FA-21026 / Assistive announcements / Open access

Unknown-total status announces an invented percentage · case 01

The announcement trace violates the stated progress-narration contract.

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

ROOT CAUSE

Fault site: out.append(t[0]+': '+str(t[2])+' items') is implemented as out.append(t[0]+': '+str(t[2])+'%')

VERIFIED REPAIR

Restore the stated transition: out.append(t[0]+': '+str(t[2])+' items')

Unsuccessful approach: The attempted repair substitutes out.append(t[0]+': '+str(e[2])+' items') and still violates a regression oracle.

Case contract

A task start records total and resets spoken milestone. Advance clamps monotone completion to total; a 25-percent bucket is announced only when it increases and before terminal status. Unknown total uses item-count messages. Complete announces exactly once, even for zero total. Fail announces failure and blocks progress. Retry reopens at zero and resets milestone. Rename affects future messages. Cancel drops task silently. Return speech and [id,done,status,bucket].

Why this case matters

Deterministic controlled model of assistive announcement delivery.

1 / The failure

Exit 1

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

N = 1
observations = []
def solve(events):
    tasks={}; out=[]
    for e in events:
        if e[0]=='start': tasks[e[1]]=[e[2],e[3],0,'running',0]
        elif e[0]=='cancel': tasks.pop(e[1],None)
        elif e[1] in tasks:
            t=tasks[e[1]]
            if e[0]=='rename': t[0]=e[2]
            elif e[0]=='retry': t[2]=0; t[3]='running'; t[4]=0
            elif e[0]=='fail' and t[3]=='running': t[3]='failed'; out.append(t[0]+': failed')
            elif e[0]=='complete' and t[3]=='running': t[3]='complete'; out.append(t[0]+': complete')
            elif e[0]=='advance' and t[3]=='running':
                t[2]=max(t[2],min(e[2],t[1]) if t[1]>=0 else e[2])
                if t[1]<0: out.append(t[0]+': '+str(t[2])+'%')
                elif t[1]>0:
                    bucket=t[2]*4//t[1]
                    if bucket>t[4]: out.append(t[0]+': '+str(bucket*25)+'%'); t[4]=bucket
    return [out,[[k,v[2],v[3],v[4]] for k,v in tasks.items()]]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = ["[['start','a','Download',4*N],['advance','a',N],['advance','a',N],['advance','a',0],['advance','a',8*N],['complete','a'],['complete','a']]", "[['start','a','Work',4*N],['advance','a',N],['fail','a'],['advance','a',4*N],['retry','a'],['advance','a',N],['rename','a','Retry'],['complete','a']]", "[['start','a','Unknown',-1],['advance','a',N+2],['advance','a',N],['complete','a']]", "[['start','a','Work',4*N],['advance','a',N],['fail','a'],['retry','a']]", "[['start','a','Zero',0],['complete','a'],['start','a','Again',N],['complete','a']]", "[['start','a','A',N],['start','b','B',N],['cancel','a']]", "[['start','a','Round',4*N+1],['advance','a',N]]", '[]']
