fix: CLI fails to start on Windows with process.execve unavailable

[elkaix]

Related Issue

No linked issue — problem explained below.

Problem

On Windows, pythinker installed via npm fails immediately:

Failed to start Pythinker Code: The feature process.execve is unavailable on the current platform, which is being used to run Node.js

Windows Node defines process.execve as a function that throws ERR_FEATURE_UNAVAILABLE_ON_PLATFORM when called. The launcher's existence check (process.execve !== undefined) therefore routed Windows into the execve path and crashed before the existing spawn fallback could run.

What changed

The launcher checks the platform first: win32 always uses the spawn fallback; the execve path (which preserves pid, process group, and controlling terminal) remains for POSIX. Added a regression test that fakes win32 with a throwing execve and asserts the fallback child completes — verified it fails against the previous launcher.

Checklist

• I have read the CONTRIBUTING document.
• I have linked a related issue, or explained the problem above.
• I have added tests that prove my feature works.
• Ran gen-changesets skill, or this PR needs no changeset.
• Ran gen-docs skill, or this PR needs no doc update.

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📥 Commits

Reviewing files that changed from the base of the PR and between d396320 and f6aeffa.

📒 Files selected for processing (5)

• .agents/skills/gen-docs/SKILL.md
• .agents/skills/sync-changelog/SKILL.md
• .changeset/windows-launcher-execve.md
• apps/pythinker-code/src/launcher.ts
• apps/pythinker-code/test/cli/ffi-launcher.test.ts

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[pkg-pr-new]

pnpm dlx https://pkg.pr.new/@pythoughts/pythinker-code@f6aeffa

npx https://pkg.pr.new/@pythoughts/pythinker-code@f6aeffa

commit: f6aeffa