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FA-8736 / Assistive semantics / Open access

Progress indicator representation: Out-of-range progress exposes invalid accessible values · case 01

Out-of-range progress exposes invalid accessible values.

Verified by executionVariant 1 · 7 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

The clamp operation uses `value` where the contract requires `max(minimum, min(value, maximum))`.

THE FAILURE

The clamp operation uses `value` where the contract requires `max(minimum, min(value, maximum))`.

Unsuccessful approach: Upper clamping alone still admits values below the minimum.

Case contract

Indeterminate indicators omit numeric value and are busy; determinate values clamp, percentages normalize the range, zero-span means complete, and busy reflects explicit state.

Why this case matters

A deterministic model of progress indicator representation; this isolates one interface invariant without requiring a browser.

1 / The failure

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

N = 1
observations = []
def solve(value, minimum, maximum, label, busy):
    if value is None: return {'role':'progressbar', 'label':label, 'busy':True}
    value = value
    ratio = (value-minimum)/(maximum-minimum) if maximum > minimum else 1
    return {'role':'progressbar', 'label':label, 'busy':busy, 'value':value, 'percent':round(ratio*100)}
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('indeterminate', solve(None, 0, 100, 'Upload', True), {'role': 'progressbar', 'label': 'Upload', 'busy': True})
check('below', solve(-5, 10, 30, 'Upload', True), {'role': 'progressbar', 'label': 'Upload', 'busy': True, 'value': 10, 'percent': 0})
check('above', solve(40, 10, 30, 'Upload', False), {'role': 'progressbar', 'label': 'Upload', 'busy': False, 'value': 30, 'percent': 100})
check('offset', solve(20, 10, 30, 'Upload', True), {'role': 'progressbar', 'label': 'Upload', 'busy': True, 'value': 20, 'percent': 50})
check('empty range', solve(10, 10, 10, 'Upload', False), {'role': 'progressbar', 'label': 'Upload', 'busy': False, 'value': 10, 'percent': 100})
check('parameterized progress range', solve(2*N,N,3*N,'Task',True), dict(role='progressbar',label='Task',busy=True,value=2*N,percent=50))
for repetition in range(N):
    check('repeat empty range', solve(10, 10, 10, 'Upload', False), {'role': 'progressbar', 'label': 'Upload', 'busy': False, 'value': 10, 'percent': 100})
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
indeterminate{'busy': True, 'label': 'Upload', 'role': 'progressbar'}{'busy': True, 'label': 'Upload', 'role': 'progressbar'}Passed
below{'busy': True, 'label': 'Upload', 'percent': -75, 'role': 'progressbar', 'value': -5}{'busy': True, 'label': 'Upload', 'percent': 0, 'role': 'progressbar', 'value': 10}Failed
above{'busy': False, 'label': 'Upload', 'percent': 150, 'role': 'progressbar', 'value': 40}{'busy': False, 'label': 'Upload', 'percent': 100, 'role': 'progressbar', 'value': 30}Failed
offset{'busy': True, 'label': 'Upload', 'percent': 50, 'role': 'progressbar', 'value': 20}{'busy': True, 'label': 'Upload', 'percent': 50, 'role': 'progressbar', 'value': 20}Passed
empty range{'busy': False, 'label': 'Upload', 'percent': 100, 'role': 'progressbar', 'value': 10}{'busy': False, 'label': 'Upload', 'percent': 100, 'role': 'progressbar', 'value': 10}Passed
parameterized progress range{'busy': True, 'label': 'Task', 'percent': 50, 'role': 'progressbar', 'value': 2}{'busy': True, 'label': 'Task', 'percent': 50, 'role': 'progressbar', 'value': 2}Passed
repeat empty range{'busy': False, 'label': 'Upload', 'percent': 100, 'role': 'progressbar', 'value': 10}{'busy': False, 'label': 'Upload', 'percent': 100, 'role': 'progressbar', 'value': 10}Passed

