refactor: extract GrpcUsage::into_api_usage to DRY up h2_handler

src/mitm/proto.rs

@@ -72,6 +72,29 @@ pub struct GrpcUsage {
     pub response_id: Option<String>,
 }
 
+impl GrpcUsage {
+    /// Convert to a full `ApiUsage` record, attaching the gRPC method path.
+    pub fn into_api_usage(self, grpc_method: String) -> super::store::ApiUsage {
+        super::store::ApiUsage {
+            input_tokens: self.input_tokens,
+            output_tokens: self.output_tokens,
+            thinking_output_tokens: self.thinking_output_tokens,
+            response_output_tokens: self.response_output_tokens,
+            cache_creation_input_tokens: self.cache_write_tokens,
+            cache_read_input_tokens: self.cache_read_tokens,
+            model: self.model,
+            api_provider: self.api_provider,
+            grpc_method: Some(grpc_method),
+            stop_reason: None,
+            total_cost_usd: None,
+            captured_at: std::time::SystemTime::now()
+                .duration_since(std::time::UNIX_EPOCH)
+                .unwrap_or_default()
+                .as_secs(),
+        }
+    }
+}
+
 /// Extract gRPC message frames from a buffer.
 ///
 /// A gRPC message is: