FA-11781 / Localization message semantics / Open access

Unselected message branches demand unavailable variables · case 01

Unselected message branches demand unavailable variables.

Verified by executionVariant 1 · 7 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

All branch templates are formatted before selecting the active message.

VERIFIED REPAIR

The named branch or other must exist. Select the named branch if present, otherwise other, then format only that branch with str.format. Return missing only if the selected branch requires an absent argument.

Unsuccessful approach: Checking all branches for missing arguments before selection retains the same eager requirement.

Case contract

Why this case matters

This offline controlled message model isolates a localization decision; it does not implement a complete message-format or locale standard.

1 / The failure

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json
import re
N = 1
observations = []
def solve(branches, choice, values):
    try:
        rendered = {k:v.format(**values) for k,v in branches.items()}
        return rendered.get(choice,rendered['other'])
    except KeyError: return 'missing'
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('explicit branch without default', solve({'special':'ok'},'special',{}), 'ok')
check('inactive missing', solve({'special':'{secret}','other':'Hello {name}'},'other',{'name':str(N)}), 'Hello '+str(N))
check('chosen complete', solve({'special':'{secret}','other':'{name}'},'special',{'secret':'yes'}), 'yes')
check('selected missing', solve({'other':'{name}'},'other',{}), 'missing')
check('fallback', solve({'special':'{secret}','other':'ok'},'unknown',{}), 'ok')
check('constant', solve({'other':'ok'},'other',{}), 'ok')
check('supplied variables', solve({'special':'{secret}','other':'{name}'},'other',{'secret':'x','name':str(N)}), str(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
explicit branch without default	`missing`	`ok`	Failed
inactive missing	`missing`	`Hello 1`	Failed
chosen complete	`missing`	`yes`	Failed
selected missing	`missing`	`missing`	Passed
fallback	`missing`	`ok`	Failed
constant	`ok`	`ok`	Passed
supplied variables	`1`	`1`	Passed

SHA-256 / 2c57eb5e96be61f2715263cdb74676fd28f1e14fc95f14eca21f52e8eee7ecf4

2 / The unsuccessful fix

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json
import re
N = 1
observations = []
def solve(branches, choice, values):
    if any(name not in values for text in branches.values() for name in re.findall(r'\{([a-z]+)\}',text)): return 'missing'
    return (branches[choice] if choice in branches else branches.get('other','missing')).format(**values)
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('explicit branch without default', solve({'special':'ok'},'special',{}), 'ok')
check('inactive missing', solve({'special':'{secret}','other':'Hello {name}'},'other',{'name':str(N)}), 'Hello '+str(N))
check('chosen complete', solve({'special':'{secret}','other':'{name}'},'special',{'secret':'yes'}), 'yes')
check('selected missing', solve({'other':'{name}'},'other',{}), 'missing')
check('fallback', solve({'special':'{secret}','other':'ok'},'unknown',{}), 'ok')
check('constant', solve({'other':'ok'},'other',{}), 'ok')
check('supplied variables', solve({'special':'{secret}','other':'{name}'},'other',{'secret':'x','name':str(N)}), str(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
explicit branch without default	`ok`	`ok`	Passed
inactive missing	`missing`	`Hello 1`	Failed
chosen complete	`missing`	`yes`	Failed
selected missing	`missing`	`missing`	Passed
fallback	`missing`	`ok`	Failed
constant	`ok`	`ok`	Passed
supplied variables	`1`	`1`	Passed

SHA-256 / 95ce1c1c727f5e9defc589506464a633bc6ca1a8136679a42cd2f9bfdf567546

3 / The verified repair

Exit 0

"""Failure Map reference implementation. Python standard library only."""
import json
import re
N = 1
observations = []
def solve(branches, choice, values):
    try:
        template = branches[choice] if choice in branches else branches['other']
        return template.format(**values)
    except KeyError: return 'missing'
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('explicit branch without default', solve({'special':'ok'},'special',{}), 'ok')
check('inactive missing', solve({'special':'{secret}','other':'Hello {name}'},'other',{'name':str(N)}), 'Hello '+str(N))
check('chosen complete', solve({'special':'{secret}','other':'{name}'},'special',{'secret':'yes'}), 'yes')
check('selected missing', solve({'other':'{name}'},'other',{}), 'missing')
check('fallback', solve({'special':'{secret}','other':'ok'},'unknown',{}), 'ok')
check('constant', solve({'other':'ok'},'other',{}), 'ok')
check('supplied variables', solve({'special':'{secret}','other':'{name}'},'other',{'secret':'x','name':str(N)}), str(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
explicit branch without default	`ok`	`ok`	Passed
inactive missing	`Hello 1`	`Hello 1`	Passed
chosen complete	`yes`	`yes`	Passed
selected missing	`missing`	`missing`	Passed
fallback	`ok`	`ok`	Passed
constant	`ok`	`ok`	Passed
supplied variables	`1`	`1`	Passed

SHA-256 / 6a0e78d3460b7d117fc9c5b95198a93f46cda025d1d86b3f7015adc03ad015b2

Verification & scope

Only the explicitly specified miniature locale/message rules are modeled. 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 2026-09-29T14:38:50.965674+00:00.

Case digest / 096e82328ef8809707da11ba995d6bb78ff07535bd161fec524e812a7d7c41a3