docs: Add comprehensive rustdoc to item_service.rs

Co-authored-by: aider (openai/andrew/openrouter/sonoma-sky-alpha) <aider@aider.chat>

src/services/item_service.rs

@@ -406,6 +406,36 @@ impl ItemService {
         Ok(item_id)
     }
 
+    /// Saves pre-loaded content as a new item, typically from MCP (Machine-Common-Processing) sources.
+    ///
+    /// Bypasses streaming read, directly writes content and applies metadata/plugins.
+    ///
+    /// # Arguments
+    ///
+    /// * `content` - Byte slice of content to save.
+    /// * `tags` - Tags to associate.
+    /// * `metadata` - Initial metadata key-value pairs.
+    /// * `cmd` - Mutable command.
+    /// * `settings` - Settings.
+    /// * `conn` - Mutable database connection.
+    ///
+    /// # Returns
+    ///
+    /// * `Result<ItemWithMeta, CoreError>` - The saved item with full details.
+    ///
+    /// # Errors
+    ///
+    /// * `CoreError::Database(...)` - If DB insert fails.
+    /// * `CoreError::Io(...)` - If file write fails.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// let content = b"Hello, world!";
+    /// let tags = vec!["mcp".to_string()];
+    /// let meta = HashMap::from([("source".to_string(), "api".to_string())]);
+    /// let item = service.save_item_from_mcp(content, &tags, &meta, &mut cmd, &settings, &mut conn)?;
+    /// ```
     pub fn save_item_from_mcp(
         &self,
         content: &[u8],
@@ -465,10 +495,20 @@ impl ItemService {
         self.get_item(conn, item_id)
     }
 
+    /// Returns a reference to the internal compression service.
+    ///
+    /// # Returns
+    ///
+    /// Reference to `CompressionService`.
     pub fn get_compression_service(&self) -> &CompressionService {
         &self.compression_service
     }
 
+    /// Returns a reference to the data directory path.
+    ///
+    /// # Returns
+    ///
+    /// Reference to `PathBuf`.
     pub fn get_data_path(&self) -> &PathBuf {
         &self.data_path
     }