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FA-24441 / Client state / Open access

Keyed component instance reconciliation: New instance mounts · case 01

New instance mounts.

Verified by executionVariant 1 · 70 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

The new-instance-mounts client decision evaluates `[k for k,t in incoming if k not in dict(old)]` instead of `[k for k,t in incoming if (k,t) not in old]`.

THE FAILURE

The new-instance-mounts client decision evaluates `[k for k,t in incoming if k not in dict(old)]` instead of `[k for k,t in incoming if (k,t) not in old]`.

Unsuccessful approach: The partial repair `[k for k,t in incoming]` still violates the explicit fixture contract.

Case contract

A component instance is identified by sibling key plus component type. Reordering preserves its state, changing type remounts, removed keys lose state, and replacement cleanup happens before mount. Operation new-instance-mounts has the six explicit input/output oracles below.

Why this case matters

An offline client lifecycle model that isolates a state-management defect without DOM rendering or network services.

1 / The failure

Exit 1
"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(operation, s):
    old, incoming, state = s
    if operation == 'type-and-key-reuse':
        return [k for k,t in incoming if (k,t) in old]
    if operation == 'new-instance-mounts':
        return [k for k,t in incoming if k not in dict(old)]
    if operation == 'old-instance-unmounts':
        return [k for k,t in old if (k,t) not in incoming]
    if operation == 'state-follows-key-through-reorder':
        return [state.get(k) for k,t in incoming if (k,t) in old]
    if operation == 'render-order-follows-incoming':
        return [k for k,t in incoming]
    if operation == 'changed-type-state-reset':
        return {k:state.get(k) if (k,t) in old else None for k,t in incoming}
    if operation == 'cleanup-before-replacement-mount':
        return [(k,'cleanup') for k,t in old if k in dict(incoming) and (k,t) not in incoming]+[(k,'mount') for k,t in incoming if k in dict(old) and (k,t) not in old]
    if operation == 'removed-state-pruning':
        return {k:v for k,v in state.items() if k in dict(incoming)}
    if operation == 'insertion-position':
        return {k:i for i,(k,t) in enumerate(incoming)}
    if operation == 'retained-instance-moves':
        return [k for i,(k,t) in enumerate(incoming) if (k,t) in old and old.index((k,t))!=i]
    raise ValueError('unknown modeled operation')
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('type-and-key-reuse scenario 1', solve('type-and-key-reuse', ([('a','card'),('b','card')],[('b','card'),('a','card')],{'a':N,'b':2})), ['b','a'])
check('type-and-key-reuse scenario 2', solve('type-and-key-reuse', ([], [('a','card')],{})), [])
check('type-and-key-reuse scenario 3', solve('type-and-key-reuse', ([('a','card')],[('a','panel')],{'a':0})), [])
check('type-and-key-reuse scenario 4', solve('type-and-key-reuse', ([('a','card'),('b','panel')],[('b','panel')],{'a':1,'b':None})), ['b'])
check('type-and-key-reuse scenario 5', solve('type-and-key-reuse', ([('a','card')],[],{'a':N})), [])
check('type-and-key-reuse scenario 6', solve('type-and-key-reuse', ([('a','card')],[('a','card'),('b','card')],{'a':False})), ['a'])
check('new-instance-mounts scenario 1', solve('new-instance-mounts', ([('a','card'),('b','card')],[('b','card'),('a','card')],{'a':N,'b':2})), [])
check('new-instance-mounts scenario 2', solve('new-instance-mounts', ([], [('a','card')],{})), ['a'])
check('new-instance-mounts scenario 3', solve('new-instance-mounts', ([('a','card')],[('a','panel')],{'a':0})), ['a'])
check('new-instance-mounts scenario 4', solve('new-instance-mounts', ([('a','card'),('b','panel')],[('b','panel')],{'a':1,'b':None})), [])
check('new-instance-mounts scenario 5', solve('new-instance-mounts', ([('a','card')],[],{'a':N})), [])
check('new-instance-mounts scenario 6', solve('new-instance-mounts', ([('a','card')],[('a','card'),('b','card')],{'a':False})), ['b'])
check('old-instance-unmounts scenario 1', solve('old-instance-unmounts', ([('a','card'),('b','card')],[('b','card'),('a','card')],{'a':N,'b':2})), [])
check('old-instance-unmounts scenario 2', solve('old-instance-unmounts', ([], [('a','card')],{})), [])
