Hoist releasedBy/whenAborted — duplicated verbatim between start-temporal and start-amqp

[btravers]

From the 2026-08-13 repo audit.

releasedBy and whenAborted are duplicated verbatim between packages/start-temporal/src/temporal-runtime.ts:166-179 and packages/start-amqp/src/amqp-runtime.ts:165-178 — identical bodies, divergent TSDoc. Any runtime whose Serving.drain must honour the kernel's deadline AbortSignal will need them; a third runtime will copy them again.

Two copies is the last cheap moment to hoist.

Acceptance

• The pair lives once — in @btravstack/start (as part of the runtime-author toolkit next to the Runtime contract) or a shared internal — and both packages consume it.
• One TSDoc, kept where the code is.

[btravers]

Re-checked against main at ce0671c (2026-08-16). Still valid, unchanged. Package names in the issue predate the rename.

whenAborted and releasedBy are still duplicated verbatim:

• packages/temporal/src/temporal-runtime.ts — releasedBy / whenAborted at the file's tail
• packages/amqp/src/amqp-runtime.ts — identical bodies

Two things worth adding since the issue was written:

1. The kernel now has the same shape a third time, in a place the hoist would not cover: packages/core/src/drain.ts races its own timeout against the runtime having stopped, and packages/core/src/clock.ts's systemClock.sleep carries the abort-listener-plus-clearTimeout dance. If the pair is hoisted into @btravstack/core as runtime-author toolkit (the issue's first option), it should be checked against Clock.sleep first — there may be one primitive here, not two.
2. @btravstack/testing's createFakeClock also implements abort-cuts-the-wait so the kernel's skip signal works under a fake clock. Any hoisted primitive has to stay Clock-agnostic or the harness diverges from production.

Still the right call, and still cheap: two copies, no third consumer yet.