fix(codex): harden streaming timeouts + Responses terminal events

Raise stall/connect timeouts to 60s (configurable per-provider), accept
codex response.done, and always emit a terminal response.failed + [DONE]
for Responses passthrough when a stream closes, stalls, or aborts before
a terminal event — preventing codex clients from hanging.

Co-authored-by: jonathanli12 <jonathanli12@users.noreply.github.com>
Co-authored-by: rifuki <rifuki@users.noreply.github.com>
Co-authored-by: nguyenha935 <nguyenha935@users.noreply.github.com>
Co-authored-by: trananhtung <trananhtung@users.noreply.github.com>
Co-authored-by: Cursor <cursoragent@cursor.com>

tests/unit/responses-abort-terminal.test.js

@@ -0,0 +1,72 @@
+import { describe, expect, it } from "vitest";
+
+import { createDisconnectAwareStream } from "../../open-sse/utils/streamHandler.js";
+import { buildAbortedResponsesTerminalBytes } from "../../open-sse/utils/responsesStreamHelpers.js";
+
+// Minimal stream controller stub
+function makeController() {
+  let connected = true;
+  return {
+    signal: new AbortController().signal,
+    startTime: Date.now(),
+    isConnected: () => connected,
+    handleComplete: () => { connected = false; },
+    handleError: () => { connected = false; },
+    handleDisconnect: () => { connected = false; },
+    abort: () => { connected = false; },
+  };
+}
+
+async function readAll(stream) {
+  const reader = stream.getReader();
+  const decoder = new TextDecoder();
+  let text = "";
+  while (true) {
+    const { value, done } = await reader.read();
+    if (done) break;
+    text += decoder.decode(value, { stream: true });
+  }
+  text += decoder.decode();
+  return text;
+}
+
+describe("Responses abort terminal synthesis", () => {
+  it("emits response.failed + [DONE] when upstream errors (abort/stall)", async () => {
+    // Upstream readable that errors mid-stream (simulates fetch abort on stall)
+    const upstream = new ReadableStream({
+      start(controller) {
+        controller.enqueue(new TextEncoder().encode("event: response.created\ndata: {}\n\n"));
+        controller.error(new Error("stream stall timeout"));
+      },
+    });
+
+    const out = createDisconnectAwareStream(
+      { readable: upstream, writable: { getWriter: () => ({ abort: () => Promise.resolve() }) } },
+      makeController(),
+      buildAbortedResponsesTerminalBytes
+    );
+
+    const text = await readAll(out);
+    expect(text).toContain("event: response.failed");
+    expect(text).toContain("data: [DONE]");
+  });
+
+  it("does not synthesize terminal for non-Responses streams (callback null)", async () => {
+    const upstream = new ReadableStream({
+      start(controller) {
+        controller.enqueue(new TextEncoder().encode("data: hi\n\n"));
+        controller.error(new Error("socket hang up"));
+      },
+    });
+
+    const out = createDisconnectAwareStream(
+      { readable: upstream, writable: { getWriter: () => ({ abort: () => Promise.resolve() }) } },
+      makeController(),
+      null
+    );
+
+    const text = await readAll(out);
+    expect(text).not.toContain("response.failed");
+    expect(text).not.toContain("[DONE]");
+  });
+});