# GH#20599 — Phase A: rt_version + greeting-cache-helper foundation

Worker-ready issue body at https://github.com/marcusquinn/aidevops/issues/20599

Child of #20471 (Phase A). See issue body for full implementation context.

## Files Scope

- `.agents/scripts/runtime-registry.sh`
- `.agents/scripts/greeting-cache-helper.sh`
- `tests/test-runtime-registry.sh`
