fix(mcp): report the bound HTTP port

.changeset/report-bound-http-port.md

@@ -0,0 +1,5 @@
+---
+"@upstash/context7-mcp": patch
+---
+
+Report the actual assigned HTTP port when `--port 0` requests an ephemeral port.

packages/mcp/src/index.ts

@@ -539,8 +539,13 @@ async function main() {
       });
 
       httpServer.once("listening", () => {
+        const address = httpServer.address();
+        if (!address || typeof address === "string") {
+          console.error("Failed to determine the bound HTTP port");
+          process.exit(1);
+        }
         console.error(
-          `Context7 Documentation MCP Server v${SERVER_VERSION} running on HTTP at http://localhost:${port}/mcp`
+          `Context7 Documentation MCP Server v${SERVER_VERSION} running on HTTP at http://localhost:${address.port}/mcp`
         );
       });
     };

packages/mcp/test/integration.test.ts

@@ -71,13 +71,12 @@ function startStubApi(): Promise<string> {
   });
 }
 
-function startHttpChild(): Promise<{ child: ChildProcess; url: string }> {
+function startHttpChild(port = BASE_PORT): Promise<{ child: ChildProcess; url: string }> {
   return new Promise((resolve, reject) => {
-    const child = spawn(
-      process.execPath,
-      [DIST, "--transport", "http", "--port", String(BASE_PORT)],
-      { env: childEnv, stdio: ["ignore", "ignore", "pipe"] }
-    );
+    const child = spawn(process.execPath, [DIST, "--transport", "http", "--port", String(port)], {
+      env: childEnv,
+      stdio: ["ignore", "ignore", "pipe"],
+    });
     let stderr = "";
     child.stderr!.on("data", (chunk: Buffer) => {
       stderr += chunk.toString();
@@ -105,6 +104,19 @@ afterAll(() => {
   stubServer?.close();
 });
 
+test("reports the bound port when port zero requests an ephemeral port", async () => {
+  const { child, url } = await startHttpChild(0);
+  try {
+    expect(new URL(url).port).not.toBe("0");
+
+    const response = await fetch(new URL("/ping", url));
+    expect(response.ok).toBe(true);
+    await expect(response.json()).resolves.toMatchObject({ status: "ok" });
+  } finally {
+    child.kill();
+  }
+});
+
 async function connect(transportKind: "http" | "stdio", era: "modern" | "legacy") {
   const client = new Client(
     { name: "test-harness", version: "1.0.0" },