FAILURE MAP
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FA-79316 / Image orientation metadata / Open access

Sidecar loses to the file when both were saved in the same second · case 01

Rotations made in the manager revert after an export that touched both files within one second.

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

ROOT CAUSE

Equal timestamps favour the embedded value instead of the sidecar.

THE FAILURE

Equal timestamps favour the embedded value instead of the sidecar.

Unsuccessful approach: Requiring a margin of more than a second makes the sidecar lose even more often.

Case contract

A photo manager reconciles the embedded orientation with an XMP sidecar. Values are valid if they are integers 1..8 or strings that are exactly one digit 1..8 after trimming. Policy "sidecar" prefers the sidecar, "embedded" prefers the file, and "newest" (also used for unknown policies) prefers the sidecar when both are valid and sidecar_mtime >= file_mtime; the other valid value is the fallback, then 1.

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(d):
    def ok(v):
        if isinstance(v, str) and v.strip() in ('1', '2', '3', '4', '5', '6', '7', '8'):
            return int(v.strip())
        if isinstance(v, int) and not isinstance(v, bool) and 1 <= v <= 8:
            return v
        return None
    e = ok(d.get('embedded'))
    s = ok(d.get('sidecar'))
    pol = d.get('policy')
    if pol not in ('newest', 'sidecar', 'embedded'):
        pol = 'newest'
    if pol == 'sidecar':
        order = [s, e]
    elif pol == 'embedded':
        order = [e, s]
    elif s is not None and e is not None:
        order = [s, e] if d['sidecar_mtime'] > d['file_mtime'] else [e, s]
    else:
        order = [s, e]
    for v in order:
        if v is not None:
            return v
    return 1
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[[{'embedded': ' 8', 'sidecar': 5, 'file_mtime': 105, 'sidecar_mtime': 105, 'policy': 'newest'}, 5], [{'embedded': 3, 'sidecar': ' 8', 'file_mtime': 105, 'sidecar_mtime': 105, 'policy': 'latest'}, 8], [{'embedded': 5, 'sidecar': '+3', 'file_mtime': 103, 'sidecar_mtime': 108, 'policy': 'newest'}, 5], [{'embedded': 'x', 'sidecar': 'x', 'file_mtime': 109, 'sidecar_mtime': 109, 'policy': 'embedded'}, 1], [{'embedded': 8, 'sidecar': 'x', 'file_mtime': 102, 'sidecar_mtime': 101, 'policy': 'newest'}, 8], [{'embedded': 9, 'sidecar': 9, 'file_mtime': 108, 'sidecar_mtime': 109, 'policy': None}, 1], [{'embedded': '06', 'sidecar': None, 'file_mtime': 101, 'sidecar_mtime': 100, 'policy': 'embedded'}, 1], [{'embedded': '6', 'sidecar': 5, 'file_mtime': 101, 'sidecar_mtime': 101, 'policy': None}, 5]], [[{'embedded': ' 8', 'sidecar': 5, 'file_mtime': 101, 'sidecar_mtime': 101, 'policy': None}, 5], [{'embedded': 5, 'sidecar': ' 8', 'file_mtime': 104, 'sidecar_mtime': 105, 'policy': 'newest'}, 8], [{'embedded': 3, 'sidecar': None, 'file_mtime': 106, 'sidecar_mtime': 106, 'policy': 'embedded'}, 3], [{'embedded': 1, 'sidecar': '06', 'file_mtime': 104, 'sidecar_mtime': 105, 'policy': 'sidecar'}, 