personotes/CLAUDE.md

# CLAUDE.md

This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.

## Project Overview

A lightweight web-based Markdown note-taking application with a Go backend and modern JavaScript frontend. Notes are stored as plain Markdown files with YAML front matter containing metadata (title, date, last_modified, tags). The system provides a sophisticated CodeMirror 6 editor with live preview, rich search capabilities, hierarchical organization, and automatic front matter management.

**Key Features**:
- **Daily Notes**: Quick daily journaling with interactive calendar, keyboard shortcuts (Ctrl/Cmd+D), and structured templates
- **Favorites System**: Star important notes and folders for quick access from the sidebar
- **Note Linking**: Create links between notes with `/link` command and fuzzy search modal
- **Vim Mode**: Full Vim keybindings support (hjkl navigation, modes, commands) for power users
- **Multiple Themes**: 8 dark themes (Material Dark, Monokai, Dracula, One Dark, Solarized, Nord, Catppuccin, Everforest)
- **Font Customization**: 8 fonts (JetBrains Mono, Fira Code, Inter, etc.) with 4 size options
- **Keyboard Shortcuts**: 10+ global shortcuts for navigation, editing, and productivity

**Recent Modernization**: The project has been migrated from a simple textarea editor to CodeMirror 6, with a Vite build system for frontend modules. The backend remains unchanged, maintaining the same Go architecture with htmx for dynamic interactions.

## Architecture

### Backend (Go)

Four main packages under `internal/`:
- **indexer**: Maintains an in-memory index mapping tags to note files. Parses YAML front matter from `.md` files to build the index. Thread-safe with RWMutex.
- **watcher**: Uses `fsnotify` to monitor filesystem changes and trigger re-indexing with 200ms debounce. Recursively watches all subdirectories.
- **api**: HTTP handlers that serve templates and handle CRUD operations on notes. Updates front matter automatically on save.
  - `handler.go` - Main HTML endpoints for the web interface
  - `rest_handler.go` - REST API endpoints (v1)
  - `daily_notes.go` - Daily note creation and calendar functionality
  - `favorites.go` - Favorites management (star/unstar notes and folders)

The server (`cmd/server/main.go`) coordinates these components:
1. Loads initial index from notes directory
2. Starts filesystem watcher for automatic re-indexing
3. Pre-parses HTML templates from `templates/`
4. Serves routes:
   - `/` (main page)
   - `/api/v1/notes` and `/api/v1/notes/*` (REST API - JSON responses)
   - `/api/search` (HTML search results)
   - `/api/notes/*` (HTML editor for notes)
   - `/api/tree` (HTML file tree)
   - `/api/folders/create` (Folder management)
   - `/api/files/move` (File/folder moving)
   - `/api/home` (Home page)
   - `/api/daily-notes/*` (Daily note creation and calendar)
   - `/api/favorites/*` (Favorites management)
5. Handles static files from `static/` directory

### Frontend

The frontend uses a modern build system with Vite and CodeMirror 6:

#### Architecture
- **Build System**: Vite compiles frontend modules from `frontend/src/` to `static/dist/`
- **Editor**: CodeMirror 6 with Markdown language support, One Dark theme, and syntax highlighting
- **Templates**: `index.html`, `editor.html`, `file-tree.html`, `search-results.html`, `new-note-prompt.html`
- **HTMX Integration**: Server returns HTML fragments that htmx swaps into the DOM
- **Out-of-band swaps**: Update the file tree after saves/deletes without full page reload

#### Frontend Source Structure
```
frontend/src/
├── main.js                  # Entry point - imports all modules
├── editor.js                # CodeMirror 6 editor implementation with slash commands
├── vim-mode-manager.js      # Vim mode integration for CodeMirror
├── search.js                # Search modal with Ctrl/Cmd+K keyboard shortcut
├── link-inserter.js         # Note linking modal for /link command
├── file-tree.js             # Drag-and-drop file organization
├── favorites.js             # Favorites system (star/unstar functionality)
├── daily-notes.js           # Daily notes creation and calendar widget
├── keyboard-shortcuts.js    # Global keyboard shortcuts management
├── theme-manager.js         # Theme switching and persistence
├── font-manager.js          # Font selection and size management
└── ui.js                    # Sidebar toggle functionality
```

