FA-78851 / Image orientation metadata / Open access

Pixel bake swaps the transpose and transverse tags · case 01

Selfies saved with tag 5 are baked rotated 180 degrees from the intended upright view.

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

ROOT CAUSE

The tag-5 branch uses the transverse formula grid[h-1-c][w-1-r], which belongs to tag 7.

VERIFIED REPAIR

Use the plain transpose grid[c][r] for tag 5 and keep the double reversal for tag 7.

Unsuccessful approach: Sampling grid[r][c] copies the stored layout into swapped dimensions instead of transposing it.

Case contract

Bake an EXIF-style orientation tag (1..8) into a row-major pixel grid so the result displays upright. Tags 2/4 mirror horizontally/vertically, 3 rotates 180, 6 rotates 90 clockwise, 8 rotates 90 counter-clockwise, 5 transposes and 7 transverses; tags outside 1..8 are treated as 1. Tags 5..8 swap the output width and height.

Why this case matters

Camera, phone and scanner images carry an orientation hint separately from the stored pixels; galleries, thumbnailers, editors and upload pipelines must interpret it consistently or photos appear sideways, mirrored or doubly rotated.

1 / The failure

Exit 1

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

N = 1
observations = []
def solve(grid, tag):
    h = len(grid)
    w = len(grid[0]) if h else 0
    if tag not in range(1, 9):
        tag = 1
    if tag in (5, 6, 7, 8):
        out_h, out_w = w, h
    else:
        out_h, out_w = h, w
    out = []
    for r in range(out_h):
        row = []
        for c in range(out_w):
            if tag == 1:
                v = grid[r][c]
            elif tag == 2:
                v = grid[r][w - 1 - c]
            elif tag == 3:
                v = grid[h - 1 - r][w - 1 - c]
            elif tag == 4:
                v = grid[h - 1 - r][c]
            elif tag == 5:
                v = grid[h - 1 - c][w - 1 - r]
            elif tag == 6:
                v = grid[h - 1 - c][r]
            elif tag == 7:
                v = grid[h - 1 - c][w - 1 - r]
            else:
                v = grid[c][w - 1 - r]
            row.append(v)
        out.append(row)
    return out
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[[([[1, 2, 3, 4], [11, 12, 13, 14], [21, 22, 23, 24], [31, 32, 33, 34]], 5), [[1, 11, 21, 31], [2, 12, 22, 32], [3, 13, 23, 33], [4, 14, 24, 34]]], [([[1, 2, 3], [11, 12, 13], [21, 22, 23]], 5), [[1, 11, 21], [2, 12, 22], [3, 13, 23]]], [([[1, 2, 3, 4], [11, 12, 13, 14], [21, 22, 23, 24], [31, 32, 33, 34]], 6), [[31, 21, 11, 1], [32, 22, 12, 2], [33, 23, 13, 3], [34, 24, 14, 4]]], [([[1], [11], [21], [31]], 8), [[1, 11, 21, 31]]], [([[1, 2, 3], [11, 12, 13], [21, 22, 23]], 6), [[21, 11, 1], [22, 12, 2], [23, 13, 3]]], [([[1, 2, 3, 4]], 2), [[4, 3, 2, 1]]], [([[1, 2], [11, 12], [21, 22], [31, 32]], 2), [[2, 1], [12, 11], [22, 21], [32, 31]]], [([[1, 2, 3]], 4), [[1, 2, 3]]]], [[([[2, 3, 4, 5], [12, 13, 14, 15], [22, 23, 24, 25], [32, 33, 34, 35]], 5), [[2, 12, 22, 32], [3, 13, 23, 33], [4, 14, 24, 34], [5, 15, 25, 35]]], [([[2, 3, 4], [12, 13, 14], [22, 