FAILURE MAP
← Case archive

FA-37021 / Table interactions / Open access

Merged cell rendering: visible colspan · case 01

The table visible colspan result violates the stipulated merged cell rendering contract.

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

ROOT CAUSE

The visible colspan decision uses "'colspan':a['cs']" instead of "'colspan':len(cc)".

THE FAILURE

The visible colspan decision uses "'colspan':a['cs']" instead of "'colspan':len(cc)".

Unsuccessful approach: The attempted repair "'colspan':1" still loses a required part of the table contract.

Case contract

Merged rectangles are expressed in source coordinates, clipped to source bounds and visible rows/columns, rebased to the first visible cell, and accepted in declaration order only if disjoint; plain cells omit every accepted merged cell.

Why this case matters

An offline table UI model isolates merged cell rendering, including adversarial row/column relationships.

1 / The failure

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

N = 1
observations = []
def solve(rows, cols, anchors, hidden_rows, hidden_cols):
    vr=[r for r in rows if r not in hidden_rows]
    vc=[c for c in cols if c not in hidden_cols]
    result=[]
    covered=set()
    for a in anchors:
        rr=[r for r in rows[a['r']:a['r']+a['rs']] if r in vr]
        cc=[c for c in cols[a['c']:a['c']+a['cs']] if c in vc]
        if not rr or not cc: continue
        cells={(r,c) for r in rr for c in cc}
        if cells & covered: continue
        covered |= cells
        result.append({'anchor':[rr[0],cc[0]],'rowspan':len(rr),'colspan':a['cs'],'value':a['value'],'covered':sorted(cells-{(rr[0],cc[0])})})
    return {'merges':result,'plain':[(r,c) for r in vr for c in vc if (r,c) not in covered]}
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
if N == 1:
    check('nonzero origin', solve(['r0','r1','r2','r3'], ['a','b','c','d'], [{'r':1,'c':1,'rs':2,'cs':2,'value':1}], [], []), {'merges': [{'anchor': ['r1', 'b'], 'rowspan': 2, 'colspan': 2, 'value': 1, 'covered': [('r1', 'c'), ('r2', 'b'), ('r2', 'c')]}], 'plain': [('r0', 'a'), ('r0', 'b'), ('r0', 'c'), ('r0', 'd'), ('r1', 'a'), ('r1', 'd'), ('r2', 'a'), ('r2', 'd'), ('r3', 'a'), ('r3', 'b'), ('r3', 'c'), ('r3', 'd')]})
    check('hidden anchor', solve(['r0','r1','r2'], ['a','b','c'], [{'r':0,'c':0,'rs':3,'cs':3,'value':'x'}], ['r0','r1'], ['a','b']), {'merges': [{'anchor': ['r2', 'c'], 'rowspan': 1, 'colspan': 1, 'value': 'x', 'covered': []}], 'plain': []})
    check('partial overlap', solve(['r0','r1','r2'], ['a','b','c'], [{'r':0,'c':0,'rs':2,'cs':2,'value':'x'},{'r':1,'c':1,'rs':2,'cs':2,'value':'y'}], [], []), {'merges': [{'anchor': ['r0', 'a'], 'rowspan': 2, 'colspan': 2, 'value': 'x', 'covered': [('r0', 'b'), ('r1', 'a'), ('r1', 'b')]}], 'plain': [('r0', 'c'), ('r1', 'c'), ('r2', 'a'), ('r2', 'b'), ('r2', 'c')]})
    check('hidden merge', solve(['r0'], ['a'], [{'r':0,'c':0,'rs':1,'cs':1,'value':'x'}], ['r0'], []), {'merges': [], 'plain': []})
    check('clamped span', solve(['r0','r1'], ['a','b'], [{'r':1,'c':1,'rs':4,'cs':4,'value':'x'}], [], []), {'merges': [{'anchor': ['r1', 'b'], 'rowspan': 1, 'colspan': 1, 'value': 'x', 'covered': []}], 'plain': [('r0', 'a'), ('r0', 'b'), ('r1', 'a')]})
    check('unmerged grid', solve(['r0','r1'], ['a','b'], [], [], []), {'merges': [], 'plain': [('r0', 'a'), ('r0', 'b'), ('r1', 'a'), ('r1', 'b')]})

