FA-12281 / Power metering accounting / Open access

Expired export-credit lots reduce current import charges · case 01

Expired export-credit lots reduce current import charges.

Verified by executionVariant 1 · 6 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

Expired lots remain spendable against the current bill.

VERIFIED REPAIR

Filter by inclusive expiry and consume in ascending expiry order.

Unsuccessful approach: Filtering expired lots but consuming newest first strands older credits that expire sooner.

Case contract

Lots [expiry_period, energy] are export credits. At billing period p, keep only expiry>=p, consume oldest-expiring lots first against nonnegative import need, and return [uncovered need, remaining energy by ascending expiry]. Expired lots vanish; zero remainders are omitted.

Why this case matters

Meter settlement depends on explicit register and tariff policies; this controlled model makes that policy observable.

1 / The failure

Exit 1

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

N = 1
observations = []
def solve(lots, period, need):
    out=[]
    for expiry,energy in sorted(lots):
        used=min(need,energy); need-=used
        if energy>used: out.append([expiry,energy-used])
    return [need,out]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('expired credit', solve([[1,N]],2,N),[N,[]])
check('oldest spent first', solve([[3,N],[2,N]],2,N),[0,[[3,N]]])
check('inclusive expiry', solve([[2,N]],2,N),[0,[]])
check('partial credit', solve([[2,3*N]],2,N),[0,[[2,2*N]]])
check('uncovered import', solve([[2,N]],2,3*N),[2*N,[]])
check('zero import still expires lots', solve([[1,N],[3,N]],2,0),[0,[[3,N]]])
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
expired credit	`[0, []]`	`[1, []]`	Failed
oldest spent first	`[0, [[3, 1]]]`	`[0, [[3, 1]]]`	Passed
inclusive expiry	`[0, []]`	`[0, []]`	Passed
partial credit	`[0, [[2, 2]]]`	`[0, [[2, 2]]]`	Passed
uncovered import	`[2, []]`	`[2, []]`	Passed
zero import still expires lots	`[0, [[1, 1], [3, 1]]]`	`[0, [[3, 1]]]`	Failed

SHA-256 / 5dab0d05c2f8ad86a16c1d37b144273cab1f4c7b98d3be5f13bd37b42fd326f5

2 / The unsuccessful fix

Exit 1

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

N = 1
observations = []
def solve(lots, period, need):
    out=[]
    for expiry,energy in sorted(lots,reverse=True):
        if expiry<period: continue
        used=min(need,energy); need-=used
        if energy>used: out.append([expiry,energy-used])
    return [need,sorted(out)]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('expired credit', solve([[1,N]],2,N),[N,[]])
check('oldest spent first', solve([[3,N],[2,N]],2,N),[0,[[3,N]]])
check('inclusive expiry', solve([[2,N]],2,N),[0,[]])
check('partial credit', solve([[2,3*N]],2,N),[0,[[2,2*N]]])
check('uncovered import', solve([[2,N]],2,3*N),[2*N,[]])
check('zero import still expires lots', solve([[1,N],[3,N]],2,0),[0,[[3,N]]])
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
expired credit	`[1, []]`	`[1, []]`	Passed
oldest spent first	`[0, [[2, 1]]]`	`[0, [[3, 1]]]`	Failed
inclusive expiry	`[0, []]`	`[0, []]`	Passed
partial credit	`[0, [[2, 2]]]`	`[0, [[2, 2]]]`	Passed
uncovered import	`[2, []]`	`[2, []]`	Passed
zero import still expires lots	`[0, [[3, 1]]]`	`[0, [[3, 1]]]`	Passed

SHA-256 / f91867feb9fdd52992e3541d5cdf38319256c54a1a26a3a35488cfa940a55af3

3 / The verified repair

Exit 0

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

N = 1
observations = []
def solve(lots, period, need):
    out=[]
    for expiry,energy in sorted(lots):
        if expiry<period: continue
        used=min(need,energy); need-=used
        if energy>used: out.append([expiry,energy-used])
    return [need,out]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('expired credit', solve([[1,N]],2,N),[N,[]])
check('oldest spent first', solve([[3,N],[2,N]],2,N),[0,[[3,N]]])
check('inclusive expiry', solve([[2,N]],2,N),[0,[]])
check('partial credit', solve([[2,3*N]],2,N),[0,[[2,2*N]]])
check('uncovered import', solve([[2,N]],2,3*N),[2*N,[]])
check('zero import still expires lots', solve([[1,N],[3,N]],2,0),[0,[[3,N]]])
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
expired credit	`[1, []]`	`[1, []]`	Passed
oldest spent first	`[0, [[3, 1]]]`	`[0, [[3, 1]]]`	Passed
inclusive expiry	`[0, []]`	`[0, []]`	Passed
partial credit	`[0, [[2, 2]]]`	`[0, [[2, 2]]]`	Passed
uncovered import	`[2, []]`	`[2, []]`	Passed
zero import still expires lots	`[0, [[3, 1]]]`	`[0, [[3, 1]]]`	Passed

SHA-256 / 5253aa83e2c277462e8a3182ab641810e39237e3703362e6cadfb1eade2fbcc5

Verification & scope

Simplified integer-energy accounting model; no hardware protocol, legal tariff, measurement uncertainty, or live grid behavior is represented. 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 2026-09-29T14:38:55.552157+00:00.

Case digest / 1704d0f800cb0c128bb346fa33dca9200738ae63b7a90e3314d297e97e5aab66