Pi
Pi, the minimal coding agent and harness at https://pi.dev, written by mario-zechner, now owned by earendil since April 2026. Armin Ronacher’s description of it, “the minimal agent within OpenClaw” https://lucumr.pocoo.org/2026/1/31/pi/, is how it entered that ecosystem, and the site’s tagline is the design contract.
“There are many agent harnesses but this one is yours. Adapt Pi to your workflows, not the other way around.”
Sessions are JSONL trees with in-place branching (/tree, --fork), auto-compaction, model switching mid-session across a long provider list, and extension hooks; the README asks users to share coding-agent sessions as public OSS training-adjacent data via pi-share-hf https://github.com/earendil-works/pi.
Pi 1.0 shipped 2026-10-01 alongside Pi Durable, the experimental runtime for long-running agents: durable tasks with per-step checkpoints, replay-safe versus single-fire tools, exactly-once request ids, shared typed documents as application state, background compaction, handoff with history still searchable, live extension swaps, and detached agents reachable from terminals, browsers, HTTP, and co-workers at once https://earendil.com/posts/pi-durable/. See durable-agents, proactive-agents. The 1.0 release also added MCP support against the creator’s earlier position https://www.theregister.com/ai-and-ml/2026-10-02/pi-coding-agent-pulls-a-180-and-adds-mcp-support/5300678.
Two vault threads already ran through Pi without a page. Ryan’s Jev analysis session-history study (2026-09-20, the old vault) was computed over 136 pi sessions, and this repo’s .pi-subagents directory and AGENTS.md skills pipeline both invoke it. 2026-10-12-youtube-indydevdan-pi-durable is the first source page here, with the durable demos. The house rule for why any of this matters is the one IndyDevDan quotes without knowing he’s quoting the post: everything the harness runs is a task, which is what makes a near-the-loop posture survivable instead of aspirational. See harness-engineering.
Sources
- pi.dev: https://pi.dev/
- Earendil, Pi Durable, 2026-10-01: https://earendil.com/posts/pi-durable/
- repository: https://github.com/earendil-works/pi
- Armin Ronacher, “Pi: The Minimal Agent Within OpenClaw”, 2026-01-31: https://lucumr.pocoo.org/2026/1/31/pi/
- Mario Zechner, “What I learned building an opinionated and minimal coding agent”, 2025-11-30: https://mariozechner.at/posts/2025-11-30-pi-coding-agent