crossjam/mpr

--- title: "pi coding agent" date: 2026-01-03 13:30 author: "C. Ross Jam" status: published ---

Thanks to Armin Ronacher, I learned about the [pi coding agent][1]. Mario Zechner’s blog post on [what he learned building pi][2] outlines his underlying principles in creating an agentic coding framework:

In the past three years, I've been using LLMs for assisted coding. If you read this, you probably went through the same evolution: from copying and pasting code into ChatGPT, to Copilot auto-completions (which never worked for me), to Cursor, and finally the new breed of coding agent harnesses like Claude Code, Codex, Amp, Droid, and opencode that became our daily drivers in 2025. ... So what's an old guy yelling at Claudes going to do? He's going to write his own coding agent harness and give it a name that's entirely un-Google-able, so there will never be any users. Which means there will also never be any issues on the GitHub issue tracker. How hard can it be? To make this work, I needed to build: - [pi-ai][3]: A unified LLM API with multi-provider support (Anthropic, OpenAI, Google, xAI, Groq, Cerebras, OpenRouter, and any OpenAI-compatible endpoint), streaming, tool calling with TypeBox schemas, thinking/reasoning support, seamless cross-provider context handoffs, and token and cost tracking. - [pi-agent-core][4]: An agent loop that handles tool execution, validation, and event streaming. - [pi-tui][5]: A minimal terminal UI framework with differential rendering, synchronized output for (almost) flicker-free updates, and components like editors with autocomplete and markdown rendering. - [pi-coding-agent][6]: The actual CLI that wires it all together with session management, custom tools, themes, and project context files. My philosophy in all of this was: if I don't need it, it won't be built. And I don't need a lot of things.