Represent ordinary JavaScript arrays with hole, value, and explicit-undefined states; add sparse side storage and carry missing values through the frontend, native backends, runtime, and Node-facing consumers.
- Shard portable coverage across 16 sandboxes while retaining focused Darwin contracts.
- Run invariant suites once and keep differential and sanitizer-sensitive coverage in both lanes.
- Harden sandbox transport, exit-status parsing, and Linux runtime test portability.
Chris Tate