check('old-instance-unmounts scenario 3', solve('old-instance-unmounts', ([('a','card')],[('a','panel')],{'a':0})), ['a'])
check('old-instance-unmounts scenario 4', solve('old-instance-unmounts', ([('a','card'),('b','panel')],[('b','panel')],{'a':1,'b':None})), ['a'])
check('old-instance-unmounts scenario 5', solve('old-instance-unmounts', ([('a','card')],[],{'a':N})), ['a'])
check('old-instance-unmounts scenario 6', solve('old-instance-unmounts', ([('a','card')],[('a','card'),('b','card')],{'a':False})), [])
check('state-follows-key-through-reorder scenario 1', solve('state-follows-key-through-reorder', ([('a','card'),('b','card')],[('b','card'),('a','card')],{'a':N,'b':2})), [2,N])
check('state-follows-key-through-reorder scenario 2', solve('state-follows-key-through-reorder', ([], [('a','card')],{})), [])
check('state-follows-key-through-reorder scenario 3', solve('state-follows-key-through-reorder', ([('a','card')],[('a','panel')],{'a':0})), [])
check('state-follows-key-through-reorder scenario 4', solve('state-follows-key-through-reorder', ([('a','card'),('b','panel')],[('b','panel')],{'a':1,'b':None})), [None])
check('state-follows-key-through-reorder scenario 5', solve('state-follows-key-through-reorder', ([('a','card')],[],{'a':N})), [])
check('state-follows-key-through-reorder scenario 6', solve('state-follows-key-through-reorder', ([('a','card')],[('a','card'),('b','card')],{'a':False})), [False])
check('render-order-follows-incoming scenario 1', solve('render-order-follows-incoming', ([('a','card'),('b','card')],[('b','card'),('a','card')],{'a':N,'b':2})), ['b','a'])
check('render-order-follows-incoming scenario 2', solve('render-order-follows-incoming', ([], [('a','card')],{})), ['a'])
check('render-order-follows-incoming scenario 3', solve('render-order-follows-incoming', ([('a','card')],[('a','panel')],{'a':0})), ['a'])
check('render-order-follows-incoming scenario 4', solve('render-order-follows-incoming', ([('a','card'),('b','panel')],[('b','panel')],{'a':1,'b':None})), ['b'])
check('render-order-follows-incoming scenario 5', solve('render-order-follows-incoming', ([('a','card')],[],{'a':N})), [])
check('render-order-follows-incoming scenario 6', solve('render-order-follows-incoming', ([('a','card')],[('a','card'),('b','card')],{'a':False})), ['a','b'])
check('changed-type-state-reset scenario 1', solve('changed-type-state-reset', ([('a','card'),('b','card')],[('b','card'),('a','card')],{'a':N,'b':2})), {'b':2,'a':N})
check('changed-type-state-reset scenario 2', solve('changed-type-state-reset', ([], [('a','card')],{})), {'a':None})
check('changed-type-state-reset scenario 3', solve('changed-type-state-reset', ([('a','card')],[('a','panel')],{'a':0})), {'a':None})
check('changed-type-state-reset scenario 4', solve('changed-type-state-reset', ([('a','card'),('b','panel')],[('b','panel')],{'a':1,'b':None})), {'b':None})
check('changed-type-state-reset scenario 5', solve('changed-type-state-reset', ([('a','card')],[],{'a':N})), {})
check('changed-type-state-reset scenario 6', solve('changed-type-state-reset', ([('a','card')],[('a','card'),('b','card')],{'a':False})), {'a':False,'b':None})
check('cleanup-before-replacement-mount scenario 1', solve('cleanup-before-replacement-mount', ([('a','card'),('b','card')],[('b','card'),('a','card')],{'a':N,'b':2})), [])
check('cleanup-before-replacement-mount scenario 2', solve('cleanup-before-replacement-mount', ([], [('a','card')],{})), [])
check('cleanup-before-replacement-mount scenario 3', solve('cleanup-before-replacement-mount', ([('a','card')],[('a','panel')],{'a':0})), [('a','cleanup'),('a','mount')])
check('cleanup-before-replacement-mount scenario 4', solve('cleanup-before-replacement-mount', ([('a','card'),('b','panel')],[('b','panel')],{'a':1,'b':None})), [])
check('cleanup-before-replacement-mount scenario 5', solve('cleanup-before-replacement-mount', ([('a','card')],[],{'a':N})), [])
check('cleanup-before-replacement-mount scenario 6', solve('cleanup-before-replacement-mount', ([('a','card')],[('a','card'),('b','card')],{'a':False})), [])
check('removed-state-pruning scenario 1', solve('removed-state-pruning', ([('a','card'),('b','card')],[('b','card'),('a','card')],{'a':N,'b':2})), {'a':N,'b':2})
