vuejs · edison1105 · May 6, 2026 · May 4, 2026 · May 6, 2026
diff --git a/packages/reactivity/src/effect.ts b/packages/reactivity/src/effect.ts
@@ -114,8 +114,19 @@ export class ReactiveEffect<T = any>
   onTrigger?: (event: DebuggerEvent) => void
 
   constructor(public fn: () => T) {
-    if (activeEffectScope && activeEffectScope.active) {
-      activeEffectScope.effects.push(this)
+    if (activeEffectScope) {
+      if (activeEffectScope.active) {
+        activeEffectScope.effects.push(this)
+      } else {
+        // The active scope has already been stopped. This happens when a
+        // component's setup is resumed after a top-level `await` (via the
+        // compiler-emitted `__restore()` from `withAsyncContext`) but the
+        // component was unmounted while pending under <Suspense>. Without
+        // this guard the effect would become an orphan: not held by any
+        // scope (so it cannot be stopped via the scope chain) yet still
+        // able to subscribe to reactive deps and fire forever.
+        this.flags &= ~EffectFlags.ACTIVE
+      }
     }
   }
 

diff --git a/packages/reactivity/src/effectScope.ts b/packages/reactivity/src/effectScope.ts
@@ -22,6 +22,7 @@ export class EffectScope {
   cleanups: (() => void)[] = []
 
   private _isPaused = false
+  private _warnOnRun = true
 
   /**
    * only assigned by undetached scope
@@ -44,12 +45,19 @@ export class EffectScope {
   // TODO isolatedDeclarations ReactiveFlags.SKIP
 
   constructor(public detached = false) {
-    this.parent = activeEffectScope
     if (!detached && activeEffectScope) {
-      this.index =
-        (activeEffectScope.scopes || (activeEffectScope.scopes = [])).push(
-          this,
-        ) - 1
+      if (activeEffectScope.active) {
+        this.parent = activeEffectScope
+        this.index =
+          (activeEffectScope.scopes || (activeEffectScope.scopes = [])).push(
+            this,
+          ) - 1
+      } else {
+        // The parent scope has already stopped, so this child must not become
+        // a detached live scope.
+        this._active = false
+        this._warnOnRun = false
+      }
     }
   }
 
@@ -101,7 +109,7 @@ export class EffectScope {
       } finally {
         activeEffectScope = currentEffectScope
       }
-    } else if (__DEV__) {
+    } else if (__DEV__ && this._warnOnRun) {
       warn(`cannot run an inactive effect scope.`)
     }
   }

