FA-31676 / Keyboard interactions / Open access

Per-switch keyboard scan debounce: Committed switch level disagrees with its emitted edge · case 01

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

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

ROOT CAUSE

Committed switch level disagrees with its emitted edge.

THE FAILURE

Committed switch level disagrees with its emitted edge.

Unsuccessful approach: The partial repair changes this transition to stable[key]=True, which still violates the model contract on the explicit regression traces.

Case contract

Case [threshold,scans]. Each scan is [time,sorted_pressed_keys] and times increase. A raw transition starts a candidate timer; a candidate becomes stable after continuously present for threshold time including exact boundary. Each scan considers every known or raw key. Emit [key,down_or_up,time] on stable transitions; return emissions plus stable pressed keys. Missing keys are raw up. 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):
        threshold,scans=c
        stable={}; candidate={}; since={}; output=[]
        for now,pressed in scans:
            raw=set(pressed)
            keys=sorted(set(stable)|set(candidate)|raw)
            for key in keys:
                value=key in raw
                if key not in candidate or candidate[key]!=value:
                    candidate[key]=value
                    since[key]=now
                if now-since[key]>=threshold and stable.get(key,False)!=value:
                    stable[key]=not value
                    output.append([key,'down' if value else 'up',now])
        return [output,sorted(k for k,v in stable.items() if v)]
    return [run(c) for c in cases]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('key-debounce scenario 0', solve([[3, []]] * N), [[[], []]] * N)
check('key-debounce scenario 1', solve([[3, [[10, ['A']], [12, ['A']], [13, ['A']], [14, ['A']]]]] * N), [[[['A', 'down', 13]], ['A']]] * N)
check('key-debounce scenario 2', solve([[3, [[10, ['A']], [13, ['A']], [14, []], [17, []]]]] * N), [[[['A', 'down', 13], ['A', 'up', 17]], []]] * N)
check('key-debounce scenario 3', solve([[3, [[10, ['A']], [11, []], [12, ['A']], [14, ['A']], [15, ['A']]]]] * N), [[[['A', 'down', 15]], ['A']]] * N)
check('key-debounce scenario 4', solve([[3, [[10, ['A']], [13, ['A']], [14, ['B']], [17, ['B']]]]] * N), [[[['A', 'down', 13], ['A', 'up', 17], ['B', 'down', 17]], ['B']]] * N)
check('key-debounce scenario 5', solve([[3, [[10, ['A']], [11, []], [14, []]]]] * N), [[[], []]] * N)
check('key-debounce scenario 6', solve([[3, [[10, []], [20, ['A', 'B']], [23, ['A', 'B']], [24, ['B']], [27, ['B']]]]] * N), [[[['A', 'down', 23], ['B', 'down', 23], ['A', 'up', 27]], ['B']]] * N)
check('key-debounce scenario 7', solve([[3, [[10, ['A']], [13, ['A']], [14, []], [15, ['A']], [18, ['A']]]]] * N), [[[['A', 'down', 13]], ['A']]] * 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 fixture	Actual	Expected	Outcome
key-debounce scenario 0	`[[[], []]]`	`[[[], []]]`	Passed
key-debounce scenario 1	`[[[['A', 'down', 13], ['A', 'down', 14]], []]]`	`[[[['A', 'down', 13]], ['A']]]`	Failed
key-debounce scenario 2	`[[[['A', 'down', 13]], []]]`	`[[[['A', 'down', 13], ['A', 'up', 17]], []]]`	Failed
key-debounce scenario 3	`[[[['A', 'down', 15]], []]]`	`[[[['A', 'down', 15]], ['A']]]`	Failed
key-debounce scenario 4	`[[[['A', 'down', 13], ['B', 'down', 17]], []]]`	`[[[['A', 'down', 13], ['A', 'up', 17], ['B', 'down', 17]], ['B']]]`	Failed
key-debounce scenario 5	`[[[], []]]`	`[[[], []]]`	Passed
key-debounce scenario 6	`[[[['A', 'down', 23], ['B', 'down', 23], ['B', 'down', 24], ['B', 'down', 27]], []]]`	`[[[['A', 'down', 23], ['B', 'down', 23], ['A', 'up', 27]], ['B']]]`	Failed
key-debounce scenario 7	`[[[['A', 'down', 13], ['A', 'down', 18]], []]]`	`[[[['A', 'down', 13]], ['A']]]`	Failed