check('removed-state-pruning scenario 2', solve('removed-state-pruning', ([], [('a','card')],{})), {})
check('removed-state-pruning scenario 3', solve('removed-state-pruning', ([('a','card')],[('a','panel')],{'a':0})), {'a':0})
check('removed-state-pruning scenario 4', solve('removed-state-pruning', ([('a','card'),('b','panel')],[('b','panel')],{'a':1,'b':None})), {'b':None})
check('removed-state-pruning scenario 5', solve('removed-state-pruning', ([('a','card')],[],{'a':N})), {})
check('removed-state-pruning scenario 6', solve('removed-state-pruning', ([('a','card')],[('a','card'),('b','card')],{'a':False})), {'a':False})
check('insertion-position scenario 1', solve('insertion-position', ([('a','card'),('b','card')],[('b','card'),('a','card')],{'a':N,'b':2})), {'b':0,'a':1})
check('insertion-position scenario 2', solve('insertion-position', ([], [('a','card')],{})), {'a':0})
check('insertion-position scenario 3', solve('insertion-position', ([('a','card')],[('a','panel')],{'a':0})), {'a':0})
check('insertion-position scenario 4', solve('insertion-position', ([('a','card'),('b','panel')],[('b','panel')],{'a':1,'b':None})), {'b':0})
check('insertion-position scenario 5', solve('insertion-position', ([('a','card')],[],{'a':N})), {})
check('insertion-position scenario 6', solve('insertion-position', ([('a','card')],[('a','card'),('b','card')],{'a':False})), {'a':0,'b':1})
check('retained-instance-moves scenario 1', solve('retained-instance-moves', ([('a','card'),('b','card')],[('b','card'),('a','card')],{'a':N,'b':2})), ['b','a'])
check('retained-instance-moves scenario 2', solve('retained-instance-moves', ([], [('a','card')],{})), [])
check('retained-instance-moves scenario 3', solve('retained-instance-moves', ([('a','card')],[('a','panel')],{'a':0})), [])
check('retained-instance-moves scenario 4', solve('retained-instance-moves', ([('a','card'),('b','panel')],[('b','panel')],{'a':1,'b':None})), ['b'])
check('retained-instance-moves scenario 5', solve('retained-instance-moves', ([('a','card')],[],{'a':N})), [])
check('retained-instance-moves scenario 6', solve('retained-instance-moves', ([('a','card')],[('a','card'),('b','card')],{'a':False})), [])
check('reordering distinct state values for every seed: type-and-key-reuse', solve('type-and-key-reuse', ([('a','card'),('b','card')],[('b','card'),('a','card')],{'a':N+10,'b':2})), ['b','a'])
check('reordering distinct state values for every seed: new-instance-mounts', solve('new-instance-mounts', ([('a','card'),('b','card')],[('b','card'),('a','card')],{'a':N+10,'b':2})), [])
check('reordering distinct state values for every seed: old-instance-unmounts', solve('old-instance-unmounts', ([('a','card'),('b','card')],[('b','card'),('a','card')],{'a':N+10,'b':2})), [])
check('reordering distinct state values for every seed: state-follows-key-through-reorder', solve('state-follows-key-through-reorder', ([('a','card'),('b','card')],[('b','card'),('a','card')],{'a':N+10,'b':2})), [2,N+10])
check('reordering distinct state values for every seed: render-order-follows-incoming', solve('render-order-follows-incoming', ([('a','card'),('b','card')],[('b','card'),('a','card')],{'a':N+10,'b':2})), ['b','a'])
check('reordering distinct state values for every seed: changed-type-state-reset', solve('changed-type-state-reset', ([('a','card'),('b','card')],[('b','card'),('a','card')],{'a':N+10,'b':2})), {'b':2,'a':N+10})
check('reordering distinct state values for every seed: cleanup-before-replacement-mount', solve('cleanup-before-replacement-mount', ([('a','card'),('b','card')],[('b','card'),('a','card')],{'a':N+10,'b':2})), [])
check('reordering distinct state values for every seed: removed-state-pruning', solve('removed-state-pruning', ([('a','card'),('b','card')],[('b','card'),('a','card')],{'a':N+10,'b':2})), {'a':N+10,'b':2})
check('reordering distinct state values for every seed: insertion-position', solve('insertion-position', ([('a','card'),('b','card')],[('b','card'),('a','card')],{'a':N+10,'b':2})), {'b':0,'a':1})
check('reordering distinct state values for every seed: retained-instance-moves', solve('retained-instance-moves', ([('a','card'),('b','card')],[('b','card'),('a','card')],{'a':N+10,'b':2})), ['b','a'])
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 fixtureActualExpectedOutcome
