# Implicit port and choose/reject

The learner can treat a dedicated worker’s implicit port as an already-enabled pipe (no `start()`, no `targetOrigin`), mint a pair only for a second stream, and choose or reject MessageChannel against a window hop, BroadcastChannel, a React callback, and that implicit port. That is now the floor: the next lesson can spend working memory on moving *both* ends so two iframes talk without parent on the pipe.

Evidence: the learner said they passed lesson 4 with every check correct.

Implications: issue #24’s remaining pattern is the sibling pipe — parent mints, transfers `port1` and `port2` into two iframes, and is no longer a party.