feat: add codex provider via Responses API

src/services/api/codex/client.ts

@@ -0,0 +1,55 @@
+import OpenAI from 'openai'
+import { openaiAdapter } from 'src/services/providerUsage/adapters/openai.js'
+import { updateProviderBuckets } from 'src/services/providerUsage/store.js'
+import { getProxyFetchOptions } from 'src/utils/proxy.js'
+
+let cachedClient: OpenAI | null = null
+
+function wrapFetchForUsage(base: typeof fetch): typeof fetch {
+  const wrapped = async (
+    ...args: Parameters<typeof fetch>
+  ): Promise<Response> => {
+    const res = await base(...args)
+    try {
+      updateProviderBuckets('codex', openaiAdapter.parseHeaders(res.headers))
+    } catch {
+      // Usage tracking must not affect the request path.
+    }
+    return res
+  }
+  return wrapped as unknown as typeof fetch
+}
+
+export function getCodexClient(options?: {
+  maxRetries?: number
+  fetchOverride?: typeof fetch
+}): OpenAI {
+  if (cachedClient && !options?.fetchOverride) {
+    return cachedClient
+  }
+
+  const apiKey = process.env.CODEX_API_KEY || ''
+  const baseURL = process.env.CODEX_BASE_URL
+  const baseFetch = options?.fetchOverride ?? (globalThis.fetch as typeof fetch)
+  const wrappedFetch = wrapFetchForUsage(baseFetch)
+
+  const client = new OpenAI({
+    apiKey,
+    ...(baseURL && { baseURL }),
+    maxRetries: options?.maxRetries ?? 0,
+    timeout: parseInt(process.env.API_TIMEOUT_MS || String(600 * 1000), 10),
+    dangerouslyAllowBrowser: true,
+    fetchOptions: getProxyFetchOptions({ forAnthropicAPI: false }),
+    fetch: wrappedFetch,
+  })
+
+  if (!options?.fetchOverride) {
+    cachedClient = client
+  }
+
+  return client
+}
+
+export function clearCodexClientCache(): void {
+  cachedClient = null
+}