FA-93296 / EV charging session scheduling / Open access
Staggered start after tariff switch: stagger base time · case 01
Chargers plugged in after the tariff switch are scheduled to start in the past.
ROOT CAUSE
The stagger is added to the tariff start without considering the current time.
VERIFIED REPAIR
Stagger from max(tariff_start, now).
Unsuccessful approach: Staggering from now ignores the tariff switch and starts on the expensive tariff.
Case contract
To avoid a demand spike at a tariff switch each charger delays its start by delay = sum((i+1)*ord(c) for i, c in enumerate(cid)) % (max_delay+1) minutes after max(tariff_start, now). If that start is later than depart - dur it is pulled back to max(depart - dur, now). Status is 'ok' when start + dur <= depart else 'late'. Return [start, delay, status].
Why this case matters
Depot, workplace and public EV chargers schedule sessions against prices, circuit limits and departure deadlines; a wrong decision silently strands a driver or overloads a feeder.
1 / The failure
Exit 1"""Failure Map reference implementation. Python standard library only."""
import json
N = 1
observations = []
def solve(cid, tariff_start, now, depart, dur, max_delay):
delay = sum((i + 1) * ord(c) for i, c in enumerate(cid)) % (max_delay + 1)
start = tariff_start + delay
latest = depart - dur
if start > latest:
start = max(latest, now)
status = 'ok' if start + dur <= depart else 'late'
return [start, delay, status]
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[['boundary: no stagger configured', ['CP7', 100, 50, 400, 60, 0], [100, 0, 'ok']],
['boundary: deadline forces immediate start', ['CP12', 100, 50, 120, 70, 30], [50, 16, 'ok']],
['boundary: tariff already active', ['CP3', 10, 50, 400, 60, 10], [56, 6, 'ok']],
['regression: stagger base time', ['CP201', 49, 94, 552, 247, 5], [98, 4, 'ok']],
['regression: stagger base time (partial repair)', ['CP778', 179, 65, 525, 61, 0],
[179, 0, 'ok']],
['control 1', ['CP310', 208, 18, 199, 159, 0], [40, 0, 'ok']],
['control 2', ['CP766', 294, 150, 208, 201, 30], [150, 10, 'late']]],
[['boundary: no stagger configured', ['CP7', 100, 50, 400, 60, 0], [100, 0, 'ok']],
['boundary: deadline forces immediate start', ['CP12', 100, 50, 120, 70, 30], [50, 16, 'ok']],
['boundary: tariff already active', ['CP3', 10, 50, 400, 60, 10], [56, 6, 'ok']],
['regression: stagger base time', ['CP321', 7, 32, 498, 89, 15], [41, 9, 'ok']],
['regression: stagger base time (partial repair)', ['CP363', 205, 166, 509, 88, 10],
[209, 4, 'ok']],
['control 1', ['CP883', 235, 120, 211, 80, 5], [131, 4, 'ok']],
['control 2', ['CP742', 19, 177, 199, 247, 10], [177, 3, 'late']]],
[['boundary: no stagger configured', ['CP7', 100, 50, 400, 60, 0], [100, 0, 'ok']],
['boundary: deadline forces immediate start', ['CP12', 100, 50, 120, 70, 30], [50, 16, 'ok']],
['boundary: tariff already active', ['CP3', 10, 50, 400, 60, 10], [56, 6, 'ok']],
['regression: stagger base time', ['CP473', 52, 113, 448, 84, 0], [113, 0, 'ok']],
['regression: stagger base time (partial repair)', ['CP201', 269, 83, 492, 35, 10],
[269, 0, 'ok']],
