v0.63.0

v0.63.0

A conformance-and-infrastructure release. Standalone (pure-Wasm) test262 conformance jumped +2,495 tests, host gained +433, and the CI baseline/regression pipeline was structurally hardened after a drift bug had been silently misattributing regressions to innocent PRs.

test262 conformance

• Host (JS-host lane): 65.6% — 28,294 / 43,106
• Standalone (pure Wasm, no JS runtime): 63.5% — 27,378 / 43,106 (+2,495), narrowing the host↔standalone gap to ~916 tests.

Compiler / language

• Parameter-inference soundness fix (#3471): a polymorphic comparator param (isSameValue) was unsoundly narrowed to f64, corrupting string comparisons and cascading into ~433 name/length failures — the body-usage fallback now only applies to functions with zero call sites. (+433 host)
• BigInt64Array / BigUint64Array typed arrays (#838).
• Host-lane generator declarations route native — lazy §27.5 semantics with two-way next(v) (#3032).
• Object.is (SameValue) as a first-class standalone value (#2963).
• Dead-binding elision — shim-only standalone tests now compile host-free, a major standalone lever (#3362).
• Harness-prelude shim-leak fix (#3426) and harness-include dedup (#3427).

CI / infrastructure

• Baseline-drift structural fix (#3467): the test262 regression gate now compares each PR against its real merge-base via per-SHA caches, eliminating the drift that was false-parking clean PRs.
• Net-aware / flap-tolerant regression gate (#3457): net-positive changes pass instead of tripping a raw ratio threshold on small-sample noise; trap-growth and genuine net regressions still hard-fail.
• Landing-page baseline auto-refresh (#3468): the committed conformance baseline now promotes on every queue merge, so the dashboard stays current.
• Release/publish hardening: auto-publish GitHub Release (#3386), jsr.json lockstep version bump (#3454), publish CI on Node 24 (#3453).

Lockstep version bump 0.62.0 → 0.63.0 (package.json + packages/js2wasm proxy).