expected = {1: [[['Download: 25%', 'Download: 100%', 'Download: complete'], [['a', 4, 'complete', 4]]], [['Work: 25%', 'Work: failed', 'Work: 25%', 'Retry: complete'], [['a', 1, 'complete', 1]]], [['Unknown: 3 items', 'Unknown: 3 items', 'Unknown: complete'], [['a', 3, 'complete', 0]]], [['Work: 25%', 'Work: failed'], [['a', 0, 'running', 0]]], [['Zero: complete', 'Again: complete'], [['a', 0, 'complete', 0]]], [[], [['b', 0, 'running', 0]]], [[], [['a', 1, 'running', 0]]], [[], []]], 2: [[['Download: 25%', 'Download: 100%', 'Download: complete'], [['a', 8, 'complete', 4]]], [['Work: 25%', 'Work: failed', 'Work: 25%', 'Retry: complete'], [['a', 2, 'complete', 1]]], [['Unknown: 4 items', 'Unknown: 4 items', 'Unknown: complete'], [['a', 4, 'complete', 0]]], [['Work: 25%', 'Work: failed'], [['a', 0, 'running', 0]]], [['Zero: complete', 'Again: complete'], [['a', 0, 'complete', 0]]], [[], [['b', 0, 'running', 0]]], [[], [['a', 2, 'running', 0]]], [[], []]], 3: [[['Download: 25%', 'Download: 100%', 'Download: complete'], [['a', 12, 'complete', 4]]], [['Work: 25%', 'Work: failed', 'Work: 25%', 'Retry: complete'], [['a', 3, 'complete', 1]]], [['Unknown: 5 items', 'Unknown: 5 items', 'Unknown: complete'], [['a', 5, 'complete', 0]]], [['Work: 25%', 'Work: failed'], [['a', 0, 'running', 0]]], [['Zero: complete', 'Again: complete'], [['a', 0, 'complete', 0]]], [[], [['b', 0, 'running', 0]]], [[], [['a', 3, 'running', 0]]], [[], []]], 4: [[['Download: 25%', 'Download: 100%', 'Download: complete'], [['a', 16, 'complete', 4]]], [['Work: 25%', 'Work: failed', 'Work: 25%', 'Retry: complete'], [['a', 4, 'complete', 1]]], [['Unknown: 6 items', 'Unknown: 6 items', 'Unknown: complete'], [['a', 6, 'complete', 0]]], [['Work: 25%', 'Work: failed'], [['a', 0, 'running', 0]]], [['Zero: complete', 'Again: complete'], [['a', 0, 'complete', 0]]], [[], [['b', 0, 'running', 0]]], [[], [['a', 4, 'running', 0]]], [[], []]], 5: [[['Download: 25%', 'Download: 100%', 'Download: complete'], [['a', 20, 'complete', 4]]], [['Work: 25%', 'Work: failed', 'Work: 25%', 'Retry: complete'], [['a', 5, 'complete', 1]]], [['Unknown: 7 items', 'Unknown: 7 items', 'Unknown: complete'], [['a', 7, 'complete', 0]]], [['Work: 25%', 'Work: failed'], [['a', 0, 'running', 0]]], [['Zero: complete', 'Again: complete'], [['a', 0, 'complete', 0]]], [[], [['b', 0, 'running', 0]]], [[], [['a', 5, 'running', 0]]], [[], []]]}[N]
for i, expression in enumerate(fixtures):
    check("trace-"+str(i+1), solve(eval(expression)), expected[i])
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
trace-1	`[['Download: 25%', 'Download: 100%', 'Download: complete'], [['a', 4, 'complete', 4]]]`	`[['Download: 25%', 'Download: 100%', 'Download: complete'], [['a', 4, 'complete', 4]]]`	Passed
trace-2	`[['Work: 25%', 'Work: failed', 'Work: 25%', 'Retry: complete'], [['a', 1, 'complete', 1]]]`	`[['Work: 25%', 'Work: failed', 'Work: 25%', 'Retry: complete'], [['a', 1, 'complete', 1]]]`	Passed
trace-3	`[['Unknown: 3%', 'Unknown: 3%', 'Unknown: complete'], [['a', 3, 'complete', 0]]]`	`[['Unknown: 3 items', 'Unknown: 3 items', 'Unknown: complete'], [['a', 3, 'complete', 0]]]`	Failed
trace-4	`[['Work: 25%', 'Work: failed'], [['a', 0, 'running', 0]]]`	`[['Work: 25%', 'Work: failed'], [['a', 0, 'running', 0]]]`	Passed
trace-5	`[['Zero: complete', 'Again: complete'], [['a', 0, 'complete', 0]]]`	`[['Zero: complete', 'Again: complete'], [['a', 0, 'complete', 0]]]`	Passed
trace-6	`[[], [['b', 0, 'running', 0]]]`	`[[], [['b', 0, 'running', 0]]]`	Passed
trace-7	`[[], [['a', 1, 'running', 0]]]`	`[[], [['a', 1, 'running', 0]]]`	Passed
trace-8	`[[], []]`	`[[], []]`	Passed

