refactor: eliminate SettingsResponse struct, serialize UserSettings directly

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/src/handlers/settings.rs

@@ -11,7 +11,7 @@ use crate::app_state::AppState;
 use crate::db;
 use crate::errors::AppError;
 use crate::middleware::auth::AuthUser;
-use crate::models::settings::{SettingsResponse, UpdateSettingsRequest};
+use crate::models::settings::UpdateSettingsRequest;
 
 /// `GET /api/v1/settings`
 ///
@@ -22,7 +22,7 @@ pub async fn get_settings(
     State(state): State<AppState>,
 ) -> Result<impl IntoResponse, AppError> {
     let settings = db::settings::get_or_create_default(&state.pool, auth_user.id).await?;
-    Ok(Json(SettingsResponse::from(settings)))
+    Ok(Json(settings))
 }
 
 /// `PUT /api/v1/settings`
@@ -38,5 +38,5 @@ pub async fn update_settings(
 
     let settings = db::settings::upsert(&state.pool, auth_user.id, &body).await?;
     tracing::info!(user_id = %auth_user.id, "Settings updated");
-    Ok(Json(SettingsResponse::from(settings)))
+    Ok(Json(settings))
 }

backend/src/models/settings.rs

@@ -7,6 +7,7 @@ use uuid::Uuid;
 /// User settings record from the database.
 #[derive(Debug, Clone, Serialize)]
 pub struct UserSettings {
+    #[serde(skip_serializing)]
     pub user_id: Uuid,
     pub theme: String,
     pub max_age_days: i32,
@@ -23,51 +24,10 @@ pub struct UserSettings {
     pub ai_model_websearch: String,
     pub rate_limit_max_requests: Option<i32>,
     pub rate_limit_time_window_seconds: Option<i32>,
+    #[serde(skip_serializing)]
     pub updated_at: DateTime<Utc>,
 }
 
-/// Response shape for `GET /api/v1/settings`.
-#[derive(Debug, Serialize)]
-pub struct SettingsResponse {
-    pub theme: String,
-    pub max_age_days: i32,
-    pub categories: Vec<String>,
-    pub max_items_per_category: i32,
-    pub max_articles_per_source: i32,
-    pub use_llm_for_source_links: bool,
-    pub use_brave_search: bool,
-    pub article_history_days: i32,
-    pub batch_size: i32,
-    pub search_agent_behavior: String,
-    pub ai_provider: String,
-    pub ai_model: String,
-    pub ai_model_websearch: String,
-    pub rate_limit_max_requests: Option<i32>,
-    pub rate_limit_time_window_seconds: Option<i32>,
-}
-
-impl From<UserSettings> for SettingsResponse {
-    fn from(s: UserSettings) -> Self {
-        Self {
-            theme: s.theme,
-            max_age_days: s.max_age_days,
-            categories: s.categories,
-            max_items_per_category: s.max_items_per_category,
-            max_articles_per_source: s.max_articles_per_source,
-            use_llm_for_source_links: s.use_llm_for_source_links,
-            use_brave_search: s.use_brave_search,
-            article_history_days: s.article_history_days,
-            batch_size: s.batch_size,
-            search_agent_behavior: s.search_agent_behavior,
-            ai_provider: s.ai_provider,
-            ai_model: s.ai_model,
-            ai_model_websearch: s.ai_model_websearch,
-            rate_limit_max_requests: s.rate_limit_max_requests,
-            rate_limit_time_window_seconds: s.rate_limit_time_window_seconds,
-        }
-    }
-}
-
 /// Request body for `PUT /api/v1/settings`.
 #[derive(Debug, Deserialize)]
 pub struct UpdateSettingsRequest {