FA-86791 / Procedural level generation constraints / Open access
Door placement between rooms: Door placed beyond the shared wall · case 01
Doors open into solid rock beside the smaller room.
ROOT CAUSE
The shared span ends at the larger room edge.
VERIFIED REPAIR
Restore `hi = min(py + ph, qy + qh)` at the shared span end step.
Unsuccessful approach: Extending the span by one tile allows a door at the corner.
Case contract
Rooms [x, y, w, h] are interiors separated by one wall tile when x_a + w_a + 1 == x_b (b right of a) or y_a + h_a + 1 == y_b (b below a), checked in both room orders. The door sits in the wall at the middle of the shared span [lo, hi) (lower middle for even spans): column x_a+w_a for side-by-side rooms, row y_a+h_a for stacked rooms. Returns [x, y] or None.
Why this case matters
Procedural generators silently emit unplayable or unfair levels when a single constraint check uses the wrong boundary, axis, neighborhood or update order; the defect is visible in exact generated geometry.
1 / The failure
Exit 1"""Failure Map reference implementation. Python standard library only."""
import json
N = 1
observations = []
def solve(a, b):
def door(p, q):
px, py, pw, ph = p
qx, qy, qw, qh = q
if px + pw + 1 == qx:
lo = max(py, qy)
hi = max(py + ph, qy + qh)
if hi - lo >= 1:
return [px + pw, lo + (hi - lo - 1) // 2]
if py + ph + 1 == qy:
lo = max(px, qx)
hi = min(px + pw, qx + qw)
if hi > lo:
return [(lo + hi - 1) // 2, py + ph]
return None
return door(a, b) or door(b, a)
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
cases = [[('side by side #1', [[0, 0, 3, 4], [4, 1, 2, 5]], [3, 2]),
('regression shared span end #1', [[13, 5, 1, 2], [6, 2, 6, 6]], [12, 5]),
('fault site shared span end #1', [[11, 7, 6, 3], [7, 7, 3, 1]], [10, 7]),
('regression shared span end #2', [[9, 4, 3, 2], [13, 6, 1, 5]], None),
('regression shared span end #3', [[8, 9, 3, 6], [5, 4, 2, 5]], None),
('stacked reversed order #1', [[2, 5, 3, 2], [1, 0, 4, 4]], [3, 4]),
('rooms touching without wall #1', [[0, 0, 3, 3], [3, 0, 3, 3]], None),
('control #1', [[6, 10, 4, 6], [5, 7, 4, 3]], None)],
[('side by side #1', [[0, 0, 3, 4], [4, 1, 2, 5]], [3, 2]),
('fault site shared span end #1', [[11, 7, 6, 3], [7, 7, 3, 1]], [10, 7]),
('fault site shared span end #2', [[7, 0, 5, 3], [2, 4, 4, 3]], None),
('regression shared span end #1', [[8, 9, 3, 6], [5, 4, 2, 5]], None),
('regression shared span end #2', [[10, -3, 6, 3], [4, 0, 5, 6]], None),
('stacked reversed order #1', [[2, 5, 3, 2], [1, 0, 4, 4]], [3, 4]),
('rooms touching without wall #1', [[0, 0, 3, 3], [3, 0, 3, 3]], None),
('control #1', [[6, 10, 4, 6], [5, 7, 4, 3]], None)],
[('side by side #1', [[0, 0, 3, 4], [4, 1, 2, 5]], [3, 2]),
('fault site shared span end #1', [[7, 1, 1, 5], [9, 7, 2, 4]], None),
('fault site shared span end #2', [[2, 7, 4, 4], [7, 5, 4, 1]], None),
('regression shared span end #1', [[11, 6, 3, 5], [4, 9, 6, 6]], [10, 9]),
('regression shared span end #2', [[11, 14, 1, 4], [6, 9, 4, 5]], None),
('stacked reversed order #1', [[2, 5, 3, 2], [1, 0, 4, 4]], [3, 4]),
('rooms touching without wall #1', [[0, 0, 3, 3], [3, 0, 3, 3]], None),
('control #1', [[6, 10, 4, 6], [5, 7, 4, 3]], None)],
[('side by side #1', [[0, 0, 3, 4], [4, 1, 2, 5]], [3, 2]),
('fault site shared span end #1', [[3, 11, 4, 2], [8, 8, 1, 2]], None),
('fault site shared span end #2', [[10, 9, 4, 1], [15, 9, 3, 4]], [14, 9]),