1], [{'embedded': ' 8', 'sidecar': 8, 'file_mtime': 107, 'sidecar_mtime': 112, 'policy': 'embedded'}, 8], [{'embedded': 3, 'sidecar': 6, 'file_mtime': 101, 'sidecar_mtime': 96, 'policy': 'sidecar'}, 6], [{'embedded': 3, 'sidecar': 'x', 'file_mtime': 102, 'sidecar_mtime': 103, 'policy': 'newest'}, 3], [{'embedded': 3, 'sidecar': 8, 'file_mtime': 106, 'sidecar_mtime': 106, 'policy': 'latest'}, 8]], [[{'embedded': ' 8', 'sidecar': 3, 'file_mtime': 105, 'sidecar_mtime': 105, 'policy': None}, 3], [{'embedded': 8, 'sidecar': '6', 'file_mtime': 102, 'sidecar_mtime': 102, 'policy': None}, 6], [{'embedded': None, 'sidecar': '06', 'file_mtime': 110, 'sidecar_mtime': 115, 'policy': 'newest'}, 1], [{'embedded': 3, 'sidecar': '+3', 'file_mtime': 109, 'sidecar_mtime': 114, 'policy': None}, 3], [{'embedded': 'x', 'sidecar': ' 8', 'file_mtime': 101, 'sidecar_mtime': 101, 'policy': 'sidecar'}, 8], [{'embedded': 5, 'sidecar': 9, 'file_mtime': 105, 'sidecar_mtime': 110, 'policy': 'latest'}, 5], [{'embedded': ' 8', 'sidecar': '06', 'file_mtime': 100, 'sidecar_mtime': 101, 'policy': 'newest'}, 8], [{'embedded': 8, 'sidecar': 1, 'file_mtime': 108, 'sidecar_mtime': 108, 'policy': None}, 1]], [[{'embedded': 6, 'sidecar': ' 8', 'file_mtime': 106, 'sidecar_mtime': 106, 'policy': 'newest'}, 8], [{'embedded': 1, 'sidecar': ' 8', 'file_mtime': 105, 'sidecar_mtime': 106, 'policy': 'newest'}, 8], [{'embedded': ' 8', 'sidecar': '6', 'file_mtime': 102, 'sidecar_mtime': 102, 'policy': None}, 6], [{'embedded': 1, 'sidecar': '6', 'file_mtime': 100, 'sidecar_mtime': 99, 'policy': 'newest'}, 1], [{'embedded': 6, 'sidecar': 6, 'file_mtime': 100, 'sidecar_mtime': 105, 'policy': 'sidecar'}, 6], [{'embedded': 5, 'sidecar': 8, 'file_mtime': 109, 'sidecar_mtime': 114, 'policy': 'newest'}, 8], [{'embedded': None, 'sidecar': '6', 'file_mtime': 104, 'sidecar_mtime': 104, 'policy': 'latest'}, 6], [{'embedded': 8, 'sidecar': 3, 'file_mtime': 107, 'sidecar_mtime': 107, 'policy': None}, 3]], [[{'embedded': '6', 'sidecar': 8, 'file_mtime': 106, 'sidecar_mtime': 106, 'policy': 'newest'}, 8], [{'embedded': 1, 'sidecar': 5, 'file_mtime': 107, 'sidecar_mtime': 108, 'policy': None}, 5], [{'embedded': 5, 'sidecar': '6', 'file_mtime': 105, 'sidecar_mtime': 105, 'policy': 'latest'}, 6], [{'embedded': ' 8', 'sidecar': 8, 'file_mtime': 110, 'sidecar_mtime': 110, 'policy': 'embedded'}, 8], [{'embedded': 0, 'sidecar': 'x', 'file_mtime': 102, 'sidecar_mtime': 102, 'policy': 'embedded'}, 1], [{'embedded': 0, 'sidecar': 9, 'file_mtime': 100, 'sidecar_mtime': 99, 'policy': 'latest'}, 1], [{'embedded': ' 8', 'sidecar': 0, 'file_mtime': 100, 'sidecar_mtime': 100, 'policy': None}, 8], [{'embedded': 6, 'sidecar': 8, 'file_mtime': 103, 'sidecar_mtime': 103, 'policy': 'latest'}, 8]]]
labels = ["regression: equal modification times", "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 fixtureActualExpectedOutcome
regression: equal modification times 085Failed
repair trap 138Failed
combined fault 255Passed
control 311Passed
control 488Passed
boundary 511Passed
boundary 611Passed
control 765Failed

