AI Lab Β· Free tool
HCS live: the context that knows when it goes wrong
A context file for AI goes stale as soon as the code changes. Edit the example project and watch the HCS engine spot, without any AI, what is stale or moved. Or check your own project: everything stays in your browser.
π Everything is computed in your browser: nothing is sent to or stored on a server.
The official HCS example project: a small shop (TypeScript and Python code, rules in Markdown) and its context file of 41 claims and 12 test questions, each tied to its source by a hash. Edit the code: the real HCS engine re-checks everything at every keystroke.
Try a scenario in one click
Project files
Edit this file freely: the result updates by itself.
What the HCS engine checks
- Loading the HCS engineβ¦
What an AI would receive
The context rendered in the compact profile (like `hcs render` and the MCP server): stale claims are left out, and the budget limits the size.
`hcs check` report
Already using HCS? Check your project without installing anything: choose the folder that holds your code and your .hcs file. Everything is read and checked in this browser, nothing is uploaded. No AI is used: only the deterministic check runs here.
or drag and drop the folder here
Limits: 5,000 files and 20 MB in total; node_modules, .git and binary files are skipped.
π Your code never leaves your device: no server, no account, no tracker.
`hcs check` report
Going further
Creating a .hcs file (with the AI of your choice, even a local one), measuring it and serving it to an agent over MCP: that is the command-line tool.
The HCS project page Install: npm install -g @oufrid/hcs-cli The code on GitHub
Why this tool
The problem, visible live
CLAUDE.md, AGENTS.md, project summaries: nothing warns you when the code changes. Here every claim carries the hash of its source: change a price and it turns red at once.
The real engine, no AI
The published HCS code (version 0.3.0) runs in the page and gives exactly the same results as the hcs check command. Checking is computation: no AI, no key, no cost.
Your project stays with you
The "Check my project" tab reads your folder in the browser and shows the hcs check report. Nothing is uploaded.
Frequently asked questions
Do I need an API key or an AI to use this tool?
No. Checking, following moved code and rendering the context are deterministic computations. Only creating a .hcs file automatically and measuring fidelity need an AI, and they are done with the command-line tool and the model of your choice.
Why does a simple reformat break nothing?
For functions and classes, HCS hashes the code with all whitespace removed: changing indentation or layout leaves the hash unchanged. A change in the logic changes it.
What does "moved" mean?
The cited code did not change but is no longer in the same place: other lines, or another file for a function. HCS finds it again by its hash, and the hcs seal command updates the anchor.
Is my code sent anywhere?
No. The files are read by your browser and checked on the spot. Closing the tab erases everything.
Going further
Your AI context files lie silently: I built HCS to measure it
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