feat: add explicit content-length header to non-streamed item list response

Co-authored-by: aider (openai/andrew/openrouter/deepseek/deepseek-chat-v3.1) <aider@aider.chat>

src/modes/server/api/item.rs

@@ -35,7 +35,7 @@ use crate::modes::server::common::{AppState, ApiResponse, ItemInfo, TagsQuery, L
 pub async fn handle_list_items(
     State(state): State<AppState>,
     Query(params): Query<ListItemsQuery>,
-) -> Result<Json<ApiResponse<Vec<ItemInfo>>>, StatusCode> {
+) -> Result<Response, StatusCode> {
     let tags: Vec<String> = params
         .tags
         .as_ref()
@@ -93,7 +93,23 @@ pub async fn handle_list_items(
         error: None,
     };
 
-    Ok(Json(response))
+    // Serialize to JSON to get the exact length
+    let json_response = match serde_json::to_vec(&response) {
+        Ok(data) => data,
+        Err(e) => {
+            warn!("Failed to serialize response: {}", e);
+            return Err(StatusCode::INTERNAL_SERVER_ERROR);
+        }
+    };
+    
+    // Build response with explicit Content-Length
+    let response = Response::builder()
+        .header(header::CONTENT_TYPE, "application/json")
+        .header(header::CONTENT_LENGTH, json_response.len().to_string())
+        .body(axum::body::Body::from(json_response))
+        .map_err(|_| StatusCode::INTERNAL_SERVER_ERROR)?;
+    
+    Ok(response)
 }
 
 /// Handle as_meta=true response by returning JSON with metadata and content