SHA-256 / 5a8938a722d2384e11da5d62cd913d4f282ac8de285628b014b73a68a6015e01

2 / The unsuccessful fix

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

N = 1
observations = []
def solve(d):
    def ok(v):
        if isinstance(v, str) and v.strip() in ('1', '2', '3', '4', '5', '6', '7', '8'):
            return int(v.strip())
        if isinstance(v, int) and not isinstance(v, bool) and 1 <= v <= 8:
            return v
        return None
    e = ok(d.get('embedded'))
    s = ok(d.get('sidecar'))
    pol = d.get('policy')
    if pol not in ('newest', 'sidecar', 'embedded'):
        pol = 'newest'
    if pol == 'sidecar':
        order = [s, e]
    elif pol == 'embedded':
        order = [e, s]
    elif s is not None and e is not None:
        order = [s, e] if d['sidecar_mtime'] - d['file_mtime'] > 1 else [e, s]
    else:
        order = [s, e]
    for v in order:
        if v is not None:
            return v
    return 1
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[[{'embedded': ' 8', 'sidecar': 5, 'file_mtime': 105, 'sidecar_mtime': 105, 'policy': 'newest'}, 5], [{'embedded': 3, 'sidecar': ' 8', 'file_mtime': 105, 'sidecar_mtime': 105, 'policy': 'latest'}, 8], [{'embedded': 5, 'sidecar': '+3', 'file_mtime': 103, 'sidecar_mtime': 108, 'policy': 'newest'}, 5], [{'embedded': 'x', 'sidecar': 'x', 'file_mtime': 109, 'sidecar_mtime': 109, 'policy': 'embedded'}, 1], [{'embedded': 8, 'sidecar': 'x', 'file_mtime': 102, 'sidecar_mtime': 101, 'policy': 'newest'}, 8], [{'embedded': 9, 'sidecar': 9, 'file_mtime': 108, 'sidecar_mtime': 109, 'policy': None}, 1], [{'embedded': '06', 'sidecar': None, 'file_mtime': 101, 'sidecar_mtime': 100, 'policy': 'embedded'}, 1], [{'embedded': '6', 'sidecar': 5, 'file_mtime': 101, 'sidecar_mtime': 101, 'policy': None}, 5]], [[{'embedded': ' 8', 'sidecar': 5, 'file_mtime': 101, 'sidecar_mtime': 101, 'policy': None}, 5], [{'embedded': 5, 'sidecar': ' 8', 'file_mtime': 104, 'sidecar_mtime': 105, 'policy': 'newest'}, 8], [{'embedded': 3, 'sidecar': None, 'file_mtime': 106, 'sidecar_mtime': 106, 'policy': 'embedded'}, 3], [{'embedded': 1, 'sidecar': '06', 'file_mtime': 104, 'sidecar_mtime': 105, 'policy': 'sidecar'}, 1], [{'embedded': ' 8', 'sidecar': 8, 'file_mtime': 107, 'sidecar_mtime': 112, 'policy': 'embedded'}, 8], [{'embedded': 3, 'sidecar': 6, 'file_mtime': 101, 'sidecar_mtime': 96, 'policy': 'sidecar'}, 6], [{'embedded': 3, 'sidecar': 'x', 'file_mtime': 102, 'sidecar_mtime': 103, 'policy': 'newest'}, 3], [{'embedded': 3, 'sidecar': 8, 'file_mtime': 106, 'sidecar_mtime': 106, 'policy': 'latest'}, 8]], [[{'embedded': ' 8', 'sidecar': 3, 'file_mtime': 105, 'sidecar_mtime': 105, 'policy': None}, 3], [{'embedded': 8, 'sidecar': '6', 'file_mtime': 102, 'sidecar_mtime': 102, 'policy': None}, 6], [{'embedded': None, 'sidecar': '06', 'file_mtime': 110, 'sidecar_mtime': 115, 