Cassady (cass) is a minimal Rust terminal coding agent with a looped chat UI, filesystem tools, access modes, JSONL conversation persistence, and OpenAI-compatible LLM support. The default endpoint is Fireworks.

Install

cargo install --path .

This installs both commands:

cass
cassady

Configure

On first run, Cass starts an interactive setup wizard if it cannot find a usable provider/model/API key:

cass

You can also run the wizard explicitly:

cass setup

The wizard uses clean keyboard prompts: ↑/↓ moves, Space selects providers, and Enter submits. It supports configuring multiple OpenAI-compatible providers at once: OpenAI, xAI, Fireworks, Groq, OpenRouter, OpenCode Zen, OpenCode Go, Cerebras, Novita, Together, and custom OpenAI-compatible endpoints. It asks for API key environment variables, tries to fetch models from GET /models, lets you retry model discovery or enter a model id manually if discovery fails, saves config, validates setup, and starts a new session when ready.

By default, Cass still ships with Fireworks defaults:

base URL: https://api.fireworks.ai/inference/v1
model: accounts/fireworks/models/qwen3p7-plus
API key: "$FIREWORKS_API_KEY"

Set your selected provider key, for example:

export FIREWORKS_API_KEY=...

User preferences live at ~/.cass/config.json:

{
  "default_model": "accounts/fireworks/models/qwen3p7-plus",
  "default_access_mode": "read-only",
  "show_reasoning": false
}

Provider connection details belong in ~/.cass/providers.json. Model metadata belongs in ~/.cass/models.json. API keys may be literal strings or environment-variable references like "$FIREWORKS_API_KEY".

Validate config with:

cass check

Extra global instructions can be placed in ~/.cass/global.md.

Bundled documentation from this build is embedded into the binary and installed to ~/.cass/docs on startup. See ~/.cass/docs/configuration.md for full configuration docs.

Usage

cass [--model MODEL] [--base-url URL] [--api-key-env ENV] [--cwd PATH]
cass --resume <chat-id>
cass --resume
cass check
cass setup

cass --resume without an ID lists chats for the current directory.

Keys

Type /: show command autocomplete, including command arguments like /model <model> and /new
Up/Down: move through an autocomplete menu
Enter: fill autocomplete selection when a menu is open; otherwise send message / run command
Tab: cycle reasoning effort (off → low → medium → high; required-reasoning models skip off)
Ctrl-J: insert newline
Shift-Tab: cycle access mode while idle (read-only → workspace-edit → full-access)
Ctrl-O: toggle compact/full tool output display
Ctrl-Shift-R: toggle reasoning display
Up/Down or mouse wheel: scroll transcript when no autocomplete menu is open
PageUp/PageDown: transcript scroll
Ctrl-C twice within 1.5 seconds: exit

Commands

cass check: validate Cass config files
cass setup: choose an OpenAI-compatible provider/model and save config
/model <model>: switch the model for future turns; model autocomplete lists entries from ~/.cass/models.json
/new: create a new chat for the current directory
/resume <chat>: resume a saved chat; chat autocomplete lists chats for the current directory
/status: show current chat status

On exit Cass prints:

Resume this chat with: cass --resume <id>

Tools

Tool calls are shown compactly by default; press Ctrl-O to expand full tool output.

Reasoning is hidden by default unless show_reasoning is enabled; press Ctrl-Shift-R to toggle it. Press Tab to choose the reasoning effort for future turns. Model metadata controls whether reasoning is supported or required and how the effort is sent to the provider. When providers stream reasoning fields, Cass persists that reasoning and sends it back in future model context using the provider's reasoning field, such as reasoning_content or reasoning.

Read-only mode allows ls, read, and grep within the launch cwd/--cwd and the bundled docs directory at ~/.cass/docs.

Workspace-edit mode allows ls, read, grep, write, and edit inside the launch workspace. Bundled Cass docs remain read-only. Shell commands are available but require explicit approval before execution.

Full-access mode additionally allows broader filesystem access under the user's OS permissions. Mutating tools use atomic writes where practical: Cass writes to a temporary file first, then renames it into place after validation/write success. write and edit are always blocked under ~/.cass/docs. The shell tool runs commands via sh -c in the launch working directory with a configurable timeout (default 30 seconds) and streams stdout/stderr into the transcript while the command is running.