chore(cancel): address Copilot review nits

- console/server.py: replace a stale hard-coded `session_routes.py:852-854`
  comment reference (already drifted to make_close_handler's signature) with
  a by-name reference to make_close_handler's not-found path.
- test_cancel.py: rename test_marks_most_recent_action_unknown ->
  test_marks_in_flight_action_unknown; the disposition marks the first
  unanswered (in-flight) call, not the most recent — they merely coincide in
  this two-call case.

tests/test_cancel.py

@@ -984,9 +984,10 @@ class TestCancelledAgentDisposition:
         assert "no side effects" in out
         assert "UNKNOWN" not in out
 
-    def test_marks_most_recent_action_unknown(self, tmp_db):
+    def test_marks_in_flight_action_unknown(self, tmp_db):
         session = _make_session()
-        # bash completed; web_fetch was in flight (issued, no result yet).
+        # bash completed; web_fetch was in flight (issued, no result yet) —
+        # the first unanswered call is the in-flight boundary.
         msgs = [
             self._assistant("t1", "bash"),
             self._result("t1"),

turnstone/console/server.py

@@ -3928,12 +3928,12 @@ async def _fanout_on_children(
                 # behaviour parity with the pre-lift outcome.
                 # NOTE: this branch is reachable from the cancel-cascade
                 # caller (``_cascade_cancel_to_children``) but unreachable
-                # from the close-cascade caller (``close_all_children``); the
-                # close handler at ``session_routes.py:852-854`` 404s
-                # for both missing and already-closed-evicted rows and
-                # never emits a 400 "No session". Kept as shared code
-                # rather than gated by caller — the branch is cheap and
-                # the symmetry makes future cascade verbs easier to add.
+                # from the close-cascade caller (``close_all_children``):
+                # ``make_close_handler``'s not-found path 404s for both
+                # missing and already-closed-evicted rows and never emits a
+                # 400 "No session". Kept as shared code rather than gated by
+                # caller — the branch is cheap and the symmetry makes future
+                # cascade verbs easier to add.
                 if result.get("status") == 400 and result.get("error") == "No session":
                     return cid, "skipped"
                 return cid, "failed"