Use primordials for extensions/timers

Editor assessment

The subject states the pattern application exactly: primordials are used in extensions/timers. For readers following the primordials effort the intent (sandbox-safe builtins) is clear, but the message never states that rationale, and the scope is conveyed only by the path fragment. Type refactor is accurate. No body explains why the timers extension needed the treatment, and no footers appear. Understandable within the effort's context, thin outside it.