FAILURE MAP
← Case archive

FA-52421 / Raster memory layout / Open access

Indexed Nibble Records: Nibble write preservation mask selects replaced lane or one bit · case 01

The returned physical layout descriptor disagrees with the declared buffer mapping at keep_mask.

Verified by executionVariant 1 · 6 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

Nibble write preservation mask selects replaced lane or one bit The faulty expression is 15<<shift.

THE FAILURE

Nibble write preservation mask selects replaced lane or one bit The faulty expression is 15<<shift.

Unsuccessful approach: The attempted repair uses 255 ^ (1<<shift) and still violates the layout contract.

Case contract

An indexed image has a palette of three-byte entries, a two-byte palette-count field, and high-nibble-first pixels. Each scanline starts with a one-byte checksum. Odd final low nibbles are padding. Return the named intermediate layout descriptor and final address fields; all quantities are integer byte offsets unless explicitly stated.

Why this case matters

Offline raster resource, upload, readback, and storage-layout regression model.

1 / The failure

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

N = 1
observations = []
def solve(p):
    p = dict(p)
    palette_bytes = 2+p["colors"]*3
    packed_bytes = (p["w"]+1)//2
    row_pitch = packed_bytes+1
    image_origin = p["base"]+palette_bytes
    byte_address = image_origin+p["y"]*row_pitch+1+p["x"]//2
    shift = 4 if p["x"]%2==0 else 0
    keep_mask = 15<<shift
    written_byte = (p["old"]&keep_mask)|((p["value"]&15)<<shift)
    tail_mask = 240 if p["w"]%2 else 255
    allocation_end = image_origin+p["h"]*row_pitch
    return {'palette_bytes': palette_bytes, 'packed_bytes': packed_bytes, 'row_pitch': row_pitch, 'image_origin': image_origin, 'byte_address': byte_address, 'shift': shift, 'keep_mask': keep_mask, 'written_byte': written_byte, 'tail_mask': tail_mask, 'allocation_end': allocation_end}
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
cases = {1: [({'w': 4, 'h': 2, 'x': 0, 'y': 0, 'colors': 5, 'base': 17, 'value': 1, 'old': 35}, {'palette_bytes': 17, 'packed_bytes': 2, 'row_pitch': 3, 'image_origin': 34, 'byte_address': 35, 'shift': 4, 'keep_mask': 15, 'written_byte': 19, 'tail_mask': 255, 'allocation_end': 40}), ({'w': 5, 'h': 3, 'x': 1, 'y': 1, 'colors': 5, 'base': 17, 'value': 2, 'old': 36}, {'palette_bytes': 17, 'packed_bytes': 3, 'row_pitch': 4, 'image_origin': 34, 'byte_address': 39, 'shift': 0, 'keep_mask': 240, 'written_byte': 34, 'tail_mask': 240, 'allocation_end': 46}), ({'w': 6, 'h': 4, 'x': 2, 'y': 2, 'colors': 5, 'base': 17, 'value': 3, 'old': 37}, {'palette_bytes': 17, 'packed_bytes': 3, 'row_pitch': 4, 'image_origin': 34, 'byte_address': 44, 'shift': 4, 'keep_mask': 15, 'written_byte': 53, 'tail_mask': 255, 'allocation_end': 50}), ({'w': 7, 'h': 5, 'x': 3, 'y': 3, 'colors': 5, 'base': 17, 'value': 4, 'old': 38}, {'palette_bytes': 17, 'packed_bytes': 4, 'row_pitch': 5, 'image_origin': 34, 'byte_address': 51, 'shift': 0, 'keep_mask': 240, 'written_byte': 36, 'tail_mask': 240, 'allocation_end': 59}), ({'w': 8, 'h': 6, 'x': 4, 'y': 4, 'colors': 5, 'base': 17, 'value': 