Function handle_edit_insert_before 

pub async fn handle_edit_insert_before(
    name: &str,
    code: &str,
    client: &mut LspClient,
    file_tracker: &mut FileTracker,
    project_root: &Path,
    dirty_files: &DirtyFiles,
) -> Result<Value>

Insert code before a symbol, skipping any leading attributes/decorators/doc comments.

Scans upward from the symbol’s start line to find #[...], @decorator, or //////! doc comment lines, and inserts before those.

Errors

Returns an error if the symbol can’t be found or the file can’t be written.