True when some live worker's codec is warm (a decode may be offloaded); the remaining cold workers are then warmed too. Otherwise starts warming ONE worker, if none is already warming, and returns false (decode locally).
Whether entry's codec is warm. A decode goes only to such a worker: one
still WARMING is downloading the codec chunk / compiling its WASM — tens to
hundreds of ms — for a chunk the main thread decodes in about one.
PrivatestateA worker without the task (a test double, a legacy worker) needs no warm-up.
PrivatewarmPrivatestart
Keyed by the instance, so an evicted or replaced worker starts cold.