feedback7 G-TOOLS: listen on :: by default so one socket serves IPv6 and IPv4 (PR #291 by @LimitlessHPPK)

Ported only the dual-stack listen from PR #291 (the change accepted as #188). With HOST unset the server binds :: and, if that fails with EAFNOSUPPORT, EADDRNOTAVAIL or EINVAL, retries 0.0.0.0. An explicit HOST, including 0.0.0.0 and 127.0.0.1, is tried once. The boot banner and doctor list shareable IPv6 addresses in brackets, skip fe80::, and keep one URL per /64. An explicit IPv6 literal in the local URL is bracketed. The Windows service listing no longer drops those bracketed lines.

Not ported: /dev/grant, the settings-default migration, and the firewall scripts. The Docker image stays on 0.0.0.0; the alpine fallback was not booted.

Tests: node --test test/ipv6-bind.test.js test/doctor.test.js test/ci.test.js — 20 pass, 0 fail (8 bind, 4 doctor, 8 ci).

server/index.js

@@ -1,7 +1,7 @@
 // server/index.js — process entry & boot (DESIGN §1, §2). Plain node:http + ws, no framework: startServer() below
 // wires the modules under server/http/, in this order —
 //
-//   http/config.js     ROOT, the served directories, the environment (PORT 3000, HOST 0.0.0.0, TRUST_PROXY auto, DEBUG),
+//   http/config.js     ROOT, the served directories, the environment (PORT 3000, HOST '::' dual-stack, TRUST_PROXY auto, DEBUG),
 //                      which startServer() options go to net.js / lobby.js, the console logger
 //   http/websocket.js  session wiring (SessionRegistry → Lobby → Network) and the WebSocket at /ws (maxPayload 64 KB;
 //                      refused at upgrade with 404 / 429 per network / 503)
@@ -24,7 +24,7 @@
 
 import http from 'node:http';
 import { getData, loadData } from './data.js';
-import { ROOT, listenAddress, serveDirs, makeLogger, parseTrustProxy } from './http/config.js';
+import { ROOT, listenAddress, bindCandidates, serveDirs, makeLogger, parseTrustProxy } from './http/config.js';
 import { WS_MAX_PAYLOAD, createSessionStack, attachWebSocket } from './http/websocket.js';
 import { DATA_SHIM_JS, createStaticHandler } from './http/static.js';
 import { createPackRegistry } from './packs.js';
@@ -32,7 +32,7 @@ import { MIME, COMPRESSIBLE, acceptsGzip, parseRange } from './http/files.js';
 import { BUILD_INPUTS, computeBuildTag, buildTag, resetBuildTag } from './http/buildTag.js';
 import { createRequestHandler } from './http/routes.js';
 import { answerClientError } from './http/common.js';
-import { lanUrls, isProcessEntry, runMain } from './http/boot.js';
+import { lanUrls, displayHost, isProcessEntry, runMain } from './http/boot.js';
 
 // The public API of this module (tests and tools import it from here); the code lives in ./http/.
 export {
@@ -77,14 +77,35 @@ export async function startServer(opts = {}) {
   server.on('clientError', answerClientError);
   const wss = attachWebSocket(server, { network, log });
 
+  // The address actually bound. The default may fall back to IPv4; the returned host and url follow that.
+  let boundHost;
   try {
-    await new Promise((resolve, reject) => {
-      const onError = (e) => { server.off('listening', onListening); reject(e); };
-      const onListening = () => { server.off('error', onError); resolve(); };
-      server.once('error', onError);
-      server.once('listening', onListening);
-      server.listen(port, host);
-    });
+    // A host with IPv6 switched off refuses '::'. Fall back to IPv4 rather than not booting. Only the default is
+    // retried: an explicit HOST is literal (server/http/config.js bindCandidates).
+    let bound = null;
+    let lastError = null;
+    const candidates = bindCandidates(host);
+    for (let i = 0; i < candidates.length; i++) {
+      const candidate = candidates[i];
+      try {
+        await new Promise((resolve, reject) => {
+          const onError = (e) => { server.off('listening', onListening); reject(e); };
+          const onListening = () => { server.off('error', onError); resolve(); };
+          server.once('error', onError);
+          server.once('listening', onListening);
+          server.listen(port, candidate);
+        });
+        bound = candidate;
+        break;
+      } catch (e) {
+        lastError = e;
+        const retry = ['EAFNOSUPPORT', 'EADDRNOTAVAIL', 'EINVAL'].includes(e.code) && i < candidates.length - 1;
+        if (!retry) break;
+        log.warn(`[boot] cannot bind ${candidate} (${e.code}) — falling back to IPv4 only`);
+      }
+    }
+    if (bound === null) throw lastError;
+    boundHost = bound;
   } catch (e) {
     network.close(); // stop heartbeat/sweep timers of the half-built server
     throw e;
@@ -93,7 +114,7 @@ export async function startServer(opts = {}) {
 
   const addr = server.address();
   const actualPort = typeof addr === 'object' && addr ? addr.port : port;
-  const url = `http://${host === '0.0.0.0' || host === '::' ? 'localhost' : host}:${actualPort}`;
+  const url = `http://${displayHost(boundHost)}:${actualPort}`;
 
   let closing = null;
   async function close() {
@@ -111,7 +132,7 @@ export async function startServer(opts = {}) {
     return closing;
   }
 
-  return { port: actualPort, host, url, server, wss, lobby, network, registry, packs, close };
+  return { port: actualPort, host: boundHost, url, server, wss, lobby, network, registry, packs, close };
 }
 
 // `node server/index.js` / npm start: listen, print the banner, stop on SIGINT / SIGTERM (http/boot.js).