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FA-34536 / Notification interfaces / Open access

Swipe-to-dismiss notification feedback: second-pointer-down from committing · case 01

The second-pointer-down event leaves a notification in dragging instead of committing.

Verified by executionVariant 1 · 37 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

A second pointer resets a submitted dismissal into drag state.

THE FAILURE

A second pointer resets a submitted dismissal into drag state.

Unsuccessful approach: Rolling back before the command result can conflict with acceptance.

Case contract

Swipe-to-dismiss notification feedback is a bounded visual-notification workflow with mutable policy state {'offset': 0, 'threshold': 40, 'pointer': 7, 'removed': False}. Its default transition relation is {('resting', 'drag-start'): 'dragging', ('dragging', 'below-threshold-release'): 'returning', ('dragging', 'above-threshold-release'): 'committing', ('returning', 'snapback-finished'): 'resting', ('committing', 'dismiss-accepted'): 'exit-animating', ('committing', 'dismiss-rejected'): 'returning', ('exit-animating', 'animation-finished'): 'dismissed', ('dragging', 'pointer-cancel'): 'returning', ('exit-animating', 'reduced-motion-enabled'): 'dismissed', ('committing', 'second-pointer-down'): 'committing'}; domain inputs can suppress or redirect transitions and update policy fields, as specified in solve. Different-generation events are inert. Batches apply in order. Optional observe returns the selected policy field alongside the phase.

Why this case matters

Visual notification lifecycle ordering can leave an inbox or toast showing the wrong actionable state even when transport succeeds.

1 / The failure

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

N = 1
observations = []
def solve(initial, events, generation, payload=None, observe=None):
    table = {('resting', 'drag-start'): 'dragging', ('dragging', 'below-threshold-release'): 'returning', ('dragging', 'above-threshold-release'): 'committing', ('returning', 'snapback-finished'): 'resting', ('committing', 'dismiss-accepted'): 'exit-animating', ('committing', 'dismiss-rejected'): 'returning', ('exit-animating', 'animation-finished'): 'dismissed', ('dragging', 'pointer-cancel'): 'returning', ('exit-animating', 'reduced-motion-enabled'): 'dismissed', ('committing', 'second-pointer-down'): 'dragging'}
    data = json.loads(json.dumps({'offset': 0, 'threshold': 40, 'pointer': 7, 'removed': False})) if payload is None else {**json.loads(json.dumps({'offset': 0, 'threshold': 40, 'pointer': 7, 'removed': False})), **json.loads(json.dumps(payload))}
    state = initial
    for delivery in events:
        event, event_generation = delivery[:2]
        arg = delivery[2] if len(delivery) > 2 else {}
        if event_generation == generation:
            previous = state
            if event in ('below-threshold-release','above-threshold-release','pointer-cancel') and arg.get('pointer',data['pointer']) != data['pointer']: event = 'unknown-event'
            if event in ('below-threshold-release','above-threshold-release') and 'offset' in arg:
                data['offset'] = arg['offset']
                event = 'above-threshold-release' if abs(data['offset']) >= data['threshold'] else 'below-threshold-release'
            state = table.get((state, event), state)
            if state == 'resting': data['offset'] = 0
            if state == 'dismissed': data['removed'] = True
    return {'phase': state, 'value': data[observe]} if observe else state
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('resting / drag-start', solve('resting', [('drag-start', N)], N), 'dragging')
check('dragging / below-threshold-release', solve('dragging', [('below-threshold-release', N)], N), 'returning')
check('dragging / above-threshold-release', solve('dragging', [('above-threshold-release', N)], N), 'committing')
check('returning / snapback-finished', solve('returning', [('snapback-finished', N)], N), 'resting')
check('committing / dismiss-accepted', solve('committing', [('dismiss-accepted', N)], N), 'exit-animating')
check('committing / dismiss-rejected', solve('committing', [('dismiss-rejected', N)], N), 'returning')
check('exit-animating / animation-finished', solve('exit-animating', [('animation-finished', N)], N), 'dismissed')
check('dragging / pointer-cancel', solve('dragging', [('pointer-cancel', N)], N), 'returning')
check('exit-animating / reduced-motion-enabled', solve('exit-animating', [('reduced-motion-enabled', N)], N), 'dismissed')
check('committing / second-pointer-down', solve('committing', [('second-pointer-down', N)], N), 'committing')
check('older notification incarnation', solve('resting', [('drag-start', N - 1)], N), 'resting')
check('future notification incarnation', solve('resting', [('drag-start', N + 1)], N), 'resting')
check('unknown event is inert', solve('resting', [('unknown-event', N)], N), 'resting')
check('empty delivery batch', solve('resting', [], N), 'resting')
check('N stale deliveries before current delivery', solve('resting', [('drag-start', N - 1)] * N + [('drag-start', N)], N), 'dragging')
check('trace drag-start then below-threshold-release', solve('resting', [('drag-start', N), ('below-threshold-release', N)], N), 'returning')
check('trace drag-start then above-threshold-release', solve('resting', [('drag-start', N), ('above-threshold-release', N)], N), 'committing')
check('trace drag-start then pointer-cancel', solve('resting', [('drag-start', N), ('pointer-cancel', N)], N), 'returning')
check('trace below-threshold-release then snapback-finished', solve('dragging', [('below-threshold-release', N), ('snapback-finished', N)], N), 'resting')
check('trace above-threshold-release then dismiss-accepted', solve('dragging', [('above-threshold-release', N), ('dismiss-accepted', N)], N), 'exit-animating')
check('trace above-threshold-release then dismiss-rejected', solve('dragging', [('above-threshold-release', N), ('dismiss-rejected', N)], N), 'returning')
check('trace above-threshold-release then second-pointer-down', solve('dragging', [('above-threshold-release', N), ('second-pointer-down', N)], N), 'committing')
check('trace snapback-finished then drag-start', solve('returning', [('snapback-finished', N), ('drag-start', N)], N), 'dragging')
check('trace dismiss-accepted then animation-finished', solve('committing', [('dismiss-accepted', N), ('animation-finished', N)], N), 'dismissed')
check('trace dismiss-accepted then reduced-motion-enabled', solve('committing', [('dismiss-accepted', N), ('reduced-motion-enabled', N)], N), 'dismissed')
check('trace dismiss-rejected then snapback-finished', solve('committing', [('dismiss-rejected', N), ('snapback-finished', N)], N), 'resting')
check('trace pointer-cancel then snapback-finished', solve('dragging', [('pointer-cancel', N), ('snapback-finished', N)], N), 'resting')
check('trace second-pointer-down then dismiss-accepted', solve('committing', [('second-pointer-down', N), ('dismiss-accepted', N)], N), 'exit-animating')
check('trace second-pointer-down then dismiss-rejected', solve('committing', [('second-pointer-down', N), ('dismiss-rejected', N)], N), 'returning')
check('trace second-pointer-down then second-pointer-down', solve('committing', [('second-pointer-down', N), ('second-pointer-down', N)], N), 'committing')
check('domain state regression 1: offset', solve('dragging', [('above-threshold-release', N, {'offset': 39})], N, {}, 'offset'), {'phase': 'returning', 'value': 39})
check('domain state regression 2: offset', solve('dragging', [('below-threshold-release', N, {'offset': -40})], N, {}, 'offset'), {'phase': 'committing', 'value': -40})
check('domain state regression 3: offset', solve('dragging', [('above-threshold-release', N, {'pointer': 6, 'offset': 90})], N, {}, 'offset'), {'phase': 'dragging', 'value': 0})
check('domain state regression 4: offset', solve('returning', [('snapback-finished', N, {})], N, {'offset': 25}, 'offset'), {'phase': 'resting', 'value': 0})
check('domain state regression 5: removed', solve('exit-animating', [('reduced-motion-enabled', N, {})], N, {}, 'removed'), {'phase': 'dismissed', 'value': True})
check('domain state regression 6: removed', solve('committing', [('dismiss-rejected', N, {})], N, {'offset': 50}, 'removed'), {'phase': 'returning', 'value': False})
check('domain state regression 7: offset', solve('resting', [('drag-start', N, {}), ('above-threshold-release', N, {'offset': 39}), ('snapback-finished', N, {})], N, {}, 'offset'), {'phase': 'resting', 'value': 0})
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
resting / drag-startdraggingdraggingPassed
dragging / below-threshold-releasereturningreturningPassed
dragging / above-threshold-releasecommittingcommittingPassed
returning / snapback-finishedrestingrestingPassed
committing / dismiss-acceptedexit-animatingexit-animatingPassed
committing / dismiss-rejectedreturningreturningPassed
exit-animating / animation-finisheddismisseddismissedPassed
dragging / pointer-cancelreturningreturningPassed
exit-animating / reduced-motion-enableddismisseddismissedPassed
committing / second-pointer-downdraggingcommittingFailed
older notification incarnationrestingrestingPassed
future notification incarnationrestingrestingPassed
unknown event is inertrestingrestingPassed
empty delivery batchrestingrestingPassed
N stale deliveries before current deliverydraggingdraggingPassed
trace drag-start then below-threshold-releasereturningreturningPassed
trace drag-start then above-threshold-releasecommittingcommittingPassed
trace drag-start then pointer-cancelreturningreturningPassed
trace below-threshold-release then snapback-finishedrestingrestingPassed
trace above-threshold-release then dismiss-acceptedexit-animatingexit-animatingPassed
trace above-threshold-release then dismiss-rejectedreturningreturningPassed
trace above-threshold-release then second-pointer-downdraggingcommittingFailed
trace snapback-finished then drag-startdraggingdraggingPassed
trace dismiss-accepted then animation-finisheddismisseddismissedPassed
trace dismiss-accepted then reduced-motion-enableddismisseddismissedPassed
trace dismiss-rejected then snapback-finishedrestingrestingPassed
trace pointer-cancel then snapback-finishedrestingrestingPassed
trace second-pointer-down then dismiss-accepteddraggingexit-animatingFailed
trace second-pointer-down then dismiss-rejecteddraggingreturningFailed
trace second-pointer-down then second-pointer-downdraggingcommittingFailed
domain state regression 1: offset{'phase': 'returning', 'value': 39}{'phase': 'returning', 'value': 39}Passed
domain state regression 2: offset{'phase': 'committing', 'value': -40}{'phase': 'committing', 'value': -40}Passed
domain state regression 3: offset{'phase': 'dragging', 'value': 0}{'phase': 'dragging', 'value': 0}Passed
domain state regression 4: offset{'phase': 'resting', 'value': 0}{'phase': 'resting', 'value': 0}Passed
domain state regression 5: removed{'phase': 'dismissed', 'value': True}{'phase': 'dismissed', 'value': True}Passed
domain state regression 6: removed{'phase': 'returning', 'value': False}{'phase': 'returning', 'value': False}Passed
domain state regression 7: offset{'phase': 'resting', 'value': 0}{'phase': 'resting', 'value': 0}Passed

