Change the wording, keep your experiment. Saved in this browser when storage is available.
Why do two agents overwrite each other's work?
Keep both helpers’ edits in your flight poster
Two helpers start from the same poster. One adds stars; the other changes the words. Saving an old whole copy can erase the other helper’s work. Try the saves, then turn on the version check to catch an old copy before it overwrites anything.One adds a starry sky. One changes the lettering. Save their copies and see which work survives. Then require a version check: you will see why two AI helpers editing the same document need to detect an old copy before saving it.
Local simulation with two editable helper copies. No live AI, accounts or requests.
The shared poster
Version 1Night flight. Dusk sky. No stars.
Editable vector artwork. The download matches the saved version you are viewing.
Start with the two prepared drafts. Save the illustration, then the lettering. Or reverse the order.
Illustration helper
Prepared from version 1
Prepared edit: midnight sky with stars.
Edit or re-read copy A
Re-reading replaces this draft. Compare first to keep its changes.
Lettering helper
Prepared from version 1
Prepared edit: “Follow the stars” lettering.
Edit or re-read copy B
Re-reading replaces this draft. Compare first to keep its changes.
Enable JavaScript to control the two copies. The worked example below remains available.
A detected conflict still needs a decision
Choose what the merged poster keeps
Someone could save again while you choose what to keep. So the final combined save checks the version again, even when ordinary saves use replace mode.A new save can make this comparison stale too. The merged save always checks its version, even in replace mode.
Inspect the versions you actually made
Choose a saved version to view it. Viewing history does not restore or overwrite the shared poster.
Action order and reproducible downloads
The list records your reads, edits and saves in order. This simulated schedule runs on one device; it does not measure a distributed system.
Changes live in this tab. Save or update your drafts before keeping the history. You can restore that file below after leaving or reloading.
Local file only, up to 128 KB. We replay its actions and check the result before replacing this session. Undo can recover the session you replaced.
Worked example: lose an edit, then protect it
- Save illustration A, then lettering B in replace mode. B saves its whole old copy. The new sky and stars disappear.
- Choose “Try again with version checks.” Save A, then B. B's save is held because its version is old. The shared poster stays intact.
- Compare B with shared. Review the lettering from B and the sky and stars from shared. Save the combination.
- For a harder case, edit the title in both copies before saving. The comparison cannot pick the correct title for you.
The mechanism is old; AI does not invent version checking. It matters when AI helpers edit shared work through tools. This scene lets you control the scheduling and semantic choices directly.
What if the comparison itself goes stale?
You compare a helper’s draft against version 5. Before you save the merge, another helper saves version 6. Which action protects that new work?
Choose the check that still needs to happen.
Optional: a correction that arrives a day late
What did the helpers know at the time?
The flight was listed at 19:00. It changed to 20:00 on October 11, but the helpers received that correction on October 12. These are authored records, not automatically discovered facts.
“When did it change?” and “When did we hear about it?” can have different answers. This query shows what the records say; it does not prove what happened outside them.The effective date and the received date answer different questions. This query describes the stored account, not proof of what happened in the world.
Mechanism, sources and credits
The illustration and both helpers use original fixed local rules. Jonathan Simone directs Simone Systems Research as an independent developer, with AI assistance in implementation and review. These helpers are not independent language models and do not generate new artwork.
The conditional-save model follows the idea explained in MDN’s lost-update example. A stale expected version is rejected. This is not a database implementation or a claim of transaction isolation; see PostgreSQL’s isolation documentation for broader guarantees.
Interaction research: Bret Victor’s controllable time and concrete states and Learn Git Branching’s visible history. No code or artwork copied. You may download and edit this original teaching artwork for personal use.
Design estimate: 5–10 minutes plus optional exploration. Human enjoyment and learning have not been tested. Version checks protect against this specific stale-copy write; they do not establish general AI memory, correctness or safe collaboration.