feat(deploy): Cloudflare Worker proxies /api/codex to a clean-IP box backend

OpenAI's Cloudflare challenges datacenter IPs (Workers get 403 on
chatgpt.com/backend-api; residential/box IPs get 200 — verified). So the live
demo now runs the directRunner backend on an ascii.dev 'box' VM (clean IP,
always-on via ttlSeconds:null) exposed at a public HTTPS URL, and the Cloudflare
Worker reverse-proxies /api/codex/* to it. The browser only ever talks to
codexauth.sharenow.today, so the HttpOnly session cookie round-trips same-origin.

Verified live end-to-end: SPA serves, /session + /login/start proxy to the box
and return a real device code; the box IP reaches chatgpt.com (200) so output
actually streams.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: sng-asyncfunc

deploy/cloudflare/worker.ts

@@ -1,21 +1,21 @@
 /**
- * Cloudflare Worker that hosts the whole CodexAuth demo:
- *   - /api/codex/*  → the contract handler + directRunner (pure fetch, no CLI),
- *                     with session/token state persisted to KV
- *   - everything else → the React SPA from the ASSETS binding
+ * Cloudflare Worker for the CodexAuth demo.
  *
- * This is the serverless deploy: no Node binary, no persistent process. Built on
- * the same codex-auth/backend the Express/Next adapters use.
+ *   - /api/codex/*  → reverse-proxied to the backend running on a "box" VM
+ *                     (a clean residential-ish IP). The directRunner there can
+ *                     reach chatgpt.com/backend-api, which a Worker's datacenter
+ *                     IP cannot (OpenAI's Cloudflare challenges it). The browser
+ *                     only ever talks to codexauth.sharenow.today — same-origin,
+ *                     so the HttpOnly session cookie round-trips normally.
+ *   - everything else → the React SPA from the ASSETS binding.
+ *
+ * CODEX_BACKEND_ORIGIN (var) is the box's public HTTPS origin.
  */
-import { handleCodexRequestKV } from "../../src/backend/cloudflare/kvSessionStore.js";
-import { directRunner } from "../../src/backend/direct/index.js";
-import type { KVNamespace, Fetcher } from "@cloudflare/workers-types";
+import type { Fetcher } from "@cloudflare/workers-types";
 
 interface Env {
   ASSETS: Fetcher;
-  CODEX_SESSIONS: KVNamespace;
-  COOKIE_SECRET: string;
-  CODEX_MODEL?: string;
+  CODEX_BACKEND_ORIGIN: string;
 }
 
 const BASE_PATH = "/api/codex";
@@ -25,22 +25,29 @@ export default {
     const url = new URL(request.url);
 
     if (url.pathname.startsWith(BASE_PATH)) {
-      if (!env.COOKIE_SECRET || env.COOKIE_SECRET.length < 16) {
-        return new Response("COOKIE_SECRET is not configured", { status: 500 });
-      }
-      return handleCodexRequestKV(request, {
-        kv: env.CODEX_SESSIONS,
-        cookieSecret: env.COOKIE_SECRET,
-        basePath: BASE_PATH,
-        // Force gpt-5.5: it's the model the ChatGPT-account responses backend
-        // accepts. Account-aware /models discovery is often Cloudflare-blocked
-        // from a Worker's datacenter IP, and the generic fallbacks (gpt-5-codex,
-        // gpt-5) are rejected — verified live.
-        runner: directRunner({ models: [env.CODEX_MODEL ?? "gpt-5.5"] }),
+      const backend = env.CODEX_BACKEND_ORIGIN?.replace(/\/+$/, "");
+      if (!backend) return new Response("CODEX_BACKEND_ORIGIN not set", { status: 500 });
+
+      const target = new URL(backend);
+      target.pathname = url.pathname;
+      target.search = url.search;
+
+      // Forward method, headers (incl. cookie), and body. Preserve streaming both
+      // ways (NDJSON for /run/stream).
+      const proxied = new Request(target.toString(), {
+        method: request.method,
+        headers: request.headers,
+        body: request.method === "GET" || request.method === "HEAD" ? undefined : request.body,
+        redirect: "manual",
+      });
+      const resp = await fetch(proxied);
+      return new Response(resp.body, {
+        status: resp.status,
+        statusText: resp.statusText,
+        headers: resp.headers,
       });
     }
 
-    // Everything else is the static SPA.
     return env.ASSETS.fetch(request);
   },
 };

deploy/cloudflare/wrangler.jsonc

@@ -3,27 +3,21 @@
   "name": "codexauth",
   "main": "worker.ts",
   "compatibility_date": "2025-06-01",
-  "compatibility_flags": ["nodejs_compat"],
   "workers_dev": false,
   "assets": {
     "directory": "./public",
     "binding": "ASSETS",
     "not_found_handling": "single-page-application",
     "run_worker_first": ["/api/*"]
   },
-  "kv_namespaces": [
-    {
-      "binding": "CODEX_SESSIONS",
-      "id": "18d05b5f9a9e470eb14e69370f15a9ff"
-    }
-  ],
   "routes": [
     {
       "pattern": "codexauth.sharenow.today",
       "custom_domain": true
     }
   ],
   "vars": {
-    "CODEX_MODEL": "gpt-5.5"
+    // The box VM's public HTTPS origin (clean IP that can reach chatgpt.com).
+    "CODEX_BACKEND_ORIGIN": "https://surah-waxer-ploidy-3000.on.ascii.dev"
   }
 }