The assistant execution target tests deleted their temp HOME/workspace
dirs with a raw recursive delete in addTearDown. A background flush
(e.g. controller dispose still persisting state) can keep writing into
the dir while the delete walks it, so the delete races and fails with
"Directory not empty" (errno 39), failing the test on CI.
Route all unguarded teardown deletes through the existing
_resilientDelete helper (re-check existence + retry), and harden that
helper so its final fallback never re-throws — a temp-dir cleanup
failure must never fail a test.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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