octo-agent

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A functionality-first AI agent, distributed as a single Go binary. Speaks two native API protocols — Anthropic Messages and OpenAI Chat Completions — and works against any compatible third party (DeepSeek, Kimi, Bailian, OpenRouter, vLLM, …). Aims for three equal interfaces: CLI, Web, and IM.

Status

Pre-1.0. CLI is functional today; Web UI and IM bridges land in later milestones — see dev-docs/go-rewrite-roadmap.md.

Install

Until tagged releases ship, build from source:

git clone https://github.com/Leihb/octo-agent.git
cd octo-agent
make build       # produces ./octo

Or install directly from Go:

go install github.com/Leihb/octo-agent/cmd/octo@latest

Quick start

export ANTHROPIC_API_KEY=sk-ant-...      # or OPENAI_API_KEY=...

# Single-shot
octo chat "Explain ring buffers in 100 words"

# Interactive REPL (multi-turn, session auto-saved)
octo chat

# Resume a previous session
octo chat --list-sessions
octo chat -c <session-id>

# Streaming on by default; turn off with --stream=false
octo chat --stream=false "..."

# OpenAI / DeepSeek / Bailian (OpenAI-compatible)
octo chat --provider openai --model gpt-4o-mini "..."

# Anthropic-compatible third parties (DeepSeek, Kimi, etc.)
ANTHROPIC_BASE_URL=https://api.deepseek.com/anthropic \
  octo chat --model deepseek-chat "..."

# Enable the built-in tools (LLM can run shell commands, read/edit files, search, …)
octo chat --tools

# Sandbox those commands: confine the terminal tool to the project dir + tmp, no network
octo chat --tools --sandbox

# Generate a .octorules guide for this repo
octo init

# List discovered skills
octo chat --list-skills

Configuration

Octo composes its system prompt from several optional layers (later overrides earlier):

• ~/.octo/octorules.md — your global, cross-project rules and preferences.
• .octorules — per-repo conventions, committed with the project. Generate one with octo init (or /init in the REPL).
• --system "..." — a one-off override for a single run.

Both rule files support @include path/to/fragment.md to pull in shared content.

Skills

Skills are reusable instruction sets in Claude Code's SKILL.md format, discovered from:

• ~/.octo/skills/<name>/SKILL.md — user-level, across all projects.
• .octo/skills/<name>/SKILL.md — project-level (takes precedence over user-level).

The format is identical to Claude Code's, so you can symlink ~/.claude/skills to ~/.octo/skills and reuse what you already have. Each SKILL.md is YAML frontmatter plus a markdown body:

---
name: review
description: Review the current diff for correctness and style
---
Walk the diff hunk by hunk and flag correctness bugs first, then style.

At session start Octo lists each skill's name and description in the system prompt; the model loads a skill's full instructions on demand (via the skill tool) when a task matches. You can also trigger one explicitly — octo chat --list-skills to see what's discovered, then /skills to list and /<name> (e.g. /review) to run one in the REPL.

Sandboxing

--sandbox confines the terminal tool to the project directory plus temp, with no network, enforced by the OS (macOS Seatbelt, Linux Landlock + seccomp). It's off by default and fails closed when the OS mechanism is unavailable.

octo chat --tools --sandbox                              # confine, deny network
octo chat --tools --sandbox --sandbox-allow-net          # allow network
octo chat --tools --sandbox --sandbox-write ./build      # extra writable dir (repeatable)
octo chat --tools --sandbox --sandbox-read /opt/data     # extra readable dir (repeatable)

What's implemented

Area	Status	Description
Core CLI	done	Single-turn + interactive REPL, streaming, session persistence (~/.octo/sessions/), /cost /save /sessions
Providers	done	Anthropic Messages + OpenAI Chat Completions, plus any compatible third party
Tools	done	terminal (+ background), file read/write/edit, glob, grep, web fetch/search
Agentic loop	done	Multi-step tool calling, permission gating, history compaction, graceful Ctrl-C
Memory & config	done	~/.octo/octorules.md, .octorules, octo init, @include
Skills	done	Claude Code-compatible SKILL.md loader (--list-skills, /skills, /<name>)
Sandbox	done	OS-enforced --sandbox (macOS / Linux)
Web UI / IM bridges	planned	See dev-docs/go-rewrite-roadmap.md

Architecture

Layered, one-directional dependency graph:

cmd/octo/          CLI entry (chat, REPL, sessions, slash commands)
   ↓
internal/agent/    History, sessions, content blocks, Sender interface,
                   Agent.Turn / TurnStream / Run (tool-calling loop)
   ↓
internal/provider/ Provider interface + concrete implementations
                   ├─ anthropic/   x-api-key, system top-level, content[].text
                   └─ openai/      Bearer auth, system in messages[0]
   ↓
internal/tools/    ToolExecutor implementations — terminal (+ background),
                   file read/write/edit, glob, grep, web fetch/search, skill
internal/skills/   SKILL.md discovery + system-prompt manifest

Each provider implements both buffered (Send) and streaming (SendStream) variants. The agent layer mirrors with Sender / StreamingSender / ToolSender / ToolStreamingSender — interfaces are added incrementally so non-streaming providers still work.

Development

make build         # ./octo
make test          # go test -race ./...
make vet           # go vet ./...
make fmt-check     # gofmt -l . must be empty

See CLAUDE.md for the project guide intended for AI coding agents working in this repo, and CONTRIBUTING.md for the human PR workflow.

License

MIT. See LICENSE.txt.