+  setTyping: (convId, userIds) => set((s) => ({
+    typingUsers: { ...s.typingUsers, [convId]: userIds },
+  })),
+  setUnread: (convId, count) => set((s) => ({
+    unreadCounts: { ...s.unreadCounts, [convId]: count },
+  })),
+  setLoading: (loading) => set({ loading }),
+}));

frontend/src/store/uiStore.ts

@@ -18,6 +18,7 @@ export interface UIState {
   suggestionSidebarOpen: boolean;
   aiSidebarCollapsed: boolean;
   aiSidebarTab: AISidebarTab;
+  messageSidebarCollapsed: boolean;
   toasts: Toast[];
   notifications: string[];
   setTheme: (theme: Theme) => void;
@@ -29,6 +30,8 @@ export interface UIState {
   setAISidebarCollapsed: (collapsed: boolean) => void;
   setAISidebarTab: (tab: AISidebarTab) => void;
   openAISidebarProactive: () => void;
+  toggleMessageSidebar: () => void;
+  setMessageSidebarCollapsed: (collapsed: boolean) => void;
   addToast: (toast: Omit<Toast, 'id'>) => void;
   removeToast: (id: string) => void;
   clearToasts: () => void;
@@ -45,12 +48,9 @@ export const useUIStore = create<UIState>((set) => ({
   suggestionSidebarOpen: false,
   aiSidebarCollapsed: true,
   aiSidebarTab: 'chat',
+  messageSidebarCollapsed: true,
   toasts: [],
-  notifications: [
+  notifications: [],
-    'Neuer Kontakt hinzugefügt: Max Mustermann',
-    'Firma aktualisiert: TechCorp GmbH',
-    'Meeting um 14:00 Uhr mit Müller AG',
-  ],
   setTheme: (theme) => {
     localStorage.setItem('leocrm_theme', theme);
     set({ theme });
@@ -66,6 +66,8 @@ export const useUIStore = create<UIState>((set) => ({
   setAISidebarCollapsed: (collapsed) => set({ aiSidebarCollapsed: collapsed }),
   setAISidebarTab: (tab) => set({ aiSidebarTab: tab }),
   openAISidebarProactive: () => set({ aiSidebarCollapsed: false, aiSidebarTab: 'proactive' }),
+  toggleMessageSidebar: () => set((s) => ({ messageSidebarCollapsed: !s.messageSidebarCollapsed })),
+  setMessageSidebarCollapsed: (collapsed) => set({ messageSidebarCollapsed: collapsed }),
   addToast: (toast) => {
     const id = `toast-${++toastIdCounter}`;
     set((s) => ({ toasts: [...s.toasts, { ...toast, id }] }));

frontend/test_report.md

@@ -1,110 +1,44 @@
-# Test Report — T08c: Frontend Mail UI + Global Search UI
+# Test Report — Phase 4: Unified Messaging Frontend
 
-## Date: 2026-07-01
+## Task
+Implement MessageSidebar replacing AISidebar with comm API backend integration.
 
-## Test Execution
+## Files Created/Modified
+
+### New Files
+1. `src/store/commStore.ts` — Zustand store for conversations, messages, typing, unread counts
+2. `src/api/comm.ts` — API client covering all `/api/v1/comm/*` endpoints (conversations, messages, reactions, read state, mini-apps, block types)
+3. `src/hooks/useCommWebSocket.ts` — WebSocket hook with auto-reconnect, ping, streaming, typing indicators
+4. `src/components/layout/MessageSidebar.tsx` — Main sidebar component (716 lines) replicating AISidebar design exactly
+
+### Modified Files
+5. `src/store/uiStore.ts` — Added `messageSidebarCollapsed` + `toggleMessageSidebar`; replaced mock notifications with empty array; kept `aiSidebarCollapsed` for backward compat
+6. `src/components/layout/AppShell.tsx` — Replaced `AISidebar` import with `MessageSidebar`
+7. `src/components/layout/TopBar.tsx` — Replaced `openAISidebarProactive` with `toggleMessageSidebar`
+
+## TypeScript Compilation
+
+Command: `npx tsc --noEmit`
 
-### Command
 ```
-cd /a0/usr/workdir/dev-projects/leocrm/frontend && npx vitest run src/__tests__/mail/ src/__tests__/search/ --reporter=verbose
+src/pages/Dms.tsx(553,13): error TS2322: ... onRangeSelect does not exist on type FileExplorerProps
+src/pages/Dms.tsx(647,15): error TS2322: ... onRangeSelect does not exist on type FileExplorerProps
 ```
 
-### Results
+**Result:** All new/modified files compile cleanly. Only 2 pre-existing errors in `Dms.tsx` (unrelated to this task — `onRangeSelect` prop missing on `FileExplorerProps` type).
-- **Test Files**: 5 passed (5)
-- **Tests**: 44 passed (44)
-- **Duration**: ~6s
 
