FA-75521 / Text diff and three-way merge / Open access

Diffstat histogram: small changes vanish from a scaled bar · case 01

A file with one changed line shows no marks next to a large file.

Verified by executionVariant 1 · 10 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

After scaling, counts that floor to zero are not raised to one mark.

THE FAILURE

After scaling, counts that floor to zero are not raised to one mark.

Unsuccessful approach: Raising zero counts unconditionally draws marks for insertions or deletions that did not happen.

Case contract

Files are [path, added, removed], with None counts for binary files. Each text file prints "path | total +++---"; when the largest total exceeds width, both counts scale by width/max with floor, but a non-zero count keeps at least one mark. Binary files print "path | Bin". The summary counts files and, when non-zero, insertions and deletions with singular/plural wording.

Why this case matters

Diffstat output is how reviewers size a change; scaling and pluralization rules are easy to get subtly wrong.

1 / The failure

Exit 1

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

N = 1
observations = []
def solve(files, width):
    mx = max([f[1] + f[2] for f in files if f[1] is not None] + [0])
    lines = []
    ins = dels = changed = 0
    for path, add, rem in files:
        changed += 1
        if add is None:
            lines.append('%s | Bin' % path)
            continue
        ins += add
        dels += rem
        if mx > width:
            pa = add * width // mx
            pr = rem * width // mx
        else:
            pa, pr = add, rem
        lines.append('%s | %d %s' % (path, add + rem, '+' * pa + '-' * pr))
    summary = '%d file%s changed' % (changed, '' if changed == 1 else 's')
    if ins:
        summary += ', %d insertion%s(+)' % (ins, '' if ins == 1 else 's')
    if dels:
        summary += ', %d deletion%s(-)' % (dels, '' if dels == 1 else 's')
    lines.append(summary)
    return lines
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
cases = {
    1: [('small changes without scaling', [[['a.txt', 3, 1]], 40], ['a.txt | 4 +++-', '1 file changed, 3 insertions(+), 1 deletion(-)']), ('scaled bar keeps small counts visible', [[['big.c', 200, 0], ['tiny.c', 1, 1]], 20], ['big.c | 200 ++++++++++++++++++++', 'tiny.c | 2 +-', '2 files changed, 201 insertions(+), 1 deletion(-)']), ('binary file', [[['logo.png', None, None], ['x', 2, 0]], 40], ['logo.png | Bin', 'x | 2 ++', '2 files changed, 2 insertions(+)']), ('single insertion grammar', [[['one', 1, 0]], 40], ['one | 1 +', '1 file changed, 1 insertion(+)']), ('only deletions', [[['gone', 0, 5]], 40], ['gone | 5 -----', '1 file changed, 5 deletions(-)']), ('scale uses the largest file', [[['f1', 30, 10], ['f2', 10, 0]], 10], ['f1 | 40 +++++++--', 'f2 | 10 ++', '2 files changed, 40 insertions(+), 10 deletions(-)']), ('several files', [[['p', 1, 0], ['q', 0, 1], ['r', 1, 1]], 5], ['p | 1 +', 'q | 1 -', 'r | 2 +-', '3 files changed, 2 insertions(+), 2 deletions(-)']), ('unscaled wide change', [[['w', 12, 3]], 15], ['w | 15 ++++++++++++---', '1 file changed, 12 insertions(+), 3 deletions(-)']), ('floor not rounding when scaling', [[['r', 7, 0], ['s', 20, 0]], 10], ['r | 7 +++', 's | 20 ++++++++++', '2 files changed, 27 insertions(+)']), ('binary-only change', [[['img1.png', None, None]], 40], ['img1.png | Bin', '1 file changed'])],
    2: [('small changes without scaling', [[['a.txt', 3, 1]], 40], ['a.txt | 4 +++-', '1 file changed, 3 insertions(+), 1 deletion(-)']), ('scaled bar keeps small counts visible', [[['big.c', 200, 0], ['tiny.c', 1, 1]], 20], ['big.c | 200 ++++++++++++++++++++', 'tiny.c | 2 +-', '2 files changed, 201 insertions(+), 1 deletion(-)']), ('binary file', [[['logo.png', None, None], ['x', 2, 0]], 40], ['logo.png | Bin', 'x | 2 ++', '2 files changed, 2 insertions(+)']), ('single insertion grammar', [[['one', 1, 0]], 40], ['one | 1 +', '1 file changed, 1 insertion(+)']), ('only deletions', [[['gone', 0, 6]], 40], ['gone | 6 ------', '1 file changed, 6 deletions(-)']), ('scale uses the largest file', [[['f1', 30, 10], ['f2', 20, 0]], 10], ['f1 | 40 +++++++--', 'f2 | 20 +++++', '2 files changed, 50 insertions(+), 10 deletions(-)']), ('several files', [[['p', 1, 0], ['q', 0, 1], ['r', 2, 2]], 5], ['p | 1 +', 'q | 1 -', 'r | 4 ++--', '3 files changed, 3 insertions(+), 3 deletions(-)']), ('unscaled wide change', [[['w', 12, 3]], 15], ['w | 15 ++++++++++++---', '1 file changed, 12 insertions(+), 3 deletions(-)']), ('floor not rounding when scaling', [[['r', 7, 0], ['s', 20, 0]], 10], ['r | 7 +++', 's | 20 ++++++++++', '2 files changed, 27 insertions(+)']), ('binary-only change', [[['img2.png', None, None]], 40], ['img2.png | Bin', '1 file changed'])],
    3: [('small changes without scaling', [[['a.txt', 3, 1]], 40], ['a.txt | 4 +++-', '1 file changed, 3 insertions(+), 1 deletion(-)']), ('scaled bar keeps small counts visible', [[['big.c', 200, 0], ['tiny.c', 1, 1]], 20], ['big.c | 200 ++++++++++++++++++++', 'tiny.c | 2 +-', '2 files changed, 201 insertions(+), 1 deletion(-)']), ('binary file', [[['logo.png', None, None], ['x', 2, 0]], 40], ['logo.png | Bin', 'x | 2 ++', '2 files changed, 2 insertions(+)']), ('single insertion grammar', [[['one', 1, 0]], 40], ['one | 1 +', '1 file changed, 1 insertion(+)']), ('only deletions', [[['gone', 