FA-21391 / Assistive announcements / Open access
Move to end lands before the last character · case 01
The announcement trace violates the stated edit-narration contract.
ROOT CAUSE
Fault site: if op=='move': cursor=max(0,min(len(text),e[1])) is implemented as if op=='move': cursor=max(0,min(max(0,len(text)-1),e[1]))
THE FAILURE
Fault site: if op=='move': cursor=max(0,min(len(text),e[1])) is implemented as if op=='move': cursor=max(0,min(max(0,len(text)-1),e[1]))
Unsuccessful approach: The attempted repair substitutes if op=='move': cursor=max(0,min(len(text),e[1]+1)) and still violates a regression oracle.
Case contract
Document announcement state stores text and a cursor. Insert inserts at clamped cursor and announces inserted span. Backspace removes up to count before cursor and announces removed span in original order. Delete removes after cursor without moving it. Move clamps cursor. Replace range uses sorted clamped endpoints, announces old/new, moves cursor to replacement end. Undo restores text and cursor from last mutating edit and announces restored text. Silent toggles suppress cues but not state or undo. Return cues,text,cursor.
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):
text=''; cursor=0; history=[]; silent=False; out=[]
for e in events:
op=e[0]
if op=='move': cursor=max(0,min(max(0,len(text)-1),e[1]))
elif op=='silent': silent=e[1]
elif op=='undo' and history:
text,cursor=history.pop()
if not silent: out.append(['undo',text])
elif op in ('insert','backspace','delete','replace'):
history.append([text,cursor])
if op=='insert':
text=text[:cursor]+e[1]+text[cursor:]; cursor+=len(e[1]); cue=['insert',e[1]]
elif op=='backspace':
start=max(0,cursor-e[1]); cue=['remove',text[start:cursor]]
text=text[:start]+text[cursor:]; cursor=start
elif op=='delete':
end=min(len(text),cursor+e[1]); cue=['remove',text[cursor:end]]
text=text[:cursor]+text[end:]
else:
a,b=sorted([max(0,min(len(text),e[1])),max(0,min(len(text),e[2]))])
cue=['replace',text[a:b],e[3]]; text=text[:a]+e[3]+text[b:]; cursor=a+len(e[3])
if not silent: out.append(cue)
return [out,text,cursor]
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = ["[['insert','abcd'*N],['move',2],['insert','XY'],['backspace',2],['undo'],['undo']]", "[['insert','abcdef'*N],['move',4],['backspace',2]]", "[['insert','abcdef'*N],['move',2],['delete',2]]", "[['insert','abcdef'*N],['replace',5,2,'Z']]", "[['insert','abcdef'*N],['replace',5,2,'Z'],['undo']]", "[['silent',True],['insert','secret'*N],['silent',False],['move',99],['insert','!']]", "[['insert','x'*N],['move',-5],['backspace',4],['delete',99],['undo']]", '[]']
expected = {1: [[[['insert', 'abcd'], ['insert', 'XY'], ['remove', 'XY'], ['undo', 'abXYcd'], ['undo', 'abcd']], 'abcd', 2], [[['insert', 'abcdef'], ['remove', 'cd']], 'abef', 2], [[['insert', 'abcdef'], ['remove', 'cd']], 'abef', 2], [[['insert', 'abcdef'], ['replace', 'cde', 'Z']], 'abZf', 3], [[['insert', 'abcdef'], ['replace', 'cde', 'Z'], ['undo', 'abcdef']], 'abcdef', 6], [[['insert', '!']], 'secret!', 7], [[['insert', 'x'], ['remove', ''], ['remove', 'x'], ['undo', 'x']], 'x', 0], [[], '', 0]], 2: [[[['insert', 'abcdabcd'], ['insert', 'XY'], ['remove', 'XY'], ['undo', 'abXYcdabcd'], ['undo', 'abcdabcd']], 'abcdabcd', 2], [[['insert', 'abcdefabcdef'], ['remove', 'cd']], 'abefabcdef', 2], [[['insert', 'abcdefabcdef'], ['remove', 'cd']], 'abefabcdef', 2], [[['insert', 'abcdefabcdef'], ['replace', 'cde', 'Z']], 'abZfabcdef', 3], [[['insert', 'abcdefabcdef'], ['replace', 'cde', 'Z'], ['undo', 'abcdefabcdef']], 'abcdefabcdef', 12], [[['insert', '!']], 'secretsecret!', 13], [[['insert', 'xx'], ['remove', ''], ['remove', 'xx'], ['undo', 'xx']], 'xx', 0], [[], '', 0]], 3: [[[['insert', 'abcdabcdabcd'], ['insert', 'XY'], ['remove', 'XY'], ['undo', 'abXYcdabcdabcd'], ['undo', 'abcdabcdabcd']], 'abcdabcdabcd', 2], [[['insert', 'abcdefabcdefabcdef'], ['remove', 'cd']], 'abefabcdefabcdef', 2], [[['insert', 'abcdefabcdefabcdef'], ['remove', 'cd']], 'abefabcdefabcdef', 2], [[['insert', 'abcdefabcdefabcdef'], ['replace', 'cde', 'Z']], 'abZfabcdefabcdef', 3], [[['insert', 'abcdefabcdefabcdef'], ['replace', 'cde', 'Z'], ['undo', 'abcdefabcdefabcdef']], 'abcdefabcdefabcdef', 18], [[['insert', '!']], 'secretsecretsecret!', 19], [[['insert', 'xxx'], ['remove', ''], ['remove', 'xxx'], ['undo', 'xxx']], 'xxx', 0], [[], '', 0]], 4: [[[['insert', 'abcdabcdabcdabcd'], ['insert', 'XY'], ['remove', 'XY'], ['undo', 'abXYcdabcdabcdabcd'], ['undo', 'abcdabcdabcdabcd']], 'abcdabcdabcdabcd', 2], [[['insert', 'abcdefabcdefabcdefabcdef'], ['remove', 'cd']], 'abefabcdefabcdefabcdef', 2], [[['insert', 'abcdefabcdefabcdefabcdef'], ['remove', 'cd']], 'abefabcdefabcdefabcdef', 2], [[['insert', 'abcdefabcdefabcdefabcdef'], ['replace', 'cde', 'Z']], 'abZfabcdefabcdefabcdef', 3], [[['insert', 'abcdefabcdefabcdefabcdef'], ['replace', 'cde', 'Z'], ['undo', 'abcdefabcdefabcdefabcdef']], 'abcdefabcdefabcdefabcdef', 24], [[['insert', '!']], 'secretsecretsecretsecret!', 25], [[['insert', 'xxxx'], ['remove', ''], ['remove', 'xxxx'], ['undo', 'xxxx']], 'xxxx', 0], [[], '', 0]], 5: [[[['insert', 'abcdabcdabcdabcdabcd'], ['insert', 'XY'], ['remove', 'XY'], ['undo', 'abXYcdabcdabcdabcdabcd'], ['undo', 'abcdabcdabcdabcdabcd']], 'abcdabcdabcdabcdabcd', 2], [[['insert', 'abcdefabcdefabcdefabcdefabcdef'], ['remove', 'cd']], 'abefabcdefabcdefabcdefabcdef', 2], [[['insert', 'abcdefabcdefabcdefabcdefabcdef'], ['remove', 'cd']], 'abefabcdefabcdefabcdefabcdef', 2], [[['insert', 