#### CodeMirror 6 Editor Features
- **Syntax Highlighting**: Full Markdown language support (`@codemirror/lang-markdown`)
- **Theme**: One Dark theme (`@codemirror/theme-one-dark`) - VS Code-inspired dark theme
- **Vim Mode**: Optional full Vim keybindings (`@replit/codemirror-vim`) with hjkl navigation, modes, and commands
- **Live Preview**: Debounced updates (150ms) synchronized with editor scroll position
- **Auto-Save**: Triggers after 2 seconds of inactivity
- **Keyboard Shortcuts**:
  - `Ctrl/Cmd+S` for manual save
  - `Ctrl/Cmd+D` for daily notes
  - `Ctrl/Cmd+K` for search
  - `Ctrl/Cmd+B` for sidebar toggle
  - `Tab` for proper indentation
  - Full keyboard navigation (see docs/KEYBOARD_SHORTCUTS.md)
- **View Modes**: Toggle between split view, editor-only, and preview-only
- **Slash Commands**: Type `/` to open command palette for quick Markdown insertion
- **Front Matter Handling**: Automatically strips YAML front matter in preview

#### File Tree Features
- **Folder Management**: Expand/collapse folders with visual indicators (📁/📂)
- **Drag & Drop**: Move files between folders with visual feedback
- **Folder Creation**: Modal-based creation supporting nested paths
- **Safe Validation**: Prevents dangerous path operations
- **Favorites**: Star notes and folders for quick access (★ icon in sidebar)

#### Rendering Pipeline
- **marked.js**: Markdown to HTML conversion
- **DOMPurify**: HTML sanitization to prevent XSS attacks
- **Highlight.js**: Syntax highlighting for code blocks in preview
- **Custom Themes**: 8 dark themes in `static/theme.css` with CSS custom properties
  - Material Dark (default)
  - Monokai
  - Dracula
  - One Dark
  - Solarized Dark
  - Nord
  - Catppuccin
  - Everforest

### HTMX + JavaScript Coordination (Optimized Architecture)

**Key Principle**: HTMX handles ALL server interactions and DOM updates. JavaScript handles UI enhancements (editor, drag-and-drop, animations).

#### Architecture Flow
```
User Interaction → HTMX (AJAX) → Go Server (HTML) → HTMX (DOM update) → JS Events (enhancements)
```

#### Best Practices

**1. Use `htmx.ajax()` for JavaScript-initiated requests:**
```javascript
// ✅ Good: Let HTMX handle the request and DOM updates
htmx.ajax('POST', '/api/files/move', {
    values: { source, destination },
    swap: 'none'  // Server uses hx-swap-oob
});

// ❌ Bad: Manual fetch + DOM manipulation
const response = await fetch('/api/files/move', {...});
const html = await response.text();
target.innerHTML = html;
htmx.process(target);  // This is now unnecessary
```

**2. Listen to HTMX events instead of DOM observers:**
```javascript
// ✅ Good: React to HTMX swaps
document.body.addEventListener('htmx:afterSwap', (event) => {
    if (event.detail.target.id === 'file-tree') {
        updateDraggableAttributes();
    }
});

document.body.addEventListener('htmx:oobAfterSwap', (event) => {
    if (event.detail.target.id === 'file-tree') {
        updateDraggableAttributes();
    }
});

// ❌ Bad: MutationObserver (performance overhead)
const observer = new MutationObserver(() => {...});
observer.observe(element, { childList: true, subtree: true });
```

**3. Let HTMX process out-of-band swaps automatically:**
The server returns HTML with `hx-swap-oob` attributes. HTMX automatically finds these elements and swaps them, even when they're not the primary target.

```go
// Server response (Go template)
<div id="file-tree" hx-swap-oob="innerHTML">
    <!-- Updated file tree HTML -->
</div>
```

HTMX automatically:
- Finds the element with `id="file-tree"`
- Replaces its innerHTML
- Processes any HTMX attributes in the new content
- Triggers `htmx:oobAfterSwap` event

