openclaw - 💡(How to fix) Fix openai-node streaming: event-only SSE flush causes JSON.parse('') crash (Unexpected end of JSON input) [1 participants]

Summary

When consuming an SSE stream, if an SSE “message” is flushed with an event: field but no data: lines (i.e. event: … followed by a blank line), the OpenAI Node SDK attempts JSON.parse on an empty string and throws:

• Unexpected end of JSON input

This shows up downstream in OpenClaw as intermittent job failures (e.g. startup-sync-guard, operator-digest, acp-*) when an OpenAI-compatible proxy/gateway incorrectly splits event: and data: across SSE message boundaries.

Environment

• OpenClaw: 2026.3.13 (61d171a)
• OpenAI Node SDK: 6.26.0 (vendored in OpenClaw install)
• Node.js: v25.8.1
• Platform: Linux x86_64

Minimal reproduction (no API keys; pure in-memory Response)

Save as repro.mjs:

import { Stream } from "openai/streaming";

const encoder = new TextEncoder();

// Simulate a proxy/gateway producing an event-only SSE message.
// Note: This is two SSE messages:
// 1) "event: message" with NO data (blank line flush)
// 2) a data-only message that would be parseable if we didn’t crash on (1)
const sseWire = [
  "event: message\n",
  "\n",
  "data: {\"ok\": true}\n",
  "\n",
].join("");

const body = new ReadableStream({
  start(controller) {
    controller.enqueue(encoder.encode(sseWire));
    controller.close();
  },
});

const response = new Response(body, {
  headers: { "content-type": "text/event-stream" },
});

const abort = new AbortController();

for await (const item of Stream.fromSSEResponse(response, abort)) {
  console.log("item:", item);
}

Run:

node repro.mjs

Expected behavior

• The SDK should ignore SSE messages with empty/whitespace-only data (or at least not attempt JSON.parse on ""), and continue consuming subsequent valid SSE messages.

Actual behavior

• The SDK throws Unexpected end of JSON input because it executes JSON.parse(sse.data) when sse.data === "".

Root cause

In openai/core/streaming.*:

• SSEDecoder.decode() flushes an SSE object on a blank line whenever either event is set or any data lines exist.
• Stream.fromSSEResponse() then unconditionally does JSON.parse(sse.data).

So an event: line followed by a blank line produces an event-only message with data: "", which crashes JSON parsing.

Temporary local hotfix that unblocked OpenClaw jobs

In class SSEDecoder { decode(line) { ... } }, inside the if (!line) { ... } branch:

// Treat event-only chunks as incomplete and wait for `data:`.
if (this.event && !this.data.length) {
  return null;
}

Suggested official fix direction

One of:

1. Preferred (minimal): In Stream.fromSSEResponse, skip JSON.parse for empty/whitespace sse.data (treat as keepalive / malformed event).
2. Alternative: In SSEDecoder.decode(), do not flush a message when there are no data: lines.

Suggested tests

Add unit tests that build an in-memory Response (like the repro) and assert:

1. No throw on event: message\n\n (event-only flush); yields no items.
2. Event-only flush followed by a valid data: message: no throw; yields the later parsed object.
3. CRLF delimiter variants (\r\n\r\n).