Both upgrades sit behind an opt-in shove=False flag, so the default code
path is byte-for-byte the foundation router (existing room tests are
unchanged by construction).
With shove=True:
- Gate placement becomes occupancy-aware: each edge gate is projected
into the largest other-net-free sub-span of the door, with the reserved
intervals read straight from the search tree. With margin = clearance +
half_width the room decomposition already keeps doors clearance-clear,
so this reduces exactly to the old midpoint clamp where no other-net
copper crosses the door.
- When a net would be dropped, a transactional shove-in-rooms recovery
nudges the committed trace(s) blocking it aside with the exact shove
primitive and re-verifies against the clearance oracle, so both nets fit
through one channel. Every moved trace is journaled and rolled back to
its exact original tiles and wires on any failure -- the room engine
mutates already-committed nets, so the rollback is real rather than the
exact track's no-op.
The board-wide has_violation(clearance) gate stays the final assertion.
Thread the flag through pipeline.route_dsn_board_rooms /
build_rooms_routing_result / route(engine='room', shove=...).
A third engine (engine='room') that replaces the fixed routing grid with
FreeRouting's free-space rooms. Per layer, the space not occupied by items
(inflated by the routing clearance) is decomposed into exact rectangles via
coordinate compression (the orthogonal analogue of
CompleteFreeSpaceExpansionRoom); adjacent rooms share an edge door, and a via
door joins overlapping rooms on two layers. The maze search is an A* over
rooms-through-doors (cost = geometric distance + via cost), so a path may
cross a door anywhere along its width rather than at a quantized cell. The
found room sequence is realized into an exact orthogonal Polyline through the
door mid-gates and verified DRC-clean against the ShapeSearchTree, dropping
the net if it cannot be made exactly clean.
Maps to autoroute/: ExpansionRoom / CompleteFreeSpaceExpansionRoom (rooms),
ExpansionDoor / TargetItemExpansionDoor (doors), MazeSearchAlgo /
AutorouteEngine (search), LocateFoundConnectionAlgo (realization).
Foundation scope: rooms are axis-aligned rectangles (not general Simplex
tiles); realization uses an L-connector through door mid-gates. Any-angle
rooms, optimal gate placement (true sub-cell shove), and optimization passes
are follow-ups. The grid and exact tracks are unchanged; this is opt-in.
Routes simple/crossing (with a via) and all four multi-pin nets of the real
KiCad board, DRC-clean.
rsp2k