Run Vitest in the browser shell

[vanilla-wave]

Goal

Run Vitest 4.1.11 with Vite 8.0.16 in the browser shell on both forks and threads pools. Preserve TypeScript config/tests, reporter output, and Node exit codes.

Delivered so far

• npm exact-version overrides installs the real Vitest/Vite tree in Chromium.
• node:path/posix, process named imports, and importable loud builtin members unblock module linking.
• Symbol-key loader guards, process stdio pipe behavior, advanced child IPC, and VM script offsets are implemented with Node parity and targeted regression tests.
• Compatibility pages name the unsupported calls.

Evidence

• pnpm pr:check: 25/25 green at the accepted first-four-slice checkpoint; current branch awaits the next full gate.
• Chromium install and VM-offset e2e: green on committed revisions.
• Full Vitest run e2e is RED on the current branch: empty output, exit 0 before config loading.

Remaining

Process/Worker lifecycle, Worker stdio, both Vitest pools, full reporter/exit-code acceptance, and final full gate/review. PR stays draft until the goal is green.

[github-actions]

Netlify preview: https://pr-352--rifty-playground.netlify.app
Immutable deploy: https://pr-352--rifty-playground.netlify.app
Deploy logs: https://app.netlify.com/projects/rifty-playground/deploys/6ab348c36f7514cde5f49c08

[vanilla-wave]

Closed after a comparative review of the four vitest-run-in-browser attempts (#349, #351, #352, #353): #351 continues as the base. Review artifacts kept locally.