GitHub - undefinedopcode/kate-code: A Claude Code plugin for the Kate Editor leveraging Zed Industries claude-code-acp.

7 min read Original article ↗

Kate Code

A plugin for the Kate text editor that integrates Claude Code (an AI coding assistant) directly into the editor's interface. It provides an interactive chat panel where you can converse with Claude to get help with coding tasks—all without leaving your KDE development environment.

Kate Code Screenshot

Features

Chat Interface

  • Real-time Streaming: Messages stream in as Claude generates them with markdown formatting via marked.js
  • Syntax Highlighting: Language-aware code highlighting via highlight.js supporting 50+ languages
  • Theme Integration: Automatically adapts to your Kate/KDE color scheme (dark/light)
  • Copy Buttons: One-click clipboard copy on all code blocks

Tool Visualization

See what Claude is doing with inline tool call displays:

  • Bash: Command preview in header, full command and output in expandable details
  • Edit: Unified diffs with syntax-highlighted code showing exactly what changed
  • Write: Syntax-highlighted file content with copy button
  • Task/TaskOutput: Sub-agent status with badges for agent type, background execution, and resume state
  • Read/Glob/Grep: File operation summaries

Task Management

  • Collapsible task list showing multi-step operation progress
  • Real-time status: pending (○), in-progress (⟳), completed (✓)
  • Progress counter: "Tasks (3/5)" format
  • State persists across sessions via localStorage

Permission System

  • Inline permission dialogs for tool approvals
  • Options: Always Allow, Allow Once, Reject
  • Clear display of tool inputs and available actions

KDE Integration

  • Automatic color scheme extraction from ~/.config/kdeglobals
  • Kate theme colors applied to highlight.js syntax highlighting
  • Seamless side panel integration
  • Context-aware: passes current file, selection, and project root to Claude
  • Image paste support: paste images from clipboard directly into chat messages

Architecture

  • ACP Protocol: JSON-RPC 2.0 over stdin/stdout with claude-code-acp subprocess
  • Qt WebChannel: Bidirectional C++/JavaScript bridge for real-time UI updates
  • Web UI: HTML/CSS/JS rendered in Qt WebEngineView for rich formatting

Prerequisites

System Requirements

  • KDE Plasma / Kate text editor
  • Qt 6 (Core, Widgets, WebEngineWidgets, WebChannel)
  • KDE Frameworks 6 (KF6):
    • KTextEditor
    • KI18n
    • KCoreAddons
    • KXmlGui
  • CMake 3.16 or higher
  • C++17 compatible compiler

Runtime Dependencies

Installation

Install claude-code-acp

Follow the instructions at https://github.com/zed-industries/claude-code-acp to install the ACP binary.

Verify installation:

Option 1: Install from Package (Recommended)

Arch Linux (AUR or local build)

# Build and install from PKGBUILD
makepkg -si

Fedora / RHEL

# Build RPM using Docker
./build-packages.sh rpm

# Install the resulting package
sudo dnf install dist/kate-code-1.0.0-1.*.rpm

Debian / Ubuntu

# Build deb using Docker
./build-packages.sh deb

# Install the resulting package
sudo dpkg -i dist/kate-code_1.0.0-1_amd64.deb
sudo apt-get install -f  # Install any missing dependencies

Option 2: Build from Source

Install Build Dependencies

Arch Linux / Manjaro:

sudo pacman -S cmake extra-cmake-modules qt6-webengine \
  kf6-ktexteditor kf6-ki18n kf6-kcoreaddons kf6-kxmlgui kf6-syntax-highlighting

Debian / Ubuntu:

sudo apt install cmake extra-cmake-modules qt6-webengine-dev \
  libkf6texteditor-dev libkf6i18n-dev libkf6coreaddons-dev \
  libkf6xmlgui-dev libkf6syntaxhighlighting-dev

Fedora:

sudo dnf install cmake extra-cmake-modules gcc-c++ qt6-qtwebengine-devel \
  kf6-ktexteditor-devel kf6-ki18n-devel kf6-kcoreaddons-devel \
  kf6-kxmlgui-devel kf6-syntax-highlighting-devel

Build and Install

# Configure
cmake -B build -DCMAKE_BUILD_TYPE=Release

# Build
cmake --build build

# Install to system (requires sudo)
sudo cmake --install build

# Or install to user directory
cmake --install build --prefix ~/.local

The plugin will be installed to:

  • Library: /usr/lib/qt6/plugins/kf6/ktexteditor/katecode.so
  • Metadata: /usr/lib/qt6/plugins/kf6/ktexteditor/katecode.json
  • UI Resource: /usr/share/kate/plugins/katecode/katecodeui.rc

Enable in Kate

  1. Restart Kate completely (close all windows)
  2. Open Kate
  3. Go to Settings → Configure Kate → Plugins
  4. Find and enable Kate Code
  5. Click OK

Usage

Starting a Session

  1. The Kate Code panel appears in Kate's side panel area (left or right sidebar)
  2. Click the Connect button to start a claude-code-acp session
  3. The plugin will initialize using your current project's directory as the working directory

Sending Messages

  • Type your message in the input field at the bottom
  • Press Enter to send (Shift+Enter for newline)
  • Claude's response will stream in real-time with markdown formatting

