Windows: spawned console subprocesses flash visible windows that steal focus (windowsHide not set)

[PianoPrince]

Summary

When the DSH server runs without its own console (started detached / autostart), every subprocess it spawns gets a visible console window on Windows that steals foreground focus — most noticeably each pwsh -NoLogo -NoProfile -NonInteractive -Command … call from the PowerShell tool, plus another flash when the tree is killed via taskkill.

Node only allocates a visible console when the parent has no console and the spawn doesn't opt out, so this hits exactly the headless/detached setups.

Environment

• OS: Windows 11
• Package: @deepseek-ai/dsh@0.1.1-rc.2 (web mode)
• Launch: Popen([node, lib/bin.js, "web"], creationflags=DETACHED_PROCESS | CREATE_NEW_PROCESS_GROUP)

Root cause

Some packages already pass windowsHide: true (dsh-native-command, dsh-host-directory-picker-native), but the main executor paths don't:

1. @deepseek-ai/dsh-subprocess-local/lib/index.js ← main one
   • spawnSubprocess() — hot path for the pwsh/bash tools, LSP stdio, terminals, sandbox runner
   • taskkillTree() / taskkillProcessTree() — flashes on every teardown/timeout kill
   • DEFAULT_INTERNALS.exec — Windows process inspector
2. @deepseek-ai/dsh-web-app/lib/index.js — spawnBrowserLauncher()
3. @deepseek-ai/dsh/lib/plugin-*.js — spawnSync("pnpm", …)
4. @deepseek-ai/dsh-sandbox-local/lib/index.js — probe helpers

Suggested fix

Add windowsHide: true to those option objects (ignored on POSIX, safe unconditionally). Fixing it in LocalSubprocessRuntime's single spawn() site covers all shell/LSP/sandbox executors at once.

Verified locally on 0.1.1-rc.2: windows are gone, no change to stdio capture, tree termination, timeouts, or exit handling.

Happy to send a PR if helpful.

[Jstn-1g]

I put together a focused reference implementation for the central subprocess-local path, based on @PianoPrince's report:

• commit: Jstn-1g@88bd969
• branch: https://github.com/Jstn-1g/deepseek-harness/tree/reference/discussion-4231-windows-hidden-processes

It sets windowsHide: true on the managed child spawn() and both ordinary/PTY taskkill helpers. This covers the recurring PowerShell/Bash, LSP, sandbox-wrapped command, and teardown paths without changing argv, stdio, detachment, process ownership, or termination behavior.

This is intentionally a bounded fix, not a claim that every separate Web browser-helper, CLI, or probe launch site listed above has been swept.

Verification on Windows with Node 24.19:

• deterministic launch-boundary tests pin all three option objects while delegating to the real spawn/spawnSync
• new focused spawn.spec assertions: 2/2 passed
• windows-inspector.spec: 12/12 passed
• repository doc-sync: 28/28 passed
• full lint/build and pre-push typecheck passed
• independent diff review found no actionable issues

Thanks @PianoPrince for the clear report and local reproduction; the commit message credits Discussion #4231 explicitly.