{"type":"error","status":400,"error":{"type":"invalid_request_error","message":"The 'gpt-5.5' model is not supported when using Codex with a ChatGPT account."}}

### What steps can reproduce the bug?

Codex shows my account as `Plus` in `/status`, and `gpt-5.5` is visible/selectable, but requests fail immediately with:                                                                                                           
                                                                                                                                                                                                                                  
```text                                                                                                                                                                                                                           
{"type":"error","status":400,"error":{"type":"invalid_request_error","message":"The 'gpt-5.5' model is not supported when using Codex with a ChatGPT account."}}                                                                  
                                                                                                                                                                                                                                  
Relevant context:                                                                                                                                                                                                                 
                                                                                                                                                                                                                                  
- /status shows:                                                                                                                                                                                                                  
    - OpenAI Codex (v0.125.0)                                                                                                                                                                                                     
    - Account: [redacted] (Plus)                                                                                                                                                                                                  
    - Model: gpt-5.4                                                                                                                                                                                                              
    - Session: 019dc8f0-8c9b-70a0-9147-d456244229e0                                                                                                                                                                               
- I am signed in with a ChatGPT account, not an API key.                                                                                                                                                                          
- The model picker offers gpt-5.5, but execution is rejected by the backend.                                                                                                                                                      
                                                                                                                                                                                                                                  
This looks like an entitlement / account-sync inconsistency:                                                                                                                                                                      
                                                                                                                                                                                                                                  
- account tier appears to be Plus                                                                                                                                                                                                 
- but gpt-5.5 is still rejected as unsupported for ChatGPT account auth

### What is the expected behavior?

1. Sign in to Codex CLI with a ChatGPT Plus account.                                                                                                                                                                              
2. Confirm in `/status` that the account is shown as `Plus`.                                                                                                                                                                      
3. Select `gpt-5.5` in the model picker.                                                                                                                                                                                          
4. Send a simple prompt such as: hi                                                                                                                                                                                                                                                                                                                                                                        
5. The request fails immediately with:                                                                                                                                                                                            
                                                                                                                                                                                                                                  
{"type":"error","status":400,"error":{"type":"invalid_request_error","message":"The 'gpt-5.5' model is not supported when using Codex with a ChatGPT account."}}                                                                  
                                                                                                                                                                                                                                  
Thread id:                                                                                                                                                                                                                        
019dc8f0-8c9b-70a0-9147-d456244229e0

### Additional information

If `gpt-5.5` is shown as selectable for a ChatGPT Plus account, requests should run successfully.                                                                                                                                 

At minimum, the model picker and backend entitlements should be consistent:                                                                                                                                                       
- either `gpt-5.5` should not be shown                                                                                                                                                                                            
- or it should be executable for the signed-in Plus account