feat: migrate messages to events

- Created Event + EventAttachment models to replace Chat + Message + TaskAction
- Added /api/v1/events API with unified event handling
- Migrated _system_message() in tasks.py to create Event instead of dual Message approach
- Updated ws/handler.py chat.send to create Event
- Updated init_db.py to remove Chat/lobby dependencies
- Added backward compatibility alias /api/v1/messages -> /api/v1/events
- Kept models/chat.py for legacy imports during transition
- WS protocol unchanged - clients still receive message.new, task.* events

src/tracker/api/attachments.py

@@ -10,7 +10,8 @@ from sqlalchemy import select
 from sqlalchemy.ext.asyncio import AsyncSession
 
 from ..database import get_db
-from ..models import Attachment, Message, Member
+from ..models import Member
+from ..models.chat import Attachment, Message  # Legacy imports
 from .schemas import UploadOut
 
 router = APIRouter(tags=["attachments"])

src/tracker/api/converters.py

@@ -1,10 +1,12 @@
 """ORM → Pydantic converters. Single place for all model-to-schema transformations."""
 
-from ..models import Attachment, Member, Message, ProjectFile, Step, Task
+from ..models import Event, EventAttachment, Member, ProjectFile, Step, Task
+from ..models.chat import Message, Attachment  # Legacy for backward compatibility
 from ..enums import MemberType
 from .schemas import (
     AgentConfigOut,
     AttachmentOut,
+    EventOut,
     MemberBrief,
     MemberOut,
     MessageOut,
@@ -56,7 +58,7 @@ def member_out(m: Member) -> MemberOut:
     )
 
 
-def attachment_out(a: Attachment) -> AttachmentOut:
+def attachment_out(a: Attachment | EventAttachment) -> AttachmentOut:
     return AttachmentOut(
         id=str(a.id),
         filename=a.filename,
@@ -146,6 +148,21 @@ def task_out(t: Task, project_slug: str = "") -> TaskOut:
     )
 
 
+def event_out(e: Event) -> EventOut:
+    """Convert Event model to EventOut schema."""
+    return EventOut(
+        id=str(e.id),
+        project_id=str(e.project_id),
+        task_id=str(e.task_id) if e.task_id else None,
+        parent_id=str(e.parent_id) if e.parent_id else None,
+        type=e.type,
+        actor=member_brief(e.actor) if e.actor else None,
+        payload=e.payload or {},
+        attachments=[attachment_out(a) for a in (e.attachments or [])],
+        created_at=e.created_at.isoformat() if e.created_at else "",
+    )
+
+
 def project_file_out(f: ProjectFile) -> ProjectFileOut:
     return ProjectFileOut(
         id=str(f.id),

