The divi input of lit/content-create is refused with unsupported when lit/divi-insert is disabled or the Divi group is disabled or read-only (ExposurePolicy::allows as a cross-group gate, asked at execute time). content-create without divi keeps working. Adds a registrar test that read-only write tools are never registered, so execute-ability can't reach them either. Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01At3V6SjwbMe6eMzVGW3Hs7