Supported tools
The coding agents FusionKit can launch, and the behavior they share.
FusionKit launches an unmodified coding agent and backs it with a fused model panel. The agent speaks its normal wire protocol to a local gateway and never learns that fusion happened. Four agents share the neutral launcher path:
| Tool | Command | Gateway dialect | Install |
|---|---|---|---|
| Codex | fusionkit codex | OpenAI Responses (/v1/responses) | openai/codex |
| Claude Code | fusionkit claude | Anthropic Messages (/v1/messages) | Claude Code docs |
| Cursor | fusionkit cursor | OpenAI Chat, via the bundled Cursorkit bridge | cursor.com/cli |
| OpenCode | fusionkit opencode | OpenAI Chat through the generic driver | opencode.ai |
You only need the agent you plan to launch. fusionkit doctor checks which
binaries are on your PATH before a run.
What every launcher shares
Each launcher composes the configured RouteKit router, Python synthesizer, and
Fusion Harness Gateway, then receives the same neutral ToolLaunchSpec. One
Ctrl+C tears down Fusion-owned processes. External RouteKit daemons remain.
FusionKit's own flags come first; everything after the first forwarded
argument (or after --) goes to the agent untouched:
fusionkit claude --repo /path # --repo is a FusionKit flag
fusionkit codex -- "fix the build" # forwarded to codexThe behavior below works the same way in all four tools:
| Behavior | How |
|---|---|
| Fused model | The agent sees fusion-panel as a normal model. |
| Ensemble models | Each ensemble is fusion-<name>; the default is fusion-panel. |
| Rate-limit handoff | A throttled passthrough turn reruns on the panel by default. See Rate-limit handoff. |
| Durable sessions | --continue and --resume <id> restore a prior session. |
| Cost controls | --budget <usd> caps gateway-observed spend. See Cost and models. |
| Observability | --observe boots the local trace dashboard. |
| Sub-agents | Each named ensemble becomes a delegable sub-agent unless you pass --no-subagents. |
| Routing boundary | Ensemble members are live namespaced RouteKit model IDs. Use RouteKit for single-model launches. |
The per-tool pages cover what differs: how each agent is wired to the gateway, which environment the launcher sets, how the model picker is populated, and the tool-specific caveats.
Other clients
Anything that speaks the OpenAI Chat Completions API can use fusion without a
launcher. Run fusionkit serve and point the client at the printed URL with
model fusion-panel. See Inference endpoint.
To add a launcher for a new tool, see Adding a new tool.