> ## Documentation Index
> Fetch the complete documentation index at: https://docs.tryreplicas.com/llms.txt
> Use this file to discover all available pages before exploring further.

# fx

> Run fx agents through Vercel AI Gateway in Replicas workspaces.

Replicas supports [fx](https://github.com/vercel-labs/fx), Vercel Labs' native coding-agent harness.

## Setup

1. Create a key in [Vercel AI Gateway](https://vercel.com/ai-gateway).
2. Paste it under **fx → Vercel AI Gateway API Key** in [Coding Agents settings](https://tryreplicas.com/dashboard/agents).
3. Set an organization credential, or add a personal key to override it.

See [Credentials](/admin/credentials) for credential scope behavior.

## Using fx

Choose **fx** from the workspace agent picker. Replicas runs the pinned native binary through its Agent Client Protocol server, preserving sessions and streamed messages across turns.

fx can read and edit files, run commands, report tool progress, use Plan Mode, and interrupt active turns. It does not currently accept image attachments or support Codex goal mode.

Models come from Vercel AI Gateway. `zai/glm-5.2` is the default.

## Programmatic Use

Use `fx` anywhere Replicas accepts a coding-agent provider:

```bash theme={null}
replicas create fix-tests -e backend -a fx -m "Fix the failing tests"
replicas send REPLICA_ID -a fx -m "Run the tests again"
```

The [API](/features/api), [MCP](/features/mcp), [Automations](/features/automations), and [Defaults](/admin/defaults) surfaces also accept `fx`.