if N == 2:
    check('nonzero origin', solve(['r0','r1','r2','r3'], ['a','b','c','d'], [{'r':1,'c':1,'rs':2,'cs':2,'value':2}], [], []), {'merges': [{'anchor': ['r1', 'b'], 'rowspan': 2, 'colspan': 2, 'value': 2, 'covered': [('r1', 'c'), ('r2', 'b'), ('r2', 'c')]}], 'plain': [('r0', 'a'), ('r0', 'b'), ('r0', 'c'), ('r0', 'd'), ('r1', 'a'), ('r1', 'd'), ('r2', 'a'), ('r2', 'd'), ('r3', 'a'), ('r3', 'b'), ('r3', 'c'), ('r3', 'd')]})
    check('hidden anchor', solve(['r0','r1','r2'], ['a','b','c'], [{'r':0,'c':0,'rs':3,'cs':3,'value':'x'}], ['r0','r1'], ['a','b']), {'merges': [{'anchor': ['r2', 'c'], 'rowspan': 1, 'colspan': 1, 'value': 'x', 'covered': []}], 'plain': []})
    check('partial overlap', solve(['r0','r1','r2'], ['a','b','c'], [{'r':0,'c':0,'rs':2,'cs':2,'value':'x'},{'r':1,'c':1,'rs':2,'cs':2,'value':'y'}], [], []), {'merges': [{'anchor': ['r0', 'a'], 'rowspan': 2, 'colspan': 2, 'value': 'x', 'covered': [('r0', 'b'), ('r1', 'a'), ('r1', 'b')]}], 'plain': [('r0', 'c'), ('r1', 'c'), ('r2', 'a'), ('r2', 'b'), ('r2', 'c')]})
    check('hidden merge', solve(['r0'], ['a'], [{'r':0,'c':0,'rs':1,'cs':1,'value':'x'}], ['r0'], []), {'merges': [], 'plain': []})
    check('clamped span', solve(['r0','r1'], ['a','b'], [{'r':1,'c':1,'rs':4,'cs':4,'value':'x'}], [], []), {'merges': [{'anchor': ['r1', 'b'], 'rowspan': 1, 'colspan': 1, 'value': 'x', 'covered': []}], 'plain': [('r0', 'a'), ('r0', 'b'), ('r1', 'a')]})
    check('unmerged grid', solve(['r0','r1'], ['a','b'], [], [], []), {'merges': [], 'plain': [('r0', 'a'), ('r0', 'b'), ('r1', 'a'), ('r1', 'b')]})

if N == 3:
    check('nonzero origin', solve(['r0','r1','r2','r3'], ['a','b','c','d'], [{'r':1,'c':1,'rs':2,'cs':2,'value':3}], [], []), {'merges': [{'anchor': ['r1', 'b'], 'rowspan': 2, 'colspan': 2, 'value': 3, 'covered': [('r1', 'c'), ('r2', 'b'), ('r2', 'c')]}], 'plain': [('r0', 'a'), ('r0', 'b'), ('r0', 'c'), ('r0', 'd'), ('r1', 'a'), ('r1', 'd'), ('r2', 'a'), ('r2', 'd'), ('r3', 'a'), ('r3', 'b'), ('r3', 'c'), ('r3', 'd')]})
    check('hidden anchor', solve(['r0','r1','r2'], ['a','b','c'], [{'r':0,'c':0,'rs':3,'cs':3,'value':'x'}], ['r0','r1'], ['a','b']), {'merges': [{'anchor': ['r2', 'c'], 'rowspan': 1, 'colspan': 1, 'value': 'x', 'covered': []}], 'plain': []})
    check('partial overlap', solve(['r0','r1','r2'], ['a','b','c'], [{'r':0,'c':0,'rs':2,'cs':2,'value':'x'},{'r':1,'c':1,'rs':2,'cs':2,'value':'y'}], [], []), {'merges': [{'anchor': ['r0', 'a'], 'rowspan': 2, 'colspan': 2, 'value': 'x', 'covered': [('r0', 'b'), ('r1', 'a'), ('r1', 'b')]}], 'plain': [('r0', 'c'), ('r1', 'c'), ('r2', 'a'), ('r2', 'b'), ('r2', 'c')]})
    check('hidden merge', solve(['r0'], ['a'], [{'r':0,'c':0,'rs':1,'cs':1,'value':'x'}], ['r0'], []), {'merges': [], 'plain': []})
    check('clamped span', solve(['r0','r1'], ['a','b'], [{'r':1,'c':1,'rs':4,'cs':4,'value':'x'}], [], []), {'merges': [{'anchor': ['r1', 'b'], 'rowspan': 1, 'colspan': 1, 'value': 'x', 'covered': []}], 'plain': [('r0', 'a'), ('r0', 'b'), ('r1', 'a')]})
    check('unmerged grid', solve(['r0','r1'], ['a','b'], [], [], []), {'merges': [], 'plain': [('r0', 'a'), ('r0', 'b'), ('r1', 'a'), ('r1', 'b')]})