5, 'old': 39}, {'palette_bytes': 17, 'packed_bytes': 4, 'row_pitch': 5, 'image_origin': 34, 'byte_address': 57, 'shift': 4, 'keep_mask': 15, 'written_byte': 87, 'tail_mask': 255, 'allocation_end': 64}), ({'w': 9, 'h': 7, 'x': 5, 'y': 5, 'colors': 5, 'base': 17, 'value': 6, 'old': 40}, {'palette_bytes': 17, 'packed_bytes': 5, 'row_pitch': 6, 'image_origin': 34, 'byte_address': 67, 'shift': 0, 'keep_mask': 240, 'written_byte': 38, 'tail_mask': 240, 'allocation_end': 76})], 2: [({'w': 5, 'h': 2, 'x': 0, 'y': 0, 'colors': 6, 'base': 34, 'value': 2, 'old': 35}, {'palette_bytes': 20, 'packed_bytes': 3, 'row_pitch': 4, 'image_origin': 54, 'byte_address': 55, 'shift': 4, 'keep_mask': 15, 'written_byte': 35, 'tail_mask': 240, 'allocation_end': 62}), ({'w': 6, 'h': 3, 'x': 1, 'y': 1, 'colors': 6, 'base': 34, 'value': 3, 'old': 36}, {'palette_bytes': 20, 'packed_bytes': 3, 'row_pitch': 4, 'image_origin': 54, 'byte_address': 59, 'shift': 0, 'keep_mask': 240, 'written_byte': 35, 'tail_mask': 255, 'allocation_end': 66}), ({'w': 7, 'h': 4, 'x': 2, 'y': 2, 'colors': 6, 'base': 34, 'value': 4, 'old': 37}, {'palette_bytes': 20, 'packed_bytes': 4, 'row_pitch': 5, 'image_origin': 54, 'byte_address': 66, 'shift': 4, 'keep_mask': 15, 'written_byte': 69, 'tail_mask': 240, 'allocation_end': 74}), ({'w': 8, 'h': 5, 'x': 3, 'y': 3, 'colors': 6, 'base': 34, 'value': 5, 'old': 38}, {'palette_bytes': 20, 'packed_bytes': 4, 'row_pitch': 5, 'image_origin': 54, 'byte_address': 71, 'shift': 0, 'keep_mask': 240, 'written_byte': 37, 'tail_mask': 255, 'allocation_end': 79}), ({'w': 9, 'h': 6, 'x': 4, 'y': 4, 'colors': 6, 'base': 34, 'value': 6, 'old': 39}, {'palette_bytes': 20, 'packed_bytes': 5, 'row_pitch': 6, 'image_origin': 54, 'byte_address': 81, 'shift': 4, 'keep_mask': 15, 'written_byte': 103, 'tail_mask': 240, 'allocation_end': 90}), ({'w': 10, 'h': 7, 'x': 5, 'y': 5, 'colors': 6, 'base': 34, 'value': 7, 'old': 40}, {'palette_bytes': 20, 'packed_bytes': 5, 'row_pitch': 6, 'image_origin': 54, 'byte_address': 87, 'shift': 0, 'keep_mask': 240, 'written_byte': 39, 'tail_mask': 255, 'allocation_end': 96})], 3: [({'w': 6, 'h': 2, 'x': 0, 'y': 0, 'colors': 7, 'base': 51, 'value': 3, 'old': 35}, {'palette_bytes': 23, 'packed_bytes': 3, 'row_pitch': 4, 'image_origin': 74, 'byte_address': 75, 'shift': 4, 'keep_mask': 15, 'written_byte': 51, 'tail_mask': 255, 'allocation_end': 82}), ({'w': 7, 'h': 3, 'x': 1, 'y': 1, 'colors': 7, 'base': 51, 'value': 4, 'old': 36}, {'palette_bytes': 23, 'packed_bytes': 4, 'row_pitch': 5, 'image_origin': 74, 'byte_address': 80, 'shift': 0, 'keep_mask': 240, 'written_byte': 36, 'tail_mask': 240, 'allocation_end': 89}), ({'w': 8, 'h': 4, 'x': 2, 'y': 2, 'colors': 7, 'base': 51, 'value': 5, 'old': 37}, {'palette_bytes': 23, 'packed_bytes': 4, 'row_pitch': 5, 'image_origin': 74, 'byte_address': 86, 'shift': 4, 'keep_mask': 15, 'written_byte': 85, 'tail_mask': 255, 'allocation_end': 94}), ({'w': 9, 'h': 5, 'x': 3, 'y': 3, 'colors': 7, 'base': 51, 'value': 6, 'old': 38}, {'palette_bytes': 23, 'packed_bytes': 5, 'row_pitch': 6, 'image_origin': 74, 'byte_address': 94, 'shift': 0, 'keep_mask': 240, 'written_byte': 38, 'tail_mask': 240, 'allocation_end': 