SHA-256 / 49a11d4e2cb6cf397780690ea1ce172ea2521cc49b697ee45121b5a3e10ad24b

2 / The unsuccessful fix

Exit 1

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

N = 1
observations = []
def solve(events):
    tasks={}; out=[]
    for e in events:
        if e[0]=='start': tasks[e[1]]=[e[2],e[3],0,'running',0]
        elif e[0]=='cancel': tasks.pop(e[1],None)
        elif e[1] in tasks:
            t=tasks[e[1]]
            if e[0]=='rename': t[0]=e[2]
            elif e[0]=='retry': t[2]=0; t[3]='running'; t[4]=0
            elif e[0]=='fail' and t[3]=='running': t[3]='failed'; out.append(t[0]+': failed')
            elif e[0]=='complete' and t[3]=='running': t[3]='complete'; out.append(t[0]+': complete')
            elif e[0]=='advance' and t[3]=='running':
                t[2]=max(t[2],min(e[2],t[1]) if t[1]>=0 else e[2])
                if t[1]<0: out.append(t[0]+': '+str(e[2])+' items')
                elif t[1]>0:
                    bucket=t[2]*4//t[1]
                    if bucket>t[4]: out.append(t[0]+': '+str(bucket*25)+'%'); t[4]=bucket
    return [out,[[k,v[2],v[3],v[4]] for k,v in tasks.items()]]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = ["[['start','a','Download',4*N],['advance','a',N],['advance','a',N],['advance','a',0],['advance','a',8*N],['complete','a'],['complete','a']]", "[['start','a','Work',4*N],['advance','a',N],['fail','a'],['advance','a',4*N],['retry','a'],['advance','a',N],['rename','a','Retry'],['complete','a']]", "[['start','a','Unknown',-1],['advance','a',N+2],['advance','a',N],['complete','a']]", "[['start','a','Work',4*N],['advance','a',N],['fail','a'],['retry','a']]", "[['start','a','Zero',0],['complete','a'],['start','a','Again',N],['complete','a']]", "[['start','a','A',N],['start','b','B',N],['cancel','a']]", "[['start','a','Round',4*N+1],['advance','a',N]]", '[]']
expected = {1: [[['Download: 25%', 'Download: 100%', 'Download: complete'], [['a', 4, 'complete', 4]]], [['Work: 25%', 'Work: failed', 'Work: 25%', 'Retry: complete'], [['a', 1, 'complete', 1]]], [['Unknown: 3 items', 'Unknown: 3 items', 'Unknown: complete'], [['a', 3, 'complete', 0]]], [['Work: 25%', 'Work: failed'], [['a', 0, 'running', 0]]], [['Zero: complete', 'Again: complete'], [['a', 0, 'complete', 0]]], [[], [['b', 0, 'running', 0]]], [[], [['a', 1, 'running', 0]]], [[], []]], 2: [[['Download: 25%', 'Download: 100%', 'Download: complete'], [['a', 8, 'complete', 4]]], [['Work: 25%', 'Work: failed', 'Work: 25%', 'Retry: complete'], [['a', 2, 'complete', 1]]], [['Unknown: 4 items', 'Unknown: 4 items', 'Unknown: complete'], [['a', 4, 'complete', 0]]], [['Work: 25%', 'Work: failed'], [['a', 0, 'running', 0]]], [['Zero: complete', 'Again: complete'], [['a', 0, 'complete', 0]]], [[], [['b', 0, 'running', 0]]], [[], [['a', 2, 'running', 0]]], [[], []]], 3: [[['Download: 25%', 'Download: 100%', 'Download: complete'], [['a', 12, 'complete', 4]]], [['Work: 25%', 'Work: failed', 'Work: 25%', 'Retry: complete'], [['a', 3, 'complete', 1]]], [['Unknown: 5 items', 'Unknown: 5 items', 'Unknown: complete'], [['a', 5, 'complete', 0]]], [['Work: 25%', 'Work: failed'], [['a', 0, 'running', 0]]], [['Zero: complete', 'Again: complete'], [['a', 0, 'complete', 0]]], [[], [['b', 0, 'running', 0]]], [[], [['a', 3, 'running', 0]]], [[], []]], 4: [[['Download: 25%', 'Download: 100%', 'Download: complete'], [['a', 16, 'complete', 4]]], [['Work: 25%', 'Work: failed', 'Work: 25%', 'Retry: complete'], [['a', 4, 'complete', 1]]], [['Unknown: 6 items', 'Unknown: 6 items', 'Unknown: complete'], [['a', 6, 'complete', 0]]], [['Work: 25%', 'Work: failed'], [['a', 0, 'running', 0]]], [['Zero: complete', 'Again: complete'], [['a', 0, 'complete', 0]]], [[], [['b', 0, 'running', 0]]], [[], [['a', 4, 'running', 0]]], [[], []]], 5: [[['Download: 25%', 'Download: 100%', 'Download: complete'], [['a', 20, 'complete', 4]]], [['Work: 25%', 'Work: failed', 'Work: 25%', 'Retry: complete'], [['a', 5, 'complete', 1]]], [['Unknown: 7 items', 'Unknown: 7 items', 'Unknown: complete'], [['a', 7, 'complete', 0]]], [['Work: 25%', 'Work: failed'], [['a', 0, 'running', 0]]], [['Zero: complete', 'Again: complete'], [['a', 0, 'complete', 0]]], [[], [['b', 0, 'running', 0]]], [[], [['a', 5, 'running', 0]]], [[], []]]}[N]
for i, expression in enumerate(fixtures):
    check("trace-"+str(i+1), solve(eval(expression)), expected[i])
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
trace-1	`[['Download: 25%', 'Download: 100%', 'Download: complete'], [['a', 4, 'complete', 4]]]`	`[['Download: 25%', 'Download: 100%', 'Download: complete'], [['a', 4, 'complete', 4]]]`	Passed
trace-2	`[['Work: 25%', 'Work: failed', 'Work: 25%', 'Retry: complete'], [['a', 1, 'complete', 1]]]`	`[['Work: 25%', 'Work: failed', 'Work: 25%', 'Retry: complete'], [['a', 1, 'complete', 1]]]`	Passed
trace-3	`[['Unknown: 3 items', 'Unknown: 1 items', 'Unknown: complete'], [['a', 3, 'complete', 0]]]`	`[['Unknown: 3 items', 'Unknown: 3 items', 'Unknown: complete'], [['a', 3, 'complete', 0]]]`	Failed
trace-4	`[['Work: 25%', 'Work: failed'], [['a', 0, 'running', 0]]]`	`[['Work: 25%', 'Work: failed'], [['a', 0, 'running', 0]]]`	Passed
trace-5	`[['Zero: complete', 'Again: complete'], [['a', 0, 'complete', 0]]]`	`[['Zero: complete', 'Again: complete'], [['a', 0, 'complete', 0]]]`	Passed
trace-6	`[[], [['b', 0, 'running', 0]]]`	`[[], [['b', 0, 'running', 0]]]`	Passed
trace-7	`[[], [['a', 1, 'running', 0]]]`	`[[], [['a', 1, 'running', 0]]]`	Passed
trace-8	`[[], []]`	`[[], []]`	Passed

