A multi-line ATTRIB keeps its content in an embedded MTEXT; dxf.text is only
the first line (ezdxf) or "Line1\PLine2" (AutoCAD), so the TEXT the explode
emitted silently dropped lines or rendered literal \P with a clean audit.
ezdxf: `_burst_attrib` adds `virtual_mtext_entity()` (graphic properties and
WCS placement already carried; the reference matrix applied for a constant
ATTDEF) and marks it invisible like the ATTRIB. COM: `_capture_attrib` reads
`MTextAttribute` / `MTextAttributeContent` / `MTextBoundaryWidth` and
`_add_mtext_from_capture` goes through `AddMText` (height, style, frame,
then Rotation, then the attachment mapped from the ATTRIB's Alignment).
Two INSERT kinds `virtual_entities()` cannot explode were destroyed with
ok: True: an xref (no virtual entities, reference deleted) and a MINSERT
(only the first cell resolved, the rest of the grid gone). Both are now
refused by name before any write, on both engines (`block_record.is_xref`
/ `mcount > 1` headless; `Blocks.Item(Name).IsXRef` / `AcDbMInsertBlock`
live, the latter previously failing the INSERT check with the misleading
"not a block reference").
Tests: nine new cases in tests/test_track_a_hardening.py (headless multi-line
ATTRIB and constant ATTDEF, xref and MINSERT refusals, a single-cell grid
that still explodes; COM multi-line capture, frame-before-angle, and both
named refusals). The fake ActiveX surface gains AddMText and IsXRef.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01FKFStjEFzpGyLq5bMpWxTd
