Flutter MCP Automation Chain

The toolkit's surfaces are one chain, not competing products. The app registers ext.mcp.toolkit.* service extensions (mcp_toolkit), and every surface drives those same extensions through the universal AutomationDriver contract (universal_automation_interface, ADR-0038): observe (semantic snapshot with refs/bounds) → act (tap/type/navigate) → verify (snapshot again, read values). Agents learn one grammar regardless of the target — Flutter apps, browsers (CdpDriver), OS-native tiers.