SHA-256 / 003bb2eeafc697985967b9633dcea64f4b750769276bee8b6b3184a36f096fed

3 / The verified repair

Exit 0

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

N = 1
observations = []
def solve(events):
    tasks={}; out=[]
    for e in events:
        if e[0]=='start': tasks[e[1]]=[e[2],e[3],0,'running',0]
        elif e[0]=='cancel': tasks.pop(e[1],None)
        elif e[1] in tasks:
            t=tasks[e[1]]
            if e[0]=='rename': t[0]=e[2]
            elif e[0]=='retry': t[2]=0; t[3]='running'; t[4]=0
            elif e[0]=='fail' and t[3]=='running': t[3]='failed'; out.append(t[0]+': failed')
            elif e[0]=='complete' and t[3]=='running': t[3]='complete'; out.append(t[0]+': complete')
            elif e[0]=='advance' and t[3]=='running':
                t[2]=max(t[2],min(e[2],t[1]) if t[1]>=0 else e[2])
                if t[1]<0: out.append(t[0]+': '+str(t[2])+' items')
                elif t[1]>0:
                    bucket=t[2]*4//t[1]
                    if bucket>t[4]: out.append(t[0]+': '+str(bucket*25)+'%'); t[4]=bucket
    return [out,[[k,v[2],v[3],v[4]] for k,v in tasks.items()]]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = ["[['start','a','Download',4*N],['advance','a',N],['advance','a',N],['advance','a',0],['advance','a',8*N],['complete','a'],['complete','a']]", "[['start','a','Work',4*N],['advance','a',N],['fail','a'],['advance','a',4*N],['retry','a'],['advance','a',N],['rename','a','Retry'],['complete','a']]", "[['start','a','Unknown',-1],['advance','a',N+2],['advance','a',N],['complete','a']]", "[['start','a','Work',4*N],['advance','a',N],['fail','a'],['retry','a']]", "[['start','a','Zero',0],['complete','a'],['start','a','Again',N],['complete','a']]", "[['start','a','A',N],['start','b','B',N],['cancel','a']]", "[['start','a','Round',4*N+1],['advance','a',N]]", '[]']
expected = {1: [[['Download: 25%', 'Download: 100%', 'Download: complete'], [['a', 4, 'complete', 4]]], [['Work: 25%', 'Work: failed', 'Work: 25%', 'Retry: complete'], [['a', 1, 'complete', 1]]], [['Unknown: 3 items', 'Unknown: 3 items', 'Unknown: complete'], [['a', 3, 'complete', 0]]], [['Work: 25%', 'Work: failed'], [['a', 0, 'running', 0]]], [['Zero: complete', 'Again: complete'], [['a', 0, 'complete', 0]]], [[], [['b', 0, 'running', 0]]], [[], [['a', 1, 'running', 0]]], [[], []]], 2: [[['Download: 25%', 'Download: 100%', 'Download: complete'], [['a', 8, 'complete', 4]]], [['Work: 25%', 'Work: failed', 'Work: 25%', 'Retry: complete'], [['a', 2, 'complete', 1]]], [['Unknown: 4 items', 'Unknown: 4 items', 'Unknown: complete'], [['a', 4, 'complete', 0]]], [['Work: 25%', 'Work: failed'], [['a', 0, 'running', 0]]], [['Zero: complete', 'Again: complete'], [['a', 0, 'complete', 0]]], [[], [['b', 0, 'running', 0]]], [[], [['a', 2, 'running', 0]]], [[], []]], 3: [[['Download: 25%', 'Download: 100%', 'Download: complete'], [['a', 12, 'complete', 4]]], [['Work: 25%', 'Work: failed', 