23, 24]], 5), [[2, 12, 22], [3, 13, 23], [4, 14, 24]]], [([[2, 3, 4, 5], [12, 13, 14, 15]], 9), [[2, 3, 4, 5], [12, 13, 14, 15]]], [([[2, 3, 4], [12, 13, 14], [22, 23, 24]], 0), [[2, 3, 4], [12, 13, 14], [22, 23, 24]]], [([[2, 3, 4], [12, 13, 14], [22, 23, 24], [32, 33, 34]], 6), [[32, 22, 12, 2], [33, 23, 13, 3], [34, 24, 14, 4]]], [([[2]], 1), [[2]]], [([[2, 3, 4, 5], [12, 13, 14, 15]], 6), [[12, 2], [13, 3], [14, 4], [15, 5]]], [([[2, 3], [12, 13]], 5), [[2, 12], [3, 13]]]], [[([[3, 4, 5], [13, 14, 15], [23, 24, 25]], 5), [[3, 13, 23], [4, 14, 24], [5, 15, 25]]], [([[3, 4], [13, 14]], 5), [[3, 13], [4, 14]]], [([[3, 4, 5, 6]], 8), [[6], [5], [4], [3]]], [([[3, 4], [13, 14], [23, 24], [33, 34]], 8), [[4, 14, 24, 34], [3, 13, 23, 33]]], [([[3]], 8), [[3]]], [([[3, 4], [13, 14], [23, 24]], 6), [[23, 13, 3], [24, 14, 4]]], [([[3, 4, 5, 6], [13, 14, 15, 16], [23, 24, 25, 26]], 8), [[6, 16, 26], [5, 15, 25], [4, 14, 24], [3, 13, 23]]], [([[3], [13], [23], [33]], 6), [[33, 23, 13, 3]]]], [[([[4, 5, 6, 7], [14, 15, 16, 17], [24, 25, 26, 27], [34, 35, 36, 37]], 5), [[4, 14, 24, 34], [5, 15, 25, 35], [6, 16, 26, 36], [7, 17, 27, 37]]], [([[4, 5], [14, 15]], 5), [[4, 14], [5, 15]]], [([[4, 5, 6, 7], [14, 15, 16, 17], [24, 25, 26, 27]], 9), [[4, 5, 6, 7], [14, 15, 16, 17], [24, 25, 26, 27]]], [([[4, 5, 6], [14, 15, 16]], 3), [[16, 15, 14], [6, 5, 4]]], [([[4, 5, 6, 7], [14, 15, 16, 17], [24, 25, 26, 27], [34, 35, 36, 37]], 9), [[4, 5, 6, 7], [14, 15, 16, 17], [24, 25, 26, 27], [34, 35, 36, 37]]], [([[4]], 5), [[4]]], [([[4], [14]], 6), [[14, 4]]], [([[4, 5, 6]], 1), [[4, 5, 6]]]], [[([[5, 6], [15, 16]], 5), [[5, 15], [6, 16]]], [([[5, 6, 7], [15, 16, 17], [25, 26, 27]], 5), [[5, 15, 25], [6, 16, 26], [7, 17, 27]]], [([[5], [15], [25]], 2), [[5], [15], [25]]], [([[5], [15]], 4), [[15], [5]]], [([[5, 6]], 9), [[5, 6]]], [([[5]], 6), [[5]]], [([[5], [15], [25], [35]], 2), [[5], [15], [25], [35]]], [([[5, 6, 7, 8], [15, 16, 17, 18]], 3), [[18, 17, 16, 15], [8, 7, 6, 5]]]]]
labels = ["regression: tag 5 transpose branch", "repair trap", "combined fault", "control", "control", "boundary", "boundary", "control"]
for i, (args, expected) in enumerate(fixtures[N-1]):
    check("%s %d" % (labels[i % len(labels)], i), 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
regression: tag 5 transpose branch 0	`[[34, 24, 14, 4], [33, 23, 13, 3], [32, 22, 12, 2], [31, 21, 11, 1]]`	`[[1, 11, 21, 31], [2, 12, 22, 32], [3, 13, 23, 33], [4, 14, 24, 34]]`	Failed
repair trap 1	`[[23, 13, 3], [22, 12, 2], [21, 11, 1]]`	`[[1, 11, 21], [2, 12, 22], [3, 13, 23]]`	Failed
combined fault 2	`[[31, 21, 11, 1], [32, 22, 12, 2], [33, 23, 13, 3], [34, 24, 14, 4]]`	`[[31, 21, 11, 1], [32, 22, 12, 2], [33, 23, 13, 3], [34, 24, 14, 4]]`	Passed
control 3	`[[1, 11, 21, 31]]`	`[[1, 11, 21, 31]]`	Passed
control 4	`[[21, 11, 1], [22, 12, 2], [23, 13, 3]]`	`[[21, 11, 1], [22, 12, 2], [23, 13, 3]]`	Passed
boundary 5	`[[4, 3, 2, 1]]`	`[[4, 3, 2, 1]]`	Passed
boundary 6	`[[2, 1], [12, 11], [22, 21], [32, 31]]`	`[[2, 1], [12, 11], [22, 21], [32, 31]]`	Passed
control 7	`[[1, 2, 3]]`	`[[1, 2, 3]]`	Passed

