FlyCrys

Native Linux GUI for Claude Code agents. One binary, starts in under a second, no Electron.

Why this exists

I've used Linux exclusively for 30 years. When Claude Code became my daily driver for writing software, the terminal worked but I kept hitting walls: can't preview images, can't see a file tree while the agent works, can't render markdown without switching to a browser, can't juggle multiple project streams without a mess of terminal tabs.

I didn't want Cursor or anything Electron-based. I wanted something native that feels like it belongs on a GTK desktop.

FlyCrys is not an IDE. It doesn't edit files. Agents do. You talk to agents, they write the code. FlyCrys gives you a workspace to manage that workflow: file tree on the left, viewer in the middle, agent chat on the right, terminal at the bottom. That's it.

What makes it different

• Only native Linux GUI for Claude Code — Opcode uses webview, Claude Desktop skips Linux entirely
• GTK4 native — follows system theme, integrates with GNOME, minimal resources
• Workspace-oriented — not just a chat wrapper; file tree, viewer, terminal, git panel, all wired together
• Agent profiles — preconfigured Security, Research, Default agents with custom system prompts and tool restrictions
• Zero cost — no subscription, no API proxy, uses your own Claude Code CLI
• Single binary — one cargo build, one .deb, done

Install

Debian / Ubuntu (recommended)

curl -fsSLo /tmp/flycrys.deb https://github.com/SergKam/FlyCrys/releases/latest/download/flycrys_amd64.deb
sudo apt install /tmp/flycrys.deb

To upgrade, run the same two commands. The URL always points to the latest release.

Build from source

# Ubuntu / Debian
sudo apt install libgtk-4-dev libvte-2.91-gtk4-dev libwebkitgtk-6.0-dev libjavascriptcoregtk-6.0-dev libsoup-3.0-dev

# Fedora
sudo dnf install gtk4-devel vte291-gtk4-devel webkitgtk6.0-devel

# Arch
sudo pacman -S gtk4 vte4 webkitgtk-6.0

git clone https://github.com/SergKam/FlyCrys.git
cd FlyCrys
cargo build --release
./target/release/flycrys

Prerequisites

FlyCrys requires the Claude Code CLI:

npm install -g @anthropic-ai/claude-code

Features

Agent chat

• Streaming markdown rendering (tables, code blocks, lists, blockquotes)
• Tool calls shown inline with spinners
• Pause, resume, stop agent processes
• Session resume across restarts
• Agent profiles with custom system prompts, tools, and model selection
• Image attachments via clipboard paste or file picker
• Drag files and folders into the prompt
• Bookmarks for reusable prompts
• Clickable file paths in responses open in the viewer
• Token usage and session cost in the status bar

Slash commands

Type / in the input to see all available commands with descriptions. Filters as you type.

Discovers commands from ~/.claude/commands/, ~/.claude/skills/, project .claude/, and installed plugins. Full CRUD dialog for managing skills and commands.

File tree

• Lazy-loading tree with system MIME-type icons
• Toolbar: Collapse All, Search (filters across entire project)
• Live refresh via inotify watcher (preserves expand state)
• Right-click: Copy Path, Add to Chat, Open Terminal Here, Open in Default App
• Drag files onto agent input
• Git status panel with color-coded changes

Text viewer

• Three-state mode: Source / Preview / Diff (segmented toggle)
• Syntax highlighting for 25+ languages
• Markdown preview in WebKitGTK
• Image preview with scaling
• Git diff with highlighting

Terminal

• Embedded VTE4 terminal with full PTY
• "Terminal here" opens in the file's directory
• Scrollback preserved across sessions
• Colors adapt to light/dark mode

Workspace

• Multi-tab workspaces, one per project
• Session persistence: window size, pane positions, open files, agent sessions
• Lazy tab loading: only the active tab builds at startup
• Light/dark theme toggle
• Desktop notifications when agents finish
• Git branch in status bar (updates via inotify, not polling)

Tech stack

System deps: GTK4, VTE4, WebKitGTK 6.0, libsoup 3.0

License

MIT. See LICENSE.