0, 7]], 40], ['gone | 7 -------', '1 file changed, 7 deletions(-)']), ('scale uses the largest file', [[['f1', 30, 10], ['f2', 30, 0]], 10], ['f1 | 40 +++++++--', 'f2 | 30 +++++++', '2 files changed, 60 insertions(+), 10 deletions(-)']), ('several files', [[['p', 1, 0], ['q', 0, 1], ['r', 3, 3]], 5], ['p | 1 +', 'q | 1 -', 'r | 6 ++--', '3 files changed, 4 insertions(+), 4 deletions(-)']), ('unscaled wide change', [[['w', 12, 3]], 15], ['w | 15 ++++++++++++---', '1 file changed, 12 insertions(+), 3 deletions(-)']), ('floor not rounding when scaling', [[['r', 7, 0], ['s', 20, 0]], 10], ['r | 7 +++', 's | 20 ++++++++++', '2 files changed, 27 insertions(+)']), ('binary-only change', [[['img3.png', None, None]], 40], ['img3.png | Bin', '1 file changed'])],
    4: [('small changes without scaling', [[['a.txt', 3, 1]], 40], ['a.txt | 4 +++-', '1 file changed, 3 insertions(+), 1 deletion(-)']), ('scaled bar keeps small counts visible', [[['big.c', 200, 0], ['tiny.c', 1, 1]], 20], ['big.c | 200 ++++++++++++++++++++', 'tiny.c | 2 +-', '2 files changed, 201 insertions(+), 1 deletion(-)']), ('binary file', [[['logo.png', None, None], ['x', 2, 0]], 40], ['logo.png | Bin', 'x | 2 ++', '2 files changed, 2 insertions(+)']), ('single insertion grammar', [[['one', 1, 0]], 40], ['one | 1 +', '1 file changed, 1 insertion(+)']), ('only deletions', [[['gone', 0, 8]], 40], ['gone | 8 --------', '1 file changed, 8 deletions(-)']), ('scale uses the largest file', [[['f1', 30, 10], ['f2', 40, 0]], 10], ['f1 | 40 +++++++--', 'f2 | 40 ++++++++++', '2 files changed, 70 insertions(+), 10 deletions(-)']), ('several files', [[['p', 1, 0], ['q', 0, 1], ['r', 4, 4]], 5], ['p | 1 +', 'q | 1 -', 'r | 8 ++--', '3 files changed, 5 insertions(+), 5 deletions(-)']), ('unscaled wide change', [[['w', 12, 3]], 15], ['w | 15 ++++++++++++---', '1 file changed, 12 insertions(+), 3 deletions(-)']), ('floor not rounding when scaling', [[['r', 7, 0], ['s', 20, 0]], 10], ['r | 7 +++', 's | 20 ++++++++++', '2 files changed, 27 insertions(+)']), ('binary-only change', [[['img4.png', None, None]], 40], ['img4.png | Bin', '1 file changed'])],
    5: [('small changes without scaling', [[['a.txt', 3, 1]], 40], ['a.txt | 4 +++-', '1 file changed, 3 insertions(+), 1 deletion(-)']), ('scaled bar keeps small counts visible', [[['big.c', 200, 0], ['tiny.c', 1, 1]], 20], ['big.c | 200 ++++++++++++++++++++', 'tiny.c | 2 +-', '2 files changed, 201 insertions(+), 1 deletion(-)']), ('binary file', [[['logo.png', None, None], ['x', 2, 0]], 40], ['logo.png | Bin', 'x | 2 ++', '2 files changed, 2 insertions(+)']), ('single insertion grammar', [[['one', 1, 0]], 40], ['one | 1 +', '1 file changed, 1 insertion(+)']), ('only