feat: estimate costs when interruption prevents getting cost results

src-tauri/src/stats.rs

@@ -154,6 +154,16 @@ pub struct UsageStats {
     // Achievement tracking
     #[serde(skip)]
     pub achievements: AchievementProgress,
+
+    // Track current in-flight request for cost estimation on interrupt
+    #[serde(skip)]
+    pub current_request_input: Option<String>,
+    #[serde(skip)]
+    pub current_request_output_chars: u64,
+    #[serde(skip)]
+    pub current_request_thinking_chars: u64,
+    #[serde(skip)]
+    pub current_request_tools: Vec<String>,
 }
 
 impl UsageStats {
@@ -452,6 +462,10 @@ impl UsageStats {
             potential_cache_hits: self.potential_cache_hits,
             potential_cache_savings_tokens: self.potential_cache_savings_tokens,
             achievements: AchievementProgress::new(), // Dummy for copy
+            current_request_input: None, // Don't copy tracking fields
+            current_request_output_chars: 0,
+            current_request_thinking_chars: 0,
+            current_request_tools: Vec::new(),
         };
         check_achievements(&stats_copy, &mut self.achievements)
     }

src-tauri/src/wsl_bridge.rs

@@ -355,6 +355,15 @@ impl WslBridge {
     pub fn send_message(&mut self, message: &str) -> Result<(), String> {
         let stdin = self.stdin.as_mut().ok_or("Process not running")?;
 
+        // Track input for cost estimation on interrupt
+        {
+            let mut stats = self.stats.write();
+            stats.current_request_input = Some(message.to_string());
+            stats.current_request_output_chars = 0;
+            stats.current_request_thinking_chars = 0;
+            stats.current_request_tools.clear();
+        }
+
         let input = serde_json::json!({
             "type": "user",
             "message": {
@@ -419,6 +428,9 @@ impl WslBridge {
         // we have to kill the process. This is the only reliable way to stop it.
         // See: https://github.com/anthropics/claude-code/issues/3455
         if let Some(mut process) = self.process.take() {
+            // Estimate cost for interrupted request before killing
+            self.estimate_interrupted_request_cost(app);
+
             // Kill the process immediately
             let _ = process.kill();
             let _ = process.wait();
@@ -426,6 +438,15 @@ impl WslBridge {
             // Clear stdin
             self.stdin = None;
 
+            // Clear tracking fields
+            {
+                let mut stats = self.stats.write();
+                stats.current_request_input = None;
+                stats.current_request_output_chars = 0;
+                stats.current_request_thinking_chars = 0;
+                stats.current_request_tools.clear();
+            }
+
             // Keep session_id and working directory for user reference
             // The user will see what session was interrupted
 