'abcdefabcdefabcdefabcdefabcdef'], ['replace', 'cde', 'Z']], 'abZfabcdefabcdefabcdefabcdef', 3], [[['insert', 'abcdefabcdefabcdefabcdefabcdef'], ['replace', 'cde', 'Z'], ['undo', 'abcdefabcdefabcdefabcdefabcdef']], 'abcdefabcdefabcdefabcdefabcdef', 30], [[['insert', '!']], 'secretsecretsecretsecretsecret!', 31], [[['insert', 'xxxxx'], ['remove', ''], ['remove', 'xxxxx'], ['undo', 'xxxxx']], 'xxxxx', 0], [[], '', 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 | [[['insert', 'abcd'], ['insert', 'XY'], ['remove', 'XY'], ['undo', 'abXYcd'], ['undo', 'abcd']], 'abcd', 2] | [[['insert', 'abcd'], ['insert', 'XY'], ['remove', 'XY'], ['undo', 'abXYcd'], ['undo', 'abcd']], 'abcd', 2] | Passed |
| trace-2 | [[['insert', 'abcdef'], ['remove', 'cd']], 'abef', 2] | [[['insert', 'abcdef'], ['remove', 'cd']], 'abef', 2] | Passed |
| trace-3 | [[['insert', 'abcdef'], ['remove', 'cd']], 'abef', 2] | [[['insert', 'abcdef'], ['remove', 'cd']], 'abef', 2] | Passed |
| trace-4 | [[['insert', 'abcdef'], ['replace', 'cde', 'Z']], 'abZf', 3] | [[['insert', 'abcdef'], ['replace', 'cde', 'Z']], 'abZf', 3] | Passed |
| trace-5 | [[['insert', 'abcdef'], ['replace', 'cde', 'Z'], ['undo', 'abcdef']], 'abcdef', 6] | [[['insert', 'abcdef'], ['replace', 'cde', 'Z'], ['undo', 'abcdef']], 'abcdef', 6] | Passed |
| trace-6 | [[['insert', '!']], 'secre!t', 6] | [[['insert', '!']], 'secret!', 7] | Failed |
| trace-7 | [[['insert', 'x'], ['remove', ''], ['remove', 'x'], ['undo', 'x']], 'x', 0] | [[['insert', 'x'], ['remove', ''], ['remove', 'x'], ['undo', 'x']], 'x', 0] | Passed |
| trace-8 | [[], '', 0] | [[], '', 0] | Passed |
SHA-256 / 46e287bef9f96e64d2a11bac00621a54bab809776ceef3c2be6403542cf889f1
2 / The unsuccessful fix
Exit 1"""Failure Map reference implementation. Python standard library only."""
import json
N = 1
observations = []
def solve(events):
text=''; cursor=0; history=[]; silent=False; out=[]
for e in events:
op=e[0]
if op=='move': cursor=max(0,min(len(text),e[1]+1))
elif op=='silent': silent=e[1]
elif op=='undo' and history:
text,cursor=history.pop()
if not silent: out.append(['undo',text])
elif op in ('insert','backspace','delete','replace'):
history.append([text,cursor])
if op=='insert':
text=text[:cursor]+e[1]+text[cursor:]; cursor+=len(e[1]); cue=['insert',e[1]]
elif op=='backspace':
start=max(0,cursor-e[1]); cue=['remove',text[start:cursor]]
text=text[:start]+text[cursor:]; cursor=start
elif op=='delete':
end=min(len(text),cursor+e[1]); cue=['remove',text[cursor:end]]
text=text[:cursor]+text[end:]
else:
a,b=sorted([max(0,min(len(text),e[1])),max(0,min(len(text),e[2]))])
cue=['replace',text[a:b],e[3]]; text=text[:a]+e[3]+text[b:]; cursor=a+len(e[3])
if not silent: out.append(cue)
return [out,text,cursor]
