FAILURE MAP
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FA-20871 / Assistive announcements / Open access

Acknowledgment does not retire the in-flight utterance · case 01

The announcement trace violates the stated speech-backpressure contract.

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

ROOT CAUSE

Fault site: del flying[e[1]] is implemented as pass

THE FAILURE

Fault site: del flying[e[1]] is implemented as pass

Unsuccessful approach: The attempted repair substitutes flying.clear() and still violates a regression oracle.

Case contract

Transport starts with two credits. Queue appends speech. Pump sends up to available credits, records inflight IDs and consumes credit. Acknowledge known inflight ID releases exactly one credit; unknown ACK does nothing. Window sets nonnegative capacity and credit to max(0,capacity-inflight). Disconnect moves inflight messages before queued ones in original send order and restores credits; cancel removes only queued matching IDs. Return sent text trace, inflight IDs, queue IDs and credit.

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):
    capacity=2; credit=2; q=[]; flying={}; sent=[]
    for e in events:
        if e[0]=='queue': q.append([e[1],e[2]])
        elif e[0]=='pump':
            while q and credit>0:
                ident,text=q.pop(0)
                flying[ident]=text
                sent.append(text)
                credit-=1
        elif e[0]=='ack' and e[1] in flying:
            pass
            credit=max(0,capacity-len(flying))
        elif e[0]=='window':
            capacity=max(0,e[1]); credit=max(0,capacity-len(flying))
        elif e[0]=='disconnect':
            q=[[k,v] for k,v in flying.items()]+q
            flying.clear(); credit=capacity
        elif e[0]=='cancel': q=[x for x in q if x[0]!=e[1]]
    return [sent,list(flying),[x[0] for x in q],credit]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = ["[['queue','a','alpha'*N],['queue','b','beta'],['queue','c','gamma'],['pump'],['ack','a']]", "[['queue','a','alpha'*N],['queue','b','beta'],['queue','c','gamma'],['pump'],['disconnect'],['pump']]", "[['window',0],['queue','a','x'*N],['pump']]", "[['window',N+2],['queue','a','alpha'],['pump'],['ack','a'],['ack','a']]", "[['queue','a','x'*N],['queue','b','y'],['cancel','b']]", "[['ack','missing'],['pump']]", "[['queue','a','x'*N],['queue','b','y'],['pump'],['window',1],['ack','a'],['pump']]"]
expected = {1: [[['alpha', 'beta'], ['b'], ['c'], 1], [['alpha', 'beta', 'alpha', 'beta'], ['a', 'b'], ['c'], 0], [[], [], ['a'], 0], [['alpha'], [], [], 3], [[], [], ['a'], 2], [[], [], [], 2], [['x', 'y'], ['b'], [], 0]], 2: [[['alphaalpha', 'beta'], ['b'], ['c'], 1], [['alphaalpha', 'beta', 'alphaalpha', 'beta'], ['a', 'b'], ['c'], 0], [[], [], ['a'], 0], [['alpha'], [], [], 4], [[], [], ['a'], 2], [[], [], [], 2], [['xx', 'y'], ['b'], [], 0]], 3: [[['alphaalphaalpha', 'beta'], ['b'], ['c'], 1], [['alphaalphaalpha', 'beta', 'alphaalphaalpha', 'beta'], ['a', 'b'], ['c'], 0], [[], [], ['a'], 0], [['alpha'], [], [], 5], [[], [], ['a'], 2], [[], [], [], 2], [['xxx', 'y'], ['b'], [], 0]], 4: [[['alphaalphaalphaalpha', 'beta'], ['b'], ['c'], 1], [['alphaalphaalphaalpha', 'beta', 'alphaalphaalphaalpha', 'beta'], ['a', 'b'], ['c'], 0], [[], [], ['a'], 0], [['alpha'], [], [], 6], [[], [], ['a'], 2], [[], [], [], 2], [['xxxx', 'y'], ['b'], [], 0]], 5: [[['alphaalphaalphaalphaalpha', 'beta'], ['b'], ['c'], 1], [['alphaalphaalphaalphaalpha', 'beta', 'alphaalphaalphaalphaalpha', 'beta'], ['a', 'b'], ['c'], 0], [[], [], ['a'], 0], [['alpha'], [], [], 7], [[], [], ['a'], 2], [[], [], [], 2], [['xxxxx', 'y'], ['b'], [], 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 fixtureActualExpectedOutcome
trace-1[['alpha', 'beta'], ['a', 'b'], ['c'], 0][['alpha', 'beta'], ['b'], ['c'], 1]Failed
trace-2[['alpha', 'beta', 'alpha', 'beta'], ['a', 'b'], ['c'], 0][['alpha', 'beta', 'alpha', 'beta'], ['a', 'b'], ['c'], 0]Passed
trace-3[[], [], ['a'], 0][[], [], ['a'], 0]Passed
trace-4[['alpha'], ['a'], [], 2][['alpha'], [], [], 3]Failed
trace-5[[], [], ['a'], 2][[], [], ['a'], 2]Passed
trace-6[[], [], [], 2][[], [], [], 2]Passed
trace-7[['x', 'y'], ['a', 'b'], [], 0][['x', 'y'], ['b'], [], 0]Failed

SHA-256 / e73f419a778f7b73c4aa61f05a1d6f5dc13fb40bd062956b255d4dc6dfff2c0e

2 / The unsuccessful fix

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

N = 1
observations = []
def solve(events):
    capacity=2; credit=2; q=[]; flying={}; sent=[]
    for e in events:
        if e[0]=='queue': q.append([e[1],e[2]])
        elif e[0]=='pump':
            while q and credit>0:
                ident,text=q.pop(0)
                flying[ident]=text
                sent.append(text)
                credit-=1
        elif e[0]=='ack' and e[1] in flying:
            flying.clear()
            credit=max(0,capacity-len(flying))
        elif e[0]=='window':
            capacity=max(0,e[1]); credit=max(0,capacity-len(flying))
        elif e[0]=='disconnect':
            q=[[k,v] for k,v in flying.items()]+q
            flying.clear(); credit=capacity
        elif e[0]=='cancel': q=[x for x in q if x[0]!=e[1]]
    return [sent,list(flying),[x[0] for x in q],credit]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = ["[['queue','a','alpha'*N],['queue','b','beta'],['queue','c','gamma'],['pump'],['ack','a']]", "[['queue','a','alpha'*N],['queue','b','beta'],['queue','c','gamma'],['pump'],['disconnect'],['pump']]", "[['window',0],['queue','a','x'*N],['pump']]", "[['window',N+2],['queue','a','alpha'],['pump'],['ack','a'],['ack','a']]", "[['queue','a','x'*N],['queue','b','y'],['cancel','b']]", "[['ack','missing'],['pump']]", "[['queue','a','x'*N],['queue','b','y'],['pump'],['window',1],['ack','a'],['pump']]"]
expected = {1: [[['alpha', 'beta'], ['b'], ['c'], 1], [['alpha', 'beta', 'alpha', 'beta'], ['a', 'b'], ['c'], 0], [[], [], ['a'], 0], [['alpha'], [], [], 3], [[], [], ['a'], 2], [[], [], [], 2], [['x', 'y'], ['b'], [], 0]], 2: [[['alphaalpha', 'beta'], ['b'], ['c'], 1], [['alphaalpha', 'beta', 'alphaalpha', 'beta'], ['a', 'b'], ['c'], 0], [[], [], ['a'], 0], [['alpha'], [], [], 4], [[], [], ['a'], 2], [[], [], [], 2], [['xx', 'y'], ['b'], [], 0]], 3: [[['alphaalphaalpha', 'beta'], ['b'], ['c'], 1], [['alphaalphaalpha', 'beta', 'alphaalphaalpha', 'beta'], ['a', 'b'], ['c'], 0], [[], [], ['a'], 0], [['alpha'], [], [], 5], [[], [], ['a'], 2], [[], [], [], 2], [['xxx', 'y'], ['b'], [], 0]], 4: [[['alphaalphaalphaalpha', 'beta'], ['b'], ['c'], 1], [['alphaalphaalphaalpha', 'beta', 'alphaalphaalphaalpha', 'beta'], ['a', 'b'], ['c'], 0], [[], [], ['a'], 0], [['alpha'], [], [], 6], [[], [], ['a'], 2], [[], [], [], 2], [['xxxx', 'y'], ['b'], [], 0]], 5: [[['alphaalphaalphaalphaalpha', 'beta'], ['b'], ['c'], 1], [['alphaalphaalphaalphaalpha', 'beta', 'alphaalphaalphaalphaalpha', 'beta'], ['a', 'b'], ['c'], 0], [[], [], ['a'], 0], [['alpha'], [], [], 7], [[], [], ['a'], 2], [[], [], [], 2], [['xxxxx', 'y'], ['b'], [], 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 fixtureActualExpectedOutcome
trace-1[['alpha', 'beta'], [], ['c'], 2][['alpha', 'beta'], ['b'], ['c'], 1]Failed
trace-2[['alpha', 'beta', 'alpha', 'beta'], ['a', 'b'], ['c'], 0][['alpha', 'beta', 'alpha', 'beta'], ['a', 'b'], ['c'], 0]Passed
trace-3[[], [], ['a'], 0][[], [], ['a'], 0]Passed
trace-4[['alpha'], [], [], 3][['alpha'], [], [], 3]Passed
trace-5[[], [], ['a'], 2][[], [], ['a'], 2]Passed
trace-6[[], [], [], 2][[], [], [], 2]Passed
trace-7[['x', 'y'], [], [], 1][['x', 'y'], ['b'], [], 0]Failed

SHA-256 / c36b42be98702cd96cb48de55c57c6bb47c41bbe73d6f89fae3fc0ff479e02b8

HELD IN THE MEMBER ARCHIVE

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

This mechanism has 7 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

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 2026-09-29T14:40:23.293643+00:00.

Case digest / 7a6f72c2c205b5a563bb8809a5aa67c66cc7ecd810e8ce1e3c06e06477901fdd