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Find spaces you cannot reach

Sweep out the rooms nobody can get into, then write the openings that connect them.

check does not ask this question. check looks at whether what is written contradicts itself as data, not at whether the building works. A building with no doors at all is completely sealed and completely green. koyu validate and koyu doors are what catch it — run them beside check on every edit.

File paths in the output below are absolute when you actually run these commands. They are shortened to bare filenames here for readability.

Why buildings seal themselves​

Between two spaces that touch, and about which nothing has been declared, a wall with no door is derived. That is the default, and a default wall is not passable. Adding a room is, by itself, connecting it to nothing.

1. Sweep the whole model — validate​

validate lists every room that cannot reach the exterior. You do not have to nominate a starting point.

koyu 1.0
name A sealed house
unit mm

grid X 0 3600 5400
grid Y 0 4000
level L1 0 h:2400 slab:500
level L2 2900 h:2400 slab:500
level R 5800 slab:500

space /out exterior name:Outside

space /L1/ldk  ldk     X1..X2 Y1..Y2 name:LDK
space /L1/hall hall    X2..X3 Y1..Y2 name:Entry
space /L2/bed  bedroom X1..X2 Y1..Y2 name:Bedroom
space /L2/hall hall    X2..X3 Y1..Y2 name:Upper-hall

boundary /L1/hall /out edge:E t:150 spec:EW
  door w:900 name:Front-door
boundary /L1/ldk /out edge:W t:150 spec:EW
boundary /L2/bed /out edge:W t:150 spec:EW
boundary /L2/hall /out edge:E t:150 spec:EW

boundary /L1/hall /L2/hall type:stair
$ npx tsx src/cli.ts check house.muro
✔ Consistent — 5 spaces / 7 boundaries
  Structural consistency only — architectural validity is what koyu validate says, separately

Five boundaries written, seven reported: the other two are default walls between rooms that touch. check is green.

$ npx tsx src/cli.ts validate house.muro
⚠ [envelope.gap] house.muro:line 13: Perimeter not faced by any envelope: /L1/ldk — S 3600mm / N 3600mm (7200mm over 2 run(s)). Write a boundary to the exterior
⚠ [envelope.gap] house.muro:line 14: Perimeter not faced by any envelope: /L1/hall — S 1800mm / N 1800mm (3600mm over 2 run(s)). Write a boundary to the exterior
⚠ [envelope.gap] house.muro:line 15: Perimeter not faced by any envelope: /L2/bed — S 3600mm / N 3600mm (7200mm over 2 run(s)). Write a boundary to the exterior
⚠ [envelope.gap] house.muro:line 16: Perimeter not faced by any envelope: /L2/hall — S 1800mm / N 1800mm (3600mm over 2 run(s)). Write a boundary to the exterior
✖ [access.unreachable] house.muro:line 13: Cannot reach the exterior: /L1/ldk (no passable boundary leads out — write a door)
✖ [access.unreachable] house.muro:line 15: Cannot reach the exterior: /L2/bed (no passable boundary leads out — write a door)
Validation — 2 violations / 4 cautions

access.unreachable is the violation, and it is the trap. validate exits 1 only when there are violations — that single command is enough to defend escape routes in CI. As a bonus, envelope.gap reports perimeter that faces nothing at all. The full list of rules is the validation reference.

2. Count one route — doors​

To count between a specific pair, use doors. It prints the fewest doors and the route.

$ npx tsx src/cli.ts doors house.muro /L2/bed /out
Cannot reach /out from /L2/bed

Exit code 1. You cannot get out of the bedroom of a green building.

3. See which edges are walls — graph​

koyu graph lists each space's neighbours with the kind of boundary between them.

