KOS_OP_BUILD_LIST_EXTEND

• Style: NOARG.

• Stack: [..., list, iterable] → [..., list]. Extend the list in place from the TOS iterable (PySequence_InPlaceConcat, so any iterable the list API accepts); pop the iterable; leave the list. TypeError when the list slot is not a list.

• Compiler form: compile/#list *: splat segment.