**4. Event-driven architecture:**
```javascript
// File tree initialization (file-tree.js)
class FileTree {
    constructor() {
        this.init();
    }

    init() {
        // Use event delegation on stable parent
        const sidebar = document.getElementById('sidebar');

        // Click handlers (delegated)
        sidebar.addEventListener('click', (e) => {
            const folderHeader = e.target.closest('.folder-header');
            if (folderHeader) this.toggleFolder(folderHeader);
        });

        // Drag-and-drop handlers (delegated)
        sidebar.addEventListener('dragstart', (e) => {...});
        sidebar.addEventListener('drop', (e) => {...});

        // React to HTMX updates
        document.body.addEventListener('htmx:oobAfterSwap', (event) => {
            if (event.detail.target.id === 'file-tree') {
                this.updateDraggableAttributes();
            }
        });
    }
}
```

#### Implementation Examples

**Creating a folder (file-tree.js:438-476)**:
```javascript
htmx.ajax('POST', '/api/folders/create', {
    values: { path: folderName },
    swap: 'none'  // Server handles oob swap
}).then(() => {
    hideNewFolderModal();
}).catch(() => {
    alert('Erreur lors de la création du dossier');
});
```

**Moving a file (file-tree.js:338-362)**:
```javascript
htmx.ajax('POST', '/api/files/move', {
    values: { source: sourcePath, destination: destinationPath },
    swap: 'none'  // Server handles oob swap
}).then(() => {
    console.log('File moved successfully');
});
```

#### Benefits of This Architecture

1. **Less Code**: ~60 lines removed by eliminating manual DOM manipulation
2. **Better Performance**: HTMX events instead of MutationObserver
3. **Consistency**: All server interactions use the same pattern
4. **Maintainability**: Clear separation between HTMX (data) and JavaScript (UI enhancements)
5. **Reliability**: HTMX handles edge cases (race conditions, partial updates, etc.)

#### When to Use What

**Use HTMX for:**
- Loading content from server
- Form submissions
- Search/filtering
- File operations (move, delete, create)
- Automatic DOM updates

**Use JavaScript for:**
- CodeMirror editor initialization
- Drag-and-drop UI logic
- Slash command palette
- Scroll synchronization
- View mode toggles
- Client-side animations

**Never:**
- Parse HTML manually from fetch() responses
- Call `htmx.process()` manually (HTMX does it automatically)
- Use MutationObserver when HTMX events are available
- Mix fetch() and htmx.ajax() for similar operations

### Daily Notes

**Implementation**: `internal/api/daily_notes.go` and `frontend/src/daily-notes.js`

Daily notes provide a quick journaling feature:
- **Keyboard Shortcut**: `Ctrl/Cmd+D` creates or opens today's note
- **Calendar Widget**: Interactive monthly calendar showing all daily notes
- **Template System**: Uses `daily-note-template.md` if present in notes directory
- **Auto-naming**: Creates notes as `daily/YYYY-MM-DD.md` by default
- **Visual Indicators**: Calendar highlights days with existing notes
- **One-click Access**: Click any calendar date to open or create that day's note

The calendar is implemented using htmx for dynamic month navigation and rendering.

### Favorites System

**Implementation**: `internal/api/favorites.go` and `frontend/src/favorites.js`

The favorites system allows quick access to frequently used notes and folders:
- **Star Icon**: Click ★ next to any note or folder in the file tree
- **Persistence**: Favorites stored in `.favorites.json` in the notes directory
- **Quick Access**: Starred items appear at the top of the sidebar
- **Folder Support**: Star entire folders to quickly access project areas
- **Visual Feedback**: Filled star (★) for favorites, empty star (☆) for non-favorites

Favorites are loaded on server startup and updated in real-time via htmx.

### Note Format

Notes have YAML front matter with these fields:
```yaml
---
title: "Note Title"
date: "08-11-2025"
last_modified: "08-11-2025:13:02"
tags: [tag1, tag2]
---
```

The `indexer` package handles both single-value and array-format tags via custom `UnmarshalYAML`.

## Development Commands

### Building the Frontend

**IMPORTANT**: The frontend must be built before running the application. The compiled JavaScript is required.

```bash
cd frontend
npm install          # Install dependencies (first time only)
npm run build       # Compile frontend modules to static/dist/
```

Output files (loaded by templates):
- `static/dist/project-notes-frontend.es.js` (ES module)
- `static/dist/project-notes-frontend.umd.js` (UMD format)

