feat: implement provider credit tracking and balance management

- Added 'credit_balance' and 'low_credit_threshold' to 'provider_configs' table.
- Updated dashboard backend to support reading and updating provider credits.
- Implemented real-time credit deduction from provider balances on successful requests.
- Added visual balance indicators and configuration modal to the 'Providers' dashboard tab.

src/dashboard/mod.rs

@@ -536,7 +536,7 @@ async fn handle_get_providers(State(state): State<DashboardState>) -> Json<ApiRe
     let pool = &state.app_state.db_pool;
     
     // Load all overrides from database
-    let db_configs_result = sqlx::query("SELECT id, enabled, base_url FROM provider_configs")
+    let db_configs_result = sqlx::query("SELECT id, enabled, base_url, credit_balance, low_credit_threshold FROM provider_configs")
         .fetch_all(pool)
         .await;
         
@@ -546,7 +546,9 @@ async fn handle_get_providers(State(state): State<DashboardState>) -> Json<ApiRe
             let id: String = row.get("id");
             let enabled: bool = row.get("enabled");
             let base_url: Option<String> = row.get("base_url");
-            db_configs.insert(id, (enabled, base_url));
+            let balance: f64 = row.get("credit_balance");
+            let threshold: f64 = row.get("low_credit_threshold");
+            db_configs.insert(id, (enabled, base_url, balance, threshold));
         }
     }
 
@@ -566,12 +568,17 @@ async fn handle_get_providers(State(state): State<DashboardState>) -> Json<ApiRe
             _ => (false, "".to_string(), "Unknown"),
         };
 
+        let mut balance = 0.0;
+        let mut threshold = 5.0;
+
         // Apply database overrides
-        if let Some((db_enabled, db_url)) = db_configs.get(id) {
+        if let Some((db_enabled, db_url, db_balance, db_threshold)) = db_configs.get(id) {
             enabled = *db_enabled;
             if let Some(url) = db_url {
                 base_url = url.clone();
             }
+            balance = *db_balance;
+            threshold = *db_threshold;
         }
 
         // Find models for this provider in registry
@@ -606,6 +613,8 @@ async fn handle_get_providers(State(state): State<DashboardState>) -> Json<ApiRe
             "status": status,
             "models": models,
             "base_url": base_url,
+            "credit_balance": balance,
+            "low_credit_threshold": threshold,
             "last_used": None::<String>,
         }));
     }
@@ -625,6 +634,8 @@ struct UpdateProviderRequest {
     enabled: bool,
     base_url: Option<String>,
     api_key: Option<String>,
+    credit_balance: Option<f64>,
+    low_credit_threshold: Option<f64>,
 }
 
 async fn handle_update_provider(
@@ -637,12 +648,14 @@ async fn handle_update_provider(
     // Update or insert into database
     let result = sqlx::query(
         r#"
-        INSERT INTO provider_configs (id, display_name, enabled, base_url, api_key)
-        VALUES (?, ?, ?, ?, ?)
+        INSERT INTO provider_configs (id, display_name, enabled, base_url, api_key, credit_balance, low_credit_threshold)
+        VALUES (?, ?, ?, ?, ?, ?, ?)
         ON CONFLICT(id) DO UPDATE SET
             enabled = excluded.enabled,
             base_url = excluded.base_url,
             api_key = COALESCE(excluded.api_key, provider_configs.api_key),
+            credit_balance = COALESCE(excluded.credit_balance, provider_configs.credit_balance),
+            low_credit_threshold = COALESCE(excluded.low_credit_threshold, provider_configs.low_credit_threshold),
             updated_at = CURRENT_TIMESTAMP
         "#
     )
@@ -651,6 +664,8 @@ async fn handle_update_provider(
     .bind(payload.enabled)
     .bind(&payload.base_url)
     .bind(&payload.api_key)
+    .bind(payload.credit_balance)
+    .bind(payload.low_credit_threshold)
     .execute(pool)
     .await;
 

src/database/mod.rs

@@ -87,6 +87,8 @@ async fn run_migrations(pool: &DbPool) -> Result<()> {
             enabled BOOLEAN DEFAULT TRUE,
             base_url TEXT,
             api_key TEXT,
+            credit_balance REAL DEFAULT 0.0,
+            low_credit_threshold REAL DEFAULT 5.0,
             updated_at DATETIME DEFAULT CURRENT_TIMESTAMP
         )
         "#

src/logging/mod.rs

@@ -56,6 +56,8 @@ impl RequestLogger {
 
     /// Insert a log entry into the database
     async fn insert_log(pool: &SqlitePool, log: RequestLog) -> Result<(), sqlx::Error> {
+        let mut tx = pool.begin().await?;
+
         sqlx::query(
             r#"
             INSERT INTO llm_requests 
@@ -65,7 +67,7 @@ impl RequestLogger {
         )
         .bind(log.timestamp)
         .bind(log.client_id)
-        .bind(log.provider)
+        .bind(&log.provider)
         .bind(log.model)
         .bind(log.prompt_tokens as i64)
         .bind(log.completion_tokens as i64)
@@ -77,9 +79,22 @@ impl RequestLogger {
         .bind(log.duration_ms as i64)
         .bind(None::<String>) // request_body - TODO: store serialized request
         .bind(None::<String>) // response_body - TODO: store serialized response or error
-        .execute(pool)
+        .execute(&mut *tx)
         .await?;
 
+        // Deduct from provider balance if successful
+        if log.cost > 0.0 {
+            sqlx::query(
+                "UPDATE provider_configs SET credit_balance = credit_balance - ? WHERE id = ?"
+            )
+            .bind(log.cost)
+            .bind(&log.provider)
+            .execute(&mut *tx)
+            .await?;
+        }
+
+        tx.commit().await?;
+
         Ok(())
     }
 }