Cyril

A cross-platform TUI client for Kiro CLI via the Agent Client Protocol (ACP).

Status: Alpha — functional but under active development.

What is this?

Cyril is a terminal-based frontend for Kiro CLI, communicating over ACP (JSON-RPC 2.0 over stdio). It provides streaming markdown rendering, tool call visibility, and an approval workflow — all from your terminal.

On Linux — runs kiro-cli acp directly as a subprocess
On Windows — bridges to kiro-cli running inside WSL, with automatic path translation between C:\ and /mnt/c/ paths

Linux:   Cyril TUI  <── stdin/stdout JSON-RPC ──>  kiro-cli acp

Windows: Cyril TUI  <── stdin/stdout JSON-RPC ──>  WSL (kiro-cli acp)
              + automatic C:\ <-> /mnt/c/ path translation

Features

Streaming TUI — ratatui-based interface with real-time markdown rendering
Cross-platform — runs natively on Linux; bridges to WSL on Windows with automatic path translation
Hook system — JSON-configurable before/after hooks on file writes and terminal commands
Slash commands — autocomplete-enabled commands from both the client and the Kiro agent
Tool call display — see what the agent is doing in real time
Approval prompts — review and approve file writes and command execution
Session management — create, load, and switch between sessions

Prerequisites

Kiro CLI installed and authenticated (kiro-cli login)
Rust toolchain (for building from source)
Windows only: WSL with kiro-cli installed inside it

Installation

cargo install cyril

Or build from source:

git clone https://github.com/dwalleck/cyril.git
cd cyril
cargo build --release

The binary will be at target/release/cyril (or cyril.exe on Windows).

Usage

Launch the interactive TUI:

cyril

Send a one-shot prompt:

cyril --prompt "Explain what this project does"

Specify a working directory:

cyril -d /path/to/project        # Linux
cyril -d C:\Users\you\project    # Windows

Keyboard shortcuts

Key	Action
`Enter`	Send message
`Shift+Enter`	Newline in input
`Tab`	Accept autocomplete suggestion
`Esc`	Cancel current request
`Ctrl+C` / `Ctrl+Q`	Quit

Slash commands

Command	Description
`/help`	Show available commands
`/new`	Start a new session
`/load <id>`	Load a previous session
`/clear`	Clear the chat
`/quit`	Quit

Agent-provided slash commands are also available with autocomplete.

Hook system

Create a hooks.json in your working directory to configure hooks that run on agent actions:

{
  "hooks": [
    {
      "name": "Format on save",
      "event": "afterWrite",
      "pattern": "*.cs",
      "command": "dotnet format --include {{file}}"
    }
  ]
}

Hooks run at the protocol boundary — the agent never sees them, just the results.

Project structure

crates/
  cyril/          # TUI application (binary)
  cyril-core/     # Protocol logic, path translation, hooks, capabilities

License

MIT

cyril-core 0.1.0-alpha.1