Phoson: A Framework-Free Minimal Open-Source Agent Runtime With Terminal CLI

abelsr_1710 · reddit · 2026-09-25

Developer abelsr1710 released Phoson, an MIT-licensed, framework-free Python runtime for AI agents with a terminal-first CLI.

The thesis: agent frameworks often become more complicated than the agents themselves, so Phoson keeps the harness small, understandable, and replaceable — no LangChain, no LangGraph, no huge abstraction layer.

Features include a ReAct-style agent loop, multiple LLM providers behind one interface, tools + MCP, typed streaming events, branchable/resumable sessions, token/cost tracking, and plugins. The CLI lets you start sessions from the terminal, switch providers/models, attach tools or MCP servers, and resume past sessions. The author says the goal isn't another coding-assistant clone but the runtime layer between an LLM and the real world.

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