('regression shared span end #1', [[8, 1, 5, 5], [4, 6, 3, 1]], None),
('regression shared span end #2', [[10, 9, 4, 3], [7, 7, 2, 2]], None),
('stacked reversed order #1', [[2, 5, 3, 2], [1, 0, 4, 4]], [3, 4]),
('rooms touching without wall #1', [[0, 0, 3, 3], [3, 0, 3, 3]], None),
('control #1', [[3, 10, 2, 1], [6, 6, 6, 5]], [5, 10])],
[('side by side #1', [[0, 0, 3, 4], [4, 1, 2, 5]], [3, 2]),
('fault site shared span end #1', [[3, 5, 4, 5], [8, 0, 3, 2]], None),
('regression shared span end #1', [[9, 4, 3, 2], [13, 6, 1, 5]], None),
('regression shared span end #2', [[6, 7, 6, 6], [0, 13, 5, 3]], None),
('regression shared span end #3', [[10, 6, 6, 3], [5, 9, 4, 2]], None),
('stacked reversed order #1', [[2, 5, 3, 2], [1, 0, 4, 4]], [3, 4]),
('rooms touching without wall #1', [[0, 0, 3, 3], [3, 0, 3, 3]], None),
('control #1', [[0, 14, 4, 5], [3, 9, 3, 1]], None)]]
for label, args, expected in cases[N-1]:
check(label, solve(*args), expected)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)
| Boundary fixture | Actual | Expected | Outcome |
|---|---|---|---|
| side by side #1 | [3, 3] | [3, 2] | Failed |
| regression shared span end #1 | [12, 6] | [12, 5] | Failed |
| fault site shared span end #1 | [10, 8] | [10, 7] | Failed |
| regression shared span end #2 | [12, 8] | None | Failed |
| regression shared span end #3 | [7, 11] | None | Failed |
| stacked reversed order #1 | [3, 4] | [3, 4] | Passed |
| rooms touching without wall #1 | None | None | Passed |
| control #1 | None | None | Passed |
SHA-256 / 57e2ad23c624dfb7e5e5a28fc9d5093037cde9a54025af9b4016405f7b6b3170
2 / The unsuccessful fix
Exit 1"""Failure Map reference implementation. Python standard library only."""
import json
N = 1
observations = []
def solve(a, b):
def door(p, q):
px, py, pw, ph = p
qx, qy, qw, qh = q
if px + pw + 1 == qx:
lo = max(py, qy)
hi = min(py + ph, qy + qh) + 1
if hi - lo >= 1:
return [px + pw, lo + (hi - lo - 1) // 2]
if py + ph + 1 == qy:
lo = max(px, qx)
hi = min(px + pw, qx + qw)
if hi > lo:
return [(lo + hi - 1) // 2, py + ph]
return None
return door(a, b) or door(b, a)
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
cases = [[('side by side #1', [[0, 0, 3, 4], [4, 1, 2, 5]], [3, 2]),
('regression shared span end #1', [[13, 5, 1, 2], [6, 2, 6, 6]], [12, 5]),
('fault site shared span end #1', [[11, 7, 6, 3], [7, 7, 3, 1]], [10, 7]),
('regression shared span end #2', [[9, 4, 3, 2], [13, 6, 1, 5]], None),
('regression shared span end #3', [[8, 9, 3, 6], [5, 4, 2, 5]], None),
('stacked reversed order #1', [[2, 5, 3, 2], [1, 0, 4, 4]], [3, 4]),
('rooms touching without wall #1', [[0, 0, 3, 3], [3, 0, 3, 3]], None),
('control #1', [[6, 10, 4, 6], [5, 7, 4, 3]], None)],
[('side by side #1', [[0, 0, 3, 4], [4, 1, 2, 5]], [3, 2]),
('fault site shared span end #1', [[11, 7, 6, 3], [7, 7, 3, 1]], [10, 7]),
('fault site shared span end #2', [[7, 0, 5, 3], [2, 4, 4, 3]], None),
('regression shared span end #1', [[8, 9, 3, 6], [5, 4, 2, 5]], None),
('regression shared span end #2', [[10, -3, 6, 3], [4, 0, 5, 6]], None),
('stacked reversed order #1', [[2, 5, 3, 2], [1, 0, 4, 4]], [3, 4]),
('rooms touching without wall #1', [[0, 0, 3, 3], [3, 0, 3, 3]], None),
('control #1', [[6, 10, 4, 6], [5, 7, 4, 3]], None)],
[('side by side #1', [[0, 0, 3, 4], [4, 1, 2, 5]], [3, 2]),
('fault site shared span end #1', [[7, 1, 1, 5], [9, 7, 2, 4]], None),
('fault site shared span end #2', [[2, 7, 4, 4], [7, 5, 4, 1]], None),
