fix(windows): detach child process to prevent taskkill /F /IM node.exe from killing opencode

[Sanjay-doppalapudi]

Issue for this PR

Closes #25930

Type of change

• Bug fix
• New feature
• Refactor / code improvement
• Documentation

What does this PR do?

On Windows, when OpenCode is installed via npm, the bin/opencode launcher is a Node.js script that uses childProcess.spawnSync() to run the compiled opencode.exe binary. Because spawnSync is synchronous, the node.exe process stays alive as a blocking parent of opencode.exe for the entire session. Running taskkill /F /IM node.exe (or similar) kills the node launcher, which also brings down opencode.exe.

This fixes it by switching from spawnSync to spawn with detached: true and explicit stdio handles ([0, 1, 2]). The child process now runs in its own process group, so force-killing node.exe no longer cascades to opencode.exe.

Note: PR #25762 addresses a related but different aspect — it adds prompt/runtime guards to prevent the AI from issuing these commands. This PR fixes the underlying process architecture so that even if the commands are run (by the user manually, or any other scenario), OpenCode survives.

How did you verify your code works?

• node --check confirms the launcher script is syntactically valid
• bun run dev launches OpenCode correctly — TUI renders, console output works
• Tested the patched launcher with the npm-installed version: OpenCode stays alive after running taskkill /F /IM node.exe in a separate terminal
• Exit codes propagate correctly when OpenCode exits normally

Screenshots / recordings

N/A — no UI changes.

Checklist

• I have tested my changes locally
• I have not included unrelated changes in this PR

[github-actions]

The following comment was made by an LLM, it may be inaccurate:

Potential Related PR Found:

• PR fix: prevent shell commands from killing all Node.js processes #25762: "fix: prevent shell commands from killing all Node.js processes"
  • URL: fix: prevent shell commands from killing all Node.js processes #25762
  • Why it's related: This PR appears to address a similar issue regarding Node.js processes being killed unexpectedly. However, PR fix(windows): detach child process to prevent taskkill /F /IM node.exe from killing opencode #26127 (the current PR) is specifically about preventing taskkill /F /IM node.exe from killing the OpenCode process by using detach: true in the Windows launcher, while fix: prevent shell commands from killing all Node.js processes #25762 seems to focus on preventing shell commands from killing Node.js processes more broadly. They may be related efforts but address the problem at different levels.

[github-actions]

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