SHA-256 / 4f0f7062301792c38da37dd23be80967ce018b17f56e8367900655beec9c82c8

2 / The unsuccessful fix

Exit 1

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

N = 1
observations = []
def solve(grid, tag):
    h = len(grid)
    w = len(grid[0]) if h else 0
    if tag not in range(1, 9):
        tag = 1
    if tag in (5, 6, 7, 8):
        out_h, out_w = w, h
    else:
        out_h, out_w = h, w
    out = []
    for r in range(out_h):
        row = []
        for c in range(out_w):
            if tag == 1:
                v = grid[r][c]
            elif tag == 2:
                v = grid[r][w - 1 - c]
            elif tag == 3:
                v = grid[h - 1 - r][w - 1 - c]
            elif tag == 4:
                v = grid[h - 1 - r][c]
            elif tag == 5:
                v = grid[r][c]
            elif tag == 6:
                v = grid[h - 1 - c][r]
            elif tag == 7:
                v = grid[h - 1 - c][w - 1 - r]
            else:
                v = grid[c][w - 1 - r]
            row.append(v)
        out.append(row)
    return out
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[[([[1, 2, 3, 4], [11, 12, 13, 14], [21, 22, 23, 24], [31, 32, 33, 34]], 5), [[1, 11, 21, 31], [2, 12, 22, 32], [3, 13, 23, 33], [4, 14, 24, 34]]], [([[1, 2, 3], [11, 12, 13], [21, 22, 23]], 5), [[1, 11, 21], [2, 12, 22], [3, 13, 23]]], [([[1, 2, 3, 4], [11, 12, 13, 14], [21, 22, 23, 24], [31, 32, 33, 34]], 6), [[31, 21, 11, 1], [32, 22, 12, 2], [33, 23, 13, 3], [34, 24, 14, 4]]], [([[1], [11], [21], [31]], 8), [[1, 11, 21, 31]]], [([[1, 2, 3], [11, 12, 13], [21, 22, 23]], 6), [[21, 11, 1], [22, 12, 2], [23, 13, 3]]], [([[1, 2, 3, 4]], 2), [[4, 3, 2, 1]]], [([[1, 2], [11, 12], [21, 22], [31, 32]], 2), [[2, 1], [12, 11], [22, 21], [32, 31]]], [([[1, 2, 3]], 4), [[1, 2, 3]]]], [[([[2, 3, 4, 5], [12, 13, 14, 15], [22, 23, 24, 25], [32, 33, 34, 35]], 5), [[2, 12, 22, 32], [3, 13, 23, 33], [4, 14, 24, 34], [5, 15, 25, 35]]], [([[2, 3, 4], [12, 13, 14], [22, 23, 24]], 5), [[2, 12, 22], [3, 13, 23], [4, 14, 24]]], [([[2, 3, 4, 5], [12, 13, 14, 15]], 9), [[2, 3, 4, 5], [12, 13, 14, 15]]], [([[2, 3, 4], [12, 13, 14], [22, 23, 24]], 0), [[2, 3, 4], [12, 13, 14], [22, 23, 24]]], [([[2, 3, 4], [12, 13, 14], [22, 23, 24], [32, 33, 34]], 6), [[32, 22, 12, 2], [33, 23, 13, 3], [34, 24, 14, 4]]], [([[2]], 1), [[2]]], [([[2, 3, 4, 5], [12, 13, 14, 15]], 6), [[12, 2], [13, 3], [14, 4], [15, 5]]], [([[2, 3], [12, 13]], 5), [[2, 12], [3, 13]]]], [[([[3, 4, 5], [13, 14, 15], [23, 24, 25]], 5), [[3, 13, 23], [4, 14, 