fix(coding-agent): tunnel proxied HTTP requests

closes #8134

packages/coding-agent/CHANGELOG.md

@@ -2,6 +2,10 @@
 
 ## [Unreleased]
 
+### Fixed
+
+- Fixed proxied plain-HTTP provider requests hanging after a tool call by tunneling them with CONNECT ([#8134](https://github.com/earendil-works/pi/issues/8134)).
+
 ## [0.84.4] - 2026-08-28
 
 ### New Features

packages/coding-agent/src/core/http-dispatcher.ts

@@ -86,6 +86,8 @@ export function configureHttpDispatcher(timeoutMs: number = DEFAULT_HTTP_IDLE_TI
 	const dispatcher = withUndiciErrorListener(
 		new undici.EnvHttpProxyAgent({
 			allowH2: false,
+			// Keep HTTP origins on CONNECT tunnels as they were before Undici 8.7.
+			proxyTunnel: true,
 			bodyTimeout: normalizedTimeoutMs,
 			connect: {
 				autoSelectFamilyAttemptTimeout: DEFAULT_AUTO_SELECT_FAMILY_ATTEMPT_TIMEOUT_MS,

packages/coding-agent/test/http-dispatcher.test.ts

@@ -1,3 +1,4 @@
+import http from "node:http";
 import net from "node:net";
 import tls from "node:tls";
 import * as undici from "undici";
@@ -5,7 +6,7 @@ import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
 import { applyHttpProxySettings, configureHttpDispatcher } from "../src/core/http-dispatcher.ts";
 
 const PROXY_ENV_KEYS = ["HTTP_PROXY", "HTTPS_PROXY"] as const;
-const DISPATCHER_PROXY_ENV_KEYS = [...PROXY_ENV_KEYS, "http_proxy", "https_proxy"] as const;
+const DISPATCHER_PROXY_ENV_KEYS = [...PROXY_ENV_KEYS, "http_proxy", "https_proxy", "NO_PROXY", "no_proxy"] as const;
 
 describe("http proxy settings", () => {
 	let savedEnv: Record<(typeof PROXY_ENV_KEYS)[number], string | undefined>;
@@ -89,6 +90,63 @@ describe("http dispatcher", () => {
 		vi.restoreAllMocks();
 	});
 
+	it("tunnels proxied HTTP origins", async () => {
+		const origin = http.createServer((_request, response) => {
+			response.end("origin");
+		});
+		await new Promise<void>((resolve) => origin.listen(0, "127.0.0.1", resolve));
+		const originAddress = origin.address();
+		if (!originAddress || typeof originAddress === "string") {
+			throw new Error("Origin did not bind to a TCP port");
+		}
+
+		const proxyRequestLines: string[] = [];
+		const proxy = net.createServer((client) => {
+			client.once("data", (data) => {
+				const [requestLine = ""] = data.toString().split("\r\n");
+				proxyRequestLines.push(requestLine);
+				if (!requestLine.startsWith("CONNECT ")) {
+					client.end("HTTP/1.1 501 Not Implemented\r\ncontent-length: 0\r\nconnection: close\r\n\r\n");
+					return;
+				}
+
+				const upstream = net.connect(originAddress.port, "127.0.0.1", () => {
+					client.write("HTTP/1.1 200 Connection Established\r\n\r\n");
+					client.pipe(upstream).pipe(client);
+				});
+				upstream.on("error", () => client.destroy());
+				client.on("error", () => upstream.destroy());
+			});
+		});
+		await new Promise<void>((resolve) => proxy.listen(0, "127.0.0.1", resolve));
+		const proxyAddress = proxy.address();
+		if (!proxyAddress || typeof proxyAddress === "string") {
+			throw new Error("Proxy did not bind to a TCP port");
+		}
+
+		process.env.HTTP_PROXY = `http://127.0.0.1:${proxyAddress.port}`;
+		configureHttpDispatcher();
+		const dispatcher = undici.getGlobalDispatcher();
+		try {
+			const originUrl = `http://127.0.0.1:${originAddress.port}/v1/chat/completions`;
+			await expect(undici.fetch(originUrl).then((response) => response.text())).resolves.toBe("origin");
+			await expect(undici.fetch(originUrl).then((response) => response.text())).resolves.toBe("origin");
+			expect(proxyRequestLines).not.toHaveLength(0);
+			expect(proxyRequestLines).toEqual(
+				expect.arrayContaining([
+					expect.stringMatching(`^CONNECT 127\\.0\\.0\\.1:${originAddress.port} HTTP/1\\.1$`),
+				]),
+			);
+		} finally {
+			await dispatcher.close();
+			undici.setGlobalDispatcher(originalDispatcher);
+			await Promise.all([
+				new Promise<void>((resolve) => proxy.close(() => resolve())),
+				new Promise<void>((resolve) => origin.close(() => resolve())),
+			]);
+		}
+	});
+
 	it("allows two seconds for HTTPS connection attempts without changing the Node default", async () => {
 		// Preserve a deliberate host fetch override while testing the dispatcher itself.
 		globalThis.fetch = async () => {