tools/computer_use/tool.py keeps the CLI approval flow in module-globals:
_approval_callback plus the per-session unlock stores _always_allow /
_session_auto_approve. Any test that installs a callback (or drives CLI
init far enough that the real one is registered) and does not reset it
poisons every later computer-use test in the same process:
* a leaked callback that raises — dead UI infra or a stale two-argument
signature (the contract is (action, args, summary)) — becomes
verdict='deny' in _request_approval, so dispatch tests fail with an
empty backend call list;
* a leaked callback that blocks (the real CLI one waits on an answer
queue) hangs a single-process run forever.
Both are order-dependent: tests/tools/test_computer_use.py passes 220/220
in isolation but shows dispatch failures in single-process full-suite runs
(and, with a blocking leak, a permanent hang observed via py-spy inside
_request_approval -> callback -> queue.get with no timeout).
Fix: an autouse teardown-only fixture resets callback + unlock stores
after every test; tests that install their own callback keep it for their
own duration. Regression pair included: a 'forgetful' test leaves a stale
two-arg callback behind, the next test asserts dispatch still routes to
the backend — red without the fixture (1 failed), green with it (225
passed together with the whole computer-use file).