'policy': 'newest'}, 1], [{'embedded': 3, 'sidecar': '+3', 'file_mtime': 109, 'sidecar_mtime': 114, 'policy': None}, 3], [{'embedded': 'x', 'sidecar': ' 8', 'file_mtime': 101, 'sidecar_mtime': 101, 'policy': 'sidecar'}, 8], [{'embedded': 5, 'sidecar': 9, 'file_mtime': 105, 'sidecar_mtime': 110, 'policy': 'latest'}, 5], [{'embedded': ' 8', 'sidecar': '06', 'file_mtime': 100, 'sidecar_mtime': 101, 'policy': 'newest'}, 8], [{'embedded': 8, 'sidecar': 1, 'file_mtime': 108, 'sidecar_mtime': 108, 'policy': None}, 1]], [[{'embedded': 6, 'sidecar': ' 8', 'file_mtime': 106, 'sidecar_mtime': 106, 'policy': 'newest'}, 8], [{'embedded': 1, 'sidecar': ' 8', 'file_mtime': 105, 'sidecar_mtime': 106, 'policy': 'newest'}, 8], [{'embedded': ' 8', 'sidecar': '6', 'file_mtime': 102, 'sidecar_mtime': 102, 'policy': None}, 6], [{'embedded': 1, 'sidecar': '6', 'file_mtime': 100, 'sidecar_mtime': 99, 'policy': 'newest'}, 1], [{'embedded': 6, 'sidecar': 6, 'file_mtime': 100, 'sidecar_mtime': 105, 'policy': 'sidecar'}, 6], [{'embedded': 5, 'sidecar': 8, 'file_mtime': 109, 'sidecar_mtime': 114, 'policy': 'newest'}, 8], [{'embedded': None, 'sidecar': '6', 'file_mtime': 104, 'sidecar_mtime': 104, 'policy': 'latest'}, 6], [{'embedded': 8, 'sidecar': 3, 'file_mtime': 107, 'sidecar_mtime': 107, 'policy': None}, 3]], [[{'embedded': '6', 'sidecar': 8, 'file_mtime': 106, 'sidecar_mtime': 106, 'policy': 'newest'}, 8], [{'embedded': 1, 'sidecar': 5, 'file_mtime': 107, 'sidecar_mtime': 108, 'policy': None}, 5], [{'embedded': 5, 'sidecar': '6', 'file_mtime': 105, 'sidecar_mtime': 105, 'policy': 'latest'}, 6], [{'embedded': ' 8', 'sidecar': 8, 'file_mtime': 110, 'sidecar_mtime': 110, 'policy': 'embedded'}, 8], [{'embedded': 0, 'sidecar': 'x', 'file_mtime': 102, 'sidecar_mtime': 102, 'policy': 'embedded'}, 1], [{'embedded': 0, 'sidecar': 9, 'file_mtime': 100, 'sidecar_mtime': 99, 'policy': 'latest'}, 1], [{'embedded': ' 8', 'sidecar': 0, 'file_mtime': 100, 'sidecar_mtime': 100, 'policy': None}, 8], [{'embedded': 6, 'sidecar': 8, 'file_mtime': 103, 'sidecar_mtime': 103, 'policy': 'latest'}, 8]]]
labels = ["regression: equal modification times", "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 fixtureActualExpectedOutcome
regression: equal modification times 085Failed
repair trap 138Failed
combined fault 255Passed
control 311Passed
control 488Passed
boundary 511Passed
boundary 611Passed
control 765Failed

SHA-256 / 483e6f2243891aac299d3a6c9639ef4676cb65c62bac926aa622cea26f5be715

HELD IN THE MEMBER ARCHIVE

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

This mechanism has 8 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.

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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 2026-09-29T14:49:43.432503+00:00.

Case digest / 0edb3347725bf4f75144c82c41ed6030026d1b0b1e1af64ca62f9550817b4cd9