if N == 4:
    check('nonzero origin', solve(['r0','r1','r2','r3'], ['a','b','c','d'], [{'r':1,'c':1,'rs':2,'cs':2,'value':4}], [], []), {'merges': [{'anchor': ['r1', 'b'], 'rowspan': 2, 'colspan': 2, 'value': 4, 'covered': [('r1', 'c'), ('r2', 'b'), ('r2', 'c')]}], 'plain': [('r0', 'a'), ('r0', 'b'), ('r0', 'c'), ('r0', 'd'), ('r1', 'a'), ('r1', 'd'), ('r2', 'a'), ('r2', 'd'), ('r3', 'a'), ('r3', 'b'), ('r3', 'c'), ('r3', 'd')]})
    check('hidden anchor', solve(['r0','r1','r2'], ['a','b','c'], [{'r':0,'c':0,'rs':3,'cs':3,'value':'x'}], ['r0','r1'], ['a','b']), {'merges': [{'anchor': ['r2', 'c'], 'rowspan': 1, 'colspan': 1, 'value': 'x', 'covered': []}], 'plain': []})
    check('partial overlap', solve(['r0','r1','r2'], ['a','b','c'], [{'r':0,'c':0,'rs':2,'cs':2,'value':'x'},{'r':1,'c':1,'rs':2,'cs':2,'value':'y'}], [], []), {'merges': [{'anchor': ['r0', 'a'], 'rowspan': 2, 'colspan': 2, 'value': 'x', 'covered': [('r0', 'b'), ('r1', 'a'), ('r1', 'b')]}], 'plain': [('r0', 'c'), ('r1', 'c'), ('r2', 'a'), ('r2', 'b'), ('r2', 'c')]})
    check('hidden merge', solve(['r0'], ['a'], [{'r':0,'c':0,'rs':1,'cs':1,'value':'x'}], ['r0'], []), {'merges': [], 'plain': []})
    check('clamped span', solve(['r0','r1'], ['a','b'], [{'r':1,'c':1,'rs':4,'cs':4,'value':'x'}], [], []), {'merges': [{'anchor': ['r1', 'b'], 'rowspan': 1, 'colspan': 1, 'value': 'x', 'covered': []}], 'plain': [('r0', 'a'), ('r0', 'b'), ('r1', 'a')]})
    check('unmerged grid', solve(['r0','r1'], ['a','b'], [], [], []), {'merges': [], 'plain': [('r0', 'a'), ('r0', 'b'), ('r1', 'a'), ('r1', 'b')]})

if N == 5:
    check('nonzero origin', solve(['r0','r1','r2','r3'], ['a','b','c','d'], [{'r':1,'c':1,'rs':2,'cs':2,'value':5}], [], []), {'merges': [{'anchor': ['r1', 'b'], 'rowspan': 2, 'colspan': 2, 'value': 5, 'covered': [('r1', 'c'), ('r2', 'b'), ('r2', 'c')]}], 'plain': [('r0', 'a'), ('r0', 'b'), ('r0', 'c'), ('r0', 'd'), ('r1', 'a'), ('r1', 'd'), ('r2', 'a'), ('r2', 'd'), ('r3', 'a'), ('r3', 'b'), ('r3', 'c'), ('r3', 'd')]})
    check('hidden anchor', solve(['r0','r1','r2'], ['a','b','c'], [{'r':0,'c':0,'rs':3,'cs':3,'value':'x'}], ['r0','r1'], ['a','b']), {'merges': [{'anchor': ['r2', 'c'], 'rowspan': 1, 'colspan': 1, 'value': 'x', 'covered': []}], 'plain': []})
    check('partial overlap', solve(['r0','r1','r2'], ['a','b','c'], [{'r':0,'c':0,'rs':2,'cs':2,'value':'x'},{'r':1,'c':1,'rs':2,'cs':2,'value':'y'}], [], []), {'merges': [{'anchor': ['r0', 'a'], 'rowspan': 2, 'colspan': 2, 'value': 'x', 'covered': [('r0', 'b'), ('r1', 'a'), ('r1', 'b')]}], 'plain': [('r0', 'c'), ('r1', 'c'), ('r2', 'a'), ('r2', 'b'), ('r2', 'c')]})
    check('hidden merge', solve(['r0'], ['a'], [{'r':0,'c':0,'rs':1,'cs':1,'value':'x'}], ['r0'], []), {'merges': [], 'plain': []})
    check('clamped span', solve(['r0','r1'], ['a','b'], [{'r':1,'c':1,'rs':4,'cs':4,'value':'x'}], [], []), {'merges': [{'anchor': ['r1', 'b'], 'rowspan': 1, 'colspan': 1, 'value': 'x', 'covered': []}], 'plain': [('r0', 'a'), ('r0', 'b'), ('r1', 'a')]})
    check('unmerged grid', solve(['r0','r1'], ['a','b'], [], [], []), {'merges': [], 'plain': [('r0', 'a'), ('r0', 'b'), ('r1', 'a'), ('r1', 'b')]})

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
nonzero origin{'merges': [{'anchor': ['r1', 'b'], 'colspan': 2, 'covered': [['r1', 'c'], ['r2', 'b'], ['r2', 'c']], 'rowspan': 2, 'value': 1}], 'plain': [['r0', 'a'], ['r0', 'b'], ['r0', 'c'], ['r0', 'd'], ['r1', 'a'], ['r1', 'd'], ['r2', 'a'], ['r2', 'd'], ['r3', 'a'], ['r3', 'b'], ['r3', 'c'], ['r3', 'd']]}{'merges': [{'anchor': ['r1', 'b'], 'colspan': 2, 'covered': [['r1', 'c'], ['r2', 'b'], ['r2', 'c']], 'rowspan': 2, 'value': 1}], 'plain': [['r0', 'a'], ['r0', 'b'], ['r0', 'c'], ['r0', 'd'], ['r1', 'a'], ['r1', 'd'], ['r2', 'a'], ['r2', 'd'], ['r3', 'a'], ['r3', 'b'], ['r3', 'c'], ['r3', 'd']]}Passed
hidden anchor{'merges': [{'anchor': ['r2', 'c'], 'colspan': 3, 'covered': [], 'rowspan': 1, 'value': 'x'}], 'plain': []}{'merges': [{'anchor': ['r2', 'c'], 'colspan': 1, 'covered': [], 'rowspan': 1, 'value': 'x'}], 'plain': []}Failed
partial overlap{'merges': [{'anchor': ['r0', 'a'], 'colspan': 2, 'covered': [['r0', 'b'], ['r1', 'a'], ['r1', 'b']], 'rowspan': 2, 'value': 'x'}], 'plain': [['r0', 'c'], ['r1', 'c'], ['r2', 'a'], ['r2', 'b'], ['r2', 'c']]}{'merges': [{'anchor': ['r0', 'a'], 'colspan': 2, 'covered': [['r0', 'b'], ['r1', 'a'], ['r1', 'b']], 'rowspan': 2, 'value': 'x'}], 'plain': [['r0', 'c'], ['r1', 'c'], ['r2', 'a'], ['r2', 'b'], ['r2', 'c']]}Passed
hidden merge{'merges': [], 'plain': []}{'merges': [], 'plain': []}Passed
clamped span{'merges': [{'anchor': ['r1', 'b'], 'colspan': 4, 'covered': [], 'rowspan': 1, 'value': 'x'}], 'plain': [['r0', 'a'], ['r0', 'b'], ['r1', 'a']]}{'merges': [{'anchor': ['r1', 'b'], 'colspan': 1, 'covered': [], 'rowspan': 1, 'value': 'x'}], 'plain': [['r0', 'a'], ['r0', 'b'], ['r1', 'a']]}Failed
unmerged grid{'merges': [], 'plain': [['r0', 'a'], ['r0', 'b'], ['r1', 'a'], ['r1', 'b']]}{'merges': [], 'plain': [['r0', 'a'], ['r0', 'b'], ['r1', 'a'], ['r1', 'b']]}Passed

