fix(reactivity): proxy sealed and non-extensible targets (fix #14893)

[itsybitsybootsy]

Summary

reactive(Object.seal({...})) returned the raw target instead of a proxy, so mutations on existing keys went untracked. The guard in createReactiveObject skipped any non-extensible target, but seal and preventExtensions only lock the structure, not the values. Narrowed to Object.isFrozen. The broader guard was the fix for #1784 / #1753, back when reactive wrote a flag onto the target. That hasn't been true for a while.

markRaw can't put the SKIP flag onto a non-extensible target, so after the guard change it falls back to a side WeakSet for those.

Closes #14893.

Test Plan

pnpm vitest run packages/reactivity/ reports 434 passed. The new test exercises reactive, shallowReactive, readonly, and shallowReadonly on sealed inputs with effect tracking, and a separate test pins the markRaw WeakSet path. The freeze case is preserved as should not observe frozen objects.

Summary by CodeRabbit

• Tests

  • Added tests covering opt-out behavior for non-extensible objects (sealed/frozen/preventExtensions), nested cases, shallow/react variants, and watch traversal skipping opt-out targets.

• Bug Fixes

  • Improved opt-out handling so non-extensible objects are correctly ignored by reactivity where intended.
  • Clarified behavior for frozen vs. sealed/preventExtensions targets when nested, ensuring correct dependency tracking.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

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📥 Commits

Reviewing files that changed from the base of the PR and between 637360b and 5aa8967.

📒 Files selected for processing (3)

• packages/reactivity/__tests__/reactive.spec.ts
• packages/reactivity/src/reactive.ts
• packages/reactivity/src/watch.ts

🚧 Files skipped from review as they are similar to previous changes (1)

• packages/reactivity/tests/reactive.spec.ts

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📝 Walkthrough

Walkthrough

This PR adds a WeakSet-based fallback for markRaw to opt out non-extensible objects, exports isRawMarked, updates createReactiveObject to skip frozen or raw-marked targets, updates watch traversal to respect isRawMarked, and adds tests for sealed, frozen, and prevented-extension behaviors.

Changes

rawSet-based raw target tracking for non-extensible objects

Layer / File(s)	Summary
rawSet, isRawMarked and markRaw integration packages/reactivity/src/reactive.ts	Introduces internal rawSet WeakSet and exported isRawMarked. markRaw records non-extensible targets in rawSet when SKIP cannot be defined. createReactiveObject returns early for isRawMarked(target) or Object.isFrozen(target).
watch traversal update packages/reactivity/src/watch.ts	Replaces ReactiveFlags.SKIP checks with isRawMarked(value) to stop deep traversal and updates imports accordingly.
Test coverage for markRaw and non-extensible behavior packages/reactivity/__tests__/reactive.spec.ts	Adds tests asserting markRaw preserves opt-out for sealed objects (including nested cases), verifies watch traversal skips marked non-extensible targets, asserts frozen nested objects are not made reactive, and updates expectations for sealed/preventExtensions targets across shallow/react/readonly variants.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Possibly related issues

• reactive silently skips un-extensible objects, which seems undocumented and unnecessary #14893 — The change matches this issue's objective of not silently skipping non-extensible targets and adding rawSet/isRawMarked support.

Possibly related PRs

• vuejs/core#14860: Modifies similar createReactiveObject/markRaw early-return logic and overlaps with this PR.

Suggested labels

ready to merge

Suggested reviewers

• edison1105

Poem

🐰 I found a sealed and quiet thing,
A WeakSet stitch to clip its string,
markRaw whispers, "stay unchanged,"
traversal skips what couldn't be arranged,
A gentle hop; the reactivity bell won't ring.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 50.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and specifically summarizes the main change: fixing reactivity behavior for sealed and non-extensible targets, directly addressing issue #14893.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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• Create PR with unit tests

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[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@packages/reactivity/src/reactive.ts`:
- Around line 26-27: The parity issue: non-extensible markRaw values stored in
rawSet are not being treated the same as objects flagged with ReactiveFlags.SKIP
during deep traversal/dependency collection (e.g., inside watch()). Fix by
updating the traversal / dependency-collection checks that currently test for
ReactiveFlags.SKIP to also check rawSet.has(target) (and where appropriate check
for non-extensible via Object.isExtensible) so markRaw non-extensible objects
are skipped the same way; update all places that gate behavior on
ReactiveFlags.SKIP (search for uses in watch() and traversal helpers) to include
a combined condition like “isSkipped = !!target[ReactiveFlags.SKIP] ||
rawSet.has(target)” so sealed/marked objects behave identically to skip-flagged
ones.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

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ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: b31663a2-de15-42b8-89cb-1dda094358a6

📥 Commits

Reviewing files that changed from the base of the PR and between 86ad076 and 637360b.

📒 Files selected for processing (2)

• packages/reactivity/__tests__/reactive.spec.ts
• packages/reactivity/src/reactive.ts