FA-24761 / Client state / Open access
Store writes notify a hydrating consumer before its server snapshot is released · case 01
Store writes notify a hydrating consumer before its server snapshot is released.
ROOT CAUSE
The faulty implementation violates Before hydration release a consumer queues store snapshots; release delivers only the latest held snapshot, and subsequent writes deliver in order. Repeated release is idempotent.
VERIFIED REPAIR
Before hydration release a consumer queues store snapshots; release delivers only the latest held snapshot, and subsequent writes deliver in order. Repeated release is idempotent.
Unsuccessful approach: The partial repair still violates at least one explicit regression oracle.
Case contract
Before hydration release a consumer queues store snapshots; release delivers only the latest held snapshot, and subsequent writes deliver in order. Repeated release is idempotent.
Why this case matters
A bounded offline client-state transition with explicit lifecycle inputs.
1 / The failure
Exit 1"""Failure Map reference implementation. Python standard library only."""
import json
N = 1
observations = []
def solve(events):
return [v for kind,v in events if kind=='write'],[]
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('coalesce prehydrate writes', solve([('write',1),('write',2),('hydrate',None)]), ([2],[]))
check('still hydrating', solve([('write',N)]), ([],[N]))
check('writes after release', solve([('hydrate',None),('write',N)]), ([N],[]))
check('no writes', solve([('hydrate',None)]), ([],[]))
check('repeat hydration no duplicate', solve([('write',0),('hydrate',None),('hydrate',None)]), ([0],[]))
check('posthydrate ordering', solve([('write',1),('write',2),('hydrate',None),('write',3)]), ([2,3],[]))
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 |
|---|---|---|---|
| coalesce prehydrate writes | [[1, 2], []] | [[2], []] | Failed |
| still hydrating | [[1], []] | [[], [1]] | Failed |
| writes after release | [[1], []] | [[1], []] | Passed |
| no writes | [[], []] | [[], []] | Passed |
| repeat hydration no duplicate | [[0], []] | [[0], []] | Passed |
| posthydrate ordering | [[1, 2, 3], []] | [[2, 3], []] | Failed |
SHA-256 / 6fffa81bffff130c408c86353cda7f5d4a64a93f8629f195dba28fcf653aebaa
2 / The unsuccessful fix
Exit 1"""Failure Map reference implementation. Python standard library only."""
import json
N = 1
observations = []
def solve(events):
hydrating=True; held=[]; delivered=[]
for kind,value in events:
if kind=='write':
if hydrating: held.append(value)
else: delivered.append(value)
elif kind=='hydrate':
hydrating=False; delivered+=held; held=[]
return delivered,held
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('coalesce prehydrate writes', solve([('write',1),('write',2),('hydrate',None)]), ([2],[]))
check('still hydrating', solve([('write',N)]), ([],[N]))
check('writes after release', solve([('hydrate',None),('write',N)]), ([N],[]))
check('no writes', solve([('hydrate',None)]), ([],[]))
check('repeat hydration no duplicate', solve([('write',0),('hydrate',None),('hydrate',None)]), ([0],[]))
check('posthydrate ordering', solve([('write',1),('write',2),('hydrate',None),('write',3)]), ([2,3],[]))
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 |
|---|---|---|---|
| coalesce prehydrate writes | [[1, 2], []] | [[2], []] | Failed |
| still hydrating | [[], [1]] | [[], [1]] | Passed |
| writes after release | [[1], []] | [[1], []] | Passed |
| no writes | [[], []] | [[], []] | Passed |
| repeat hydration no duplicate | [[0], []] | [[0], []] | Passed |
| posthydrate ordering | [[1, 2, 3], []] | [[2, 3], []] | Failed |
SHA-256 / 5c91de4458392667c54a4489bb4b8598b0722ef53efc63ce8a1941c6f41070ba
3 / The verified repair
Exit 0"""Failure Map reference implementation. Python standard library only."""
import json
N = 1
observations = []
def solve(events):
hydrating=True; held=[]; delivered=[]
for kind,value in events:
if kind=='write':
if hydrating: held.append(value)
else: delivered.append(value)
elif kind=='hydrate':
hydrating=False
if held: delivered.append(held[-1]); held=[]
return delivered,held
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('coalesce prehydrate writes', solve([('write',1),('write',2),('hydrate',None)]), ([2],[]))
check('still hydrating', solve([('write',N)]), ([],[N]))
check('writes after release', solve([('hydrate',None),('write',N)]), ([N],[]))
check('no writes', solve([('hydrate',None)]), ([],[]))
check('repeat hydration no duplicate', solve([('write',0),('hydrate',None),('hydrate',None)]), ([0],[]))
check('posthydrate ordering', solve([('write',1),('write',2),('hydrate',None),('write',3)]), ([2,3],[]))
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 |
|---|---|---|---|
| coalesce prehydrate writes | [[2], []] | [[2], []] | Passed |
| still hydrating | [[], [1]] | [[], [1]] | Passed |
| writes after release | [[1], []] | [[1], []] | Passed |
| no writes | [[], []] | [[], []] | Passed |
| repeat hydration no duplicate | [[0], []] | [[0], []] | Passed |
| posthydrate ordering | [[2, 3], []] | [[2, 3], []] | Passed |
SHA-256 / f72feae216b1f5fd566e7f57e53c0ef3f1124f1f3d334aae18dcd623843f3314
Verification & scope
This models the stated application policy only; no browser or framework conformance is claimed. 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 2026-09-29T14:41:00.575399+00:00.
Case digest / b48776a964eef380333ed57c7285b6d0d43af0c2ced7ec777731da2fd8e47904