SHA-256 / 754342b7e93a7b69eaee1d7602b8a6ad5fc2047da63a15b62569d3d4b80209f8

2 / The unsuccessful fix

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

N = 1
observations = []
def solve(rows, cols, anchors, hidden_rows, hidden_cols):
    vr=[r for r in rows if r not in hidden_rows]
    vc=[c for c in cols if c not in hidden_cols]
    result=[]
    covered=set()
    for a in anchors:
        rr=[r for r in rows[a['r']:a['r']+a['rs']] if r in vr]
        cc=[c for c in cols[a['c']:a['c']+a['cs']] if c in vc]
        if not rr or not cc: continue
        cells={(r,c) for r in rr for c in cc}
        if cells & covered: continue
        covered |= cells
        result.append({'anchor':[rr[0],cc[0]],'rowspan':len(rr),'colspan':1,'value':a['value'],'covered':sorted(cells-{(rr[0],cc[0])})})
    return {'merges':result,'plain':[(r,c) for r in vr for c in vc if (r,c) not in covered]}
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
if N == 1:
    check('nonzero origin', solve(['r0','r1','r2','r3'], ['a','b','c','d'], [{'r':1,'c':1,'rs':2,'cs':2,'value':1}], [], []), {'merges': [{'anchor': ['r1', 'b'], 'rowspan': 2, 'colspan': 2, 'value': 1, 'covered': [('r1', 'c'), ('r2', 'b'), ('r2', 'c')]}], 'plain': [('r0', 'a'), ('r0', 'b'), ('r0', 'c'), ('r0', 'd'), ('r1', 'a'), ('r1', 'd'), ('r2', 'a'), ('r2', 'd'), ('r3', 'a'), ('r3', 'b'), ('r3', 'c'), ('r3', 'd')]})
    check('hidden anchor', solve(['r0','r1','r2'], ['a','b','c'], [{'r':0,'c':0,'rs':3,'cs':3,'value':'x'}], ['r0','r1'], ['a','b']), {'merges': [{'anchor': ['r2', 'c'], 'rowspan': 1, 'colspan': 1, 'value': 'x', 'covered': []}], 'plain': []})
    check('partial overlap', solve(['r0','r1','r2'], ['a','b','c'], [{'r':0,'c':0,'rs':2,'cs':2,'value':'x'},{'r':1,'c':1,'rs':2,'cs':2,'value':'y'}], [], []), {'merges': [{'anchor': ['r0', 'a'], 'rowspan': 2, 'colspan': 2, 'value': 'x', 'covered': [('r0', 'b'), ('r1', 'a'), ('r1', 'b')]}], 'plain': [('r0', 'c'), ('r1', 'c'), ('r2', 'a'), ('r2', 'b'), ('r2', 'c')]})
    check('hidden merge', solve(['r0'], ['a'], [{'r':0,'c':0,'rs':1,'cs':1,'value':'x'}], ['r0'], []), {'merges': [], 'plain': []})
    check('clamped span', solve(['r0','r1'], ['a','b'], [{'r':1,'c':1,'rs':4,'cs':4,'value':'x'}], [], []), {'merges': [{'anchor': ['r1', 'b'], 'rowspan': 1, 'colspan': 1, 'value': 'x', 'covered': []}], 'plain': [('r0', 'a'), ('r0', 'b'), ('r1', 'a')]})
    check('unmerged grid', solve(['r0','r1'], ['a','b'], [], [], []), {'merges': [], 'plain': [('r0', 'a'), ('r0', 'b'), ('r1', 'a'), ('r1', 'b')]})