SHA-256 / 1273f17df99bde38224afaa19a84776247f94a4b8b86fe0c7ceb4f9b66f1d8a6

2 / The unsuccessful fix

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

N = 1
observations = []
def solve(initial, events, generation, payload=None, observe=None):
    table = {('resting', 'drag-start'): 'dragging', ('dragging', 'below-threshold-release'): 'returning', ('dragging', 'above-threshold-release'): 'committing', ('returning', 'snapback-finished'): 'resting', ('committing', 'dismiss-accepted'): 'exit-animating', ('committing', 'dismiss-rejected'): 'returning', ('exit-animating', 'animation-finished'): 'dismissed', ('dragging', 'pointer-cancel'): 'returning', ('exit-animating', 'reduced-motion-enabled'): 'dismissed', ('committing', 'second-pointer-down'): 'returning'}
    data = json.loads(json.dumps({'offset': 0, 'threshold': 40, 'pointer': 7, 'removed': False})) if payload is None else {**json.loads(json.dumps({'offset': 0, 'threshold': 40, 'pointer': 7, 'removed': False})), **json.loads(json.dumps(payload))}
    state = initial
    for delivery in events:
        event, event_generation = delivery[:2]
        arg = delivery[2] if len(delivery) > 2 else {}
        if event_generation == generation:
            previous = state
            if event in ('below-threshold-release','above-threshold-release','pointer-cancel') and arg.get('pointer',data['pointer']) != data['pointer']: event = 'unknown-event'
            if event in ('below-threshold-release','above-threshold-release') and 'offset' in arg:
                data['offset'] = arg['offset']
                event = 'above-threshold-release' if abs(data['offset']) >= data['threshold'] else 'below-threshold-release'
            state = table.get((state, event), state)
            if state == 'resting': data['offset'] = 0
            if state == 'dismissed': data['removed'] = True
    return {'phase': state, 'value': data[observe]} if observe else state
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('resting / drag-start', solve('resting', [('drag-start', N)], N), 'dragging')
check('dragging / below-threshold-release', solve('dragging', [('below-threshold-release', N)], N), 'returning')
check('dragging / above-threshold-release', solve('dragging', [('above-threshold-release', N)], N), 'committing')
check('returning / snapback-finished', solve('returning', [('snapback-finished', N)], N), 'resting')
check('committing / dismiss-accepted', solve('committing', [('dismiss-accepted', N)], N), 'exit-animating')
check('committing / dismiss-rejected', solve('committing', [('dismiss-rejected', N)], N), 'returning')
check('exit-animating / animation-finished', solve('exit-animating', [('animation-finished', N)], N), 'dismissed')
check('dragging / pointer-cancel', solve('dragging', [('pointer-cancel', N)], N), 'returning')
check('exit-animating / reduced-motion-enabled', solve('exit-animating', [('reduced-motion-enabled', N)], N), 'dismissed')
check('committing / second-pointer-down', solve('committing', [('second-pointer-down', N)], N), 'committing')
check('older notification incarnation', solve('resting', [('drag-start', N - 1)], N), 'resting')
check('future notification incarnation', solve('resting', [('drag-start', N + 1)], N), 'resting')
check('unknown event is inert', solve('resting', [('unknown-event', N)], N), 'resting')
check('empty delivery batch', solve('resting', [], N), 'resting')
check('N stale deliveries before current delivery', solve('resting', [('drag-start', N - 1)] * N + [('drag-start', N)], N), 'dragging')
check('trace drag-start then below-threshold-release', solve('resting', [('drag-start', N), ('below-threshold-release', N)], N), 'returning')
check('trace drag-start then above-threshold-release', solve('resting', [('drag-start', N), ('above-threshold-release', N)], N), 'committing')
check('trace drag-start then pointer-cancel', solve('resting', [('drag-start', N), ('pointer-cancel', N)], N), 'returning')
check('trace below-threshold-release then snapback-finished', solve('dragging', [('below-threshold-release', N), ('snapback-finished', N)], N), 'resting')
check('trace above-threshold-release then dismiss-accepted', solve('dragging', [('above-threshold-release', N), ('dismiss-accepted', N)], N), 'exit-animating')
check('trace above-threshold-release then dismiss-rejected', solve('dragging', [('above-threshold-release', N), ('dismiss-rejected', N)], N), 'returning')
check('trace above-threshold-release then second-pointer-down', solve('dragging', [('above-threshold-release', N), ('second-pointer-down', N)], N), 'committing')
check('trace snapback-finished then drag-start', solve('returning', [('snapback-finished', N), ('drag-start', N)], N), 'dragging')
check('trace dismiss-accepted then animation-finished', solve('committing', [('dismiss-accepted', N), ('animation-finished', N)], N), 'dismissed')
check('trace dismiss-accepted then reduced-motion-enabled', solve('committing', [('dismiss-accepted', N), ('reduced-motion-enabled', N)], N), 'dismissed')
check('trace dismiss-rejected then snapback-finished', solve('committing', [('dismiss-rejected', N), ('snapback-finished', N)], N), 'resting')