deletions', [[['gone', 0, 9]], 40], ['gone | 9 ---------', '1 file changed, 9 deletions(-)']), ('scale uses the largest file', [[['f1', 30, 10], ['f2', 50, 0]], 10], ['f1 | 40 ++++++--', 'f2 | 50 ++++++++++', '2 files changed, 80 insertions(+), 10 deletions(-)']), ('several files', [[['p', 1, 0], ['q', 0, 1], ['r', 5, 5]], 5], ['p | 1 +', 'q | 1 -', 'r | 10 ++--', '3 files changed, 6 insertions(+), 6 deletions(-)']), ('unscaled wide change', [[['w', 12, 3]], 15], ['w | 15 ++++++++++++---', '1 file changed, 12 insertions(+), 3 deletions(-)']), ('floor not rounding when scaling', [[['r', 7, 0], ['s', 20, 0]], 10], ['r | 7 +++', 's | 20 ++++++++++', '2 files changed, 27 insertions(+)']), ('binary-only change', [[['img5.png', None, None]], 40], ['img5.png | Bin', '1 file changed'])],
}[N]
for label, args, expected in cases:
    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
small changes without scaling	`['a.txt \| 4 +++-', '1 file changed, 3 insertions(+), 1 deletion(-)']`	`['a.txt \| 4 +++-', '1 file changed, 3 insertions(+), 1 deletion(-)']`	Passed
scaled bar keeps small counts visible	`['big.c \| 200 ++++++++++++++++++++', 'tiny.c \| 2 ', '2 files changed, 201 insertions(+), 1 deletion(-)']`	`['big.c \| 200 ++++++++++++++++++++', 'tiny.c \| 2 +-', '2 files changed, 201 insertions(+), 1 deletion(-)']`	Failed
binary file	`['logo.png \| Bin', 'x \| 2 ++', '2 files changed, 2 insertions(+)']`	`['logo.png \| Bin', 'x \| 2 ++', '2 files changed, 2 insertions(+)']`	Passed
single insertion grammar	`['one \| 1 +', '1 file changed, 1 insertion(+)']`	`['one \| 1 +', '1 file changed, 1 insertion(+)']`	Passed
only deletions	`['gone \| 5 -----', '1 file changed, 5 deletions(-)']`	`['gone \| 5 -----', '1 file changed, 5 deletions(-)']`	Passed
scale uses the largest file	`['f1 \| 40 +++++++--', 'f2 \| 10 ++', '2 files changed, 40 insertions(+), 10 deletions(-)']`	`['f1 \| 40 +++++++--', 'f2 \| 10 ++', '2 files changed, 40 insertions(+), 10 deletions(-)']`	Passed
several files	`['p \| 1 +', 'q \| 1 -', 'r \| 2 +-', '3 files changed, 2 insertions(+), 2 deletions(-)']`	`['p \| 1 +', 'q \| 1 -', 'r \| 2 +-', '3 files changed, 2 insertions(+), 2 deletions(-)']`	Passed
unscaled wide change	`['w \| 15 ++++++++++++---', '1 file changed, 12 insertions(+), 3 deletions(-)']`	`['w \| 15 ++++++++++++---', '1 file changed, 12 insertions(+), 3 deletions(-)']`	Passed
floor not rounding when scaling	`['r \| 7 +++', 's \| 20 ++++++++++', '2 files changed, 27 insertions(+)']`	`['r \| 7 +++', 's \| 20 ++++++++++', '2 files changed, 27 insertions(+)']`	Passed
binary-only change	`['img1.png \| Bin', '1 file changed']`	`['img1.png \| Bin', '1 file changed']`	Passed

