`[2026-07-06]` **Playwright: no python `playwright` module in the venv; use NODE playwright + an explicit `executablePath`.** Shared box browsers live at `/opt/ms-playwright` build **1223**; `npm i playwright` (latest) wants build **1228** -> "Executable doesn't exist" mismatch. Fix: `chromium.launch({ executablePath: '/opt/ms-playwright/chromium-1223/chrome-linux64/chrome' })` (+ `export PLAYWRIGHT_BROWSERS_PATH=/opt/ms-playwright`). A node script drives the SPA (pick agent -> open -> assert transcript). The Playwright DOM check is the only lens that catches SPA JS-render bugs — unit tests can't reach them.