SHA-256 / 65e0fb430d115eead5e84e566657065bc3167612052af0a99f8d7da49ce0934e

2 / The unsuccessful fix

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

N = 1
observations = []
def solve(value, minimum, maximum, label, busy):
    if value is None: return {'role':'progressbar', 'label':label, 'busy':True}
    value = min(value, maximum)
    ratio = (value-minimum)/(maximum-minimum) if maximum > minimum else 1
    return {'role':'progressbar', 'label':label, 'busy':busy, 'value':value, 'percent':round(ratio*100)}
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('indeterminate', solve(None, 0, 100, 'Upload', True), {'role': 'progressbar', 'label': 'Upload', 'busy': True})
check('below', solve(-5, 10, 30, 'Upload', True), {'role': 'progressbar', 'label': 'Upload', 'busy': True, 'value': 10, 'percent': 0})
check('above', solve(40, 10, 30, 'Upload', False), {'role': 'progressbar', 'label': 'Upload', 'busy': False, 'value': 30, 'percent': 100})
check('offset', solve(20, 10, 30, 'Upload', True), {'role': 'progressbar', 'label': 'Upload', 'busy': True, 'value': 20, 'percent': 50})
check('empty range', solve(10, 10, 10, 'Upload', False), {'role': 'progressbar', 'label': 'Upload', 'busy': False, 'value': 10, 'percent': 100})
check('parameterized progress range', solve(2*N,N,3*N,'Task',True), dict(role='progressbar',label='Task',busy=True,value=2*N,percent=50))
for repetition in range(N):
    check('repeat empty range', solve(10, 10, 10, 'Upload', False), {'role': 'progressbar', 'label': 'Upload', 'busy': False, 'value': 10, 'percent': 100})
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
indeterminate{'busy': True, 'label': 'Upload', 'role': 'progressbar'}{'busy': True, 'label': 'Upload', 'role': 'progressbar'}Passed
below{'busy': True, 'label': 'Upload', 'percent': -75, 'role': 'progressbar', 'value': -5}{'busy': True, 'label': 'Upload', 'percent': 0, 'role': 'progressbar', 'value': 10}Failed
above{'busy': False, 'label': 'Upload', 'percent': 100, 'role': 'progressbar', 'value': 30}{'busy': False, 'label': 'Upload', 'percent': 100, 'role': 'progressbar', 'value': 30}Passed
offset{'busy': True, 'label': 'Upload', 'percent': 50, 'role': 'progressbar', 'value': 20}{'busy': True, 'label': 'Upload', 'percent': 50, 'role': 'progressbar', 'value': 20}Passed
empty range{'busy': False, 'label': 'Upload', 'percent': 100, 'role': 'progressbar', 'value': 10}{'busy': False, 'label': 'Upload', 'percent': 100, 'role': 'progressbar', 'value': 10}Passed
parameterized progress range{'busy': True, 'label': 'Task', 'percent': 50, 'role': 'progressbar', 'value': 2}{'busy': True, 'label': 'Task', 'percent': 50, 'role': 'progressbar', 'value': 2}Passed
repeat empty range{'busy': False, 'label': 'Upload', 'percent': 100, 'role': 'progressbar', 'value': 10}{'busy': False, 'label': 'Upload', 'percent': 100, 'role': 'progressbar', 'value': 10}Passed

SHA-256 / 6a396d1febe5731c2021e3607a7e61dac9eebcd0a135a69605e78b230911a798

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Verification & scope

This reproducer isolates one failure mechanism. Results cover the supplied fixtures. Variants within a family share a test contract and should remain grouped when constructing evaluation splits. Related mechanisms with a shared evaluation_group must also remain together; these controlled models are not independent production incidents.

Observations recorded using Python 3.12.14 at 2026-09-29T14:38:24.097999+00:00.

Case digest / 4fbbfb06c633bc8eae1915b95baeb138602cf4bdbe96abe40768b18547098468