From 35be66df5bdbcf8962a02575179472f3bc0a50d4 Mon Sep 17 00:00:00 2001
From: Dinh Le <dinwwwh@gmail.com>
Date: Tue, 29 Sep 2026 15:10:17 +0700
Subject: [PATCH] feat(fetch)!: always send close event, remove
 `emptyCloseEventEnabled` option

`toEventStream` now always emits a `close` event when the iterator
completes, including when it returns `undefined`, so clients can
reliably tell a finished stream from a dropped connection.
---
 packages/fetch/src/event-stream.test.ts | 81 -------------------------
 packages/fetch/src/event-stream.ts      | 22 ++-----
 2 files changed, 5 insertions(+), 98 deletions(-)

diff --git a/packages/fetch/src/event-stream.test.ts b/packages/fetch/src/event-stream.test.ts
index a1e57855..dab0e27e 100644
--- a/packages/fetch/src/event-stream.test.ts
+++ b/packages/fetch/src/event-stream.test.ts
@@ -583,87 +583,6 @@ describe('toEventStream', () => {
       await expect(reader.read()).resolves.toEqual({ done: true })
     })
   })
-
-  describe('empty close event', () => {
-    it('enabled by default', async () => {
-      async function* gen() {
-        yield 'hello'
-      }
-
-      const stream = toEventStream(gen(), {
-        initialComment: { enabled: false },
-        keepAlive: { enabled: false },
-      })
-
-      const reader = stream
-        .pipeThrough(new TextDecoderStream())
-        .getReader()
-
-      await expect(reader.read()).resolves.toEqual({ done: false, value: 'event: message\ndata: "hello"\n\n' })
-      await expect(reader.read()).resolves.toEqual({ done: false, value: 'event: close\n\n' })
-      await expect(reader.read()).resolves.toEqual({ done: true })
-    })
-
-    it('disabled', async () => {
-      async function* gen() {
-        yield 'hello'
-      }
-
-      const stream = toEventStream(gen(), {
-        initialComment: { enabled: false },
-        keepAlive: { enabled: false },
-        emptyCloseEventEnabled: false,
-      })
-
-      const reader = stream
-        .pipeThrough(new TextDecoderStream())
-        .getReader()
-
-      await expect(reader.read()).resolves.toEqual({ done: false, value: 'event: message\ndata: "hello"\n\n' })
-      await expect(reader.read()).resolves.toEqual({ done: true })
-    })
-
-    it('enabled explicitly', async () => {
-      async function* gen() {
-        yield 'hello'
-      }
-
-      const stream = toEventStream(gen(), {
-        initialComment: { enabled: false },
-        keepAlive: { enabled: false },
-        emptyCloseEventEnabled: true,
-      })
-
-      const reader = stream
-        .pipeThrough(new TextDecoderStream())
-        .getReader()
-
-      await expect(reader.read()).resolves.toEqual({ done: false, value: 'event: message\ndata: "hello"\n\n' })
-      await expect(reader.read()).resolves.toEqual({ done: false, value: 'event: close\n\n' })
-      await expect(reader.read()).resolves.toEqual({ done: true })
-    })
-
-    it.each([true, false])('still sends close event when iterator returns a value: %s', async (emptyCloseEventEnabled) => {
-      async function* gen() {
-        yield 'hello'
-        return 'bye'
-      }
-
-      const stream = toEventStream(gen(), {
-        initialComment: { enabled: false },
-        keepAlive: { enabled: false },
-        emptyCloseEventEnabled,
-      })
-
-      const reader = stream
-        .pipeThrough(new TextDecoderStream())
-        .getReader()
-
-      await expect(reader.read()).resolves.toEqual({ done: false, value: 'event: message\ndata: "hello"\n\n' })
-      await expect(reader.read()).resolves.toEqual({ done: false, value: 'event: close\ndata: "bye"\n\n' })
-      await expect(reader.read()).resolves.toEqual({ done: true })
-    })
-  })
 })
 
 it.each([
diff --git a/packages/fetch/src/event-stream.ts b/packages/fetch/src/event-stream.ts
index 0b34cc22..acbef216 100644
--- a/packages/fetch/src/event-stream.ts
+++ b/packages/fetch/src/event-stream.ts
@@ -113,14 +113,6 @@ export interface ToEventStreamOptions {
      */
     comment?: string
   }
-
-  /**
-   * If true, a `close` event is sent even when the iterator completes with `undefined`.
-   * When the iterator returns a value, a `close` event is always emitted regardless of this setting.
-   *
-   * @default true
-   */
-  emptyCloseEventEnabled?: boolean
 }
 
 export function toEventStream(
@@ -132,7 +124,6 @@ export function toEventStream(
   const keepAliveComment = options.keepAlive?.comment ?? ''
   const initialCommentEnabled = options.initialComment?.enabled ?? true
   const initialComment = options.initialComment?.comment ?? ''
-  const emptyCloseEventEnabled = options.emptyCloseEventEnabled ?? true
 
   let cancelled = false
   let timeout: ReturnType<typeof setInterval> | undefined
@@ -193,14 +184,11 @@ export function toEventStream(
       try {
         const [data, meta] = unwrapEvent(result.value)
 
-        if (!result.done || data !== undefined || meta !== undefined || emptyCloseEventEnabled) {
-          const event = result.done ? 'close' : 'message'
-          controller.enqueue(encodeEventStreamMessage({
-            ...meta,
-            event,
-            data: stringifyJSON(data),
-          }))
-        }
+        controller.enqueue(encodeEventStreamMessage({
+          ...meta,
+          event: result.done ? 'close' : 'message',
+          data: stringifyJSON(data),
+        }))
       }
       catch (err) {
         /**