Frontend dependencies (from `frontend/package.json`):
- `@codemirror/basic-setup` (^0.20.0) - Base editor functionality
- `@codemirror/lang-markdown` (^6.5.0) - Markdown language support
- `@codemirror/state` (^6.5.2) - Editor state management
- `@codemirror/view` (^6.38.6) - Editor view layer
- `@codemirror/theme-one-dark` (^6.1.3) - Dark theme
- `@replit/codemirror-vim` (^6.2.2) - Vim mode integration
- `vite` (^7.2.2) - Build tool

### Running the Server

```bash
go run ./cmd/server
```

Server starts on `http://localhost:8080`. Use flags to customize:
- `-addr :PORT` - Change server address (default: `:8080`)
- `-notes-dir PATH` - Change notes directory (default: `./notes`)

### Testing

Run all tests:
```bash
go test ./...
```

Run specific package tests:
```bash
go test ./internal/indexer
go test ./internal/api
```

Run tests with verbose output:
```bash
go test -v ./...
```

### Building the Server Binary

```bash
go build ./cmd/server
```

### Backend Dependencies

Update Go dependencies:
```bash
go mod tidy
```

Key backend dependencies:
- `github.com/fsnotify/fsnotify` - Filesystem watcher
- `gopkg.in/yaml.v3` - YAML parsing for front matter

### Vite Build System

The frontend uses Vite (`frontend/vite.config.js`) for bundling JavaScript modules:

**Configuration**:
- **Entry Point**: `frontend/src/main.js` (imports editor.js, file-tree.js, ui.js)
- **Output Directory**: `static/dist/` (served by Go server)
- **Library Mode**: Builds as a library with both ES and UMD formats
- **Single Bundle**: No code splitting - all dependencies bundled together
- **Aliases**: Path aliases for `@codemirror/state` and `@codemirror/view` to ensure consistent versions

**Build Process**:
1. Vite reads all source files from `frontend/src/`
2. Resolves npm dependencies (@codemirror packages)
3. Bundles everything into two formats:
   - ES module (`project-notes-frontend.es.js`) - 1.0 MB
   - UMD (`project-notes-frontend.umd.js`) - 679 KB
4. Outputs to `static/dist/` where Go server can serve them
5. Templates load the ES module version via `<script type="module">`

**Development Workflow**:
```bash
cd frontend
npm run build          # Build for production
npm run build -- --watch  # Watch mode for development
```

The Go server does not need to be restarted after frontend builds - simply refresh the browser.

## Key Implementation Details

### Front Matter Management

The system automatically manages front matter when saving notes:
- `title`: Auto-generated from filename if missing (converts hyphens to spaces, title-cases)
- `date`: Set to creation date for new files, preserved for existing files
- `last_modified`: Always updated to current timestamp on save (format: `DD-MM-YYYY:HH:MM`)
- `tags`: Preserved from user input; defaults to `["default"]` for new notes

Front matter extraction happens in two places:
- `indexer.ExtractFrontMatterAndBody()` - For file paths
- `indexer.ExtractFrontMatterAndBodyFromReader()` - For `io.Reader` (used when parsing form content)

### Indexing and Search

The indexer maintains two data structures:
- `tags map[string][]string` - Maps tags to file paths for tag-based lookup
- `docs map[string]*Document` - Stores full document metadata for rich search

Re-indexing happens:
- On server startup
- When files are created/modified/deleted (via watcher with 200ms debounce)
- After POST/DELETE/MOVE operations (background goroutine)

Rich search supports multiple query formats:
- General terms: Search across title, tags, path, and body (AND logic)
- `tag:value` - Filter by specific tag (case-insensitive)
- `title:value` - Filter by title content
- `path:value` - Filter by file path
- Quoted phrases: `"exact phrase"` preserves spaces
- Results are scored and ranked by relevance (title matches score highest)

### REST API (v1)

The application includes a full REST API for programmatic access:

**Implementation**: `internal/api/rest_handler.go`

**Endpoints**:
- `GET /api/v1/notes` - List all notes with metadata (JSON)
- `GET /api/v1/notes/{path}` - Get a specific note (JSON or Markdown based on Accept header)
- `PUT /api/v1/notes/{path}` - Create or update a note (accepts JSON or raw Markdown)
- `DELETE /api/v1/notes/{path}` - Delete a note

**Content Negotiation**:
- `Accept: application/json` → Returns JSON with full metadata
- `Accept: text/markdown` → Returns raw Markdown content
- `Content-Type: application/json` → Accepts structured JSON request
- `Content-Type: text/markdown` → Accepts raw Markdown body