check('trace pointer-cancel then snapback-finished', solve('dragging', [('pointer-cancel', N), ('snapback-finished', N)], N), 'resting')
check('trace second-pointer-down then dismiss-accepted', solve('committing', [('second-pointer-down', N), ('dismiss-accepted', N)], N), 'exit-animating')
check('trace second-pointer-down then dismiss-rejected', solve('committing', [('second-pointer-down', N), ('dismiss-rejected', N)], N), 'returning')
check('trace second-pointer-down then second-pointer-down', solve('committing', [('second-pointer-down', N), ('second-pointer-down', N)], N), 'committing')
check('domain state regression 1: offset', solve('dragging', [('above-threshold-release', N, {'offset': 39})], N, {}, 'offset'), {'phase': 'returning', 'value': 39})
check('domain state regression 2: offset', solve('dragging', [('below-threshold-release', N, {'offset': -40})], N, {}, 'offset'), {'phase': 'committing', 'value': -40})
check('domain state regression 3: offset', solve('dragging', [('above-threshold-release', N, {'pointer': 6, 'offset': 90})], N, {}, 'offset'), {'phase': 'dragging', 'value': 0})
check('domain state regression 4: offset', solve('returning', [('snapback-finished', N, {})], N, {'offset': 25}, 'offset'), {'phase': 'resting', 'value': 0})
check('domain state regression 5: removed', solve('exit-animating', [('reduced-motion-enabled', N, {})], N, {}, 'removed'), {'phase': 'dismissed', 'value': True})
check('domain state regression 6: removed', solve('committing', [('dismiss-rejected', N, {})], N, {'offset': 50}, 'removed'), {'phase': 'returning', 'value': False})
check('domain state regression 7: offset', solve('resting', [('drag-start', N, {}), ('above-threshold-release', N, {'offset': 39}), ('snapback-finished', N, {})], N, {}, 'offset'), {'phase': 'resting', 'value': 0})
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
resting / drag-startdraggingdraggingPassed
dragging / below-threshold-releasereturningreturningPassed
dragging / above-threshold-releasecommittingcommittingPassed
returning / snapback-finishedrestingrestingPassed
committing / dismiss-acceptedexit-animatingexit-animatingPassed
committing / dismiss-rejectedreturningreturningPassed
exit-animating / animation-finisheddismisseddismissedPassed
dragging / pointer-cancelreturningreturningPassed
exit-animating / reduced-motion-enableddismisseddismissedPassed
committing / second-pointer-downreturningcommittingFailed
older notification incarnationrestingrestingPassed
future notification incarnationrestingrestingPassed
unknown event is inertrestingrestingPassed
empty delivery batchrestingrestingPassed
N stale deliveries before current deliverydraggingdraggingPassed
trace drag-start then below-threshold-releasereturningreturningPassed
trace drag-start then above-threshold-releasecommittingcommittingPassed
trace drag-start then pointer-cancelreturningreturningPassed
trace below-threshold-release then snapback-finishedrestingrestingPassed
trace above-threshold-release then dismiss-acceptedexit-animatingexit-animatingPassed
trace above-threshold-release then dismiss-rejectedreturningreturningPassed
trace above-threshold-release then second-pointer-downreturningcommittingFailed
trace snapback-finished then drag-startdraggingdraggingPassed
trace dismiss-accepted then animation-finisheddismisseddismissedPassed
trace dismiss-accepted then reduced-motion-enableddismisseddismissedPassed
trace dismiss-rejected then snapback-finishedrestingrestingPassed
trace pointer-cancel then snapback-finishedrestingrestingPassed
trace second-pointer-down then dismiss-acceptedreturningexit-animatingFailed
trace second-pointer-down then dismiss-rejectedreturningreturningPassed
trace second-pointer-down then second-pointer-downreturningcommittingFailed
domain state regression 1: offset{'phase': 'returning', 'value': 39}{'phase': 'returning', 'value': 39}Passed
domain state regression 2: offset{'phase': 'committing', 'value': -40}{'phase': 'committing', 'value': -40}Passed
domain state regression 3: offset{'phase': 'dragging', 'value': 0}{'phase': 'dragging', 'value': 0}Passed
domain state regression 4: offset{'phase': 'resting', 'value': 0}{'phase': 'resting', 'value': 0}Passed
domain state regression 5: removed{'phase': 'dismissed', 'value': True}{'phase': 'dismissed', 'value': True}Passed
domain state regression 6: removed{'phase': 'returning', 'value': False}{'phase': 'returning', 'value': False}Passed
domain state regression 7: offset{'phase': 'resting', 'value': 0}{'phase': 'resting', 'value': 0}Passed

SHA-256 / 43af2cfaf7d30ea1fce0111f4471b72ac7abe7bec8d898286ea27f0e5a7d5a96

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This mechanism has 37 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.

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Verification & scope

Stipulated single-notification state and policy model only. Event delivery and acknowledgements are explicit test inputs. No DOM, accessibility announcements, live timers, networking, actual rendering, or production-platform conformance is simulated. 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 2026-09-29T14:42:32.841744+00:00.

Case digest / 98733057bc3d6d484f86e5fab157714b63ea954572a35a304b5cf62d1babbb2c