FA-11051 / Media playlist state / Open access
Duplicate track removal by entry id · case 01
Removing a track occurrence deletes every playlist occurrence of that track.
ROOT CAUSE
Removing a track occurrence deletes every playlist occurrence of that track.
VERIFIED REPAIR
Preserve the media contract: Entries are [unique entry-ID,track-ID]. Remove exactly the selected entry identity, retaining other appearances of the same track.
Unsuccessful approach: Keeping only the targeted identity reverses the removal predicate.
Case contract
Entries are [unique entry-ID,track-ID]. Remove exactly the selected entry identity, retaining other appearances of the same track.
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, identity):
return [x for x in entries if x[1]!=next((y[1] for y in entries if y[0]==identity),None)]
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('fixture 1',solve(*([['e1', 'song'], ['e2', 'song'], ['e3', 'other']], 'e1')),[['e2', 'song'], ['e3', 'other']])
check('fixture 2',solve(*([], 'x')),[])
check('fixture 3',solve(*([['a', 'song']], 'x')),[['a', 'song']])
check('fixture 4',solve(*([['a', 'song']], 'a')),[])
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 |
|---|---|---|---|
| fixture 1 | [['e3', 'other']] | [['e2', 'song'], ['e3', 'other']] | Failed |
| fixture 2 | [] | [] | Passed |
| fixture 3 | [['a', 'song']] | [['a', 'song']] | Passed |
| fixture 4 | [] | [] | Passed |
SHA-256 / f34a471dbf507cdd2f0fa957f2539d343a2079372e1156a80346702bb18bbef7
2 / The unsuccessful fix
Exit 1"""Failure Map reference implementation. Python standard library only."""
import json
import math
N = 1
observations = []
def solve(entries, identity):
return [x for x in entries if x[0]==identity]
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('fixture 1',solve(*([['e1', 'song'], ['e2', 'song'], ['e3', 'other']], 'e1')),[['e2', 'song'], ['e3', 'other']])
check('fixture 2',solve(*([], 'x')),[])
check('fixture 3',solve(*([['a', 'song']], 'x')),[['a', 'song']])
check('fixture 4',solve(*([['a', 'song']], 'a')),[])
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 |
|---|---|---|---|
| fixture 1 | [['e1', 'song']] | [['e2', 'song'], ['e3', 'other']] | Failed |
| fixture 2 | [] | [] | Passed |
| fixture 3 | [] | [['a', 'song']] | Failed |
| fixture 4 | [['a', 'song']] | [] | Failed |
SHA-256 / 6caa4d57a79a7cf4e54aae63e36ff053fb17d28420760a0c648df4c05df7137e
3 / The verified repair
Exit 0"""Failure Map reference implementation. Python standard library only."""
import json
import math
N = 1
observations = []
def solve(entries, identity):
return [x for x in entries if x[0]!=identity]
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('fixture 1',solve(*([['e1', 'song'], ['e2', 'song'], ['e3', 'other']], 'e1')),[['e2', 'song'], ['e3', 'other']])
check('fixture 2',solve(*([], 'x')),[])
check('fixture 3',solve(*([['a', 'song']], 'x')),[['a', 'song']])
check('fixture 4',solve(*([['a', 'song']], 'a')),[])
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 |
|---|---|---|---|
| fixture 1 | [['e2', 'song'], ['e3', 'other']] | [['e2', 'song'], ['e3', 'other']] | Passed |
| fixture 2 | [] | [] | Passed |
| fixture 3 | [['a', 'song']] | [['a', 'song']] | Passed |
| fixture 4 | [] | [] | Passed |
SHA-256 / 066fa82747565db9a29d90b0efc8ddf79d3ca2704d10e9c1896310d791d1e3f8
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 2026-09-29T14:38:44.468133+00:00.
Case digest / 1756e35fe3a6eabca7bc5376f806cb3e61b86fa1be486bf58f0b727cc1296f63