SHA-256 / d77a9c07bc6c07f88a5386ee50dbde9e1990262c88c6a2d0534ee758b67e40be

2 / The unsuccessful fix

Exit 1

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

N = 1
observations = []
def solve(files, width):
    mx = max([f[1] + f[2] for f in files if f[1] is not None] + [0])
    lines = []
    ins = dels = changed = 0
    for path, add, rem in files:
        changed += 1
        if add is None:
            lines.append('%s | Bin' % path)
            continue
        ins += add
        dels += rem
        if mx > width:
            pa = add * width // mx
            pr = rem * width // mx
            if not pa:
                pa = 1
            if not pr:
                pr = 1
        else:
            pa, pr = add, rem
        lines.append('%s | %d %s' % (path, add + rem, '+' * pa + '-' * pr))
    summary = '%d file%s changed' % (changed, '' if changed == 1 else 's')
    if ins:
        summary += ', %d insertion%s(+)' % (ins, '' if ins == 1 else 's')
    if dels:
        summary += ', %d deletion%s(-)' % (dels, '' if dels == 1 else 's')
    lines.append(summary)
    return lines
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
cases = {
    1: [('small changes without scaling', [[['a.txt', 3, 1]], 40], ['a.txt | 4 +++-', '1 file changed, 3 insertions(+), 1 deletion(-)']), ('scaled bar keeps small counts visible', [[['big.c', 200, 0], ['tiny.c', 1, 1]], 20], ['big.c | 200 ++++++++++++++++++++', 'tiny.c | 2 +-', '2 files changed, 201 insertions(+), 1 deletion(-)']), ('binary file', [[['logo.png', None, None], ['x', 2, 0]], 40], ['logo.png | Bin', 'x | 2 ++', '2 files changed, 2 insertions(+)']), ('single insertion grammar', [[['one', 1, 0]], 40], ['one | 1 +', '1 file changed, 1 insertion(+)']), ('only deletions', [[['gone', 0, 5]], 40], ['gone | 5 -----', '1 file changed, 5 deletions(-)']), ('scale uses the largest file', [[['f1', 30, 10], ['f2', 10, 0]], 10], ['f1 | 40 +++++++--', 'f2 | 10 ++', '2 files changed, 40 insertions(+), 10 deletions(-)']), ('several files', [[['p', 1, 0], ['q', 0, 1], ['r', 1, 1]], 5], ['p | 1 +', 'q | 1 -', 'r | 2 +-', '3 files changed, 2 insertions(+), 2 deletions(-)']), ('unscaled wide change', [[['w', 12, 3]], 15], ['w | 15 ++++++++++++---', '1 file changed, 12 insertions(+), 3 deletions(-)']), ('floor not rounding when scaling', [[['r', 7, 0], ['s', 20, 0]], 10], ['r | 7 +++', 's | 20 ++++++++++', '2 files changed, 27 insertions(+)']), ('binary-only change', [[['img1.png', None, None]], 40], ['img1.png | Bin', '1 file changed'])],
    2: [('small changes without scaling', [[['a.txt', 3, 1]], 40], ['a.txt | 4 +++-', '1 file changed, 3 insertions(+), 1 deletion(-)']), ('scaled bar keeps small counts visible', [[['big.c', 200, 0], ['tiny.c', 1, 1]], 20], ['big.c | 200 ++++++++++++++++++++', 'tiny.c | 2 +-', '2 files changed, 201 insertions(+), 1 deletion(-)']), ('binary file', [[['logo.png', None, None], ['x', 2, 0]], 40], ['logo.png | Bin', 'x | 2 ++', '2 files changed, 2 insertions(+)']), ('single insertion grammar', [[['one', 1, 0]], 40], ['one | 1 +', '1 file changed, 1 insertion(+)']), ('only deletions', [[['gone', 0, 6]], 40], ['gone | 6 ------', '1 file changed, 6 deletions(-)']), ('scale uses the largest file', [[['f1', 30, 10], ['f2', 20, 0]], 10], ['f1 | 40 +++++++--', 'f2 | 20 +++++', '2 files changed, 50 insertions(+), 10 deletions(-)']), ('several files', [[['p', 1, 0], ['q', 0, 1], ['r', 2, 2]], 5], ['p | 1 +', 'q | 1 -', 'r | 4 ++--', '3 files changed, 3 insertions(+), 3 deletions(-)']), ('unscaled wide change', [[['w', 12, 3]], 15], ['w | 15 ++++++++++++---', '1 file changed, 12 insertions(+), 3 deletions(-)']), ('floor not rounding when scaling', [[['r', 7, 0], ['s', 20, 0]], 10], ['r | 7 +++', 's | 20 ++++++++++', '2 files changed, 27 insertions(+)']), ('binary-only change', [[['img2.png', None, None]], 40], ['img2.png | Bin', '1 file changed'])],
