FAILURE MAP
← Case archive

FA-86676 / Procedural level generation constraints / Open access

Wall autotile bitmask: Doors and chasms connect walls · case 01

Walls visually merge into doorways.

Verified by executionVariant 1 · 8 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

Any non-floor neighbour sets the bit.

VERIFIED REPAIR

Restore `if grid[rr][cc] == '#':` at the neighbour wall test step.

Unsuccessful approach: Doors still count as connecting walls.

Case contract

For each '#' cell the mask sums N=1, E=2, S=4, W=8 for 4-neighbours that are '#' (row 0 is north). Out-of-bounds neighbours count as walls when same_oob. Non-wall cells get -1. Returns rows of integers.

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(grid, same_oob):
    h = len(grid)
    w = len(grid[0])
    out = []
    for r in range(h):
        row = []
        for c in range(w):
            if grid[r][c] != '#':
                row.append(-1)
                continue
            m = 0
            for bit, (dr, dc) in ((1, (-1, 0)), (2, (0, 1)), (4, (1, 0)), (8, (0, -1))):
                rr, cc = r + dr, c + dc
                if 0 <= rr < h and 0 <= cc < w:
                    if grid[rr][cc] != '.':
                        m |= bit
                elif same_oob:
                    m |= bit
            row.append(m)
        out.append(row)
    return out
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
cases = [[('door next to wall #1', [['#D'], False], [[0, -1]]),
  ('regression neighbour wall test #1', [['.#D', '#.~'], True], [[-1, 1, -1], [12, -1, -1]]),
  ('regression neighbour wall test #2',
   [['~###', '##~.', 'D~~.', '#D#.', '#..#'], True],
   [[-1, 7, 11, 11], [10, 9, -1, -1], [-1, -1, -1, -1], [12, -1, 0, -1], [13, -1, -1, 6]]),
  ('regression neighbour wall test #3',
   [['##D', '..#', '##D'], True],
   [[11, 9, -1], [-1, -1, 2], [14, 12, -1]]),
  ('regression neighbour wall test #4', [['####D'], False], [[2, 10, 10, 8, -1]]),
  ('vertical wall pair #1', [['#', '#'], False], [[4], [1]]),
  ('lone wall at edge #1', [['#'], True], [[15]]),
  ('control #1', [['~', '~'], True], [[-1], [-1]])],
 [('door next to wall #1', [['#D'], False], [[0, -1]]),
  ('regression neighbour wall test #1',
   [['~###', '##~.', 'D~~.', '#D#.', '#..#'], True],
   [[-1, 7, 11, 11], [10, 9, -1, -1], [-1, -1, -1, -1], [12, -1, 0, -1], [13, -1, -1, 6]]),
  ('regression neighbour wall test #2',
   [['##D', '..#', '##D'], True],
   [[11, 9, -1], [-1, -1, 2], [14, 12, -1]]),
  ('regression neighbour wall test #3', [['####D'], False], [[2, 10, 10, 8, -1]]),
  ('regression neighbour wall test #4', [['D~#', '#~.'], False], [[-1, -1, 0], [0, -1, -1]]),
  ('vertical wall pair #1', [['#', '#'], False], [[4], [1]]),
  ('lone wall at edge #1', [['#'], True], [[15]]),
  ('control #1', [['~', '~'], True], [[-1], [-1]])],
 [('door next to wall #1', [['#D'], False], [[0, -1]]),
  ('regression neighbour wall test #1', [['####D'], False], [[2, 10, 10, 8, -1]]),
