From caae3601ee6441bfa6f3c0b45664cb0793974ab5 Mon Sep 17 00:00:00 2001
From: can1357 <me@can.ac>
Date: Thu, 13 Aug 2026 02:09:16 +0200
Subject: [PATCH] Revert "test(coding-agent): stabilize MCP stream resumption"

This reverts commit dc283c0deb08bb4063950f9d4b3e67f00a117760.
---
 .../test/mcp-http-transport.test.ts           | 65 +++++++++----------
 1 file changed, 32 insertions(+), 33 deletions(-)

diff --git a/packages/coding-agent/test/mcp-http-transport.test.ts b/packages/coding-agent/test/mcp-http-transport.test.ts
index e7244dc78..ce7c2a940 100644
--- a/packages/coding-agent/test/mcp-http-transport.test.ts
+++ b/packages/coding-agent/test/mcp-http-transport.test.ts
@@ -1,4 +1,4 @@
-import { afterEach, describe, expect, it, vi } from "bun:test";
+import { afterEach, describe, expect, it } from "bun:test";
 import { HttpTransport } from "@oh-my-pi/pi-coding-agent/mcp/transports/http";
 
 const encoder = new TextEncoder();
@@ -258,41 +258,41 @@ describe("MCP Streamable HTTP POST response resumption", () => {
 	});
 
 	it("resumes after an abrupt stream drop once an event ID exists", async () => {
-		const observed = { posts: 0, gets: 0, lastEventId: null as string | null };
-		const fetchMock: typeof globalThis.fetch = Object.assign(
-			async (_input: string | URL | Request, init?: RequestInit | BunFetchRequestInit): Promise<Response> => {
-				if (init?.method === "POST") {
-					observed.posts++;
-					let deliveredEvent = false;
-					return new Response(
-						new ReadableStream<Uint8Array>({
-							pull(controller) {
-								if (!deliveredEvent) {
-									deliveredEvent = true;
-									controller.enqueue(encoder.encode("id: stream-1\nretry: 10\ndata:\n\n"));
-									return;
-								}
-								controller.error(new Error("simulated abrupt stream drop"));
-							},
-						}),
-						{ headers: { "Content-Type": "text/event-stream" } },
+		// Bun.serve cannot produce a genuine mid-body transport failure in-process
+		// (stream errors surface as clean EOF client-side), so speak raw HTTP: a
+		// chunked response without the terminal chunk, closed mid-body, makes the
+		// client's body read throw.
+		const observed = { posts: 0, lastEventId: null as string | null };
+		const sseChunk = (payload: string): string =>
+			`HTTP/1.1 200 OK\r\nContent-Type: text/event-stream\r\nTransfer-Encoding: chunked\r\n\r\n${payload.length.toString(16)}\r\n${payload}\r\n`;
+		const listener = Bun.listen({
+			hostname: "127.0.0.1",
+			port: 0,
+			socket: {
+				data(socket, data) {
+					const request = new TextDecoder().decode(data);
+					if (request.startsWith("POST")) {
+						observed.posts++;
+						// Priming event, then close without the terminal 0-chunk.
+						socket.write(sseChunk("id: stream-1\nretry: 10\ndata:\n\n"));
+						socket.end();
+						return;
+					}
+					if (!request.startsWith("GET")) return;
+					observed.lastEventId = /^Last-Event-ID:\s*(.+)$/im.exec(request)?.[1]?.trim() ?? null;
+					socket.write(
+						`${sseChunk(
+							'id: stream-2\ndata: {"jsonrpc":"2.0","id":1,"result":{"tools":[{"name":"resumed","inputSchema":{"type":"object"}}]}}\n\n',
+						)}0\r\n\r\n`,
 					);
-				}
-				if (init?.method !== "GET") throw new Error(`Unexpected method: ${init?.method}`);
-				observed.gets++;
-				observed.lastEventId = new Headers(init.headers).get("Last-Event-ID");
-				return new Response(
-					'id: stream-2\ndata: {"jsonrpc":"2.0","id":1,"result":{"tools":[{"name":"resumed","inputSchema":{"type":"object"}}]}}\n\n',
-					{ headers: { "Content-Type": "text/event-stream" } },
-				);
+					socket.end();
+				},
 			},
-			{ preconnect: globalThis.fetch.preconnect },
-		);
-		const fetchSpy = vi.spyOn(globalThis, "fetch").mockImplementation(fetchMock);
+		});
 		try {
 			const transport = new HttpTransport({
 				type: "http",
-				url: "http://mcp.test/mcp",
+				url: `http://127.0.0.1:${listener.port}/mcp`,
 				timeout: GUARD_TIMEOUT_MS,
 			});
 			await transport.connect();
@@ -301,10 +301,9 @@ describe("MCP Streamable HTTP POST response resumption", () => {
 				tools: [{ name: "resumed", inputSchema: { type: "object" } }],
 			});
 			expect(observed.posts).toBe(1);
-			expect(observed.gets).toBe(1);
 			expect(observed.lastEventId).toBe("stream-1");
 		} finally {
-			fetchSpy.mockRestore();
+			listener.stop(true);
 		}
 	});
 });