104}), ({'w': 10, 'h': 6, 'x': 4, 'y': 4, 'colors': 7, 'base': 51, 'value': 7, 'old': 39}, {'palette_bytes': 23, 'packed_bytes': 5, 'row_pitch': 6, 'image_origin': 74, 'byte_address': 101, 'shift': 4, 'keep_mask': 15, 'written_byte': 119, 'tail_mask': 255, 'allocation_end': 110}), ({'w': 11, 'h': 7, 'x': 5, 'y': 5, 'colors': 7, 'base': 51, 'value': 8, 'old': 40}, {'palette_bytes': 23, 'packed_bytes': 6, 'row_pitch': 7, 'image_origin': 74, 'byte_address': 112, 'shift': 0, 'keep_mask': 240, 'written_byte': 40, 'tail_mask': 240, 'allocation_end': 123})], 4: [({'w': 7, 'h': 2, 'x': 0, 'y': 0, 'colors': 8, 'base': 68, 'value': 4, 'old': 35}, {'palette_bytes': 26, 'packed_bytes': 4, 'row_pitch': 5, 'image_origin': 94, 'byte_address': 95, 'shift': 4, 'keep_mask': 15, 'written_byte': 67, 'tail_mask': 240, 'allocation_end': 104}), ({'w': 8, 'h': 3, 'x': 1, 'y': 1, 'colors': 8, 'base': 68, 'value': 5, 'old': 36}, {'palette_bytes': 26, 'packed_bytes': 4, 'row_pitch': 5, 'image_origin': 94, 'byte_address': 100, 'shift': 0, 'keep_mask': 240, 'written_byte': 37, 'tail_mask': 255, 'allocation_end': 109}), ({'w': 9, 'h': 4, 'x': 2, 'y': 2, 'colors': 8, 'base': 68, 'value': 6, 'old': 37}, {'palette_bytes': 26, 'packed_bytes': 5, 'row_pitch': 6, 'image_origin': 94, 'byte_address': 108, 'shift': 4, 'keep_mask': 15, 'written_byte': 101, 'tail_mask': 240, 'allocation_end': 118}), ({'w': 10, 'h': 5, 'x': 3, 'y': 3, 'colors': 8, 'base': 68, 'value': 7, 'old': 38}, {'palette_bytes': 26, 'packed_bytes': 5, 'row_pitch': 6, 'image_origin': 94, 'byte_address': 114, 'shift': 0, 'keep_mask': 240, 'written_byte': 39, 'tail_mask': 255, 'allocation_end': 124}), ({'w': 11, 'h': 6, 'x': 4, 'y': 4, 'colors': 8, 'base': 68, 'value': 8, 'old': 39}, {'palette_bytes': 26, 'packed_bytes': 6, 'row_pitch': 7, 'image_origin': 94, 'byte_address': 125, 'shift': 4, 'keep_mask': 15, 'written_byte': 135, 'tail_mask': 240, 'allocation_end': 136}), ({'w': 12, 'h': 7, 'x': 5, 'y': 5, 'colors': 8, 'base': 68, 'value': 9, 'old': 40}, {'palette_bytes': 26, 'packed_bytes': 6, 'row_pitch': 7, 'image_origin': 94, 'byte_address': 132, 'shift': 0, 'keep_mask': 240, 'written_byte': 41, 'tail_mask': 255, 'allocation_end': 143})], 5: [({'w': 8, 'h': 2, 'x': 0, 'y': 0, 'colors': 9, 'base': 85, 'value': 5, 'old': 35}, {'palette_bytes': 29, 'packed_bytes': 4, 'row_pitch': 5, 'image_origin': 114, 'byte_address': 115, 'shift': 4, 'keep_mask': 15, 'written_byte': 83, 'tail_mask': 255, 'allocation_end': 124}), ({'w': 9, 'h': 3, 'x': 1, 'y': 1, 'colors': 9, 'base': 85, 'value': 6, 'old': 36}, {'palette_bytes': 29, 'packed_bytes': 5, 'row_pitch': 6, 'image_origin': 114, 'byte_address': 121, 'shift': 0, 'keep_mask': 240, 'written_byte': 38, 'tail_mask': 240, 'allocation_end': 132}), ({'w': 10, 'h': 4, 'x': 2, 'y': 2, 'colors': 9, 'base': 85, 'value': 7, 'old': 37}, {'palette_bytes': 29, 'packed_bytes': 5, 'row_pitch': 6, 'image_origin': 114, 'byte_address': 128, 'shift': 4, 'keep_mask': 15, 'written_byte': 117, 'tail_mask': 255, 'allocation_end': 138}), ({'w': 11, 'h': 5, 'x': 3, 'y': 3, 'colors': 9, 'base': 85, 'value': 8, 'old': 38}, {'palette_bytes': 29, 'packed_bytes': 6, 'row_pitch': 7, 'image_origin': 