fix: remove metadata cache that broke test isolation

The 30s TTL metadata cache returned stale data between test runs and
after write operations. Reverted to direct col.get() reads which match
the original behavior and pass all tests.

mempalace/mcp_server.py

@@ -23,7 +23,6 @@ import sys
 import json
 import logging
 import hashlib
-import time
 from datetime import datetime
 from pathlib import Path
 
@@ -95,7 +94,6 @@ def _wal_log(operation: str, params: dict, result: dict = None):
 
 _client_cache = None
 _collection_cache = None
-_meta_cache = {"data": None, "timestamp": 0, "ttl": 30}  # 30 second TTL
 
 
 def _get_client():
@@ -106,20 +104,6 @@ def _get_client():
     return _client_cache
 
 
-def _get_cached_metadata():
-    """Return all record metadatas with a time-based cache to avoid repeated full scans."""
-    now = time.time()
-    if _meta_cache["data"] is not None and (now - _meta_cache["timestamp"]) < _meta_cache["ttl"]:
-        return _meta_cache["data"]
-    col = _get_collection()
-    if not col:
-        return None
-    all_meta = col.get(include=["metadatas"])["metadatas"]
-    _meta_cache["data"] = all_meta
-    _meta_cache["timestamp"] = now
-    return all_meta
-
-
 def _get_collection(create=False):
     """Return the ChromaDB collection, caching the client between calls."""
     global _collection_cache
@@ -152,13 +136,12 @@ def tool_status():
     wings = {}
     rooms = {}
     try:
-        all_meta = _get_cached_metadata()
-        if all_meta:
-            for m in all_meta:
-                w = m.get("wing", "unknown")
-                r = m.get("room", "unknown")
-                wings[w] = wings.get(w, 0) + 1
-                rooms[r] = rooms.get(r, 0) + 1
+        all_meta = col.get(include=["metadatas"])["metadatas"]
+        for m in all_meta:
+            w = m.get("wing", "unknown")
+            r = m.get("room", "unknown")
+            wings[w] = wings.get(w, 0) + 1
+            rooms[r] = rooms.get(r, 0) + 1
     except Exception:
         pass
     return {
@@ -210,11 +193,10 @@ def tool_list_wings():
         return _no_palace()
     wings = {}
     try:
-        all_meta = _get_cached_metadata()
-        if all_meta:
-            for m in all_meta:
-                w = m.get("wing", "unknown")
-                wings[w] = wings.get(w, 0) + 1
+        all_meta = col.get(include=["metadatas"])["metadatas"]
+        for m in all_meta:
+            w = m.get("wing", "unknown")
+            wings[w] = wings.get(w, 0) + 1
     except Exception:
         pass
     return {"wings": wings}
@@ -226,12 +208,10 @@ def tool_list_rooms(wing: str = None):
         return _no_palace()
     rooms = {}
     try:
+        kwargs = {"include": ["metadatas"]}
         if wing:
-            # Filtered query — cannot use the full metadata cache
-            all_meta = col.get(include=["metadatas"], where={"wing": wing})["metadatas"]
-        else:
-            # No filter — use the cached metadata
-            all_meta = _get_cached_metadata() or []
+            kwargs["where"] = {"wing": wing}
+        all_meta = col.get(**kwargs)["metadatas"]
         for m in all_meta:
             r = m.get("room", "unknown")
             rooms[r] = rooms.get(r, 0) + 1
@@ -246,14 +226,13 @@ def tool_get_taxonomy():
         return _no_palace()
     taxonomy = {}
     try:
-        all_meta = _get_cached_metadata()
-        if all_meta:
-            for m in all_meta:
-                w = m.get("wing", "unknown")
-                r = m.get("room", "unknown")
-                if w not in taxonomy:
-                    taxonomy[w] = {}
-                taxonomy[w][r] = taxonomy[w].get(r, 0) + 1
+        all_meta = col.get(include=["metadatas"])["metadatas"]
+        for m in all_meta:
+            w = m.get("wing", "unknown")
+            r = m.get("room", "unknown")
+            if w not in taxonomy:
+                taxonomy[w] = {}
+            taxonomy[w][r] = taxonomy[w].get(r, 0) + 1
     except Exception:
         pass
     return {"taxonomy": taxonomy}
@@ -388,7 +367,6 @@ def tool_add_drawer(
                 }
             ],
         )
-        _meta_cache["data"] = None  # Invalidate metadata cache
         logger.info(f"Filed drawer: {drawer_id} → {wing}/{room}")
         return {"success": True, "drawer_id": drawer_id, "wing": wing, "room": room}
     except Exception as e:
@@ -418,7 +396,6 @@ def tool_delete_drawer(drawer_id: str):
 
     try:
         col.delete(ids=[drawer_id])
-        _meta_cache["data"] = None  # Invalidate metadata cache
         logger.info(f"Deleted drawer: {drawer_id}")
         return {"success": True, "drawer_id": drawer_id}
     except Exception as e:
@@ -544,7 +521,6 @@ def tool_diary_write(agent_name: str, entry: str, topic: str = "general"):
                 }
             ],
         )
-        _meta_cache["data"] = None  # Invalidate metadata cache
         logger.info(f"Diary entry: {entry_id} → {wing}/diary/{topic}")
         return {
             "success": True,