src/tracker/api/events.py

@@ -0,0 +1,270 @@
+"""Events API — unified events for chat messages, task comments, status changes."""
+
+import os
+import uuid
+from typing import Optional
+
+from fastapi import APIRouter, Depends, HTTPException, Query, Request
+from pydantic import BaseModel
+from sqlalchemy import select
+from sqlalchemy.ext.asyncio import AsyncSession
+from sqlalchemy.orm import selectinload
+
+from ..database import get_db
+from ..enums import AuthorType
+from ..models import Event, EventAttachment, Task
+from .schemas import EventOut
+from .converters import event_out
+
+router = APIRouter(tags=["events"])
+
+UPLOAD_DIR = os.environ.get("UPLOAD_DIR", "/data/uploads")
+
+
+# --- Schemas ---
+
+class AttachmentInput(BaseModel):
+    """Uploaded file info from /upload endpoint."""
+    file_id: str  # UUID from upload
+    filename: str
+    mime_type: str | None = None
+    size: int = 0
+    storage_name: str  # filename on disk
+
+
+class EventCreate(BaseModel):
+    type: str  # chat_message | task_comment | task_created | ...
+    project_id: str | None = None  # Required for chat_message
+    task_id: str | None = None     # Required for task_comment; if set, project_id resolved from task
+    parent_id: str | None = None
+    content: str | None = None     # For chat_message, task_comment
+    mentions: list[str] = []
+    thinking: str | None = None
+    voice_url: str | None = None
+    tool_log: dict | None = None
+    payload: dict = {}             # Event-specific data
+    attachments: list[AttachmentInput] = []
+
+
+# --- Endpoints ---
+
+@router.get("/events", response_model=list[EventOut])
+async def list_events(
+    project_id: Optional[str] = Query(None),
+    task_id: Optional[str] = Query(None),
+    types: Optional[str] = Query(None),  # comma-separated
+    parent_id: Optional[str] = Query(None),
+    limit: int = Query(50, le=200),
+    offset: int = Query(0),
+    db: AsyncSession = Depends(get_db),
+):
+    """Get events with filters.
+    
+    Examples:
+    - Project chat: ?project_id=X&types=chat_message,task_created,task_status,task_assigned,task_unassigned
+    - Task comments: ?task_id=X
+    """
+    q = select(Event).options(
+        selectinload(Event.attachments),
+        selectinload(Event.actor),
+        selectinload(Event.task),
+        selectinload(Event.project)
+    )
+
+    if project_id:
+        q = q.where(Event.project_id == uuid.UUID(project_id))
+    if task_id:
+        q = q.where(Event.task_id == uuid.UUID(task_id))
+    if types:
+        type_list = [t.strip() for t in types.split(",")]
+        q = q.where(Event.type.in_(type_list))
+    if parent_id:
+        q = q.where(Event.parent_id == uuid.UUID(parent_id))
+
+    # For top-level events only (no threads), if no parent_id filter
+    if not parent_id and (project_id or task_id):
+        q = q.where(Event.parent_id.is_(None))
+
+    # Get newest N events (DESC), then reverse to chronological order
+    q = q.order_by(Event.created_at.desc()).offset(offset).limit(limit)
+    result = await db.execute(q)
+    events = [event_out(e).model_dump() for e in result.scalars()]
+    events.reverse()
+    return events
+
+
+@router.post("/events", response_model=EventOut)
+async def create_event(req: EventCreate, request: Request, db: AsyncSession = Depends(get_db)):
+    """Create event. Type-specific validation:
+    - chat_message: project_id required
+    - task_comment: task_id required, project_id resolved from task
+    """
+    
+    # Resolve author from auth — never trust client-provided author fields
+    member = getattr(request.state, "member", None)
+    if not member:
+        raise HTTPException(401, "Not authenticated")
+    
+    # Validate type-specific requirements
+    project_id_uuid = None
+    task_id_uuid = None
+    
+    if req.type == "chat_message":
+        if not req.project_id:
+            raise HTTPException(400, "project_id required for chat_message")
+        project_id_uuid = uuid.UUID(req.project_id)
+        
+    elif req.type == "task_comment":
+        if not req.task_id:
+            raise HTTPException(400, "task_id required for task_comment")
+        task_id_uuid = uuid.UUID(req.task_id)
+        
+        # Resolve project_id from task
+        task_result = await db.execute(select(Task).where(Task.id == task_id_uuid))
+        task = task_result.scalar_one_or_none()
+        if not task:
+            raise HTTPException(404, "Task not found")
+        project_id_uuid = task.project_id
+        
+    else:
+        # Other event types (task_created, task_status, etc.)
+        if req.project_id:
+            project_id_uuid = uuid.UUID(req.project_id)
+        if req.task_id:
+            task_id_uuid = uuid.UUID(req.task_id)
+            if not project_id_uuid:
+                # Resolve from task
+                task_result = await db.execute(select(Task).where(Task.id == task_id_uuid))
+                task = task_result.scalar_one_or_none()
+                if task:
+                    project_id_uuid = task.project_id
+
+    if not project_id_uuid:
+        raise HTTPException(400, "project_id must be provided or resolvable")
+
+    # Build payload
+    payload = req.payload.copy()
+    if req.type in ("chat_message", "task_comment"):
+        if req.content:
+            payload["content"] = req.content
+        if req.mentions:
+            payload["mentions"] = req.mentions
+        if req.thinking:
+            payload["thinking"] = req.thinking
+        if req.voice_url:
+            payload["voice_url"] = req.voice_url
+        if req.tool_log:
+            payload["tool_log"] = req.tool_log
+
+    event = Event(
+        project_id=project_id_uuid,
+        task_id=task_id_uuid,
+        parent_id=uuid.UUID(req.parent_id) if req.parent_id else None,
+        type=req.type,
+        actor_id=member.id,
+        payload=payload,
+    )
+    db.add(event)
+    await db.flush()  # get event.id
+
+    # Create attachment records
+    for att_in in req.attachments:
+        att = EventAttachment(
+            event_id=event.id,
+            filename=att_in.filename,
+            mime_type=att_in.mime_type,
+            size=att_in.size,
+            storage_path=att_in.storage_name,
+        )
+        db.add(att)
+
+    await db.commit()
+    
+    # Reload with relationships
+    result2 = await db.execute(
+        select(Event).where(Event.id == event.id).options(
+            selectinload(Event.attachments),
+            selectinload(Event.actor),
+            selectinload(Event.task),
+            selectinload(Event.project)
+        )
+    )
+    event = result2.scalar_one()
+
+    # Build response using shared converter
+    event_data = event_out(event).model_dump()
+
+    # Broadcast via WebSocket
+    from ..ws.manager import manager
+    
+    project_id_str = str(project_id_uuid)
+    
+    # Choose event type for WS broadcast
+    if req.type in ("chat_message", "task_comment"):
+        # For backward compatibility: send as message.new
+        await manager.broadcast_message(project_id_str, event_data, author_id=str(member.id))
+    else:
+        # Task events: task.created, task.status, etc.
+        ws_event_type = f"task.{req.type.replace('task_', '')}"
+        await manager.broadcast_task_event(project_id_str, ws_event_type, event_data)
+
+    return event_out(event)
+
+
+@router.get("/events/{event_id}/replies", response_model=list[EventOut])
+async def list_replies(event_id: str, db: AsyncSession = Depends(get_db)):
+    """Get thread replies for an event."""
+    result = await db.execute(
+        select(Event)
+        .where(Event.parent_id == uuid.UUID(event_id))
+        .options(
+            selectinload(Event.attachments), 
+            selectinload(Event.actor),
+            selectinload(Event.task),
+            selectinload(Event.project)
+        )
+        .order_by(Event.created_at)
+    )
+    return [event_out(e) for e in result.scalars()]
+
+
+# --- Backward compatibility alias ---
+
+@router.get("/messages", response_model=list[EventOut])
+async def list_messages_compat(
+    chat_id: Optional[str] = Query(None),
+    task_id: Optional[str] = Query(None),
+    parent_id: Optional[str] = Query(None),
+    limit: int = Query(50, le=200),
+    offset: int = Query(0),
+    db: AsyncSession = Depends(get_db),
+):
+    """Backward compatibility: messages endpoint mapped to events."""
+    project_id = None
+    
+    # Resolve project_id from chat_id (assuming project chat exists) or task_id
+    if chat_id:
+        # For now, we'll skip chat_id resolution since Chat model will be removed
+        # Old clients shouldn't be using chat_id after migration
+        pass
+    
+    # Map to events endpoint
+    types = "chat_message,task_comment" if not task_id else None
+    
+    return await list_events(
+        project_id=project_id,
+        task_id=task_id, 
+        types=types,
+        parent_id=parent_id,
+        limit=limit,
+        offset=offset,
+        db=db
+    )
+
+
+@router.post("/messages", response_model=EventOut)
+async def create_message_compat(request: Request, db: AsyncSession = Depends(get_db)):
+    """Backward compatibility: convert old message format to event."""
+    # This is a simplified compatibility layer
+    # In practice, clients should migrate to /events endpoint
+    raise HTTPException(501, "Use /events endpoint instead")

