Code Instances on CodeInstances.com

The CodeInstances File Format Is Open JSON With a SHA-256 ID

Sun, 18 Oct 2026 00:00:00 +0000

The file is the product. A tool can be replaced, but a run you kept in a format only one tool reads is a run you’ll lose eventually. So the instance format is open JSON, written down in full in FORMAT.md for anyone who wants to read or write instances with their own tools.

Its name is codeinstances/0, and that string is the first member of every file. A reader that sees a format version it doesn’t know has to refuse the file, and readers ignore members they don’t recognise. A file that holds the same member twice, or a known member spelled in another case, is refused. That’s how the format can grow without breaking files that already exist.

What a Code Instance Is and Why Program Runs Should Be Kept Like Code

Sun, 18 Oct 2026 00:00:00 +0000

If you’ve written object-oriented code, you already know the idea. A class is a blueprint. Each object you make from it is an instance of that class, with its own state. One Order class, thousands of orders.

Your program works the same way. The code is the blueprint, and every time it runs, that run is an instance of it. Same code, different day, different answers from the servers it talks to, different clock, different random numbers. Each run is its own thing.

Why Replay Matters for AI Agents That Take a Different Path Every Run

Sun, 18 Oct 2026 00:00:00 +0000

Most programs are boring in a good way. Give them the same input and they do the same thing. If one fails, you can usually run it again and watch it fail again.

An AI agent isn’t like that. The model’s answer varies from run to run, so the agent picks different tools, calls them in a different order, reads different pages and ends somewhere else. Ask it the same thing three times and you may get three different runs, and only one of them may go wrong. Run it again to see what happened, and you’re watching a different run.

Why the Project Is Called CodeInstances

Sun, 18 Oct 2026 00:00:00 +0000

The name is the idea, in two words. Code is the program you write. An instance is one run of it.

Programmers already use “instance” this way. An object is an instance of its class. A server is an instance of an image. A running process is an instance of a program. In each case there’s one blueprint and many concrete things made from it, each with a life of its own. A run of your code fits right in. It’s made from the code, but it also has things the code doesn’t: the answers it got from the network that day, the time on the clock, the random numbers it drew.