Introduction
What FusionKit is, how the CLI and Python fusion engine fit together, and where to start.
What is FusionKit?
FusionKit runs ensembles of local and cloud models as a raw inference endpoint and behind your existing coding agent. On every fused turn it:
- Sends the request to the panel of live namespaced RouteKit model IDs configured for the selected ensemble.
- Captures each model's candidate response or harness trajectory.
- Runs a judge that synthesizes the candidates into the answer returned to your client, Codex, Claude Code, or Cursor.
You run one command and your agent is transparently backed by the panel:
npm install -g @fusionkit/cli
fusionkit setup
cd your-project # a git repo
fusionkit init # scaffold Fusion v4 + RouteKit config
fusionkit doctor # verify prerequisites
fusionkit codex # launch Codex backed by the panelTwo supported product paths
The Node @fusionkit/cli is the front door. It launches coding harnesses, owns
Fusion configuration, sessions, cost controls, and local-model management, and
starts the internal Python fusionkit-sidecar when synthesis is needed. The
Node Fusion gateway owns the public OpenAI-compatible endpoint; the sidecar has
only internal fusion/run routes.
Install the CLI
Back Codex, Claude Code, or Cursor with a fused model panel from one command.
Set up your tool
Per-tool guides for Codex, Claude Code, and Cursor: wiring, model pickers, sub-agents, and caveats.
Use the endpoint
Point OpenAI-compatible clients at fusionkit serve for fused chat,
streaming, and tool-calling.
Product scope
See which packages power the shipped product and which retained platform packages are legacy or contributor-only.
What is in the repository?
The repository still contains the older Warrant governance, handoff, SDK, Docker,
and VM-isolation stack under legacy/. It is real code retained for contributors,
but it is not the normal FusionKit product path and the shipped fusionkit CLI
does not ask you to run a legacy plane or runner.
The user-facing fusionkit executable comes only from @fusionkit/cli.
The PyPI fusionkit distribution is provisioned automatically via uvx and
exposes the internal fusionkit-sidecar executable, not a second
fusionkit command. fusionkit --version reports both package versions.
How these docs are organized
The sidebar follows reader intent, from first install to contract-level detail.
| Section | Read it when you want to | Contents |
|---|---|---|
| Get started | Install the CLI and run your first fused session. | Installation, quickstart. |
| Tools | Set up a specific coding agent. | One page each for Codex, Claude Code, and Cursor. |
| Guides | Complete a specific workflow. | Raw inference endpoint, rate-limit handoff, cost control, observability, troubleshooting, examples. |
| Concepts | Understand how the product fits together. | Panels, judges, model fusion, runtime kernel, product scope, privacy. |
| Reference | Look up an exact command, flag, or field. | Command reference, .fusionkit/ configuration, models and panels, package map. |
| API reference | Call FusionKit over HTTP. | Gateway routes and the generated harness-executor contract. |
| Changelog | See what changed in a release. | Release notes generated from the repository CHANGELOG.md. |