feat: add comprehensive tree explorer integration with @-mention support

## Summary

- Add seamless integration with nvim-tree and neo-tree file explorers
- Implement @-mention functionality for files and directories via new ClaudeCodeTreeAdd and ClaudeCodeAdd commands
- Enable Claude to navigate and understand project file structures through visual selection
- Add support for new file creation in diff system with proper directory handling

## New Features

- **Tree Integration**: Context-aware <leader>as keybinding that sends text in normal buffers or adds files from tree explorers
- **@-mention Commands**:
  - `:ClaudeCodeTreeAdd` - Add selected files from tree explorers to Claude context
  - `:ClaudeCodeAdd <path> [start] [end]` - Add files/directories by path with optional line ranges
- **Enhanced Diff System**: Support for creating new files with automatic parent directory creation
- **Visual Selection**: Improved multi-file selection detection for both nvim-tree and neo-tree

## Technical Improvements

- Comprehensive test coverage with dedicated specs for @-mention functionality
- Improved error handling and user feedback for edge cases
- Enhanced build system with Nix integration for consistent development environment
- Code cleanup and maintainability improvements throughout codebase

## Breaking Changes

None - all changes are additive and backward compatible.

Fixes #14
Merge pull request #22 from coder/thomask33/nvim-tree-integration

Author: ThomasK33

.github/workflows/test.yml

@@ -59,12 +59,9 @@ jobs:
 
       - name: Generate coverage report
         run: |
-          # Check if stats file exists (created by busted --coverage)
           if [ -f "luacov.stats.out" ]; then
-            # Generate the regular luacov report
             nix develop .#ci -c luacov
 
-            # Create simple lcov.info from luacov.report.out
             echo "Creating lcov.info from luacov.report.out"
             {
               echo "TN:"
@@ -81,24 +78,20 @@ jobs:
               done
             } > lcov.info
 
-            # Create markdown coverage summary for GitHub Actions
             {
               echo "## 📊 Test Coverage Report"
               echo ""
 
-              # Extract overall coverage percentage
               if [ -f "luacov.report.out" ]; then
                 overall_coverage=$(grep -E "Total.*%" luacov.report.out | grep -oE "[0-9]+\.[0-9]+%" | head -1)
                 if [ -n "$overall_coverage" ]; then
                   echo "**Overall Coverage: $overall_coverage**"
                   echo ""
                 fi
 
-                # Create table header
                 echo "| File | Coverage |"
                 echo "|------|----------|"
 
-                # Extract file-by-file coverage
                 grep -E "^[^ ].*:" luacov.report.out | while read -r line; do
                   file=$(echo "$line" | cut -d':' -f1)
                   percent=$(echo "$line" | grep -oE "[0-9]+\.[0-9]+%" | head -1)

Makefile

@@ -1,26 +1,18 @@
 .PHONY: check format test clean
 
 # Default target
-all: check format
+all: format check test
 
 # Check for syntax errors
 check:
 	@echo "Checking Lua files for syntax errors..."
-	@find lua -name "*.lua" -type f -exec lua -e "assert(loadfile('{}'))" \;
+	nix develop .#ci -c find lua -name "*.lua" -type f -exec lua -e "assert(loadfile('{}'))" \;
 	@echo "Running luacheck..."
-	@luacheck lua/ tests/ --no-unused-args --no-max-line-length
+	nix develop .#ci -c luacheck lua/ tests/ --no-unused-args --no-max-line-length
 
 # Format all files
 format:
-	@echo "Formatting files..."
-	@if command -v nix >/dev/null 2>&1; then \
-		nix fmt; \
-	elif command -v stylua >/dev/null 2>&1; then \
-		stylua lua/; \
-	else \
-		echo "Neither nix nor stylua found. Please install one of them."; \
-		exit 1; \
-	fi
+	nix fmt
 