114, 'byte_address': 137, 'shift': 0, 'keep_mask': 240, 'written_byte': 40, 'tail_mask': 240, 'allocation_end': 149}), ({'w': 12, 'h': 6, 'x': 4, 'y': 4, 'colors': 9, 'base': 85, 'value': 9, 'old': 39}, {'palette_bytes': 29, 'packed_bytes': 6, 'row_pitch': 7, 'image_origin': 114, 'byte_address': 145, 'shift': 4, 'keep_mask': 15, 'written_byte': 151, 'tail_mask': 255, 'allocation_end': 156}), ({'w': 13, 'h': 7, 'x': 5, 'y': 5, 'colors': 9, 'base': 85, 'value': 10, 'old': 40}, {'palette_bytes': 29, 'packed_bytes': 7, 'row_pitch': 8, 'image_origin': 114, 'byte_address': 157, 'shift': 0, 'keep_mask': 240, 'written_byte': 42, 'tail_mask': 240, 'allocation_end': 170})]}
for i, (p, expected) in enumerate(cases[N]):
    check("layout fixture " + str(i + 1), solve(p), 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
layout fixture 1{'allocation_end': 40, 'byte_address': 35, 'image_origin': 34, 'keep_mask': 240, 'packed_bytes': 2, 'palette_bytes': 17, 'row_pitch': 3, 'shift': 4, 'tail_mask': 255, 'written_byte': 48}{'allocation_end': 40, 'byte_address': 35, 'image_origin': 34, 'keep_mask': 15, 'packed_bytes': 2, 'palette_bytes': 17, 'row_pitch': 3, 'shift': 4, 'tail_mask': 255, 'written_byte': 19}Failed
layout fixture 2{'allocation_end': 46, 'byte_address': 39, 'image_origin': 34, 'keep_mask': 15, 'packed_bytes': 3, 'palette_bytes': 17, 'row_pitch': 4, 'shift': 0, 'tail_mask': 240, 'written_byte': 6}{'allocation_end': 46, 'byte_address': 39, 'image_origin': 34, 'keep_mask': 240, 'packed_bytes': 3, 'palette_bytes': 17, 'row_pitch': 4, 'shift': 0, 'tail_mask': 240, 'written_byte': 34}Failed
layout fixture 3{'allocation_end': 50, 'byte_address': 44, 'image_origin': 34, 'keep_mask': 240, 'packed_bytes': 3, 'palette_bytes': 17, 'row_pitch': 4, 'shift': 4, 'tail_mask': 255, 'written_byte': 48}{'allocation_end': 50, 'byte_address': 44, 'image_origin': 34, 'keep_mask': 15, 'packed_bytes': 3, 'palette_bytes': 17, 'row_pitch': 4, 'shift': 4, 'tail_mask': 255, 'written_byte': 53}Failed
layout fixture 4{'allocation_end': 59, 'byte_address': 51, 'image_origin': 34, 'keep_mask': 15, 'packed_bytes': 4, 'palette_bytes': 17, 'row_pitch': 5, 'shift': 0, 'tail_mask': 240, 'written_byte': 6}{'allocation_end': 59, 'byte_address': 51, 'image_origin': 34, 'keep_mask': 240, 'packed_bytes': 4, 'palette_bytes': 17, 'row_pitch': 5, 'shift': 0, 'tail_mask': 240, 'written_byte': 36}Failed
layout fixture 5{'allocation_end': 64, 'byte_address': 57, 'image_origin': 34, 'keep_mask': 240, 'packed_bytes': 4, 'palette_bytes': 17, 'row_pitch': 5, 'shift': 4, 'tail_mask': 255, 'written_byte': 112}{'allocation_end': 64, 'byte_address': 57, 'image_origin': 34, 'keep_mask': 15, 'packed_bytes': 4, 'palette_bytes': 17, 'row_pitch': 5, 'shift': 4, 'tail_mask': 255, 'written_byte': 87}Failed
layout fixture 6{'allocation_end': 76, 'byte_address': 67, 'image_origin': 34, 'keep_mask': 15, 'packed_bytes': 5, 'palette_bytes': 17, 'row_pitch': 6, 'shift': 0, 'tail_mask': 240, 'written_byte': 14}{'allocation_end': 76, 'byte_address': 67, 'image_origin': 34, 'keep_mask': 240, 'packed_bytes': 5, 'palette_bytes': 17, 'row_pitch': 6, 'shift': 0, 'tail_mask': 240, 'written_byte': 38}Failed

