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FA-31921 / Keyboard interactions / Open access

Release-completed dot chord keyboard: Dot chord commits before all participating keys have been released · case 01

The event trace violates the commit final rule and produces incorrect keyboard state or command output.

Verified by executionVariant 1 · 11 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

Dot chord commits before all participating keys have been released.

THE FAILURE

Dot chord commits before all participating keys have been released.

Unsuccessful approach: The partial repair changes this transition to if len(held)<=1 and chord:, which still violates the model contract on the explicit regression traces.

Case contract

Events [kind,dot]. Dot values 1..8. Down adds a dot to held and accumulated chord; repeated down does not add another dot. Up releases a held dot and commits sorted accumulated dots only when the final held dot is released. Cancel clears held/chord without output; separator commits pending chord then emits empty dot list and resets. Return committed dot lists, held and accumulated sets. 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):
        held=set(); chord=set(); out=[]; ignored=0
        for kind,dot in c:
            if kind in ('down','up') and not 1<=dot<=8:
                ignored+=1
                continue
            if kind=='down':
                held.add(dot)
                chord.add(dot)
            elif kind=='up' and dot in held:
                held.discard(dot)
                if chord:
                    out.append(sorted(chord))
                    chord.clear()
            elif kind=='up': ignored+=1
            elif kind=='cancel':
                held.clear(); chord.clear()
            elif kind=='separator':
                if chord: out.append(sorted(chord))
                out.append([])
                held.clear(); chord.clear()
        return [out,sorted(held),sorted(chord),ignored]
    return [run(c) for c in cases]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('braille-chord scenario 0', solve([[]] * N), [[[], [], [], 0]] * N)
check('braille-chord scenario 1', solve([[['down', 1], ['down', 2]]] * N), [[[], [1, 2], [1, 2], 0]] * N)
check('braille-chord scenario 2', solve([[['down', 1], ['down', 8], ['up', 1], ['up', 8]]] * N), [[[[1, 8]], [], [], 0]] * N)
check('braille-chord scenario 3', solve([[['down', 2], ['down', 2], ['up', 2]]] * N), [[[[2]], [], [], 0]] * N)
check('braille-chord scenario 4', solve([[['down', 1], ['down', 2], ['up', 1]]] * N), [[[], [2], [1, 2], 0]] * N)
check('braille-chord scenario 5', solve([[['down', 1], ['up', 1], ['down', 2], ['up', 2]]] * N), [[[[1], [2]], [], [], 0]] * N)
check('braille-chord scenario 6', solve([[['down', 2], ['up', 3]]] * N), [[[], [2], [2], 1]] * N)
check('braille-chord scenario 7', solve([[['down', 0], ['up', 0], ['down', 9]]] * N), [[[], [], [], 3]] * N)
check('braille-chord scenario 8', solve([[['down', 1], ['down', 2], ['separator', 0]]] * N), [[[[1, 2], []], [], [], 0]] * N)
check('braille-chord scenario 9', solve([[['separator', 0]]] * N), [[[[]], [], [], 0]] * N)
check('braille-chord scenario 10', solve([[['down', 1], ['cancel', 0], ['up', 1]]] * N), [[[], [], [], 1]] * 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
braille-chord scenario 0[[[], [], [], 0]][[[], [], [], 0]]Passed
braille-chord scenario 1[[[], [1, 2], [1, 2], 0]][[[], [1, 2], [1, 2], 0]]Passed
braille-chord scenario 2[[[[1, 8]], [], [], 0]][[[[1, 8]], [], [], 0]]Passed
braille-chord scenario 3[[[[2]], [], [], 0]][[[[2]], [], [], 0]]Passed
braille-chord scenario 4[[[[1, 2]], [2], [], 0]][[[], [2], [1, 2], 0]]Failed
braille-chord scenario 5[[[[1], [2]], [], [], 0]][[[[1], [2]], [], [], 0]]Passed
braille-chord scenario 6[[[], [2], [2], 1]][[[], [2], [2], 1]]Passed
braille-chord scenario 7[[[], [], [], 3]][[[], [], [], 3]]Passed
braille-chord scenario 8[[[[1, 2], []], [], [], 0]][[[[1, 2], []], [], [], 0]]Passed
braille-chord scenario 9[[[[]], [], [], 0]][[[[]], [], [], 0]]Passed
braille-chord scenario 10[[[], [], [], 1]][[[], [], [], 1]]Passed

