alt Hacker NewsSeems everyone is working on the same things these days. I built a persistent Python REPL subprocess as an MCP tool for CC, it worked so insanely well that I decided to go all the way. I already had an agentic framework built around tool calling (agentlib), so I adapted it for this new paradigm and code agent was born.
The agent "boots up" inside the REPL. Here's the beginning of the system prompt:
>>> help(assistant)
You are an interactive coding assistant operating within a Python REPL.
Your responses ARE Python code—no markdown blocks, no prose preamble.
The code you write is executed directly.
>>> how_this_works()
1. You write Python code as your response
2. The code executes in a persistent REPL environment
3. Output is shown back to you IN YOUR NEXT TURN
4. Call `respond(text)` ...
I also built a browser control plugin that puts Claude directly into the heart of a live browser session. It can inject element pickers so I can click around and show it what I'm talking about. It can render prototype code before committing to disk, killing the annoying build-fix loop. I can even SSH in from my phone and use TTS instead of typing, surprisingly great for frontend design work. Knocked out a website for my father-in-law's law firm (gresksingleton.com) in a few hours that would've taken 10X that a couple years ago, and it was super fun.
The big win: complexity. CC has been a disaster on my bookkeeping system, there's a threshold past which Claude loses the forest for the trees and makes the same mistakes over and over. Code agent pushes that bar out significantly. Claude can build new tools on the fly when it needs them. Gemini works great too (larger context).
Have fun out there! /end-rant
Replies
This sounds really cool! I love the idea behind it, the agent having persistent access to a repl session, as I like repl-based workflows in general. Do you have any code public from this by any chance?
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> there's a threshold past which Claude loses the forest for the trees and makes the same mistakes over and over.
Try using something like Beads with Claude Code. Also don't forget to have a .claude/instructions.md file, you can literally ask Claude to make it for you, this is the file Claude reads every time you make a new prompt. If Claude starts acting "off" you tell it to reread it again. With Beads though, I basically tell Claude to always use it when I pitch anything, and to always test that things build after it thinks its done, and to ask me to confirm before closing a task (They're called beads but Claude figures what I mean).
With Beads the key thing I do though once all that stuff is setup is I give it my ideas, it makes a simple ticket or tickets. Then I both braindump and / or ask it to do market research on each item and the parameters I want to be considered, and then to update the task accordingly. I then review them all. Then I can go "work on these in parallel" and it spins up as many agents as there are tasks, and goes to work. I don't always make it do the work in parallel if its a lot of tasks because Zed has frozen up on me, I read that Claude Code is fine its just the protocol that Zed uses that gets hosed up.
I find that with Beads, because I refine the tickets with Claude, it does way better at tasks this way. It's like if you're hand crafting the "perfect" prompt, but the AI model is writing it, so it will know exactly what you mean because it wrote it in its own verbiage.