SHA-256 / c8d1cf54e708569960276fe18668a08bba15477fabddbc51bd6ec34348da8abc

2 / The unsuccessful fix

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

N = 1
observations = []
def solve(p):
    p = dict(p)
    palette_bytes = 2+p["colors"]*3
    packed_bytes = (p["w"]+1)//2
    row_pitch = packed_bytes+1
    image_origin = p["base"]+palette_bytes
    byte_address = image_origin+p["y"]*row_pitch+1+p["x"]//2
    shift = 4 if p["x"]%2==0 else 0
    keep_mask = 255 ^ (1<<shift)
    written_byte = (p["old"]&keep_mask)|((p["value"]&15)<<shift)
    tail_mask = 240 if p["w"]%2 else 255
    allocation_end = image_origin+p["h"]*row_pitch
    return {'palette_bytes': palette_bytes, 'packed_bytes': packed_bytes, 'row_pitch': row_pitch, 'image_origin': image_origin, 'byte_address': byte_address, 'shift': shift, 'keep_mask': keep_mask, 'written_byte': written_byte, 'tail_mask': tail_mask, 'allocation_end': allocation_end}
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
cases = {1: [({'w': 4, 'h': 2, 'x': 0, 'y': 0, 'colors': 5, 'base': 17, 'value': 1, 'old': 35}, {'palette_bytes': 17, 'packed_bytes': 2, 'row_pitch': 3, 'image_origin': 34, 'byte_address': 35, 'shift': 4, 'keep_mask': 15, 'written_byte': 19, 'tail_mask': 255, 'allocation_end': 40}), ({'w': 5, 'h': 3, 'x': 1, 'y': 1, 'colors': 5, 'base': 17, 'value': 2, 'old': 36}, {'palette_bytes': 17, 'packed_bytes': 3, 'row_pitch': 4, 'image_origin': 34, 'byte_address': 39, 'shift': 0, 'keep_mask': 240, 'written_byte': 34, 'tail_mask': 240, 'allocation_end': 46}), ({'w': 6, 'h': 4, 'x': 2, 'y': 2, 'colors': 5, 'base': 17, 'value': 3, 'old': 37}, {'palette_bytes': 17, 'packed_bytes': 3, 'row_pitch': 4, 'image_origin': 34, 'byte_address': 44, 'shift': 4, 'keep_mask': 15, 'written_byte': 53, 'tail_mask': 255, 'allocation_end': 50}), ({'w': 7, 'h': 5, 'x': 3, 'y': 3, 'colors': 5, 'base': 17, 'value': 4, 'old': 38}, {'palette_bytes': 17, 'packed_bytes': 4, 'row_pitch': 5, 'image_origin': 34, 'byte_address': 51, 'shift': 0, 'keep_mask': 240, 'written_byte': 36, 'tail_mask': 240, 'allocation_end': 59}), ({'w': 8, 'h': 6, 'x': 4, 'y': 4, 'colors': 5, 'base': 17, 'value': 5, 'old': 39}, {'palette_bytes': 17, 'packed_bytes': 4, 'row_pitch': 5, 'image_origin': 34, 'byte_address': 57, 'shift': 4, 'keep_mask': 15, 'written_byte': 87, 'tail_mask': 255, 'allocation_end': 64}), ({'w': 9, 'h': 7, 'x': 5, 'y': 5, 'colors': 5, 'base': 17, 'value': 6, 'old': 40}, {'palette_bytes': 17, 'packed_bytes': 5, 'row_pitch': 6, 'image_origin': 34, 'byte_address': 67, 'shift': 0, 'keep_mask': 240, 'written_byte': 38, 'tail_mask': 240, 'allocation_end': 76})], 2: [({'w': 5, 'h': 2, 'x': 0, 'y': 0, 'colors': 6, 'base': 34, 'value': 2, 'old': 35}, {'palette_bytes': 20, 'packed_bytes': 3, 'row_pitch': 4, 'image_origin': 54, 'byte_address': 55, 'shift': 4, 'keep_mask': 15, 'written_byte': 35, 'tail_mask': 240, 'allocation_end': 62}), ({'w': 6, 'h': 3, 'x': 1, 'y': 1, 'colors': 6, 'base': 34, 'value': 3, 'old': 36}, {'palette_bytes': 20, 'packed_bytes': 3, 'row_pitch': 4, 'image_origin': 54, 'byte_address': 59, 'shift': 0, 'keep_mask': 240, 'written_byte': 35, 'tail_mask': 255, 'allocation_end': 66}), ({'w': 7, 'h': 4, 