FA-11151 / Streaming segment lifecycle / Open access
Partial segment replacement · case 01
A retried part is appended as a duplicate part rather than updating its stored payload.
ROOT CAUSE
A retried part is appended as a duplicate part rather than updating its stored payload.
VERIFIED REPAIR
Preserve the media contract: Parts are sorted unique [part index,payload]. Replace one completed part or insert a new part, preserving sorted unique indexes.
Unsuccessful approach: Removing the previous partial segment without inserting its replacement loses the data.
Case contract
Parts are sorted unique [part index,payload]. Replace one completed part or insert a new part, preserving sorted unique indexes.
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(parts, index, payload):
return list(parts)+[[index,payload]]
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('fixture 1',solve(*([[0, 'a'], [1, 'old']], 1, 'new')),[[0, 'a'], [1, 'new']])
check('fixture 2',solve(*([[1, 'b']], 0, 'a')),[[0, 'a'], [1, 'b']])
check('fixture 3',solve(*([], 0, 'a')),[[0, 'a']])
check('fixture 4',solve(*([[0, 'a']], 0, 'a')),[[0, '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 | [[0, 'a'], [1, 'old'], [1, 'new']] | [[0, 'a'], [1, 'new']] | Failed |
| fixture 2 | [[1, 'b'], [0, 'a']] | [[0, 'a'], [1, 'b']] | Failed |
| fixture 3 | [[0, 'a']] | [[0, 'a']] | Passed |
| fixture 4 | [[0, 'a'], [0, 'a']] | [[0, 'a']] | Failed |
SHA-256 / 7aca01ffb4cc5ae346b35d127d164c55202b3e59723668771125a48bd8043a31
2 / The unsuccessful fix
Exit 1"""Failure Map reference implementation. Python standard library only."""
import json
import math
N = 1
observations = []
def solve(parts, index, payload):
return [[i,data] for i,data in parts if i!=index]
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('fixture 1',solve(*([[0, 'a'], [1, 'old']], 1, 'new')),[[0, 'a'], [1, 'new']])
check('fixture 2',solve(*([[1, 'b']], 0, 'a')),[[0, 'a'], [1, 'b']])
check('fixture 3',solve(*([], 0, 'a')),[[0, 'a']])
check('fixture 4',solve(*([[0, 'a']], 0, 'a')),[[0, '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 | [[0, 'a']] | [[0, 'a'], [1, 'new']] | Failed |
| fixture 2 | [[1, 'b']] | [[0, 'a'], [1, 'b']] | Failed |
| fixture 3 | [] | [[0, 'a']] | Failed |
| fixture 4 | [] | [[0, 'a']] | Failed |
SHA-256 / 5a84e42b7dd2bdbe75e1796f5de0a1e3b0e15395d03cb6acd7acddbd069a9b2e
3 / The verified repair
Exit 0"""Failure Map reference implementation. Python standard library only."""
import json
import math
N = 1
observations = []
def solve(parts, index, payload):
return [[i,(payload if i==index else data)] for i,data in parts] if any(i==index for i,data in parts) else sorted(list(parts)+[[index,payload]])
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('fixture 1',solve(*([[0, 'a'], [1, 'old']], 1, 'new')),[[0, 'a'], [1, 'new']])
check('fixture 2',solve(*([[1, 'b']], 0, 'a')),[[0, 'a'], [1, 'b']])
check('fixture 3',solve(*([], 0, 'a')),[[0, 'a']])
check('fixture 4',solve(*([[0, 'a']], 0, 'a')),[[0, '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 | [[0, 'a'], [1, 'new']] | [[0, 'a'], [1, 'new']] | Passed |
| fixture 2 | [[0, 'a'], [1, 'b']] | [[0, 'a'], [1, 'b']] | Passed |
| fixture 3 | [[0, 'a']] | [[0, 'a']] | Passed |
| fixture 4 | [[0, 'a']] | [[0, 'a']] | Passed |
SHA-256 / 6e0c3188824d1a9f20a760b219f36bc02951d8c6377e4d5beb4d2b8c753e31c8
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 2026-09-29T14:38:45.441306+00:00.
Case digest / f74a55745c3eb155d4b3dfd3684d0a680ba9e3cd7b7fb865c27446a21f096e96