FA-74071 / Feature flag rollout bucketing / Open access

Mutually exclusive layer allocation: Paused experiments release their range · case 01

Pausing an experiment pours its users into an overlapping experiment listed later.

Verified by executionVariant 1 · 8 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

A paused experiment is skipped with continue instead of reserving its range.

VERIFIED REPAIR

Return no experiment for users inside a paused experiment's range.

Unsuccessful approach: Reporting a paused marker name still labels the user as allocated.

Case contract

bucket = int(md5(layer_salt + ":" + user) hex, 16) % 1000. experiments is an ordered list of {name, start, end, paused?} with start/end in percent (one decimal) converted to permille by round(x * 10); ranges are half-open [start, end). The first listed range containing the bucket decides: a paused experiment reserves its range (user gets None). Return [bucket, name or None].

Why this case matters

Layers keep concurrent experiments from overlapping on the same users.

1 / The failure

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json
import hashlib
N = 1
observations = []
def solve(layer_salt, user, experiments):
    bucket = int(hashlib.md5((layer_salt + ':' + user).encode()).hexdigest(), 16) % 1000
    for exp in experiments:
        lo = round(exp['start'] * 10)
        hi = round(exp['end'] * 10)
        if lo <= bucket < hi:
            if exp.get('paused'):
                continue
            return [bucket, exp['name']]
    return [bucket, None]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('bucket at range end belongs to next range',
   ['layer-a', 'alice', [{'name': 'x', 'start': 0, 'end': 98.8}, {'name': 'y', 'start': 98.8, 'end': 100}]],
   [988, 'y']),
  ('bucket at range start is included',
   ['layer-b', 'bob', [{'name': 'x', 'start': 30.9, 'end': 100}]],
   [309, 'x']),
  ('paused range reserves its users',
   ['layer-a',
    'alice',
    [{'name': 'x', 'start': 0, 'end': 100, 'paused': True}, {'name': 'y', 'start': 0, 'end': 100}]],
   [988, None]),
  ('first listed overlapping range wins',
   ['layer-b',
    'bob',
    [{'name': 'wide', 'start': 0, 'end': 100}, {'name': 'narrow', 'start': 30.9, 'end': 31.0}]],
   [309, 'wide']),
  ('percent bounds convert to permille',
   ['layer-a', 'alice', [{'name': 'x', 'start': 98.3, 'end': 99.3}]],
   [988, 'x']),
  ('layer sample 1',
   ['layer-a',
    'u295',
    [{'name': 'exp0', 'start': 50, 'end': 57.7, 'paused': False},
     {'name': 'exp1', 'start': 0, 'end': 57.7, 'paused': False}]],
   [576, 'exp0']),
  ('layer sample 2',
   ['layer-b',
    'u4435',
    [{'name': 'exp0', 'start': 0, 'end': 75.0, 'paused': True},
     {'name': 'exp1', 'start': 0, 'end': 74.9, 'paused': False}]],
   [750, None]),
  ('layer sample 3',