SHA-256 / 079a719ee8c684fb2a5cf008bdd2812a5dff9c0cff93d0e318c4d7f7b3786b6a

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):
        held=set(); chord=set(); out=[]; ignored=0
        for kind,dot in c:
            if kind in ('down','up') and not 1<=dot<=8:
                ignored+=1
                continue
            if kind=='down':
                held.add(dot)
                chord.add(dot)
            elif kind=='up' and dot in held:
                held.discard(dot)
                if len(held)<=1 and chord:
                    out.append(sorted(chord))
                    chord.clear()
            elif kind=='up': ignored+=1
            elif kind=='cancel':
                held.clear(); chord.clear()
            elif kind=='separator':
                if chord: out.append(sorted(chord))
                out.append([])
                held.clear(); chord.clear()
        return [out,sorted(held),sorted(chord),ignored]
    return [run(c) for c in cases]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('braille-chord scenario 0', solve([[]] * N), [[[], [], [], 0]] * N)
check('braille-chord scenario 1', solve([[['down', 1], ['down', 2]]] * N), [[[], [1, 2], [1, 2], 0]] * N)
check('braille-chord scenario 2', solve([[['down', 1], ['down', 8], ['up', 1], ['up', 8]]] * N), [[[[1, 8]], [], [], 0]] * N)
check('braille-chord scenario 3', solve([[['down', 2], ['down', 2], ['up', 2]]] * N), [[[[2]], [], [], 0]] * N)
check('braille-chord scenario 4', solve([[['down', 1], ['down', 2], ['up', 1]]] * N), [[[], [2], [1, 2], 0]] * N)
check('braille-chord scenario 5', solve([[['down', 1], ['up', 1], ['down', 2], ['up', 2]]] * N), [[[[1], [2]], [], [], 0]] * N)
check('braille-chord scenario 6', solve([[['down', 2], ['up', 3]]] * N), [[[], [2], [2], 1]] * N)
check('braille-chord scenario 7', solve([[['down', 0], ['up', 0], ['down', 9]]] * N), [[[], [], [], 3]] * N)
check('braille-chord scenario 8', solve([[['down', 1], ['down', 2], ['separator', 0]]] * N), [[[[1, 2], []], [], [], 0]] * N)
check('braille-chord scenario 9', solve([[['separator', 0]]] * N), [[[[]], [], [], 0]] * N)
check('braille-chord scenario 10', solve([[['down', 1], ['cancel', 0], ['up', 1]]] * N), [[[], [], [], 1]] * 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
braille-chord scenario 0[[[], [], [], 0]][[[], [], [], 0]]Passed
braille-chord scenario 1[[[], [1, 2], [1, 2], 0]][[[], [1, 2], [1, 2], 0]]Passed
braille-chord scenario 2[[[[1, 8]], [], [], 0]][[[[1, 8]], [], [], 0]]Passed
braille-chord scenario 3[[[[2]], [], [], 0]][[[[2]], [], [], 0]]Passed
braille-chord scenario 4[[[[1, 2]], [2], [], 0]][[[], [2], [1, 2], 0]]Failed
braille-chord scenario 5[[[[1], [2]], [], [], 0]][[[[1], [2]], [], [], 0]]Passed
braille-chord scenario 6[[[], [2], [2], 1]][[[], [2], [2], 1]]Passed
braille-chord scenario 7[[[], [], [], 3]][[[], [], [], 3]]Passed
braille-chord scenario 8[[[[1, 2], []], [], [], 0]][[[[1, 2], []], [], [], 0]]Passed
braille-chord scenario 9[[[[]], [], [], 0]][[[[]], [], [], 0]]Passed
braille-chord scenario 10[[[], [], [], 1]][[[], [], [], 1]]Passed

SHA-256 / acaff866b85b16c6e11a2cf263d609df7f844233b6468670895234d4e6cc706c

HELD IN THE MEMBER ARCHIVE

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

This mechanism has 11 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 2026-09-29T14:42:07.070069+00:00.

Case digest / 1ea0ce98a2bdc05a3b69680b57403a25b68c3a5ecbe1a73fd56e78992ee8ed6a