**Key Features**:
- Automatic front matter generation for new notes
- Front matter update (last_modified) on PUT operations
- Background re-indexing after modifications
- Path validation (same security as HTML endpoints)
- Supports nested folders (creates parent directories automatically)

**Documentation**: See `API.md` for full REST API documentation with examples.

### Search Modal

A modern command-palette style search modal is available:

**Implementation**: `frontend/src/search.js`

**Features**:
- Keyboard shortcut: `Ctrl/Cmd+K` to open anywhere
- Real-time search with 300ms debounce
- Keyboard navigation: `↑`/`↓` to navigate, `Enter` to open, `Esc` to close
- Highlighting of search terms in results
- Uses existing search API (`/api/search`)
- Displays results with icons, titles, paths, snippets, tags, and dates

**Styling**: Custom styles in `static/theme.css` with Material Darker theme integration.

### Theme and Font Customization

**Implementation**: `frontend/src/theme-manager.js` and `frontend/src/font-manager.js`

The application supports extensive UI customization:

#### Themes
8 dark themes available via Settings (⚙️ icon):
- **Material Dark** (default) - Material Design inspired
- **Monokai** - Classic Monokai colors
- **Dracula** - Popular purple-tinted theme
- **One Dark** - Atom/VS Code inspired
- **Solarized Dark** - Precision colors by Ethan Schoonover
- **Nord** - Arctic, north-bluish color palette
- **Catppuccin** - Soothing pastel theme
- **Everforest** - Comfortable greenish theme

Themes are applied via CSS custom properties and persist in localStorage.

#### Fonts
8 font options with 4 size presets (small, medium, large, extra-large):
- JetBrains Mono (default)
- Fira Code
- Inter
- IBM Plex Mono
- Source Code Pro
- Cascadia Code
- Roboto Mono
- Ubuntu Mono

Font settings apply to both the editor and preview pane.

### Vim Mode

**Implementation**: `frontend/src/vim-mode-manager.js` using `@replit/codemirror-vim`

Optional Vim keybindings for power users:
- **Enable/Disable**: Toggle via Settings (⚙️ icon)
- **Full Vim Support**: hjkl navigation, visual mode, operators, text objects
- **Mode Indicator**: Shows current Vim mode (Normal/Insert/Visual) in editor
- **Persistence**: Vim mode preference saved to localStorage
- **CodeMirror Integration**: Native Vim extension with excellent compatibility

Vim mode users get full modal editing while maintaining CodeMirror features like syntax highlighting and auto-save.

### Keyboard Shortcuts

**Implementation**: `frontend/src/keyboard-shortcuts.js`

The application provides 10+ global keyboard shortcuts for efficient navigation:

**Essential Shortcuts**:
- `Ctrl/Cmd+D` - Create or open today's daily note
- `Ctrl/Cmd+K` - Open search modal
- `Ctrl/Cmd+S` - Save current note (also triggers auto-save)
- `Ctrl/Cmd+B` - Toggle sidebar visibility
- `Ctrl/Cmd+/` - Show keyboard shortcuts help modal

**Editor Shortcuts**:
- `Tab` - Indent (when in editor)
- `Shift+Tab` - Outdent (when in editor)
- `Ctrl/Cmd+Enter` - Save note (alternative to Cmd+S)

**Navigation**:
- `↑`/`↓` - Navigate search results or command palette
- `Enter` - Select/confirm action
- `Esc` - Close modals, cancel actions, clear search

All shortcuts are non-blocking and work across the application. The shortcuts help modal (triggered by `Ctrl/Cmd+/`) provides a quick reference guide.

For complete documentation, see `docs/KEYBOARD_SHORTCUTS.md`.

### Security Considerations

File path validation in `handler.go` and `rest_handler.go`:
- `filepath.Clean()` to normalize paths
- Reject paths starting with `..` or absolute paths (directory traversal prevention)
- Enforce `.md` extension for notes
- Use `filepath.Join()` to construct safe paths within notes directory
- DOMPurify sanitizes Markdown-rendered HTML to prevent XSS attacks

**REST API Security**:
- No authentication currently implemented
- Recommend using reverse proxy (nginx, Caddy) with auth for public exposure
- CORS not configured (same-origin only)
- No rate limiting (add middleware if needed)

### Template System

Templates are pre-parsed at startup. The API handler returns HTML fragments that htmx inserts into the page. Out-of-band swaps update the file tree sidebar without full page reload.

