FA-11191 / Streaming segment lifecycle / Open access

Rendition switch discards old pending · case 01

Quality switching leaves obsolete old-rendition downloads queued.

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

ROOT CAUSE

Quality switching leaves obsolete old-rendition downloads queued.

THE FAILURE

Quality switching leaves obsolete old-rendition downloads queued.

Unsuccessful approach: Replacing the entire queue cancels unrelated media tracks.

Case contract

Pending entries are [rendition,sequence]. A switch replaces only pending work from the old rendition; unrelated audio/track work remains.

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(pending, old_rendition, replacement):
    return list(pending)+list(replacement)
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('fixture 1',solve(*([['low', 1], ['audio', 1]], 'low', [['high', 1]])),[['audio', 1], ['high', 1]])
check('fixture 2',solve(*([['low', 1]], 'low', [])),[])
check('fixture 3',solve(*([], 'low', [['high', 2]])),[['high', 2]])
check('fixture 4',solve(*([['audio', 2]], 'low', [])),[['audio', 2]])
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	`[['low', 1], ['audio', 1], ['high', 1]]`	`[['audio', 1], ['high', 1]]`	Failed
fixture 2	`[['low', 1]]`	`[]`	Failed
fixture 3	`[['high', 2]]`	`[['high', 2]]`	Passed
fixture 4	`[['audio', 2]]`	`[['audio', 2]]`	Passed

SHA-256 / b3aacd901cea02660e23ee7561860397d94a121db63ad1280e138f5300c9fbf0

2 / The unsuccessful fix

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json
import math
N = 1
observations = []
def solve(pending, old_rendition, replacement):
    return list(replacement)
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('fixture 1',solve(*([['low', 1], ['audio', 1]], 'low', [['high', 1]])),[['audio', 1], ['high', 1]])
check('fixture 2',solve(*([['low', 1]], 'low', [])),[])
check('fixture 3',solve(*([], 'low', [['high', 2]])),[['high', 2]])
check('fixture 4',solve(*([['audio', 2]], 'low', [])),[['audio', 2]])
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	`[['high', 1]]`	`[['audio', 1], ['high', 1]]`	Failed
fixture 2	`[]`	`[]`	Passed
fixture 3	`[['high', 2]]`	`[['high', 2]]`	Passed
fixture 4	`[]`	`[['audio', 2]]`	Failed

SHA-256 / 4a6ed85f757056cece18aff8ef6c37565caace664681ed379acc120959cda78b

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 2026-09-29T14:38:45.683577+00:00.

Case digest / ccb3e42f0898ce6078d10aa698d1227386bfe6615daf0d404803ecb6da80abfa