  ('regression neighbour wall test #2', [['D~#', '#~.'], False], [[-1, -1, 0], [0, -1, -1]]),
  ('regression neighbour wall test #3',
   [['##.D', '.D#~', '##..', '#.#~', '~D.#'], True],
   [[11, 9, -1, -1], [-1, -1, 0, -1], [14, 8, -1, -1], [9, -1, 0, -1], [-1, -1, -1, 6]]),
  ('regression neighbour wall test #4',
   [['#..D.', '.##.#', '..##D', 'D.#.D'], False],
   [[0, -1, -1, -1, -1], [-1, 2, 12, -1, 0], [-1, -1, 7, 8, -1], [-1, -1, 1, -1, -1]]),
  ('vertical wall pair #1', [['#', '#'], False], [[4], [1]]),
  ('lone wall at edge #1', [['#'], True], [[15]]),
  ('control #1', [['~', '~'], True], [[-1], [-1]])],
 [('door next to wall #1', [['#D'], False], [[0, -1]]),
  ('regression neighbour wall test #1',
   [['##.D', '.D#~', '##..', '#.#~', '~D.#'], True],
   [[11, 9, -1, -1], [-1, -1, 0, -1], [14, 8, -1, -1], [9, -1, 0, -1], [-1, -1, -1, 6]]),
  ('regression neighbour wall test #2',
   [['#..D.', '.##.#', '..##D', 'D.#.D'], False],
   [[0, -1, -1, -1, -1], [-1, 2, 12, -1, 0], [-1, -1, 7, 8, -1], [-1, -1, 1, -1, -1]]),
  ('regression neighbour wall test #3', [['~.#', '##D'], True], [[-1, -1, 3], [14, 12, -1]]),
  ('regression neighbour wall test #4',
   [['~D.D#', '#~.#D'], True],
   [[-1, -1, -1, -1, 3], [12, -1, -1, 4, -1]]),
  ('vertical wall pair #1', [['#', '#'], False], [[4], [1]]),
  ('lone wall at edge #1', [['#'], True], [[15]]),
  ('control #1', [['#', '#', '#'], False], [[4], [5], [1]])],
 [('door next to wall #1', [['#D'], False], [[0, -1]]),
  ('fault site neighbour wall test #1', [['~#', '.~', '.#'], True], [[-1, 3], [-1, -1], [-1, 6]]),
  ('regression neighbour wall test #1', [['~.#', '##D'], True], [[-1, -1, 3], [14, 12, -1]]),
  ('regression neighbour wall test #2',
   [['~D.D#', '#~.#D'], True],
   [[-1, -1, -1, -1, 3], [12, -1, -1, 4, -1]]),
  ('regression neighbour wall test #3',
   [['~#.~', '.D~#', '###~', '#~#D', '.##.'], False],
   [[-1, 0, -1, -1], [-1, -1, -1, 0], [6, 10, 12, -1], [1, -1, 5, -1], [-1, 2, 9, -1]]),
  ('vertical wall pair #1', [['#', '#'], False], [[4], [1]]),
  ('lone wall at edge #1', [['#'], True], [[15]]),
  ('control #1', [['.'], True], [[-1]])]]
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 fixtureActualExpectedOutcome
door next to wall #1[[2, -1]][[0, -1]]Failed
regression neighbour wall test #1[[-1, 3, -1], [12, -1, -1]][[-1, 1, -1], [12, -1, -1]]Failed
regression neighbour wall test #2[[-1, 15, 15, 11], [15, 15, -1, -1], [-1, -1, -1, -1], [15, -1, 9, -1], [13, -1, -1, 6]][[-1, 7, 11, 11], [10, 9, -1, -1], [-1, -1, -1, -1], [12, -1, 0, -1], [13, -1, -1, 6]]Failed
regression neighbour wall test #3[[11, 11, -1], [-1, -1, 7], [14, 14, -1]][[11, 9, -1], [-1, -1, 2], [14, 12, -1]]Failed
regression neighbour wall test #4[[2, 10, 10, 10, -1]][[2, 10, 10, 8, -1]]Failed
vertical wall pair #1[[4], [1]][[4], [1]]Passed
lone wall at edge #1[[15]][[15]]Passed
control #1[[-1], [-1]][[-1], [-1]]Passed