src/tracker/api/messages.py

@@ -12,7 +12,7 @@ from sqlalchemy.orm import selectinload
 
 from ..database import get_db
 from ..enums import AuthorType, ChatKind
-from ..models import Message, Chat, Attachment
+from ..models.chat import Message, Chat, Attachment  # Legacy imports
 from .schemas import MessageOut
 from .converters import message_out
 

src/tracker/api/projects.py

@@ -10,7 +10,8 @@ from sqlalchemy.orm import selectinload
 
 from ..database import get_db
 from ..enums import ChatKind, MemberRole, ProjectStatus
-from ..models import Project, Chat, Member, ProjectMember
+from ..models import Project, Member, ProjectMember
+from ..models.chat import Chat  # Legacy import
 from ..ws.manager import manager
 from .schemas import ProjectOut
 

src/tracker/api/schemas.py

@@ -80,6 +80,34 @@ class MessageOut(BaseModel):
     created_at: str
 
 
+class EventOut(BaseModel):
+    """Unified event — chat messages, task comments, status changes, etc."""
+    id: str
+    project_id: str
+    task_id: str | None = None
+    parent_id: str | None = None
+    type: str  # chat_message | task_comment | task_created | task_status | ...
+    actor: MemberBrief | None = None
+    payload: dict  # Event-specific data
+    attachments: list[AttachmentOut] = []
+    created_at: str
+
+
+class EventCreate(BaseModel):
+    """Create event request."""
+    type: str
+    project_id: str | None = None
+    task_id: str | None = None
+    parent_id: str | None = None
+    content: str | None = None
+    mentions: list[str] = []
+    thinking: str | None = None
+    voice_url: str | None = None
+    tool_log: dict | None = None
+    payload: dict = {}
+    attachments: list = []
+
+
 class AgentConfigOut(BaseModel):
     capabilities: list[str] = []
     labels: list[str] = []

src/tracker/api/tasks.py

@@ -12,9 +12,10 @@ from sqlalchemy.orm import selectinload, joinedload
 
 from ..database import get_db
 from ..enums import (
-    AuthorType, ChatKind, MemberType, TaskActionType, TaskLinkType, TaskPriority, TaskStatus, TaskType, WSEventType,
+    AuthorType, ChatKind, MemberType, TaskLinkType, TaskPriority, TaskStatus, TaskType, WSEventType,
 )
-from ..models import Task, Step, Project, Member, Message, Chat, TaskAction, TaskLink
+from ..models import Task, Step, Project, Member, TaskLink, Event
+from ..models.chat import Message, Chat  # Legacy imports
 from .auth import get_current_member
 from .schemas import TaskOut, MessageOut, MemberBrief
 from .converters import task_out, message_out, member_brief
@@ -59,12 +60,7 @@ class AssignRequest(BaseModel):
 
 # --- Helpers ---
 
-async def _get_project_chat_id(db: AsyncSession, project_id) -> uuid.UUID | None:
-    result = await db.execute(
-        select(Chat).where(Chat.project_id == project_id, Chat.kind == ChatKind.PROJECT)
-    )
-    chat = result.scalar_one_or_none()
-    return chat.id if chat else None
+# Removed _get_project_chat_id - no longer using Chat model
 
 
 async def _record_action(
@@ -76,15 +72,25 @@ async def _record_action(
     old_value: str | None = None,
     new_value: str | None = None,
 ):
-    """Record a task action in the audit log."""
-    db.add(TaskAction(
+    """Record a task action as Event (audit log)."""
+    payload = {
+        "action": action,
+    }
+    if field:
+        payload["field"] = field
+    if old_value:
+        payload["old_value"] = old_value
+    if new_value:
+        payload["new_value"] = new_value
+    
+    event = Event(
+        project_id=task.project_id,
         task_id=task.id,
+        type=f"task_{action.lower()}",  # task_created, task_assigned, etc.
         actor_id=actor.id,
-        action=action,
-        field=field,
-        old_value=old_value,
-        new_value=new_value,
-    ))
+        payload=payload,
+    )
+    db.add(event)
 
 
 async def _system_message(
@@ -96,93 +102,66 @@ async def _system_message(
     actor: Member | None = None,
     mentioned_members: list[Member] | None = None,
 ):
-    """Create system messages: one in project chat + one in task comments.
+    """Create system message as Event (replaces old dual Message approach).
     
