A Client plugin loaded after the page starts fetches its bootstrap once. The Host now registers that route before starting the Worker and answers once the Worker is ready, so enabling Developer Tools on a running page opens the bottom DevTools without a reload. A failed start answers 503.
When the platform cannot run the Worker (ERR_FEATURE_UNAVAILABLE_ON_PLATFORM), the Host warns once and stays active with only the 503 bootstrap route; serve-static and open load after the Worker starts. Every other startup failure still fails the fiber.
imccyu
bf1a2bf69c