type-and-key-reuse scenario 1['b', 'a']['b', 'a']Passed
type-and-key-reuse scenario 2[][]Passed
type-and-key-reuse scenario 3[][]Passed
type-and-key-reuse scenario 4['b']['b']Passed
type-and-key-reuse scenario 5[][]Passed
type-and-key-reuse scenario 6['a']['a']Passed
new-instance-mounts scenario 1[][]Passed
new-instance-mounts scenario 2['a']['a']Passed
new-instance-mounts scenario 3[]['a']Failed
new-instance-mounts scenario 4[][]Passed
new-instance-mounts scenario 5[][]Passed
new-instance-mounts scenario 6['b']['b']Passed
old-instance-unmounts scenario 1[][]Passed
old-instance-unmounts scenario 2[][]Passed
old-instance-unmounts scenario 3['a']['a']Passed
old-instance-unmounts scenario 4['a']['a']Passed
old-instance-unmounts scenario 5['a']['a']Passed
old-instance-unmounts scenario 6[][]Passed
state-follows-key-through-reorder scenario 1[2, 1][2, 1]Passed
state-follows-key-through-reorder scenario 2[][]Passed
state-follows-key-through-reorder scenario 3[][]Passed
state-follows-key-through-reorder scenario 4[None][None]Passed
state-follows-key-through-reorder scenario 5[][]Passed
state-follows-key-through-reorder scenario 6[False][False]Passed
render-order-follows-incoming scenario 1['b', 'a']['b', 'a']Passed
render-order-follows-incoming scenario 2['a']['a']Passed
render-order-follows-incoming scenario 3['a']['a']Passed
render-order-follows-incoming scenario 4['b']['b']Passed
render-order-follows-incoming scenario 5[][]Passed
render-order-follows-incoming scenario 6['a', 'b']['a', 'b']Passed
changed-type-state-reset scenario 1{'a': 1, 'b': 2}{'a': 1, 'b': 2}Passed
changed-type-state-reset scenario 2{'a': None}{'a': None}Passed
changed-type-state-reset scenario 3{'a': None}{'a': None}Passed
changed-type-state-reset scenario 4{'b': None}{'b': None}Passed
changed-type-state-reset scenario 5{}{}Passed
changed-type-state-reset scenario 6{'a': False, 'b': None}{'a': False, 'b': None}Passed
cleanup-before-replacement-mount scenario 1[][]Passed
cleanup-before-replacement-mount scenario 2[][]Passed
cleanup-before-replacement-mount scenario 3[['a', 'cleanup'], ['a', 'mount']][['a', 'cleanup'], ['a', 'mount']]Passed
cleanup-before-replacement-mount scenario 4[][]Passed
cleanup-before-replacement-mount scenario 5[][]Passed
cleanup-before-replacement-mount scenario 6[][]Passed
removed-state-pruning scenario 1{'a': 1, 'b': 2}{'a': 1, 'b': 2}Passed
removed-state-pruning scenario 2{}{}Passed
removed-state-pruning scenario 3{'a': 0}{'a': 0}Passed
removed-state-pruning scenario 4{'b': None}{'b': None}Passed
removed-state-pruning scenario 5{}{}Passed
removed-state-pruning scenario 6{'a': False}{'a': False}Passed
insertion-position scenario 1{'a': 1, 'b': 0}{'a': 1, 'b': 0}Passed
insertion-position scenario 2{'a': 0}{'a': 0}Passed
insertion-position scenario 3{'a': 0}{'a': 0}Passed
insertion-position scenario 4{'b': 0}{'b': 0}Passed
insertion-position scenario 5{}{}Passed
insertion-position scenario 6{'a': 0, 'b': 1}{'a': 0, 'b': 1}Passed
retained-instance-moves scenario 1['b', 'a']['b', 'a']Passed
retained-instance-moves scenario 2[][]Passed
retained-instance-moves scenario 3[][]Passed
retained-instance-moves scenario 4['b']['b']Passed
retained-instance-moves scenario 5[][]Passed
retained-instance-moves scenario 6[][]Passed
reordering distinct state values for every seed: type-and-key-reuse['b', 'a']['b', 'a']Passed
reordering distinct state values for every seed: new-instance-mounts[][]Passed
reordering distinct state values for every seed: old-instance-unmounts[][]Passed
reordering distinct state values for every seed: state-follows-key-through-reorder[2, 11][2, 11]Passed
reordering distinct state values for every seed: render-order-follows-incoming['b', 'a']['b', 'a']Passed
reordering distinct state values for every seed: changed-type-state-reset{'a': 11, 'b': 2}{'a': 11, 'b': 2}Passed
reordering distinct state values for every seed: cleanup-before-replacement-mount[][]Passed
reordering distinct state values for every seed: removed-state-pruning{'a': 11, 'b': 2}{'a': 11, 'b': 2}Passed
reordering distinct state values for every seed: insertion-position{'a': 1, 'b': 0}{'a': 1, 'b': 0}Passed
reordering distinct state values for every seed: retained-instance-moves['b', 'a']['b', 'a']Passed

