Represent array holes independently from element storage with an optional runtime presence bitmap. Preserve hole state through length changes, deletion, slicing, concatenation, sorting, copying methods, iteration, serialization, and reference-counted cleanup while retaining packed-array fast paths.
Extend frontend lowering and IR validation for sparse literals, Array length construction, property-presence checks, delete, length assignment, and sparse appends. Add dense-array analysis so proven packed reads can use dedicated unchecked-presence runtime entry points in both native backends.
Add differential corpus coverage, runtime lifecycle tests, IR analysis tests, and compile fences for JavaScript fill loops that cannot prove complete initialization. Update affected binary-size expectations and align structuredClone transfer diagnostics with Node wording.
* Restore sandbox test performance
- Re-enable secure native compiler caching for repo-local test artifacts.
- Isolate strict cache coverage while keeping it off the sandbox critical path.
* fix: respect sandbox test runtime limits
* fix(compiler): refine narrowed union payload fields
- Treat pure union discriminant reads as stable within compound guards.
- Cover payload-field range refinement in analysis and library builds.
* fix(compiler): preserve field facts across union discriminants
- Classify Node 24 fetch APIs and options by static, dynamic-only, unsupported, and out-of-scope support.
- Project the inventory into the surface manifest and add runtime drift and conformance checks.
- Fence unprofiled Headers members with actionable SC2020 diagnostics.
- Pin the supported fetch surface to an explicit Node and Undici profile.
- Generate deterministic WebIDL, AbortSignal, and stream differential campaigns.
- Match Node stream pull scheduling while preserving typed source identity.
- Retain every declared path when structurally identical arms share a lowered record field.
- Keep differing-class collisions on SC4009 and cover both outcomes with regressions.
- Track ordinary record and class fields through stable guard expressions.
- Preserve conservative invalidation and add differential regression coverage.
- Track whether subscriptions_export is explicitly declared and reject dangling names at the profile.
- Preserve optional omission semantics and cover both paths with contract regressions.
- Preserve tagged-union shape identity when mapping synthesized payload fields into integer inference.
- Refuse fractional writes on named-union and message payload slots, with regressions for both paths.
Jimmy Miller