feat(websocket): implement complete RFC 6455 WebSocket server with zero dependencies

Change-Id: I5ca970785879454c215ddcfc5e65e59721b84590
Signed-off-by: Thomas Kosiewski <tk@coder.com>

Author: ThomasK33

ARCHITECTURE.md

@@ -10,12 +10,15 @@ The plugin establishes a bidirectional communication channel between Neovim and
 
 ### 1. WebSocket Server
 
-The WebSocket server is the communication backbone of the plugin:
+The WebSocket server is the communication backbone of the plugin, implemented using pure Neovim built-ins:
 
-- Implements JSON-RPC 2.0 message format
-- Listens on a dynamically selected port (10000-65535)
-- Handles client connections from Claude Code CLI
-- Dispatches incoming requests to appropriate handlers
+- **Pure Neovim Implementation**: Uses `vim.loop` (libuv) for TCP server operations
+- **RFC 6455 Compliant**: Full WebSocket protocol implementation
+- **JSON-RPC 2.0**: Standard message format for MCP communication
+- **Zero Dependencies**: No external libraries required
+- **Async Processing**: Non-blocking operations integrated with Neovim's event loop
+- **Multiple Clients**: Supports concurrent WebSocket connections
+- **Connection Management**: Ping/pong keepalive and graceful disconnection
 
 ```
 ┌─────────────┐                  ┌─────────────┐
@@ -25,6 +28,30 @@ The WebSocket server is the communication backbone of the plugin:
 └─────────────┘                  └─────────────┘
 ```
 
+**WebSocket Server Architecture:**
+
+```
+┌─────────────────┐
+│   TCP Server    │ ◄─── vim.loop.new_tcp()
+│  (vim.loop)     │
+└─────────┬───────┘
+          │
+┌─────────▼───────┐
+│ HTTP Upgrade    │ ◄─── WebSocket handshake
+│   Handler       │
+└─────────┬───────┘
+          │
+┌─────────▼───────┐
+│ WebSocket Frame │ ◄─── RFC 6455 frame processing
+│   Parser        │
+└─────────┬───────┘
+          │
+┌─────────▼───────┐
+│   JSON-RPC      │ ◄─── MCP message routing
+│  Message Router │
+└─────────────────┘
+```
+
 ### 2. Lock File System
 
