From 8757e5b44bd670f6ded7ecaeb1e3458f31f53242 Mon Sep 17 00:00:00 2001
From: Devin AI <158243242+devin-ai-integration[bot]@users.noreply.github.com>
Date: Thu, 24 Sep 2026 08:15:23 +0000
Subject: [PATCH] Track effect subscriptions and restore tracking context in
 reactive core

Co-Authored-By: Shotaro Nakamura <syoutarou1103@outlook.jp>
---
 packages/eclipsa/core/reactive/core.test.ts | 50 +++++++++++++++++++++
 packages/eclipsa/core/reactive/core.ts      | 30 +++++++++----
 2 files changed, 71 insertions(+), 9 deletions(-)

diff --git a/packages/eclipsa/core/reactive/core.test.ts b/packages/eclipsa/core/reactive/core.test.ts
index 4726665..7c9cce1 100644
--- a/packages/eclipsa/core/reactive/core.test.ts
+++ b/packages/eclipsa/core/reactive/core.test.ts
@@ -53,4 +53,54 @@ describe('signal', () => {
     expect(cb).toHaveBeenNthCalledWith(2, '1:new')
     expect(cb).toHaveBeenNthCalledWith(3, '2:new')
   })
+
+  it('records read signals on the effect and unsubscribes them on dispose', () => {
+    const count = signal(0)
+    const cb = vi.fn()
+
+    const dispose = effect(() => {
+      cb(count.get())
+    })
+
+    expect(count.effects.size).toBe(1)
+    const [tracked] = count.effects
+    expect(tracked?.signals.has(count)).toBe(true)
+
+    dispose()
+
+    expect(count.effects.size).toBe(0)
+    count.set(1)
+    expect(cb).toHaveBeenCalledTimes(1)
+  })
+
+  it('restores the previous tracking context when an effect body throws', () => {
+    const count = signal(0)
+
+    expect(() =>
+      effect(() => {
+        throw new Error('boom')
+      }),
+    ).toThrow('boom')
+
+    count.get()
+    expect(count.effects.size).toBe(0)
+  })
+
+  it('keeps tracking the outer effect after a nested effect finishes', () => {
+    const outer = signal(0)
+    const inner = signal(0)
+    const outerCb = vi.fn()
+
+    effect(() => {
+      effect(() => {
+        inner.get()
+      })
+      outerCb(outer.get())
+    })
+
+    expect(outerCb).toHaveBeenCalledTimes(1)
+    outer.set(1)
+    expect(outerCb).toHaveBeenCalledTimes(2)
+    expect(outerCb).toHaveBeenNthCalledWith(2, 1)
+  })
 })
diff --git a/packages/eclipsa/core/reactive/core.ts b/packages/eclipsa/core/reactive/core.ts
index 0fbbf36..5195ebb 100644
--- a/packages/eclipsa/core/reactive/core.ts
+++ b/packages/eclipsa/core/reactive/core.ts
@@ -27,6 +27,7 @@ export const signal = <T>(init: T): Signal<T> => {
     get() {
       if (currentEffect) {
         this.effects.add(currentEffect)
+        currentEffect.signals.add(this)
       }
       return value
     },
@@ -45,23 +46,34 @@ export const signal = <T>(init: T): Signal<T> => {
   return signal
 }
 
-const registry = new FinalizationRegistry<Effect>((effect) => {
+const unsubscribeEffect = (effect: Effect) => {
   for (const signal of effect.signals) {
     signal.effects.delete(effect)
   }
-})
+  effect.signals.clear()
+}
+
+const registry = new FinalizationRegistry<Effect>(unsubscribeEffect)
 
-export const effect = (fn: () => void) => {
+export const effect = (fn: () => void): (() => void) => {
   const newEffect: Effect = {
-    fn() {
-      fn()
-    },
+    fn,
     signals: new Set(),
   }
 
+  const previousEffect = currentEffect
   currentEffect = newEffect
-  newEffect.fn()
-  currentEffect = null
+  try {
+    newEffect.fn()
+  } finally {
+    currentEffect = previousEffect
+  }
+
+  const dispose = () => {
+    registry.unregister(dispose)
+    unsubscribeEffect(newEffect)
+  }
+  registry.register(dispose, newEffect, dispose)
 
-  registry.register(fn, newEffect)
+  return dispose
 }