   ['layer-a',
    'u3828',
    [{'name': 'exp0', 'start': 1.72, 'end': 17.3, 'paused': False},
     {'name': 'exp1', 'start': 0, 'end': 17.3, 'paused': True}]],
   [172, 'exp0'])],
 [('bucket at range start is included',
   ['layer-b', 'bob', [{'name': 'x', 'start': 30.9, 'end': 100}]],
   [309, 'x']),
  ('paused range reserves its users',
   ['layer-a',
    'alice',
    [{'name': 'x', 'start': 0, 'end': 100, 'paused': True}, {'name': 'y', 'start': 0, 'end': 100}]],
   [988, None]),
  ('first listed overlapping range wins',
   ['layer-b',
    'bob',
    [{'name': 'wide', 'start': 0, 'end': 100}, {'name': 'narrow', 'start': 30.9, 'end': 31.0}]],
   [309, 'wide']),
  ('percent bounds convert to permille',
   ['layer-a', 'alice', [{'name': 'x', 'start': 98.3, 'end': 99.3}]],
   [988, 'x']),
  ('no range matches', ['layer-b', 'bob', [{'name': 'x', 'start': 0, 'end': 0}]], [309, None]),
  ('layer sample 6',
   ['layer-a', 'u2869', [{'name': 'exp0', 'start': 28.1, 'end': 50, 'paused': False}]],
   [282, 'exp0']),
  ('layer sample 18',
   ['layer-b',
    'u4000',
    [{'name': 'exp0', 'start': 0, 'end': 2.83, 'paused': False},
     {'name': 'exp1', 'start': 0, 'end': 100, 'paused': True},
     {'name': 'exp2', 'start': 28.2, 'end': 28.4, 'paused': False}]],
   [283, None]),
  ('layer sample 34',
   ['layer-b', 'u91', [{'name': 'exp0', 'start': 41.6, 'end': 41.8, 'paused': True}]],
   [417, None])],
 [('paused range reserves its users',
   ['layer-a',
    'alice',
    [{'name': 'x', 'start': 0, 'end': 100, 'paused': True}, {'name': 'y', 'start': 0, 'end': 100}]],
   [988, None]),
  ('first listed overlapping range wins',
   ['layer-b',
    'bob',
    [{'name': 'wide', 'start': 0, 'end': 100}, {'name': 'narrow', 'start': 30.9, 'end': 31.0}]],
   [309, 'wide']),
  ('percent bounds convert to permille',
   ['layer-a', 'alice', [{'name': 'x', 'start': 98.3, 'end': 99.3}]],
   [988, 'x']),
  ('no range matches', ['layer-b', 'bob', [{'name': 'x', 'start': 0, 'end': 0}]], [309, None]),
  ('empty experiment list', ['layer-a', 'carol', []], [970, None]),
  ('layer sample 11',
   ['layer-b',
    'u3995',
    [{'name': 'exp0', 'start': 50, 'end': 84.5, 'paused': True},
     {'name': 'exp1', 'start': 8.45, 'end': 84.5, 'paused': True}]],
   [845, None]),
  ('layer sample 12',
   ['layer-a', 'u3185', [{'name': 'exp0', 'start': 50, 'end': 98.8, 'paused': False}]],
   [344, None]),
  ('layer sample 50',
   ['layer-b',
    'u369',
    [{'name': 'exp0', 'start': 8.27, 'end': 90.0, 'paused': True},
     {'name': 'exp1', 'start': 8.27, 'end': 82.8, 'paused': False}]],
   [827, None])],
 [('bucket at range end belongs to next range',
   ['layer-a', 'alice', [{'name': 'x', 'start': 0, 'end': 98.8}, {'name': 'y', 'start': 98.8, 'end': 100}]],
   [988, 'y']),
  ('first listed overlapping range wins',
