Reactor Devtools — CLI-driven UI automation

The Reactor devtools let you look at a running debug-build app the way a user does (screenshots, rendered text, layout bounds) and drive it the way a user does (click, type, toggle, scroll). Always prefer the mur devtools CLI — every action composes with shell pipes and jq, each invocation is a complete audit record, and no MCP client setup is needed.

Under the hood the CLI talks JSON-RPC to a loopback HTTP endpoint the app exposes. The MCP endpoint is still available at http://127.0.0.1:PORT/mcp as a parity escape hatch, but reach for it only when the CLI can't express what you need (structured args the CLI flattens, or another MCP client that's already wired up).