The polyline was only committed to the document on finish, so its partial
geometry produced no snap points — you could not snap to vertices already
placed. Publish it as a real LwPolyline at the second vertex and replace
its geometry in place as later vertices land, so it lives in the document
(and the snapper) throughout the draw.
New CmdResult::CommitLiveEntity / UpdateLiveEntity{finish} plus a
set_live_handle() hook let a command own an entity mid-run. The create
pushes a single undo snapshot; in-place updates push none, so the whole
object reverts as one unit. Updates preserve the entity's handle and
layer (a fresh built entity carries a NULL handle that would desync it
from the document map key and drop it from rendering). (#119)
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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