   ['layer-b',
    'bob',
    [{'name': 'wide', 'start': 0, 'end': 100}, {'name': 'narrow', 'start': 30.9, 'end': 31.0}]],
   [309, 'wide']),
  ('percent bounds convert to permille',
   ['layer-a', 'alice', [{'name': 'x', 'start': 98.3, 'end': 99.3}]],
   [988, 'x']),
  ('no range matches', ['layer-b', 'bob', [{'name': 'x', 'start': 0, 'end': 0}]], [309, None]),
  ('empty experiment list', ['layer-a', 'carol', []], [970, None]),
  ('layer sample 16',
   ['layer-a',
    'u4745',
    [{'name': 'exp0', 'start': 81.9, 'end': 100, 'paused': True},
     {'name': 'exp1', 'start': 8.19, 'end': 82.0, 'paused': True},
     {'name': 'exp2', 'start': 50, 'end': 82.0, 'paused': False}]],
   [819, None]),
  ('layer sample 17',
   ['layer-a',
    'u1058',
    [{'name': 'exp0', 'start': 39.5, 'end': 100, 'paused': False},
     {'name': 'exp1', 'start': 39.3, 'end': 39.4, 'paused': False}]],
   [394, None]),
  ('layer sample 34',
   ['layer-b', 'u91', [{'name': 'exp0', 'start': 41.6, 'end': 41.8, 'paused': True}]],
   [417, None])],
 [('bucket at range end belongs to next range',
   ['layer-a', 'alice', [{'name': 'x', 'start': 0, 'end': 98.8}, {'name': 'y', 'start': 98.8, 'end': 100}]],
   [988, 'y']),
  ('bucket at range start is included',
   ['layer-b', 'bob', [{'name': 'x', 'start': 30.9, 'end': 100}]],
   [309, 'x']),
  ('paused range reserves its users',
   ['layer-a',
    'alice',
    [{'name': 'x', 'start': 0, 'end': 100, 'paused': True}, {'name': 'y', 'start': 0, 'end': 100}]],
   [988, None]),
  ('percent bounds convert to permille',
   ['layer-a', 'alice', [{'name': 'x', 'start': 98.3, 'end': 99.3}]],
   [988, 'x']),
  ('no range matches', ['layer-b', 'bob', [{'name': 'x', 'start': 0, 'end': 0}]], [309, None]),
  ('empty experiment list', ['layer-a', 'carol', []], [970, None]),
  ('layer sample 21',
   ['layer-a',
    'u505',
    [{'name': 'exp0', 'start': 0, 'end': 100, 'paused': False},
     {'name': 'exp1', 'start': 54.1, 'end': 100, 'paused': False}]],
   [540, 'exp0']),
  ('layer sample 23',
   ['layer-b',
    'u3183',
    [{'name': 'exp0', 'start': 0, 'end': 50, 'paused': True},
     {'name': 'exp1', 'start': 23.6, 'end': 100, 'paused': False},
     {'name': 'exp2', 'start': 23.7, 'end': 50, 'paused': False}]],
   [236, None])]]
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
bucket at range end belongs to next range	`[988, 'y']`	`[988, 'y']`	Passed
bucket at range start is included	`[309, 'x']`	`[309, 'x']`	Passed
paused range reserves its users	`[988, 'y']`	`[988, None]`	Failed
first listed overlapping range wins	`[309, 'wide']`	`[309, 'wide']`	Passed
percent bounds convert to permille	`[988, 'x']`	`[988, 'x']`	Passed
layer sample 1	`[576, 'exp0']`	`[576, 'exp0']`	Passed
layer sample 2	`[750, None]`	`[750, None]`	Passed
layer sample 3	`[172, 'exp0']`	`[172, 'exp0']`	Passed

