REPL.io

A lightweight agentic tooling core with API, CLI and REPL interfaces.

REPL.io is deliberately small and auditable zero-dependency agentic core built on a single streaming agent loop. The model plans, the tool registry acts, and one loop serves three front-ends: an interactive REPL, a headless one-shot CLI, and an HTTP API.

Why

• Zero dependencies — everything is Python standard library. No dependency tree to audit, no supply-chain surface, no lockfile churn
• One agent loop — a single SSE stream per turn powers the REPL, the CLI, and the API. No duplicated logic across front-ends
• Local-first — config and session logs live on your disk. Bring your own provider key, or run fully local

Features

• Agentic REPL — streaming token-by-token output, dimmed thinking, markdown-aware rendering, readline history and tab completion
• Tool calling — web search, page fetching, file read/write/search, and shell execution via OpenAI-compatible function calling
• Permissions — every tool is gated by allow / ask / deny, with path-scoped confirmations for anything outside your worktree
• Plugins — external repositories register tools, providers, and slash commands; the core stays zero-dependency and plugin deps are imported lazily, only when you activate a plugin
• Multi-provider — Ollama, OpenAI, Groq, Anthropic, plus any OpenAI-compatible endpoint, with automatic detection from the base URL
• Sessions — complete append-only conversation logs, including every tool call and its result
• Compaction — summarize long conversations and trim the provider context without losing history
• Headless modes — replio run for scripting and replio serve for an HTTP JSON API

Quick Start

pipx install replio
replio

Or from source:

git clone https://github.com/emyasnikov/replio.git && cd replio
python3 -m venv .venv && .venv/bin/pip install -e .
.venv/bin/replio

Usage

REPL

First-time setup with /connect, then type any message. Tab-complete / commands and session names. Use arrow keys to navigate history.

>>> /connect
  Provider [ollama]:
  Base URL [https://ollama.com]:
  API key: ...
  Model [gpt-oss:20b-cloud]:
>>> Hi
<<< Hello! How can I help you today?
>>> /exit

CLI

Stream plain text with --output text or return the results as JSON, log tool status and diagnostics to stderr with --verbose, and address a persistent session with --session-id <id>. Tools that require confirmation are auto-denied in by default, just pass --yes to approve them.

replio run --prompt "Hi"
{
  "content": "Hello! How can I help you today?",
  "thinking": null,
  "tool_calls": [],
  "errors": [],
  "duration": 7.0,
  "usage": null,
  "model": "gpt-oss:20b-cloud",
  "provider": "ollama",
  "session": "20260814_192251_hi",
  "status": "ok"
}

API

Server exposes different JSON endpoints like POST /chat ({"prompt": ...}, optionally {"session_id": ...}) returns the same turn result as the CLI etc.

replio serve &
curl localhost:8787/chat -X POST -d '{"prompt": "Hi"}'
{"content": "Hello! 👋 How can I help you today?", "thinking": null, "tool_calls": [], "errors": [], "duration": 7.0, "usage": null, "model": "gpt-oss:20b-cloud", "provider": "ollama", "session": "20260814_192711_hi", "status": "ok"}

Roadmap

Personas and delegation are planned next. The plugin system is in place (web and machine tools now ship as bundled plugins), and third-party plugins install from git or a path. See docs/plugins.md. Open tasks live in TODO.md.

Contributing

The project is stdlib-only with no external dependencies. See AGENTS.md for architecture and conventions, and CONTRIBUTING.md for the contribution workflow.

Documentation

Detailed references are in the docs:

• API endpoints
• Configuration
• Commands & CLI
• Plugins

License

MIT