A leadless biostimulator including an attachment feature to facilitate precise manipulation during delivery or retrieval is described. The attachment feature can be monolithically formed from a rigid material, and includes a base, a button, and a stem interconnecting the base to the button. The stem is a single post having a transverse profile extending around a central axis. The transverse profile can be annular and can surround the central axis. The leadless biostimulator includes a battery assembly having a cell can that includes an end boss. A tether recess in the end boss is axially aligned with a face port in the button to receive tethers of a delivery or retrieval system through an inner lumen of the stem. The attachment feature can be mounted on and welded to the cell can at a thickened transition region around the end boss. Other embodiments are also described and claimed.