SHA-256 / 43b5b6ff6839ae2f0b4f96ce74f3985a57eda70f8d44e284e4a7b7e966e48157

2 / The unsuccessful fix

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json
import hashlib
N = 1
observations = []
def solve(layer_salt, user, experiments):
    bucket = int(hashlib.md5((layer_salt + ':' + user).encode()).hexdigest(), 16) % 1000
    for exp in experiments:
        lo = round(exp['start'] * 10)
        hi = round(exp['end'] * 10)
        if lo <= bucket < hi:
            if exp.get('paused'):
                return [bucket, exp['name'] + ':paused']
            return [bucket, exp['name']]
    return [bucket, None]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('bucket at range end belongs to next range',
   ['layer-a', 'alice', [{'name': 'x', 'start': 0, 'end': 98.8}, {'name': 'y', 'start': 98.8, 'end': 100}]],
   [988, 'y']),
  ('bucket at range start is included',
   ['layer-b', 'bob', [{'name': 'x', 'start': 30.9, 'end': 100}]],
   [309, 'x']),
  ('paused range reserves its users',
   ['layer-a',
    'alice',
    [{'name': 'x', 'start': 0, 'end': 100, 'paused': True}, {'name': 'y', 'start': 0, 'end': 100}]],
   [988, None]),
  ('first listed overlapping range wins',
   ['layer-b',
    'bob',
    [{'name': 'wide', 'start': 0, 'end': 100}, {'name': 'narrow', 'start': 30.9, 'end': 31.0}]],
   [309, 'wide']),
  ('percent bounds convert to permille',
   ['layer-a', 'alice', [{'name': 'x', 'start': 98.3, 'end': 99.3}]],
   [988, 'x']),
  ('layer sample 1',
   ['layer-a',
    'u295',
    [{'name': 'exp0', 'start': 50, 'end': 57.7, 'paused': False},
     {'name': 'exp1', 'start': 0, 'end': 57.7, 'paused': False}]],
   [576, 'exp0']),
  ('layer sample 2',
   ['layer-b',
    'u4435',
    [{'name': 'exp0', 'start': 0, 'end': 75.0, 'paused': True},
     {'name': 'exp1', 'start': 0, 'end': 74.9, 'paused': False}]],
   [750, None]),
  ('layer sample 3',
   ['layer-a',
    'u3828',
    [{'name': 'exp0', 'start': 1.72, 'end': 17.3, 'paused': False},
     {'name': 'exp1', 'start': 0, 'end': 17.3, 'paused': True}]],
   [172, 'exp0'])],
 [('bucket at range start is included',
   ['layer-b', 'bob', [{'name': 'x', 'start': 30.9, 'end': 100}]],
   [309, 'x']),
  ('paused range reserves its users',
   ['layer-a',
    'alice',
    [{'name': 'x', 'start': 0, 'end': 100, 'paused': True}, {'name': 'y', 'start': 0, 'end': 100}]],
   [988, None]),
  ('first listed overlapping range wins',
   ['layer-b',
    'bob',
    [{'name': 'wide', 'start': 0, 'end': 100}, {'name': 'narrow', 'start': 30.9, 'end': 31.0}]],
   [309, 'wide']),
  ('percent bounds convert to permille',
   ['layer-a', 'alice', [{'name': 'x', 'start': 98.3, 'end': 99.3}]],
   [988, 'x']),
  ('no range matches', ['layer-b', 'bob', [{'name': 'x', 'start': 0, 'end': 0}]], [309, None]),
  ('layer sample 6',
   ['layer-a', 'u2869', [{'name': 'exp0', 'start': 28.1, 'end': 50, 'paused': False}]],
   [282, 'exp0']),
  ('layer sample 18',
   ['layer-b',
    'u4000',
    [{'name': 'exp0', 'start': 0, 'end': 2.83, 'paused': False},
     {'name': 'exp1', 'start': 0, 'end': 100, 'paused': True},
     {'name': 'exp2', 'start': 28.2, 'end': 28.4, 'paused': False}]],
   [283, None]),
  ('layer sample 34',
   ['layer-b', 'u91', [{'name': 'exp0', 'start': 41.6, 'end': 41.8, 'paused': True}]],
   [417, None])],
 [('paused range reserves its users',
   ['layer-a',
    'alice',
    [{'name': 'x', 'start': 0, 'end': 100, 'paused': True}, {'name': 'y', 'start': 0, 'end': 100}]],
   [988, None]),
  ('first listed overlapping range wins',
   ['layer-b',
    'bob',
    [{'name': 'wide', 'start': 0, 'end': 100}, {'name': 'narrow', 'start': 30.9, 'end': 31.0}]],
   [309, 'wide']),
  ('percent bounds convert to permille',
   ['layer-a', 'alice', [{'name': 'x', 'start': 98.3, 'end': 99.3}]],
