diff --git a/mempalace/hallways.py b/mempalace/hallways.py
index be3fe85..9bee6c6 100644
--- a/mempalace/hallways.py
+++ b/mempalace/hallways.py
@@ -179,7 +179,12 @@ def compute_hallways_for_wing(
 
     Args:
         wing: wing name to scan.
-        col: ChromaDB collection — must support ``.get(where=..., include=...)``.
+        col: ChromaDB collection — must support ``.count()`` and paginated
+            ``.get(limit=..., offset=..., include=...)``. The fetch is filtered
+            to ``wing`` client-side rather than via ``.get(where={"wing": ...})``,
+            which binds one SQL variable per matched id and overflows SQLite's
+            ``SQLITE_MAX_VARIABLE_NUMBER`` on large wings (#1619). Fake
+            collections and alternate backends must implement this shape.
             If ``None``, returns ``[]`` (caller didn't supply a backing
             store, so nothing to compute against). Tests pass a controlled
             MagicMock.