SHA-256 / e02df52ece7f8c11d5c2b46a7c5be9709228f294ea5dd59ab6a99192b7743d21

2 / The unsuccessful fix

Exit 1
"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(operation, s):
    old, incoming, state = s
    if operation == 'type-and-key-reuse':
        return [k for k,t in incoming if (k,t) in old]
    if operation == 'new-instance-mounts':
        return [k for k,t in incoming]
    if operation == 'old-instance-unmounts':
        return [k for k,t in old if (k,t) not in incoming]
    if operation == 'state-follows-key-through-reorder':
        return [state.get(k) for k,t in incoming if (k,t) in old]
    if operation == 'render-order-follows-incoming':
        return [k for k,t in incoming]
    if operation == 'changed-type-state-reset':
        return {k:state.get(k) if (k,t) in old else None for k,t in incoming}
    if operation == 'cleanup-before-replacement-mount':
        return [(k,'cleanup') for k,t in old if k in dict(incoming) and (k,t) not in incoming]+[(k,'mount') for k,t in incoming if k in dict(old) and (k,t) not in old]
    if operation == 'removed-state-pruning':
        return {k:v for k,v in state.items() if k in dict(incoming)}
    if operation == 'insertion-position':
        return {k:i for i,(k,t) in enumerate(incoming)}
    if operation == 'retained-instance-moves':
        return [k for i,(k,t) in enumerate(incoming) if (k,t) in old and old.index((k,t))!=i]
    raise ValueError('unknown modeled operation')
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('type-and-key-reuse scenario 1', solve('type-and-key-reuse', ([('a','card'),('b','card')],[('b','card'),('a','card')],{'a':N,'b':2})), ['b','a'])
check('type-and-key-reuse scenario 2', solve('type-and-key-reuse', ([], [('a','card')],{})), [])
check('type-and-key-reuse scenario 3', solve('type-and-key-reuse', ([('a','card')],[('a','panel')],{'a':0})), [])
check('type-and-key-reuse scenario 4', solve('type-and-key-reuse', ([('a','card'),('b','panel')],[('b','panel')],{'a':1,'b':None})), ['b'])
check('type-and-key-reuse scenario 5', solve('type-and-key-reuse', ([('a','card')],[],{'a':N})), [])
check('type-and-key-reuse scenario 6', solve('type-and-key-reuse', ([('a','card')],[('a','card'),('b','card')],{'a':False})), ['a'])
check('new-instance-mounts scenario 1', solve('new-instance-mounts', ([('a','card'),('b','card')],[('b','card'),('a','card')],{'a':N,'b':2})), [])
check('new-instance-mounts scenario 2', solve('new-instance-mounts', ([], [('a','card')],{})), ['a'])
check('new-instance-mounts scenario 3', solve('new-instance-mounts', ([('a','card')],[('a','panel')],{'a':0})), ['a'])
check('new-instance-mounts scenario 4', solve('new-instance-mounts', ([('a','card'),('b','panel')],[('b','panel')],{'a':1,'b':None})), [])
check('new-instance-mounts scenario 5', solve('new-instance-mounts', ([('a','card')],[],{'a':N})), [])
check('new-instance-mounts scenario 6', solve('new-instance-mounts', ([('a','card')],[('a','card'),('b','card')],{'a':False})), ['b'])
check('old-instance-unmounts scenario 1', solve('old-instance-unmounts', ([('a','card'),('b','card')],[('b','card'),('a','card')],{'a':N,'b':2})), [])
check('old-instance-unmounts scenario 2', solve('old-instance-unmounts', ([], [('a','card')],{})), [])
check('old-instance-unmounts scenario 3', solve('old-instance-unmounts', ([('a','card')],[('a','panel')],{'a':0})), ['a'])
check('old-instance-unmounts scenario 4', solve('old-instance-unmounts', ([('a','card'),('b','panel')],[('b','panel')],{'a':1,'b':None})), ['a'])
check('old-instance-unmounts scenario 5', solve('old-instance-unmounts', ([('a','card')],[],{'a':N})), ['a'])
check('old-instance-unmounts scenario 6', solve('old-instance-unmounts', ([('a','card')],[('a','card'),('b','card')],{'a':False})), [])
check('state-follows-key-through-reorder scenario 1', solve('state-follows-key-through-reorder', ([('a','card'),('b','card')],[('b','card'),('a','card')],{'a':N,'b':2})), [2,N])
check('state-follows-key-through-reorder scenario 2', solve('state-follows-key-through-reorder', ([], [('a','card')],{})), [])
check('state-follows-key-through-reorder scenario 3', solve('state-follows-key-through-reorder', ([('a','card')],[('a','panel')],{'a':0})), [])