     actor: who initiated the action (stored as actor_id)
     mentioned_members: members referenced in the message (stored in mentions array)
     """
     from ..ws.manager import manager
+    from ..models import Event
+    from .schemas import EventOut
+    from .converters import event_out, member_brief
 
     prefix = project_slug[:2].upper() if project_slug else "XX"
     key = f"{prefix}-{task.number}"
     task_text = task_text or chat_text
-    actor_slug = actor.slug if actor else "system"
-    actor_brief = MemberBrief(id=str(actor.id), slug=actor.slug, name=actor.name) if actor else None
+    actor_brief_obj = member_brief(actor) if actor else None
 
-    # Mentioned members as IDs (DB storage) and briefs (broadcast)
+    # Mentioned members as IDs and briefs
     mention_ids = [str(m.id) for m in (mentioned_members or [])]
-    mention_briefs = [MemberBrief(id=str(m.id), slug=m.slug, name=m.name) for m in (mentioned_members or [])]
+    mention_briefs = [member_brief(m) for m in (mentioned_members or [])]
 
-    chat_id = await _get_project_chat_id(db, task.project_id)
+    # Create single Event for task comment
+    event_payload = {
+        "content": task_text,
+        "mentions": mention_ids,
+    }
 
-    # 1. Task comment
-    task_msg = Message(
+    event = Event(
+        project_id=task.project_id,
         task_id=task.id,
-        author_type=AuthorType.SYSTEM,
-        author_id=None,
+        type="task_comment",
         actor_id=actor.id if actor else None,
-        content=task_text,
-        mentions=mention_ids,  # still stored as slugs in DB for compat
+        payload=event_payload,
     )
-    db.add(task_msg)
-
-    # 2. Chat message
-    chat_msg = None
-    if chat_id:
-        chat_msg = Message(
-            chat_id=chat_id,
-            author_type=AuthorType.SYSTEM,
-            author_id=None,
-            actor_id=actor.id if actor else None,
-            content=chat_text,
-            mentions=mention_ids,
-        )
-        db.add(chat_msg)
-
+    db.add(event)
     await db.flush()
 
-    now_iso = datetime.datetime.now(datetime.timezone.utc).isoformat()
+    # Build EventOut for broadcast (backward compatible with MessageOut format)
+    event_out_obj = event_out(event)
+    
+    # Build backward-compatible message format for WS broadcast
+    # Convert EventOut to MessageOut-like structure for existing clients
+    task_data = {
+        "id": event_out_obj.id,
+        "task_id": str(task.id),
+        "author_type": "system",
+        "author_id": None,
+        "author": None,
+        "actor": actor_brief_obj.model_dump() if actor_brief_obj else None,
+        "content": task_text,
+        "mentions": [mb.model_dump() for mb in mention_briefs],
+        "attachments": [],
+        "created_at": event_out_obj.created_at,
+        "project_id": str(task.project_id),
+    }
     
-    # Build MessageOut for task comment broadcast
-    task_msg_out = MessageOut(
-        id=str(task_msg.id),
-        task_id=str(task.id),
-        author_type=AuthorType.SYSTEM,
-        author_id=None,
-        author=None,
-        actor=actor_brief,
-        content=task_text,
-        mentions=mention_briefs,
-        attachments=[],
-        created_at=task_msg.created_at.isoformat() if task_msg.created_at else now_iso,
-    )
-    project_id = str(task.project_id)
-    task_data = task_msg_out.model_dump()
-    task_data["project_id"] = project_id
     await manager.broadcast_message(
-        project_id,
+        str(task.project_id),
         task_data,
         author_id=None,
     )
 
-    # Broadcast chat message
-    if chat_msg and chat_id:
-        chat_msg_out = MessageOut(
-            id=str(chat_msg.id),
-            chat_id=str(chat_id),
-            author_type=AuthorType.SYSTEM,
-            author_id=None,
-            author=None,
-            actor=actor_brief,
-            content=chat_text,
-            mentions=mention_briefs,
-            attachments=[],
-            created_at=chat_msg.created_at.isoformat() if chat_msg.created_at else now_iso,
-        )
-        chat_data = chat_msg_out.model_dump()
-        chat_data["project_id"] = project_id
-        await manager.broadcast_message(project_id, chat_data, author_id=None)
-
 
 async def _get_task(task_id: str, db: AsyncSession) -> Task:
     result = await db.execute(
@@ -314,7 +293,7 @@ async def create_task(
                 task.watcher_ids = [agent.id]
                 break
 