   [988, 'x']),
  ('no range matches', ['layer-b', 'bob', [{'name': 'x', 'start': 0, 'end': 0}]], [309, None]),
  ('empty experiment list', ['layer-a', 'carol', []], [970, None]),
  ('layer sample 11',
   ['layer-b',
    'u3995',
    [{'name': 'exp0', 'start': 50, 'end': 84.5, 'paused': True},
     {'name': 'exp1', 'start': 8.45, 'end': 84.5, 'paused': True}]],
   [845, None]),
  ('layer sample 12',
   ['layer-a', 'u3185', [{'name': 'exp0', 'start': 50, 'end': 98.8, 'paused': False}]],
   [344, None]),
  ('layer sample 50',
   ['layer-b',
    'u369',
    [{'name': 'exp0', 'start': 8.27, 'end': 90.0, 'paused': True},
     {'name': 'exp1', 'start': 8.27, 'end': 82.8, 'paused': False}]],
   [827, None])],
 [('bucket at range end belongs to next range',
   ['layer-a', 'alice', [{'name': 'x', 'start': 0, 'end': 98.8}, {'name': 'y', 'start': 98.8, 'end': 100}]],
   [988, 'y']),
  ('first listed overlapping range wins',
   ['layer-b',
    'bob',
    [{'name': 'wide', 'start': 0, 'end': 100}, {'name': 'narrow', 'start': 30.9, 'end': 31.0}]],
   [309, 'wide']),
  ('percent bounds convert to permille',
   ['layer-a', 'alice', [{'name': 'x', 'start': 98.3, 'end': 99.3}]],
   [988, 'x']),
  ('no range matches', ['layer-b', 'bob', [{'name': 'x', 'start': 0, 'end': 0}]], [309, None]),
  ('empty experiment list', ['layer-a', 'carol', []], [970, None]),
  ('layer sample 16',
   ['layer-a',
    'u4745',
    [{'name': 'exp0', 'start': 81.9, 'end': 100, 'paused': True},
     {'name': 'exp1', 'start': 8.19, 'end': 82.0, 'paused': True},
     {'name': 'exp2', 'start': 50, 'end': 82.0, 'paused': False}]],
   [819, None]),
  ('layer sample 17',
   ['layer-a',
    'u1058',
    [{'name': 'exp0', 'start': 39.5, 'end': 100, 'paused': False},
     {'name': 'exp1', 'start': 39.3, 'end': 39.4, 'paused': False}]],
   [394, None]),
  ('layer sample 34',
   ['layer-b', 'u91', [{'name': 'exp0', 'start': 41.6, 'end': 41.8, 'paused': True}]],
   [417, None])],
 [('bucket at range end belongs to next range',
   ['layer-a', 'alice', [{'name': 'x', 'start': 0, 'end': 98.8}, {'name': 'y', 'start': 98.8, 'end': 100}]],
   [988, 'y']),
  ('bucket at range start is included',
   ['layer-b', 'bob', [{'name': 'x', 'start': 30.9, 'end': 100}]],
   [309, 'x']),
  ('paused range reserves its users',
   ['layer-a',
    'alice',
    [{'name': 'x', 'start': 0, 'end': 100, 'paused': True}, {'name': 'y', 'start': 0, 'end': 100}]],
   [988, None]),
  ('percent bounds convert to permille',
   ['layer-a', 'alice', [{'name': 'x', 'start': 98.3, 'end': 99.3}]],
   [988, 'x']),
  ('no range matches', ['layer-b', 'bob', [{'name': 'x', 'start': 0, 'end': 0}]], [309, None]),
  ('empty experiment list', ['layer-a', 'carol', []], [970, None]),
  ('layer sample 21',
   ['layer-a',
    'u505',
    [{'name': 'exp0', 'start': 0, 'end': 100, 'paused': False},
     {'name': 'exp1', 'start': 54.1, 'end': 100, 'paused': False}]],
   [540, 'exp0']),
  ('layer sample 23',
   ['layer-b',
    'u3183',
    [{'name': 'exp0', 'start': 0, 'end': 50, 'paused': True},
     {'name': 'exp1', 'start': 23.6, 'end': 100, 'paused': False},
     {'name': 'exp2', 'start': 23.7, 'end': 50, 'paused': False}]],
   [236, None])]]
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
bucket at range end belongs to next range	`[988, 'y']`	`[988, 'y']`	Passed
bucket at range start is included	`[309, 'x']`	`[309, 'x']`	Passed
paused range reserves its users	`[988, 'x:paused']`	`[988, None]`	Failed
first listed overlapping range wins	`[309, 'wide']`	`[309, 'wide']`	Passed
percent bounds convert to permille	`[988, 'x']`	`[988, 'x']`	Passed
layer sample 1	`[576, 'exp0']`	`[576, 'exp0']`	Passed
layer sample 2	`[750, None]`	`[750, None]`	Passed
layer sample 3	`[172, 'exp0']`	`[172, 'exp0']`	Passed

