From b42a5cf59a03459a698bd5fe4e92616d935187f7 Mon Sep 17 00:00:00 2001
From: Sarp Tan Doven <119648987+sarptandoven@users.noreply.github.com>
Date: Mon, 6 Jul 2026 14:22:09 -0700
Subject: [PATCH] fix: set event-stream accept header

Use text/event-stream as the default Accept header when request options enable streaming while preserving explicit Accept overrides. Add regression coverage for streaming, non-streaming, and override cases.
---
 src/client.ts       |  2 +-
 tests/index.test.ts | 20 ++++++++++++++++++++
 2 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/src/client.ts b/src/client.ts
index c7df965cd..ed713683b 100644
--- a/src/client.ts
+++ b/src/client.ts
@@ -1157,7 +1157,7 @@ export class OpenAI {
     const headers = buildHeaders([
       idempotencyHeaders,
       {
-        Accept: 'application/json',
+        Accept: options.stream ? 'text/event-stream' : 'application/json',
         'User-Agent': this.getUserAgent(),
         'X-Stainless-Retry-Count': String(retryCount),
         ...(options.timeout ? { 'X-Stainless-Timeout': String(Math.trunc(options.timeout / 1000)) } : {}),
diff --git a/tests/index.test.ts b/tests/index.test.ts
index e19e33b98..a83a59269 100644
--- a/tests/index.test.ts
+++ b/tests/index.test.ts
@@ -27,6 +27,26 @@ describe('instantiate client', () => {
       adminAPIKey: 'My Admin API Key',
     });
 
+    test('uses an event-stream accept header for streaming requests', async () => {
+      const { req } = await client.buildRequest({ path: '/foo', method: 'post', stream: true });
+      expect(req.headers.get('accept')).toEqual('text/event-stream');
+    });
+
+    test('uses a JSON accept header for non-streaming requests', async () => {
+      const { req } = await client.buildRequest({ path: '/foo', method: 'post', stream: false });
+      expect(req.headers.get('accept')).toEqual('application/json');
+    });
+
+    test('preserves an explicit accept header for streaming requests', async () => {
+      const { req } = await client.buildRequest({
+        path: '/foo',
+        method: 'post',
+        stream: true,
+        headers: { Accept: 'application/x-ndjson' },
+      });
+      expect(req.headers.get('accept')).toEqual('application/x-ndjson');
+    });
+
     test('they are used in the request', async () => {
       const { req } = await client.buildRequest({ path: '/foo', method: 'post' });
       expect(req.headers.get('x-my-default-header')).toEqual('2');