 The lock file system enables Claude CLI to discover the Neovim integration:
@@ -149,21 +176,31 @@ lua/claudecode/
 ├── init.lua              # Main entry point and setup
 ├── config.lua            # Configuration management
 ├── server/
-│   ├── init.lua          # WebSocket server initialization
-│   ├── message.lua       # Message formatting and parsing
-│   └── handler.lua       # Request handlers
+│   ├── init.lua          # WebSocket server main interface with JSON-RPC 2.0
+│   ├── tcp.lua           # TCP server using vim.loop
+│   ├── utils.lua         # Utility functions (base64, SHA-1, HTTP parsing)
+│   ├── frame.lua         # WebSocket frame encoding/decoding (RFC 6455)
+│   ├── handshake.lua     # HTTP upgrade and WebSocket handshake
+│   ├── client.lua        # WebSocket client connection management
+│   └── mock.lua          # Mock server for testing
 ├── lockfile.lua          # Lock file management
 ├── tools/
-│   ├── init.lua          # Tool registration
-│   ├── file.lua          # File operation tools
-│   ├── editor.lua        # Editor information tools
-│   └── selection.lua     # Selection management tools
-├── selection.lua         # Selection tracking
-├── terminal.lua          # Terminal management (uses Snacks.nvim)
-├── environment.lua       # Environment variable management
-└── util.lua              # Utility functions
+│   └── init.lua          # Tool registration and dispatch
+├── selection.lua         # Selection tracking and notifications
+├── terminal.lua          # Terminal management (Snacks.nvim or native)
+└── meta/
+    └── vim.lua           # Vim API type definitions
 ```
 
+**WebSocket Server Implementation Details:**
+
+- **`server/tcp.lua`**: Creates TCP server using `vim.loop.new_tcp()`, handles port binding and client connections
+- **`server/handshake.lua`**: Processes HTTP upgrade requests, validates WebSocket headers, generates accept keys
+- **`server/frame.lua`**: Implements WebSocket frame parsing/encoding per RFC 6455 specification
+- **`server/client.lua`**: Manages individual WebSocket client connections and state
+- **`server/utils.lua`**: Provides base64 encoding, SHA-1 hashing, and XOR operations in pure Lua
+- **`server/init.lua`**: Main server interface that orchestrates all components and handles JSON-RPC messages
+
 ## Testing Architecture
 
 The testing strategy involves multiple layers:

CHANGELOG.md

@@ -1,6 +1,7 @@
 # Changelog
 
-All notable changes to the Claude Code Neovim Integration will be documented in this file.
+All notable changes to the Claude Code Neovim Integration will be documented in
+this file.
 
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
@@ -10,14 +11,24 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Added
 
 - Initial project structure and core modules
-- Basic WebSocket server implementation (placeholder)
+- **Complete WebSocket server implementation using pure Neovim built-ins**
+  - RFC 6455 compliant WebSocket protocol implementation
+  - JSON-RPC 2.0 message handling for MCP protocol
+  - Zero external dependencies (uses vim.loop, vim.json, vim.schedule)
+  - Support for multiple concurrent client connections
+  - Ping/pong keepalive and graceful connection management
+  - Full HTTP upgrade handshake with proper WebSocket accept key generation
+  - WebSocket frame encoding/decoding with masking support
 - Lock file management for Claude CLI discovery
 - Selection tracking for editor context
 - MCP tool implementations
 - Basic commands (:ClaudeCodeStart, :ClaudeCodeStop, :ClaudeCodeStatus, :ClaudeCodeSend)
 - Automatic shutdown and cleanup on Neovim exit
-- Testing framework with Busted
+- Testing framework with Busted (55 tests passing)
 - Development environment with Nix flakes
+- Comprehensive luacheck linting with zero warnings
+
+### Changed
 
 ## [0.1.0-alpha] - TBD
 

CLAUDE.md

@@ -25,7 +25,8 @@ The plugin follows a modular architecture with these main components:
 1. **WebSocket Server** (`lua/claudecode/server/init.lua`)
 
    - Handles communication with Claude Code CLI using JSON-RPC 2.0 protocol
-   - Currently uses placeholder implementations
+   - Pure Lua implementation with RFC 6455 WebSocket compliance
+   - Zero external dependencies
 
 2. **Lock File System** (`lua/claudecode/lockfile.lua`)
 
@@ -47,12 +48,14 @@ The plugin follows a modular architecture with these main components:
 
 ## Development Status
 
-The plugin is in alpha stage with:
+The plugin is in beta stage with:
 
 - Core structure and configuration system implemented
-- Basic lock file management implemented
-- Selection tracking implemented
-- WebSocket server and MCP tool implementation still using placeholders
+- Complete WebSocket server with RFC 6455 compliance