if N == 2:
    check('nonzero origin', solve(['r0','r1','r2','r3'], ['a','b','c','d'], [{'r':1,'c':1,'rs':2,'cs':2,'value':2}], [], []), {'merges': [{'anchor': ['r1', 'b'], 'rowspan': 2, 'colspan': 2, 'value': 2, 'covered': [('r1', 'c'), ('r2', 'b'), ('r2', 'c')]}], 'plain': [('r0', 'a'), ('r0', 'b'), ('r0', 'c'), ('r0', 'd'), ('r1', 'a'), ('r1', 'd'), ('r2', 'a'), ('r2', 'd'), ('r3', 'a'), ('r3', 'b'), ('r3', 'c'), ('r3', 'd')]})
    check('hidden anchor', solve(['r0','r1','r2'], ['a','b','c'], [{'r':0,'c':0,'rs':3,'cs':3,'value':'x'}], ['r0','r1'], ['a','b']), {'merges': [{'anchor': ['r2', 'c'], 'rowspan': 1, 'colspan': 1, 'value': 'x', 'covered': []}], 'plain': []})
    check('partial overlap', solve(['r0','r1','r2'], ['a','b','c'], [{'r':0,'c':0,'rs':2,'cs':2,'value':'x'},{'r':1,'c':1,'rs':2,'cs':2,'value':'y'}], [], []), {'merges': [{'anchor': ['r0', 'a'], 'rowspan': 2, 'colspan': 2, 'value': 'x', 'covered': [('r0', 'b'), ('r1', 'a'), ('r1', 'b')]}], 'plain': [('r0', 'c'), ('r1', 'c'), ('r2', 'a'), ('r2', 'b'), ('r2', 'c')]})
    check('hidden merge', solve(['r0'], ['a'], [{'r':0,'c':0,'rs':1,'cs':1,'value':'x'}], ['r0'], []), {'merges': [], 'plain': []})
    check('clamped span', solve(['r0','r1'], ['a','b'], [{'r':1,'c':1,'rs':4,'cs':4,'value':'x'}], [], []), {'merges': [{'anchor': ['r1', 'b'], 'rowspan': 1, 'colspan': 1, 'value': 'x', 'covered': []}], 'plain': [('r0', 'a'), ('r0', 'b'), ('r1', 'a')]})
    check('unmerged grid', solve(['r0','r1'], ['a','b'], [], [], []), {'merges': [], 'plain': [('r0', 'a'), ('r0', 'b'), ('r1', 'a'), ('r1', 'b')]})

if N == 3:
    check('nonzero origin', solve(['r0','r1','r2','r3'], ['a','b','c','d'], [{'r':1,'c':1,'rs':2,'cs':2,'value':3}], [], []), {'merges': [{'anchor': ['r1', 'b'], 'rowspan': 2, 'colspan': 2, 'value': 3, 'covered': [('r1', 'c'), ('r2', 'b'), ('r2', 'c')]}], 'plain': [('r0', 'a'), ('r0', 'b'), ('r0', 'c'), ('r0', 'd'), ('r1', 'a'), ('r1', 'd'), ('r2', 'a'), ('r2', 'd'), ('r3', 'a'), ('r3', 'b'), ('r3', 'c'), ('r3', 'd')]})
    check('hidden anchor', solve(['r0','r1','r2'], ['a','b','c'], [{'r':0,'c':0,'rs':3,'cs':3,'value':'x'}], ['r0','r1'], ['a','b']), {'merges': [{'anchor': ['r2', 'c'], 'rowspan': 1, 'colspan': 1, 'value': 'x', 'covered': []}], 'plain': []})
    check('partial overlap', solve(['r0','r1','r2'], ['a','b','c'], [{'r':0,'c':0,'rs':2,'cs':2,'value':'x'},{'r':1,'c':1,'rs':2,'cs':2,'value':'y'}], [], []), {'merges': [{'anchor': ['r0', 'a'], 'rowspan': 2, 'colspan': 2, 'value': 'x', 'covered': [('r0', 'b'), ('r1', 'a'), ('r1', 'b')]}], 'plain': [('r0', 'c'), ('r1', 'c'), ('r2', 'a'), ('r2', 'b'), ('r2', 'c')]})
    check('hidden merge', solve(['r0'], ['a'], [{'r':0,'c':0,'rs':1,'cs':1,'value':'x'}], ['r0'], []), {'merges': [], 'plain': []})
    check('clamped span', solve(['r0','r1'], ['a','b'], [{'r':1,'c':1,'rs':4,'cs':4,'value':'x'}], [], []), {'merges': [{'anchor': ['r1', 'b'], 'rowspan': 1, 'colspan': 1, 'value': 'x', 'covered': []}], 'plain': [('r0', 'a'), ('r0', 'b'), ('r1', 'a')]})
    check('unmerged grid', solve(['r0','r1'], ['a','b'], [], [], []), {'merges': [], 'plain': [('r0', 'a'), ('r0', 'b'), ('r1', 'a'), ('r1', 'b')]})

