feat(docker): support codex oauth login in networked harness

codex login binds its callback server to container loopback, so the host
browser redirect to localhost:1455 is refused. Publish 127.0.0.1:1455 on
the opt-in networked service only and bridge it to loopback with a small
node relay. Document the flow, fresh-state retry, and token lifetime in
the hardened-harness skill.

Follow-up to #2625.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

docker/plugin-setup/codex-auth-relay.js

@@ -0,0 +1,36 @@
+#!/usr/bin/env node
+/**
+ * Codex OAuth login relay for the hardened harness.
+ *
+ * `codex login` binds its callback server to 127.0.0.1:1455 inside the
+ * container. A Docker port publish forwards to the container interface, not
+ * loopback, so the host browser's redirect to http://localhost:1455 is
+ * refused. This bridges the published interface to loopback:
+ *
+ *   host 127.0.0.1:1455 -> container 0.0.0.0:1456 (this relay) -> 127.0.0.1:1455
+ *
+ * Run inside the networked session before `codex login`:
+ *   node /ecc/docker/plugin-setup/codex-auth-relay.js &
+ *
+ * Env: ECC_RELAY_LISTEN (default 1456), ECC_RELAY_TARGET (default 1455).
+ */
+
+'use strict';
+
+const net = require('net');
+
+const listenPort = Number(process.env.ECC_RELAY_LISTEN || 1456);
+const targetPort = Number(process.env.ECC_RELAY_TARGET || 1455);
+
+net.createServer(client => {
+  const upstream = net.connect(targetPort, '127.0.0.1');
+  client.pipe(upstream).pipe(client);
+  const drop = () => {
+    client.destroy();
+    upstream.destroy();
+  };
+  client.on('error', drop);
+  upstream.on('error', drop);
+}).listen(listenPort, '0.0.0.0', () => {
+  console.log(`codex-auth-relay: 0.0.0.0:${listenPort} -> 127.0.0.1:${targetPort}`);
+});

docker/plugin-setup/compose.yaml

@@ -76,6 +76,9 @@ services:
     profiles:
       - networked
     network_mode: default
+    # Codex OAuth callback bridge: host browser -> codex-auth-relay.js -> loopback.
+    ports:
+      - "127.0.0.1:1455:1456"
     image: ecc-plugin-setup:debian
 
   real-cli-ubuntu: