An unnamed UCS (UCS Origin / 3P without saving, the common kind) has an
empty UCSNAME exactly like WCS does, so both engines answered
`current: world` while the drawing was not in WCS — verified live on
AutoCAD 2026 (`_.UCS _O 10,10,0` → UCSNAME="" WORLDUCS=0) and on the DXF
it writes ($UCSNAME='' $UCSORG=(0,20,0)). A silent wrong value.
- COM: a named match still wins; otherwise WORLDUCS (AutoCAD's own answer)
decides, and WORLDUCS=0 appends a `name: None` row built from
UCSORG/UCSXDIR/UCSYDIR.
- ezdxf: the same rule against $UCSORG/$UCSXDIR/$UCSYDIR via the new
`engineering.environment.ucs.is_world_axes`; a stale $UCSNAME falls back
to the frame instead of leaving no row current.
- Server `ucs_list` result: `current` is null for an unnamed UCS (never
`world`), plus `current_unnamed: bool` so null is unambiguous.
- Tests: helper, headless (unnamed row, stale name, and the exact AutoCAD
DXF over the wire), and COM fake reading WORLDUCS + the frame variables.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01FKFStjEFzpGyLq5bMpWxTd