['control 1', ['CP783', 204, 99, 341, 202, 5], [139, 1, 'ok']],
['control 2', ['CP490', 211, 107, 512, 167, 10], [215, 4, 'ok']]],
[['boundary: no stagger configured', ['CP7', 100, 50, 400, 60, 0], [100, 0, 'ok']],
['boundary: deadline forces immediate start', ['CP12', 100, 50, 120, 70, 30], [50, 16, 'ok']],
['boundary: tariff already active', ['CP3', 10, 50, 400, 60, 10], [56, 6, 'ok']],
['regression: stagger base time', ['CP951', 78, 134, 388, 193, 0], [134, 0, 'ok']],
['regression: stagger base time (partial repair)', ['CP907', 199, 117, 410, 31, 0],
[199, 0, 'ok']],
['control 1', ['CP137', 10, 19, 66, 6, 15], [24, 5, 'ok']],
['control 2', ['CP783', 210, 193, 350, 267, 30], [193, 3, 'late']]],
[['boundary: no stagger configured', ['CP7', 100, 50, 400, 60, 0], [100, 0, 'ok']],
['boundary: deadline forces immediate start', ['CP12', 100, 50, 120, 70, 30], [50, 16, 'ok']],
['boundary: tariff already active', ['CP3', 10, 50, 400, 60, 10], [56, 6, 'ok']],
['regression: stagger base time', ['CP544', 22, 72, 471, 102, 5], [74, 2, 'ok']],
['regression: stagger base time (partial repair)', ['CP353', 241, 118, 320, 150, 5],
[170, 1, 'ok']],
['control 1', ['CP873', 194, 7, 146, 117, 15], [29, 6, 'ok']],
['control 2', ['CP733', 56, 136, 418, 4, 0], [136, 0, 'ok']]]]
for label, args, expected in fixtures[N-1]:
check(label, solve(*args), expected)
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 |
|---|---|---|---|
| boundary: no stagger configured | [100, 0, 'ok'] | [100, 0, 'ok'] | Passed |
| boundary: deadline forces immediate start | [50, 16, 'ok'] | [50, 16, 'ok'] | Passed |
| boundary: tariff already active | [16, 6, 'ok'] | [56, 6, 'ok'] | Failed |
| regression: stagger base time | [53, 4, 'ok'] | [98, 4, 'ok'] | Failed |
| regression: stagger base time (partial repair) | [179, 0, 'ok'] | [179, 0, 'ok'] | Passed |
| control 1 | [40, 0, 'ok'] | [40, 0, 'ok'] | Passed |
| control 2 | [150, 10, 'late'] | [150, 10, 'late'] | Passed |
SHA-256 / 22ba04f6720bfb5ffa258ab6d687aa06a2c341941b98b076dbfa1fb1edadbd1f
2 / The unsuccessful fix
Exit 1"""Failure Map reference implementation. Python standard library only."""
import json
N = 1
observations = []
def solve(cid, tariff_start, now, depart, dur, max_delay):
delay = sum((i + 1) * ord(c) for i, c in enumerate(cid)) % (max_delay + 1)
start = now + delay
latest = depart - dur
if start > latest:
start = max(latest, now)
status = 'ok' if start + dur <= depart else 'late'
return [start, delay, status]
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[['boundary: no stagger configured', ['CP7', 100, 50, 400, 60, 0], [100, 0, 'ok']],
['boundary: deadline forces immediate start', ['CP12', 100, 50, 120, 70, 30], [50, 16, 'ok']],
['boundary: tariff already active', ['CP3', 10, 50, 400, 60, 10], [56, 6, 'ok']],
['regression: stagger base time', ['CP201', 49, 94, 552, 247, 5], [98, 4, 'ok']],
['regression: stagger base time (partial repair)', ['CP778', 179, 65, 525, 61, 0],
[179, 0, 'ok']],
['control 1', ['CP310', 208, 18, 199, 159, 0], [40, 0, 'ok']],
['control 2', ['CP766', 294, 150, 208, 201, 30], [150, 10, 'late']]],