SHA-256 / 7172330129696ef65e46a2a781053fea150268cda06ca75e988bcdfb6261101e

2 / The unsuccessful fix

Exit 1
"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(grid, same_oob):
    h = len(grid)
    w = len(grid[0])
    out = []
    for r in range(h):
        row = []
        for c in range(w):
            if grid[r][c] != '#':
                row.append(-1)
                continue
            m = 0
            for bit, (dr, dc) in ((1, (-1, 0)), (2, (0, 1)), (4, (1, 0)), (8, (0, -1))):
                rr, cc = r + dr, c + dc
                if 0 <= rr < h and 0 <= cc < w:
                    if grid[rr][cc] in '#D':
                        m |= bit
                elif same_oob:
                    m |= bit
            row.append(m)
        out.append(row)
    return out
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
cases = [[('door next to wall #1', [['#D'], False], [[0, -1]]),
  ('regression neighbour wall test #1', [['.#D', '#.~'], True], [[-1, 1, -1], [12, -1, -1]]),
  ('regression neighbour wall test #2',
   [['~###', '##~.', 'D~~.', '#D#.', '#..#'], True],
   [[-1, 7, 11, 11], [10, 9, -1, -1], [-1, -1, -1, -1], [12, -1, 0, -1], [13, -1, -1, 6]]),
  ('regression neighbour wall test #3',
   [['##D', '..#', '##D'], True],
   [[11, 9, -1], [-1, -1, 2], [14, 12, -1]]),
  ('regression neighbour wall test #4', [['####D'], False], [[2, 10, 10, 8, -1]]),
  ('vertical wall pair #1', [['#', '#'], False], [[4], [1]]),
  ('lone wall at edge #1', [['#'], True], [[15]]),
  ('control #1', [['~', '~'], True], [[-1], [-1]])],
 [('door next to wall #1', [['#D'], False], [[0, -1]]),
  ('regression neighbour wall test #1',
   [['~###', '##~.', 'D~~.', '#D#.', '#..#'], True],
   [[-1, 7, 11, 11], [10, 9, -1, -1], [-1, -1, -1, -1], [12, -1, 0, -1], [13, -1, -1, 6]]),
  ('regression neighbour wall test #2',
   [['##D', '..#', '##D'], True],
   [[11, 9, -1], [-1, -1, 2], [14, 12, -1]]),
  ('regression neighbour wall test #3', [['####D'], False], [[2, 10, 10, 8, -1]]),
  ('regression neighbour wall test #4', [['D~#', '#~.'], False], [[-1, -1, 0], [0, -1, -1]]),
  ('vertical wall pair #1', [['#', '#'], False], [[4], [1]]),
  ('lone wall at edge #1', [['#'], True], [[15]]),
  ('control #1', [['~', '~'], True], [[-1], [-1]])],
 [('door next to wall #1', [['#D'], False], [[0, -1]]),
  ('regression neighbour wall test #1', [['####D'], False], [[2, 10, 10, 8, -1]]),
  ('regression neighbour wall test #2', [['D~#', '#~.'], False], [[-1, -1, 0], [0, -1, -1]]),
  ('regression neighbour wall test #3',
   [['##.D', '.D#~', '##..', '#.#~', '~D.#'], True],
   [[11, 9, -1, -1], [-1, -1, 0, -1], [14, 8, -1, -1], [9, -1, 0, -1], [-1, -1, -1, 6]]),
  ('regression neighbour wall test #4',
   [['#..D.', '.##.#', '..##D', 'D.#.D'], False],
   [[0, -1, -1, -1, -1], [-1, 2, 12, -1, 0], [-1, -1, 7, 8, -1], [-1, -1, 1, -1, -1]]),
  ('vertical wall pair #1', [['#', '#'], False], [[4], [1]]),
  ('lone wall at edge #1', [['#'], True], [[15]]),
  ('control #1', [['~', '~'], True], [[-1], [-1]])],
 [('door next to wall #1', [['#D'], False], [[0, -1]]),
  ('regression neighbour wall test #1',
   [['##.D', '.D#~', '##..', '#.#~', '~D.#'], True],
   [[11, 9, -1, -1], [-1, -1, 0, -1], [14, 8, -1, -1], [9, -1, 0, -1], [-1, -1, -1, 6]]),
  ('regression neighbour wall test #2',
   [['#..D.', '.##.#', '..##D', 'D.#.D'], False],
   [[0, -1, -1, -1, -1], [-1, 2, 12, -1, 0], [-1, -1, 7, 8, -1], [-1, -1, 1, -1, -1]]),
  ('regression neighbour wall test #3', [['~.#', '##D'], True], [[-1, -1, 3], [14, 12, -1]]),
  ('regression neighbour wall test #4',
   [['~D.D#', '#~.#D'], True],
   [[-1, -1, -1, -1, 3], [12, -1, -1, 4, -1]]),
  ('vertical wall pair #1', [['#', '#'], False], [[4], [1]]),
  ('lone wall at edge #1', [['#'], True], [[15]]),
  ('control #1', [['#', '#', '#'], False], [[4], [5], [1]])],
 [('door next to wall #1', [['#D'], False], [[0, -1]]),
  ('fault site neighbour wall test #1', [['~#', '.~', '.#'], True], [[-1, 3], [-1, -1], [-1, 6]]),
  ('regression neighbour wall test #1', [['~.#', '##D'], True], [[-1, -1, 3], [14, 12, -1]]),
  ('regression neighbour wall test #2',
   [['~D.D#', '#~.#D'], True],
   [[-1, -1, -1, -1, 3], [12, -1, -1, 4, -1]]),
  ('regression neighbour wall test #3',
   [['~#.~', '.D~#', '###~', '#~#D', '.##.'], False],
   [[-1, 0, -1, -1], [-1, -1, -1, 0], [6, 10, 12, -1], [1, -1, 5, -1], [-1, 2, 9, -1]]),
  ('vertical wall pair #1', [['#', '#'], False], [[4], [1]]),
  ('lone wall at edge #1', [['#'], True], [[15]]),
  ('control #1', [['.'], True], [[-1]])]]
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 fixtureActualExpectedOutcome
door next to wall #1[[2, -1]][[0, -1]]Failed
regression neighbour wall test #1[[-1, 3, -1], [12, -1, -1]][[-1, 1, -1], [12, -1, -1]]Failed
regression neighbour wall test #2[[-1, 7, 11, 11], [14, 9, -1, -1], [-1, -1, -1, -1], [15, -1, 8, -1], [13, -1, -1, 6]][[-1, 7, 11, 11], [10, 9, -1, -1], [-1, -1, -1, -1], [12, -1, 0, -1], [13, -1, -1, 6]]Failed
regression neighbour wall test #3[[11, 11, -1], [-1, -1, 7], [14, 14, -1]][[11, 9, -1], [-1, -1, 2], [14, 12, -1]]Failed
regression neighbour wall test #4[[2, 10, 10, 10, -1]][[2, 10, 10, 8, -1]]Failed
vertical wall pair #1[[4], [1]][[4], [1]]Passed
lone wall at edge #1[[15]][[15]]Passed
control #1[[-1], [-1]][[-1], [-1]]Passed