### Concurrency

- Indexer uses `sync.RWMutex` for thread-safe access (read locks for searches, write locks for re-indexing)
- Re-indexing after saves/deletes/moves happens in background goroutines to avoid blocking HTTP responses
- Watcher runs in separate goroutine with proper context cancellation
- Server shutdown uses 5-second graceful shutdown timeout with context

### File Organization

The application supports hierarchical note organization:
- Notes can be organized in subdirectories within the `notes/` directory
- The file tree displays folders and files in a hierarchical view
- Folders are displayed before files, both sorted alphabetically (case-insensitive)
- API endpoints for folder creation (`/api/folders/create`) and file moving (`/api/files/move`)
- Watcher recursively monitors all subdirectories for changes

### CodeMirror 6 Editor Implementation

The editor is implemented in `frontend/src/editor.js` with two main classes:

#### MarkdownEditor Class
Manages the CodeMirror 6 instance and its interactions:

**Initialization**:
```javascript
EditorState.create({
    doc: content,
    extensions: [
        basicSetup,              // Line numbers, search, fold gutter
        markdown(),              // Markdown syntax support
        oneDark,                 // One Dark theme
        keymap.of([indentWithTab]),
        EditorView.updateListener.of(...),  // Preview & auto-save
        keymap.of([{ key: "Mod-s", run: saveFunction }])
    ]
});
```

**Key Features**:
- **Live Preview**: Updates preview pane with 150ms debounce on editor changes
- **Auto-Save**: Triggers form submission after 2 seconds of inactivity
- **Scroll Sync**: Bidirectional scroll synchronization between editor and preview (50ms debounce)
- **Front Matter Stripping**: Removes YAML front matter from preview rendering
- **View Modes**: Three modes (split/editor-only/preview-only) saved to localStorage
- **Height Management**: Dynamic height calculation (`window.innerHeight - 180px`) with resize handling
- **Cleanup**: Proper destruction of editor instances to prevent memory leaks

**Integration**:
- Replaces the hidden textarea element
- HTMX events trigger editor initialization (`htmx:afterSwap`)
- Form submission uses `requestSubmit()` to trigger HTMX POST

#### SlashCommands Class
Provides command palette for quick Markdown insertion:

**Trigger**: Type `/` at the beginning of a line to open the palette

**Implementation**:
- Monitors editor state changes for `/` character
- Filters commands in real-time as user types
- Positions palette dynamically using CodeMirror's `coordsAtPos()`
- Keyboard navigation with arrow keys, Enter/Tab to select
- Inserts Markdown text using CodeMirror transactions
- 13 built-in commands with text templates

**UI/UX**:
- Styled palette with gradient selection indicator
- Smooth animations and transitions
- Accessible keyboard navigation
- Auto-closes on selection or Escape key

### Slash Commands

The editor includes a slash command system integrated with CodeMirror 6:
- Type `/` at the start of a line to trigger the command palette
- Available commands (14 total):
  - **Headings**: h1, h2, h3 - Insert Markdown headers
  - **Formatting**: bold, italic, code - Text formatting
  - **Blocks**: codeblock, quote, hr, table - Block-level elements
  - **Lists**: list - Unordered list
  - **Dynamic**: date - Insert current date in French format (DD/MM/YYYY)
  - **Links**:
    - `link` - Insert standard Markdown link `[texte](url)`
    - `ilink` - Open internal note linking modal (see Note Linking below)
- Navigate with Arrow Up/Down, select with Enter/Tab, cancel with Escape
- Commands are filtered in real-time as you type after the `/`
- The palette is positioned dynamically near the cursor using CodeMirror coordinates
- Implementation in `frontend/src/editor.js` with the `SlashCommands` class
- Styled command palette with gradient selection indicator

### Note Linking

**Implementation**: `frontend/src/link-inserter.js`

The note linking system allows users to create Markdown links between notes without leaving the editor:

**Activation**: Type `/ilink` (internal link) in the editor and select the command from the slash palette

**Features**:
- **Fuzzy Search**: Real-time search across all notes with 200ms debounce
- **Keyboard Navigation**: Navigate with ↑/↓, select with Enter, cancel with Esc
- **Search Integration**: Reuses existing `/api/search` endpoint (no new backend code)
- **Rich Results**: Shows note title, path, tags, and metadata
- **Instant Insertion**: Inserts `[Note Title](path/to/note.md)` format at cursor position