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = ["[['insert','abcd'*N],['move',2],['insert','XY'],['backspace',2],['undo'],['undo']]", "[['insert','abcdef'*N],['move',4],['backspace',2]]", "[['insert','abcdef'*N],['move',2],['delete',2]]", "[['insert','abcdef'*N],['replace',5,2,'Z']]", "[['insert','abcdef'*N],['replace',5,2,'Z'],['undo']]", "[['silent',True],['insert','secret'*N],['silent',False],['move',99],['insert','!']]", "[['insert','x'*N],['move',-5],['backspace',4],['delete',99],['undo']]", '[]']
expected = {1: [[[['insert', 'abcd'], ['insert', 'XY'], ['remove', 'XY'], ['undo', 'abXYcd'], ['undo', 'abcd']], 'abcd', 2], [[['insert', 'abcdef'], ['remove', 'cd']], 'abef', 2], [[['insert', 'abcdef'], ['remove', 'cd']], 'abef', 2], [[['insert', 'abcdef'], ['replace', 'cde', 'Z']], 'abZf', 3], [[['insert', 'abcdef'], ['replace', 'cde', 'Z'], ['undo', 'abcdef']], 'abcdef', 6], [[['insert', '!']], 'secret!', 7], [[['insert', 'x'], ['remove', ''], ['remove', 'x'], ['undo', 'x']], 'x', 0], [[], '', 0]], 2: [[[['insert', 'abcdabcd'], ['insert', 'XY'], ['remove', 'XY'], ['undo', 'abXYcdabcd'], ['undo', 'abcdabcd']], 'abcdabcd', 2], [[['insert', 'abcdefabcdef'], ['remove', 'cd']], 'abefabcdef', 2], [[['insert', 'abcdefabcdef'], ['remove', 'cd']], 'abefabcdef', 2], [[['insert', 'abcdefabcdef'], ['replace', 'cde', 'Z']], 'abZfabcdef', 3], [[['insert', 'abcdefabcdef'], ['replace', 'cde', 'Z'], ['undo', 'abcdefabcdef']], 'abcdefabcdef', 12], [[['insert', '!']], 'secretsecret!', 13], [[['insert', 'xx'], ['remove', ''], ['remove', 'xx'], ['undo', 'xx']], 'xx', 0], [[], '', 0]], 3: [[[['insert', 'abcdabcdabcd'], ['insert', 'XY'], ['remove', 'XY'], ['undo', 'abXYcdabcdabcd'], ['undo', 'abcdabcdabcd']], 'abcdabcdabcd', 2], [[['insert', 'abcdefabcdefabcdef'], ['remove', 'cd']], 'abefabcdefabcdef', 2], [[['insert', 'abcdefabcdefabcdef'], ['remove', 'cd']], 'abefabcdefabcdef', 2], [[['insert', 'abcdefabcdefabcdef'], ['replace', 'cde', 'Z']], 'abZfabcdefabcdef', 3], [[['insert', 'abcdefabcdefabcdef'], ['replace', 'cde', 'Z'], ['undo', 'abcdefabcdefabcdef']], 'abcdefabcdefabcdef', 18], [[['insert', '!']], 'secretsecretsecret!', 19], [[['insert', 'xxx'], ['remove', ''], ['remove', 'xxx'], ['undo', 'xxx']], 'xxx', 0], [[], '', 0]], 4: [[[['insert', 'abcdabcdabcdabcd'], ['insert', 'XY'], ['remove', 'XY'], ['undo', 'abXYcdabcdabcdabcd'], ['undo', 'abcdabcdabcdabcd']], 'abcdabcdabcdabcd', 2], [[['insert', 'abcdefabcdefabcdefabcdef'], ['remove', 'cd']], 'abefabcdefabcdefabcdef', 2], [[['insert', 'abcdefabcdefabcdefabcdef'], ['remove', 'cd']], 'abefabcdefabcdefabcdef', 2], [[['insert', 'abcdefabcdefabcdefabcdef'], ['replace', 'cde', 'Z']], 'abZfabcdefabcdefabcdef', 3], [[['insert', 'abcdefabcdefabcdefabcdef'], ['replace', 'cde', 'Z'], ['undo', 