Covers the browser preview bridge: picking the agent's current tab, translating human input into browser commands (dropping malformed or non-web input), serving the stream with the last frame on connect and repeats for still pages, following tab switches, announcing real page changes only, binding to loopback, and surviving a browser that stops answering.

## Before writing SPEC.md files

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