plans: row 235 follow-up brief, the held grant-executor stubs stop when their test dir is gone

docs/plans/2026-10-20_host-credentials.md

@@ -121,3 +121,18 @@ tells Mos before row b lands.
 
 Gate: as row a, with section 10's row b tests and mutants, G27, G28 and the upsert mutant included, and
 the creative refusal tests and mutants (writer and spend).
+
+## Machine grant row b follow-up: the held stubs end with their test
+
+The row 197 r8 D5 proof stopped on a leftover process on 2026-10-21. In
+`packages/bus/tests/grant-executor.test.mjs`, the `add` stub waits for `release` when `hold-add`
+is set. G23 ("a revoke during install") and G13 write `release`, finish, and `t.after` removes the
+test dir. The stub polls every 50 ms, so it usually misses `release` and then loops forever on a
+dir that is gone. Four runs of the file on Sage's slot left 7 stubs, every run 37/0.
+
+Build: each hold loop in that file, `hold-add` and `hold-remove`, also stops when `$D` no longer
+exists. The test file is the only change. Nothing under `src` changes.
+
+Gate: Webby approves the commit. On Sage's gate the whole file passes three times in a row with no
+stub left, checked by pgrep on the run's TMPDIR, and the bus suite is green. A mutant that drops the
+dir check from `hold-add` leaves a stub behind.