Modern JS built-ins, and an honest look at where the whole thing stands: 50

Two ES2024 built-ins the surface was missing: Promise.withResolvers (a pending promise plus the resolve/reject functions that settle it, returned together - the same wiring `new Promise` does internally, now exposed so code can settle a promise from outside the executor), and String isWellFormed / toWellFormed. Both are tested through the JS surface. The bigger news is the overall figure: it moves from 48 to 50. That is a HOLISTIC judgment of how much of the web platform this engine covers, and it has now genuinely reached the halfway mark - not by moving any single aspect beyond what its tests prove, but because the nine releases shipped in this run added six real subsystems (a correct async/await resumable VM, native recursion, Web Audio synthesis and DSP, WebVTT captions, a DevTools Protocol that drives and mutates the page, an accessibility tree) plus authenticated AES-GCM, and weighed together that is honestly half a browser. The floors that keep it from climbing past 50 are named and real - no GPU compositor, no video codecs, no HTTP/2, no multi-process isolation - and each is a multi-session effort, which is exactly why 50 and not more.