- shared_memory.rs: global registry of Arc<SharedBuffer> (Mutex+Condvar) keyed by u64 ID - SharedArrayBuffer constructor: allocates a shared buffer, stores ID as __sab_id__ - Int32Array constructor: view over SharedArrayBuffer or standalone (also backed by SAB) - Atomics object: load, store, add, sub, and, or, xor, exchange, compareExchange, wait, notify all operations go through the shared buffer registry for cross-thread visibility - structured_clone: TAG_SHARED_ARRAY_BUFFER transfers by ID only (Arc-clone semantics) - importScripts: fetches scripts synchronously, queues them in thread-local IMPORT_QUEUE, drained by run_worker_script after each vm.execute() call - fetch.rs: fetch_text_sync() helper for importScripts synchronous fetch - 13 new Atomics/SAB unit tests + 4 shared_memory tests, all passing Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>