if N == 4:
    check('nonzero origin', solve(['r0','r1','r2','r3'], ['a','b','c','d'], [{'r':1,'c':1,'rs':2,'cs':2,'value':4}], [], []), {'merges': [{'anchor': ['r1', 'b'], 'rowspan': 2, 'colspan': 2, 'value': 4, 'covered': [('r1', 'c'), ('r2', 'b'), ('r2', 'c')]}], 'plain': [('r0', 'a'), ('r0', 'b'), ('r0', 'c'), ('r0', 'd'), ('r1', 'a'), ('r1', 'd'), ('r2', 'a'), ('r2', 'd'), ('r3', 'a'), ('r3', 'b'), ('r3', 'c'), ('r3', 'd')]})
    check('hidden anchor', solve(['r0','r1','r2'], ['a','b','c'], [{'r':0,'c':0,'rs':3,'cs':3,'value':'x'}], ['r0','r1'], ['a','b']), {'merges': [{'anchor': ['r2', 'c'], 'rowspan': 1, 'colspan': 1, 'value': 'x', 'covered': []}], 'plain': []})
    check('partial overlap', solve(['r0','r1','r2'], ['a','b','c'], [{'r':0,'c':0,'rs':2,'cs':2,'value':'x'},{'r':1,'c':1,'rs':2,'cs':2,'value':'y'}], [], []), {'merges': [{'anchor': ['r0', 'a'], 'rowspan': 2, 'colspan': 2, 'value': 'x', 'covered': [('r0', 'b'), ('r1', 'a'), ('r1', 'b')]}], 'plain': [('r0', 'c'), ('r1', 'c'), ('r2', 'a'), ('r2', 'b'), ('r2', 'c')]})
    check('hidden merge', solve(['r0'], ['a'], [{'r':0,'c':0,'rs':1,'cs':1,'value':'x'}], ['r0'], []), {'merges': [], 'plain': []})
    check('clamped span', solve(['r0','r1'], ['a','b'], [{'r':1,'c':1,'rs':4,'cs':4,'value':'x'}], [], []), {'merges': [{'anchor': ['r1', 'b'], 'rowspan': 1, 'colspan': 1, 'value': 'x', 'covered': []}], 'plain': [('r0', 'a'), ('r0', 'b'), ('r1', 'a')]})
    check('unmerged grid', solve(['r0','r1'], ['a','b'], [], [], []), {'merges': [], 'plain': [('r0', 'a'), ('r0', 'b'), ('r1', 'a'), ('r1', 'b')]})

if N == 5:
    check('nonzero origin', solve(['r0','r1','r2','r3'], ['a','b','c','d'], [{'r':1,'c':1,'rs':2,'cs':2,'value':5}], [], []), {'merges': [{'anchor': ['r1', 'b'], 'rowspan': 2, 'colspan': 2, 'value': 5, 'covered': [('r1', 'c'), ('r2', 'b'), ('r2', 'c')]}], 'plain': [('r0', 'a'), ('r0', 'b'), ('r0', 'c'), ('r0', 'd'), ('r1', 'a'), ('r1', 'd'), ('r2', 'a'), ('r2', 'd'), ('r3', 'a'), ('r3', 'b'), ('r3', 'c'), ('r3', 'd')]})
    check('hidden anchor', solve(['r0','r1','r2'], ['a','b','c'], [{'r':0,'c':0,'rs':3,'cs':3,'value':'x'}], ['r0','r1'], ['a','b']), {'merges': [{'anchor': ['r2', 'c'], 'rowspan': 1, 'colspan': 1, 'value': 'x', 'covered': []}], 'plain': []})
    check('partial overlap', solve(['r0','r1','r2'], ['a','b','c'], [{'r':0,'c':0,'rs':2,'cs':2,'value':'x'},{'r':1,'c':1,'rs':2,'cs':2,'value':'y'}], [], []), {'merges': [{'anchor': ['r0', 'a'], 'rowspan': 2, 'colspan': 2, 'value': 'x', 'covered': [('r0', 'b'), ('r1', 'a'), ('r1', 'b')]}], 'plain': [('r0', 'c'), ('r1', 'c'), ('r2', 'a'), ('r2', 'b'), ('r2', 'c')]})
    check('hidden merge', solve(['r0'], ['a'], [{'r':0,'c':0,'rs':1,'cs':1,'value':'x'}], ['r0'], []), {'merges': [], 'plain': []})
    check('clamped span', solve(['r0','r1'], ['a','b'], [{'r':1,'c':1,'rs':4,'cs':4,'value':'x'}], [], []), {'merges': [{'anchor': ['r1', 'b'], 'rowspan': 1, 'colspan': 1, 'value': 'x', 'covered': []}], 'plain': [('r0', 'a'), ('r0', 'b'), ('r1', 'a')]})
    check('unmerged grid', solve(['r0','r1'], ['a','b'], [], [], []), {'merges': [], 'plain': [('r0', 'a'), ('r0', 'b'), ('r1', 'a'), ('r1', 'b')]})