 # Run tests
 test:

README.md

@@ -49,8 +49,15 @@ Using [lazy.nvim](https://github.com/folke/lazy.nvim):
   "coder/claudecode.nvim",
   config = true,
   keys = {
+    { "<leader>a", nil, desc = "AI/Claude Code" },
     { "<leader>ac", "<cmd>ClaudeCode<cr>", desc = "Toggle Claude" },
     { "<leader>as", "<cmd>ClaudeCodeSend<cr>", mode = "v", desc = "Send to Claude" },
+    {
+      "<leader>as",
+      "<cmd>ClaudeCodeTreeAdd<cr>",
+      desc = "Add file",
+      ft = { "NvimTree", "neo-tree" },
+    },
   },
 }
 ```
@@ -60,13 +67,80 @@ That's it! For more configuration options, see [Advanced Setup](#advanced-setup)
 ## Usage
 
 1. **Launch Claude**: Run `:ClaudeCode` to open Claude in a split terminal
-2. **Send context**: Select text and run `:'<,'>ClaudeCodeSend` to send it to Claude
+2. **Send context**:
+   - Select text in visual mode and use `<leader>as` to send it to Claude
+   - In `nvim-tree` or `neo-tree`, press `<leader>as` on a file to add it to Claude's context
 3. **Let Claude work**: Claude can now:
    - See your current file and selections in real-time
    - Open files in your editor
    - Show diffs with proposed changes
    - Access diagnostics and workspace info
 
+## Commands
+
+- `:ClaudeCode` - Toggle the Claude Code terminal window
+- `:ClaudeCodeSend` - Send current visual selection to Claude, or add files from tree explorer
+- `:ClaudeCodeTreeAdd` - Add selected file(s) from tree explorer to Claude context (also available via ClaudeCodeSend)
+- `:ClaudeCodeAdd <file-path> [start-line] [end-line]` - Add a specific file or directory to Claude context by path with optional line range
+
+### Tree Integration
+
+The `<leader>as` keybinding has context-aware behavior:
+
+- **In normal buffers (visual mode)**: Sends selected text to Claude
+- **In nvim-tree/neo-tree buffers**: Adds the file under cursor (or selected files) to Claude's context
+
+This allows you to quickly add entire files to Claude's context for review, refactoring, or discussion.
+
+#### Features
+
+- **Single file**: Place cursor on any file and press `<leader>as`
+- **Multiple files**: Select multiple files (using tree plugin's selection features) and press `<leader>as`
+- **Smart detection**: Automatically detects whether you're in nvim-tree or neo-tree
+- **Error handling**: Clear feedback if no files are selected or if tree plugins aren't available
+
+### Direct File Addition
+
+The `:ClaudeCodeAdd` command allows you to add files or directories directly by path, with optional line range specification:
+
+```vim
+:ClaudeCodeAdd src/main.lua
+:ClaudeCodeAdd ~/projects/myproject/
+:ClaudeCodeAdd ./README.md
+:ClaudeCodeAdd src/main.lua 50 100    " Lines 50-100 only
+:ClaudeCodeAdd config.lua 25          " From line 25 to end of file
+```
+
+#### Features
+
+- **Path completion**: Tab completion for file and directory paths
+- **Path expansion**: Supports `~` for home directory and relative paths
+- **Line range support**: Optionally specify start and end lines for files (ignored for directories)
+- **Validation**: Checks that files and directories exist before adding, validates line numbers
+- **Flexible**: Works with both individual files and entire directories
+
+#### Examples
+
+```vim
+" Add entire files
+:ClaudeCodeAdd src/components/Header.tsx
+:ClaudeCodeAdd ~/.config/nvim/init.lua
+
+" Add entire directories (line numbers ignored)
+:ClaudeCodeAdd tests/
+:ClaudeCodeAdd ../other-project/
+
+" Add specific line ranges
+:ClaudeCodeAdd src/main.lua 50 100        " Lines 50 through 100
+:ClaudeCodeAdd config.lua 25              " From line 25 to end of file
+:ClaudeCodeAdd utils.py 1 50              " First 50 lines
+:ClaudeCodeAdd README.md 10 20            " Just lines 10-20
+
+" Path expansion works with line ranges
+:ClaudeCodeAdd ~/project/src/app.js 100 200
+:ClaudeCodeAdd ./relative/path.lua 30
+```
+
 ## How It Works
 
 This plugin creates a WebSocket server that Claude Code CLI connects to, implementing the same protocol as the official VS Code extension. When you launch Claude, it automatically detects Neovim and gains full access to your editor.
@@ -132,8 +206,15 @@ See [DEVELOPMENT.md](./DEVELOPMENT.md) for build instructions and development gu
   },
   config = true,
   keys = {
+    { "<leader>a", nil, desc = "AI/Claude Code" },
     { "<leader>ac", "<cmd>ClaudeCode<cr>", desc = "Toggle Claude" },
     { "<leader>as", "<cmd>ClaudeCodeSend<cr>", mode = "v", desc = "Send to Claude" },
+    {
+      "<leader>as",
+      "<cmd>ClaudeCodeTreeAdd<cr>",
+      desc = "Add file",
+      ft = { "NvimTree", "neo-tree" },
+    },
     { "<leader>ao", "<cmd>ClaudeCodeOpen<cr>", desc = "Open Claude" },
     { "<leader>ax", "<cmd>ClaudeCodeClose<cr>", desc = "Close Claude" },
   },

flake.lock

@@ -40,6 +40,7 @@
           luajitPackages.luacov
           neovim
           treefmt.config.build.wrapper
+          findutils
         ];
 
         # Development packages (additional tools for development)
@@ -49,7 +50,7 @@
           gnumake
           websocat
           jq
-          claude-code
+          # claude-code
         ];
       in
       {

flake.nix

@@ -18,7 +18,6 @@ M.defaults = {
 }
 
 --- Validates the provided configuration table.
--- Ensures that all configuration options are of the correct type and within valid ranges.
 -- @param config table The configuration table to validate.
 -- @return boolean true if the configuration is valid.
 -- @error string if any configuration option is invalid.
@@ -54,7 +53,6 @@ function M.validate(config)
     "visual_demotion_delay_ms must be a non-negative number"
   )
 
-  -- Validate diff_opts
   assert(type(config.diff_opts) == "table", "diff_opts must be a table")
   assert(type(config.diff_opts.auto_close_on_accept) == "boolean", "diff_opts.auto_close_on_accept must be a boolean")
   assert(type(config.diff_opts.show_diff_stats) == "boolean", "diff_opts.show_diff_stats must be a boolean")
@@ -65,8 +63,6 @@ function M.validate(config)
 end
 
 --- Applies user configuration on top of default settings and validates the result.
--- Merges the user-provided configuration with the default configuration,
--- then validates the merged configuration.
 -- @param user_config table|nil The user-provided configuration table.
 -- @return table The final, validated configuration table.
 function M.apply(user_config)