+- Enhanced selection tracking with multi-mode support
+- Lock file management implemented
+- MCP tool framework implemented
+- Comprehensive test suite (55 tests passing)
 
 ## Testing Approach
 
@@ -70,10 +73,10 @@ The project uses the Busted testing framework:
 
 Current priorities for development are:
 
-1. Implementing a real WebSocket server with lua-websockets or similar
-2. Implementing MCP tools for file operations and editor features
-3. Enhancing selection tracking
-4. Adding comprehensive integration tests
+1. Enhancing MCP tools with additional file operations and editor features
+2. Adding Neovim-specific tools (LSP integration, diagnostics, Telescope)
+3. Performance optimization for large codebases
+4. Integration testing with real Claude Code CLI
 
 ## Development Principles
 
@@ -89,7 +92,7 @@ Current priorities for development are:
 ## Dependencies & Requirements
 
 - Neovim >= 0.8.0
-- Lua >= 5.1
+- **Zero external dependencies** - Pure Lua implementation
 - Development tools:
   - LuaCheck for linting
   - StyLua for formatting

DEVELOPMENT.md

@@ -27,55 +27,59 @@ claudecode.nvim/
 
 ## Core Components Implementation Status
 
-| Component              | Status         | Priority | Notes                              |
-| ---------------------- | -------------- | -------- | ---------------------------------- |
-| Basic plugin structure | ✅ Done        | -        | Initial setup complete             |
-| Configuration system   | ✅ Done        | -        | Support for user configuration     |
-| WebSocket server       | 🚧 Placeholder | High     | Need real implementation           |
-| Lock file management   | ✅ Done        | -        | Basic implementation complete      |
-| Selection tracking     | ✅ Done        | -        | Basic implementation complete      |
-| MCP tools              | 🚧 Placeholder | High     | Need real implementation           |
-| Tests                  | 🚧 Started     | High     | Framework set up, examples created |
-| CI pipeline            | ✅ Done        | -        | GitHub Actions configured          |
-| Documentation          | ✅ Done        | -        | Initial documentation complete     |
+| Component              | Status     | Priority | Notes                                    |
+| ---------------------- | ---------- | -------- | ---------------------------------------- |
+| Basic plugin structure | ✅ Done    | -        | Initial setup complete                   |
+| Configuration system   | ✅ Done    | -        | Support for user configuration           |
+| WebSocket server       | ✅ Done    | -        | Pure Lua RFC 6455 compliant              |
+| Lock file management   | ✅ Done    | -        | Basic implementation complete            |
+| Selection tracking     | ✅ Done    | -        | Enhanced with multi-mode support         |
+| MCP tools              | 🚧 Started | Medium   | Basic framework, need more tools         |
+| Tests                  | ✅ Done    | -        | 55 tests passing, comprehensive coverage |
+| CI pipeline            | ✅ Done    | -        | GitHub Actions configured                |
+| Documentation          | ✅ Done    | -        | Complete documentation                   |
 
 ## Development Priorities
 
-1. **WebSocket Server Implementation**
+1. **MCP Tool Enhancement**
 
-   - Implement real WebSocket server using lua-websockets
-   - Add JSON-RPC 2.0 message handling
-   - Add client connection management
-   - Implement proper error handling
+   - Implement additional tools from the findings document
+   - Add Neovim-specific tools (LSP, diagnostics, Telescope integration)
+   - Enhance existing tool implementations
 
-2. **MCP Tool Implementation**
+2. **Performance Optimization**
 
-   - Implement all required tools from the findings document
-   - Map VS Code concepts to Neovim equivalents
-   - Test each tool thoroughly
+   - Monitor WebSocket server performance under load
+   - Optimize selection tracking for large files
+   - Fine-tune debouncing and event handling
 
-3. **Selection Tracking Enhancement**
+3. **User Experience**
 
-   - Improve selection change detection
-   - Ensure compatibility with various Neovim modes
-   - Optimize performance with proper debouncing
+   - Add more user commands and keybindings
+   - Improve error messages and user feedback
+   - Create example configurations for popular setups
 
 4. **Integration Testing**
-   - Develop comprehensive integration tests
-   - Create mock Claude client for testing
-   - Test edge cases and error handling
+   - Test with real Claude Code CLI
+   - Validate compatibility across Neovim versions
+   - Create end-to-end test scenarios
 
 ## Testing
 
 Run tests using:
 
