fix(hmr): prevent __VUE_HMR_RUNTIME__ from being overwritten by vue runtime in 3rd-party libraries #13817

edison1105 · 2025-08-28T02:44:47Z

Summary by CodeRabbit

Bug Fixes
- Guarded installation of the HMR runtime to avoid overwriting an existing global instance, improving compatibility with tooling and custom-element environments and reducing development-time conflicts.
- Maintains existing HMR behavior and DEV-only gating; no changes to production builds or public APIs, preserving current integrations and surface compatibility.

…-party libraries

coderabbitai · 2025-08-28T02:44:54Z

Walkthrough

Introduces a guard before installing the HMR runtime onto the global object in packages/runtime-core/src/hmr.ts, avoiding overwriting an existing global HMR runtime. createRecord, rerender, and reload remain wrapped and exposed via HMRRuntime. No public API signatures changed; DEV gating and other HMR logic remain the same.

Changes

Cohort / File(s)	Summary
HMR runtime global guard `packages/runtime-core/src/hmr.ts`	Install HMR runtime on `globalThis` only if `globalThis.__VUE_HMR_RUNTIME__` is undefined; preserve existing runtime otherwise. Keep try-wrapped `createRecord`, `rerender`, `reload` exports; comments reference related issues; no API signature changes.

Sequence Diagram(s)

sequenceDiagram
  autonumber
  participant App as App Module
  participant HMR as HMR Module (hmr.ts)
  participant Global as globalThis

  App->>HMR: import hmr.ts (DEV)
  HMR->>Global: check __VUE_HMR_RUNTIME__
  alt not present
    HMR->>Global: assign { createRecord, rerender, reload }
    note right of Global #DFF0D8: New runtime installed
  else present
    HMR-->>Global: skip assignment (do not overwrite)
    note right of Global #FBEED5: Existing runtime preserved
  end
  App->>Global: call __VUE_HMR_RUNTIME__ methods

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Assessment against linked issues

Objective	Addressed	Explanation
Prevent HMR runtime overwrite that breaks HMR with webcomponents (#644)	✅

Possibly related PRs

fix(hmr): avoid hydration for hmr updating #12262 — Touches HMR runtime usage and interacts with the same global HMR surface; likely related to runtime installation and usage.

Suggested reviewers

Doctor-wu
LittleSound
KazariEX

Poem

I tap my paws on keys so light,
Guard the runtime, set it right.
No overwrite in moonlit glow,
Hot-reload hops along, let’s go!
— A happy hare, debugging with ease 🐇✨

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packages/runtime-core/src/hmr.ts (1 hunks)

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packages/runtime-core/src/hmr.ts

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github-actions · 2025-08-28T02:45:46Z

Size Report

Bundles

File	Size	Gzip	Brotli
runtime-dom.global.prod.js	101 kB	38.4 kB	34.6 kB
vue.global.prod.js	159 kB	58.5 kB	52.1 kB

Usages

Name	Size	Gzip	Brotli
createApp (CAPI only)	46.5 kB	18.2 kB	16.7 kB
createApp	54.5 kB	21.2 kB	19.4 kB
createSSRApp	58.7 kB	22.9 kB	20.9 kB
defineCustomElement	59.5 kB	22.8 kB	20.8 kB
overall	68.5 kB	26.4 kB	24 kB

pkg-pr-new · 2025-08-28T02:46:00Z

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commit: 7113d9c

coderabbitai

Actionable comments posted: 2

🧹 Nitpick comments (2)

packages/runtime-core/src/hmr.ts (2)
36-37: Nit: tighten comment wording

Minor grammar/clarity improvement.
-  // custom-element libraries bundle Vue to simplify usage outside Vue projects but
-  // it overwrite __VUE_HMR_RUNTIME__, causing HMR to break.
+  // Some custom-element libraries bundle Vue to simplify usage outside Vue projects,
+  // and they overwrite __VUE_HMR_RUNTIME__, causing HMR to break.
38-44: Robust existence check

