diff --git a/src-tauri/src/sessions.rs b/src-tauri/src/sessions.rs
index 42dca83..f325b0a 100644
--- a/src-tauri/src/sessions.rs
+++ b/src-tauri/src/sessions.rs
@@ -81,7 +81,7 @@ pub async fn list_sessions(app: AppHandle) -> Result<Vec<SessionListItem>, Strin
     let mut items: Vec<SessionListItem> = sessions.iter().map(SessionListItem::from).collect();
 
     // Sort by last activity, most recent first
-    items.sort_by(|a, b| b.last_activity_at.cmp(&a.last_activity_at));
+    items.sort_by_key(|b| std::cmp::Reverse(b.last_activity_at));
 
     Ok(items)
 }
@@ -132,7 +132,7 @@ pub async fn search_sessions(app: AppHandle, query: String) -> Result<Vec<Sessio
         .collect();
 
     // Sort by last activity, most recent first
-    matching.sort_by(|a, b| b.last_activity_at.cmp(&a.last_activity_at));
+    matching.sort_by_key(|b| std::cmp::Reverse(b.last_activity_at));
 
     Ok(matching)
 }
@@ -348,7 +348,7 @@ mod tests {
         ];
 
         // Sort by last activity, most recent first (mimics list_sessions behavior)
-        sessions.sort_by(|a, b| b.last_activity_at.cmp(&a.last_activity_at));
+        sessions.sort_by_key(|b| std::cmp::Reverse(b.last_activity_at));
 
         assert_eq!(sessions[0].id, "new");
         assert_eq!(sessions[1].id, "old");
diff --git a/src-tauri/src/wsl_bridge.rs b/src-tauri/src/wsl_bridge.rs
index 197de82..a348301 100644
--- a/src-tauri/src/wsl_bridge.rs
+++ b/src-tauri/src/wsl_bridge.rs
@@ -920,10 +920,9 @@ impl WslBridge {
             let stats = self.stats.read();
             for tool_name in &tools {
                 if let Some(tool_stats) = stats.session_tools_usage.get(tool_name) {
-                    if tool_stats.call_count > 0 {
-                        // Use session average tokens per call for this tool
-                        let avg_tokens = (tool_stats.estimated_input_tokens + tool_stats.estimated_output_tokens)
-                            / tool_stats.call_count;
+                    if let Some(avg_tokens) = (tool_stats.estimated_input_tokens + tool_stats.estimated_output_tokens)
+                        .checked_div(tool_stats.call_count)
+                    {
                         tool_overhead_tokens += avg_tokens;
                         tracing::info!("[COST ESTIMATION] Tool {} average: {} tokens", tool_name, avg_tokens);
                     }