feat(threads): add basic message thread API and web thread panel

app/messages/repository.py

@@ -124,6 +124,34 @@ async def search_messages(
     return list(result.scalars().all())
 
 
+async def list_message_thread(
+    db: AsyncSession,
+    *,
+    root_message_id: int,
+    user_id: int,
+    limit: int = 100,
+) -> list[Message]:
+    root = await get_message_by_id(db, root_message_id)
+    if not root:
+        return []
+    stmt = (
+        select(Message)
+        .outerjoin(
+            MessageHidden,
+            (MessageHidden.message_id == Message.id) & (MessageHidden.user_id == user_id),
+        )
+        .where(
+            Message.chat_id == root.chat_id,
+            MessageHidden.id.is_(None),
+            (Message.id == root_message_id) | (Message.reply_to_message_id == root_message_id),
+        )
+        .order_by(Message.id.asc())
+        .limit(max(1, min(limit, 200)))
+    )
+    result = await db.execute(stmt)
+    return list(result.scalars().all())
+
+
 async def delete_message(db: AsyncSession, message: Message) -> None:
     await db.delete(message)
 

app/messages/router.py

@@ -20,6 +20,7 @@ from app.messages.service import (
     delete_message_for_all,
     forward_message,
     forward_message_bulk,
+    get_message_thread,
     get_messages,
     list_message_reactions,
     search_messages,
@@ -59,6 +60,16 @@ async def search_messages_endpoint(
     return await search_messages(db, user_id=current_user.id, query=query, chat_id=chat_id, limit=limit)
 
 
+@router.get("/{message_id}/thread", response_model=list[MessageRead])
+async def message_thread(
+    message_id: int,
+    limit: int = 100,
+    db: AsyncSession = Depends(get_db),
+    current_user: User = Depends(get_current_user),
+) -> list[MessageRead]:
+    return await get_message_thread(db, message_id=message_id, user_id=current_user.id, limit=limit)
+
+
 @router.get("/{chat_id}", response_model=list[MessageRead])
 async def list_messages(
     chat_id: int,

app/messages/service.py

@@ -177,6 +177,20 @@ async def search_messages(
     )
 
 
+async def get_message_thread(
+    db: AsyncSession,
+    *,
+    message_id: int,
+    user_id: int,
+    limit: int = 100,
+) -> list[Message]:
+    root = await repository.get_message_by_id(db, message_id)
+    if not root:
+        raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="Message not found")
+    await ensure_chat_membership(db, chat_id=root.chat_id, user_id=user_id)
+    return await repository.list_message_thread(db, root_message_id=message_id, user_id=user_id, limit=limit)
+
+
 async def update_message(
     db: AsyncSession,
     *,