'abcdefabcdefabcdefabcdef']], 'abcdefabcdefabcdefabcdef', 24], [[['insert', '!']], 'secretsecretsecretsecret!', 25], [[['insert', 'xxxx'], ['remove', ''], ['remove', 'xxxx'], ['undo', 'xxxx']], 'xxxx', 0], [[], '', 0]], 5: [[[['insert', 'abcdabcdabcdabcdabcd'], ['insert', 'XY'], ['remove', 'XY'], ['undo', 'abXYcdabcdabcdabcdabcd'], ['undo', 'abcdabcdabcdabcdabcd']], 'abcdabcdabcdabcdabcd', 2], [[['insert', 'abcdefabcdefabcdefabcdefabcdef'], ['remove', 'cd']], 'abefabcdefabcdefabcdefabcdef', 2], [[['insert', 'abcdefabcdefabcdefabcdefabcdef'], ['remove', 'cd']], 'abefabcdefabcdefabcdefabcdef', 2], [[['insert', 'abcdefabcdefabcdefabcdefabcdef'], ['replace', 'cde', 'Z']], 'abZfabcdefabcdefabcdefabcdef', 3], [[['insert', 'abcdefabcdefabcdefabcdefabcdef'], ['replace', 'cde', 'Z'], ['undo', 'abcdefabcdefabcdefabcdefabcdef']], 'abcdefabcdefabcdefabcdefabcdef', 30], [[['insert', '!']], 'secretsecretsecretsecretsecret!', 31], [[['insert', 'xxxxx'], ['remove', ''], ['remove', 'xxxxx'], ['undo', 'xxxxx']], 'xxxxx', 0], [[], '', 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 | [[['insert', 'abcd'], ['insert', 'XY'], ['remove', 'XY'], ['undo', 'abcXYd'], ['undo', 'abcd']], 'abcd', 3] | [[['insert', 'abcd'], ['insert', 'XY'], ['remove', 'XY'], ['undo', 'abXYcd'], ['undo', 'abcd']], 'abcd', 2] | Failed |
| trace-2 | [[['insert', 'abcdef'], ['remove', 'de']], 'abcf', 3] | [[['insert', 'abcdef'], ['remove', 'cd']], 'abef', 2] | Failed |
| trace-3 | [[['insert', 'abcdef'], ['remove', 'de']], 'abcf', 3] | [[['insert', 'abcdef'], ['remove', 'cd']], 'abef', 2] | Failed |
| trace-4 | [[['insert', 'abcdef'], ['replace', 'cde', 'Z']], 'abZf', 3] | [[['insert', 'abcdef'], ['replace', 'cde', 'Z']], 'abZf', 3] | Passed |
| trace-5 | [[['insert', 'abcdef'], ['replace', 'cde', 'Z'], ['undo', 'abcdef']], 'abcdef', 6] | [[['insert', 'abcdef'], ['replace', 'cde', 'Z'], ['undo', 'abcdef']], 'abcdef', 6] | Passed |
| trace-6 | [[['insert', '!']], 'secret!', 7] | [[['insert', '!']], 'secret!', 7] | Passed |
| trace-7 | [[['insert', 'x'], ['remove', ''], ['remove', 'x'], ['undo', 'x']], 'x', 0] | [[['insert', 'x'], ['remove', ''], ['remove', 'x'], ['undo', 'x']], 'x', 0] | Passed |
| trace-8 | [[], '', 0] | [[], '', 0] | Passed |
SHA-256 / 7100628504351f73973ef029c1c4e2d9b9b736c252af3ec7a2d5760e3534a12f
HELD IN THE MEMBER ARCHIVE
The verified repair and its recorded checks are member-only.
This mechanism has 8 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.
Member access is invitation-based. Sign in with your invited account to inspect the repair.
Sign in to the archive ↗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 2026-09-29T14:40:28.856990+00:00.
Case digest / 43d145f47469e76d222c82cc3e7d32896e76a603967e61b2e146baa8e6f469d0