FA-1316 / Workflow orchestration / Open access

Release a workflow dependency join: Duplicate predecessor events release the join twice · case 01

The workflow join operation is admitted even though duplicate predecessor events release the join twice.

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

ROOT CAUSE

The admission path omits the release once invariant while validating the other operation preconditions.

THE FAILURE

The admission path omits the release once invariant while validating the other operation preconditions.

Unsuccessful approach: Adding the release once check repairs the reported defect, but replacing the adjacent cancelled branch check loses that independent invariant.

Case contract

Return a Boolean admission decision for release a workflow dependency join. The record r must satisfy all of: set(r['all_required'][0]) <= set(r['all_required'][1]); all(x == 'success' for x in r['success_policy']); all(x == r['branch_generation'][0] for x in r['branch_generation'][1]); r['release_once'] is False; not any(r['cancelled_branch']). Extra tracing fields are ignored; validation does not mutate the record.

Why this case matters

A deterministic local contract for workflow orchestration. Each negative fixture violates exactly one invariant. No transport timing, persistence, cryptographic verification, or full protocol implementation is claimed.

1 / The failure

Exit 1

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

N = 1
observations = []
def solve(r):
    return (set(r['all_required'][0]) <= set(r['all_required'][1])) and (all(x == 'success' for x in r['success_policy'])) and (all(x == r['branch_generation'][0] for x in r['branch_generation'][1])) and (not any(r['cancelled_branch']))
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
r = {'all_required': [['a', 'b'], ['a', 'b']], 'success_policy': ['success', 'success'], 'branch_generation': [3, [3, 3]], 'release_once': False, 'cancelled_branch': [False, False]}
check('valid operation', solve(r), True)
check('A join proceeds before every required predecessor completes', solve(dict(r, **{'all_required': [['a', 'b'], ['a']]})), False)
check('A success-only join treats failed predecessors as successful', solve(dict(r, **{'success_policy': ['success', 'failed']})), False)
check('A completion from a previous loop iteration satisfies the join', solve(dict(r, **{'branch_generation': [3, [2, 3]]})), False)
check('Duplicate predecessor events release the join twice', solve(dict(r, **{'release_once': True})), False)
check('A cancelled required branch is silently omitted', solve(dict(r, **{'cancelled_branch': [False, True]})), False)
check('unrelated tracing metadata', solve(dict(r, trace='run-'+str(N))), True)
check('repeat validation is pure', solve(r), True)
invalid = {'all_required': [['a', 'b'], ['a']], 'success_policy': ['success', 'failed'], 'branch_generation': [3, [2, 3]], 'release_once': True, 'cancelled_branch': [False, True]}
keys = list(invalid)
pair = {keys[N % len(keys)]: invalid[keys[N % len(keys)]], keys[(N+1) % len(keys)]: invalid[keys[(N+1) % len(keys)]]}
check('two independent violations in variant', solve(dict(r, **pair)), False)
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
valid operation	`True`	`True`	Passed
A join proceeds before every required predecessor completes	`False`	`False`	Passed
A success-only join treats failed predecessors as successful	`False`	`False`	Passed
A completion from a previous loop iteration satisfies the join	`False`	`False`	Passed
Duplicate predecessor events release the join twice	`True`	`False`	Failed
A cancelled required branch is silently omitted	`False`	`False`	Passed
unrelated tracing metadata	`True`	`True`	Passed
repeat validation is pure	`True`	`True`	Passed
two independent violations in variant	`False`	`False`	Passed

SHA-256 / d3ad882777567fc850a8b6cb756742966f338504fa118535514c93e313a269ba

2 / The unsuccessful fix

Exit 1

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

N = 1
observations = []
def solve(r):
    return (set(r['all_required'][0]) <= set(r['all_required'][1])) and (all(x == 'success' for x in r['success_policy'])) and (all(x == r['branch_generation'][0] for x in r['branch_generation'][1])) and (r['release_once'] is False)
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
r = {'all_required': [['a', 'b'], ['a', 'b']], 'success_policy': ['success', 'success'], 'branch_generation': [3, [3, 3]], 'release_once': False, 'cancelled_branch': [False, False]}
check('valid operation', solve(r), True)
check('A join proceeds before every required predecessor completes', solve(dict(r, **{'all_required': [['a', 'b'], ['a']]})), False)
check('A success-only join treats failed predecessors as successful', solve(dict(r, **{'success_policy': ['success', 'failed']})), False)
check('A completion from a previous loop iteration satisfies the join', solve(dict(r, **{'branch_generation': [3, [2, 3]]})), False)
check('Duplicate predecessor events release the join twice', solve(dict(r, **{'release_once': True})), False)
check('A cancelled required branch is silently omitted', solve(dict(r, **{'cancelled_branch': [False, True]})), False)
check('unrelated tracing metadata', solve(dict(r, trace='run-'+str(N))), True)
check('repeat validation is pure', solve(r), True)
invalid = {'all_required': [['a', 'b'], ['a']], 'success_policy': ['success', 'failed'], 'branch_generation': [3, [2, 3]], 'release_once': True, 'cancelled_branch': [False, True]}
keys = list(invalid)
pair = {keys[N % len(keys)]: invalid[keys[N % len(keys)]], keys[(N+1) % len(keys)]: invalid[keys[(N+1) % len(keys)]]}
check('two independent violations in variant', solve(dict(r, **pair)), False)
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
valid operation	`True`	`True`	Passed
A join proceeds before every required predecessor completes	`False`	`False`	Passed
A success-only join treats failed predecessors as successful	`False`	`False`	Passed
A completion from a previous loop iteration satisfies the join	`False`	`False`	Passed
Duplicate predecessor events release the join twice	`False`	`False`	Passed
A cancelled required branch is silently omitted	`True`	`False`	Failed
unrelated tracing metadata	`True`	`True`	Passed
repeat validation is pure	`True`	`True`	Passed
two independent violations in variant	`False`	`False`	Passed

SHA-256 / 1e83c106a6ea97150a7a40ef56337a68080802ed7989f8cdedc736ebfb5fb976

HELD IN THE MEMBER ARCHIVE

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

This mechanism has 9 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

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 2026-09-29T14:37:00.957343+00:00.

Case digest / 1dd88c59329ec35e93c7786f68e6849924008f9c1c6132c0e8689cafcadf33b3