Add Codex WebSocket support

README.md

@@ -51,6 +51,8 @@ fx
 
 The OpenAI Codex route uses ChatGPT subscription access directly and never sends its OAuth token to Vercel AI Gateway. The session is stored privately at `~/.fx/chatgpt-auth.json` and refreshed when needed. On supported Codex models, `/fast` requests OpenAI's priority service tier and consumes ChatGPT credits at the higher Fast mode rate.
 
+Codex uses HTTP streaming by default. To prefer the WebSocket transport, start fx with `FX_CODEX_TRANSPORT=websocket`. If connection setup fails before the request can be delivered, fx completes that turn over HTTP and keeps using HTTP for the rest of the process. It never replays a request whose delivery is uncertain. WebSocket sessions retain compatible connections and continuation state; concurrent requests use separate ordered lanes rather than sharing one response stream. Each session identity retains at most four lanes by default, and the process retains at most 32 lanes across identities. Set `FX_CODEX_WEBSOCKET_MAX_LANES` or `FX_CODEX_WEBSOCKET_MAX_SLOTS` to a positive integer to choose different limits.
+
 The Grok route uses subscription access directly at xAI and never sends its OAuth token to Vercel AI Gateway or OpenAI. Its session is stored privately at `~/.fx/grok-auth.json`, refreshed when needed, and used only with the authenticated xAI catalog and Responses API.
 
 To use an AI Gateway API key instead: