feat: add matrix staged attachment state

adapter/matrix/store.py

@@ -1,5 +1,8 @@
 from __future__ import annotations
 
+import asyncio
+from weakref import WeakValueDictionary
+
 from core.store import StateStore
 
 ROOM_META_PREFIX = "matrix_room:"
@@ -9,6 +12,8 @@ SKILLS_MSG_PREFIX = "matrix_skills_msg:"
 PENDING_CONFIRM_PREFIX = "matrix_pending_confirm:"
 LOAD_PENDING_PREFIX = "matrix_load_pending:"
 RESET_PENDING_PREFIX = "matrix_reset_pending:"
+STAGED_ATTACHMENTS_PREFIX = "matrix_staged_attachments:"
+_STAGED_ATTACHMENTS_LOCKS: WeakValueDictionary[str, asyncio.Lock] = WeakValueDictionary()
 
 
 async def get_room_meta(store: StateStore, room_id: str) -> dict | None:
@@ -126,3 +131,66 @@ async def set_reset_pending(
 
 async def clear_reset_pending(store: StateStore, user_id: str, room_id: str) -> None:
     await store.delete(_reset_pending_key(user_id, room_id))
+
+
+def _staged_attachments_key(room_id: str, user_id: str) -> str:
+    return f"{STAGED_ATTACHMENTS_PREFIX}{room_id}:{user_id}"
+
+
+def _staged_attachments_lock(room_id: str, user_id: str) -> asyncio.Lock:
+    key = _staged_attachments_key(room_id, user_id)
+    lock = _STAGED_ATTACHMENTS_LOCKS.get(key)
+    if lock is None:
+        lock = asyncio.Lock()
+        _STAGED_ATTACHMENTS_LOCKS[key] = lock
+    return lock
+
+
+async def get_staged_attachments(
+    store: StateStore, room_id: str, user_id: str
+) -> list[dict]:
+    data = await store.get(_staged_attachments_key(room_id, user_id))
+    if not isinstance(data, dict):
+        return []
+
+    attachments = data.get("attachments")
+    if not isinstance(attachments, list):
+        return []
+
+    return [attachment for attachment in attachments if isinstance(attachment, dict)]
+
+
+async def add_staged_attachment(
+    store: StateStore, room_id: str, user_id: str, attachment: dict
+) -> None:
+    async with _staged_attachments_lock(room_id, user_id):
+        attachments = await get_staged_attachments(store, room_id, user_id)
+        attachments.append(attachment)
+        await store.set(
+            _staged_attachments_key(room_id, user_id), {"attachments": attachments}
+        )
+
+
+async def remove_staged_attachment_at(
+    store: StateStore, room_id: str, user_id: str, index: int
+) -> dict | None:
+    async with _staged_attachments_lock(room_id, user_id):
+        attachments = await get_staged_attachments(store, room_id, user_id)
+        if index < 0 or index >= len(attachments):
+            return None
+
+        removed = attachments.pop(index)
+        if attachments:
+            await store.set(
+                _staged_attachments_key(room_id, user_id), {"attachments": attachments}
+            )
+        else:
+            await store.delete(_staged_attachments_key(room_id, user_id))
+        return removed
+
+
+async def clear_staged_attachments(
+    store: StateStore, room_id: str, user_id: str
+) -> None:
+    async with _staged_attachments_lock(room_id, user_id):
+        await store.delete(_staged_attachments_key(room_id, user_id))