fix(coding-agent): route global fetch through undici dispatcher closes #4519

packages/coding-agent/CHANGELOG.md

@@ -9,6 +9,7 @@
 
 ### Fixed
 
+- Fixed Node 26 OpenAI-compatible streams timing out after five idle minutes by routing global fetch through pi's undici dispatcher ([#4519](https://github.com/earendil-works/pi/issues/4519)).
 - Fixed macOS clipboard access errors under sandboxed pasteboard denial so they do not abort the process ([#4492](https://github.com/earendil-works/pi/issues/4492)).
 - Fixed the scoped model startup hint to show the configured model-cycle keybinding ([#4508](https://github.com/earendil-works/pi/issues/4508)).
 - Fixed `fd` auto-download on macOS x86_64 by pinning the last release that ships an Intel macOS binary ([#4559](https://github.com/earendil-works/pi/issues/4559)).

packages/coding-agent/src/cli.ts

@@ -5,7 +5,7 @@
  *
  * Test with: npx tsx src/cli-new.ts [args...]
  */
-import { EnvHttpProxyAgent, setGlobalDispatcher } from "undici";
+import { EnvHttpProxyAgent, setGlobalDispatcher, fetch as undiciFetch } from "undici";
 import { APP_NAME } from "./config.js";
 import { main } from "./main.js";
 
@@ -17,6 +17,15 @@ process.emitWarning = (() => {}) as typeof process.emitWarning;
 // (e.g. vLLM buffering a large tool call) exceed that and abort the SSE stream
 // with UND_ERR_BODY_TIMEOUT. Disable both — provider SDKs enforce their own
 // AbortController-based deadlines via retry.provider.timeoutMs.
-setGlobalDispatcher(new EnvHttpProxyAgent({ bodyTimeout: 0, headersTimeout: 0 }));
+// Node 26 uses an internal undici for globalThis.fetch that does not honor npm
+// undici's global dispatcher, so route global fetch through npm undici as well.
+const dispatcher = new EnvHttpProxyAgent({ bodyTimeout: 0, headersTimeout: 0 });
+setGlobalDispatcher(dispatcher);
+const fetchWithDispatcher = undiciFetch as unknown as typeof fetch;
+globalThis.fetch = (input, init) =>
+	fetchWithDispatcher(input, {
+		...init,
+		dispatcher,
+	} as unknown as RequestInit);
 
 main(process.argv.slice(2));