App Server - Model does not exist or you do not have access to it.

[reidbarber]

I'm trying out Codex App Server and successfully authenticated, but when I try starting a turn, I get this error

Error: {"message":"stream disconnected before completion: The model `gpt-5.3-codex` does not exist or you do not have access to it.","codexErrorInfo":"other","additionalDetails":null}

Steps to reproduce:

1. initialize: succeeds
2. thread/start: succeeds
3. turn/start: starts successfully
4. failure occurs right after, while streaming/completing that turn.

I confirmed via model/list that I have access to [ "gpt-5.3-codex", "gpt-5.2-codex", "gpt-5.1-codex-max", "gpt-5.2", "gpt-5.1-codex-mini" ].

Do I need to be added to a known clients list? I couldn't find a link for that.