SHA-256 / 7ed1c4d01b4b9038b047fd49cbf6b64483e8e839d67dde69ba9567262a8a4b4e

3 / The verified repair

Exit 0
"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(grid, same_oob):
    h = len(grid)
    w = len(grid[0])
    out = []
    for r in range(h):
        row = []
        for c in range(w):
            if grid[r][c] != '#':
                row.append(-1)
                continue
            m = 0
            for bit, (dr, dc) in ((1, (-1, 0)), (2, (0, 1)), (4, (1, 0)), (8, (0, -1))):
                rr, cc = r + dr, c + dc
                if 0 <= rr < h and 0 <= cc < w:
                    if grid[rr][cc] == '#':
                        m |= bit
                elif same_oob:
                    m |= bit
            row.append(m)
        out.append(row)
    return out
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
cases = [[('door next to wall #1', [['#D'], False], [[0, -1]]),
  ('regression neighbour wall test #1', [['.#D', '#.~'], True], [[-1, 1, -1], [12, -1, -1]]),
  ('regression neighbour wall test #2',
   [['~###', '##~.', 'D~~.', '#D#.', '#..#'], True],
   [[-1, 7, 11, 11], [10, 9, -1, -1], [-1, -1, -1, -1], [12, -1, 0, -1], [13, -1, -1, 6]]),
  ('regression neighbour wall test #3',
   [['##D', '..#', '##D'], True],
   [[11, 9, -1], [-1, -1, 2], [14, 12, -1]]),
  ('regression neighbour wall test #4', [['####D'], False], [[2, 10, 10, 8, -1]]),
  ('vertical wall pair #1', [['#', '#'], False], [[4], [1]]),
  ('lone wall at edge #1', [['#'], True], [[15]]),
  ('control #1', [['~', '~'], True], [[-1], [-1]])],
 [('door next to wall #1', [['#D'], False], [[0, -1]]),
  ('regression neighbour wall test #1',
   [['~###', '##~.', 'D~~.', '#D#.', '#..#'], True],
   [[-1, 7, 11, 11], [10, 9, -1, -1], [-1, -1, -1, -1], [12, -1, 0, -1], [13, -1, -1, 6]]),
  ('regression neighbour wall test #2',
   [['##D', '..#', '##D'], True],
   [[11, 9, -1], [-1, -1, 2], [14, 12, -1]]),
  ('regression neighbour wall test #3', [['####D'], False], [[2, 10, 10, 8, -1]]),
  ('regression neighbour wall test #4', [['D~#', '#~.'], False], [[-1, -1, 0], [0, -1, -1]]),
  ('vertical wall pair #1', [['#', '#'], False], [[4], [1]]),
  ('lone wall at edge #1', [['#'], True], [[15]]),
  ('control #1', [['~', '~'], True], [[-1], [-1]])],
 [('door next to wall #1', [['#D'], False], [[0, -1]]),
  ('regression neighbour wall test #1', [['####D'], False], [[2, 10, 10, 8, -1]]),
  ('regression neighbour wall test #2', [['D~#', '#~.'], False], [[-1, -1, 0], [0, -1, -1]]),
  ('regression neighbour wall test #3',
   [['##.D', '.D#~', '##..', '#.#~', '~D.#'], True],
   [[11, 9, -1, -1], [-1, -1, 0, -1], [14, 8, -1, -1], [9, -1, 0, -1], [-1, -1, -1, 6]]),
  ('regression neighbour wall test #4',
   [['#..D.', '.##.#', '..##D', 'D.#.D'], False],
