fix(windows): suppress console flashes in env probes, lazy installs, and platform.win32_ver() (salvage #67690) - #70264
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…talls, and platform.win32_ver()
From windowless processes (the pythonw gateway and the kanban workers it
spawns), three spawn paths flash visible console windows on Windows:
1. tools/env_probe.py::_run() ran its interpreter/pip probes
(python3 / python / pip / 'python3 -m pip' / PEP-668 check, ~5 per
worker start) without creationflags — one console flash per probe.
2. tools/lazy_deps.py had four spawn sites with the same defect:
'uv pip install', the 'pip --version' probe, ensurepip, and the
pip install fallback.
Both now pass creationflags=windows_hide_flags() (CREATE_NO_WINDOW on
Windows, 0 on POSIX) — stdio capture still works because the child is
hidden, not detached.
3. CPython 3.11's platform.win32_ver() unconditionally calls
_syscmd_ver(), which runs 'cmd /c ver' via
subprocess.check_output(shell=True) with no window suppression. Any
dependency touching platform.uname()/version()/platform() at import
time flashes one 'cmd' window per windowless process. New helper
_subprocess_compat.suppress_platform_ver_console() (Windows-only,
never raises) stubs platform._syscmd_ver so win32_ver() falls back to
sys.getwindowsversion().platform_version — verified byte-identical
platform.platform() output on CPython 3.11
('Windows-10-10.0.26100-SP0' either way). Called at the top of
hermes_cli/main.py, right after the hermes_bootstrap guard, before
heavyweight imports.
Verified on Windows 11 by polling EnumWindows at ~15 ms and attributing
new visible HWNDs to the suspect process tree (conhost child presence is
NOT evidence of a visible window — it appears even with
CREATE_NO_WINDOW). Tests: tests/tools/test_windows_native_support.py,
test_env_probe.py, test_lazy_deps.py, test_lazy_deps_durable_target.py —
153 passed; the 3 failures are pre-existing on upstream/main in a
Windows environment (POSIX-only assertions and NTFS chmod semantics).
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
…run + add no-window tests (#67690 follow-up) Follow-up to the #67690 salvage (@m4r13y). The PR's tools/env_probe.py hunk was written against the old capture_output=True _run(); #67964/#67999 rewrote _run to temp-file capture on July 20, so that hunk no longer applied — but the rewritten _run still lacked creationflags and kept flashing one console per probe (~5 per kanban worker start) from windowless parents. Re-implement the one-line fix against the current shape: creationflags=windows_hide_flags() on the temp-file subprocess.run, preserving the #67964 grandchild-can't-wedge-the-pipe contract. Also add the tests the PR didn't ship, in tests/test_windows_subprocess_no_window_flags.py: - env_probe._run passes CREATE_NO_WINDOW and keeps temp-file (non-PIPE) stdout/stderr + DEVNULL stdin - lazy_deps uv install / pip --version probe / pip install fallback / ensurepip bootstrap all pass CREATE_NO_WINDOW - suppress_platform_ver_console: POSIX no-op (platform._syscmd_ver untouched, win32_ver() still returns), and simulated-Windows stubbing (echo stub installed, idempotent, never raises)
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Summary
Salvages PR #67690 by @m4r13y: suppresses the remaining Windows console flashes that fire regardless of launch topology — CPython 3.11/3.12's
platform.win32_ver()internally shells out tocmd /c verwith no window suppression (verified in the 3.11 stdlib; removed upstream in 3.13), plus four unflagged spawns intools/lazy_deps.pyand the env-probe runner.Changes
hermes_cli/_subprocess_compat.py: newsuppress_platform_ver_console()— forces the documented ValueError fallback sowin32_ver()readssys.getwindowsversion()instead of spawning; try/except-wrapped, POSIX no-ophermes_cli/main.py: early startup calltools/lazy_deps.py:creationflags=windows_hide_flags()on all 4 spawn sitestools/env_probe.py: one-line re-fit onto the rewritten temp-file_run([Bug]: Windows env probe can deadlock all new sessions when an orphaned pip child keeps capture pipes open #67964 contract preserved) — the PR's original hunk predated that rewrite (our follow-up commit)tests/test_windows_subprocess_no_window_flags.py: +6 mocked tests (ours; the PR shipped none)Validation
suppress_platform_ver_console()on Linuxplatform.win32_ver()unaffectedAuthorship preserved via cherry-pick (env_probe conflict resolved by dropping only the stale hunk from their commit); rebase-merge.
Closes #67690.
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