fix: RAG keyword fallback leaked owner-less documents across users (#1722)

VectorRAG.search() filters with ChromaDB where={"owner": owner}, returning only
documents whose owner equals the requesting user. The keyword fallback
(_keyword_search_fallback, used when the primary query raises) guarded with
`if doc_owner and doc_owner != owner: continue`, so a document with a
missing/empty owner fell through and was returned to whichever user issued the
query — a cross-user information leak on the fallback path.

Match the primary path's strict filter: skip any doc whose owner != the
requested owner, including owner-less docs.

Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>

src/rag_vector.py

@@ -260,8 +260,11 @@ class VectorRAG:
             for i, doc in enumerate(all_docs["documents"]):
                 meta = all_docs["metadatas"][i]
                 if owner:
-                    doc_owner = meta.get("owner")
-                    if doc_owner and doc_owner != owner:
+                    # Match the primary path's strict where={"owner": owner}
+                    # filter. The old `if doc_owner and doc_owner != owner`
+                    # let docs with a missing/empty owner fall through, leaking
+                    # owner-less documents into another user's results.
+                    if meta.get("owner") != owner:
                         continue
                 doc_lower = doc.lower()
                 score = sum(1 for w in query_words if w in doc_lower)

tests/test_rag_keyword_fallback_owner.py

@@ -0,0 +1,57 @@
+"""Regression: VectorRAG._keyword_search_fallback must not leak owner-less docs
+across users.
+
+The primary hybrid search filters with ChromaDB ``where={"owner": owner}``,
+which returns only documents whose ``owner == owner`` (documents with no owner
+are excluded). The keyword fallback used
+``if doc_owner and doc_owner != owner: continue``, so a document with a
+missing/empty owner fell through the guard and was returned to whichever user
+issued the query — a cross-user leak whenever the primary path errored and fell
+back to keyword search.
+"""
+from src.rag_vector import VectorRAG
+
+
+class _FakeCollection:
+    def __init__(self, docs):
+        # docs: list of (id, text, metadata)
+        self._docs = docs
+
+    def count(self):
+        return len(self._docs)
+
+    def get(self, include=None):
+        return {
+            "ids": [d[0] for d in self._docs],
+            "documents": [d[1] for d in self._docs],
+            "metadatas": [d[2] for d in self._docs],
+        }
+
+
+def _store(docs):
+    store = VectorRAG.__new__(VectorRAG)
+    store._collection = _FakeCollection(docs)
+    return store
+
+
+def test_ownerless_doc_not_leaked_to_user():
+    store = _store([
+        ("a", "alice secret project", {"owner": "alice"}),
+        ("b", "bob secret project", {"owner": "bob"}),
+        ("c", "ownerless secret project", {}),          # no owner key
+    ])
+    results = store._keyword_search_fallback("secret project", k=10, owner="alice")
+    ids = {r["id"] for r in results}
+    assert ids == {"a"}          # only alice's doc
+    assert "b" not in ids        # another user's doc excluded (already was)
+    assert "c" not in ids        # owner-less doc must NOT leak (the fix)
+
+
+def test_no_owner_filter_returns_all():
+    store = _store([
+        ("a", "shared note", {"owner": "alice"}),
+        ("c", "shared note", {}),
+    ])
+    results = store._keyword_search_fallback("shared note", k=10, owner=None)
+    ids = {r["id"] for r in results}
+    assert ids == {"a", "c"}     # no owner requested → no filtering