The tolerance fix in r2 named the room's nearest polygon vertex as the point
of contact, which silently excluded the T-junction — a partition meeting the
middle of a room wall. That is a documented product case (141-wall-junctions
§13.1) and the code already measures distance to the edge, not the vertex
(distToSegment over roomEdges). Merging would have run straight through a
legitimate node.
AC2 now proves the room case with a T-junction into the middle of a long
side, and a mutant restores the vertex-only search.
Issue: #229
User-Visible: no
M1: "merge across the whole space when a chain ends" quietly overreached the
owner's split — drawing fixes its own seam, the optimiser fixes what has piled
up, and only the latter comes with a report and an undo. Section 8.6 now scopes
it to the connected component the new chain belongs to.
M2: the tolerance for "something else meets here" was only defined for a
partition-to-partition joint. Room edges, columns and drafts now use the same
EPS_JOIN — a gap cannot be a junction in one case and not in another.
M3: an opening also carries a materialised x/y/angle projection that
CONFIG-COMPATIBILITY (#132) requires to stay in step with its host, and the
code already re-materialises it after every host change. Merging is such a
change; AC3 now fails if only host.t is recomputed and the projection goes
stale.
Issue: #229
User-Visible: no
Written on the owner's decisions of 2026-08-21: merge as the chain is
finished, sweep already-drawn plans from "Optimise plans", and keep merging
even when an opening sits on the seam.
The part that is easy to miss is that last one. An opening stores its
position as a fraction of its host's length, so merging two partitions
changes the length under it and moves the door unless the fraction is
recomputed. AC3 therefore checks the door's coordinates in plan units, not
that a field was rewritten.
Issue: #229
User-Visible: no
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