    3: [('small changes without scaling', [[['a.txt', 3, 1]], 40], ['a.txt | 4 +++-', '1 file changed, 3 insertions(+), 1 deletion(-)']), ('scaled bar keeps small counts visible', [[['big.c', 200, 0], ['tiny.c', 1, 1]], 20], ['big.c | 200 ++++++++++++++++++++', 'tiny.c | 2 +-', '2 files changed, 201 insertions(+), 1 deletion(-)']), ('binary file', [[['logo.png', None, None], ['x', 2, 0]], 40], ['logo.png | Bin', 'x | 2 ++', '2 files changed, 2 insertions(+)']), ('single insertion grammar', [[['one', 1, 0]], 40], ['one | 1 +', '1 file changed, 1 insertion(+)']), ('only deletions', [[['gone', 0, 7]], 40], ['gone | 7 -------', '1 file changed, 7 deletions(-)']), ('scale uses the largest file', [[['f1', 30, 10], ['f2', 30, 0]], 10], ['f1 | 40 +++++++--', 'f2 | 30 +++++++', '2 files changed, 60 insertions(+), 10 deletions(-)']), ('several files', [[['p', 1, 0], ['q', 0, 1], ['r', 3, 3]], 5], ['p | 1 +', 'q | 1 -', 'r | 6 ++--', '3 files changed, 4 insertions(+), 4 deletions(-)']), ('unscaled wide change', [[['w', 12, 3]], 15], ['w | 15 ++++++++++++---', '1 file changed, 12 insertions(+), 3 deletions(-)']), ('floor not rounding when scaling', [[['r', 7, 0], ['s', 20, 0]], 10], ['r | 7 +++', 's | 20 ++++++++++', '2 files changed, 27 insertions(+)']), ('binary-only change', [[['img3.png', None, None]], 40], ['img3.png | Bin', '1 file changed'])],
    4: [('small changes without scaling', [[['a.txt', 3, 1]], 40], ['a.txt | 4 +++-', '1 file changed, 3 insertions(+), 1 deletion(-)']), ('scaled bar keeps small counts visible', [[['big.c', 200, 0], ['tiny.c', 1, 1]], 20], ['big.c | 200 ++++++++++++++++++++', 'tiny.c | 2 +-', '2 files changed, 201 insertions(+), 1 deletion(-)']), ('binary file', [[['logo.png', None, None], ['x', 2, 0]], 40], ['logo.png | Bin', 'x | 2 ++', '2 files changed, 2 insertions(+)']), ('single insertion grammar', [[['one', 1, 0]], 40], ['one | 1 +', '1 file changed, 1 insertion(+)']), ('only deletions', [[['gone', 0, 8]], 40], ['gone | 8 --------', '1 file changed, 8 deletions(-)']), ('scale uses the largest file', [[['f1', 30, 10], ['f2', 40, 0]], 10], ['f1 | 40 +++++++--', 'f2 | 40 ++++++++++', '2 files changed, 70 insertions(+), 10 deletions(-)']), ('several files', [[['p', 1, 0], ['q', 0, 1], ['r', 4, 4]], 5], ['p | 1 +', 'q | 1 -', 'r | 8 ++--', '3 files changed, 5 insertions(+), 5 deletions(-)']), ('unscaled wide change', [[['w', 12, 3]], 15], ['w | 15 ++++++++++++---', '1 file changed, 12 insertions(+), 3 deletions(-)']), ('floor not rounding when scaling', [[['r', 7, 0], ['s', 20, 0]], 10], ['r | 7 +++', 's | 20 ++++++++++', '2 files changed, 27 insertions(+)']), ('binary-only change', [[['img4.png', None, None]], 40], ['img4.png | Bin', '1 file changed'])],