Truthiness checks can be defeated by nulling out the property. Using hasOwnProperty (as in the refactor above) or in is safer.
-  if (!globalThis.__VUE_HMR_RUNTIME__) {
+  if (!Object.prototype.hasOwnProperty.call(globalObj, '__VUE_HMR_RUNTIME__')) {

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packages/runtime-core/src/hmr.ts (1 hunks)

🧰 Additional context used

🧬 Code graph analysis (1)

packages/runtime-core/src/hmr.ts (1)

packages/shared/src/general.ts (1)

getGlobalThis (188-202)

🪛 Biome (2.1.2)

packages/runtime-core/src/hmr.ts

[error] 34-34: Do not shadow the global "globalThis" property.

Consider renaming this variable. It's easy to confuse the origin of variables when they're named after a known global.

(lint/suspicious/noShadowRestrictedNames)

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🔇 Additional comments (1)

packages/runtime-core/src/hmr.ts (1)
34-44: Use browser console for HMR runtime overwrite test
The shell script failed because console.log is JS, not shell. Please paste and run the following in your browser’s dev console:
console.log('__VUE_HMR_RUNTIME__ before:', globalThis.__VUE_HMR_RUNTIME__);
globalThis.__VUE_HMR_RUNTIME__ = { hijacked: true };
console.log('__VUE_HMR_RUNTIME__ after:', globalThis.__VUE_HMR_RUNTIME__);
Expected: the second log still shows the original HMR runtime object, not { hijacked: true }.

packages/runtime-core/src/hmr.ts

edison1105 · 2025-09-02T09:00:51Z

/ecosystem-ci run

vue-bot · 2025-09-02T09:08:19Z

📝 Ran ecosystem CI: Open

suite	result	latest scheduled
language-tools	✅ success	✅ success
quasar	✅ success	✅ success
pinia	✅ success	✅ success
router	✅ success	✅ success
radix-vue	✅ success	✅ success
nuxt	✅ success	✅ success
primevue	✅ success	✅ success
test-utils	✅ success	✅ success
vite-plugin-vue	✅ success	✅ success
vant	✅ success	❌ failure
vitepress	✅ success	✅ success
vuetify	✅ success	✅ success
vue-i18n	✅ success	✅ success
vueuse	✅ success	✅ success
vue-simple-compiler	✅ success	✅ success
vue-macros	❌ failure	❌ failure

fix(hmr): prevent __VUE_HMR_RUNTIME__ from being overwritten by third…

3e58744

…-party libraries

edison1105 added ready to merge The PR is ready to be merged. scope: hmr 🔨 p3-minor-bug Priority 3: this fixes a bug, but is an edge case that only affects very specific usage. labels Aug 28, 2025

coderabbitai bot reviewed Aug 28, 2025

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edison1105 mentioned this pull request Aug 28, 2025

HMR is not working when import a WebComponent vitejs/vite-plugin-vue#644

Closed

7 tasks

edison1105 changed the title ~~fix(hmr): prevent __VUE_HMR_RUNTIME__ from being overwritten by 3rd-party libraries~~ fix(hmr): prevent __VUE_HMR_RUNTIME__ from being overwritten by vue runtime in 3rd-party libraries Aug 28, 2025

chore: tweaks

7113d9c

edison1105 merged commit 1392734 into main Sep 2, 2025
16 checks passed

edison1105 deleted the edison/fix/hmrOverride branch September 2, 2025 09:10

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fix(hmr): prevent __VUE_HMR_RUNTIME__ from being overwritten by vue runtime in 3rd-party libraries #13817

fix(hmr): prevent __VUE_HMR_RUNTIME__ from being overwritten by vue runtime in 3rd-party libraries #13817

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fix(hmr): prevent __VUE_HMR_RUNTIME__ from being overwritten by vue runtime in 3rd-party libraries #13817

fix(hmr): prevent __VUE_HMR_RUNTIME__ from being overwritten by vue runtime in 3rd-party libraries #13817

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