Limbo

A terminal AI coding agent that is small enough to understand and sturdy enough to trust with long work.

Tell Limbo what you want in plain language. It explores your repository, reads and edits files, runs commands, and streams its reasoning and every tool call as it goes. When the work runs long, Limbo keeps it safe: every turn is journaled to disk, a crash or a closed terminal picks up where it stopped, and you can branch, hand off, or replay any session.

Who it's for

• Developers who live in the terminal and want an agent that fits next to their editor, multiplexer, and dotfiles instead of a separate app.
• People who use more than one model. DeepSeek, Kimi, GLM, OpenAI Codex, or any OpenAI-compatible endpoint, switchable mid-conversation.
• Anyone who wants to see what the agent did. Every request, tool call, and token is recorded and browsable; nothing happens off-screen.
• Hackers who want to read the code. Seven tools, one agent loop, plain JSONL on disk. AGENTS.md explains every design decision.

What you get

Work that survives

• Durable sessions. Messages, tool-call intents, queued follow-ups, and compactions are appended to a JSONL journal as they happen. Kill the process mid-turn and resume: read-only calls that were interrupted are re-run, calls that may have had side effects are flagged so the model checks before retrying, and nothing you queued is lost.
• Resume, branch, hand off. limbo --continue or /sessions to pick up, /fork to try another direction without touching the original, /handoff to start a clean context with a written brief that links back.
• Long runs stay alive. Automatic compaction summarizes old turns when the context fills up, while the full record stays in the journal.

You stay in control

• /plan puts the agent in read-only mode: it explores and proposes a step-by-step plan, while writes, edits, and mutating shell commands are blocked until you say /plan off.
• /goal <task> closes the loop: the model proposes a verify command, you confirm it, and Limbo iterates until it passes.
• Steer while it works. Type while a turn is running to redirect it; Alt+Enter queues a follow-up for after the task; Esc interrupts.
• Side channels. /btw <question> asks something quick without polluting the history; !<command> runs a shell command yourself, never sent to the model.

Any model, set up in seconds

• Guided setup. On first run with no key, Limbo asks for one and saves it to ~/.limbo/auth.json (readable only by you). limbo auth login verifies a key against the provider before saving; limbo models lists the catalog and which models are ready to use.
• Switch without restarting. Ctrl+L (or /model) opens a searchable picker with recent models first. Pick a model whose provider has no key yet and it asks for one inline. Shift+Tab steps through thinking levels.
• Three wire formats (OpenAI completions, Anthropic messages, OpenAI responses) behind one catalog, with per-provider overrides for relays, renamed key variables, and extra headers.

Fast turns

• Tool calls issued together run concurrently; edits to the same file are serialized.
• Code Mode (/code-mode) collapses the tool catalog into a single run_code tool: the model writes one Python program against a generated SDK, turning many round trips into one.

Nothing hidden

• /tracing-viewer opens a local web page with a live view of every LLM request, tool call, and token count in the session.
• /export dumps the session as a full JSONL log (request bodies, usage, tool results, errors) or as readable Markdown.

A TUI worth living in

• Limbo Dusk, the default theme, with limbo-dark and limbo-light alternatives, all checked for contrast.
• Follows Omarchy. On an Omarchy desktop Limbo picks up the system theme and switches live when you change it.
• Limbo Motion. Subtle animation that tells the story from unsettled to settled. Set [ui] motion = "reduced" or "off" if you prefer stillness (SSH sessions default to reduced).
• Ctrl+P command palette, image and file paste with Ctrl+V, collapsible tool output with Ctrl+O.

Scriptable

limbo --headless gives the same agent as a line-oriented REPL, and limbo --json prints one JSON event per line so scripts can drive it without parsing the screen. Inside the Herdr multiplexer, Limbo reports its working, idle, and blocked state to the pane.

Quick start

Requires Python 3.11 or later.

pip install limbo-code
cd ~/code/my-project
limbo                       # first run asks for an API key

Prefer to set up keys first:

limbo auth login            # choose a provider, paste a key, verified and saved
limbo auth list             # where each provider's key comes from
limbo models                # what you can run right now
limbo -m glm-4.7            # one run on a different model
limbo -m kimi-k3:high       # ...with a thinking level

Then just describe the task: "find why the login test is flaky and fix it".

Everyday use

From the shell: limbo --continue resumes the latest session for the current directory, limbo --resume <id-prefix> resumes any session.

Models and providers

Unknown model ids fall back to generic OpenAI-compatible defaults, and the model picker can connect any OpenAI-compatible endpoint. Everything can also live in ~/.limbo/config.toml:

[llm]
model = "deepseek-v4-pro"           # endpoint and key variable come from the catalog

[providers.codex]                   # override one provider only
base_url = "https://my-relay.example.com/v1"
api_key_env = "CODEX_API_KEY"
headers = { x-relay = "on" }

[ui]
theme = "auto"                      # Omarchy if installed, else limbo-dusk
motion = "full"                     # full | reduced | off

Make it yours

• Project instructions. Limbo reads AGENTS.md from the working directory and ~/.limbo/AGENTS.md into its system prompt.
• Skills. Drop a SKILL.md into <project>/.agents/skills/<name>/ or ~/.limbo/skills/<name>/. The model loads it when the task matches, or you call it as /<name>. See docs/skills.md.

Safety

There are no fences. Tools run immediately and unconfined: file tools honor absolute paths and symlinks anywhere, there is no sensitive-file blocklist, and bash runs every command as written, rm -rf included. Use /plan when you only want the agent to look, run Limbo with trusted models, and keep it in repositories you can afford to modify or lose.

[tools]
bash_enabled = false     # if you need a hard stop

Development

uv sync        # dev tools are a PEP 735 group, installed by default
make check     # sync + tests + lint + typecheck

Individually, always python -m pytest, never uv run pytest (which can fall through to a global pytest on PATH):

uv run python -m pytest tests/ -v
uv run ruff check src tests
uv run mypy src

The screenshot above is rendered from the real UI by scripts/readme_hero.py (uv run python scripts/readme_hero.py), so it can't drift from what ships.

Learn more

• AGENTS.md: architecture and design decisions
• CONTEXT.md: domain glossary
• docs/session-management.md: sessions, recovery, fork and handoff, tracing viewer
• docs/skills.md: writing skills
• design/: RFCs for headless mode, bang commands, and the UI