('regression shared span end #1', [[11, 6, 3, 5], [4, 9, 6, 6]], [10, 9]),
('regression shared span end #2', [[11, 14, 1, 4], [6, 9, 4, 5]], None),
('stacked reversed order #1', [[2, 5, 3, 2], [1, 0, 4, 4]], [3, 4]),
('rooms touching without wall #1', [[0, 0, 3, 3], [3, 0, 3, 3]], None),
('control #1', [[6, 10, 4, 6], [5, 7, 4, 3]], None)],
[('side by side #1', [[0, 0, 3, 4], [4, 1, 2, 5]], [3, 2]),
('fault site shared span end #1', [[3, 11, 4, 2], [8, 8, 1, 2]], None),
('fault site shared span end #2', [[10, 9, 4, 1], [15, 9, 3, 4]], [14, 9]),
('regression shared span end #1', [[8, 1, 5, 5], [4, 6, 3, 1]], None),
('regression shared span end #2', [[10, 9, 4, 3], [7, 7, 2, 2]], None),
('stacked reversed order #1', [[2, 5, 3, 2], [1, 0, 4, 4]], [3, 4]),
('rooms touching without wall #1', [[0, 0, 3, 3], [3, 0, 3, 3]], None),
('control #1', [[3, 10, 2, 1], [6, 6, 6, 5]], [5, 10])],
[('side by side #1', [[0, 0, 3, 4], [4, 1, 2, 5]], [3, 2]),
('fault site shared span end #1', [[3, 5, 4, 5], [8, 0, 3, 2]], None),
('regression shared span end #1', [[9, 4, 3, 2], [13, 6, 1, 5]], None),
('regression shared span end #2', [[6, 7, 6, 6], [0, 13, 5, 3]], None),
('regression shared span end #3', [[10, 6, 6, 3], [5, 9, 4, 2]], None),
('stacked reversed order #1', [[2, 5, 3, 2], [1, 0, 4, 4]], [3, 4]),
('rooms touching without wall #1', [[0, 0, 3, 3], [3, 0, 3, 3]], None),
('control #1', [[0, 14, 4, 5], [3, 9, 3, 1]], None)]]
for label, args, expected in cases[N-1]:
check(label, solve(*args), expected)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)
| Boundary fixture | Actual | Expected | Outcome |
|---|---|---|---|
| side by side #1 | [3, 2] | [3, 2] | Passed |
| regression shared span end #1 | [12, 6] | [12, 5] | Failed |
| fault site shared span end #1 | [10, 7] | [10, 7] | Passed |
| regression shared span end #2 | [12, 6] | None | Failed |
| regression shared span end #3 | [7, 9] | None | Failed |
| stacked reversed order #1 | [3, 4] | [3, 4] | Passed |
| rooms touching without wall #1 | None | None | Passed |
| control #1 | None | None | Passed |
SHA-256 / 8ebe028500787ec7f62ae96dac270cd5f06a49b4fe186a2106e4d64fbcdae7e9
3 / The verified repair
Exit 0"""Failure Map reference implementation. Python standard library only."""
import json
N = 1
observations = []
def solve(a, b):
def door(p, q):
px, py, pw, ph = p
qx, qy, qw, qh = q
if px + pw + 1 == qx:
lo = max(py, qy)
hi = min(py + ph, qy + qh)
if hi - lo >= 1:
return [px + pw, lo + (hi - lo - 1) // 2]
if py + ph + 1 == qy:
lo = max(px, qx)
hi = min(px + pw, qx + qw)
if hi > lo:
return [(lo + hi - 1) // 2, py + ph]
return None
return door(a, b) or door(b, a)
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
cases = [[('side by side #1', [[0, 0, 3, 4], [4, 1, 2, 5]], [3, 2]),
('regression shared span end #1', [[13, 5, 1, 2], [6, 2, 6, 6]], [12, 5]),
('fault site shared span end #1', [[11, 7, 6, 3], [7, 7, 3, 1]], [10, 7]),
('regression shared span end #2', [[9, 4, 3, 2], [13, 6, 1, 5]], None),
('regression shared span end #3', [[8, 9, 3, 6], [5, 4, 2, 5]], None),
('stacked reversed order #1', [[2, 5, 3, 2], [1, 0, 4, 4]], [3, 4]),
('rooms touching without wall #1', [[0, 0, 3, 3], [3, 0, 3, 3]], None),
('control #1', [[6, 10, 4, 6], [5, 7, 4, 3]], None)],
[('side by side #1', [[0, 0, 3, 4], [4, 1, 2, 5]], [3, 2]),
('fault site shared span end #1', [[11, 7, 6, 3], [7, 7, 3, 1]], [10, 7]),
