feat: implement length parameter handling in stream_item_content_by_id

Co-authored-by: aider (openai/andrew/openrouter/qwen/qwen3-coder) <aider@aider.chat>

src/services/async_item_service.rs

@@ -57,7 +57,7 @@ impl AsyncItemService {
         item_id: i64,
         allow_binary: bool,
         _offset: u64,
-        _length: u64,
+        length: u64,
     ) -> Result<(std::pin::Pin<Box<dyn tokio_stream::Stream<Item = Result<tokio_util::bytes::Bytes, std::io::Error>> + Send>>, String), CoreError> {
         // Get the item content synchronously
         let item_with_content = self.get_item_content(item_id).await?;
@@ -82,8 +82,11 @@ impl AsyncItemService {
             .map(|s| s.to_string())
             .unwrap_or_else(|| "application/octet-stream".to_string());
         
-        // Convert content to stream
-        let content = item_with_content.content;
+        // Convert content to stream with length limit
+        let mut content = item_with_content.content;
+        if length > 0 && length < content.len() as u64 {
+            content.truncate(length as usize);
+        }
         let stream = Box::pin(tokio_stream::iter(vec![Ok(tokio_util::bytes::Bytes::from(content))]));
         
         Ok((stream, mime_type))