fix: resolve editor, batch conversion, and startup performance issues

- Remove popout preview button (HTML, JS, CSS)
- Fix Save/Save As flow for new untitled files
- Fix batch conversion menu items (wire show-batch-converter IPC)
- Add universal-convert-batch IPC handler for batch file conversion
- Lazy-load mermaid, pdfjs-dist, sidebar panels, command palette
- Switch highlight.js CSS from CDN to local
- Defer CodeMirror language extensions until first use
- Add show:false + ready-to-show for faster perceived startup
- Install mermaid as local dependency (remove CDN script tag)

.gitignore

@@ -33,4 +33,4 @@ pdf\ modal.png
 # Claude/AI development files
 .claude/
 CLAUDE.md
-agents.md
+agents.mdcoverage/

UPDATES.md

@@ -1,5 +1,56 @@
 # PanConverter - Updates & Changelog
 
+## Version 4.0.0 (2026-03-04)
+
+### Major Changes
+- **CodeMirror 6 Editor** — Replaced textarea with CodeMirror 6 featuring syntax highlighting, code folding, bracket matching, multiple cursors, and auto-indent
+- **Sidebar Panel System** — Collapsible sidebar with File Explorer, Git, Snippets, and Templates panels
+- **Command Palette** — Ctrl+Shift+P to search and execute all app actions
+- **Code Execution (REPL)** — Run JavaScript, Python, and Bash code blocks directly from the preview
+
+### New Features
+- Print Preview dialog with paper size, orientation, margins, scale, and page range controls
+- Image paste from clipboard and drag-drop support with auto-save to assets folder
+- Document templates library (10 templates: blog post, meeting notes, tech spec, changelog, README, project plan, API docs, tutorial, release notes, comparison)
+- Markdown extensions: footnotes, admonitions (note/warning/tip/danger/info), and [[toc]] table of contents
+- PlantUML diagram rendering alongside Mermaid
+- Welcome tab with onboarding and "What's New" feature showcase
+- System spell checking with context menu suggestions and dictionary support
+- Enhanced status bar with word count, character count, line/column, encoding, and language mode
+- Grouped toolbar with visual section separators
+- Breadcrumb bar showing current file path
+
+### New Export/Import Formats
+- Reveal.js slides (.html)
+- Beamer slides (.pdf)
+- Confluence/Jira wiki markup (.txt)
+- MOBI e-books (via Calibre)
+- Developer formats: JSON, YAML, XML, TOML
+
+### Security
+- Content Security Policy (CSP) meta tag
+- File size validation (50MB limit)
+- Error message sanitization (stripped file paths)
+- Conversion rate limiting (2-second debounce)
+
+### Dependencies Updated
+- marked: 16.x to 17.x (with marked-highlight extension)
+- pdfjs-dist: 3.x to 5.x (new worker model)
+- html2pdf.js: 0.10 to 0.14
+- pdfkit: 0.14 to 0.17
+- dompurify, docx, and others updated to latest
+
+### Testing
+- 80 tests across 7 test suites
+- New tests for sidebar manager, command palette, print preview, markdown extensions, and utility functions
+
+### Breaking Changes
+- Editor is now CodeMirror 6 (replaces textarea)
+- marked API changed to use marked.use() instead of marked.setOptions()
+- pdfjs-dist upgraded to v5 with new worker model
+
+---
+
 ## Version 2.1.0 (December 14, 2025)
 
