FAILURE MAP
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FA-11046 / Media playlist state / Open access

Reorder preserves entry identity · case 01

A reorder preserves the old numeric selection rather than the selected entry.

Verified by executionVariant 1 · 4 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

A reorder preserves the old numeric selection rather than the selected entry.

THE FAILURE

A reorder preserves the old numeric selection rather than the selected entry.

Unsuccessful approach: Resetting to the first entry changes playback when current is elsewhere.

Case contract

Order is a permutation of all original indices; update playlist order and selection so the same entry keeps playing.

Why this case matters

A deterministic local media controller stage; metadata and downloaded data are supplied explicitly. No external player, service or codec is required.

1 / The failure

Exit 1
"""Failure Map reference implementation. Python standard library only."""
import json
import math
N = 1
observations = []
def solve(entries, current, order):
    return [[entries[i] for i in order],current]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('fixture 1',solve(*(['a', 'b', 'c'], 0, [2, 0, 1])),[['c', 'a', 'b'], 1])
check('fixture 2',solve(*(['a', 'b', 'c'], 2, [2, 0, 1])),[['c', 'a', 'b'], 0])
check('fixture 3',solve(*(['a', 'b'], 1, [0, 1])),[['a', 'b'], 1])
check('fixture 4',solve(*(['a'], 0, [0])),[['a'], 0])
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
fixture 1[['c', 'a', 'b'], 0][['c', 'a', 'b'], 1]Failed
fixture 2[['c', 'a', 'b'], 2][['c', 'a', 'b'], 0]Failed
fixture 3[['a', 'b'], 1][['a', 'b'], 1]Passed
fixture 4[['a'], 0][['a'], 0]Passed

SHA-256 / a6506c86b740a23a62975c83613738f72b8345b0026b032aee51e1a4a5c07ef1

2 / The unsuccessful fix

Exit 1
"""Failure Map reference implementation. Python standard library only."""
import json
import math
N = 1
observations = []
def solve(entries, current, order):
    return [[entries[i] for i in order],0]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('fixture 1',solve(*(['a', 'b', 'c'], 0, [2, 0, 1])),[['c', 'a', 'b'], 1])
check('fixture 2',solve(*(['a', 'b', 'c'], 2, [2, 0, 1])),[['c', 'a', 'b'], 0])
check('fixture 3',solve(*(['a', 'b'], 1, [0, 1])),[['a', 'b'], 1])
check('fixture 4',solve(*(['a'], 0, [0])),[['a'], 0])
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
fixture 1[['c', 'a', 'b'], 0][['c', 'a', 'b'], 1]Failed
fixture 2[['c', 'a', 'b'], 0][['c', 'a', 'b'], 0]Passed
fixture 3[['a', 'b'], 0][['a', 'b'], 1]Failed
fixture 4[['a'], 0][['a'], 0]Passed

SHA-256 / 2bf30d802780c06446cda1a8370efc499e02a82a05433809d3aa1ab82dc58e0a

HELD IN THE MEMBER ARCHIVE

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

This mechanism has 4 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

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 2026-09-29T14:38:44.424200+00:00.

Case digest / 1d1b94ebf4a5fd4cfd93e8c2a72f44682046be10e66a4fd322626cba50cc7140