Agent stack build plans · № 1

oh-my-pi as a Claude Code replacement

One evening to switch, one config file to route cheap models at cheap work and frontier models at the hard parts.

CLI: omp MIT · bring your own keys v17.0.9 · July 2026 19k GitHub stars

oh-my-pi is Can Bölük’s hard fork of pi, Mario Zechner’s open-source coding agent — rebuilt as a terminal-first Claude Code alternative: same shape (tools, MCP, sessions, skills, subagents, plan mode), plus the thing Claude Code doesn’t give you: you choose the model per kind of work. Frontier model for the gnarly refactor, a cheap or local model for commit messages and subagent fan-out, automatic fallback chains when a provider rate-limits you.

The cost story is the reason to care. It’s MIT-licensed and subscription-free: point it at API keys, log it into subscriptions you already pay for (Claude, Copilot, Cursor), or run free local models through Ollama — and mix all three in one session. The switch costs you an evening; on first run it even inherits your existing rules, skills, and MCP servers from .claude and friends, so your project config comes with you.

The plan, in five parts

1What you getthe routed-session demo — play with a week of agent work and watch where the money goes 2Set it upinstall, log in, migrate from Claude Code — real commands, ~20 minutes 3The routing configroles, models.yml, fallback chains, local models — the whole point, one file at a time 4The promptsstaged, paste-able — shake down the setup, then make omp tune its own config 5The trapsthe default is YOLO mode, arrays replace instead of append, and other surprises

Is this for you?

Yes, if you already live in a terminal agent and your API bill (or rate limit) is a monthly annoyance — routing is the fix, and nothing else ships it this complete. Yes, if you want local models in the loop for private repos. Skip it if Claude Code inside your existing subscription already covers you and cost isn’t a pressure: switching tools has a real attention price, and omp ships updates near-daily — you’re trading polish for control. This plan covers the switch and the routing config; it deliberately doesn’t tour all 32 tools, the extension API, or the Hermes-style always-on assistant category — that’s a different animal (and a different plan in this series).