Build your own house: walls, windows, doors, floors, roof, stairs, furniture

House parts (stdlib isokit/house): house_wall drawn along a line, with ends
that adapt at corners, T-junctions and straight runs so no two walls
overlap; window and door that sit on a wall and cut its opening (door
styles panel, glass, double, sliding, opening; swing and hinge by
rotation); floor (boards, tiles, carpet, stone); roof (hip, gable, flat,
optional solar); stairs.

Furniture (stdlib isokit/furniture): chair, sofa / armchair, table with
chairs, desk with monitor and chair, TV, bed, cupboard, bookshelf, kitchen
run, bathtub, shower, toilet, washbasin, plant, rug, floor lamp.

Cut-open levels: on gf / 1f the walls in front of a room are cut low
(rooms are found by their floors), the roof becomes an outline on the
floor, and storeys above are left out. A part's storey comes from z
(storey_h, default 3 m).

Scripting: objects_of, objects_at, objects_on, mount_of, mounted, frame,
to_world, to_local, local_of. Prefab meta: shape (line / rect), mount,
storey.

Studio: drag to draw lines and rectangles (walls, roads, fences, hedges,
floors, areas, buildings, roofs). The Room tool draws a floor plus walls,
without doubling walls that already stand on an edge. Windows and doors
snap onto walls with a hover preview, and they move, turn, copy and
delete with their wall in one undo step. New parts land on the storey
the view shows. Palette categories collapse, and the palette scrolls
apart from the object list.

The MCP instructions explain house building, and list_prefabs shows
sits_on. examples/house is a furnished bungalow; the web Studio gets a
House demo button. Tests: wall corners and junctions, zero depth-sort
cycles in every view, cut levels, and the house demo in every view;
check_studio covers the room / window / door / storey flow, check_web
the House demo.

docs/ROADMAP.md

@@ -49,10 +49,41 @@ Each phase ends with tests, a Studio/viewer check in Edge, commit and push.
 - [ ] Keep the conversation per project across reloads; attach a rendered view (PNG, Phase 4)
       for vision models
 
+## Build your own house (done)
+
+- [x] House parts: `house_wall` (drawn along a line, ends adapt at corners, T-junctions and
+      straight runs), `window` and `door` that sit on a wall and cut its opening (door styles:
+      panel, glass, double, sliding, opening; open / closed, hinge and swing by rotation),
+      `floor` (boards / tiles / carpet / stone), `roof` (hip, gable, flat, solar), `stairs`
+- [x] Furniture: chair, sofa / armchair, table with chairs, desk with monitor and chair, TV,
+      bed with nightstands, cupboard, bookshelf, kitchen run (sink, hob, wall cabinets, fridge),
+      bathtub, shower, toilet, washbasin, plant, rug, floor lamp
+- [x] Cut-open levels for houses: walls in front of rooms cut low (rooms found by their floors),
+      roof as an outline, storeys from z (`storey_h`), upper storeys left out
+- [x] Scripting: `objects_of`, `objects_at`, `objects_on`, `mount_of`, `mounted`, `frame`,
+      `to_world`, `to_local`, `local_of`; prefab meta `shape` (line / rect), `mount`, `storey`
+- [x] Studio: drag to draw lines and rectangles (walls, roads, fences, floors, areas, buildings),
+      Room tool (floor + walls, shared walls not doubled), windows and doors snap onto walls
+      (hover preview) and move, turn, copy and delete with them, new parts land on the storey
+      shown, collapsible palette that scrolls on its own
+- [x] `examples/house` (a furnished house built from parts), House demo in the web Studio
+- [ ] Openings across two walls; diagonal walls; floor openings for stairs
+
+## Backlog (2026-10)
+
+1. Web performance: the web build runs smoothly on low-power machines
+2. Conveyors: placeable conveyors
+3. Producers with adjustable production speed
+4. Robotic arms
+5. Rounded streets: curved road segments
+6. Sidewalks along streets
+7. Roundabouts
+8. Waypoint animation: a person or car moving along a path of waypoints
+9. ~~Build your own house~~ (done, see above)
+
 ## Phase 2: richer editing
 
-- [ ] Interior prefabs (desk, table with chairs, shelf, machine, bed, sofa, partition walls) and a
-      building `rooms` prop, so the GF/1F levels show something
+- [x] Interior prefabs (see Build your own house); a building `rooms` prop is still open
 - [ ] Path objects in the Studio: click points for areas, roads (polyline with width), fences, walls,
       pipe runs; vertex handles
 - [ ] Multi-select (box select, Shift-click), group move, align/distribute