Good project for understanding coding agents?

[Cabanas]

I’ve been using terminal coding agents for a while, but most of the time they still feel like a black box. I’d like to dig into an open-source implementation and see how things like the agent loop, tool calls, permissions and session state actually fit together instead of just reading high-level articles about them. Ideally the codebase would be small enough to follow without spending weeks figuring out the architecture first. Are there any good projects to study if I want to understand how tools like Claude Code work internally?

[Picasso]

A huge codebase can make this harder because you end up learning the project itself before you really understand the agent behavior. I’d start with something where the loop is short enough that you can trace one request from the prompt through tool execution and back into the next model call. mini-swe-agent is worth looking at for that. It keeps the core pretty compact, so you can actually follow how the agent decides what to do, runs commands, and continues from the result.

[Bermudo]

Another useful approach is to study a project that stays close to the terminal coding workflow you already know. That makes it easier to connect the code you’re reading with the behavior you see when using tools like Claude Code. You can take a look here: https://github.com/projectbarks/gopher-code . The repository is small enough to trace the main flow without getting buried in layers of infrastructure. It’s a good place to follow how the agent loop, tools, permissions, and session state are wired together in practice.