-    await _record_action(db, task, current_member, TaskActionType.CREATED)
+    await _record_action(db, task, current_member, "created")
 
     await db.commit()
     task_full = await _get_task(str(task.id), db)
@@ -356,12 +335,12 @@ async def update_task(
     now_str = datetime.datetime.now(datetime.timezone.utc).strftime("%H:%M UTC")
 
     if req.title is not None and req.title != task.title:
-        await _record_action(db, task, current_member, TaskActionType.TITLE_CHANGED,
+        await _record_action(db, task, current_member, "title_changed",
                              "title", task.title, req.title)
         task.title = req.title
 
     if req.description is not None and req.description != task.description:
-        await _record_action(db, task, current_member, TaskActionType.DESCRIPTION_CHANGED,
+        await _record_action(db, task, current_member, "description_changed",
                              "description", task.description or "", req.description)
         task.description = req.description
 
@@ -370,7 +349,7 @@ async def update_task(
 
     if req.status is not None and req.status != task.status:
         old_status = task.status
-        await _record_action(db, task, current_member, TaskActionType.STATUS_CHANGED,
+        await _record_action(db, task, current_member, "status_changed",
                              "status", old_status, req.status)
         task.status = req.status
         await _system_message(
@@ -382,7 +361,7 @@ async def update_task(
 
     if req.priority is not None and req.priority != task.priority:
         old_priority = task.priority
-        await _record_action(db, task, current_member, TaskActionType.PRIORITY_CHANGED,
+        await _record_action(db, task, current_member, "priority_changed",
                              "priority", old_priority, req.priority)
         task.priority = req.priority
 
@@ -396,7 +375,7 @@ async def update_task(
             task.assignee_id = new_assignee_id
             if new_assignee_id:
                 new_assignee = await _resolve_member(db, req.assignee_id)
-                await _record_action(db, task, current_member, TaskActionType.ASSIGNED,
+                await _record_action(db, task, current_member, "assigned",
                                      "assignee_id", str(old_assignee_id) if old_assignee_id else None,
                                      str(new_assignee_id))
                 await _system_message(
@@ -409,7 +388,7 @@ async def update_task(
                 if new_assignee_id not in (task.watcher_ids or []):
                     task.watcher_ids = (task.watcher_ids or []) + [new_assignee_id]
             else:
-                await _record_action(db, task, current_member, TaskActionType.UNASSIGNED,
+                await _record_action(db, task, current_member, "unassigned",
                                      "assignee_id", str(old_assignee_id), None)
                 await _system_message(
                     db, task,
@@ -423,7 +402,7 @@ async def update_task(
         new_reviewer_id = uuid.UUID(req.reviewer_id) if req.reviewer_id else None
         if new_reviewer_id != old_reviewer_id:
             task.reviewer_id = new_reviewer_id
-            await _record_action(db, task, current_member, TaskActionType.REVIEWER_CHANGED,
+            await _record_action(db, task, current_member, "reviewer_changed",
                                  "reviewer_id", str(old_reviewer_id) if old_reviewer_id else None,
                                  str(new_reviewer_id) if new_reviewer_id else None)
 
@@ -479,9 +458,9 @@ async def take_task(
     if current_member.id not in (task.watcher_ids or []):
         task.watcher_ids = (task.watcher_ids or []) + [current_member.id]
 
-    await _record_action(db, task, current_member, TaskActionType.ASSIGNED,
+    await _record_action(db, task, current_member, "assigned",
                          "assignee_id", None, str(current_member.id))
-    await _record_action(db, task, current_member, TaskActionType.STATUS_CHANGED,
+    await _record_action(db, task, current_member, "status_changed",
                          "status", TaskStatus.BACKLOG, TaskStatus.IN_PROGRESS)
 
     proj_slug = task.project.slug if task.project else ""
@@ -517,9 +496,9 @@ async def reject_task(
     task.status = TaskStatus.BACKLOG
 
     old_status = task.status
-    await _record_action(db, task, current_member, TaskActionType.UNASSIGNED,
+    await _record_action(db, task, current_member, "unassigned",
                          "assignee_id", str(old_assignee_id) if old_assignee_id else None, None)
-    await _record_action(db, task, current_member, TaskActionType.STATUS_CHANGED,
+    await _record_action(db, task, current_member, "status_changed",
                          "status", old_status, TaskStatus.BACKLOG)
 
     proj_slug = task.project.slug if task.project else ""
@@ -557,7 +536,7 @@ async def assign_task(
     if assignee.id not in (task.watcher_ids or []):
         task.watcher_ids = (task.watcher_ids or []) + [assignee.id]
 
-    await _record_action(db, task, current_member, TaskActionType.ASSIGNED,
+    await _record_action(db, task, current_member, "assigned",
                          "assignee_id", str(old_assignee_id) if old_assignee_id else None,
                          str(assignee.id))
 
