fractal

Hierarchical agent loops with recursive self-organization.

In a fractal, autonomous agent loops arrange themselves into a tree: a node iterates toward a goal in its own git worktree and spawns child nodes for separable subtasks, so the tree grows to fit the problem rather than a fixed plan. Hard caps (iterations, depth, children, cost, time) keep each loop bounded, and an operator can steer or stop it at any point. Run metadata (including cost) lands in one local SQLite database, which can be interacted with live in a terminal UI.

Source: https://github.com/plasma-ai/fractal

Package: https://pypi.org/project/plasma-fractal/

Documentation: https://docs.plasma.ai/fractal

Installation

Install the fractal package from PyPI:

pip install plasma-fractal

or

pip install fractal

Use pipx install or uv tool install to install the package in an isolated environment. If you use one of these two methods, you must also install plasma-wiki (a plain pip install pulls plasma-wiki and puts wiki on your PATH, but this is not the case when using pipx install or uv tool install).

uv tool install plasma-fractal --with-executables-from plasma-wiki does the same in one command.

Open the dashboard from your project root with fractal open (requires an initialized fractal). Pass --light if your terminal uses a light color scheme.

Skill

Install the skill for your agent via the plugin marketplace (Claude Code and Codex):

# Claude Code
/plugin marketplace add plasma-ai/plugins
/plugin install fractal@plasma

# Codex
codex plugin marketplace add plasma-ai/plugins
codex plugin add fractal@plasma

Another install route is from the CLI, which copies (or symlinks) the fractal and wiki skills into ~/.claude/skills and ~/.agents/skills (add --project for the current project only):

fractal install [--link]

After upgrading the package, re-run fractal install to refresh the copied skills (pass --link for symlinked install).

Usage

A fractal is a tree of git worktrees, each running an autonomous agent loop. The root (user) node is your current branch itself — it has no worktree or loop of its own; top-level nodes branch from it, and child nodes branch from their parent. Agents iterate in tmux sessions (or, with --headless, in detached process groups), and all state (runs, iters, steps, costs, signals) is tracked in a local SQLite database.

Five agent backends are supported — Claude Code (claude), Codex (codex), Grok Build (grok), OpenCode (opencode), and Oh My Pi (omp) — selected per node with --agent (children inherit it). Claude and Codex can additionally route through OpenRouter with --provider=openrouter, which authenticates via OPENROUTER_API_KEY from the launching shell; OpenCode and Oh My Pi reach OpenRouter natively through their own openrouter/<author>/<model> model ids.

Use the /fractal skill to spawn and manage agent nodes. The fractal CLI is also available directly — run fractal --help and fractal <command> --help to explore.

The skill is invoked as /fractal [directive] and takes plain-language instructions. The agent interprets the directive and prints any suggested NODE.md instructions and completion requirement it can distill from the directive, plus a table of every parameter (empty where the directive said nothing), then asks for anything it could not infer. From there it walks you through refining the node's definition and, once you approve, launches the node in a tmux session. On hosts where tmux cannot run, add --headless; the node's output appends to headless.log, delegated child starts follow the parent's backend, and an unflagged relaunch reuses the backend the node last launched with.

Parameters the skill interprets from the directive:

• name: node name (required; letters, digits, and _ only — no -)
• path: project root, repo root or monorepo sub-project (default: .)
• title: human-readable display name (default: de-slugged node name)
• scope: restrict commits to subdirectories within the worktree (comma-separated, e.g. parent/child,tests)
• base: branch to start from (default: current branch)
• meta: target node branch for meta-configuration
• inherit: seed surfaces from the parent node instead of the package seed (comma-separated: steps, scripts, skills, config, or all); agent config always inherits. A top-level spawn's parent is the user node, which carries no steps, scripts, or skills — the parameter is for configured nodes spawning children
• agent: agent command; inherits the user node's default when omitted
• provider: provider route for the agent (e.g. openrouter); inherits the user node's default when omitted
• model: model override; when omitted, the agent uses its own default model (Claude runs on the seed's best alias, or anthropic/claude-sonnet-4.6 when routed through OpenRouter)
• effort: reasoning-effort override; when omitted, the Claude and Codex seeds' own pinned level (high) applies rather than the vendor default, while Grok, OpenCode, and Oh My Pi fall back to the vendor default
• max-iters: per-run iteration cap
• max-depth: maximum child node nesting depth
• max-children: maximum direct child nodes
• max-descendants: maximum total descendant nodes
• timeout: per-run time limit (e.g. 30m, 1.5h)
• iter-timeout: per-iteration time limit (e.g. 30m, 1.5h)
• step-timeout: per-step time limit (e.g. 30s, 10m); caps each step
• interval: fixed iteration schedule (e.g. 1h)
• sleep: delay between iterations (e.g. 10s)
• wait: sleep between approval-wait sync invocations (default: 1m)
• max-cost: cost ceiling in USD per run — runs are isolated, so each launch arms the cap anew; after a budget-ended run, node start --continue refuses without an explicit --max-cost
• max-iter-cost: per-iteration cost ceiling in USD
• max-step-cost: per-step cost ceiling in USD (warn-only when unenforceable)
• reserve-budget: budget reserved for cleanup; USD or N% of max-cost (default: 10%)
• sync: enable (default) or disable radio sync before each step
• detached: run each step as a separate agent session (default: one continuous session)
• local: skip pushing to remote after each commit

Development

Install

Run install.sh in the package root. With no environment active it creates and uses a local .venv; with one active (e.g. pyenv) it installs into that environment (editable), without recreating it:

./install.sh --all-extras --groups=test,lint,type

Run ./install.sh --help for all options. Alternatively, run uv sync --all-extras --group test --group lint --group type and uv run pre-commit install to set up the environment manually.

Installing a dependency as editable (e.g. a sibling package) is left to the caller: uv pip install --editable <path>.

With an editable install, fractal install --link symlinks the bundled skill into the agent skill directories instead of copying it, so skill edits apply without re-running the install.

Once installed, run tools with uv run --no-sync <command>, or activate the environment first (source .venv/bin/activate).

Tests

Run the test suite:

pytest .

The suite runs with --doctest-modules enabled, and the integration tests create real git repositories and worktrees.

Linting

Run linters and formatters:

pre-commit run --all-files

Contributing

The contribution workflow, repository conventions, and release process (version sources, tagging, CI guard) are documented in:

• Contribution workflow (organization-wide): CONTRIBUTING.md
• Repository conventions: AGENTS.md
• Release process (organization-wide): RELEASING.md

Pull requests should be branched from dev, not main, and opened against dev — main only advances at releases.

License

Licensed under the Apache License 2.0 — see LICENSE.

Copyright © 2026 Plasma AI