FA-11161 / Streaming segment lifecycle / Open access
Segment eviction retains shared init · case 01
Evicting one media segment deletes initialization bytes needed by other segments.
ROOT CAUSE
Evicting one media segment deletes initialization bytes needed by other segments.
VERIFIED REPAIR
Preserve the media contract: Segments are [ID,initialization-object ID]. Evict the named segment and collect init objects with no remaining references; preserve shared init data.
Unsuccessful approach: Never collecting init objects leaks unreferenced decoder initialization data.
Case contract
Segments are [ID,initialization-object ID]. Evict the named segment and collect init objects with no remaining references; preserve shared init data.
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(segments, remove, init_objects):
return [[x for x in segments if x[0]!=remove],[]]
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('fixture 1',solve(*([[1, 'i'], [2, 'i']], 1, ['i'])),[[[2, 'i']], ['i']])
check('fixture 2',solve(*([[1, 'i']], 1, ['i'])),[[], []])
check('fixture 3',solve(*([[1, 'i'], [2, 'j']], 1, ['i', 'j'])),[[[2, 'j']], ['j']])
check('fixture 4',solve(*([], 4, [])),[[], []])
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 | [[[2, 'i']], []] | [[[2, 'i']], ['i']] | Failed |
| fixture 2 | [[], []] | [[], []] | Passed |
| fixture 3 | [[[2, 'j']], []] | [[[2, 'j']], ['j']] | Failed |
| fixture 4 | [[], []] | [[], []] | Passed |
SHA-256 / aadf6efa7c8f19181ba8930507451ac6aa7eb55dd1d9d7cd314b05af8d1c83a1
2 / The unsuccessful fix
Exit 1"""Failure Map reference implementation. Python standard library only."""
import json
import math
N = 1
observations = []
def solve(segments, remove, init_objects):
return [[x for x in segments if x[0]!=remove],list(init_objects)]
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('fixture 1',solve(*([[1, 'i'], [2, 'i']], 1, ['i'])),[[[2, 'i']], ['i']])
check('fixture 2',solve(*([[1, 'i']], 1, ['i'])),[[], []])
check('fixture 3',solve(*([[1, 'i'], [2, 'j']], 1, ['i', 'j'])),[[[2, 'j']], ['j']])
check('fixture 4',solve(*([], 4, [])),[[], []])
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 | [[[2, 'i']], ['i']] | [[[2, 'i']], ['i']] | Passed |
| fixture 2 | [[], ['i']] | [[], []] | Failed |
| fixture 3 | [[[2, 'j']], ['i', 'j']] | [[[2, 'j']], ['j']] | Failed |
| fixture 4 | [[], []] | [[], []] | Passed |
SHA-256 / f3f4c8b796ea2af5c6a8585bade6d553bb9c434817fd9fc35f05edbadb461d3d
3 / The verified repair
Exit 0"""Failure Map reference implementation. Python standard library only."""
import json
import math
N = 1
observations = []
def solve(segments, remove, init_objects):
return [[x for x in segments if x[0]!=remove],[i for i in init_objects if any(x[0]!=remove and x[1]==i for x in segments)]]
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('fixture 1',solve(*([[1, 'i'], [2, 'i']], 1, ['i'])),[[[2, 'i']], ['i']])
check('fixture 2',solve(*([[1, 'i']], 1, ['i'])),[[], []])
check('fixture 3',solve(*([[1, 'i'], [2, 'j']], 1, ['i', 'j'])),[[[2, 'j']], ['j']])
check('fixture 4',solve(*([], 4, [])),[[], []])
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 | [[[2, 'i']], ['i']] | [[[2, 'i']], ['i']] | Passed |
| fixture 2 | [[], []] | [[], []] | Passed |
| fixture 3 | [[[2, 'j']], ['j']] | [[[2, 'j']], ['j']] | Passed |
| fixture 4 | [[], []] | [[], []] | Passed |
SHA-256 / e13fe481323981cd54fefa638a387c6091c5b3e9e9e0be0a2b4fc23b997cf2e7
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 2026-09-29T14:38:45.525287+00:00.
Case digest / bfb2a2a8cfa0fe1eba67cf913e62199ab07e66a7778a55e2a0021cf0e967e5d5