Skip to content
Multi user bug detection

Catch the bug only two users can make.

Collision Canary drives two real browsers at the exact same moment, then proves whether your app keeps its promise: only one person can grab the last seat.

Alice
books the seat
Claim
Final seat
1
1 left
Bob
books the seat
Claim

Both click at once. Only one should win.

Runs onKaneNeonVercelCodex

Your tests pass. Your users still collide.

Single user tests never see it. The failure only shows up when two people act on the same thing at the same instant, and one shared record says yes to both.

one seattwo winners
Alicewon
Bobwon

One seat, two winners. That is the bug.

Four steps, two real browsers.

1

Arm

Two live browsers open the same action and wait.

2

Release

Both fire at the exact same moment.

3

Check

We test the promise against the real database.

4

Repair

A fix packet goes to your coding agent, then re-run.

No simulations
Real browsers

Actual Chrome sessions, driven by Kane, not scripted mocks.

One source of truth
Real database

A shared Neon Postgres row and a real transaction decide the winner.

When it breaks
A fix packet

A redacted, hashed task your agent can act on. Then prove the fix.

The last seat is everywhere.

The final airplane seat. The last concert ticket. One promo code left. Each one is a race two users can break at the same instant. Collision Canary makes that race visible and proves who really wins.

A single empty seat beside an airplane window
Photo: Rudy Dong on Unsplash

Every run is a real record.

No screenshots, no promises. This is the most recent proof, straight from the database.

run_492BVerified
Winners
1
Seats left
0
See the full proof

See it collide, then watch it get fixed.

Run the last-seat test on a live app in under a minute.