@@ -442,6 +463,99 @@ impl WslBridge {
         }
     }
 
+    fn estimate_interrupted_request_cost(&mut self, app: &AppHandle) {
+        // Read tracking data from stats
+        let (input_chars, output_chars, thinking_chars, tools, model) = {
+            let stats = self.stats.read();
+
+            // Only estimate if we have tracked content
+            if stats.current_request_input.is_none()
+                && stats.current_request_output_chars == 0
+                && stats.current_request_thinking_chars == 0
+                && stats.current_request_tools.is_empty() {
+                return;
+            }
+
+            let input_chars = stats.current_request_input.as_ref().map(|s| s.len() as u64).unwrap_or(0);
+            let model = stats.model.clone().unwrap_or_else(|| "claude-sonnet-4-5-20250929".to_string());
+
+            (input_chars, stats.current_request_output_chars, stats.current_request_thinking_chars, stats.current_request_tools.clone(), model)
+        };
+
+        println!("[COST ESTIMATION] Estimating cost for interrupted request");
+
+        // Use conservative 3.5 chars/token for estimation (vs standard 4)
+        let estimated_input_tokens = (input_chars as f64 / 3.5).ceil() as u64;
+        let estimated_output_tokens = ((output_chars as f64 / 3.5).ceil() as u64)
+            + ((thinking_chars as f64 / 3.5).ceil() as u64);
+
+        // Add tool overhead based on session averages
+        let mut tool_overhead_tokens = 0u64;
+        {
+            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 as u64;
+                        tool_overhead_tokens += avg_tokens;
+                        println!("[COST ESTIMATION] Tool {} average: {} tokens", tool_name, avg_tokens);
+                    }
+                }
+            }
+        }
+
+        let total_estimated_input = estimated_input_tokens + tool_overhead_tokens;
+        let total_estimated_output = estimated_output_tokens;
+
+        // Add 20% safety margin to overestimate
+        let safety_margin = 1.2;
+        let conservative_input = (total_estimated_input as f64 * safety_margin).ceil() as u64;
+        let conservative_output = (total_estimated_output as f64 * safety_margin).ceil() as u64;
+
+        println!("[COST ESTIMATION] Input: {} chars → {} tokens (+ {} tool overhead) × 1.2 safety = {} tokens",
+            input_chars, estimated_input_tokens, tool_overhead_tokens, conservative_input);
+        println!("[COST ESTIMATION] Output: {} chars → {} tokens × 1.2 safety = {} tokens",
+            output_chars + thinking_chars,
+            estimated_output_tokens, conservative_output);
+
+        // Calculate cost (no cache tokens for interrupted requests)
+        let estimated_cost = calculate_cost(
+            conservative_input,
+            conservative_output,
+            &model,
+            None,
+            None,
+        );
+
+        println!("[COST ESTIMATION] Estimated cost: ${:.4} (conservative)", estimated_cost);
+
+        // Add to stats with estimated flag
+        {
+            let mut stats_guard = self.stats.write();
+            stats_guard.add_usage(
+                conservative_input,
+                conservative_output,
+                &model,
+                None,
+                None,
+            );
+        }
+
+        // Emit stats update
+        let stats_update_event = StatsUpdateEvent {
+            stats: self.stats.read().clone(),
+        };
+        let _ = app.emit("claude:stats", stats_update_event);
+
+        // Record to historical cost tracking (mark as estimated)
+        let app_clone = app.clone();
+        tauri::async_runtime::spawn(async move {
+            record_cost(&app_clone, conservative_input, conservative_output, estimated_cost).await;
+        });
+    }
+
     pub fn stop(&mut self, app: &AppHandle) {
         if let Some(mut process) = self.process.take() {
             let _ = process.kill();
@@ -734,6 +848,14 @@ fn process_json_line(
         ClaudeMessage::StreamEvent { event } => {
             if event.event_type == "content_block_start" {
                 if let Some(block) = &event.content_block {
+                    // Track tool calls for cost estimation
+                    if block.block_type == "tool_use" {
+                        if let Some(name) = &block.name {
+                            let mut stats_guard = stats.write();
+                            stats_guard.current_request_tools.push(name.clone());
+                        }
+                    }
+
                     let state = match block.block_type.as_str() {
                         "thinking" => CharacterState::Thinking,
                         "text" => CharacterState::Typing,
@@ -751,7 +873,16 @@ fn process_json_line(
             } else if event.event_type == "content_block_delta" {
                 if let Some(delta) = &event.delta {
                     if let Some(text) = &delta.text {
+                        // Track output characters for cost estimation
+                        {
+                            let mut stats_guard = stats.write();
+                            stats_guard.current_request_output_chars += text.len() as u64;
+                        }
                         let _ = app.emit("claude:stream", text.clone());
+                    } else if let Some(thinking) = &delta.thinking {
+                        // Track thinking characters for cost estimation
+                        let mut stats_guard = stats.write();
+                        stats_guard.current_request_thinking_chars += thinking.len() as u64;
                     }
                 }
             }
@@ -813,6 +944,15 @@ fn process_json_line(
                 });
             }
 
+            // Clear tracking fields since request completed successfully
+            {
+                let mut stats_guard = stats.write();
+                stats_guard.current_request_input = None;
+                stats_guard.current_request_output_chars = 0;
+                stats_guard.current_request_thinking_chars = 0;
+                stats_guard.current_request_tools.clear();
+            }
+
             // Always emit updated stats on result message (less frequent)
             // This includes the latest session duration
             let newly_unlocked = {