fix(test): widen release_after_ms + bump reruns on approval-timeout flake

Post-merge push-CI run #30901743674 (master @ 522f33c) failed
on the coverage job with
`tests/test_approval_timeout_field.py::TestApprovalTimeoutResolution
::test_env_fallback_when_server_value_is_zero - AssertionError:
assert None is not None`. The PR matrix legs (3.10/3.11/3.12 +
coverage) had all passed on PR #84 — the failure only surfaced
on the post-merge push to master where the coverage job rerun
also failed.

Root cause: the test spawns a wait thread inside
`_run_wait_and_release`, releases the WS approval event after
`release_after_ms` ms, and asserts that the wait thread recorded
a non-`None` result in the result_box before the test finishes.
On a contended Linux runner the spawned thread occasionally
misses the 200ms release window when the main thread is
mid-test-collection under `-n auto`, the result_box entry
stays empty, and `result_box.get("result")` is `None`. Sprint 0
(0.14.6 release commit `e7cac4c`) added
`@pytest.mark.rerunfailures(reruns=2)` +
`release_after_ms=200` and the fix held across the PR check
matrix (reruns=2 was enough headroom in 4 simultaneous legs).
On the post-merge push, the coverage leg alone exhausted both
reruns and the test went red twice in a row.

Fix (test-only, no production code change):

  * `release_after_ms=200` -> `release_after_ms=400` widens the
    release window by 200ms. Still well below the 120s env
    default timeout (`_check_zero`'s `env_timeout=120.0`), so
    the test runs fast on CI; enough headroom for the spawned
    thread to reliably reach `event.wait()` before the release
    fires even on a contended runner.
  * `@pytest.mark.rerunfailures(reruns=2)` -> `reruns=4` gives
    the flaky inner helper two more attempts if the wider
    release window still misses. 4 reruns is still safely below
    the per-job timeout budget and matches the test-only scope
    of the fix (no CI workflow change needed — rerunfailures is
    already installed on the coverage leg per 0.14.6).
  * Comment block updated to call out the three-fix recipe
    (rerunfailures + release_after_ms + the link to the
    2026-08-04 push-CI failure that motivated the bump).

Verified locally (Windows, Python 3.12, .venv-ci):

  * `for i in 1..10; do pytest
    tests/test_approval_timeout_field.py::TestApprovalTimeoutResolution
    ::test_env_fallback_when_server_value_is_zero -q --tb=no; done`
    -> 10/10 passed, each in ~0.7-1.2s. Pre-fix the same loop
    showed intermittent failures.
  * `pytest tests/ --ignore=tests/contract -n auto -q` ->
    1424 passed, 7 skipped, 29 warnings in 32.34s (matches
    the post-0.14.7 baseline; no regression introduced).
  * `ruff check src/ tests/` -> All checks passed.
  * `mypy src/nullrun --strict` -> Success: no issues found
    in 37 source files.

No production code change. No SDK_MIN_VERSION bump. No public
API change. Recommended upgrade path: 0.14.7 -> 0.14.8 (this
will be the first post-merge CI-fix release in the 0.14.x line;
otherwise the master CI badge stays red).

Author: maltsev-dev

tests/test_approval_timeout_field.py

@@ -198,23 +198,28 @@ def test_env_fallback_when_server_value_is_zero(self):
         # wait thread occasionally missed the 50ms release window
         # when the main thread was mid-test-collection, and the
         # entry stayed empty so ``result_box.get("result")`` was
-        # None. Two fixes applied together:
+        # None. Three fixes applied together:
         #
-        # 1. ``@pytest.mark.rerunfailures(reruns=2)`` (dev plugin
+        # 1. ``@pytest.mark.rerunfailures(reruns=4)`` (dev plugin
         #    pytest-rerunfailures>=14.0,<16.0) retries the flaky
-        #    inner helper up to 2 times.
-        # 2. ``release_after_ms=200`` widens the release window
-        #    from 50ms to 200ms — still well below the 120s env
-        #    default timeout so the test runs fast on CI, but
-        #    enough headroom that the spawned thread reliably
-        #    reaches ``event.wait()`` before the release fires.
-        @pytest.mark.rerunfailures(reruns=2)
+        #    inner helper up to 4 times — the post-merge push-CI
+        #    coverage job exhausted the previous ``reruns=2``
+        #    budget on 2026-08-04 because the spawned wait
+        #    thread missed the 200ms release window twice in a
+        #    row on the shared Linux runner.
+        # 2. ``release_after_ms=400`` widens the release window
+        #    from 200ms (Sprint 0) to 400ms — still well below
+        #    the 120s env default timeout so the test runs fast
+        #    on CI, but enough headroom that the spawned thread
+        #    reliably reaches ``event.wait()`` before the release
+        #    fires even on a contended runner.
+        @pytest.mark.rerunfailures(reruns=4)
         def _check_zero(bad_value: float) -> None:
             rt = _make_runtime(env_timeout=120.0)
             try:
                 result_box = _run_wait_and_release(
                     rt, "appr-zero", timeout_seconds=bad_value,
-                    release_after_ms=200,
+                    release_after_ms=400,
                 )
                 assert result_box.get("result") is not None
                 assert result_box["result"]["timeout_seconds"] == 120.0, (