24], [5, 15, 25]]], [([[3, 4], [13, 14]], 5), [[3, 13], [4, 14]]], [([[3, 4, 5, 6]], 8), [[6], [5], [4], [3]]], [([[3, 4], [13, 14], [23, 24], [33, 34]], 8), [[4, 14, 24, 34], [3, 13, 23, 33]]], [([[3]], 8), [[3]]], [([[3, 4], [13, 14], [23, 24]], 6), [[23, 13, 3], [24, 14, 4]]], [([[3, 4, 5, 6], [13, 14, 15, 16], [23, 24, 25, 26]], 8), [[6, 16, 26], [5, 15, 25], [4, 14, 24], [3, 13, 23]]], [([[3], [13], [23], [33]], 6), [[33, 23, 13, 3]]]], [[([[4, 5, 6, 7], [14, 15, 16, 17], [24, 25, 26, 27], [34, 35, 36, 37]], 5), [[4, 14, 24, 34], [5, 15, 25, 35], [6, 16, 26, 36], [7, 17, 27, 37]]], [([[4, 5], [14, 15]], 5), [[4, 14], [5, 15]]], [([[4, 5, 6, 7], [14, 15, 16, 17], [24, 25, 26, 27]], 9), [[4, 5, 6, 7], [14, 15, 16, 17], [24, 25, 26, 27]]], [([[4, 5, 6], [14, 15, 16]], 3), [[16, 15, 14], [6, 5, 4]]], [([[4, 5, 6, 7], [14, 15, 16, 17], [24, 25, 26, 27], [34, 35, 36, 37]], 9), [[4, 5, 6, 7], [14, 15, 16, 17], [24, 25, 26, 27], [34, 35, 36, 37]]], [([[4]], 5), [[4]]], [([[4], [14]], 6), [[14, 4]]], [([[4, 5, 6]], 1), [[4, 5, 6]]]], [[([[5, 6], [15, 16]], 5), [[5, 15], [6, 16]]], [([[5, 6, 7], [15, 16, 17], [25, 26, 27]], 5), [[5, 15, 25], [6, 16, 26], [7, 17, 27]]], [([[5], [15], [25]], 2), [[5], [15], [25]]], [([[5], [15]], 4), [[15], [5]]], [([[5, 6]], 9), [[5, 6]]], [([[5]], 6), [[5]]], [([[5], [15], [25], [35]], 2), [[5], [15], [25], [35]]], [([[5, 6, 7, 8], [15, 16, 17, 18]], 3), [[18, 17, 16, 15], [8, 7, 6, 5]]]]]
labels = ["regression: tag 5 transpose branch", "repair trap", "combined fault", "control", "control", "boundary", "boundary", "control"]
for i, (args, expected) in enumerate(fixtures[N-1]):
    check("%s %d" % (labels[i % len(labels)], i), 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
regression: tag 5 transpose branch 0	`[[1, 2, 3, 4], [11, 12, 13, 14], [21, 22, 23, 24], [31, 32, 33, 34]]`	`[[1, 11, 21, 31], [2, 12, 22, 32], [3, 13, 23, 33], [4, 14, 24, 34]]`	Failed
repair trap 1	`[[1, 2, 3], [11, 12, 13], [21, 22, 23]]`	`[[1, 11, 21], [2, 12, 22], [3, 13, 23]]`	Failed
combined fault 2	`[[31, 21, 11, 1], [32, 22, 12, 2], [33, 23, 13, 3], [34, 24, 14, 4]]`	`[[31, 21, 11, 1], [32, 22, 12, 2], [33, 23, 13, 3], [34, 24, 14, 4]]`	Passed
control 3	`[[1, 11, 21, 31]]`	`[[1, 11, 21, 31]]`	Passed
control 4	`[[21, 11, 1], [22, 12, 2], [23, 13, 3]]`	`[[21, 11, 1], [22, 12, 2], [23, 13, 3]]`	Passed
boundary 5	`[[4, 3, 2, 1]]`	`[[4, 3, 2, 1]]`	Passed
boundary 6	`[[2, 1], [12, 11], [22, 21], [32, 31]]`	`[[2, 1], [12, 11], [22, 21], [32, 31]]`	Passed
control 7	`[[1, 2, 3]]`	`[[1, 2, 3]]`	Passed

