KOS_OP_TAIL_CALL_VAR_ATTR

• Style: EXTRA. Schema: VAR (name for obj), CONST (attr name), COUNT (npos), NOARG. One cache slot.

• Stack: Same layout as CALL_VAR_ATTR: args only; obj is loaded from the frame namespace by name (owned deref, released on every path). Tail semantics as KOS_OP_TAIL_CALL_ATTR: the caller’s frame is reused rather than a new frame pushed.

• Compiler form: Promotion relabel of a tail-position CALL_VAR_ATTR; lowers to TAIL_CALL_FAST_ATTR.