feat(chats): add role-based member management APIs

- add owner/admin/member permission checks

- implement member add/remove, role updates, and leave flow

- add chat title update endpoint for manageable chat types

app/chats/router.py

@@ -1,9 +1,26 @@
-from fastapi import APIRouter, Depends
+from fastapi import APIRouter, Depends, status
 from sqlalchemy.ext.asyncio import AsyncSession
 
 from app.auth.service import get_current_user
-from app.chats.schemas import ChatCreateRequest, ChatDetailRead, ChatRead
-from app.chats.service import create_chat_for_user, get_chat_for_user, get_chats_for_user
+from app.chats.schemas import (
+    ChatCreateRequest,
+    ChatDetailRead,
+    ChatMemberAddRequest,
+    ChatMemberRead,
+    ChatMemberRoleUpdateRequest,
+    ChatRead,
+    ChatTitleUpdateRequest,
+)
+from app.chats.service import (
+    add_chat_member_for_user,
+    create_chat_for_user,
+    get_chat_for_user,
+    get_chats_for_user,
+    leave_chat_for_user,
+    remove_chat_member_for_user,
+    update_chat_member_role_for_user,
+    update_chat_title_for_user,
+)
 from app.database.session import get_db
 from app.users.models import User
 
@@ -43,3 +60,69 @@ async def get_chat(
         created_at=chat.created_at,
         members=members,
     )
+
+
+@router.patch("/{chat_id}/title", response_model=ChatRead)
+async def update_chat_title(
+    chat_id: int,
+    payload: ChatTitleUpdateRequest,
+    db: AsyncSession = Depends(get_db),
+    current_user: User = Depends(get_current_user),
+) -> ChatRead:
+    return await update_chat_title_for_user(db, chat_id=chat_id, user_id=current_user.id, payload=payload)
+
+
+@router.get("/{chat_id}/members", response_model=list[ChatMemberRead])
+async def list_chat_members(
+    chat_id: int,
+    db: AsyncSession = Depends(get_db),
+    current_user: User = Depends(get_current_user),
+) -> list[ChatMemberRead]:
+    _chat, members = await get_chat_for_user(db, chat_id=chat_id, user_id=current_user.id)
+    return members
+
+
+@router.post("/{chat_id}/members", response_model=ChatMemberRead, status_code=status.HTTP_201_CREATED)
+async def add_chat_member(
+    chat_id: int,
+    payload: ChatMemberAddRequest,
+    db: AsyncSession = Depends(get_db),
+    current_user: User = Depends(get_current_user),
+) -> ChatMemberRead:
+    return await add_chat_member_for_user(db, chat_id=chat_id, actor_user_id=current_user.id, target_user_id=payload.user_id)
+
+
+@router.patch("/{chat_id}/members/{user_id}/role", response_model=ChatMemberRead)
+async def update_chat_member_role(
+    chat_id: int,
+    user_id: int,
+    payload: ChatMemberRoleUpdateRequest,
+    db: AsyncSession = Depends(get_db),
+    current_user: User = Depends(get_current_user),
+) -> ChatMemberRead:
+    return await update_chat_member_role_for_user(
+        db,
+        chat_id=chat_id,
+        actor_user_id=current_user.id,
+        target_user_id=user_id,
+        role=payload.role,
+    )
+
+
+@router.delete("/{chat_id}/members/{user_id}", status_code=status.HTTP_204_NO_CONTENT)
+async def remove_chat_member(
+    chat_id: int,
+    user_id: int,
+    db: AsyncSession = Depends(get_db),
+    current_user: User = Depends(get_current_user),
+) -> None:
+    await remove_chat_member_for_user(db, chat_id=chat_id, actor_user_id=current_user.id, target_user_id=user_id)
+
+
+@router.post("/{chat_id}/leave", status_code=status.HTTP_204_NO_CONTENT)
+async def leave_chat(
+    chat_id: int,
+    db: AsyncSession = Depends(get_db),
+    current_user: User = Depends(get_current_user),
+) -> None:
+    await leave_chat_for_user(db, chat_id=chat_id, user_id=current_user.id)