fix: do not pass temperature to ChatGPT Codex provider (#9931)

crates/goose/src/providers/chatgpt_codex.rs

@@ -295,10 +295,6 @@ fn create_codex_request(
         payload_obj.insert("parallel_tool_calls".to_string(), json!(true));
     }
 
-    if let Some(temp) = model_config.temperature {
-        payload_obj.insert("temperature".to_string(), json!(temp));
-    }
-
     if let Some(reasoning_effort) = reasoning_effort {
         payload_obj.insert(
             "reasoning".to_string(),
@@ -1248,6 +1244,17 @@ mod tests {
         assert!(payload.get("reasoning_effort").is_none());
     }
 
+    // ChatGPT Codex does not support temperature and will return an error
+    #[test]
+    fn test_create_codex_request_omits_temperature() {
+        let config = ModelConfig::new("gpt-5.5")
+            .unwrap()
+            .with_temperature(Some(0.2));
+
+        let payload = create_codex_request(&config, "sys", &[], &[]).unwrap();
+        assert!(payload.get("temperature").is_none());
+    }
+
     #[test_case(
         JwtClaims {
             chatgpt_account_id: Some("account-1".to_string()),