[yusukebe]

HTTP checks miss client-side bugs. In a Void benchmark, no agent could check that a form clears after a submit, 1/5 apps in every condition shipped a delete that lands on /?delete, and agents reached for Chrome DevTools MCP or installed Playwright. hono browse loads the page in happy-dom, runs its JavaScript, and fills and clicks:

hono browse / --fill Title=milk --click 'button[type=submit]'

• Every request the page makes goes to the app like request and batch (app.request(), Vite, or workerd). No server, no Chrome. Redirects are followed; another origin gets 403.
• happy-dom is not a dependency. It resolves from the project, like vite, and is missing → HAPPY_DOM_NOT_FOUND. @babel/parser is loaded only by browse, so dist/cli.js stays the same size.
• happy-dom misreads a regex literal after !, ||, ?, - or return in a module. browse rewrites regex literals to new RegExp() until it is fixed upstream (report drafted, not filed yet).
• Vite's HMR client is replaced with a stub, since a one-shot run does not need HMR.

On the Void app it found both bugs: the form keeps its values after a submit, and the URL after a delete is /?delete. About 4 seconds a run. The experiment is in docs/agent-dx-log.md.

The author should do the following, if applicable

• Add tests
• Run tests
• pnpm run check:fix to format and lint the code
• Add TSDoc/JSDoc to document the code