Say what should survive.
Start with a specific expectation. Our first example names a decision and an unfinished task before the test begins.
What carries
forward?
Save a decision and a task.
Check what survives restoration.
For developers and admins building software that saves and restores state.
ReplayProof is now available in the Microsoft Store for Windows. Compare selected saved facts and responses before and after restoration in its bundled assistant workflow. Start offline, or connect your own Gemini access or a compatible local model server.
Available in the Microsoft Store · First release October 14, 2026
ONE CLIENT. TWO THINGS TO RETAIN.
N
Northstar Studio
Fictional client · Before checkpoint
01 / AGREED DECISION
Prepare a one-page
launch plan.
Confirm the launch budget.
Save & restore
RETURN TO THE CLIENT
“What did we decide,
and what’s still to do?”
Compare the answer. Inspect the state.
An illustrative starting example. In the Windows app, enter your own non-sensitive decision and task.
FROM A PROMISE TO A CHECK
A clear question.
An inspectable answer.
Cross a defined boundary.
Save the fictional state, restore it into a fresh instance, then give a reference instance and the restored instance the same follow-up questions.
See what the result means.
Inspect matching and missing values. Every verdict comes with the checks, the boundary, and what remains unanswered.
THE DATA. THE RULES. THE EVIDENCE.
What gets checked?
The Windows app checks a decision and a task across checkpoint and restore within one running process. Saved data and responses are checked separately. You confirm the expected facts before the run.
| Selected value | 01 / ORIGINALBefore saving | 02 / RESTOREDAfter restore |
|---|---|---|
| Decision | Prepare a one-page launch plan. | Prepare a one-page launch plan.Retained |
| Task | Confirm the launch budget. | Missingnull |
03 / COMPARE
The task-state comparison fails. The original task and restored value do not match. The follow-up answer is checked separately.
The report shows expected and actual values for every check. Comparisons follow predefined rules; an AI does not judge whether answers seem equivalent.
Technical details: checkpoints, comparison rules & SHA-256
Checkpoint and contract. An adapter supplies the checkpoint and observable values; a test contract specifies which values to compare and which rules to use. The current workflow checks a decision and task. Live connections restore the bundled assistant checkpoint into a fresh graph and separate in-memory store in the same process. They do not restore model internals or an existing provider chat.
Comparison stages. The app checks selected state values before and immediately after restoration. It gives a reference instance and the restored instance the same follow-up questions, then compares their answers and final state.
Exact comparison. The verifier converts JSON values into a consistent representation, sorting object keys before comparing. Compared text must match exactly; array order is preserved. Live model checks extract the requested fact from the response; the accompanying explanation is not scored.
SHA-256 fingerprints. The evidence records hashes of the test contract, adapter code, setup and continuation input files, and serialized checkpoint. These identify the materials used in a run. File hashes use the file contents; the checkpoint hash uses its canonical JSON representation.
The comparison rules determine whether the declared checks pass. Hashes alone do not establish correct behavior after restoration. In the app, the report retains the compared values so you can inspect each match or mismatch.
THREE WAYS TO EXPLORE
Start offline.
Bring a model when ready.
Example test
Use the offline simulator with scripted responses. No account, API key or model download is needed. Explore complete restoration, deliberate task loss, unavailable observation and unsupported comparison.
Online API · Gemini
Connect your own Gemini API key. After your confirmation, the app sends selected test state and questions to Google. Google’s terms and charges apply; API access is not included.
Local API · Your model
Connect an already running LM Studio-compatible server on this computer and enter its exact model ID. Models and server software are not included. API compatibility alone does not qualify every model.
Live runs use at most four requests with no automatic retries. Use fictional or non-sensitive text. Local servers may log or forward requests. Read about data handling.
RUN. COMPARE. INSPECT.
See what matched.
Understand what did not.
Enter a decision and unfinished task, confirm your expectations, and choose a restore condition. The Windows app shows expected and actual values and can save a JSON evidence report. A deliberately lost task is a useful failure control.
Preview the Windows screensExplore the Windows interface here, then get ReplayProof from the Microsoft Store to run your own checks. This website does not run checks or produce results.
All declared checks passed in this run.
A required comparison did not match.
This setup cannot perform the requested check.
The available evidence could not establish a verdict.
CONFIDENCE WITH CONTEXT
A result should tell you its limits.
What the current workflow covers
Selected facts across checkpoint and restore in the bundled workflow, within one running process. Inspect state comparisons separately from scripted or model responses. A pass applies only to the declared checks in that run.
What it does not establish
Restoration of existing ChatGPT, Claude, Gemini or other chat sessions; application restart; crash recovery; storage durability; general model quality; or production reliability. A passing check does not prove a system will always remember.
ReplayProof is available in the Microsoft Store. See the listing for current pricing and availability in your region. Requirements and support.
HELP SHAPE WHAT COMES NEXT
What needs to carry forward
in your work?
Our first release is here. Tell us what your software saves, what sometimes goes missing, and how you check it today. Your feedback will help shape what comes next.
Email ReplayProofOpens your email app. You can also write directly to ReplayProof@gmail.com.
Who’s behind ReplayProof?
ReplayProof is being developed by James Primeau in Jacksonville, Florida.
Contact & privacy
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