diff --git a/packages/runtime-core/__tests__/components/Suspense.spec.ts b/packages/runtime-core/__tests__/components/Suspense.spec.ts
@@ -12,6 +12,7 @@ import {
   createBlock,
   createCommentVNode,
   createElementBlock,
+  getCurrentInstance,
   h,
   nextTick,
   nodeOps,
@@ -29,13 +30,15 @@ import {
   shallowRef,
   watch,
   watchEffect,
+  withAsyncContext,
   withDirectives,
 } from '@vue/runtime-test'
 import {
   computed,
   createApp,
   defineAsyncComponent as defineAsyncComp,
   defineComponent,
+  effectScope,
   inject,
   provide,
 } from 'vue'
@@ -3009,4 +3012,217 @@ describe('Suspense', () => {
       expect(unmounted).toHaveBeenCalledTimes(1)
     })
   })
+
+  describe('async setup with top-level await', () => {
+    test('pending branch replaced before async setup resolves', async () => {
+      const updateSpy = vi.fn()
+      const stateRef = ref(0)
+      let resolvePending!: (v?: unknown) => void
+
+      const SlowComp = defineComponent({
+        async setup() {
+          let __temp: any, __restore: any
+          ;[__temp, __restore] = withAsyncContext(
+            () =>
+              new Promise(r => {
+                resolvePending = r
+              }),
+          )
+          __temp = await __temp
+          __restore()
+
+          watch(stateRef, updateSpy)
+
+          return () => h('div', 'slow')
+        },
+      })
+
+      const FillerComp = defineComponent({
+        setup: () => () => h('div', 'filler'),
+      })
+
+      const view = shallowRef<any>(SlowComp)
+      const Comp = defineComponent({
+        setup: () => () =>
+          h(Suspense, null, {
+            default: h(view.value),
+            fallback: h('div', 'fallback'),
+          }),
+      })
+
+      const root = nodeOps.createElement('div')
+      render(h(Comp), root)
+      expect(serializeInner(root)).toBe(`<div>fallback</div>`)
+
+      view.value = FillerComp
+      await nextTick()
+      expect(serializeInner(root)).toBe(`<div>filler</div>`)
+
+      // wait a macro task tick for all micro ticks to resolve
+      resolvePending(undefined)
+      await new Promise(r => setTimeout(r))
+
+      stateRef.value++
+      await nextTick()
+      expect(updateSpy).not.toHaveBeenCalled()
+    })
+
+    test('boundary unmounted before async setup resolves', async () => {
+      const updateSpy = vi.fn()
+      const stateRef = ref(0)
+      let resolvePending!: (v?: unknown) => void
+
+      const SlowComp = defineComponent({
+        async setup() {
+          let __temp: any, __restore: any
+          ;[__temp, __restore] = withAsyncContext(
+            () =>
+              new Promise(r => {
+                resolvePending = r
+              }),
+          )
+          __temp = await __temp
+          __restore()
+
+          watch(stateRef, updateSpy)
+
+          return () => h('div', 'slow')
+        },
+      })
+
+      const root = nodeOps.createElement('div')
+      render(
+        h(() =>
+          h(Suspense, null, {
+            default: h(SlowComp),
+            fallback: h('div', 'fallback'),
+          }),
+        ),
+        root,
+      )
+      expect(serializeInner(root)).toBe(`<div>fallback</div>`)
+
+      render(null, root)
+
+      resolvePending(undefined)
+      await new Promise(r => setTimeout(r))
+
+      stateRef.value++
+      await nextTick()
+      expect(updateSpy).not.toHaveBeenCalled()
+    })
+
+    test('repeated branch replacement before async setup resolves', async () => {
+      const updateSpy = vi.fn()
+      const stateRef = ref(0)
+      const resolvers: Array<(v?: unknown) => void> = []
+
+      const SlowComp = defineComponent({
+        async setup() {
+          let __temp: any, __restore: any
+          ;[__temp, __restore] = withAsyncContext(
+            () =>
+              new Promise(r => {
+                resolvers.push(r)
+              }),
+          )
+          __temp = await __temp
+          __restore()
+
+          const uid = getCurrentInstance()!.uid
+          watch(stateRef, () => {
+            updateSpy(uid)
+          })
+
+          return () => h('div', 'slow')
+        },
+      })
+
+      const FillerComp = defineComponent({
+        setup: () => () => h('div', 'filler'),
+      })
+
+      const view = shallowRef<any>(FillerComp)
+      const Comp = defineComponent({
+        setup: () => () =>
+          h(Suspense, null, {
+            default: h(view.value),
+            fallback: h('div', 'fallback'),
+          }),
+      })
+
+      const root = nodeOps.createElement('div')
+      render(h(Comp), root)
+      expect(serializeInner(root)).toBe(`<div>filler</div>`)
+
+      for (let i = 0; i < 3; i++) {
+        view.value = SlowComp
+        await nextTick()
+        view.value = FillerComp
+        await nextTick()
+      }
+
+      expect(resolvers.length).toBe(3)
+      resolvers.forEach(r => r(undefined))
+      await new Promise(r => setTimeout(r))
+
+      stateRef.value++
+      await nextTick()
+      expect(updateSpy).not.toHaveBeenCalled()
+    })
+
+    test('nested scope created after pending branch is abandoned', async () => {
+      const updateSpy = vi.fn()
+      const stateRef = ref(0)
+      let resolvePending!: (v?: unknown) => void
+
+      const SlowComp = defineComponent({
+        async setup() {
+          let __temp: any, __restore: any
+          ;[__temp, __restore] = withAsyncContext(
+            () =>
+              new Promise(r => {
+                resolvePending = r
+              }),
+          )
+          __temp = await __temp
+          __restore()
+
+          effectScope().run(() => {
+            watch(stateRef, updateSpy)
+          })
+
+          return () => h('div', 'slow')
+        },
+      })
+
+      const FillerComp = defineComponent({
+        setup: () => () => h('div', 'filler'),
+      })
+
+      const view = shallowRef<any>(SlowComp)
+      const Comp = defineComponent({
+        setup: () => () =>
+          h(Suspense, null, {
+            default: h(view.value),
+            fallback: h('div', 'fallback'),
+          }),
+      })
+
+      const root = nodeOps.createElement('div')
+      render(h(Comp), root)
+      expect(serializeInner(root)).toBe(`<div>fallback</div>`)
+
+      view.value = FillerComp
+      await nextTick()
+      expect(serializeInner(root)).toBe(`<div>filler</div>`)
+
+      resolvePending(undefined)
+      await new Promise(r => setTimeout(r))
+
+      stateRef.value++
+      await nextTick()
+      expect(updateSpy).not.toHaveBeenCalled()
+    })
+  })
 })