'x': 2, 'y': 2, 'colors': 6, 'base': 34, 'value': 4, 'old': 37}, {'palette_bytes': 20, 'packed_bytes': 4, 'row_pitch': 5, 'image_origin': 54, 'byte_address': 66, 'shift': 4, 'keep_mask': 15, 'written_byte': 69, 'tail_mask': 240, 'allocation_end': 74}), ({'w': 8, 'h': 5, 'x': 3, 'y': 3, 'colors': 6, 'base': 34, 'value': 5, 'old': 38}, {'palette_bytes': 20, 'packed_bytes': 4, 'row_pitch': 5, 'image_origin': 54, 'byte_address': 71, 'shift': 0, 'keep_mask': 240, 'written_byte': 37, 'tail_mask': 255, 'allocation_end': 79}), ({'w': 9, 'h': 6, 'x': 4, 'y': 4, 'colors': 6, 'base': 34, 'value': 6, 'old': 39}, {'palette_bytes': 20, 'packed_bytes': 5, 'row_pitch': 6, 'image_origin': 54, 'byte_address': 81, 'shift': 4, 'keep_mask': 15, 'written_byte': 103, 'tail_mask': 240, 'allocation_end': 90}), ({'w': 10, 'h': 7, 'x': 5, 'y': 5, 'colors': 6, 'base': 34, 'value': 7, 'old': 40}, {'palette_bytes': 20, 'packed_bytes': 5, 'row_pitch': 6, 'image_origin': 54, 'byte_address': 87, 'shift': 0, 'keep_mask': 240, 'written_byte': 39, 'tail_mask': 255, 'allocation_end': 96})], 3: [({'w': 6, 'h': 2, 'x': 0, 'y': 0, 'colors': 7, 'base': 51, 'value': 3, 'old': 35}, {'palette_bytes': 23, 'packed_bytes': 3, 'row_pitch': 4, 'image_origin': 74, 'byte_address': 75, 'shift': 4, 'keep_mask': 15, 'written_byte': 51, 'tail_mask': 255, 'allocation_end': 82}), ({'w': 7, 'h': 3, 'x': 1, 'y': 1, 'colors': 7, 'base': 51, 'value': 4, 'old': 36}, {'palette_bytes': 23, 'packed_bytes': 4, 'row_pitch': 5, 'image_origin': 74, 'byte_address': 80, 'shift': 0, 'keep_mask': 240, 'written_byte': 36, 'tail_mask': 240, 'allocation_end': 89}), ({'w': 8, 'h': 4, 'x': 2, 'y': 2, 'colors': 7, 'base': 51, 'value': 5, 'old': 37}, {'palette_bytes': 23, 'packed_bytes': 4, 'row_pitch': 5, 'image_origin': 74, 'byte_address': 86, 'shift': 4, 'keep_mask': 15, 'written_byte': 85, 'tail_mask': 255, 'allocation_end': 94}), ({'w': 9, 'h': 5, 'x': 3, 'y': 3, 'colors': 7, 'base': 51, 'value': 6, 'old': 38}, {'palette_bytes': 23, 'packed_bytes': 5, 'row_pitch': 6, 'image_origin': 74, 'byte_address': 94, 'shift': 0, 'keep_mask': 240, 'written_byte': 38, 'tail_mask': 240, 'allocation_end': 104}), ({'w': 10, 'h': 6, 'x': 4, 'y': 4, 'colors': 7, 'base': 51, 'value': 7, 'old': 39}, {'palette_bytes': 23, 'packed_bytes': 5, 'row_pitch': 6, 'image_origin': 74, 'byte_address': 101, 'shift': 4, 'keep_mask': 15, 'written_byte': 119, 'tail_mask': 255, 'allocation_end': 110}), ({'w': 11, 'h': 7, 'x': 5, 'y': 5, 'colors': 7, 'base': 51, 'value': 8, 'old': 40}, {'palette_bytes': 23, 'packed_bytes': 6, 'row_pitch': 7, 'image_origin': 74, 'byte_address': 112, 'shift': 0, 'keep_mask': 240, 'written_byte': 40, 'tail_mask': 240, 'allocation_end': 123})], 4: [({'w': 7, 'h': 2, 'x': 0, 'y': 0, 'colors': 8, 'base': 68, 'value': 4, 'old': 35}, {'palette_bytes': 26, 'packed_bytes': 4, 'row_pitch': 5, 'image_origin': 94, 'byte_address': 95, 'shift': 4, 'keep_mask': 15, 'written_byte': 67, 'tail_mask': 240, 'allocation_end': 104}), ({'w': 8, 'h': 3, 'x': 1, 'y': 1, 'colors': 8, 'base': 68, 'value': 5, 'old': 36}, {'palette_bytes': 26, 'packed_bytes': 4, 'row_pitch': 5, 'image_origin': 94, 'byte_address': 100, 'shift': 0, 'keep_mask': 