Add CLAUDE.md with development guidance

This file provides Claude Code with essential information about the project architecture, development commands, and key design patterns to enable more efficient code assistance.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: koki-develop

CLAUDE.md

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+# CLAUDE.md
+
+This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
+
+## Project Overview
+
+go-fzf is a Go library and CLI tool for creating fuzzy finders. It provides:
+- A library (`github.com/koki-develop/go-fzf`) for building custom fuzzy finders
+- A CLI tool (`gofzf`) that demonstrates the library's capabilities
+
+## Development Commands
+
+### Build
+```bash
+# Build the CLI tool
+go build ./cmd/gofzf
+```
+
+### Test
+```bash
+# Run all tests
+go test ./...
+
+# Run tests for a specific package
+go test ./search_test.go
+
+# Run a specific test
+go test -run TestName
+```
+
+### Lint
+```bash
+# Run golangci-lint (used in CI)
+golangci-lint run
+```
+
+## Architecture
+
+### Core Components
+
+1. **FZF struct** (`fzf.go`): Main entry point for the library
+   - `New()`: Creates a new fuzzy finder instance with options
+   - `Find()`: Launches the fuzzy finder and returns selected indexes
+   - `ForceReload()`: Forces reload when hot reload is enabled
+
+2. **Model** (`model.go`): Implements the Bubble Tea Model interface
+   - Manages UI state, cursor position, selections
+   - Handles window sizing and layout
+   - Integrates with Bubble Tea for terminal UI
+
+3. **Items** (`item.go`): Manages the list of searchable items
+   - Supports both static slices and hot-reloadable pointer-to-slice
+   - Provides thread-safe access for hot reload scenarios
+
+4. **Search** (`search.go`): Implements fuzzy search algorithm
+   - Case-sensitive/insensitive matching
+   - Returns matched indexes for highlighting
+
+5. **Options** (`option.go`): Configuration for fuzzy finder behavior
+   - UI customization (prompts, cursors, styles)
+   - Behavioral options (multiple selection, limits, case sensitivity)
+   - Keymaps and preview windows
+
+6. **Styles** (`styles.go`): Lipgloss styles for UI components
+   - Customizable colors and formatting
+   - Separate styles for different UI elements
+
+### Key Design Patterns
+
+- **Builder Pattern**: Options are configured through functional options
+- **Model-View Pattern**: Uses Bubble Tea's Model interface for UI state management
+- **Interface-based Design**: Items are accessed through reflection to support any slice type
+
+### Dependencies
+
+- **Bubble Tea**: Terminal UI framework
+- **Lipgloss**: Styling and layout
+- **Cobra**: CLI command framework (for gofzf)
+- **testify**: Testing assertions
+
+## Examples
+
+The `/examples` directory contains multiple demonstrations of library usage:
+- basic: Simple fuzzy finder
+- multiple: Multi-selection
+- hotreload: Dynamic item updates
+- styles: Custom styling
+- keymap: Custom key bindings
+- preview-window: Preview pane functionality