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FA-32066 / Keyboard interactions / Open access

Composition replacement against document revisions: Stale composition replacement overwrites a newer document revision · case 01

The event trace violates the conflict compare rule and produces incorrect keyboard state or command output.

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

ROOT CAUSE

Stale composition replacement overwrites a newer document revision.

THE FAILURE

Stale composition replacement overwrites a newer document revision.

Unsuccessful approach: The partial repair changes this transition to if base!=revision:, which still violates the model contract on the explicit regression traces.

Case contract

Case [document,revision,events]. Events [kind,a,b,text]. Begin captures valid range [a,b) and current revision with preedit text; update replaces pending preedit; external replaces entire document and increments revision. Commit applies pending replacement only if captured revision still equals current, otherwise counts stale conflict; either path closes pending. Cancel discards pending. Return document, revision, pending [lo,hi,base,text] or None, conflicts. Inputs are finite ordered event traces; return the stated deterministic state. Batch entries are independent. N varies the number of independent input transactions.

Why this case matters

Controlled keyboard event processing model for debugging application event logic.

1 / The failure

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

N = 1
observations = []
def solve(cases):
    def run(c):
        document,revision,events=c
        pending=None; conflicts=0
        for kind,a,b,text in events:
            if kind=='begin': pending=[a,b,revision,text]
            elif kind=='update' and pending is not None: pending[3]=text
            elif kind=='external': document=text; revision+=1
            elif kind=='commit' and pending is not None:
                lo,hi,base,preedit=pending
                if base<=revision:
                    document=document[:lo]+preedit+document[hi:]
                    revision+=1
                else: conflicts+=1
                pending=None
            elif kind=='cancel': pending=None
        return [document,revision,pending,conflicts]
    return [run(c) for c in cases]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('composition-revision scenario 0', solve([['abcd', 4, []]] * N), [['abcd', 4, None, 0]] * N)
check('composition-revision scenario 1', solve([['abcd', 4, [['begin', 1, 3, 'X'], ['commit', 0, 0, '']]]] * N), [['aXd', 5, None, 0]] * N)
check('composition-revision scenario 2', solve([['abcd', 4, [['begin', 1, 3, 'X'], ['update', 0, 0, 'YZ'], ['commit', 0, 0, '']]]] * N), [['aYZd', 5, None, 0]] * N)
check('composition-revision scenario 3', solve([['abcd', 4, [['begin', 1, 3, 'X'], ['external', 0, 0, 'new'], ['commit', 0, 0, '']]]] * N), [['new', 5, None, 1]] * N)
check('composition-revision scenario 4', solve([['abcd', 4, [['external', 0, 0, 'one'], ['external', 0, 0, 'two']]]] * N), [['two', 6, None, 0]] * N)
check('composition-revision scenario 5', solve([['abcd', 4, [['begin', 1, 3, 'X'], ['external', 0, 0, 'one'], ['external', 0, 0, 'two'], ['commit', 0, 0, ''], ['begin', 0, 1, 'Z'], ['external', 0, 0, 'three'], ['commit', 0, 0, '']]]] * N), [['three', 7, None, 2]] * N)
check('composition-revision scenario 6', solve([['abcd', 4, [['begin', 0, 0, ''], ['cancel', 0, 0, '']]]] * N), [['abcd', 4, None, 0]] * N)
check('composition-revision scenario 7', solve([['abcd', 0, [['begin', 1, 3, 'X'], ['commit', 0, 0, ''], ['commit', 0, 0, '']]]] * N), [['aXd', 1, None, 0]] * N)
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
composition-revision scenario 0[['abcd', 4, None, 0]][['abcd', 4, None, 0]]Passed
composition-revision scenario 1[['aXd', 5, None, 0]][['aXd', 5, None, 0]]Passed
composition-revision scenario 2[['aYZd', 5, None, 0]][['aYZd', 5, None, 0]]Passed
composition-revision scenario 3[['nX', 6, None, 0]][['new', 5, None, 1]]Failed
composition-revision scenario 4[['two', 6, None, 0]][['two', 6, None, 0]]Passed
composition-revision scenario 5[['Zhree', 9, None, 0]][['three', 7, None, 2]]Failed
composition-revision scenario 6[['abcd', 4, None, 0]][['abcd', 4, None, 0]]Passed
composition-revision scenario 7[['aXd', 1, None, 0]][['aXd', 1, None, 0]]Passed

