FA-9016 / Keyboard interactions / Open access

Scoped keyboard shortcut dispatch: Global undo intercepts editing inside text fields · case 01

Global undo intercepts editing inside text fields.

Verified by executionVariant 1 · 9 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

The editable operation uses `if False: return None` where the contract requires `if editable: return None`.

VERIFIED REPAIR

Implement the editable operation as `if editable: return None`.

Unsuccessful approach: Blocking only noneditable contexts reverses scope protection.

Case contract

Ignore prevented, repeated, and editable-origin events; use platform primary modifier; Alt blocks shortcuts; Shift-Z redoes, Z undoes, unshifted S saves.

Why this case matters

A deterministic model of scoped keyboard shortcut dispatch; this isolates one interface invariant without requiring a browser.

1 / The failure

Exit 1

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

N = 1
observations = []
def solve(key, ctrl, meta, alt, shift, platform, editable, repeat, prevented):
    if prevented or repeat: return None
    if False: return None
    primary = meta if platform == 'mac' else ctrl
    if not primary or alt: return None
    if key.lower() == 'z': return 'redo' if shift else 'undo'
    if key.lower() == 's' and not shift: return 'save'
    return None
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('prevented', solve('z', True, False, False, False, 'win', False, False, True), None)
check('repeat', solve('z', True, False, False, False, 'win', False, True, False), None)
check('editable', solve('z', True, False, False, False, 'win', True, False, False), None)
check('mac', solve('z', False, True, False, False, 'mac', False, False, False), 'undo')
check('win', solve('z', True, False, False, False, 'win', False, False, False), 'undo')
check('redo', solve('z', True, False, False, True, 'win', False, False, False), 'redo')
check('alt', solve('z', True, False, True, False, 'win', False, False, False), None)
check('parameterized target context', solve('z',True,False,False,False,'win',bool(N%2),False,False), None if N%2 else 'undo')
for repetition in range(N):
    check('repeat alt', solve('z', True, False, True, False, 'win', False, False, False), None)
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
prevented	`None`	`None`	Passed
repeat	`None`	`None`	Passed
editable	`undo`	`None`	Failed
mac	`undo`	`undo`	Passed
win	`undo`	`undo`	Passed
redo	`redo`	`redo`	Passed
alt	`None`	`None`	Passed
parameterized target context	`undo`	`None`	Failed
repeat alt	`None`	`None`	Passed

SHA-256 / 21dc80c69680c1cdec18e60110ba5e7ff70b73f49d5ffd762593da0d48cba7f9

2 / The unsuccessful fix

Exit 1

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

N = 1
observations = []
def solve(key, ctrl, meta, alt, shift, platform, editable, repeat, prevented):
    if prevented or repeat: return None
    if not editable: return None
    primary = meta if platform == 'mac' else ctrl
    if not primary or alt: return None
    if key.lower() == 'z': return 'redo' if shift else 'undo'
    if key.lower() == 's' and not shift: return 'save'
    return None
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('prevented', solve('z', True, False, False, False, 'win', False, False, True), None)
check('repeat', solve('z', True, False, False, False, 'win', False, True, False), None)
check('editable', solve('z', True, False, False, False, 'win', True, False, False), None)
check('mac', solve('z', False, True, False, False, 'mac', False, False, False), 'undo')
check('win', solve('z', True, False, False, False, 'win', False, False, False), 'undo')
check('redo', solve('z', True, False, False, True, 'win', False, False, False), 'redo')
check('alt', solve('z', True, False, True, False, 'win', False, False, False), None)
check('parameterized target context', solve('z',True,False,False,False,'win',bool(N%2),False,False), None if N%2 else 'undo')
for repetition in range(N):
    check('repeat alt', solve('z', True, False, True, False, 'win', False, False, False), None)
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
prevented	`None`	`None`	Passed
repeat	`None`	`None`	Passed
editable	`undo`	`None`	Failed
mac	`None`	`undo`	Failed
win	`None`	`undo`	Failed
redo	`None`	`redo`	Failed
alt	`None`	`None`	Passed
parameterized target context	`undo`	`None`	Failed
repeat alt	`None`	`None`	Passed

SHA-256 / cb804983643860fa3cca9524f6bbf0b63f530ca7537816d4367fe251b8ac8b80

3 / The verified repair

Exit 0

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

N = 1
observations = []
def solve(key, ctrl, meta, alt, shift, platform, editable, repeat, prevented):
    if prevented or repeat: return None
    if editable: return None
    primary = meta if platform == 'mac' else ctrl
    if not primary or alt: return None
    if key.lower() == 'z': return 'redo' if shift else 'undo'
    if key.lower() == 's' and not shift: return 'save'
    return None
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('prevented', solve('z', True, False, False, False, 'win', False, False, True), None)
check('repeat', solve('z', True, False, False, False, 'win', False, True, False), None)
check('editable', solve('z', True, False, False, False, 'win', True, False, False), None)
check('mac', solve('z', False, True, False, False, 'mac', False, False, False), 'undo')
check('win', solve('z', True, False, False, False, 'win', False, False, False), 'undo')
check('redo', solve('z', True, False, False, True, 'win', False, False, False), 'redo')
check('alt', solve('z', True, False, True, False, 'win', False, False, False), None)
check('parameterized target context', solve('z',True,False,False,False,'win',bool(N%2),False,False), None if N%2 else 'undo')
for repetition in range(N):
    check('repeat alt', solve('z', True, False, True, False, 'win', False, False, False), None)
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
prevented	`None`	`None`	Passed
repeat	`None`	`None`	Passed
editable	`None`	`None`	Passed
mac	`undo`	`undo`	Passed
win	`undo`	`undo`	Passed
redo	`redo`	`redo`	Passed
alt	`None`	`None`	Passed
parameterized target context	`None`	`None`	Passed
repeat alt	`None`	`None`	Passed

SHA-256 / 57e8128ff05fe833f1456d79a412d1065dd2e5fcb142e213a048dee71ea1c567

Verification & scope

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 2026-09-29T14:38:26.294196+00:00.

Case digest / 0b87a5b986d2ba4e0094e3dd07763a6299053529366b56ae68382906df2ac694