pub type ToolPartialCb = extern "C" fn(partial: StbString, user_data: *mut c_void);Expand description
Partial-result callback the blocking driver passes to poll, wrapped in
catch_unwind on the host side. The plugin invokes it synchronously
inside poll() when it has a Pending partial — never retained, never
invoked after Done/Err.
partial is a JSON AgentToolResult; ownership passes to the callback (the
host frees it via the host’s free_string).