deferred: T27 sweep test leaves two sleep 60 children; the fix is a process-group kill in both t.after hooks (row 251 landing d37210288, darkwing-0117, Dewey c30168)

docs/plans/DEFERRED.md

@@ -360,6 +360,22 @@ at every gate. Started 2026-09-12 during the control board MVP.
   do nothing yet. The row that adds the Console library routes decides
   whether the tester listener gets `library.sync`. Duckworth's view is
   that it shouldn't, because sync is a human write. (2026-10-21)
+- **T27 sweep test leaves two `sleep 60` children running.**
+  (Darkwing row 251 slot, darkwing-0113 and darkwing-0117; Dewey on
+  r2, comment 30168.) The sweep test spawns two detached shells,
+  `planted` at `host-run.test.mjs:528` and `decoy` at `:536`, each
+  running `sleep 60; :` with the run dir as `$0`. `sweepRunDir` kills
+  the planted shell by pid (`host-run.mjs:238`), and `t.after` kills
+  only the decoy shell. Neither kill reaches the `sleep` child, so each
+  one lives for up to 60 s after the test and trips any busy check that
+  follows. The fix is to kill the process group in both `t.after`
+  hooks: `process.kill(-pid, 'SIGKILL')`. Each shell is spawned
+  detached, so it leads its own group. `exec sleep 60` doesn't work.
+  The sweep matches the run dir in `/proc/<pid>/cmdline`
+  (`host-run.mjs:236`), and exec drops the `$0` that carries it, so the
+  planted process would survive and the "planted process killed" assert
+  would fail. This binds the next row that touches
+  `packages/bus/tests/host-run.test.mjs`. (2026-10-21)
 
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