'Work: 25%', 'Retry: complete'], [['a', 3, 'complete', 1]]], [['Unknown: 5 items', 'Unknown: 5 items', 'Unknown: complete'], [['a', 5, 'complete', 0]]], [['Work: 25%', 'Work: failed'], [['a', 0, 'running', 0]]], [['Zero: complete', 'Again: complete'], [['a', 0, 'complete', 0]]], [[], [['b', 0, 'running', 0]]], [[], [['a', 3, 'running', 0]]], [[], []]], 4: [[['Download: 25%', 'Download: 100%', 'Download: complete'], [['a', 16, 'complete', 4]]], [['Work: 25%', 'Work: failed', 'Work: 25%', 'Retry: complete'], [['a', 4, 'complete', 1]]], [['Unknown: 6 items', 'Unknown: 6 items', 'Unknown: complete'], [['a', 6, 'complete', 0]]], [['Work: 25%', 'Work: failed'], [['a', 0, 'running', 0]]], [['Zero: complete', 'Again: complete'], [['a', 0, 'complete', 0]]], [[], [['b', 0, 'running', 0]]], [[], [['a', 4, 'running', 0]]], [[], []]], 5: [[['Download: 25%', 'Download: 100%', 'Download: complete'], [['a', 20, 'complete', 4]]], [['Work: 25%', 'Work: failed', 'Work: 25%', 'Retry: complete'], [['a', 5, 'complete', 1]]], [['Unknown: 7 items', 'Unknown: 7 items', 'Unknown: complete'], [['a', 7, 'complete', 0]]], [['Work: 25%', 'Work: failed'], [['a', 0, 'running', 0]]], [['Zero: complete', 'Again: complete'], [['a', 0, 'complete', 0]]], [[], [['b', 0, 'running', 0]]], [[], [['a', 5, 'running', 0]]], [[], []]]}[N]
for i, expression in enumerate(fixtures):
    check("trace-"+str(i+1), solve(eval(expression)), expected[i])
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
trace-1	`[['Download: 25%', 'Download: 100%', 'Download: complete'], [['a', 4, 'complete', 4]]]`	`[['Download: 25%', 'Download: 100%', 'Download: complete'], [['a', 4, 'complete', 4]]]`	Passed
trace-2	`[['Work: 25%', 'Work: failed', 'Work: 25%', 'Retry: complete'], [['a', 1, 'complete', 1]]]`	`[['Work: 25%', 'Work: failed', 'Work: 25%', 'Retry: complete'], [['a', 1, 'complete', 1]]]`	Passed
trace-3	`[['Unknown: 3 items', 'Unknown: 3 items', 'Unknown: complete'], [['a', 3, 'complete', 0]]]`	`[['Unknown: 3 items', 'Unknown: 3 items', 'Unknown: complete'], [['a', 3, 'complete', 0]]]`	Passed
trace-4	`[['Work: 25%', 'Work: failed'], [['a', 0, 'running', 0]]]`	`[['Work: 25%', 'Work: failed'], [['a', 0, 'running', 0]]]`	Passed
trace-5	`[['Zero: complete', 'Again: complete'], [['a', 0, 'complete', 0]]]`	`[['Zero: complete', 'Again: complete'], [['a', 0, 'complete', 0]]]`	Passed
trace-6	`[[], [['b', 0, 'running', 0]]]`	`[[], [['b', 0, 'running', 0]]]`	Passed
trace-7	`[[], [['a', 1, 'running', 0]]]`	`[[], [['a', 1, 'running', 0]]]`	Passed
trace-8	`[[], []]`	`[[], []]`	Passed

SHA-256 / c55b571569059db6f4393d6a07583784fbf331fb0d653cdf2bc1fa81215398b3

Verification & scope

Stipulated bounded policy, not a browser, speech engine, platform API, or standards conformance claim. 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 2026-09-29T14:40:24.624037+00:00.

Case digest / 45e19519dbb2d2b924e8d4a77b1ac60c9d0b47e9d78d2f122d9549d891a8824c