diff --git a/pyproject.toml b/pyproject.toml
index b8aa9d4..8fbe0b1 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -4,7 +4,7 @@ build-backend = "hatchling.build"
 
 [project]
 name = "ratatoskr"
-version = "0.20.12"
+version = "0.20.13"
 description = "Worldtree Conversation API debug TUI — multi-pane observability dashboard"
 readme = "README.md"
 requires-python = ">=3.12"
diff --git a/src/ratatoskr/provider/memory_store.py b/src/ratatoskr/provider/memory_store.py
index 937f91e..87bc495 100644
--- a/src/ratatoskr/provider/memory_store.py
+++ b/src/ratatoskr/provider/memory_store.py
@@ -383,6 +383,8 @@ class RatatoskrMemoryStore:
         scope_all = scope_all or {}
         scope_any = scope_any or []
         _validate_scope(scope_all, scope_any)  # PRE-002 (same lattice as search)
+        if sort is not None and not isinstance(sort, dict):  # PRE-003: malformed sort => reject, never crash
+            raise InvalidArguments("sort must be an object with field and direction")
         field = (sort or {}).get("field", "updated_at")
         direction = (sort or {}).get("direction", "desc")
         if field not in _SORTABLE_FIELD_NAMES or direction not in ("asc", "desc"):  # PRE-003
diff --git a/tests/test_provider_memory.py b/tests/test_provider_memory.py
index ed42955..bf10c12 100644
--- a/tests/test_provider_memory.py
+++ b/tests/test_provider_memory.py
@@ -427,6 +427,14 @@ async def test_scan_unadvertised_sort_field_rejected():
         await store.scan(scope_all={"end_user": "u1"}, limit=3, sort={"field": "salience", "direction": "desc"})
 
 
+async def test_scan_non_dict_sort_rejected():
+    # PRE-003: a truthy non-dict sort (caller-controlled) -> InvalidArguments, never AttributeError.
+    store = open_memory_store(":memory:", embedding_dim=EMBEDDING_DIM)
+    for bad in ("updated_at", ["updated_at"], 5):
+        with pytest.raises(InvalidArguments):
+            await store.scan(scope_all={"end_user": "u1"}, limit=3, sort=bad)
+
+
 async def test_scan_records_carry_person_prime_filter_fields():
     # The client _scan_filter_matches keys on agent_id + subject + worldtree_scope; a record
     # missing any is silently dropped -> the scan record must carry them verbatim.
diff --git a/uv.lock b/uv.lock
index b1553fc..bdfd356 100644
--- a/uv.lock
+++ b/uv.lock
@@ -1052,7 +1052,7 @@ wheels = [
 
 [[package]]
 name = "ratatoskr"
-version = "0.20.12"
+version = "0.20.13"
 source = { editable = "." }
 dependencies = [
     { name = "httpx" },