@@ -589,7 +568,7 @@ async def watch_task(
     task = await _get_task(task_id, db)
     if current_member.id not in (task.watcher_ids or []):
         task.watcher_ids = (task.watcher_ids or []) + [current_member.id]
-        await _record_action(db, task, current_member, TaskActionType.WATCHER_ADDED,
+        await _record_action(db, task, current_member, "watcher_added",
                              "watcher_ids", None, str(current_member.id))
         await db.commit()
     return {"ok": True, "watcher_ids": [str(w) for w in (task.watcher_ids or [])]}
@@ -603,7 +582,7 @@ async def unwatch_task(
 ):
     task = await _get_task(task_id, db)
     task.watcher_ids = [w for w in (task.watcher_ids or []) if w != current_member.id]
-    await _record_action(db, task, current_member, TaskActionType.WATCHER_REMOVED,
+    await _record_action(db, task, current_member, "watcher_removed",
                          "watcher_ids", str(current_member.id), None)
     await db.commit()
     return {"ok": True, "watcher_ids": [str(w) for w in (task.watcher_ids or [])]}

src/tracker/app.py

@@ -169,14 +169,15 @@ app.add_middleware(
 )
 
 # Routers
-from .api import auth, members, projects, tasks, messages, steps, attachments, project_files, labels  # noqa: E402
+from .api import auth, members, projects, tasks, messages, events, steps, attachments, project_files, labels  # noqa: E402
 from .ws.handler import router as ws_router  # noqa: E402
 
 app.include_router(auth.router, prefix="/api/v1")
 app.include_router(members.router, prefix="/api/v1")
 app.include_router(projects.router, prefix="/api/v1")
 app.include_router(tasks.router, prefix="/api/v1")
-app.include_router(messages.router, prefix="/api/v1")
+app.include_router(messages.router, prefix="/api/v1")  # Backward compatibility
+app.include_router(events.router, prefix="/api/v1")    # New events API
 app.include_router(steps.router, prefix="/api/v1")
 app.include_router(attachments.router, prefix="/api/v1")
 app.include_router(project_files.router, prefix="/api/v1")

src/tracker/init_db.py

@@ -6,8 +6,8 @@ import logging
 
 from sqlalchemy.ext.asyncio import AsyncSession
 
-from .enums import AuthMethod, ChatKind, ListenMode, MemberRole, MemberStatus, MemberType, ProjectStatus
-from .models import Base, Member, Chat, Project, ProjectMember, AgentConfig
+from .enums import AuthMethod, ListenMode, MemberRole, MemberStatus, MemberType, ProjectStatus
+from .models import Base, Member, Project, ProjectMember, AgentConfig
 
 logger = logging.getLogger("tracker.init_db")
 
@@ -83,9 +83,7 @@ async def seed_dev_data(session: AsyncSession):
     session.add(project)
     await session.flush()
 
-    # Project chat
-    project_chat = Chat(kind=ChatKind.PROJECT, project_id=project.id)
-    session.add(project_chat)
+    # Project chat - REMOVED: using Events instead of Chat+Message
 
     # Project members
     session.add(ProjectMember(project_id=project.id, member_id=admin.id, role=MemberRole.OWNER))
@@ -107,12 +105,10 @@ async def seed_dev_data(session: AsyncSession):
 
     session.add(ProjectMember(project_id=project.id, member_id=bridge.id, role=MemberRole.MEMBER))
 
-    # Lobby chat
-    lobby = Chat(kind=ChatKind.LOBBY, project_id=None)
-    session.add(lobby)
+    # Lobby chat - REMOVED: using Events instead
 
     await session.commit()
-    logger.info("Dev seed: admin, coder, project team-board (id=%s), lobby", project.id)
+    logger.info("Dev seed: admin, coder, project team-board (id=%s)", project.id)
 
 
 async def reset_db():

src/tracker/models/__init__.py

@@ -3,8 +3,8 @@
 from .base import Base
 from .member import AgentConfig, Member
 from .project import Project, ProjectMember
-from .task import Label, Step, Task, TaskAction, TaskLabel, TaskLink
-from .chat import Attachment, Chat, Message
+from .task import Label, Step, Task, TaskLabel, TaskLink
+from .event import Event, EventAttachment
 from .project_file import ProjectFile
 
 __all__ = [
@@ -14,11 +14,10 @@ __all__ = [
     "Project",
     "ProjectMember",
     "Task",
-    "TaskAction",
-    "TaskLink",
+    "Label",
+    "TaskLabel",
     "Step",
-    "Chat",
-    "Message",
-    "Attachment",
+    "Event",
+    "EventAttachment",
     "ProjectFile",
 ]

