- Run the production LLVM backend natively and reproduce its output across compiler generations.
- Replace unchecked emitter contexts with explicit shared state and callback hosts.
- Preserve NaN in serialized IR and respect optional record storage during spreads.
- Compile the production validator and exercise native IR construction and validation on C and LLVM.
- Preserve Error causes, wider callbacks, and discriminated JSON layouts in static programs.
- Version the IR and runtime ABI and cover the new compiler paths with differential and sanitizer tests.
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.