fix(gateway): preserve unbracketed IPv6 host headers

src/gateway/net.test.ts

@@ -5,8 +5,21 @@ import {
   isTrustedProxyAddress,
   pickPrimaryLanIPv4,
   resolveGatewayListenHosts,
+  resolveHostName,
 } from "./net.js";
 
+describe("resolveHostName", () => {
+  it("returns hostname without port for IPv4/hostnames", () => {
+    expect(resolveHostName("localhost:18789")).toBe("localhost");
+    expect(resolveHostName("127.0.0.1:18789")).toBe("127.0.0.1");
+  });
+
+  it("handles bracketed and unbracketed IPv6 loopback hosts", () => {
+    expect(resolveHostName("[::1]:18789")).toBe("::1");
+    expect(resolveHostName("::1")).toBe("::1");
+  });
+});
+
 describe("isTrustedProxyAddress", () => {
   describe("exact IP matching", () => {
     it("returns true when IP matches exactly", () => {

src/gateway/net.ts

@@ -40,6 +40,10 @@ export function resolveHostName(hostHeader?: string): string {
       return host.slice(1, end);
     }
   }
+  // Unbracketed IPv6 host (e.g. "::1") has no port and should be returned as-is.
+  if (net.isIP(host) === 6) {
+    return host;
+  }
   const [name] = host.split(":");
   return name ?? "";
 }