check('state-follows-key-through-reorder scenario 4', solve('state-follows-key-through-reorder', ([('a','card'),('b','panel')],[('b','panel')],{'a':1,'b':None})), [None])
check('state-follows-key-through-reorder scenario 5', solve('state-follows-key-through-reorder', ([('a','card')],[],{'a':N})), [])
check('state-follows-key-through-reorder scenario 6', solve('state-follows-key-through-reorder', ([('a','card')],[('a','card'),('b','card')],{'a':False})), [False])
check('render-order-follows-incoming scenario 1', solve('render-order-follows-incoming', ([('a','card'),('b','card')],[('b','card'),('a','card')],{'a':N,'b':2})), ['b','a'])
check('render-order-follows-incoming scenario 2', solve('render-order-follows-incoming', ([], [('a','card')],{})), ['a'])
check('render-order-follows-incoming scenario 3', solve('render-order-follows-incoming', ([('a','card')],[('a','panel')],{'a':0})), ['a'])
check('render-order-follows-incoming scenario 4', solve('render-order-follows-incoming', ([('a','card'),('b','panel')],[('b','panel')],{'a':1,'b':None})), ['b'])
check('render-order-follows-incoming scenario 5', solve('render-order-follows-incoming', ([('a','card')],[],{'a':N})), [])
check('render-order-follows-incoming scenario 6', solve('render-order-follows-incoming', ([('a','card')],[('a','card'),('b','card')],{'a':False})), ['a','b'])
check('changed-type-state-reset scenario 1', solve('changed-type-state-reset', ([('a','card'),('b','card')],[('b','card'),('a','card')],{'a':N,'b':2})), {'b':2,'a':N})
check('changed-type-state-reset scenario 2', solve('changed-type-state-reset', ([], [('a','card')],{})), {'a':None})
check('changed-type-state-reset scenario 3', solve('changed-type-state-reset', ([('a','card')],[('a','panel')],{'a':0})), {'a':None})
check('changed-type-state-reset scenario 4', solve('changed-type-state-reset', ([('a','card'),('b','panel')],[('b','panel')],{'a':1,'b':None})), {'b':None})
check('changed-type-state-reset scenario 5', solve('changed-type-state-reset', ([('a','card')],[],{'a':N})), {})
check('changed-type-state-reset scenario 6', solve('changed-type-state-reset', ([('a','card')],[('a','card'),('b','card')],{'a':False})), {'a':False,'b':None})
check('cleanup-before-replacement-mount scenario 1', solve('cleanup-before-replacement-mount', ([('a','card'),('b','card')],[('b','card'),('a','card')],{'a':N,'b':2})), [])
check('cleanup-before-replacement-mount scenario 2', solve('cleanup-before-replacement-mount', ([], [('a','card')],{})), [])
check('cleanup-before-replacement-mount scenario 3', solve('cleanup-before-replacement-mount', ([('a','card')],[('a','panel')],{'a':0})), [('a','cleanup'),('a','mount')])
check('cleanup-before-replacement-mount scenario 4', solve('cleanup-before-replacement-mount', ([('a','card'),('b','panel')],[('b','panel')],{'a':1,'b':None})), [])
check('cleanup-before-replacement-mount scenario 5', solve('cleanup-before-replacement-mount', ([('a','card')],[],{'a':N})), [])
check('cleanup-before-replacement-mount scenario 6', solve('cleanup-before-replacement-mount', ([('a','card')],[('a','card'),('b','card')],{'a':False})), [])
check('removed-state-pruning scenario 1', solve('removed-state-pruning', ([('a','card'),('b','card')],[('b','card'),('a','card')],{'a':N,'b':2})), {'a':N,'b':2})
check('removed-state-pruning scenario 2', solve('removed-state-pruning', ([], [('a','card')],{})), {})
check('removed-state-pruning scenario 3', solve('removed-state-pruning', ([('a','card')],[('a','panel')],{'a':0})), {'a':0})
check('removed-state-pruning scenario 4', solve('removed-state-pruning', ([('a','card'),('b','panel')],[('b','panel')],{'a':1,'b':None})), {'b':None})
check('removed-state-pruning scenario 5', solve('removed-state-pruning', ([('a','card')],[],{'a':N})), {})
check('removed-state-pruning scenario 6', solve('removed-state-pruning', ([('a','card')],[('a','card'),('b','card')],{'a':False})), {'a':False})
check('insertion-position scenario 1', solve('insertion-position', ([('a','card'),('b','card')],[('b','card'),('a','card')],{'a':N,'b':2})), {'b':0,'a':1})
check('insertion-position scenario 2', solve('insertion-position', ([], [('a','card')],{})), {'a':0})
