Chair frame without seat.
Front corners are high-stress points that crack. This one has already been welded back together (welded from the back, so the weld isn’t very visible.)
The plastic is scored with a knife to make a rougher surface so the glue might hold better.
Next step: Reinforce the weak spot using some fiberglass window screen soaked in epoxy. Or maybe epoxy-polyurethane mix. Something mostly rigid, but not so hard that it cracks when flexed slightly, hopefully.
Two months later, the crack hasn’t spread. Cosmetically, the crack is visible. Structurally, the repair seems good enough.