SHA-256 / a426f357536ad45d7f954d7a8921963b5452442492de5f2cce9b17328e8ab84e

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):
        threshold,scans=c
        stable={}; candidate={}; since={}; output=[]
        for now,pressed in scans:
            raw=set(pressed)
            keys=sorted(set(stable)|set(candidate)|raw)
            for key in keys:
                value=key in raw
                if key not in candidate or candidate[key]!=value:
                    candidate[key]=value
                    since[key]=now
                if now-since[key]>=threshold and stable.get(key,False)!=value:
                    stable[key]=True
                    output.append([key,'down' if value else 'up',now])
        return [output,sorted(k for k,v in stable.items() if v)]
    return [run(c) for c in cases]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('key-debounce scenario 0', solve([[3, []]] * N), [[[], []]] * N)
check('key-debounce scenario 1', solve([[3, [[10, ['A']], [12, ['A']], [13, ['A']], [14, ['A']]]]] * N), [[[['A', 'down', 13]], ['A']]] * N)
check('key-debounce scenario 2', solve([[3, [[10, ['A']], [13, ['A']], [14, []], [17, []]]]] * N), [[[['A', 'down', 13], ['A', 'up', 17]], []]] * N)
check('key-debounce scenario 3', solve([[3, [[10, ['A']], [11, []], [12, ['A']], [14, ['A']], [15, ['A']]]]] * N), [[[['A', 'down', 15]], ['A']]] * N)
check('key-debounce scenario 4', solve([[3, [[10, ['A']], [13, ['A']], [14, ['B']], [17, ['B']]]]] * N), [[[['A', 'down', 13], ['A', 'up', 17], ['B', 'down', 17]], ['B']]] * N)
check('key-debounce scenario 5', solve([[3, [[10, ['A']], [11, []], [14, []]]]] * N), [[[], []]] * N)
check('key-debounce scenario 6', solve([[3, [[10, []], [20, ['A', 'B']], [23, ['A', 'B']], [24, ['B']], [27, ['B']]]]] * N), [[[['A', 'down', 23], ['B', 'down', 23], ['A', 'up', 27]], ['B']]] * N)
check('key-debounce scenario 7', solve([[3, [[10, ['A']], [13, ['A']], [14, []], [15, ['A']], [18, ['A']]]]] * N), [[[['A', 'down', 13]], ['A']]] * 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 fixture	Actual	Expected	Outcome
key-debounce scenario 0	`[[[], []]]`	`[[[], []]]`	Passed
key-debounce scenario 1	`[[[['A', 'down', 13]], ['A']]]`	`[[[['A', 'down', 13]], ['A']]]`	Passed
key-debounce scenario 2	`[[[['A', 'down', 13], ['A', 'up', 17]], ['A']]]`	`[[[['A', 'down', 13], ['A', 'up', 17]], []]]`	Failed
key-debounce scenario 3	`[[[['A', 'down', 15]], ['A']]]`	`[[[['A', 'down', 15]], ['A']]]`	Passed
key-debounce scenario 4	`[[[['A', 'down', 13], ['A', 'up', 17], ['B', 'down', 17]], ['A', 'B']]]`	`[[[['A', 'down', 13], ['A', 'up', 17], ['B', 'down', 17]], ['B']]]`	Failed
key-debounce scenario 5	`[[[], []]]`	`[[[], []]]`	Passed
key-debounce scenario 6	`[[[['A', 'down', 23], ['B', 'down', 23], ['A', 'up', 27]], ['A', 'B']]]`	`[[[['A', 'down', 23], ['B', 'down', 23], ['A', 'up', 27]], ['B']]]`	Failed
key-debounce scenario 7	`[[[['A', 'down', 13]], ['A']]]`	`[[[['A', 'down', 13]], ['A']]]`	Passed

SHA-256 / 5b207895c11a08cda47199e65a8b1dba820b57d221d6bdb0f5ada6f9c445a933

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 2026-09-29T14:42:04.626076+00:00.

Case digest / c04d82abdd37fb90da6bb6ba8a3e01c1365d42bc4e0059e0f4dd29d0106f1d6a