fix(coding-agent): disable undici http2

Fixes #4681. Fixes #4682.

packages/coding-agent/CHANGELOG.md

@@ -2,6 +2,10 @@
 
 ## [Unreleased]
 
+### Fixed
+
+- Fixed undici 8 HTTP/2 destroyed-session races crashing the Node CLI by preserving the previous HTTP/1.1-only fetch dispatcher behavior ([#4681](https://github.com/earendil-works/pi/issues/4681)).
+
 ## [0.75.2] - 2026-05-18
 
 ### Fixed

packages/coding-agent/src/cli.ts

@@ -17,7 +17,7 @@ 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.
-undici.setGlobalDispatcher(new undici.EnvHttpProxyAgent({ bodyTimeout: 0, headersTimeout: 0 }));
+undici.setGlobalDispatcher(new undici.EnvHttpProxyAgent({ allowH2: false, bodyTimeout: 0, headersTimeout: 0 }));
 
 // Keep fetch and the dispatcher on the same undici implementation. Node 26.0's
 // bundled fetch can otherwise consume compressed responses through npm undici's