**Architecture**:
- `LinkInserter` class manages the search modal and selection
- Opens via `SlashCommands.openLinkInserter()` when `/ilink` is triggered
- Uses HTMX search API for consistency
- Modal styled to match `SearchModal` design language

**Workflow**:
1. User types `/ilink` → slash palette appears
2. User selects "ilink" → modal opens with search input
3. User types search query → fuzzy search filters notes
4. User selects note (Enter/click) → Markdown link inserted
5. Modal closes → editor regains focus at end of inserted link

**Standard Links**: For external URLs, use `/link` to insert the standard Markdown template `[texte](url)`

**Link Format**: Links are inserted as HTML with HTMX attributes:
```html
<a href="#" hx-get="/api/notes/path/to/note.md" hx-target="#editor-container" hx-swap="innerHTML">Note Title</a>
```

This format:
- **Clickable in preview**: Links open the note directly in the editor when clicked
- **HTMX-powered**: Uses existing HTMX infrastructure (no new backend code)
- **Inline HTML**: Marked.js renders the HTML as-is, DOMPurify sanitizes it, HTMX processes it
- **Editable**: Plain HTML in the source, can be manually edited if needed

**Note**: This format is specific to this application. For compatibility with other Markdown tools, use standard Markdown links with `/link` command.

## Frontend Libraries

The application uses a mix of npm packages (for the editor) and CDN-loaded libraries (for utilities):

### NPM Packages (Built with Vite)
Managed in `frontend/package.json`:
- **@codemirror/basic-setup (^0.20.0)**: Base editor functionality (line numbers, search, etc.)
- **@codemirror/lang-markdown (^6.5.0)**: Markdown language support and syntax highlighting
- **@codemirror/state (^6.5.2)**: Editor state management
- **@codemirror/view (^6.38.6)**: Editor view layer and rendering
- **@codemirror/theme-one-dark (^6.1.3)**: Dark theme for CodeMirror
- **@replit/codemirror-vim (^6.2.2)**: Vim mode integration for CodeMirror
- **vite (^7.2.2)**: Build tool for bundling frontend modules

### CDN Libraries
Loaded in `templates/index.html`:
- **htmx (1.9.10)**: AJAX interactions and dynamic content loading
- **marked.js**: Markdown to HTML conversion for preview
- **DOMPurify**: HTML sanitization to prevent XSS attacks
- **Highlight.js (11.9.0)**: Syntax highlighting for code blocks in preview with Atom One Dark theme

### Styling
- **8 Dark Themes**: Switchable themes in `static/theme.css`
  - Material Dark, Monokai, Dracula, One Dark, Solarized, Nord, Catppuccin, Everforest
- **Color System**: CSS custom properties for consistent theming
  - Background colors: `--bg-primary`, `--bg-secondary`, `--bg-tertiary`, `--bg-elevated`
  - Text colors: `--text-primary`, `--text-secondary`, `--text-muted`
  - Accent colors: `--accent-blue`, `--accent-violet`
- **Font Customization**: 8 font families with 4 size presets
- **No CSS Framework**: All styles hand-crafted with CSS Grid and Flexbox
- **Responsive Design**: Adaptive layout for different screen sizes
- **Custom Scrollbars**: Styled scrollbars matching the current theme

### Build Output
The Vite build process produces:
- `static/dist/project-notes-frontend.es.js` - ES module format (1.0 MB, includes all CodeMirror 6 dependencies)
- `static/dist/project-notes-frontend.umd.js` - UMD format (679 KB, legacy compatibility)

