FA-11111 / Streaming segment lifecycle / Open access

Live window prune absolute sequence · case 01

An absolute sequence number is applied as a local array slice offset.

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

ROOT CAUSE

An absolute sequence number is applied as a local array slice offset.

VERIFIED REPAIR

Preserve the media contract: Drop segments older than an absolute first available media sequence, retaining the boundary sequence.

Unsuccessful approach: Strict comparison discards the earliest still-available segment.

Case contract

Drop segments older than an absolute first available media sequence, retaining the boundary sequence.

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, first_sequence):
    return segments[first_sequence:]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('fixture 1',solve(*([[100, 'a'], [101, 'b'], [102, 'c']], 101)),[[101, 'b'], [102, 'c']])
check('fixture 2',solve(*([[5, 'x']], 5)),[[5, 'x']])
check('fixture 3',solve(*([[5, 'x']], 6)),[])
check('fixture 4',solve(*([], 0)),[])
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	`[]`	`[[101, 'b'], [102, 'c']]`	Failed
fixture 2	`[]`	`[[5, 'x']]`	Failed
fixture 3	`[]`	`[]`	Passed
fixture 4	`[]`	`[]`	Passed

SHA-256 / ffb55672c10a6a33cedf93de4e167531f5fe25dc939e1aba3ed8caf89be5af6a

2 / The unsuccessful fix

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json
import math
N = 1
observations = []
def solve(segments, first_sequence):
    return [x for x in segments if x[0]>first_sequence]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('fixture 1',solve(*([[100, 'a'], [101, 'b'], [102, 'c']], 101)),[[101, 'b'], [102, 'c']])
check('fixture 2',solve(*([[5, 'x']], 5)),[[5, 'x']])
check('fixture 3',solve(*([[5, 'x']], 6)),[])
check('fixture 4',solve(*([], 0)),[])
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	`[[102, 'c']]`	`[[101, 'b'], [102, 'c']]`	Failed
fixture 2	`[]`	`[[5, 'x']]`	Failed
fixture 3	`[]`	`[]`	Passed
fixture 4	`[]`	`[]`	Passed

SHA-256 / 837567e729cdb5c9b8d33e847853c5bb145d260b693fa47cccaadb585abc92eb

3 / The verified repair

Exit 0

"""Failure Map reference implementation. Python standard library only."""
import json
import math
N = 1
observations = []
def solve(segments, first_sequence):
    return [x for x in segments if x[0]>=first_sequence]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('fixture 1',solve(*([[100, 'a'], [101, 'b'], [102, 'c']], 101)),[[101, 'b'], [102, 'c']])
check('fixture 2',solve(*([[5, 'x']], 5)),[[5, 'x']])
check('fixture 3',solve(*([[5, 'x']], 6)),[])
check('fixture 4',solve(*([], 0)),[])
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	`[[101, 'b'], [102, 'c']]`	`[[101, 'b'], [102, 'c']]`	Passed
fixture 2	`[[5, 'x']]`	`[[5, 'x']]`	Passed
fixture 3	`[]`	`[]`	Passed
fixture 4	`[]`	`[]`	Passed

SHA-256 / c1413b5a76bfc47b6b4f36012596fb3c19bb5b9e5a0ca815d4a1d05b201c5f59

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 2026-09-29T14:38:44.995587+00:00.

Case digest / 611c2d38c70897490a5b8a7e4822afe96f6799282e3889bf1193b16e0a7ae03d