SHA-256 / d75fba5ba5c8220aca07e83bd152e68e6892dd451d964dbc9312df160662aae1

3 / The verified repair

Exit 0

"""Failure Map reference implementation. Python standard library only."""
import json
import hashlib
N = 1
observations = []
def solve(layer_salt, user, experiments):
    bucket = int(hashlib.md5((layer_salt + ':' + user).encode()).hexdigest(), 16) % 1000
    for exp in experiments:
        lo = round(exp['start'] * 10)
        hi = round(exp['end'] * 10)
        if lo <= bucket < hi:
            if exp.get('paused'):
                return [bucket, None]
            return [bucket, exp['name']]
    return [bucket, None]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('bucket at range end belongs to next range',
   ['layer-a', 'alice', [{'name': 'x', 'start': 0, 'end': 98.8}, {'name': 'y', 'start': 98.8, 'end': 100}]],
   [988, 'y']),
  ('bucket at range start is included',
   ['layer-b', 'bob', [{'name': 'x', 'start': 30.9, 'end': 100}]],
   [309, 'x']),
  ('paused range reserves its users',
   ['layer-a',
    'alice',
    [{'name': 'x', 'start': 0, 'end': 100, 'paused': True}, {'name': 'y', 'start': 0, 'end': 100}]],
   [988, None]),
  ('first listed overlapping range wins',
   ['layer-b',
    'bob',
    [{'name': 'wide', 'start': 0, 'end': 100}, {'name': 'narrow', 'start': 30.9, 'end': 31.0}]],
   [309, 'wide']),
  ('percent bounds convert to permille',
   ['layer-a', 'alice', [{'name': 'x', 'start': 98.3, 'end': 99.3}]],
   [988, 'x']),
  ('layer sample 1',
   ['layer-a',
    'u295',
    [{'name': 'exp0', 'start': 50, 'end': 57.7, 'paused': False},
     {'name': 'exp1', 'start': 0, 'end': 57.7, 'paused': False}]],
   [576, 'exp0']),
  ('layer sample 2',
   ['layer-b',
    'u4435',
    [{'name': 'exp0', 'start': 0, 'end': 75.0, 'paused': True},
     {'name': 'exp1', 'start': 0, 'end': 74.9, 'paused': False}]],
   [750, None]),
  ('layer sample 3',
   ['layer-a',
    'u3828',
    [{'name': 'exp0', 'start': 1.72, 'end': 17.3, 'paused': False},
     {'name': 'exp1', 'start': 0, 'end': 17.3, 'paused': True}]],
   [172, 'exp0'])],
 [('bucket at range start is included',
   ['layer-b', 'bob', [{'name': 'x', 'start': 30.9, 'end': 100}]],
   [309, 'x']),
  ('paused range reserves its users',
   ['layer-a',
    'alice',
    [{'name': 'x', 'start': 0, 'end': 100, 'paused': True}, {'name': 'y', 'start': 0, 'end': 100}]],
   [988, None]),
  ('first listed overlapping range wins',
   ['layer-b',
    'bob',
    [{'name': 'wide', 'start': 0, 'end': 100}, {'name': 'narrow', 'start': 30.9, 'end': 31.0}]],
   [309, 'wide']),
  ('percent bounds convert to permille',
   ['layer-a', 'alice', [{'name': 'x', 'start': 98.3, 'end': 99.3}]],
   [988, 'x']),
  ('no range matches', ['layer-b', 'bob', [{'name': 'x', 'start': 0, 'end': 0}]], [309, None]),
  ('layer sample 6',
   ['layer-a', 'u2869', [{'name': 'exp0', 'start': 28.1, 'end': 50, 'paused': False}]],
   [282, 'exp0']),
  ('layer sample 18',
   ['layer-b',
    'u4000',
    [{'name': 'exp0', 'start': 0, 'end': 2.83, 'paused': False},
     {'name': 'exp1', 'start': 0, 'end': 100, 'paused': True},
     {'name': 'exp2', 'start': 28.2, 'end': 28.4, 'paused': False}]],
   [283, None]),
  ('layer sample 34',
   ['layer-b', 'u91', [{'name': 'exp0', 'start': 41.6, 'end': 41.8, 'paused': True}]],
   [417, None])],
 [('paused range reserves its users',
   ['layer-a',
    'alice',
    [{'name': 'x', 'start': 0, 'end': 100, 'paused': True}, {'name': 'y', 'start': 0, 'end': 100}]],
   [988, None]),
  ('first listed overlapping range wins',
   ['layer-b',
    'bob',
    [{'name': 'wide', 'start': 0, 'end': 100}, {'name': 'narrow', 'start': 30.9, 'end': 31.0}]],
   [309, 'wide']),
  ('percent bounds convert to permille',
   ['layer-a', 'alice', [{'name': 'x', 'start': 98.3, 'end': 99.3}]],
   [988, 'x']),
  ('no range matches', ['layer-b', 'bob', [{'name': 'x', 'start': 0, 'end': 0}]], [309, None]),
  ('empty experiment list', ['layer-a', 'carol', []], [970, None]),