   [[0, -1, -1, -1, -1], [-1, 2, 12, -1, 0], [-1, -1, 7, 8, -1], [-1, -1, 1, -1, -1]]),
  ('vertical wall pair #1', [['#', '#'], False], [[4], [1]]),
  ('lone wall at edge #1', [['#'], True], [[15]]),
  ('control #1', [['~', '~'], True], [[-1], [-1]])],
 [('door next to wall #1', [['#D'], False], [[0, -1]]),
  ('regression neighbour wall test #1',
   [['##.D', '.D#~', '##..', '#.#~', '~D.#'], True],
   [[11, 9, -1, -1], [-1, -1, 0, -1], [14, 8, -1, -1], [9, -1, 0, -1], [-1, -1, -1, 6]]),
  ('regression neighbour wall test #2',
   [['#..D.', '.##.#', '..##D', 'D.#.D'], False],
   [[0, -1, -1, -1, -1], [-1, 2, 12, -1, 0], [-1, -1, 7, 8, -1], [-1, -1, 1, -1, -1]]),
  ('regression neighbour wall test #3', [['~.#', '##D'], True], [[-1, -1, 3], [14, 12, -1]]),
  ('regression neighbour wall test #4',
   [['~D.D#', '#~.#D'], True],
   [[-1, -1, -1, -1, 3], [12, -1, -1, 4, -1]]),
  ('vertical wall pair #1', [['#', '#'], False], [[4], [1]]),
  ('lone wall at edge #1', [['#'], True], [[15]]),
  ('control #1', [['#', '#', '#'], False], [[4], [5], [1]])],
 [('door next to wall #1', [['#D'], False], [[0, -1]]),
  ('fault site neighbour wall test #1', [['~#', '.~', '.#'], True], [[-1, 3], [-1, -1], [-1, 6]]),
  ('regression neighbour wall test #1', [['~.#', '##D'], True], [[-1, -1, 3], [14, 12, -1]]),
  ('regression neighbour wall test #2',
   [['~D.D#', '#~.#D'], True],
   [[-1, -1, -1, -1, 3], [12, -1, -1, 4, -1]]),
  ('regression neighbour wall test #3',
   [['~#.~', '.D~#', '###~', '#~#D', '.##.'], False],
   [[-1, 0, -1, -1], [-1, -1, -1, 0], [6, 10, 12, -1], [1, -1, 5, -1], [-1, 2, 9, -1]]),
  ('vertical wall pair #1', [['#', '#'], False], [[4], [1]]),
  ('lone wall at edge #1', [['#'], True], [[15]]),
  ('control #1', [['.'], True], [[-1]])]]
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 fixtureActualExpectedOutcome
door next to wall #1[[0, -1]][[0, -1]]Passed
regression neighbour wall test #1[[-1, 1, -1], [12, -1, -1]][[-1, 1, -1], [12, -1, -1]]Passed
regression neighbour wall test #2[[-1, 7, 11, 11], [10, 9, -1, -1], [-1, -1, -1, -1], [12, -1, 0, -1], [13, -1, -1, 6]][[-1, 7, 11, 11], [10, 9, -1, -1], [-1, -1, -1, -1], [12, -1, 0, -1], [13, -1, -1, 6]]Passed
regression neighbour wall test #3[[11, 9, -1], [-1, -1, 2], [14, 12, -1]][[11, 9, -1], [-1, -1, 2], [14, 12, -1]]Passed
regression neighbour wall test #4[[2, 10, 10, 8, -1]][[2, 10, 10, 8, -1]]Passed
vertical wall pair #1[[4], [1]][[4], [1]]Passed
lone wall at edge #1[[15]][[15]]Passed
control #1[[-1], [-1]][[-1], [-1]]Passed

SHA-256 / 3aba51309c1c0dd6727446368390851dfb638ad028aac0a456c037b266821711

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 2026-09-29T14:50:51.854842+00:00.

Case digest / 7f9b07eb110e52943fc621d91a13b7db0d3c45814d94c1ad17a04e922f0a56a4