fusionkit: real model fusion behind your coding agent

RouteKit boundary

FusionKit composes @velum-labs/routekit-config, @velum-labs/routekit-router, gateway, and tool SDK packages. It does not install or invoke the routekit executable.

Install @velum-labs/routekit separately for provider/catalog/account/proxy management and single-model launches:

npm install -g @velum-labs/routekit
routekit providers status
routekit models list
routekit start
routekit codex openai/gpt-5.5

There are no FusionKit forwarding aliases.

RouteKit's public lifecycle is routekit start, routekit status, and routekit stop. Product commands also ensure the singleton daemon automatically. routekit daemon operations are advanced compatibility and administration paths, and there is no user-facing foreground serve command.

RouteKit remote gateways

Use named remotes when the RouteKit daemon runs on another machine behind an authenticated HTTPS endpoint:

Command	What it does
`routekit remote add <name> --url <https-url> --ssh <host>`	Verify the gateway, obtain its token over SSH, and make it active.
`routekit remote list`	List remotes without revealing tokens.
`routekit remote show [name]`	Probe HTTPS health and SSH control compatibility.
`routekit remote use <name>`	Set the persistent active remote.
`routekit remote use --none`	Return to the local daemon by default.
`routekit remote remove <name>`	Remove the record and stored token.

The global --remote <name> option overrides the active target for one invocation. Global --local forces the local daemon. Their precedence is --local, explicit --remote, active remote, then local. Launchers and model listing use the remote HTTPS data plane; control and administration commands use SSH and never expose the loopback control listener.

Fusion launch commands

Command	What it does
`fusionkit codex [args...]`	Launch Codex with configured fusion ensembles.
`fusionkit claude [args...]`	Launch Claude Code with configured fusion ensembles.
`fusionkit cursor [args...]`	Launch Cursor; `--ide` enables the desktop integration.
`fusionkit opencode [args...]`	Launch OpenCode through the generic driver path.
`fusionkit serve`	Run the Fusion gateway without launching a coding tool.

All four tools receive the same neutral ToolLaunchSpec. Each ensemble becomes a generic agent profile and fusion-<name> model; the default uses fusion-panel.

Fusion product commands

Command	What it does
`fusionkit init`	Scaffold Fusion v4 and safe RouteKit config.
`fusionkit setup`	Warm the pinned Python synthesis engine.
`fusionkit doctor`	Validate git, Fusion/RouteKit config, live models, uv, and tools.
`fusionkit config show\|path\|get\|set\|unset\|edit`	Inspect and edit Fusion v4.
`fusionkit ensemble list\|add\|edit\|remove\|rename`	Manage namespaced-model ensembles.
`fusionkit prompts list\|edit\|reset`	Manage judge/synthesizer prompts.
`fusionkit sessions list\|show\|rm`	Manage durable Fusion sessions.
`fusionkit models list\|download\|rm`	Manage the Fusion-owned local MLX cache.
`fusionkit stop`	Stop only Fusion-owned processes and portless routes.
`fusionkit telemetry`, `completion`, `version`	Telemetry, shell completion, and versions.

Removed surfaces include fusionkit proxy, account/CLIProxy management, coding-tool install/uninstall (routekit codex install|uninstall and routekit claude install|uninstall), --direct, and direct/single-model mode. Use RouteKit for those responsibilities.

Launch flags

Flag	Effect
`--ensemble <name>`	Select a configured ensemble.
`--repo <dir>`	Select the coding workspace.
`--observe` / `--no-observe`	Start or skip local observability.
`--reasoning` / `--no-reasoning`	Show or suppress fusion progress.
`--subagents` / `--no-subagents`	Create or suppress ensemble agent profiles.
`--port <n>`	Set the Fusion gateway port.
`--portless` / `--no-portless`	Enable or disable Fusion-owned named routes.
`--auth-token <token>`	Protect the Fusion gateway.
`--on-rate-limit fusion\|passthrough\|fail`	Select rate-limit behavior.
`--budget <usd>`	Set the session budget.
`--panel-trust full\|guarded`	Select panel worktree policy.
`--k <n>`	Set panel step boundaries.
`--resume <id>` / `--continue`	Resume a durable session.
`--ide`	Enable Cursor desktop wiring.
`--fusionkit-dir <dir>`	Use a local Python engine checkout.

Provider/model/key flags and --direct do not exist. Routing is configured in .routekit/router.yaml for an embedded Fusion router. The standalone RouteKit singleton uses its canonical global document; project files affect it only through an explicit routekit config import --from <path> replacement.

Ownership and shutdown

An embedded RouteKit router closes with its Fusion process. An external router is only connected to and is never killed by fusionkit stop or stack cleanup. Fusion sessions remain under @fusionkit/gateway.

Command reference