SHA-256 / 75fa8637f3a51257e5540bba40c671875198252d4c806493b455084b3d7a62f6

3 / The verified repair

Exit 0

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

N = 1
observations = []
def solve(grid, tag):
    h = len(grid)
    w = len(grid[0]) if h else 0
    if tag not in range(1, 9):
        tag = 1
    if tag in (5, 6, 7, 8):
        out_h, out_w = w, h
    else:
        out_h, out_w = h, w
    out = []
    for r in range(out_h):
        row = []
        for c in range(out_w):
            if tag == 1:
                v = grid[r][c]
            elif tag == 2:
                v = grid[r][w - 1 - c]
            elif tag == 3:
                v = grid[h - 1 - r][w - 1 - c]
            elif tag == 4:
                v = grid[h - 1 - r][c]
            elif tag == 5:
                v = grid[c][r]
            elif tag == 6:
                v = grid[h - 1 - c][r]
            elif tag == 7:
                v = grid[h - 1 - c][w - 1 - r]
            else:
                v = grid[c][w - 1 - r]
            row.append(v)
        out.append(row)
    return out
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[[([[1, 2, 3, 4], [11, 12, 13, 14], [21, 22, 23, 24], [31, 32, 33, 34]], 5), [[1, 11, 21, 31], [2, 12, 22, 32], [3, 13, 23, 33], [4, 14, 24, 34]]], [([[1, 2, 3], [11, 12, 13], [21, 22, 23]], 5), [[1, 11, 21], [2, 12, 22], [3, 13, 23]]], [([[1, 2, 3, 4], [11, 12, 13, 14], [21, 22, 23, 24], [31, 32, 33, 34]], 6), [[31, 21, 11, 1], [32, 22, 12, 2], [33, 23, 13, 3], [34, 24, 14, 4]]], [([[1], [11], [21], [31]], 8), [[1, 11, 21, 31]]], [([[1, 2, 3], [11, 12, 13], [21, 22, 23]], 6), [[21, 11, 1], [22, 12, 2], [23, 13, 3]]], [([[1, 2, 3, 4]], 2), [[4, 3, 2, 1]]], [([[1, 2], [11, 12], [21, 22], [31, 32]], 2), [[2, 1], [12, 11], [22, 21], [32, 31]]], [([[1, 2, 3]], 4), [[1, 2, 3]]]], [[([[2, 3, 4, 5], [12, 13, 14, 15], [22, 23, 24, 25], [32, 33, 34, 35]], 5), [[2, 12, 22, 32], [3, 13, 23, 33], [4, 14, 24, 34], [5, 15, 25, 35]]], [([[2, 3, 4], [12, 13, 14], [22, 23, 24]], 5), [[2, 12, 22], [3, 13, 23], [4, 14, 24]]], [([[2, 3, 4, 5], [12, 13, 14, 15]], 9), [[2, 3, 4, 5], [12, 13, 14, 15]]], [([[2, 3, 4], [12, 13, 14], [22, 23, 24]], 0), [[2, 3, 4], [12, 13, 14], [22, 23, 24]]], [([[2, 3, 4], [12, 13, 14], [22, 23, 24], [32, 33, 34]], 6), [[32, 22, 12, 2], [33, 23, 13, 3], [34, 24, 14, 4]]], [([[2]], 1), [[2]]], [([[2, 3, 4, 5], [12, 13, 14, 15]], 6), [[12, 2], [13, 3], [14, 4], [15, 5]]], [([[2, 3], [12, 13]], 5), [[2, 12], [3, 13]]]], [[([[3, 4, 5], [13, 14, 15], [23, 24, 25]], 5), [[3, 13, 23], [4, 14, 24], [5, 15, 25]]], [([[3, 4], [13, 14]], 5), [[3, 13], [4, 14]]], [([[3, 4, 5, 6]], 8), [[6], [5], [4], [3]]], [([[3, 4], [13, 14], [23, 24], [33, 34]], 8), [[4, 14, 24, 34], [3, 13, 23, 33]]], [([[3]], 