$ npx tsx src/cli.ts graph house.muro
/out (Outside)
  — 1 door → /L1/hall  (spec:EW)
  | wall → /L1/ldk  (spec:EW)
  | wall → /L2/bed  (spec:EW)
  | wall → /L2/hall  (spec:EW)
/L1/ldk (LDK)
  | wall → /out  (spec:EW)
  | wall → /L1/hall
/L1/hall (Entry)
  — 1 door → /out  (spec:EW)
  ↕ stair → /L2/hall
  | wall → /L1/ldk
/L2/bed (Bedroom)
  | wall → /out  (spec:EW)
  | wall → /L2/hall
/L2/hall (Upper-hall)
  | wall → /out  (spec:EW)
  ↕ stair → /L1/hall
  | wall → /L2/bed

| wall is a wall with no door in it, and nobody passes. A | wall line with no spec: is a default wall — derived, never written. Those are /L1/ldk ↔ /L1/hall and /L2/bed ↔ /L2/hall: no way out of the bedroom, no way out of the living room.

4. Write a door on the boundary that blocks​

To put a door into a default wall, declare that pair's boundary and indent a door under it. Declaring it stops the default from being derived; what you wrote is now the boundary for that pair.

boundary /L1/ldk /L1/hall t:120 spec:LGS
  door w:800
boundary /L2/bed /L2/hall t:120 spec:LGS
  door w:800
$ npx tsx src/cli.ts doors house.muro /L2/bed /out
2 doors — /L2/bed → /L2/hall → /L1/hall → /out

$ npx tsx src/cli.ts validate house.muro
Validation — 0 violations / 4 cautions

The violations are gone. The four remaining cautions are gaps in the envelope.

Which boundaries are edges​

The graph that doors and access.unreachable walk is decided by the boundary type alone.

BoundaryPassableDoors counted
wall (default, no door)no—
wall with a dooryes1
openalways0
stair (vertical)always0
shaft (vertical)no—
void (vertical)no—

air:1 is about enclosure, not about passage. Balustrades, railings and boundary walls let air through and people not. Write a door if people should pass.

$ npx tsx src/cli.ts doors examples/house.muro /home/void /home/hall2
Cannot reach /home/hall2 from /home/void

A shaft is continuous and still not a route.

$ npx tsx src/cli.ts doors examples/tower/main.muro /L1/ev /L2/ev
Cannot reach /L2/ev from /L1/ev

Three reasons for "cannot reach"​

  1. A doorless wall on the route — including a default wall. By far the most common.
  2. The route passes through a shaft or a void. A lift shaft that runs the full height of the building is not a route.
  3. The start or the end path does not exist. A misspelling produces the same message, so check the paths with graph first.

Doors that open where there is no floor​

There is one way to have a door and still not pass: a door that opens only onto a void. There is no floor, so nobody crosses.

✖ [access.unreachable] voidonly.muro:line 14: Cannot reach the exterior: /L2/bed (no passable boundary leads out — write a door)
✖ [access.voidonly] voidonly.muro:line 14: Doors open only onto a void: /L2/bed (they open where there is no floor, so nobody can pass)

The same thing happens outdoors. Give a balcony only a window and nobody can step onto it. An opening is either passage (door) or daylight (window); one opening cannot claim both. A full-height sliding assembly is written as a door for the sliding leaves and a window for the fixed panes.

Cars that cannot get out​

Car parks have their own test, separate from the pedestrian one. access.parking is a violation when a car park has no opening at least 2400mm wide, no type:open boundary and no ramp. A basement car park served only by a person-sized door is caught here.

✖ [access.parking] main.muro:line 32: No vehicle route to the exterior: /B2/park (needs an opening at least 2400mm wide, a type:open boundary, or a ramp)
✖ [access.parking] main.muro:line 32: No vehicle route to the exterior: /B1/park (needs an opening at least 2400mm wide, a type:open boundary, or a ramp)
✖ [access.parking] main.muro:line 33: No vehicle route to the exterior: /B2/ramp (needs an opening at least 2400mm wide, a type:open boundary, or a ramp)

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