src/tracker/models/event.py

@@ -0,0 +1,72 @@
+"""Event model — unified event store replacing messages + task_actions."""
+
+import uuid
+from typing import TYPE_CHECKING
+
+from sqlalchemy import ForeignKey, Integer, String, Text
+from sqlalchemy.dialects.postgresql import ARRAY, JSONB, UUID
+from sqlalchemy.orm import Mapped, mapped_column, relationship
+
+from .base import Base
+
+if TYPE_CHECKING:
+    from .member import Member
+    from .project import Project
+    from .task import Task
+
+
+class Event(Base):
+    """Unified event — chat messages, task comments, status changes, etc."""
+    __tablename__ = "events"
+
+    project_id: Mapped[uuid.UUID] = mapped_column(
+        UUID(as_uuid=True), ForeignKey("projects.id"), nullable=False, index=True
+    )
+    type: Mapped[str] = mapped_column(String(50), nullable=False, index=True)
+    # Types: chat_message, task_comment, task_created, task_status,
+    #        task_assigned, task_unassigned, task_updated, task_label_add, task_label_remove
+
+    actor_id: Mapped[uuid.UUID | None] = mapped_column(ForeignKey("members.id"), nullable=True)
+    task_id: Mapped[uuid.UUID | None] = mapped_column(
+        UUID(as_uuid=True), ForeignKey("tasks.id", ondelete="CASCADE"), nullable=True, index=True
+    )
+    parent_id: Mapped[uuid.UUID | None] = mapped_column(
+        UUID(as_uuid=True), ForeignKey("events.id"), nullable=True
+    )
+
+    # Payload — all event-specific data
+    payload: Mapped[dict] = mapped_column(JSONB, nullable=False, default=dict)
+    # chat_message:  {content, mentions?, thinking?, voice_url?, tool_log?}
+    # task_comment:  {content, mentions?, thinking?, tool_log?}
+    # task_created:  {title, status, priority, assignee?}
+    # task_status:   {from, to}
+    # task_assigned: {assignee, previous?}
+    # task_unassigned: {previous}
+    # task_updated:  {field, from, to}
+
+    # Relationships
+    project: Mapped["Project"] = relationship()
+    actor: Mapped["Member | None"] = relationship(foreign_keys=[actor_id])
+    task: Mapped["Task | None"] = relationship()
+    attachments: Mapped[list["EventAttachment"]] = relationship(
+        back_populates="event", cascade="all, delete-orphan"
+    )
+    replies: Mapped[list["Event"]] = relationship(back_populates="parent")
+    parent: Mapped["Event | None"] = relationship(
+        back_populates="replies", remote_side="Event.id"
+    )
+
+
+class EventAttachment(Base):
+    """File attachment on an event."""
+    __tablename__ = "event_attachments"
+
+    event_id: Mapped[uuid.UUID] = mapped_column(
+        UUID(as_uuid=True), ForeignKey("events.id"), nullable=False
+    )
+    filename: Mapped[str] = mapped_column(String(500), nullable=False)
+    mime_type: Mapped[str | None] = mapped_column(String(100))
+    size: Mapped[int] = mapped_column(Integer, default=0)
+    storage_path: Mapped[str] = mapped_column(String(1000), nullable=False)
+
+    event: Mapped["Event"] = relationship(back_populates="attachments")

src/tracker/models/task.py

@@ -81,15 +81,4 @@ class TaskLink(Base):
     target: Mapped["Task"] = relationship(foreign_keys=[target_id])
 
 
-class TaskAction(Base):
-    __tablename__ = "task_actions"
-
-    task_id: Mapped[uuid.UUID] = mapped_column(ForeignKey("tasks.id", ondelete="CASCADE"))
-    actor_id: Mapped[uuid.UUID] = mapped_column(ForeignKey("members.id"))
-    action: Mapped[str] = mapped_column(String(50), nullable=False)  # created, status_changed, assigned, etc.
-    field: Mapped[str | None] = mapped_column(String(100))  # какое поле изменилось
-    old_value: Mapped[str | None] = mapped_column(Text)
-    new_value: Mapped[str | None] = mapped_column(Text)
-
-    task: Mapped["Task"] = relationship()
-    actor: Mapped["Member"] = relationship()
+    # TaskAction removed — replaced by Event model

src/tracker/ws/handler.py

@@ -12,7 +12,8 @@ from ..enums import (
     AuthMethod, ChatKind, ListenMode, MemberRole, MemberStatus, MemberType,
     ProjectStatus, WSEventType,
 )
-from ..models import Member, AgentConfig, Chat, Message, Project, ProjectMember
+from ..models import Member, AgentConfig, Project, ProjectMember, Task, Event
+from ..models.chat import Chat, Message  # Legacy imports
 from ..api.schemas import MessageOut, MemberBrief
 from .manager import ConnectedClient, manager
 
@@ -195,10 +196,7 @@ async def _authenticate(ws: WebSocket, token: str, on_behalf_of: str | None = No
         effective_member.status = MemberStatus.ONLINE
         await db.commit()
 
-        # Get lobby chat + projects
-        lobby = await db.execute(select(Chat).where(Chat.kind == ChatKind.LOBBY))
-        lobby_chat = lobby.scalar_one_or_none()
-
+        # Get projects (no more lobby/chat dependency)
         if effective_member.role == MemberRole.OWNER:
             projects = await db.execute(select(Project).where(Project.status == ProjectStatus.ACTIVE))
         else:
@@ -210,15 +208,11 @@ async def _authenticate(ws: WebSocket, token: str, on_behalf_of: str | None = No
 
         project_list = []
         for p in projects.scalars():
-            chat_result = await db.execute(
-                select(Chat).where(Chat.project_id == p.id, Chat.kind == "project")
-            )
-            chat = chat_result.scalar_one_or_none()
             project_list.append({
                 "id": str(p.id),
                 "slug": p.slug,
                 "name": p.name,
-                "chat_id": str(chat.id) if chat else None,
+                "chat_id": None,  # Legacy field - no longer used
             })
 
