Persist one browser user agent for Axios and WebSockets

lib/http-client.ts

@@ -0,0 +1,36 @@
+/** All application Axios imports belong here. New calls and axios.create()
+ *  clients inherit the instance's browser identity, proxy and timeout. */
+import axios, { type AxiosInstance } from 'axios';
+import { applyBrokerHttpDefaults, applyBrokerProxy } from './outbound-proxy';
+import { getRequestUserAgent } from './request-user-agent';
+
+const g = globalThis as typeof globalThis & { __configuredHttpClients?: WeakSet<AxiosInstance> };
+const configured = g.__configuredHttpClients ??= new WeakSet<AxiosInstance>();
+
+function configure<T extends AxiosInstance>(client: T): T {
+    if (configured.has(client)) return client;
+    applyBrokerHttpDefaults(client.defaults);
+    // Builds import route modules but must not choose an instance's identity.
+    if (process.env.NEXT_PHASE !== 'phase-production-build') {
+        client.defaults.headers.common['User-Agent'] = getRequestUserAgent();
+        try {
+            applyBrokerProxy(client.defaults);
+        } catch (err) {
+            console.error(`[proxy] could not apply proxy_url at load: ${err instanceof Error ? err.message : String(err)}`);
+        }
+    }
+    client.interceptors.request.use((config) => {
+        // Force replacement even for differently cased headers or `false`.
+        // This also replaces a stale per-call UA without losing auth headers.
+        config.headers.set('User-Agent', getRequestUserAgent(), true);
+        return config;
+    }, undefined, { synchronous: true });
+
+    // Axios copies defaults into child clients, but not interceptors.
+    const create = client.create.bind(client);
+    client.create = (options) => configure(create(options));
+    configured.add(client);
+    return client;
+}
+
+export default configure(axios);