subprocess.run(["git", ...], timeout=...) deadlocks on Windows: run()'s
post-timeout cleanup calls an unbounded communicate() after killing git.
Killing the PATH-resolved launcher can leave a suspended descendant git.exe
holding duplicates of the captured stdout/stderr handles, so the pipes never
reach EOF and the reader-thread join blocks forever — leaking a process +
two reader threads per fired timeout (the accumulating git.exe load behind
Windows Defender CPU spikes).
Two fail-open probe call sites had this identical flaw:
- tui_gateway/git_probe.py::run_git — on the Desktop agent-build path
(_start_agent_build -> _session_info -> branch() -> run_git), where the
hang turned an optional branch label into "agent initialization timed
out" (#68609).
- agent/coding_context.py::_git — hangs the agent turn inside
build_coding_workspace_block under an ACP host (#66037).
Consolidate both onto one shared bounded_git_probe() in
hermes_cli/_subprocess_compat.py (both files already import from there, so
no new import surface):
- explicit communicate(timeout), then on ANY failure a tree-kill —
proc.kill() AND, on Windows, best-effort taskkill /T /F so the suspended
descendant that holds the pipe writers dies too — plus a bounded 1s
post-kill drain; if the pipes are still held they're abandoned (the
orphaned reader threads are daemonic and cost nothing).
- fail open to "" on every path: spawn error, timeout, kill() raising
(access denied / already reaped — a raise inside the except handler
previously escaped the contract), and non-timeout communicate() failures
now also terminate the child instead of leaving it running.
- the taskkill spawn can't re-enter the deadlock class: it captures no
pipes (DEVNULL), so its own timeout cleanup has no reader threads to join.
Normal-path spawn contract is preserved byte-for-byte: PIPE/PIPE/DEVNULL,
text + utf-8 errors="replace", hidden-window creationflags on Windows only,
nonzero returncode -> "". Each call site keeps its own timeout (1.5s / 2.5s).
Supersedes #68622 (Sora-bluesky — git_probe fix + tree-kill) and #66038
(iamwongeeeee — coding_context fix), folding both into one shared helper so
the two sites can't drift and every timeout tree-kills the descendant. Tests
consolidated onto the helper, incl. the previously-missing assertion that a
Windows timeout escalates to taskkill /T /F.
Co-authored-by: Sora-bluesky <sora.bluesky.dev@gmail.com>
Co-authored-by: iamwongeeeee <wykim777@naver.com>
Co-authored-by: Claude Fable 5 <noreply@anthropic.com>
The Windows desktop GUI runs its backend headless via pythonw.exe. Several
auxiliary subprocess sites that run inside that windowless backend spawned
console-subsystem children (git, gh, wmic, powershell, bash, rg, taskkill)
WITHOUT CREATE_NO_WINDOW, so Windows allocated a fresh conhost per call and
flashed a black window on screen — sometimes continuously (the dashboard
Projects-tree git probe alone fired ~118 spawns in 60s on startup).
The terminal tool, cron, browser, code_execution, and gateway-spawn paths
already carry windows_hide_flags(); these auxiliary probe/scan/launcher legs
were missed. Wire the existing helper into them:
- tui_gateway/git_probe.py: run_git (+ encoding=utf-8/errors=replace, fixes the
cp950 UnicodeDecodeError on CJK paths from the same site)
- agent/coding_context.py: _git (per-turn git status/log/diff)
- agent/context_references.py: _run_git + _rg_files (@file/@ref resolution)
- hermes_cli/copilot_auth.py: gh auth token probe (auxiliary provider:auto)
- hermes_cli/gateway.py: wmic + PowerShell Get-CimInstance PID scan
- hermes_cli/main.py: wmic stale-dashboard PID scan
- gateway/status.py: taskkill /T /F force-kill
windows_hide_flags() returns 0 on POSIX, so every changed call is a no-op on
Linux/macOS (verified: real git/rg probes still work; Windows-simulated calls
all pass creationflags=CREATE_NO_WINDOW).
Scoped to the windowless-backend paths that cause the reported flashing. The
Electron updater-handoff leg (main.cjs windowsHide:false) and the
interactive-CLI banner probes (cli.py) are intentionally NOT touched here —
the former needs a Windows-tested change of its own, the latter runs in a
visible console anyway.
Tracking: #54220
Refs: #53178#53631#53781#53957#49602#52982#53424#53053#53016
* fix(windows): stop terminal-window popups from background spawns
Native-Windows desktop/gateway users saw cmd/conhost windows flash on
gateway restart, image paste, the dashboard Projects tree, voice notes,
and ~5 min after closing the app (detached cron). Two root causes:
- Console-subsystem exes (taskkill, schtasks, wmic, netstat, tasklist,
agent-browser, git, ffmpeg, powershell, git-bash) spawned via raw
subprocess allocate a fresh console when the launching process has
none (pythonw desktop backend / detached gateway) - even with output
captured.
- uv venv pythonw shims re-exec console python.exe, so Python children
get a console regardless of how they're launched.
Fixes:
- Single hidden-spawn primitive (_subprocess_compat.run/.popen) that ORs
CREATE_NO_WINDOW on Windows, no-op on POSIX. Route every Hermes-owned
console-exe spawn through it.
- FreeConsole() catch-all in hermes_bootstrap: any Python child that
exclusively owns an auto-allocated console detaches it at startup
(GetConsoleProcessList()==1 gate leaves shared interactive consoles
untouched).
- Replace PowerShell/wmic gateway PID scans with in-process psutil.
- Skip schtasks queries on non-interactive desktop restarts.
- Prefer native agent-browser .exe over .cmd shims.
- Guard test bans raw subprocess spawns of the Windows-only console
tools repo-wide so the popup class can't regress.
* fix(windows): scope FreeConsole to background entry points; fix merge fallout
Console detach review (per #53810 feedback): GetConsoleProcessList()==1 can't
tell a uv pythonw->python phantom console apart from a user opening the
interactive CLI/TUI in its own fresh console (double-click, shortcut, ConPTY) —
both report a single attached process with a tty. Running FreeConsole() in the
import-time bootstrap therefore risked detaching a legitimately-interactive
terminal.
- Extract FreeConsole into explicit hermes_bootstrap.detach_orphan_console();
remove it from apply_windows_utf8_bootstrap() (import side effect).
- Call it only from known background mains: gateway run, dashboard backend
(start_server, what the desktop spawns), cron standalone, tui_gateway entry,
slash worker. Interactive CLI/TUI never calls it.
- Behavior-contract tests: frees only when solo owner, leaves shared console,
no-op without console / on POSIX, and asserts it's not an import side effect.
Merge fallout from origin/main (#53791):
- local.py: 3-way merge left a dangling **_popen_kwargs (NameError crashing
every terminal init). _subprocess_compat.popen already hides the window, so
drop it.
- discord adapter: merge stacked an undefined windows_hide_flags() onto the
primitive call; drop the redundant arg.
- test_gateway: scan now goes psutil-first (zero spawn); rewrite the
case-variant test to drive that production path.
* test(claw): mock _subprocess_compat.run seam for Windows process scan
claw.py's Windows tasklist/powershell scan routes through the hidden-spawn
primitive; the tests still patched claw_mod.subprocess, so on win32 the mock
was never hit and real spawns returned nothing. Patch the actual seam.