[['boundary: no stagger configured', ['CP7', 100, 50, 400, 60, 0], [100, 0, 'ok']],
['boundary: deadline forces immediate start', ['CP12', 100, 50, 120, 70, 30], [50, 16, 'ok']],
['boundary: tariff already active', ['CP3', 10, 50, 400, 60, 10], [56, 6, 'ok']],
['regression: stagger base time', ['CP321', 7, 32, 498, 89, 15], [41, 9, 'ok']],
['regression: stagger base time (partial repair)', ['CP363', 205, 166, 509, 88, 10],
[209, 4, 'ok']],
['control 1', ['CP883', 235, 120, 211, 80, 5], [131, 4, 'ok']],
['control 2', ['CP742', 19, 177, 199, 247, 10], [177, 3, 'late']]],
[['boundary: no stagger configured', ['CP7', 100, 50, 400, 60, 0], [100, 0, 'ok']],
['boundary: deadline forces immediate start', ['CP12', 100, 50, 120, 70, 30], [50, 16, 'ok']],
['boundary: tariff already active', ['CP3', 10, 50, 400, 60, 10], [56, 6, 'ok']],
['regression: stagger base time', ['CP473', 52, 113, 448, 84, 0], [113, 0, 'ok']],
['regression: stagger base time (partial repair)', ['CP201', 269, 83, 492, 35, 10],
[269, 0, 'ok']],
['control 1', ['CP783', 204, 99, 341, 202, 5], [139, 1, 'ok']],
['control 2', ['CP490', 211, 107, 512, 167, 10], [215, 4, 'ok']]],
[['boundary: no stagger configured', ['CP7', 100, 50, 400, 60, 0], [100, 0, 'ok']],
['boundary: deadline forces immediate start', ['CP12', 100, 50, 120, 70, 30], [50, 16, 'ok']],
['boundary: tariff already active', ['CP3', 10, 50, 400, 60, 10], [56, 6, 'ok']],
['regression: stagger base time', ['CP951', 78, 134, 388, 193, 0], [134, 0, 'ok']],
['regression: stagger base time (partial repair)', ['CP907', 199, 117, 410, 31, 0],
[199, 0, 'ok']],
['control 1', ['CP137', 10, 19, 66, 6, 15], [24, 5, 'ok']],
['control 2', ['CP783', 210, 193, 350, 267, 30], [193, 3, 'late']]],
[['boundary: no stagger configured', ['CP7', 100, 50, 400, 60, 0], [100, 0, 'ok']],
['boundary: deadline forces immediate start', ['CP12', 100, 50, 120, 70, 30], [50, 16, 'ok']],
['boundary: tariff already active', ['CP3', 10, 50, 400, 60, 10], [56, 6, 'ok']],
['regression: stagger base time', ['CP544', 22, 72, 471, 102, 5], [74, 2, 'ok']],
['regression: stagger base time (partial repair)', ['CP353', 241, 118, 320, 150, 5],
[170, 1, 'ok']],
['control 1', ['CP873', 194, 7, 146, 117, 15], [29, 6, 'ok']],
['control 2', ['CP733', 56, 136, 418, 4, 0], [136, 0, 'ok']]]]
for label, args, expected in fixtures[N-1]:
check(label, solve(*args), expected)
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 |
|---|---|---|---|
| boundary: no stagger configured | [50, 0, 'ok'] | [100, 0, 'ok'] | Failed |
| boundary: deadline forces immediate start | [50, 16, 'ok'] | [50, 16, 'ok'] | Passed |
| boundary: tariff already active | [56, 6, 'ok'] | [56, 6, 'ok'] | Passed |
| regression: stagger base time | [98, 4, 'ok'] | [98, 4, 'ok'] | Passed |
| regression: stagger base time (partial repair) | [65, 0, 'ok'] | [179, 0, 'ok'] | Failed |
| control 1 | [18, 0, 'ok'] | [40, 0, 'ok'] | Failed |
| control 2 | [150, 10, 'late'] | [150, 10, 'late'] | Passed |
SHA-256 / 4f82245a630d6f52f4ffd950c1afbd3cf9bf7c420bfe7fdf15e8d90cc60e565c
3 / The verified repair
Exit 0"""Failure Map reference implementation. Python standard library only."""
