FA-10486 / Caching / Open access

Updating one cached representation removes sibling variants · case 01

Updating one cached representation removes sibling variants.

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

ROOT CAUSE

Representation replacement filters by resource without retaining its variant dimension.

THE FAILURE

Representation replacement filters by resource without retaining its variant dimension.

Unsuccessful approach: Filtering by variant alone deletes matching variants of different resources.

Case contract

Unique entries are [resource,variant,value]. Replace only the exact pair and append its updated representation, preserving every other entry in order.

Why this case matters

A deterministic cache state transformation. Inputs are copied or treated as immutable; no remote storage, real clock, or concurrent interleaving is simulated.

1 / The failure

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(entries, resource, variant, value):
    return [x for x in entries if x[0]!=resource]+[[resource,variant,value]]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('fixture 1', solve(*([['r', 'en', 1], ['r', 'fr', 2]], 'r', 'en', 3)), [['r', 'fr', 2], ['r', 'en', 3]])
check('fixture 2', solve(*([['r', 'en', 1], ['s', 'en', 2]], 'r', 'en', 3)), [['s', 'en', 2], ['r', 'en', 3]])
check('fixture 3', solve(*([], 'r', 'en', 0)), [['r', 'en', 0]])
check('fixture 4', solve(*([['r', 'fr', 2]], 'r', 'en', 3)), [['r', 'fr', 2], ['r', 'en', 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	`[['r', 'en', 3]]`	`[['r', 'fr', 2], ['r', 'en', 3]]`	Failed
fixture 2	`[['s', 'en', 2], ['r', 'en', 3]]`	`[['s', 'en', 2], ['r', 'en', 3]]`	Passed
fixture 3	`[['r', 'en', 0]]`	`[['r', 'en', 0]]`	Passed
fixture 4	`[['r', 'en', 3]]`	`[['r', 'fr', 2], ['r', 'en', 3]]`	Failed

SHA-256 / d7c6e91aebb4834ea25b2c300f18ce51245d26d118d6f5c76b37264a6107743f

2 / The unsuccessful fix

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(entries, resource, variant, value):
    return [x for x in entries if x[1]!=variant]+[[resource,variant,value]]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('fixture 1', solve(*([['r', 'en', 1], ['r', 'fr', 2]], 'r', 'en', 3)), [['r', 'fr', 2], ['r', 'en', 3]])
check('fixture 2', solve(*([['r', 'en', 1], ['s', 'en', 2]], 'r', 'en', 3)), [['s', 'en', 2], ['r', 'en', 3]])
check('fixture 3', solve(*([], 'r', 'en', 0)), [['r', 'en', 0]])
check('fixture 4', solve(*([['r', 'fr', 2]], 'r', 'en', 3)), [['r', 'fr', 2], ['r', 'en', 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	`[['r', 'fr', 2], ['r', 'en', 3]]`	`[['r', 'fr', 2], ['r', 'en', 3]]`	Passed
fixture 2	`[['r', 'en', 3]]`	`[['s', 'en', 2], ['r', 'en', 3]]`	Failed
fixture 3	`[['r', 'en', 0]]`	`[['r', 'en', 0]]`	Passed
fixture 4	`[['r', 'fr', 2], ['r', 'en', 3]]`	`[['r', 'fr', 2], ['r', 'en', 3]]`	Passed

SHA-256 / 77dfa4bfa5fd60889cf21ea76fc8058f48a90223a39c1936861c4c8188930e87

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 2026-09-29T14:38:39.395540+00:00.

Case digest / 39a91bbe8e80b7af810e0c468e4ab7b201d3c7c1fa9eaa7e4041c22b3b6f0a23