-### Test Breakdown
+## Smoke Test Description
 
-#### MailPage.test.tsx (14 tests)
+- **Build:** `npx tsc --noEmit` exits with only pre-existing Dms.tsx errors (0 new errors from this task)
-- ✓ renders mail page after loading
+- **Design fidelity:** MessageSidebar uses identical icons (robotIcon, bellIcon, bulbIcon, teamIcon, chatBubbleIcon), identical ResizablePanel (320px initial, 240-600 range, handleSide=left), identical mobile/desktop structure (collapsed icon strip → expanded resizable panel + mobile overlay)
-- ✓ renders folder tree pane
+- **API integration:** comm.ts uses same `apiGet/apiPost/apiPatch/apiDelete` from `client.ts` as `ai.ts` — consistent with existing conventions
-- ✓ renders mail list pane
+- **WebSocket:** Auto-reconnect with exponential backoff, ping interval, handles message.new, conversation.updated, message.streaming, typing events
-- ✓ renders mail detail pane
+- **Store:** commStore provides conversations, messages per conversation, typing users, unread counts with all setter methods
-- ✓ renders compose button
+- **uiStore:** messageSidebarCollapsed defaults to true (same as aiSidebarCollapsed), toggleMessageSidebar works, mock notifications replaced with empty array
-- ✓ renders shared mailbox selector
-- ✓ renders mail search bar
-- ✓ renders folders after loading (INBOX, Sent)
-- ✓ renders mails after loading (Test Subject, Another Subject)
-- ✓ shows compose modal when compose button is clicked
-- ✓ shows compose toolbar with bold and italic buttons
-- ✓ renders mail detail empty state initially
-- ✓ renders mail detail when mail is clicked
-- ✓ shows reply and forward buttons in mail detail
 
-#### ComposeModal.test.tsx (10 tests)
+## What Was NOT Tested
-- ✓ renders compose modal when open
-- ✓ renders compose toolbar with bold button
-- ✓ renders recipient input field
-- ✓ renders subject input field
-- ✓ renders editor
-- ✓ renders send button
-- ✓ renders template picker toggle button
-- ✓ shows template picker when template button is clicked
-- ✓ pre-fills reply fields when mode is reply
-- ✓ pre-fills forward fields when mode is forward
 
-#### MailSettings.test.tsx (9 tests)
+- Live API calls (requires running backend with kommunikation plugin)
-- ✓ renders settings page
+- WebSocket connection (requires authenticated session)
-- ✓ renders accounts tab content
+- Visual rendering (requires dev server + browser)
-- ✓ renders add account button
+- These require runtime verification in a subsequent phase
-- ✓ shows add account form when button is clicked
-- ✓ renders signature manager in signatures tab
-- ✓ renders rule editor in rules tab
-- ✓ renders label manager in labels tab
-- ✓ renders vacation responder in vacation tab
-- ✓ renders PGP settings in PGP tab
-- ✓ renders account list with test connection button
-
-#### GlobalSearchTabs.test.tsx (8 tests)
-- ✓ renders search page
-- ✓ renders search input field
-- ✓ renders search tabs after results load
-- ✓ renders all results in the all tab
-- ✓ renders company results
-- ✓ renders all 5 result types in the all tab
-- ✓ renders search submit button
-- ✓ shows query display
-
-#### GlobalSearch.test.tsx (2 tests — pre-existing, still passing)
-- ✓ renders search page
-- ✓ renders search input field
-
-## Type Check
-```
-npx tsc --noEmit
-```
-Result: **PASS** — zero errors
-
-## Build
-```
-npx vite build
-```
-Result: **PASS** — built in ~6s, 267 modules transformed
-
-## Smoke Test
-- Mail page renders with three-pane layout (folder tree + mail list + reading pane)
-- Compose modal opens with toolbar (bold, italic, link, template insert)
-- Reply pre-fills recipient and subject with Re: prefix
-- Forward pre-fills subject with Fwd: prefix
-- Mail settings page shows tabs: Accounts, Signatures, Rules, Labels, Vacation, PGP
-- Global search results page shows tabs: All, Companies, Contacts, Mails, Files, Events
-- Search dropdown in TopBar already existed (SearchDropdown component)
-
-## Acceptance Criteria Coverage
-- AC2: Mail route /mail renders folder tree + mail list + reading pane ✓
-- AC3: Click folder → mail list updates ✓
-- AC4: Click mail → detail with sanitized HTML body + attachments ✓
-- AC5: Compose button → editor with toolbar (bold, italic, link, template insert) ✓
-- AC6: Reply/forward buttons → compose pre-filled ✓
-- AC7: Template picker dropdown in compose → inserts template body ✓
-- AC8: Signature manager in settings → create/edit/delete signatures ✓
-- AC9: Rule editor → condition builder + action selector ✓
-- AC10: Label manager → create labels with colors ✓
-- AC11: PGP settings → import private key, view contact public keys ✓
-- AC12: Vacation responder toggle → date range + auto-reply text ✓
-- AC13: Shared mailbox selector → switch between personal+shared accounts ✓
-- AC14: Attachment download → file stream downloaded ✓
-- AC15: Create event from mail → calendar event modal pre-filled ✓
-- AC16: Global search results page → tabs for companies/contacts/mails/files/events ✓
-- AC17: Global search autocomplete in TopBar → dropdown with suggestions ✓ (existing SearchDropdown component)