SHA-256 / 29127ca78f31788dfb061311e90ce8ffe38cc23cdb996c2f60093eb1b5fad2c7

2 / The unsuccessful fix

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

N = 1
observations = []
def solve(cases):
    def run(c):
        document,revision,events=c
        pending=None; conflicts=0
        for kind,a,b,text in events:
            if kind=='begin': pending=[a,b,revision,text]
            elif kind=='update' and pending is not None: pending[3]=text
            elif kind=='external': document=text; revision+=1
            elif kind=='commit' and pending is not None:
                lo,hi,base,preedit=pending
                if base!=revision:
                    document=document[:lo]+preedit+document[hi:]
                    revision+=1
                else: conflicts+=1
                pending=None
            elif kind=='cancel': pending=None
        return [document,revision,pending,conflicts]
    return [run(c) for c in cases]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('composition-revision scenario 0', solve([['abcd', 4, []]] * N), [['abcd', 4, None, 0]] * N)
check('composition-revision scenario 1', solve([['abcd', 4, [['begin', 1, 3, 'X'], ['commit', 0, 0, '']]]] * N), [['aXd', 5, None, 0]] * N)
check('composition-revision scenario 2', solve([['abcd', 4, [['begin', 1, 3, 'X'], ['update', 0, 0, 'YZ'], ['commit', 0, 0, '']]]] * N), [['aYZd', 5, None, 0]] * N)
check('composition-revision scenario 3', solve([['abcd', 4, [['begin', 1, 3, 'X'], ['external', 0, 0, 'new'], ['commit', 0, 0, '']]]] * N), [['new', 5, None, 1]] * N)
check('composition-revision scenario 4', solve([['abcd', 4, [['external', 0, 0, 'one'], ['external', 0, 0, 'two']]]] * N), [['two', 6, None, 0]] * N)
check('composition-revision scenario 5', solve([['abcd', 4, [['begin', 1, 3, 'X'], ['external', 0, 0, 'one'], ['external', 0, 0, 'two'], ['commit', 0, 0, ''], ['begin', 0, 1, 'Z'], ['external', 0, 0, 'three'], ['commit', 0, 0, '']]]] * N), [['three', 7, None, 2]] * N)
check('composition-revision scenario 6', solve([['abcd', 4, [['begin', 0, 0, ''], ['cancel', 0, 0, '']]]] * N), [['abcd', 4, None, 0]] * N)
check('composition-revision scenario 7', solve([['abcd', 0, [['begin', 1, 3, 'X'], ['commit', 0, 0, ''], ['commit', 0, 0, '']]]] * N), [['aXd', 1, None, 0]] * N)
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
composition-revision scenario 0[['abcd', 4, None, 0]][['abcd', 4, None, 0]]Passed
composition-revision scenario 1[['abcd', 4, None, 1]][['aXd', 5, None, 0]]Failed
composition-revision scenario 2[['abcd', 4, None, 1]][['aYZd', 5, None, 0]]Failed
composition-revision scenario 3[['nX', 6, None, 0]][['new', 5, None, 1]]Failed
composition-revision scenario 4[['two', 6, None, 0]][['two', 6, None, 0]]Passed
composition-revision scenario 5[['Zhree', 9, None, 0]][['three', 7, None, 2]]Failed
composition-revision scenario 6[['abcd', 4, None, 0]][['abcd', 4, None, 0]]Passed
composition-revision scenario 7[['abcd', 0, None, 1]][['aXd', 1, None, 0]]Failed

SHA-256 / aae8a84459d3c7c50742f2d1bec5eb589f26a323d83b1d4932d23700bf0774b7

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.

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Verification & scope

Offline stipulated event model, not a browser implementation or web standard 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 2026-09-29T14:42:08.541593+00:00.

Case digest / 8db5a56d0c9bc4ec6b7d717450161aef4148aa8d9cb96a385702366645aa4174