import json
N = 1
observations = []
def solve(cid, tariff_start, now, depart, dur, max_delay):
delay = sum((i + 1) * ord(c) for i, c in enumerate(cid)) % (max_delay + 1)
start = max(tariff_start, now) + delay
latest = depart - dur
if start > latest:
start = max(latest, now)
status = 'ok' if start + dur <= depart else 'late'
return [start, delay, status]
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[['boundary: no stagger configured', ['CP7', 100, 50, 400, 60, 0], [100, 0, 'ok']],
['boundary: deadline forces immediate start', ['CP12', 100, 50, 120, 70, 30], [50, 16, 'ok']],
['boundary: tariff already active', ['CP3', 10, 50, 400, 60, 10], [56, 6, 'ok']],
['regression: stagger base time', ['CP201', 49, 94, 552, 247, 5], [98, 4, 'ok']],
['regression: stagger base time (partial repair)', ['CP778', 179, 65, 525, 61, 0],
[179, 0, 'ok']],
['control 1', ['CP310', 208, 18, 199, 159, 0], [40, 0, 'ok']],
['control 2', ['CP766', 294, 150, 208, 201, 30], [150, 10, 'late']]],
[['boundary: no stagger configured', ['CP7', 100, 50, 400, 60, 0], [100, 0, 'ok']],
['boundary: deadline forces immediate start', ['CP12', 100, 50, 120, 70, 30], [50, 16, 'ok']],
['boundary: tariff already active', ['CP3', 10, 50, 400, 60, 10], [56, 6, 'ok']],
['regression: stagger base time', ['CP321', 7, 32, 498, 89, 15], [41, 9, 'ok']],
['regression: stagger base time (partial repair)', ['CP363', 205, 166, 509, 88, 10],
[209, 4, 'ok']],
['control 1', ['CP883', 235, 120, 211, 80, 5], [131, 4, 'ok']],
['control 2', ['CP742', 19, 177, 199, 247, 10], [177, 3, 'late']]],
[['boundary: no stagger configured', ['CP7', 100, 50, 400, 60, 0], [100, 0, 'ok']],
['boundary: deadline forces immediate start', ['CP12', 100, 50, 120, 70, 30], [50, 16, 'ok']],
['boundary: tariff already active', ['CP3', 10, 50, 400, 60, 10], [56, 6, 'ok']],
['regression: stagger base time', ['CP473', 52, 113, 448, 84, 0], [113, 0, 'ok']],
['regression: stagger base time (partial repair)', ['CP201', 269, 83, 492, 35, 10],
[269, 0, 'ok']],
['control 1', ['CP783', 204, 99, 341, 202, 5], [139, 1, 'ok']],
['control 2', ['CP490', 211, 107, 512, 167, 10], [215, 4, 'ok']]],
[['boundary: no stagger configured', ['CP7', 100, 50, 400, 60, 0], [100, 0, 'ok']],
['boundary: deadline forces immediate start', ['CP12', 100, 50, 120, 70, 30], [50, 16, 'ok']],
['boundary: tariff already active', ['CP3', 10, 50, 400, 60, 10], [56, 6, 'ok']],
['regression: stagger base time', ['CP951', 78, 134, 388, 193, 0], [134, 0, 'ok']],
['regression: stagger base time (partial repair)', ['CP907', 199, 117, 410, 31, 0],
[199, 0, 'ok']],
['control 1', ['CP137', 10, 19, 66, 6, 15], [24, 5, 'ok']],
['control 2', ['CP783', 210, 193, 350, 267, 30], [193, 3, 'late']]],
[['boundary: no stagger configured', ['CP7', 100, 50, 400, 60, 0], [100, 0, 'ok']],
['boundary: deadline forces immediate start', ['CP12', 100, 50, 120, 70, 30], [50, 16, 'ok']],
['boundary: tariff already active', ['CP3', 10, 50, 400, 60, 10], [56, 6, 'ok']],
['regression: stagger base time', ['CP544', 22, 72, 471, 102, 5], [74, 2, 'ok']],
['regression: stagger base time (partial repair)', ['CP353', 241, 118, 320, 150, 5],
[170, 1, 'ok']],
['control 1', ['CP873', 194, 7, 146, 117, 15], [29, 6, 'ok']],
['control 2', ['CP733', 56, 136, 418, 4, 0], [136, 0, 'ok']]]]
for label, args, expected in fixtures[N-1]:
check(label, solve(*args), expected)
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 |
|---|---|---|---|
| boundary: no stagger configured | [100, 0, 'ok'] | [100, 0, 'ok'] | Passed |
| boundary: deadline forces immediate start | [50, 16, 'ok'] | [50, 16, 'ok'] | Passed |
| boundary: tariff already active | [56, 6, 'ok'] | [56, 6, 'ok'] | Passed |
| regression: stagger base time | [98, 4, 'ok'] | [98, 4, 'ok'] | Passed |
| regression: stagger base time (partial repair) | [179, 0, 'ok'] | [179, 0, 'ok'] | Passed |
| control 1 | [40, 0, 'ok'] | [40, 0, 'ok'] | Passed |
| control 2 | [150, 10, 'late'] | [150, 10, 'late'] | Passed |
SHA-256 / e8f8bf5a7742ac4ba8d45987de19ecd8c0d63986f78e0daf45de120fa245bf1d
Verification & scope
Deterministic stipulated toy contract for teaching; no claim of conformance with any standard, vendor protocol or production controller. 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 2026-09-29T14:51:53.808903+00:00.
Case digest / a68572439bfa463636c5afd82389eba0fcbeb82aa5585f0b97a0fa822b730b45