diff --git a/README.md b/README.md
index 948ae1b..3571ea3 100644
--- a/README.md
+++ b/README.md
@@ -62,6 +62,9 @@ Every role can stay `native` or select a fixed `kenari/<model-id>`. Codex main
 also supports `picker`. Codex review and subagents also support `inherit`.
 Native is always the default.
 
+For Codex, Kenari detects whether `codex login` uses ChatGPT or an API key and
+keeps native requests on the matching OpenAI upstream.
+
 Automation must set every role:
 
 ```bash
diff --git a/package.json b/package.json
index d4a9ad9..bcb41da 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@kenarihq/cli",
-  "version": "0.3.0",
+  "version": "0.3.1",
   "description": "Official kenari CLI. Route Claude Code and Codex models per process.",
   "license": "MIT",
   "type": "module",
diff --git a/src/cli.js b/src/cli.js
index a123d2a..30f72b2 100644
--- a/src/cli.js
+++ b/src/cli.js
@@ -32,7 +32,11 @@ import { gatewayBase, modelCachePath, runtimeDir } from './paths.js';
 import { genPkce, genState, buildLoopbackUrl, buildPasteUrl, startCallbackServer } from './oauth.js';
 import { resolveBinary, runWrappedTool } from './supervisor.js';
 import { buildClaudeLaunch } from './runtime/claude.js';
-import { buildCodexLaunch, loadCodexNativeModels } from './runtime/codex.js';
+import {
+  buildCodexLaunch,
+  loadCodexNativeModels,
+  resolveCodexNativeBase,
+} from './runtime/codex.js';
 import { startRouter } from './router.js';
 import { detectOrphanedV1Signatures, detectV1State, migrateV1 } from './migrate.js';
 
@@ -497,7 +501,7 @@ async function runTool(tool, args) {
   }
   const kenariBase = tool === 'codex' ? `${gatewayBase()}/v1` : gatewayBase();
   const nativeBase = tool === 'codex'
-    ? (process.env.KENARI_CODEX_NATIVE_BASE_URL || 'https://api.openai.com/v1')
+    ? resolveCodexNativeBase(binary, process.env)
     : (process.env.KENARI_CLAUDE_NATIVE_BASE_URL || 'https://api.anthropic.com');
   const runtimeBuilder = tool === 'codex' ? buildCodexLaunch : buildClaudeLaunch;
   try {
diff --git a/src/runtime/codex.js b/src/runtime/codex.js
index b6aa97e..a30ade1 100644
--- a/src/runtime/codex.js
+++ b/src/runtime/codex.js
@@ -1,10 +1,29 @@
 import { spawnSync } from 'node:child_process';
 import { KenariError } from '../store.js';
 
+export const CODEX_CHATGPT_BASE_URL = 'https://chatgpt.com/backend-api/codex';
+export const CODEX_API_BASE_URL = 'https://api.openai.com/v1';
+const CODEX_ROUTER_PROVIDER = 'kenari_router';
+
 function tomlString(value) {
   return JSON.stringify(value);
 }
 
+export function resolveCodexNativeBase(binary, env = process.env, run = spawnSync) {
+  if (env.KENARI_CODEX_NATIVE_BASE_URL) return env.KENARI_CODEX_NATIVE_BASE_URL;
+  const result = run(binary, ['login', 'status'], {
+    encoding: 'utf8',
+    env,
+    timeout: 5000,
+    windowsHide: true,
+  });
+  const output = `${result.stdout || ''}\n${result.stderr || ''}`;
+  if (/logged in using chatgpt/i.test(output)) return CODEX_CHATGPT_BASE_URL;
+  if (/logged in using (?:an )?api key/i.test(output)) return CODEX_API_BASE_URL;
+  if (env.OPENAI_API_KEY?.trim()) return CODEX_API_BASE_URL;
+  throw new KenariError('cannot determine Codex login method. Run: codex login');
+}
+
 export function loadCodexNativeModels(binary, env = process.env) {
   for (const args of [['debug', 'models'], ['debug', 'models', '--bundled']]) {
     const result = spawnSync(binary, args, {
@@ -73,8 +92,13 @@ export function buildCodexLaunch(options) {
     if (inline === null) index += 1;
   }
   const overrides = [
-    'model_provider="openai"',
-    `openai_base_url=${tomlString(options.routerUrl)}`,
+    `model_provider="${CODEX_ROUTER_PROVIDER}"`,
+    `model_providers.${CODEX_ROUTER_PROVIDER}.name="OpenAI"`,
+    `model_providers.${CODEX_ROUTER_PROVIDER}.base_url=${tomlString(options.routerUrl)}`,
+    `model_providers.${CODEX_ROUTER_PROVIDER}.wire_api="responses"`,
+    `model_providers.${CODEX_ROUTER_PROVIDER}.requires_openai_auth=true`,
+    `model_providers.${CODEX_ROUTER_PROVIDER}.supports_websockets=false`,