         # Auto-subscribe
@@ -237,7 +231,7 @@ async def _authenticate(ws: WebSocket, token: str, on_behalf_of: str | None = No
             "member_id": str(effective_member.id),
             "slug": effective_member.slug,
             "name": effective_member.name,
-            "lobby_chat_id": str(lobby_chat.id) if lobby_chat else None,
+            "lobby_chat_id": None,  # Legacy field - no longer used
             "projects": project_list,
             "online": online_list,
         }
@@ -315,7 +309,8 @@ async def _handle_chat_send(session_id: str, data: dict):
     if not client:
         return
 
-    chat_id = data.get("chat_id")
+    chat_id = data.get("chat_id")  # legacy - will map to project_id
+    project_id = data.get("project_id")  # preferred
     task_id = data.get("task_id")
     content = data.get("content", "")
     thinking = data.get("thinking")
@@ -332,56 +327,83 @@ async def _handle_chat_send(session_id: str, data: dict):
             await client.ws.send_json({"type": WSEventType.ERROR, "message": "Member not found or inactive"})
             return
 
-        msg = Message(
-            chat_id=uuid.UUID(chat_id) if chat_id else None,
-            task_id=uuid.UUID(task_id) if task_id else None,
-            author_type=member.type,
-            author_id=member.id,
-            content=content,
-            thinking=thinking,
-            tool_log=tool_log,
-            mentions=mentions,
-        )
-        db.add(msg)
-        await db.commit()
-        await db.refresh(msg)
+        # Resolve project_id
+        resolved_project_id = None
+        event_type = "chat_message"
         
-        msg_data = _to_message_out(msg, member).model_dump()
-
-        # Resolve project_id and inject into message data
-        project_id = None
-        if chat_id:
+        if project_id:
+            resolved_project_id = uuid.UUID(project_id)
+        elif chat_id:
+            # Legacy: resolve project_id from chat_id
             chat_result = await db.execute(select(Chat).where(Chat.id == uuid.UUID(chat_id)))
             chat = chat_result.scalar_one_or_none()
             if chat and chat.project_id:
-                project_id = str(chat.project_id)
+                resolved_project_id = chat.project_id
             elif chat and chat.kind == ChatKind.LOBBY:
-                await manager.broadcast_all(
-                    {"type": WSEventType.MESSAGE_NEW, "data": msg_data},
-                    exclude_member_id=client.member_id,
-                )
+                # Skip lobby for now - Events need project_id
+                await client.ws.send_json({"type": WSEventType.ERROR, "message": "Lobby chat not supported yet"})
                 return
         elif task_id:
-            from ..models import Task as TaskModel
-            task_result = await db.execute(select(TaskModel).where(TaskModel.id == uuid.UUID(task_id)))
+            # Task comment
+            event_type = "task_comment"
+            task_result = await db.execute(select(Task).where(Task.id == uuid.UUID(task_id)))
             task_obj = task_result.scalar_one_or_none()
             if task_obj:
-                project_id = str(task_obj.project_id)
+                resolved_project_id = task_obj.project_id
 
-        if project_id:
-            msg_data["project_id"] = project_id
+        if not resolved_project_id:
+            await client.ws.send_json({"type": WSEventType.ERROR, "message": "project_id required"})
+            return
 
-        if project_id:
-            await manager.broadcast_message(
-                project_id, msg_data,
-                author_id=client.member_id,
-                author_session_id=session_id,
-            )
-        else:
-            await manager.broadcast_all(
-                {"type": WSEventType.MESSAGE_NEW, "data": msg_data},
-                exclude_member_id=client.member_id,
-            )
+        # Create Event
+        from ..models import Event
+        
+        event_payload = {
+            "content": content,
+            "mentions": mentions,
+        }
+        if thinking:
+            event_payload["thinking"] = thinking
+        if tool_log:
+            event_payload["tool_log"] = tool_log
+
+        event = Event(
+            project_id=resolved_project_id,
+            task_id=uuid.UUID(task_id) if task_id else None,
+            type=event_type,
+            actor_id=member.id,
+            payload=event_payload,
+        )
+        db.add(event)
+        await db.commit()
+        await db.refresh(event)
+
+        # Build backward-compatible message format for WS broadcast
+        from ..api.converters import member_brief
+        actor_brief_obj = member_brief(member)
+        
+        event_data = {
+            "id": str(event.id),
+            "task_id": str(event.task_id) if event.task_id else None,
+            "chat_id": chat_id,  # Keep for backward compatibility
+            "author_type": member.type,
+            "author_id": str(member.id),
+            "author": actor_brief_obj.model_dump() if actor_brief_obj else None,
+            "actor": actor_brief_obj.model_dump() if actor_brief_obj else None,
+            "content": content,
+            "thinking": thinking,
+            "tool_log": tool_log,
+            "mentions": [{"id": mid, "slug": "", "name": ""} for mid in mentions],  # simplified mentions
+            "attachments": [],
+            "created_at": event.created_at.isoformat() if event.created_at else "",
+            "project_id": str(resolved_project_id),
+        }
+
+        await manager.broadcast_message(
+            str(resolved_project_id), event_data,
+            author_id=client.member_id,
+            author_session_id=session_id,
+        )
 
 
 async def _handle_agent_stream(session_id: str, event_type: str, data: dict):