240, 'written_byte': 37, 'tail_mask': 255, 'allocation_end': 109}), ({'w': 9, 'h': 4, 'x': 2, 'y': 2, 'colors': 8, 'base': 68, 'value': 6, 'old': 37}, {'palette_bytes': 26, 'packed_bytes': 5, 'row_pitch': 6, 'image_origin': 94, 'byte_address': 108, 'shift': 4, 'keep_mask': 15, 'written_byte': 101, 'tail_mask': 240, 'allocation_end': 118}), ({'w': 10, 'h': 5, 'x': 3, 'y': 3, 'colors': 8, 'base': 68, 'value': 7, 'old': 38}, {'palette_bytes': 26, 'packed_bytes': 5, 'row_pitch': 6, 'image_origin': 94, 'byte_address': 114, 'shift': 0, 'keep_mask': 240, 'written_byte': 39, 'tail_mask': 255, 'allocation_end': 124}), ({'w': 11, 'h': 6, 'x': 4, 'y': 4, 'colors': 8, 'base': 68, 'value': 8, 'old': 39}, {'palette_bytes': 26, 'packed_bytes': 6, 'row_pitch': 7, 'image_origin': 94, 'byte_address': 125, 'shift': 4, 'keep_mask': 15, 'written_byte': 135, 'tail_mask': 240, 'allocation_end': 136}), ({'w': 12, 'h': 7, 'x': 5, 'y': 5, 'colors': 8, 'base': 68, 'value': 9, 'old': 40}, {'palette_bytes': 26, 'packed_bytes': 6, 'row_pitch': 7, 'image_origin': 94, 'byte_address': 132, 'shift': 0, 'keep_mask': 240, 'written_byte': 41, 'tail_mask': 255, 'allocation_end': 143})], 5: [({'w': 8, 'h': 2, 'x': 0, 'y': 0, 'colors': 9, 'base': 85, 'value': 5, 'old': 35}, {'palette_bytes': 29, 'packed_bytes': 4, 'row_pitch': 5, 'image_origin': 114, 'byte_address': 115, 'shift': 4, 'keep_mask': 15, 'written_byte': 83, 'tail_mask': 255, 'allocation_end': 124}), ({'w': 9, 'h': 3, 'x': 1, 'y': 1, 'colors': 9, 'base': 85, 'value': 6, 'old': 36}, {'palette_bytes': 29, 'packed_bytes': 5, 'row_pitch': 6, 'image_origin': 114, 'byte_address': 121, 'shift': 0, 'keep_mask': 240, 'written_byte': 38, 'tail_mask': 240, 'allocation_end': 132}), ({'w': 10, 'h': 4, 'x': 2, 'y': 2, 'colors': 9, 'base': 85, 'value': 7, 'old': 37}, {'palette_bytes': 29, 'packed_bytes': 5, 'row_pitch': 6, 'image_origin': 114, 'byte_address': 128, 'shift': 4, 'keep_mask': 15, 'written_byte': 117, 'tail_mask': 255, 'allocation_end': 138}), ({'w': 11, 'h': 5, 'x': 3, 'y': 3, 'colors': 9, 'base': 85, 'value': 8, 'old': 38}, {'palette_bytes': 29, 'packed_bytes': 6, 'row_pitch': 7, 'image_origin': 114, 'byte_address': 137, 'shift': 0, 'keep_mask': 240, 'written_byte': 40, 'tail_mask': 240, 'allocation_end': 149}), ({'w': 12, 'h': 6, 'x': 4, 'y': 4, 'colors': 9, 'base': 85, 'value': 9, 'old': 39}, {'palette_bytes': 29, 'packed_bytes': 6, 'row_pitch': 7, 'image_origin': 114, 'byte_address': 145, 'shift': 4, 'keep_mask': 15, 'written_byte': 151, 'tail_mask': 255, 'allocation_end': 156}), ({'w': 13, 'h': 7, 'x': 5, 'y': 5, 'colors': 9, 'base': 85, 'value': 10, 'old': 40}, {'palette_bytes': 29, 'packed_bytes': 7, 'row_pitch': 8, 'image_origin': 114, 'byte_address': 157, 'shift': 0, 'keep_mask': 240, 'written_byte': 42, 'tail_mask': 240, 'allocation_end': 170})]}
for i, (p, expected) in enumerate(cases[N]):
    check("layout fixture " + str(i + 1), solve(p), 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
layout fixture 1{'allocation_end': 40, 'byte_address': 35, 'image_origin': 34, 'keep_mask': 239, 'packed_bytes': 2, 'palette_bytes': 17, 'row_pitch': 3, 'shift': 4, 'tail_mask': 255, 'written_byte': 51}{'allocation_end': 40, 'byte_address': 35, 'image_origin': 34, 'keep_mask': 15, 'packed_bytes': 2, 'palette_bytes': 17, 'row_pitch': 3, 'shift': 4, 'tail_mask': 255, 'written_byte': 19}Failed
