fix(sync): align ChatGPT and service tier parity

code-rs/chatgpt/src/chatgpt_client.rs

@@ -24,7 +24,11 @@ pub(crate) async fn chatgpt_get_request<T: DeserializeOwned>(
 
     // Make direct HTTP request to ChatGPT backend API with the token
     let client = code_core::http_client::build_http_client();
-    let url = format!("{chatgpt_base_url}{path}");
+    let url = format!(
+        "{}/{}",
+        chatgpt_base_url.trim_end_matches('/'),
+        path.trim_start_matches('/')
+    );
 
     let token = auth.get_token_data().await?;
     let account_id = token.account_id.ok_or_else(|| {

code-rs/core/src/client.rs

@@ -768,7 +768,8 @@ impl ModelClient {
                 include,
                 service_tier: match self.config.service_tier {
                     Some(ServiceTier::Fast) => Some("priority".to_string()),
-                    _ => None,
+                    Some(service_tier) => Some(service_tier.to_string()),
+                    None => None,
                 },
                 prompt_cache_key: Some(session_id_str.clone()),
             };
@@ -1244,7 +1245,8 @@ impl ModelClient {
                 include,
                 service_tier: match self.config.service_tier {
                     Some(ServiceTier::Fast) => Some("priority".to_string()),
-                    _ => None,
+                    Some(service_tier) => Some(service_tier.to_string()),
+                    None => None,
                 },
                 // Use a stable per-process cache key (session id). With store=false this is inert.
                 prompt_cache_key: Some(session_id_str.clone()),

code-rs/core/src/config.rs

@@ -454,6 +454,7 @@ pub struct Config {
     /// Optional service tier preference for model requests.
     ///
     /// `Some(Fast)` sends `service_tier=priority` to the Responses API.
+    /// `Some(Flex)` sends `service_tier=flex` to the Responses API.
     /// `None` sends no override (legacy standard behavior).
     pub service_tier: Option<ServiceTier>,
 
@@ -1321,6 +1322,7 @@ impl Config {
 
         let service_tier = match config_profile.service_tier.or(cfg.service_tier) {
             Some(ServiceTier::Fast) => Some(ServiceTier::Fast),
+            Some(ServiceTier::Flex) => Some(ServiceTier::Flex),
             Some(ServiceTier::Standard) => None,
             None => None,
         };
@@ -3433,6 +3435,23 @@ mod agent_merge_tests {
         Ok(())
     }
 
+    #[test]
+    fn service_tier_flex_preserves_override() -> anyhow::Result<()> {
+        let code_home = TempDir::new()?;
+        let cfg = toml::from_str::<ConfigToml>(r#"service_tier = "flex""#)?;
+        let config = Config::load_from_base_config_with_overrides(
+            cfg,
+            ConfigOverrides {
+                cwd: Some(code_home.path().to_path_buf()),
+                ..Default::default()
+            },
+            code_home.path().to_path_buf(),
+        )?;
+
+        assert_eq!(config.service_tier, Some(ServiceTier::Flex));
+        Ok(())
+    }
+
     #[test]
     fn service_tier_standard_disables_override() -> anyhow::Result<()> {
         let code_home = TempDir::new()?;

code-rs/core/src/config_types.rs

@@ -1500,6 +1500,7 @@ pub enum ServiceTier {
     /// Legacy compatibility value for older local config files.
     Standard,
     Fast,
+    Flex,
 }
 
 #[derive(Debug, Serialize, Deserialize, Clone, Copy, PartialEq, Eq, Display)]

code-rs/protocol/src/config_types.rs

@@ -123,6 +123,7 @@ pub enum ServiceTier {
     /// Legacy compatibility value for older local config files.
     Standard,
     Fast,
+    Flex,
 }
 
 #[derive(Debug, Serialize, Deserialize, Clone, Copy, PartialEq, Eq, Display, JsonSchema, TS)]

code-rs/tui/src/chatwidget.rs

@@ -23463,6 +23463,7 @@ Have we met every part of this goal and is there no further work to do?"#
         let persisted_service_tier = match (profile.as_deref(), self.config.service_tier) {
             (Some(_), None) => Some("standard"),
             (_, Some(ServiceTier::Fast)) => Some("fast"),
+            (_, Some(ServiceTier::Flex)) => Some("flex"),
             (_, Some(ServiceTier::Standard)) => Some("standard"),
             (_, None) => None,
         };