# Starting point: FE engineer, postMessage after Workers / BC / structured clone

Learner is a frontend engineer with Web Workers (including dedicated `postMessage` + transfer), BroadcastChannel (same-origin pub/sub, no origin parameter), and Structured Clone (type matrix + transfer list) complete in this repo. Goal (issue #15) is durable judgment for **window/iframe/popup messaging and MessageChannel**, not a worker tutorial and not a security-audit course. First ZPD lesson: make the **WindowProxy / mailbox / origin-stamp** model click with a live lab — do not open on another “when X fits” spectrum they already have pieces of.