layout fixture 2{'allocation_end': 46, 'byte_address': 39, 'image_origin': 34, 'keep_mask': 254, 'packed_bytes': 3, 'palette_bytes': 17, 'row_pitch': 4, 'shift': 0, 'tail_mask': 240, 'written_byte': 38}{'allocation_end': 46, 'byte_address': 39, 'image_origin': 34, 'keep_mask': 240, 'packed_bytes': 3, 'palette_bytes': 17, 'row_pitch': 4, 'shift': 0, 'tail_mask': 240, 'written_byte': 34}Failed
layout fixture 3{'allocation_end': 50, 'byte_address': 44, 'image_origin': 34, 'keep_mask': 239, 'packed_bytes': 3, 'palette_bytes': 17, 'row_pitch': 4, 'shift': 4, 'tail_mask': 255, 'written_byte': 53}{'allocation_end': 50, 'byte_address': 44, 'image_origin': 34, 'keep_mask': 15, 'packed_bytes': 3, 'palette_bytes': 17, 'row_pitch': 4, 'shift': 4, 'tail_mask': 255, 'written_byte': 53}Failed
layout fixture 4{'allocation_end': 59, 'byte_address': 51, 'image_origin': 34, 'keep_mask': 254, 'packed_bytes': 4, 'palette_bytes': 17, 'row_pitch': 5, 'shift': 0, 'tail_mask': 240, 'written_byte': 38}{'allocation_end': 59, 'byte_address': 51, 'image_origin': 34, 'keep_mask': 240, 'packed_bytes': 4, 'palette_bytes': 17, 'row_pitch': 5, 'shift': 0, 'tail_mask': 240, 'written_byte': 36}Failed
layout fixture 5{'allocation_end': 64, 'byte_address': 57, 'image_origin': 34, 'keep_mask': 239, 'packed_bytes': 4, 'palette_bytes': 17, 'row_pitch': 5, 'shift': 4, 'tail_mask': 255, 'written_byte': 119}{'allocation_end': 64, 'byte_address': 57, 'image_origin': 34, 'keep_mask': 15, 'packed_bytes': 4, 'palette_bytes': 17, 'row_pitch': 5, 'shift': 4, 'tail_mask': 255, 'written_byte': 87}Failed
layout fixture 6{'allocation_end': 76, 'byte_address': 67, 'image_origin': 34, 'keep_mask': 254, 'packed_bytes': 5, 'palette_bytes': 17, 'row_pitch': 6, 'shift': 0, 'tail_mask': 240, 'written_byte': 46}{'allocation_end': 76, 'byte_address': 67, 'image_origin': 34, 'keep_mask': 240, 'packed_bytes': 5, 'palette_bytes': 17, 'row_pitch': 6, 'shift': 0, 'tail_mask': 240, 'written_byte': 38}Failed

SHA-256 / 83f344f842020fbd573b71bfc84abe08a85a8ab446ab3bc035e321d1a2aa1533

HELD IN THE MEMBER ARCHIVE

The verified repair and its recorded checks are member-only.

This mechanism has 6 recorded checks per implementation. The open-access tier publishes the failure and the unsuccessful fix; the repaired source that passes every check, and the observations that prove it, are available to members.

Every case sharing this mechanism uses the same contract and the same repair, so this one record is held back for all of them.

Member access is invitation-based. Sign in with your invited account to inspect the repair.

Sign in to the archive ↗

Verification & scope

Stipulated deterministic toy buffer layout; not a graphics API, codec, GPU vendor tiling specification, or hardware-conformance claim. Inputs satisfy the dimensions and bounds stated by the model. 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 2026-09-29T14:45:28.847815+00:00.

Case digest / 1fa98d6f8d5d3ff1bb97aeba28bba169000aa1b4e07db6ffd706c010baaa76fe