From f76aa2a7519b40636c643a3eece004fd587a88a2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Fernando=20Fern=C3=A1ndez?= <ferferga@hotmail.com>
Date: Fri, 9 May 2025 07:30:33 +0000
Subject: [PATCH] refactor: don't run components in detached effectScopes

---
 packages/reactivity/src/effectScope.ts | 35 ++++++++++++++++++--------
 packages/runtime-core/src/component.ts |  2 +-
 2 files changed, 25 insertions(+), 12 deletions(-)

diff --git a/packages/reactivity/src/effectScope.ts b/packages/reactivity/src/effectScope.ts
index 2e741f92ffd..4eec95c29c4 100644
--- a/packages/reactivity/src/effectScope.ts
+++ b/packages/reactivity/src/effectScope.ts
@@ -45,16 +45,26 @@ export class EffectScope implements Subscriber {
    */
   private index: number | undefined
 
-  constructor(public detached = false) {
-    this.parent = activeEffectScope
-    if (!detached && activeEffectScope) {
+  /**
+   * @param relationship - Defines the parent scope of the current effect scope.
+   * - If `true`, the scope is detached from any parent.
+   * - If an instance of `EffectScope`, it becomes the parent scope.
+   * - Defaults to `false`, indicating the effect scope is attached to the parent if it exists.
+   */
+  constructor(relationship: EffectScope | boolean = false) {
+    this.parent =
+      relationship === true ? undefined : relationship || activeEffectScope
+
+    if (this.parent) {
       this.index =
-        (activeEffectScope.scopes || (activeEffectScope.scopes = [])).push(
-          this,
-        ) - 1
+        (this.parent.scopes || (this.parent.scopes = [])).push(this) - 1
     }
   }
 
+  get detached(): boolean {
+    return !this.parent
+  }
+
   get active(): boolean {
     return !(this.flags & EffectFlags.STOP)
   }
@@ -153,9 +163,9 @@ export class EffectScope implements Subscriber {
       }
 
       // nested scope, dereference from parent to avoid memory leaks
-      if (!this.detached && this.parent && !fromParent) {
+      if (!this.detached && this.parent && this.parent.scopes && !fromParent) {
         // optimized O(1) removal
-        const last = this.parent.scopes!.pop()
+        const last = this.parent.scopes.pop()
         if (last && last !== this) {
           this.parent.scopes![this.index!] = last
           last.index = this.index!
@@ -172,11 +182,14 @@ export class EffectScope implements Subscriber {
  * disposed together. For detailed use cases of this API, please consult its
  * corresponding {@link https://github.com/vuejs/rfcs/blob/master/active-rfcs/0041-reactivity-effect-scope.md | RFC}.
  *
- * @param detached - Can be used to create a "detached" effect scope.
+ * @param relationship - Defines the parent scope of the current effect scope.
+ * - If `true`, the scope is detached from any parent.
+ * - If an instance of `EffectScope`, it becomes the parent scope.
+ * - Defaults to `false`, indicating the effect scope is attached to the parent if it exists.
  * @see {@link https://vuejs.org/api/reactivity-advanced.html#effectscope}
  */
-export function effectScope(detached?: boolean): EffectScope {
-  return new EffectScope(detached)
+export function effectScope(relationship?: EffectScope | boolean): EffectScope {
+  return new EffectScope(relationship)
 }
 
 /**
diff --git a/packages/runtime-core/src/component.ts b/packages/runtime-core/src/component.ts
index 3ed42ed0b55..b776ee78784 100644
--- a/packages/runtime-core/src/component.ts
+++ b/packages/runtime-core/src/component.ts
@@ -623,7 +623,7 @@ export function createComponentInstance(
     effect: null!,
     update: null!, // will be set synchronously right after creation
     job: null!,
-    scope: new EffectScope(true /* detached */),
+    scope: parent ? new EffectScope(parent.scope) : new EffectScope(true),
     render: null,
     proxy: null,
     exposed: null,