feat: optimize item content streaming to reduce redundant database calls

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

src/modes/server/api/item.rs

@@ -232,7 +232,7 @@ async fn stream_item_content_response(
     offset: u64,
     length: u64,
 ) -> Result<Response, StatusCode> {
-    // First get the item metadata to check if it's binary and get MIME type
+    // Get the item with metadata once
     let item_with_meta = item_service.get_item(item_id).await.map_err(|e| {
         warn!("Failed to get item {} for content: {}", item_id, e);
         StatusCode::INTERNAL_SERVER_ERROR
@@ -246,21 +246,26 @@ async fn stream_item_content_response(
     
     // Check if content is binary when allow_binary is false
     if !allow_binary {
+        let is_binary = if let Some(binary_val) = metadata.get("binary") {
+            binary_val == "true"
+        } else {
+            // If binary metadata isn't set, we need to check the content
             match item_service.get_item_content_info(item_id).await {
-            Ok((_, _, is_binary)) => {
-                if is_binary {
-                    return Err(StatusCode::BAD_REQUEST);
-                }
-            }
+                Ok((_, _, is_binary)) => is_binary,
                 Err(e) => {
                     warn!("Failed to get content info for binary check for item {}: {}", item_id, e);
                     return Err(StatusCode::INTERNAL_SERVER_ERROR);
                 }
             }
+        };
+        
+        if is_binary {
+            return Err(StatusCode::BAD_REQUEST);
+        }
     }
     
-    // Now stream the content with the specified offset and length
-    match item_service.stream_item_content_by_id(item_id, true, offset, length).await {
+    // Now stream the content with the specified offset and length using pre-fetched metadata
+    match item_service.stream_item_content_by_id_with_metadata(item_id, &metadata, true, offset, length).await {
         Ok((stream, _)) => {
             let body = axum::body::Body::from_stream(stream);
             let response = Response::builder()

src/services/async_item_service.rs

@@ -70,14 +70,99 @@ impl AsyncItemService {
         let db = self.db.clone();
         let item_service = self.item_service.clone();
 
-        // Get item content, mime type, and binary status
-        let (content, mime_type, is_binary) = tokio::task::spawn_blocking(move || {
+        // Get item content
+        let content = tokio::task::spawn_blocking(move || {
             let conn = db.blocking_lock();
-            item_service.get_item_content_info(&conn, item_id)
+            let item_with_content = item_service.get_item_content(&conn, item_id)?;
+            Ok::<_, CoreError>(item_with_content.content)
         })
         .await
         .unwrap()?;
         
+        // Get metadata to determine MIME type and binary status
+        let (mime_type, is_binary) = {
+            let db = self.db.clone();
+            let item_service = self.item_service.clone();
+            tokio::task::spawn_blocking(move || {
+                let conn = db.blocking_lock();
+                let item_with_meta = item_service.get_item(&conn, item_id)?;
+                let metadata = item_with_meta.meta_as_map();
+                
+                let mime_type = metadata
+                    .get("mime_type")
+                    .map(|s| s.to_string())
+                    .unwrap_or_else(|| "application/octet-stream".to_string());
+                
+                let is_binary = if let Some(binary_val) = metadata.get("binary") {
+                    binary_val == "true"
+                } else {
+                    crate::common::is_binary::is_binary(&content)
+                };
+                
+                Ok::<_, CoreError>((mime_type, is_binary))
+            })
+            .await
+            .unwrap()?
+        };
+        
+        // Check if content is binary when allow_binary is false
+        if !allow_binary && is_binary {
+            return Err(CoreError::InvalidInput("Binary content not allowed".to_string()));
+        }
+        
+        // Create a stream that reads only the requested portion
+        let content_len = content.len() as u64;
+        
+        // Apply offset and length constraints
+        let start = std::cmp::min(offset, content_len);
+        let end = if length > 0 {
+            std::cmp::min(start + length, content_len)
+        } else {
+            content_len
+        };
+        
+        let stream = if start < content_len {
+            let chunk = tokio_util::bytes::Bytes::from(content[start as usize..end as usize].to_vec());
+            Box::pin(tokio_stream::iter(vec![Ok(chunk)]))
+        } else {
+            Box::pin(tokio_stream::iter(vec![]))
+        };
+        
+        Ok((stream, mime_type))
+    }
+
+    pub async fn stream_item_content_by_id_with_metadata(
+        &self,
+        item_id: i64,
+        metadata: &HashMap<String, String>,
+        allow_binary: bool,
+        offset: u64,
+        length: u64,
+    ) -> Result<(std::pin::Pin<Box<dyn tokio_stream::Stream<Item = Result<tokio_util::bytes::Bytes, std::io::Error>> + Send>>, String), CoreError> {
+        let db = self.db.clone();
+        let item_service = self.item_service.clone();
+
+        // Get item content
+        let content = tokio::task::spawn_blocking(move || {
+            let conn = db.blocking_lock();
+            let item_with_content = item_service.get_item_content(&conn, item_id)?;
+            Ok::<_, CoreError>(item_with_content.content)
+        })
+        .await
+        .unwrap()?;
+        
+        // Use provided metadata to determine MIME type and binary status
+        let mime_type = metadata
+            .get("mime_type")
+            .map(|s| s.to_string())
+            .unwrap_or_else(|| "application/octet-stream".to_string());
+        
+        let is_binary = if let Some(binary_val) = metadata.get("binary") {
+            binary_val == "true"
+        } else {
+            crate::common::is_binary::is_binary(&content)
+        };
+        
         // Check if content is binary when allow_binary is false
         if !allow_binary && is_binary {
             return Err(CoreError::InvalidInput("Binary content not allowed".to_string()));