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
nonzero origin{'merges': [{'anchor': ['r1', 'b'], 'colspan': 1, 'covered': [['r1', 'c'], ['r2', 'b'], ['r2', 'c']], 'rowspan': 2, 'value': 1}], 'plain': [['r0', 'a'], ['r0', 'b'], ['r0', 'c'], ['r0', 'd'], ['r1', 'a'], ['r1', 'd'], ['r2', 'a'], ['r2', 'd'], ['r3', 'a'], ['r3', 'b'], ['r3', 'c'], ['r3', 'd']]}{'merges': [{'anchor': ['r1', 'b'], 'colspan': 2, 'covered': [['r1', 'c'], ['r2', 'b'], ['r2', 'c']], 'rowspan': 2, 'value': 1}], 'plain': [['r0', 'a'], ['r0', 'b'], ['r0', 'c'], ['r0', 'd'], ['r1', 'a'], ['r1', 'd'], ['r2', 'a'], ['r2', 'd'], ['r3', 'a'], ['r3', 'b'], ['r3', 'c'], ['r3', 'd']]}Failed
hidden anchor{'merges': [{'anchor': ['r2', 'c'], 'colspan': 1, 'covered': [], 'rowspan': 1, 'value': 'x'}], 'plain': []}{'merges': [{'anchor': ['r2', 'c'], 'colspan': 1, 'covered': [], 'rowspan': 1, 'value': 'x'}], 'plain': []}Passed
partial overlap{'merges': [{'anchor': ['r0', 'a'], 'colspan': 1, 'covered': [['r0', 'b'], ['r1', 'a'], ['r1', 'b']], 'rowspan': 2, 'value': 'x'}], 'plain': [['r0', 'c'], ['r1', 'c'], ['r2', 'a'], ['r2', 'b'], ['r2', 'c']]}{'merges': [{'anchor': ['r0', 'a'], 'colspan': 2, 'covered': [['r0', 'b'], ['r1', 'a'], ['r1', 'b']], 'rowspan': 2, 'value': 'x'}], 'plain': [['r0', 'c'], ['r1', 'c'], ['r2', 'a'], ['r2', 'b'], ['r2', 'c']]}Failed
hidden merge{'merges': [], 'plain': []}{'merges': [], 'plain': []}Passed
clamped span{'merges': [{'anchor': ['r1', 'b'], 'colspan': 1, 'covered': [], 'rowspan': 1, 'value': 'x'}], 'plain': [['r0', 'a'], ['r0', 'b'], ['r1', 'a']]}{'merges': [{'anchor': ['r1', 'b'], 'colspan': 1, 'covered': [], 'rowspan': 1, 'value': 'x'}], 'plain': [['r0', 'a'], ['r0', 'b'], ['r1', 'a']]}Passed
unmerged grid{'merges': [], 'plain': [['r0', 'a'], ['r0', 'b'], ['r1', 'a'], ['r1', 'b']]}{'merges': [], 'plain': [['r0', 'a'], ['r0', 'b'], ['r1', 'a'], ['r1', 'b']]}Passed

SHA-256 / e77eaa9213d32ff742fd5f70e047ba1f1c8dd1b01d28c0a2141fe9f5647e258a

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

Source axes have unique IDs; anchor origins are valid source indices and spans are positive integers. Deterministic offline table UI model; no browser, DOM, framework, or standards conformance is claimed. 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 2026-09-29T14:42:57.231986+00:00.

Case digest / 98b5f10862e1ebf1ea72fb9ae23eb258d95e4050ee422263f48892d2ae649a23