    5: [('small changes without scaling', [[['a.txt', 3, 1]], 40], ['a.txt | 4 +++-', '1 file changed, 3 insertions(+), 1 deletion(-)']), ('scaled bar keeps small counts visible', [[['big.c', 200, 0], ['tiny.c', 1, 1]], 20], ['big.c | 200 ++++++++++++++++++++', 'tiny.c | 2 +-', '2 files changed, 201 insertions(+), 1 deletion(-)']), ('binary file', [[['logo.png', None, None], ['x', 2, 0]], 40], ['logo.png | Bin', 'x | 2 ++', '2 files changed, 2 insertions(+)']), ('single insertion grammar', [[['one', 1, 0]], 40], ['one | 1 +', '1 file changed, 1 insertion(+)']), ('only deletions', [[['gone', 0, 9]], 40], ['gone | 9 ---------', '1 file changed, 9 deletions(-)']), ('scale uses the largest file', [[['f1', 30, 10], ['f2', 50, 0]], 10], ['f1 | 40 ++++++--', 'f2 | 50 ++++++++++', '2 files changed, 80 insertions(+), 10 deletions(-)']), ('several files', [[['p', 1, 0], ['q', 0, 1], ['r', 5, 5]], 5], ['p | 1 +', 'q | 1 -', 'r | 10 ++--', '3 files changed, 6 insertions(+), 6 deletions(-)']), ('unscaled wide change', [[['w', 12, 3]], 15], ['w | 15 ++++++++++++---', '1 file changed, 12 insertions(+), 3 deletions(-)']), ('floor not rounding when scaling', [[['r', 7, 0], ['s', 20, 0]], 10], ['r | 7 +++', 's | 20 ++++++++++', '2 files changed, 27 insertions(+)']), ('binary-only change', [[['img5.png', None, None]], 40], ['img5.png | Bin', '1 file changed'])],
}[N]
for label, args, expected in cases:
    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
small changes without scaling	`['a.txt \| 4 +++-', '1 file changed, 3 insertions(+), 1 deletion(-)']`	`['a.txt \| 4 +++-', '1 file changed, 3 insertions(+), 1 deletion(-)']`	Passed
scaled bar keeps small counts visible	`['big.c \| 200 ++++++++++++++++++++-', 'tiny.c \| 2 +-', '2 files changed, 201 insertions(+), 1 deletion(-)']`	`['big.c \| 200 ++++++++++++++++++++', 'tiny.c \| 2 +-', '2 files changed, 201 insertions(+), 1 deletion(-)']`	Failed
binary file	`['logo.png \| Bin', 'x \| 2 ++', '2 files changed, 2 insertions(+)']`	`['logo.png \| Bin', 'x \| 2 ++', '2 files changed, 2 insertions(+)']`	Passed
single insertion grammar	`['one \| 1 +', '1 file changed, 1 insertion(+)']`	`['one \| 1 +', '1 file changed, 1 insertion(+)']`	Passed
only deletions	`['gone \| 5 -----', '1 file changed, 5 deletions(-)']`	`['gone \| 5 -----', '1 file changed, 5 deletions(-)']`	Passed
scale uses the largest file	`['f1 \| 40 +++++++--', 'f2 \| 10 ++-', '2 files changed, 40 insertions(+), 10 deletions(-)']`	`['f1 \| 40 +++++++--', 'f2 \| 10 ++', '2 files changed, 40 insertions(+), 10 deletions(-)']`	Failed
several files	`['p \| 1 +', 'q \| 1 -', 'r \| 2 +-', '3 files changed, 2 insertions(+), 2 deletions(-)']`	`['p \| 1 +', 'q \| 1 -', 'r \| 2 +-', '3 files changed, 2 insertions(+), 2 deletions(-)']`	Passed
unscaled wide change	`['w \| 15 ++++++++++++---', '1 file changed, 12 insertions(+), 3 deletions(-)']`	`['w \| 15 ++++++++++++---', '1 file changed, 12 insertions(+), 3 deletions(-)']`	Passed
floor not rounding when scaling	`['r \| 7 +++-', 's \| 20 ++++++++++-', '2 files changed, 27 insertions(+)']`	`['r \| 7 +++', 's \| 20 ++++++++++', '2 files changed, 27 insertions(+)']`	Failed
binary-only change	`['img1.png \| Bin', '1 file changed']`	`['img1.png \| Bin', '1 file changed']`	Passed

SHA-256 / 2466dd48ab31df57ed6184382603ccbf8ceed0cfb44c69f0b1a5243c37f41dbd

HELD IN THE MEMBER ARCHIVE

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

This mechanism has 10 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.

Verification & scope

A deterministic, bounded teaching model of one diff, patch or merge rule with stipulated conventions; it is not a production diff or version-control implementation and makes no claim of conformance to any specific tool. 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 2026-09-29T14:49:07.434775+00:00.

Case digest / a03654826f5669e3b4b8ce9b057ad86647cc901304cb4c64689a1fac9525c995