Cyril

The polished TUI for the Agent Client Protocol ecosystem.

What is this?

Cyril is a polished terminal interface for the Agent Client Protocol ecosystem. Run any of 37+ registered agents — Claude, Cursor, Codex, Cline, Goose, Kiro, and more — through a single interface. Beneath the TUI, composable proxy stages add behaviors no agent ships natively: skill systems, transcript audit, organizational permission policies, persistent memory across sessions, multi-client observers. Vendor neutrality is a feature, not a roadmap; stages are how cyril compounds value over time.

Status: Alpha. Today cyril works against Kiro CLI; vendor-neutral agent selection and the proxy-stage layer are in active development. The features and usage documentation below describe the current Kiro-focused implementation.

Features

• Streaming TUI — ratatui-based interface with real-time markdown rendering (headings, bold, italic, code blocks with syntax highlighting, tables, lists, blockquotes)
• Cross-platform — runs natively on Linux, macOS, and Windows
• 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 with inline diffs
• Approval prompts — review and approve command execution with Yes/Always/No options
• Session management — create, load, and resume previous sessions via /chat
• Agent/model switching — switch agents (/agent) and models (/model) via picker UI
• Live activity indicator — animated spinner with elapsed time and current tool activity in the toolbar
• Context bar — visual gauge showing context window usage
• @-file references — reference files in prompts with @path/to/file autocomplete

Prerequisites

• Kiro CLI installed and authenticated (kiro-cli login) — Linux, macOS, and Windows native binaries are all supported
• Rust toolchain (for building from source)

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+M	Toggle mouse capture (off = copy mode)
Ctrl+C / Ctrl+Q	Quit

Slash commands

Local commands (handled by Cyril):

Command	Description
/help	Show available commands
/new	Start a new session
/load <id>	Load a session by ID
/clear	Clear the chat
/mode <id>	Switch agent mode
/model [id]	Switch model (opens picker if no ID given)
/quit	Quit

Agent commands (forwarded to Kiro via ACP):

Command	Description
/agent	Switch agent (picker)
/chat	Resume a previous session (picker)
/compact	Compact conversation history
/context	Show context/token usage breakdown
/knowledge	Manage knowledge bases
/mcp	Show configured MCP servers
/plan	Switch to planning agent
/prompts	Select from available prompts (picker)
/tools	Show available agent tools
/usage	Show billing and usage info

Project structure

crates/
  cyril/          # TUI application (binary)
  cyril-core/     # Protocol logic, path translation, session state
docs/
  kiro-acp-protocol.md  # Comprehensive Kiro ACP protocol reference

License

MIT