Covers launching the run's shared browser: the remote-control launch on a throwaway profile, finding a browser (override, well-known paths, PATH) against an injected filesystem, waiting for the port with a bounded timeout, giving up cleanly when no browser exists or never listens, and pointing the agent's browser tools at the shared instance only when one was launched.

## Before writing SPEC.md files

Read https://raw.githubusercontent.com/brillout/sdd/refs/heads/main/sdd.md