8), [[3]]], [([[3, 4], [13, 14], [23, 24]], 6), [[23, 13, 3], [24, 14, 4]]], [([[3, 4, 5, 6], [13, 14, 15, 16], [23, 24, 25, 26]], 8), [[6, 16, 26], [5, 15, 25], [4, 14, 24], [3, 13, 23]]], [([[3], [13], [23], [33]], 6), [[33, 23, 13, 3]]]], [[([[4, 5, 6, 7], [14, 15, 16, 17], [24, 25, 26, 27], [34, 35, 36, 37]], 5), [[4, 14, 24, 34], [5, 15, 25, 35], [6, 16, 26, 36], [7, 17, 27, 37]]], [([[4, 5], [14, 15]], 5), [[4, 14], [5, 15]]], [([[4, 5, 6, 7], [14, 15, 16, 17], [24, 25, 26, 27]], 9), [[4, 5, 6, 7], [14, 15, 16, 17], [24, 25, 26, 27]]], [([[4, 5, 6], [14, 15, 16]], 3), [[16, 15, 14], [6, 5, 4]]], [([[4, 5, 6, 7], [14, 15, 16, 17], [24, 25, 26, 27], [34, 35, 36, 37]], 9), [[4, 5, 6, 7], [14, 15, 16, 17], [24, 25, 26, 27], [34, 35, 36, 37]]], [([[4]], 5), [[4]]], [([[4], [14]], 6), [[14, 4]]], [([[4, 5, 6]], 1), [[4, 5, 6]]]], [[([[5, 6], [15, 16]], 5), [[5, 15], [6, 16]]], [([[5, 6, 7], [15, 16, 17], [25, 26, 27]], 5), [[5, 15, 25], [6, 16, 26], [7, 17, 27]]], [([[5], [15], [25]], 2), [[5], [15], [25]]], [([[5], [15]], 4), [[15], [5]]], [([[5, 6]], 9), [[5, 6]]], [([[5]], 6), [[5]]], [([[5], [15], [25], [35]], 2), [[5], [15], [25], [35]]], [([[5, 6, 7, 8], [15, 16, 17, 18]], 3), [[18, 17, 16, 15], [8, 7, 6, 5]]]]]
labels = ["regression: tag 5 transpose branch", "repair trap", "combined fault", "control", "control", "boundary", "boundary", "control"]
for i, (args, expected) in enumerate(fixtures[N-1]):
    check("%s %d" % (labels[i % len(labels)], i), 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
regression: tag 5 transpose branch 0	`[[1, 11, 21, 31], [2, 12, 22, 32], [3, 13, 23, 33], [4, 14, 24, 34]]`	`[[1, 11, 21, 31], [2, 12, 22, 32], [3, 13, 23, 33], [4, 14, 24, 34]]`	Passed
repair trap 1	`[[1, 11, 21], [2, 12, 22], [3, 13, 23]]`	`[[1, 11, 21], [2, 12, 22], [3, 13, 23]]`	Passed
combined fault 2	`[[31, 21, 11, 1], [32, 22, 12, 2], [33, 23, 13, 3], [34, 24, 14, 4]]`	`[[31, 21, 11, 1], [32, 22, 12, 2], [33, 23, 13, 3], [34, 24, 14, 4]]`	Passed
control 3	`[[1, 11, 21, 31]]`	`[[1, 11, 21, 31]]`	Passed
control 4	`[[21, 11, 1], [22, 12, 2], [23, 13, 3]]`	`[[21, 11, 1], [22, 12, 2], [23, 13, 3]]`	Passed
boundary 5	`[[4, 3, 2, 1]]`	`[[4, 3, 2, 1]]`	Passed
boundary 6	`[[2, 1], [12, 11], [22, 21], [32, 31]]`	`[[2, 1], [12, 11], [22, 21], [32, 31]]`	Passed
control 7	`[[1, 2, 3]]`	`[[1, 2, 3]]`	Passed

SHA-256 / e9cf6c413be2242b3f4d6025de53f7663891b27645267cf47709ee3b13c21958

Verification & scope

A deterministic bounded teaching model with a stipulated contract; it makes no claim of conformance to any published specification. 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 2026-09-29T14:49:39.224546+00:00.

Case digest / 444834e1d6b55d3f2e78e08fb5e76408f969b4f168f1cec6f6c21c3344729d4f