FA-11116 / Streaming segment lifecycle / Open access
Discontinuity base increments on prune · case 01
A sliding manifest window loses discontinuity history when old segments disappear.
ROOT CAUSE
A sliding manifest window loses discontinuity history when old segments disappear.
THE FAILURE
A sliding manifest window loses discontinuity history when old segments disappear.
Unsuccessful approach: Including the first retained segment marker counts it both in the base and retained list.
Case contract
Each segment marks whether a discontinuity precedes it. When pruning sequences below keep_from, advance the retained-window discontinuity base by only pruned markers.
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(base, segments, keep_from):
return base
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('fixture 1',solve(*(3, [[10, False], [11, True], [12, True]], 12)),4)
check('fixture 2',solve(*(0, [[1, True]], 1)),0)
check('fixture 3',solve(*(2, [], 10)),2)
check('fixture 4',solve(*(1, [[2, True], [3, True]], 4)),3)
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 | 3 | 4 | Failed |
| fixture 2 | 0 | 0 | Passed |
| fixture 3 | 2 | 2 | Passed |
| fixture 4 | 1 | 3 | Failed |
SHA-256 / 233430fc60f94f3118dd3a3ce7590ef175797c87f5236380becd1b759427eb72
2 / The unsuccessful fix
Exit 1"""Failure Map reference implementation. Python standard library only."""
import json
import math
N = 1
observations = []
def solve(base, segments, keep_from):
return base+sum(bool(discontinuity) for sequence,discontinuity in segments if sequence<=keep_from)
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('fixture 1',solve(*(3, [[10, False], [11, True], [12, True]], 12)),4)
check('fixture 2',solve(*(0, [[1, True]], 1)),0)
check('fixture 3',solve(*(2, [], 10)),2)
check('fixture 4',solve(*(1, [[2, True], [3, True]], 4)),3)
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 | 5 | 4 | Failed |
| fixture 2 | 1 | 0 | Failed |
| fixture 3 | 2 | 2 | Passed |
| fixture 4 | 3 | 3 | Passed |
SHA-256 / c21b2f2a73ddd2ec5f276a80465138355349da629313113617979c484c59058f
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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Sign in to the archive ↗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 2026-09-29T14:38:45.037532+00:00.
Case digest / 331abf521fa7f33247054bcec84020e5e86e95066175fc2ec0bd79e8eee8b409