From 8fd93a11bccd52ef5d753a3360e77dc070ae7e32 Mon Sep 17 00:00:00 2001
From: Yuxin Qiao <104957188+Yuxin-Qiao@users.noreply.github.com>
Date: Sat, 8 Aug 2026 11:13:58 +0800
Subject: [PATCH] fix(openai-chat): ignore empty data: frames; tighten unspaced
 [DONE] test

Follow-up to #1194 carrying forward the two pieces of #1188 that the
superseding PR did not take, per maintainer review:

- A bare `data:` line (heartbeat-style keep-alive on some gateways) now
  yields no payload and is skipped, instead of falling into JSON.parse("")
  and terminating the stream as a malformed frame.
- The unspaced [DONE] regression test is driven by the sentinel frame
  alone: with a preceding answer frame, the finish-less EOF fallback
  could emit done even if unspaced [DONE] parsing were broken.
---
 src/adapters/openai-chat.ts            |  3 +++
 tests/sse-unspaced-data-fields.test.ts | 15 +++++++++++++--
 2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/src/adapters/openai-chat.ts b/src/adapters/openai-chat.ts
index 42a923657..09c94b069 100644
--- a/src/adapters/openai-chat.ts
+++ b/src/adapters/openai-chat.ts
@@ -951,6 +951,9 @@ export function createOpenAIChatAdapter(provider: OcxProviderConfig): ProviderAd
         const rawPayload = sseFieldValue(line, "data");
         if (rawPayload === null) return "continue";
         const payload = rawPayload.trim();
+        // A bare `data:` line carries nothing (heartbeat-style keep-alive on some gateways);
+        // it is not a malformed frame, just nothing to parse.
+        if (payload.length === 0) return "continue";
         if (payload === "[DONE]") {
           yield* flushToolCalls();
           const stopReason = stopReasonFor(finishReason);
diff --git a/tests/sse-unspaced-data-fields.test.ts b/tests/sse-unspaced-data-fields.test.ts
index 3df1db33f..a1b6322c9 100644
--- a/tests/sse-unspaced-data-fields.test.ts
+++ b/tests/sse-unspaced-data-fields.test.ts
@@ -112,12 +112,23 @@ describe("openai-chat adapter (#1170)", () => {
   });
 
   test("accepts an unspaced [DONE] sentinel", async () => {
+    // Sentinel only: a preceding answer frame would let the finish-less EOF fallback emit
+    // `done` even if unspaced [DONE] handling were broken, so this test must not carry one.
+    const response = new Response("data:[DONE]\n\n");
+    const events = await collect(createOpenAIChatAdapter(provider).parseStream(response));
+    expect(events.at(-1)?.type).toBe("done");
+    expect(events.some(e => e.type === "error")).toBe(false);
+  });
+
+  test("a bare data: line is ignored, not reported as a malformed frame", async () => {
     const response = new Response([
-      'data:{"choices":[{"delta":{"content":"hi"}}]}\n\n',
-      "data:[DONE]\n\n",
+      "data:\n\n",
+      'data:{"choices":[{"delta":{"content":"hi"},"finish_reason":"stop"}]}\n\n',
     ].join(""));
     const events = await collect(createOpenAIChatAdapter(provider).parseStream(response));
+    expect(events.find(e => e.type === "text_delta")).toMatchObject({ type: "text_delta", text: "hi" });
     expect(events.at(-1)?.type).toBe("done");
+    expect(events.some(e => e.type === "error")).toBe(false);
   });
 
   test("still handles the spaced form identically", async () => {