Agent Mode

Use the dropdown next to the input field to select Claude's operating mode:

  • Default: Standard interactive mode with tool permission prompts
  • Plan Mode: Claude will create a plan before executing tasks
  • Additional modes may be available depending on your claude-code configuration

Code Blocks

When Claude shows code in responses:

  • Syntax highlighting is applied automatically based on the language
  • Click the 📋 copy button in the top-right corner of any code block to copy to clipboard
  • Highlighting theme automatically matches your KDE color scheme (light/dark)

Context Awareness

The plugin automatically provides context to Claude:

  • Current File: If you have a file open, Claude knows which file you're working on
  • Selection: If you have text selected, it's passed to Claude as context
  • Project Root: Automatically detected from:
    • Kate's project plugin (if available)
    • VCS markers (.git, .hg, .svn)
    • Build files (CMakeLists.txt, package.json, Cargo.toml, etc.)
    • IDE markers (.idea, .vscode, .kate-project)

Tool Calls

When Claude uses tools, they appear inline in the conversation:

  • Collapsed view: Shows tool name and key info (command for Bash, filename for file ops)
  • Expanded view: Click to see full command/input and complete output
  • Status indicators: Visual feedback for pending, running, completed, or failed operations

Task List

  • Appears at the bottom of the chat when Claude is working on multi-step tasks
  • Click the header to collapse/expand (state persists across sessions)
  • Shows progress counter: "Tasks (3/5)" means 3 completed out of 5 total
  • Icons:
    • ○ Pending task
    • ⟳ Currently working (animated)
    • ✓ Completed task

Permissions

When Claude needs approval to run certain tools:

  • A permission dialog appears inline in the chat
  • Shows the tool name, input details, and available options
  • Options typically include: "Always Allow", "Allow", "Reject"
  • Click an option to respond

Session Summarization & Resume (Experimental)

Kate Code includes experimental support for session summarization and context re-seeding:

  • Automatic Summarization: When a session ends, the conversation is summarized and stored locally
  • Context Resume: Starting a new session can optionally re-seed context from the previous summary
  • Continuity: Helps maintain context across editor restarts or when switching between tasks

Setup: This feature requires an Anthropic API key, which can be configured in the plugin settings (Settings → Configure Kate → Kate Code). The API key is securely stored in KWallet.

This feature is experimental and behavior may change in future releases.

Configuration

Color Scheme

The plugin automatically adapts to your KDE color scheme by reading ~/.config/kdeglobals. If you change your KDE theme, restart Kate to pick up the new colors.

Troubleshooting

Plugin not showing in Kate

  • Verify the plugin is installed: ls /usr/lib/qt6/plugins/kf6/ktexteditor/katecode.so
  • Check Kate's plugin list: Settings → Configure Kate → Plugins
  • Restart Kate completely (close all windows)

Connection fails

  • Verify claude-code-acp is in PATH: which claude-code-acp
  • Look for error messages in terminal when launching Kate from command line: kate

Messages not displaying

  • Open browser dev tools: The WebView uses Chromium, accessible on localhost:9222
  • Check terminal output for JavaScript errors

Build errors

  • Ensure all KF6 dependencies are installed
  • Check CMake output for missing packages
  • Verify Qt 6 and KDE Frameworks 6 versions are compatible

Development

Project Structure

kate-code/
├── CMakeLists.txt              # Root build configuration
├── src/
│   ├── CMakeLists.txt          # Source build configuration
│   ├── katecode.json           # Plugin metadata
│   ├── katecode.qrc            # Qt resources (web assets)
│   ├── plugin/                 # Kate plugin integration
│   │   ├── KateCodePlugin.*    # Plugin factory
│   │   └── KateCodeView.*      # Per-window view, context providers
│   ├── acp/                    # ACP protocol implementation
│   │   ├── ACPModels.h         # Data structures
│   │   ├── ACPService.*        # QProcess subprocess management
│   │   └── ACPSession.*        # Protocol flow, message parsing
│   ├── ui/                     # User interface components
│   │   ├── ChatWidget.*        # Main container
│   │   ├── ChatWebView.*       # WebEngine view + JS bridge
│   │   ├── ChatInputWidget.*   # Multiline text input
│   │   └── PermissionDialog.*  # Permission approval UI
│   ├── util/                   # Utilities
│   │   └── KDEColorScheme.*    # KDE color extraction
│   └── web/                    # Web UI assets
│       ├── chat.html           # Chat page
│       ├── chat.css            # Styles
│       └── chat.js             # Message rendering, interactivity

Building for Development

# Build without installing
cmake -B build
cmake --build build

# Install to user location (if supported)
cmake --install build --prefix ~/.local

# Rebuild after changes
cmake --build build
sudo cmake --install build

Debug Logging

The plugin outputs debug information to stdout/stderr. Run Kate from terminal to see logs:

kate 2>&1 | grep -E "\[ACP|ChatWebView|ChatWidget\]"

License

MIT License

Contributing

Contributions welcome! Please:

  1. Fork the repository
  2. Create a feature branch
  3. Make your changes
  4. Submit a pull request

Acknowledgments

  • Built with Qt 6 and KDE Frameworks 6
  • Integrates with claude-code-acp by Zed Industries
  • Markdown rendering by marked.js