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
When Hermes runs in TUI mode, the gateway child process communicates with
the Node.js parent over a JSON-RPC protocol on stdin. Subprocess calls that
inherit this stdin fd can trigger a race condition where the child's stdin
read returns EOF, causing the gateway to exit cleanly (exit code 0) mid-tool-
execution.
This is the same root cause as issue #14036 (byterover plugin) and PR #39257
(SSH environment backend). This commit applies the fix — stdin=subprocess.DEVNULL
— to all 85 subprocess.run() and subprocess.Popen() calls that execute inside
the TUI gateway child process.
Scope: TUI-context code only (agent/, tools/, plugins/, tui_gateway/server.py).
CLI code (cli.py, hermes_cli/), tests, scripts, and gateway process management
are excluded — they don't run inside the TUI child and inherit the terminal's
stdin, not the JSON-RPC pipe.
85 call sites across 28 files. All files pass syntax check.
