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Environment variable projection: Optional absent variables become missing errors · case 01

Optional absent variables become missing errors.

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

ROOT CAUSE

The implementation substitutes elif True: for elif required:, so optional absent variables become missing errors.

VERIFIED REPAIR

Omit optional undeclared values.

Unsuccessful approach: The attempted repair substitutes elif not required:. Fixture 5 still yields {} instead of {'PORT': 'missing'}.

Case contract

For declared variable names return exact present environment value, otherwise explicit default including empty values. Required missing values report missing; optional missing values are omitted. Prefix is prepended before lookup.

Why this case matters

An offline model of environment variable projection, suitable for testing build and release tooling without external services.

1 / The failure

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

N = 1
observations = []
def solve(declarations, environment, prefix):
    result = {}
    for name, default, required in declarations:
        key = prefix + name
        if key in environment: result[name] = environment[key]
        elif default is not None: result[name] = default
        elif True: result[name] = 'missing'
    return result
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('fixture 1', solve([], {}, 'APP_'), {})
check('fixture 2', solve([('PORT', None, True)], {'APP_PORT': '0'}, 'APP_'), {'PORT': '0'})
check('fixture 3', solve([('PORT', '80', True)], {'APP_PORT': ''}, 'APP_'), {'PORT': ''})
check('fixture 4', solve([('PORT', '', True)], {}, 'APP_'), {'PORT': ''})
check('fixture 5', solve([('PORT', None, True)], {}, 'APP_'), {'PORT': 'missing'})
check('fixture 6', solve([('PORT', None, False)], {}, 'APP_'), {})
check('fixture 7', solve([('PORT', '80', False)], {}, 'APP_'), {'PORT': '80'})
check('fixture 8', solve([('PORT', '80', True)], {'PORT': '90'}, 'APP_'), {'PORT': '80'})
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
fixture 1{}{}Passed
fixture 2{'PORT': '0'}{'PORT': '0'}Passed
fixture 3{'PORT': ''}{'PORT': ''}Passed
fixture 4{'PORT': ''}{'PORT': ''}Passed
fixture 5{'PORT': 'missing'}{'PORT': 'missing'}Passed
fixture 6{'PORT': 'missing'}{}Failed
fixture 7{'PORT': '80'}{'PORT': '80'}Passed
fixture 8{'PORT': '80'}{'PORT': '80'}Passed

SHA-256 / 0883686c72745e7a38cf2d32271d438f987ea2930845e4b95d616b60cafc02c9

2 / The unsuccessful fix

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

N = 1
observations = []
def solve(declarations, environment, prefix):
    result = {}
    for name, default, required in declarations:
        key = prefix + name
        if key in environment: result[name] = environment[key]
        elif default is not None: result[name] = default
        elif not required: result[name] = 'missing'
    return result
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('fixture 1', solve([], {}, 'APP_'), {})
check('fixture 2', solve([('PORT', None, True)], {'APP_PORT': '0'}, 'APP_'), {'PORT': '0'})
check('fixture 3', solve([('PORT', '80', True)], {'APP_PORT': ''}, 'APP_'), {'PORT': ''})
check('fixture 4', solve([('PORT', '', True)], {}, 'APP_'), {'PORT': ''})
check('fixture 5', solve([('PORT', None, True)], {}, 'APP_'), {'PORT': 'missing'})
check('fixture 6', solve([('PORT', None, False)], {}, 'APP_'), {})
check('fixture 7', solve([('PORT', '80', False)], {}, 'APP_'), {'PORT': '80'})
check('fixture 8', solve([('PORT', '80', True)], {'PORT': '90'}, 'APP_'), {'PORT': '80'})
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
fixture 1{}{}Passed
fixture 2{'PORT': '0'}{'PORT': '0'}Passed
fixture 3{'PORT': ''}{'PORT': ''}Passed
fixture 4{'PORT': ''}{'PORT': ''}Passed
fixture 5{}{'PORT': 'missing'}Failed
fixture 6{'PORT': 'missing'}{}Failed
fixture 7{'PORT': '80'}{'PORT': '80'}Passed
fixture 8{'PORT': '80'}{'PORT': '80'}Passed

SHA-256 / 2532c03a994ec8ee69df5df5570ff2a7fc10258009669d30046fa7ad28bc5c32

3 / The verified repair

Exit 0
"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(declarations, environment, prefix):
    result = {}
    for name, default, required in declarations:
        key = prefix + name
        if key in environment: result[name] = environment[key]
        elif default is not None: result[name] = default
        elif required: result[name] = 'missing'
    return result
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('fixture 1', solve([], {}, 'APP_'), {})
check('fixture 2', solve([('PORT', None, True)], {'APP_PORT': '0'}, 'APP_'), {'PORT': '0'})
check('fixture 3', solve([('PORT', '80', True)], {'APP_PORT': ''}, 'APP_'), {'PORT': ''})
check('fixture 4', solve([('PORT', '', True)], {}, 'APP_'), {'PORT': ''})
check('fixture 5', solve([('PORT', None, True)], {}, 'APP_'), {'PORT': 'missing'})
check('fixture 6', solve([('PORT', None, False)], {}, 'APP_'), {})
check('fixture 7', solve([('PORT', '80', False)], {}, 'APP_'), {'PORT': '80'})
check('fixture 8', solve([('PORT', '80', True)], {'PORT': '90'}, 'APP_'), {'PORT': '80'})
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
fixture 1{}{}Passed
fixture 2{'PORT': '0'}{'PORT': '0'}Passed
fixture 3{'PORT': ''}{'PORT': ''}Passed
fixture 4{'PORT': ''}{'PORT': ''}Passed
fixture 5{'PORT': 'missing'}{'PORT': 'missing'}Passed
fixture 6{}{}Passed
fixture 7{'PORT': '80'}{'PORT': '80'}Passed
fixture 8{'PORT': '80'}{'PORT': '80'}Passed

SHA-256 / 49862693840bf82a6bde42dcd4a36b72a4730be0c206287b424f5c752a899d5e

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 2026-09-29T14:38:31.771218+00:00.

Case digest / 56d94a237083ee024b7dbdb76e01d1536119b59ecb65219119b270498f5fc733