+    `model_providers.${CODEX_ROUTER_PROVIDER}.supports_standalone_web_search=true`,
   ];
   if (options.catalogPath) {
     overrides.push(`model_catalog_json=${tomlString(options.catalogPath)}`);
diff --git a/test/v2-runtime-supervisor.test.js b/test/v2-runtime-supervisor.test.js
index a9fe807..62837ef 100644
--- a/test/v2-runtime-supervisor.test.js
+++ b/test/v2-runtime-supervisor.test.js
@@ -5,7 +5,13 @@ import os from 'node:os';
 import path from 'node:path';
 import http from 'node:http';
 import { buildClaudeLaunch, findClaudeEnvConflicts } from '../src/runtime/claude.js';
-import { buildCodexLaunch, codexKenariModels } from '../src/runtime/codex.js';
+import {
+  CODEX_API_BASE_URL,
+  CODEX_CHATGPT_BASE_URL,
+  buildCodexLaunch,
+  codexKenariModels,
+  resolveCodexNativeBase,
+} from '../src/runtime/codex.js';
 import { resolveBinary, runWrappedTool } from '../src/supervisor.js';
 
 const originalAllowHttp = process.env.KENARI_ALLOW_HTTP;
@@ -121,7 +127,12 @@ test('Codex launch injects temporary controls before original args', () => {
   });
   assert.deepEqual(built.args.slice(-4), ['exec', '-c', 'review_model="native-review"', 'hello']);
   assert.ok(built.args.indexOf('review_model="kenari/reviewer"') < built.args.indexOf('exec'));
-  assert.ok(built.args.includes('openai_base_url="http://127.0.0.1:2"'));
+  assert.ok(built.args.includes('model_provider="kenari_router"'));
+  assert.ok(built.args.includes(
+    'model_providers.kenari_router.base_url="http://127.0.0.1:2"',
+  ));
+  assert.ok(built.args.includes('model_providers.kenari_router.requires_openai_auth=true'));
+  assert.ok(built.args.includes('model_providers.kenari_router.supports_websockets=false'));
   assert.equal(built.env.OPENAI_API_KEY, 'secret');
   assert.equal(built.env.KEEP, 'yes');
   const native = [{
@@ -140,6 +151,64 @@ test('Codex launch injects temporary controls before original args', () => {
   }), /unsafe Codex routing override/);
 });
 
+test('Codex native upstream follows the active login method', () => {
+  const cases = [
+    {
+      name: 'ChatGPT stdout',
+      result: { status: 0, stdout: 'Logged in using ChatGPT\n', stderr: '' },
+      expected: CODEX_CHATGPT_BASE_URL,
+    },
+    {
+      name: 'ChatGPT after warning',
+      result: {
+        status: 0,
+        stdout: 'Logged in using ChatGPT\n',
+        stderr: 'WARNING: could not create PATH aliases\n',
+      },
+      expected: CODEX_CHATGPT_BASE_URL,
+    },
+    {
+      name: 'API key',
+      result: { status: 0, stdout: 'Logged in using an API key\n', stderr: '' },
+      expected: CODEX_API_BASE_URL,
+    },
+  ];
+  for (const entry of cases) {
+    const calls = [];
+    const base = resolveCodexNativeBase('/bin/codex', {}, (...args) => {
+      calls.push(args);
+      return entry.result;
+    });
+    assert.equal(base, entry.expected, entry.name);
+    assert.deepEqual(calls[0].slice(0, 2), ['/bin/codex', ['login', 'status']], entry.name);
+  }
+});
+
+test('Codex native upstream override and API key fallback are deterministic', () => {
+  let calls = 0;
+  const override = resolveCodexNativeBase('/bin/codex', {
+    KENARI_CODEX_NATIVE_BASE_URL: 'https://proxy.example/v1',
+  }, () => {
+    calls += 1;
+    return {};
+  });
+  assert.equal(override, 'https://proxy.example/v1');
+  assert.equal(calls, 0);
+
+  const fallback = resolveCodexNativeBase('/bin/codex', {
+    OPENAI_API_KEY: 'sk-test',
+  }, () => ({ status: 1, stdout: '', stderr: 'Not logged in' }));
+  assert.equal(fallback, CODEX_API_BASE_URL);
+});
+
+test('Codex native upstream fails closed when login method is unknown', () => {
+  assert.throws(() => resolveCodexNativeBase(
+    '/bin/codex',
+    {},
+    () => ({ status: 1, stdout: '', stderr: 'Not logged in' }),
+  ), /cannot determine Codex login method/);
+});
+
 test('resolveBinary skips excluded wrapper and supervisor returns child exit code', async (t) => {
   const dir = fs.mkdtempSync(path.join(os.tmpdir(), 'kenari-bin-'));
   t.after(() => fs.rmSync(dir, { recursive: true, force: true }));