fix(settings): map unknown UI locales to en-US for commit prompts

Portuguese and other interface languages have no commit prompt catalog; sending pt-BR made settings fail to deserialize.

Co-authored-by: Cursor <cursoragent@cursor.com>

server/src/control/settings.rs

@@ -149,13 +149,11 @@ pub async fn update_pricing_settings(
 }
 
 fn requested_commit_locale(headers: &HeaderMap) -> CommitPromptLocale {
-    match headers
+    headers
         .get(header::ACCEPT_LANGUAGE)
         .and_then(|value| value.to_str().ok())
-    {
-        Some(value) if value.eq_ignore_ascii_case("zh-CN") => CommitPromptLocale::ZhCn,
-        _ => CommitPromptLocale::EnUs,
-    }
+        .map(CommitPromptLocale::from_interface_language)
+        .unwrap_or(CommitPromptLocale::EnUs)
 }
 
 #[cfg(test)]
@@ -170,5 +168,8 @@ mod tests {
 
         headers.insert(header::ACCEPT_LANGUAGE, "en-US".parse().unwrap());
         assert_eq!(requested_commit_locale(&headers), CommitPromptLocale::EnUs);
+
+        headers.insert(header::ACCEPT_LANGUAGE, "pt-BR".parse().unwrap());
+        assert_eq!(requested_commit_locale(&headers), CommitPromptLocale::EnUs);
     }
 }

server/src/store/settings.rs

@@ -1,5 +1,5 @@
 //! Persists application settings.
-use serde::{Deserialize, Serialize};
+use serde::{Deserialize, Deserializer, Serialize};
 
 use crate::Result;
 
@@ -105,7 +105,7 @@ impl TabSettings {
     }
 }
 
-#[derive(Clone, Copy, Debug, Default, Deserialize, PartialEq, Eq, Serialize)]
+#[derive(Clone, Copy, Debug, Default, PartialEq, Eq, Serialize)]
 pub enum CommitPromptLocale {
     #[default]
     #[serde(rename = "zh-CN")]
@@ -115,6 +115,14 @@ pub enum CommitPromptLocale {
 }
 
 impl CommitPromptLocale {
+    pub fn from_interface_language(value: &str) -> Self {
+        if value.eq_ignore_ascii_case("zh-CN") {
+            Self::ZhCn
+        } else {
+            Self::EnUs
+        }
+    }
+
     pub fn default_prompt(self) -> &'static str {
         match self {
             Self::ZhCn => DEFAULT_COMMIT_PROMPT_ZH_CN.trim(),
@@ -123,6 +131,13 @@ impl CommitPromptLocale {
     }
 }
 
+impl<'de> Deserialize<'de> for CommitPromptLocale {
+    fn deserialize<D: Deserializer<'de>>(deserializer: D) -> Result<Self, D::Error> {
+        let value = String::deserialize(deserializer)?;
+        Ok(Self::from_interface_language(&value))
+    }
+}
+
 /// User preferences for Git commit message generation.
 ///
 /// Empty `model_id` means 直连: forward the original Cursor RPC unchanged.
@@ -490,6 +505,26 @@ mod tests {
     const LEGACY_PROXY_ROW: &str =
         r#"{"mode":"system","address":"","auth_enabled":false,"username":"","password":""}"#;
 
+    #[test]
+    fn commit_prompt_locale_maps_unknown_interface_languages_to_english() {
+        assert_eq!(
+            serde_json::from_str::<CommitPromptLocale>(r#""zh-CN""#).unwrap(),
+            CommitPromptLocale::ZhCn
+        );
+        assert_eq!(
+            serde_json::from_str::<CommitPromptLocale>(r#""en-US""#).unwrap(),
+            CommitPromptLocale::EnUs
+        );
+        assert_eq!(
+            serde_json::from_str::<CommitPromptLocale>(r#""pt-BR""#).unwrap(),
+            CommitPromptLocale::EnUs
+        );
+        assert_eq!(
+            serde_json::to_string(&CommitPromptLocale::EnUs).unwrap(),
+            r#""en-US""#
+        );
+    }
+
     #[test]
     fn default_commit_prompt_follows_its_saved_locale() {
         for (prompt_locale, expected) in [