  ('layer sample 11',
   ['layer-b',
    'u3995',
    [{'name': 'exp0', 'start': 50, 'end': 84.5, 'paused': True},
     {'name': 'exp1', 'start': 8.45, 'end': 84.5, 'paused': True}]],
   [845, None]),
  ('layer sample 12',
   ['layer-a', 'u3185', [{'name': 'exp0', 'start': 50, 'end': 98.8, 'paused': False}]],
   [344, None]),
  ('layer sample 50',
   ['layer-b',
    'u369',
    [{'name': 'exp0', 'start': 8.27, 'end': 90.0, 'paused': True},
     {'name': 'exp1', 'start': 8.27, 'end': 82.8, 'paused': False}]],
   [827, None])],
 [('bucket at range end belongs to next range',
   ['layer-a', 'alice', [{'name': 'x', 'start': 0, 'end': 98.8}, {'name': 'y', 'start': 98.8, 'end': 100}]],
   [988, 'y']),
  ('first listed overlapping range wins',
   ['layer-b',
    'bob',
    [{'name': 'wide', 'start': 0, 'end': 100}, {'name': 'narrow', 'start': 30.9, 'end': 31.0}]],
   [309, 'wide']),
  ('percent bounds convert to permille',
   ['layer-a', 'alice', [{'name': 'x', 'start': 98.3, 'end': 99.3}]],
   [988, 'x']),
  ('no range matches', ['layer-b', 'bob', [{'name': 'x', 'start': 0, 'end': 0}]], [309, None]),
  ('empty experiment list', ['layer-a', 'carol', []], [970, None]),
  ('layer sample 16',
   ['layer-a',
    'u4745',
    [{'name': 'exp0', 'start': 81.9, 'end': 100, 'paused': True},
     {'name': 'exp1', 'start': 8.19, 'end': 82.0, 'paused': True},
     {'name': 'exp2', 'start': 50, 'end': 82.0, 'paused': False}]],
   [819, None]),
  ('layer sample 17',
   ['layer-a',
    'u1058',
    [{'name': 'exp0', 'start': 39.5, 'end': 100, 'paused': False},
     {'name': 'exp1', 'start': 39.3, 'end': 39.4, 'paused': False}]],
   [394, None]),
  ('layer sample 34',
   ['layer-b', 'u91', [{'name': 'exp0', 'start': 41.6, 'end': 41.8, 'paused': True}]],
   [417, None])],
 [('bucket at range end belongs to next range',
   ['layer-a', 'alice', [{'name': 'x', 'start': 0, 'end': 98.8}, {'name': 'y', 'start': 98.8, 'end': 100}]],
   [988, 'y']),
  ('bucket at range start is included',
   ['layer-b', 'bob', [{'name': 'x', 'start': 30.9, 'end': 100}]],
   [309, 'x']),
  ('paused range reserves its users',
   ['layer-a',
    'alice',
    [{'name': 'x', 'start': 0, 'end': 100, 'paused': True}, {'name': 'y', 'start': 0, 'end': 100}]],
   [988, None]),
  ('percent bounds convert to permille',
   ['layer-a', 'alice', [{'name': 'x', 'start': 98.3, 'end': 99.3}]],
   [988, 'x']),
  ('no range matches', ['layer-b', 'bob', [{'name': 'x', 'start': 0, 'end': 0}]], [309, None]),
  ('empty experiment list', ['layer-a', 'carol', []], [970, None]),
  ('layer sample 21',
   ['layer-a',
    'u505',
    [{'name': 'exp0', 'start': 0, 'end': 100, 'paused': False},
     {'name': 'exp1', 'start': 54.1, 'end': 100, 'paused': False}]],
   [540, 'exp0']),
  ('layer sample 23',
   ['layer-b',
    'u3183',
    [{'name': 'exp0', 'start': 0, 'end': 50, 'paused': True},
     {'name': 'exp1', 'start': 23.6, 'end': 100, 'paused': False},
     {'name': 'exp2', 'start': 23.7, 'end': 50, 'paused': False}]],
   [236, None])]]
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
bucket at range end belongs to next range	`[988, 'y']`	`[988, 'y']`	Passed
bucket at range start is included	`[309, 'x']`	`[309, 'x']`	Passed
paused range reserves its users	`[988, None]`	`[988, None]`	Passed
first listed overlapping range wins	`[309, 'wide']`	`[309, 'wide']`	Passed
percent bounds convert to permille	`[988, 'x']`	`[988, 'x']`	Passed
layer sample 1	`[576, 'exp0']`	`[576, 'exp0']`	Passed
layer sample 2	`[750, None]`	`[750, None]`	Passed
layer sample 3	`[172, 'exp0']`	`[172, 'exp0']`	Passed

SHA-256 / d667c550ef131eadf04eb52abed74bcf2182e1cf0f05b172f8aa720df057ea29

Verification & scope

A deterministic toy flag-evaluation model with a stipulated contract; it does not reproduce any vendor SDK byte for byte. 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 2026-09-29T14:48:53.247649+00:00.

Case digest / 392332a94d6e4c17b0374625993fac47289088b6aed6d3f8d489c95c93552fd4