('fault site shared span end #2', [[7, 0, 5, 3], [2, 4, 4, 3]], None),
('regression shared span end #1', [[8, 9, 3, 6], [5, 4, 2, 5]], None),
('regression shared span end #2', [[10, -3, 6, 3], [4, 0, 5, 6]], None),
('stacked reversed order #1', [[2, 5, 3, 2], [1, 0, 4, 4]], [3, 4]),
('rooms touching without wall #1', [[0, 0, 3, 3], [3, 0, 3, 3]], None),
('control #1', [[6, 10, 4, 6], [5, 7, 4, 3]], None)],
[('side by side #1', [[0, 0, 3, 4], [4, 1, 2, 5]], [3, 2]),
('fault site shared span end #1', [[7, 1, 1, 5], [9, 7, 2, 4]], None),
('fault site shared span end #2', [[2, 7, 4, 4], [7, 5, 4, 1]], None),
('regression shared span end #1', [[11, 6, 3, 5], [4, 9, 6, 6]], [10, 9]),
('regression shared span end #2', [[11, 14, 1, 4], [6, 9, 4, 5]], None),
('stacked reversed order #1', [[2, 5, 3, 2], [1, 0, 4, 4]], [3, 4]),
('rooms touching without wall #1', [[0, 0, 3, 3], [3, 0, 3, 3]], None),
('control #1', [[6, 10, 4, 6], [5, 7, 4, 3]], None)],
[('side by side #1', [[0, 0, 3, 4], [4, 1, 2, 5]], [3, 2]),
('fault site shared span end #1', [[3, 11, 4, 2], [8, 8, 1, 2]], None),
('fault site shared span end #2', [[10, 9, 4, 1], [15, 9, 3, 4]], [14, 9]),
('regression shared span end #1', [[8, 1, 5, 5], [4, 6, 3, 1]], None),
('regression shared span end #2', [[10, 9, 4, 3], [7, 7, 2, 2]], None),
('stacked reversed order #1', [[2, 5, 3, 2], [1, 0, 4, 4]], [3, 4]),
('rooms touching without wall #1', [[0, 0, 3, 3], [3, 0, 3, 3]], None),
('control #1', [[3, 10, 2, 1], [6, 6, 6, 5]], [5, 10])],
[('side by side #1', [[0, 0, 3, 4], [4, 1, 2, 5]], [3, 2]),
('fault site shared span end #1', [[3, 5, 4, 5], [8, 0, 3, 2]], None),
('regression shared span end #1', [[9, 4, 3, 2], [13, 6, 1, 5]], None),
('regression shared span end #2', [[6, 7, 6, 6], [0, 13, 5, 3]], None),
('regression shared span end #3', [[10, 6, 6, 3], [5, 9, 4, 2]], None),
('stacked reversed order #1', [[2, 5, 3, 2], [1, 0, 4, 4]], [3, 4]),
('rooms touching without wall #1', [[0, 0, 3, 3], [3, 0, 3, 3]], None),
('control #1', [[0, 14, 4, 5], [3, 9, 3, 1]], None)]]
for label, args, expected in cases[N-1]:
check(label, solve(*args), expected)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)
| Boundary fixture | Actual | Expected | Outcome |
|---|---|---|---|
| side by side #1 | [3, 2] | [3, 2] | Passed |
| regression shared span end #1 | [12, 5] | [12, 5] | Passed |
| fault site shared span end #1 | [10, 7] | [10, 7] | Passed |
| regression shared span end #2 | None | None | Passed |
| regression shared span end #3 | None | None | Passed |
| stacked reversed order #1 | [3, 4] | [3, 4] | Passed |
| rooms touching without wall #1 | None | None | Passed |
| control #1 | None | None | Passed |
SHA-256 / 0bbc31ec30d6efd0e00f1d44c4bb89d2b20576d4896324ac736e78e15de4bb41
Verification & scope
Deterministic toy contract stipulated for this model; integer or exact arithmetic only, not a reproduction of any specific game engine. This reproducer isolates one failure mechanism. Results cover the supplied fixtures. Variants within a family share a test contract and should remain grouped when constructing evaluation splits. Related mechanisms with a shared evaluation_group must also remain together; these controlled models are not independent production incidents.
Observations recorded using Python 3.12.14 at 2026-09-29T14:50:52.803224+00:00.
Case digest / ae7f0db4b21d58bfe5a05e4ff66e5ac438ca0307b1a5558ae3a3d94c056669d4