Backport #3372: fix(core): preserve new.target in the deterministic Date override so Date subclasses work - #3434
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… so `Date` subclasses work (#3372) * test: add failing test for Date subclassing in workflow VM Co-Authored-By: Claude Fable 5 <noreply@anthropic.com> Signed-off-by: ar_tama <arata.makoto@gmail.com> * fix(core): preserve `new.target` in the deterministic `Date` override so `Date` subclasses work in workflow functions The VM's `Date` override was a plain function, so `class X extends Date` lost the subclass identity: `super()` returned a fresh plain `Date` that became `this`, dropping the subclass's methods and fields. This silently broke `Date` subclasses like `TZDate` from `@date-fns/tz`. Using `class Date extends Date_` keeps `new.target` intact, and `extends` already wires up the prototype chain and statics, so the manual `prototype` assignment and `Object.setPrototypeOf` fix-ups are no longer needed. Determinism is unchanged: zero-arg construction still returns the fixed timestamp and `Date.now()` is still overridden. Fixes #3371 Co-Authored-By: Claude Fable 5 <noreply@anthropic.com> Signed-off-by: ar_tama <arata.makoto@gmail.com> * test: add failing test for calling `Date()` without `new` Co-Authored-By: Claude Fable 5 <noreply@anthropic.com> Signed-off-by: ar_tama <arata.makoto@gmail.com> * fix(core): keep `Date()` callable without `new` Use a plain function that branches on `new.target` and constructs via `Reflect.construct(Date_, args, new.target)` instead of a class: subclassing still works (`new.target` is forwarded), and calling `Date()` without `new` now matches the spec — arguments are ignored and the (fixed) time string is returned, where the previous override returned a `Date` object. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com> Signed-off-by: ar_tama <arata.makoto@gmail.com> * chore: update changeset to match the final `Reflect.construct` implementation Co-Authored-By: Claude Fable 5 <noreply@anthropic.com> Signed-off-by: ar_tama <arata.makoto@gmail.com> --------- Signed-off-by: ar_tama <arata.makoto@gmail.com> Co-authored-by: Claude Fable 5 <noreply@anthropic.com> Signed-off-by: Makoto Arata <arata.makoto@gmail.com>
🦋 Changeset detectedLatest commit: b001f67 The changes in this PR will be included in the next version bump. This PR includes changesets to release 16 packages
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VaguelySerious
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Aug 10, 2026
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🧪 E2E Test Results❌ Some tests failed Summary
❌ Failed Tests🌍 Community Worlds (102 failed)redis (19 failed):
turso (83 failed):
Details by Category✅ ▲ Vercel Production
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TooTallNate
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Automated backport of #3372 to
stable(backport job run).AI recommendation: This is a correctness fix for a silent data bug: the VM's deterministic
Dateoverride droppednew.target, soDatesubclasses (e.g.TZDatefrom@date-fns/tz) lost their identity, methods, and fields inside workflow bodies. The buggy override exists verbatim onstable(packages/core/src/vm/index.tslines 33-45), the change is apatchscoped to that file plus tests, and determinism is unchanged. The one behavior change —Date()withoutnewnow returns the time string per spec instead of aDateobject — is a spec-conformance correction that is part of the same fix, not new functionality.