check('insertion-position scenario 3', solve('insertion-position', ([('a','card')],[('a','panel')],{'a':0})), {'a':0})
check('insertion-position scenario 4', solve('insertion-position', ([('a','card'),('b','panel')],[('b','panel')],{'a':1,'b':None})), {'b':0})
check('insertion-position scenario 5', solve('insertion-position', ([('a','card')],[],{'a':N})), {})
check('insertion-position scenario 6', solve('insertion-position', ([('a','card')],[('a','card'),('b','card')],{'a':False})), {'a':0,'b':1})
check('retained-instance-moves scenario 1', solve('retained-instance-moves', ([('a','card'),('b','card')],[('b','card'),('a','card')],{'a':N,'b':2})), ['b','a'])
check('retained-instance-moves scenario 2', solve('retained-instance-moves', ([], [('a','card')],{})), [])
check('retained-instance-moves scenario 3', solve('retained-instance-moves', ([('a','card')],[('a','panel')],{'a':0})), [])
check('retained-instance-moves scenario 4', solve('retained-instance-moves', ([('a','card'),('b','panel')],[('b','panel')],{'a':1,'b':None})), ['b'])
check('retained-instance-moves scenario 5', solve('retained-instance-moves', ([('a','card')],[],{'a':N})), [])
check('retained-instance-moves scenario 6', solve('retained-instance-moves', ([('a','card')],[('a','card'),('b','card')],{'a':False})), [])
check('reordering distinct state values for every seed: type-and-key-reuse', solve('type-and-key-reuse', ([('a','card'),('b','card')],[('b','card'),('a','card')],{'a':N+10,'b':2})), ['b','a'])
check('reordering distinct state values for every seed: new-instance-mounts', solve('new-instance-mounts', ([('a','card'),('b','card')],[('b','card'),('a','card')],{'a':N+10,'b':2})), [])
check('reordering distinct state values for every seed: old-instance-unmounts', solve('old-instance-unmounts', ([('a','card'),('b','card')],[('b','card'),('a','card')],{'a':N+10,'b':2})), [])
check('reordering distinct state values for every seed: state-follows-key-through-reorder', solve('state-follows-key-through-reorder', ([('a','card'),('b','card')],[('b','card'),('a','card')],{'a':N+10,'b':2})), [2,N+10])
check('reordering distinct state values for every seed: render-order-follows-incoming', solve('render-order-follows-incoming', ([('a','card'),('b','card')],[('b','card'),('a','card')],{'a':N+10,'b':2})), ['b','a'])
check('reordering distinct state values for every seed: changed-type-state-reset', solve('changed-type-state-reset', ([('a','card'),('b','card')],[('b','card'),('a','card')],{'a':N+10,'b':2})), {'b':2,'a':N+10})
check('reordering distinct state values for every seed: cleanup-before-replacement-mount', solve('cleanup-before-replacement-mount', ([('a','card'),('b','card')],[('b','card'),('a','card')],{'a':N+10,'b':2})), [])
check('reordering distinct state values for every seed: removed-state-pruning', solve('removed-state-pruning', ([('a','card'),('b','card')],[('b','card'),('a','card')],{'a':N+10,'b':2})), {'a':N+10,'b':2})
check('reordering distinct state values for every seed: insertion-position', solve('insertion-position', ([('a','card'),('b','card')],[('b','card'),('a','card')],{'a':N+10,'b':2})), {'b':0,'a':1})
check('reordering distinct state values for every seed: retained-instance-moves', solve('retained-instance-moves', ([('a','card'),('b','card')],[('b','card'),('a','card')],{'a':N+10,'b':2})), ['b','a'])
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 fixtureActualExpectedOutcome
type-and-key-reuse scenario 1['b', 'a']['b', 'a']Passed
type-and-key-reuse scenario 2[][]Passed
type-and-key-reuse scenario 3[][]Passed
type-and-key-reuse scenario 4['b']['b']Passed
type-and-key-reuse scenario 5[][]Passed
type-and-key-reuse scenario 6['a']['a']Passed
new-instance-mounts scenario 1['b', 'a'][]Failed
new-instance-mounts scenario 2['a']['a']Passed
new-instance-mounts scenario 3['a']['a']Passed
new-instance-mounts scenario 4['b'][]Failed
new-instance-mounts scenario 5[][]Passed
new-instance-mounts scenario 6['a', 'b']['b']Failed
old-instance-unmounts scenario 1[][]Passed
old-instance-unmounts scenario 2[][]Passed
old-instance-unmounts scenario 3['a']['a']Passed
old-instance-unmounts scenario 4['a']['a']Passed
