Pieces run inside a Web Worker, so window.acSetLiveFocus / acSetLiveTrackColor defined in the piece were no-ops — they lived in the worker's global scope, not jweb's main-thread window where Max's executejavascript actually runs. And the piece was listening for e.is("blur") but disk.mjs dispatches focus-change as focus/defocus, so the event path never fired either. Bridge moved into bios.mjs (main thread, M4L-only): • window.acSetLiveFocus(N) → send({type:"focus-change", content:!!N}) → existing disk.mjs dispatch as e.is("focus")/e.is("defocus") • window.acSetLiveTrackColor(N) → send({type:"live:track-color", content:[r,g,b]}) → new disk.mjs dispatch as e.is("live:track-color") with e.trackColor • daw:request-focus / daw:request-track-color types forward to window.max.outlet so the piece can ask Max to re-emit post-boot Piece now uses e.is("defocus") (not "blur"), listens for e.is("live:track-color"), sends the re-request messages via send(), and drops all the worker-broken window/document code + poll.