Find the first step where an algorithm goes wrong.

FrontierLab gives algorithm libraries and AI agents semantic breakpoints, frame diffs, process contracts, first-divergence detection, and portable visual counterexamples.

Open Time-Travel Debugger →

Load the faulty AI-generated sort, run a semantic contract, jump to its first illegal mutation, and export the counterexample—all offline.

Insertion sort

Open the interactive comparison and swap trace.

Union-Find

Replay component merges and path compression.

A* frontier

Explore visits, relaxations, and the final path.

Generate the offline playground locally:

moon run cmd/main -- playground --output playground.html

Source and documentation · Gitlink mirror · Trace schema · Integration guide