## Project Structure

```
project-notes/
├── cmd/
│   └── server/
│       └── main.go              # Server entry point
├── internal/
│   ├── api/
│   │   ├── handler.go           # HTTP handlers for CRUD operations
│   │   ├── rest_handler.go      # REST API v1 endpoints
│   │   ├── daily_notes.go       # Daily notes functionality
│   │   └── favorites.go         # Favorites management
│   ├── indexer/
│   │   ├── indexer.go           # Note indexing and search
│   │   └── indexer_test.go      # Indexer tests
│   └── watcher/
│       └── watcher.go           # Filesystem watcher with fsnotify
├── frontend/                    # Frontend build system
│   ├── src/
│   │   ├── main.js              # Entry point - imports all modules
│   │   ├── editor.js            # CodeMirror 6 editor with slash commands
│   │   ├── vim-mode-manager.js  # Vim mode integration
│   │   ├── search.js            # Search modal (Ctrl/Cmd+K)
│   │   ├── file-tree.js         # Drag-and-drop file tree
│   │   ├── favorites.js         # Favorites system
│   │   ├── daily-notes.js       # Daily notes and calendar widget
│   │   ├── keyboard-shortcuts.js # Global keyboard shortcuts
│   │   ├── theme-manager.js     # Theme switching
│   │   ├── font-manager.js      # Font customization
│   │   └── ui.js                # Sidebar toggle
│   ├── package.json             # NPM dependencies
│   ├── package-lock.json
│   └── vite.config.js           # Vite build configuration
├── static/
│   ├── dist/                    # Compiled frontend (generated)
│   │   ├── project-notes-frontend.es.js
│   │   └── project-notes-frontend.umd.js
│   └── theme.css                # Material Darker theme
├── templates/
│   ├── index.html               # Main page layout
│   ├── editor.html              # Editor component
│   ├── file-tree.html           # File tree sidebar
│   ├── search-results.html      # Search results
│   └── new-note-prompt.html     # New note modal
├── notes/                       # Note storage directory
│   ├── *.md                     # Markdown files with YAML front matter
│   ├── daily/                   # Daily notes (YYYY-MM-DD.md)
│   ├── .favorites.json          # Favorites list (auto-generated)
│   └── daily-note-template.md   # Optional daily note template
├── docs/                        # Documentation
│   ├── KEYBOARD_SHORTCUTS.md    # Keyboard shortcuts reference
│   ├── DAILY_NOTES.md           # Daily notes guide
│   ├── USAGE_GUIDE.md           # Complete usage guide
│   └── FREEBSD_BUILD.md         # FreeBSD build guide
├── go.mod                       # Go dependencies
├── go.sum
├── API.md                       # REST API documentation
└── CLAUDE.md                    # This file
```

### Key Files to Edit

**Backend Development**:
- `cmd/server/main.go` - Server initialization and routing
- `internal/api/handler.go` - Main HTML endpoints and request handling
- `internal/api/rest_handler.go` - REST API v1 endpoints
- `internal/api/daily_notes.go` - Daily notes and calendar functionality
- `internal/api/favorites.go` - Favorites management
- `internal/indexer/indexer.go` - Search and indexing logic
- `internal/watcher/watcher.go` - Filesystem monitoring

**Frontend Development**:
- `frontend/src/editor.js` - CodeMirror editor, preview, slash commands
- `frontend/src/vim-mode-manager.js` - Vim mode integration
- `frontend/src/search.js` - Search modal functionality
- `frontend/src/link-inserter.js` - Note linking modal for `/link` command
- `frontend/src/file-tree.js` - File tree interactions and drag-and-drop
- `frontend/src/favorites.js` - Favorites system
- `frontend/src/daily-notes.js` - Daily notes creation and calendar widget
- `frontend/src/keyboard-shortcuts.js` - Global keyboard shortcuts
- `frontend/src/theme-manager.js` - Theme switching logic
- `frontend/src/font-manager.js` - Font customization logic
- `frontend/src/ui.js` - UI utilities (sidebar toggle)
- `static/theme.css` - Styling and theming (8 themes)
- `templates/*.html` - HTML templates (Go template syntax)

**Configuration**:
- `frontend/vite.config.js` - Frontend build configuration
- `frontend/package.json` - NPM dependencies and scripts
- `go.mod` - Go dependencies

### Important Notes

1. **Frontend builds are required**: The application will not work without compiled JavaScript in `static/dist/`
2. **No hot reload for frontend**: Changes to `frontend/src/` require running `npm run build` and refreshing the browser
3. **Backend changes**: Require restarting the Go server (`go run ./cmd/server`)
4. **Template changes**: Require restarting the Go server (templates are pre-parsed at startup)
5. **CSS changes**: Only require browser refresh (loaded via `<link>` tag)
6. **Note changes**: Automatically detected by filesystem watcher, trigger re-indexing