FA-11236 / Media timeline seeking / Open access

Live edge minus holdback · case 01

Live playback starts at the unstable edge instead of behind the holdback.

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

ROOT CAUSE

Live playback starts at the unstable edge instead of behind the holdback.

THE FAILURE

Live playback starts at the unstable edge instead of behind the holdback.

Unsuccessful approach: Unclamped holdback can select a time before retained media.

Case contract

For this contiguous live-window policy, return latest end minus nonnegative holdback clamped to earliest start; empty ranges return None. No gap correction is included.

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(ranges, holdback):
    return ranges[-1][1] if ranges else None
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('fixture 1',solve(*([[10, 20]], 3)),17)
check('fixture 2',solve(*([[10, 20]], 30)),10)
check('fixture 3',solve(*([], 3)),None)
check('fixture 4',solve(*([[0, 10]], 0)),10)
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	`20`	`17`	Failed
fixture 2	`20`	`10`	Failed
fixture 3	`None`	`None`	Passed
fixture 4	`10`	`10`	Passed

SHA-256 / 1665b45824e62a89bcfdeeb67798f2922ffa25e32dce861b2b2305e7ccc37fd2

2 / The unsuccessful fix

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json
import math
N = 1
observations = []
def solve(ranges, holdback):
    return ranges[-1][1]-holdback if ranges else None
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('fixture 1',solve(*([[10, 20]], 3)),17)
check('fixture 2',solve(*([[10, 20]], 30)),10)
check('fixture 3',solve(*([], 3)),None)
check('fixture 4',solve(*([[0, 10]], 0)),10)
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	`17`	`17`	Passed
fixture 2	`-10`	`10`	Failed
fixture 3	`None`	`None`	Passed
fixture 4	`10`	`10`	Passed

SHA-256 / a9a90a966daec0e54483490779f015964c201efab98235d154032bfdb12121d5

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.

Member access is invitation-based. Sign in with your invited account to inspect the repair.

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 2026-09-29T14:38:46.174693+00:00.

Case digest / 1e8ec67bcde7aeb8194cdec52b79c4a72056514ce3bc6f7892b20fe57834ca99