old-instance-unmounts scenario 5['a']['a']Passed
old-instance-unmounts scenario 6[][]Passed
state-follows-key-through-reorder scenario 1[2, 1][2, 1]Passed
state-follows-key-through-reorder scenario 2[][]Passed
state-follows-key-through-reorder scenario 3[][]Passed
state-follows-key-through-reorder scenario 4[None][None]Passed
state-follows-key-through-reorder scenario 5[][]Passed
state-follows-key-through-reorder scenario 6[False][False]Passed
render-order-follows-incoming scenario 1['b', 'a']['b', 'a']Passed
render-order-follows-incoming scenario 2['a']['a']Passed
render-order-follows-incoming scenario 3['a']['a']Passed
render-order-follows-incoming scenario 4['b']['b']Passed
render-order-follows-incoming scenario 5[][]Passed
render-order-follows-incoming scenario 6['a', 'b']['a', 'b']Passed
changed-type-state-reset scenario 1{'a': 1, 'b': 2}{'a': 1, 'b': 2}Passed
changed-type-state-reset scenario 2{'a': None}{'a': None}Passed
changed-type-state-reset scenario 3{'a': None}{'a': None}Passed
changed-type-state-reset scenario 4{'b': None}{'b': None}Passed
changed-type-state-reset scenario 5{}{}Passed
changed-type-state-reset scenario 6{'a': False, 'b': None}{'a': False, 'b': None}Passed
cleanup-before-replacement-mount scenario 1[][]Passed
cleanup-before-replacement-mount scenario 2[][]Passed
cleanup-before-replacement-mount scenario 3[['a', 'cleanup'], ['a', 'mount']][['a', 'cleanup'], ['a', 'mount']]Passed
cleanup-before-replacement-mount scenario 4[][]Passed
cleanup-before-replacement-mount scenario 5[][]Passed
cleanup-before-replacement-mount scenario 6[][]Passed
removed-state-pruning scenario 1{'a': 1, 'b': 2}{'a': 1, 'b': 2}Passed
removed-state-pruning scenario 2{}{}Passed
removed-state-pruning scenario 3{'a': 0}{'a': 0}Passed
removed-state-pruning scenario 4{'b': None}{'b': None}Passed
removed-state-pruning scenario 5{}{}Passed
removed-state-pruning scenario 6{'a': False}{'a': False}Passed
insertion-position scenario 1{'a': 1, 'b': 0}{'a': 1, 'b': 0}Passed
insertion-position scenario 2{'a': 0}{'a': 0}Passed
insertion-position scenario 3{'a': 0}{'a': 0}Passed
insertion-position scenario 4{'b': 0}{'b': 0}Passed
insertion-position scenario 5{}{}Passed
insertion-position scenario 6{'a': 0, 'b': 1}{'a': 0, 'b': 1}Passed
retained-instance-moves scenario 1['b', 'a']['b', 'a']Passed
retained-instance-moves scenario 2[][]Passed
retained-instance-moves scenario 3[][]Passed
retained-instance-moves scenario 4['b']['b']Passed
retained-instance-moves scenario 5[][]Passed
retained-instance-moves scenario 6[][]Passed
reordering distinct state values for every seed: type-and-key-reuse['b', 'a']['b', 'a']Passed
reordering distinct state values for every seed: new-instance-mounts['b', 'a'][]Failed
reordering distinct state values for every seed: old-instance-unmounts[][]Passed
reordering distinct state values for every seed: state-follows-key-through-reorder[2, 11][2, 11]Passed
reordering distinct state values for every seed: render-order-follows-incoming['b', 'a']['b', 'a']Passed
reordering distinct state values for every seed: changed-type-state-reset{'a': 11, 'b': 2}{'a': 11, 'b': 2}Passed
reordering distinct state values for every seed: cleanup-before-replacement-mount[][]Passed
reordering distinct state values for every seed: removed-state-pruning{'a': 11, 'b': 2}{'a': 11, 'b': 2}Passed
reordering distinct state values for every seed: insertion-position{'a': 1, 'b': 0}{'a': 1, 'b': 0}Passed
reordering distinct state values for every seed: retained-instance-moves['b', 'a']['b', 'a']Passed

SHA-256 / a29abf910588331ba30c73f30e29de69c9c9862880cc41da63d8348cc5f84b1b

HELD IN THE MEMBER ARCHIVE

The verified repair and its recorded checks are member-only.

This mechanism has 70 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.

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Verification & scope

Only the explicitly specified operations and finite deterministic records are modeled; no browser or framework conformance is claimed. 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 2026-09-29T14:40:57.868597+00:00.

Case digest / b5d579e82482c500e47420e9dab64fa4ada470ade54b9e6767f68824b6fd0bf2