 ```bash
 # Run all tests
-cd claudecode.nvim
-nvim --headless -u tests/minimal_init.lua -c "lua require('tests').run()"
+make test
 
 # Run specific test file
 nvim --headless -u tests/minimal_init.lua -c "lua require('tests.unit.config_spec')"
+
+# Run linting
+make check
+
+# Format code
+make format
 ```
 
 ## Implementation Guidelines
@@ -95,7 +99,7 @@ nvim --headless -u tests/minimal_init.lua -c "lua require('tests.unit.config_spe
 3. **Compatibility**
 
    - Support Neovim >= 0.8.0
-   - Minimize dependencies
+   - Zero external dependencies (pure Lua implementation)
    - Follow Neovim plugin best practices
 
 4. **Testing**
@@ -115,12 +119,13 @@ nvim --headless -u tests/minimal_init.lua -c "lua require('tests.unit.config_spe
 
 ### WebSocket Server
 
-The WebSocket server should use either:
+The WebSocket server is implemented in pure Lua with zero external dependencies:
 
-- [lua-resty-websocket](https://github.com/openresty/lua-resty-websocket) library
-- last resort, as unmaintained: [lua-websockets](https://github.com/lipp/lua-websockets)
-  library
-- Call out to a Node.js or Rust/Go server (if Lua implementation is problematic)
+- **Pure Neovim Implementation**: Uses `vim.loop` (libuv) for TCP operations
+- **RFC 6455 Compliant**: Full WebSocket protocol implementation
+- **JSON-RPC 2.0**: MCP message handling with proper framing
+- **Security**: Pure Lua SHA-1 implementation for WebSocket handshake
+- **Performance**: Optimized with lookup tables and efficient algorithms
 
 ### Custom Tools
 
@@ -133,7 +138,7 @@ Custom tools beyond the basic VS Code implementation could include:
 
 ## Next Steps
 
-1. Implement the WebSocket server with real functionality
-2. Complete the MCP tool implementations
-3. Add more comprehensive tests
-4. Create example configurations for popular Neovim setups
+1. Enhance MCP tool implementations with Neovim-specific features
+2. Add integration tests with real Claude Code CLI
+3. Optimize performance for large codebases
+4. Create example configurations for popular Neovim setups (LazyVim, NvChad, etc.)

README.md

@@ -8,7 +8,8 @@ A Neovim plugin that integrates with Claude Code CLI to provide a seamless AI co
 
 ## Features
 
-- 🔄 Bidirectional communication with Claude Code CLI
+- 🔄 **Pure Neovim WebSocket Server** - Zero external dependencies, uses only Neovim built-ins
+- 🌐 **RFC 6455 Compliant** - Full WebSocket protocol implementation with JSON-RPC 2.0
 - 🔍 Selection tracking to provide context to Claude
 - 🛠️ Integration with Neovim's buffer and window management
 - 📝 Support for file operations and diagnostics
@@ -19,9 +20,10 @@ A Neovim plugin that integrates with Claude Code CLI to provide a seamless AI co
 
 - Neovim >= 0.8.0
 - Claude Code CLI installed and in your PATH
-- Lua >= 5.1
 - **Optional for terminal integration:** [folke/snacks.nvim](https://github.com/folke/snacks.nvim) - Terminal management plugin (can use native Neovim terminal as an alternative).
 
+**Zero External Dependencies**: The WebSocket server is implemented using pure Neovim built-ins (`vim.loop`, `vim.json`, `vim.schedule`) with no external Lua libraries required.
+
 Note: The terminal feature can use `Snacks.nvim` or the native Neovim terminal. If `Snacks.nvim` is configured as the provider but is not available, it will fall back to the native terminal.
 
 ## Installation

flake.nix

@@ -42,9 +42,6 @@
             luajitPackages.busted
             luajitPackages.luacov
 
-            luajitPackages.luasocket
-            luajitPackages.lua-cjson
-
             ast-grep
             neovim
             luarocks

lua/claudecode/init.lua

@@ -83,6 +83,7 @@ function M.setup(opts)
   end
 
   M.state.config = vim.tbl_deep_extend("force", vim.deepcopy(default_config), opts)
+  vim.g.claudecode_user_config = vim.deepcopy(M.state.config) -- Make config globally accessible
 
   if terminal_opts then
     local terminal_setup_ok, terminal_module = pcall(require, "claudecode.terminal")

lua/claudecode/meta/vim.lua

@@ -25,11 +25,37 @@
 ---@field once boolean|nil
 ---@field on_close_timeout number|nil
 
+---@class vim_options_table: table<string, any>
+
+---@class vim_buffer_options_table: table<string, any>
+
+---@class vim_bo_proxy: vim_buffer_options_table
+---@operator index (key: number): vim_buffer_options_table # Allows vim.bo[bufnr]
+
+---@class vim_diagnostic_info
+---@field bufnr number
+---@field col number
+---@field end_col number|nil
+---@field end_lnum number|nil
+---@field lnum number
+---@field message string
+---@field severity number
+---@field source string|nil
+---@field user_data any|nil
+
+---@class vim_diagnostic_module
+---@field get fun(bufnr?: number, ns_id?: number): vim_diagnostic_info[]
+-- Add other vim.diagnostic functions as needed, e.g., get_namespace, set, etc.
+
 ---@class vim_global_api
 ---@field notify fun(msg: string | string[], level?: number, opts?: vim_notify_opts):nil
 ---@field log vim_log
 ---@field _last_echo table[]? # table of tables, e.g. { {"message", "HighlightGroup"} }
 ---@field _last_error string?
+---@field o vim_options_table # For vim.o.option_name
+---@field bo vim_bo_proxy      # For vim.bo.option_name and vim.bo[bufnr].option_name
+---@field diagnostic vim_diagnostic_module # For vim.diagnostic.*
+---@field empty_dict fun(): table # For vim.empty_dict()
 -- Add other vim object definitions here if they cause linting issues
 -- e.g. vim.fn, vim.api, vim.loop, vim.deepcopy, etc.