 ### 🎨 UI/UX Improvements

eslint.config.js

@@ -38,10 +38,30 @@ module.exports = [
         document: 'readonly',
         localStorage: 'readonly',
         alert: 'readonly',
+        prompt: 'readonly',
+        confirm: 'readonly',
         Event: 'readonly',
         CustomEvent: 'readonly',
         HTMLElement: 'readonly',
         MutationObserver: 'readonly',
+        TextEncoder: 'readonly',
+        FileReader: 'readonly',
+        requestAnimationFrame: 'readonly',
+        cancelAnimationFrame: 'readonly',
+        navigator: 'readonly',
+        location: 'readonly',
+        fetch: 'readonly',
+        URL: 'readonly',
+        Blob: 'readonly',
+        Image: 'readonly',
+        DragEvent: 'readonly',
+        ClipboardEvent: 'readonly',
+        KeyboardEvent: 'readonly',
+        MouseEvent: 'readonly',
+        NodeList: 'readonly',
+        HTMLInputElement: 'readonly',
+        HTMLTextAreaElement: 'readonly',
+        getComputedStyle: 'readonly',
         // Electron
         electronAPI: 'readonly',
         // Libraries
@@ -49,6 +69,8 @@ module.exports = [
         DOMPurify: 'readonly',
         hljs: 'readonly',
         mermaid: 'readonly',
+        // Node.js global object
+        global: 'writable',
         // Jest
         jest: 'readonly',
         describe: 'readonly',

jest.config.js

@@ -20,16 +20,18 @@ module.exports = {
   collectCoverageFrom: [
     'src/**/*.js',
     '!src/main.js', // Main process needs electron-mock
+    '!src/renderer.js', // Large renderer file with duplicate declarations
+    '!src/preload.js', // Electron preload requires contextBridge
     '!**/node_modules/**'
   ],
 
-  // Coverage thresholds (start low, increase over time)
+  // Coverage thresholds (raised with expanded test suite)
   coverageThreshold: {
     global: {
       branches: 10,
-      functions: 10,
-      lines: 10,
-      statements: 10
+      functions: 15,
+      lines: 15,
+      statements: 15
     }
   },
 

package.json

@@ -1,6 +1,6 @@
 {
   "name": "markdown-converter",
-  "version": "3.0.0",
+  "version": "4.0.0",
   "description": "Professional Markdown editor and universal file converter with PDF editing, batch processing, and syntax highlighting",
   "main": "src/main.js",
   "scripts": {
@@ -52,19 +52,37 @@
     "sharp": "^0.34.3"
   },
   "dependencies": {
+    "@codemirror/autocomplete": "^6.20.1",
+    "@codemirror/commands": "^6.10.2",
+    "@codemirror/lang-css": "^6.3.1",
+    "@codemirror/lang-html": "^6.4.11",
+    "@codemirror/lang-javascript": "^6.2.5",
+    "@codemirror/lang-json": "^6.0.2",
+    "@codemirror/lang-markdown": "^6.5.0",
+    "@codemirror/lang-python": "^6.2.1",
+    "@codemirror/language": "^6.12.2",
+    "@codemirror/lint": "^6.9.5",
+    "@codemirror/search": "^6.6.0",
+    "@codemirror/state": "^6.5.4",
+    "@codemirror/theme-one-dark": "^6.1.3",
+    "@codemirror/view": "^6.39.16",
     "codemirror": "^6.0.2",
     "core-util-is": "^1.0.3",
-    "docx": "^9.5.1",
+    "docx": "^9.6.0",
     "docx4js": "^3.3.0",
-    "dompurify": "^3.2.6",
+    "dompurify": "^3.3.1",
     "electron-store": "^10.1.0",
     "highlight.js": "^11.11.1",
-    "html2pdf.js": "^0.10.1",
-    "marked": "^16.2.1",
+    "html2pdf.js": "^0.14.0",
+    "marked": "^17.0.3",
+    "marked-footnote": "^1.4.0",
+    "marked-highlight": "^2.2.3",
+    "mermaid": "^11.12.3",
     "pdf-lib": "^1.17.1",
-    "pdfjs-dist": "^3.11.174",
-    "pdfkit": "^0.14.0",
+    "pdfjs-dist": "^5.5.207",
+    "pdfkit": "^0.17.2",
     "pizzip": "^3.2.0",
+    "simple-git": "^3.32.3",
     "tslib": "^2.8.1",
     "xlsx": "^0.18.5"
   },

src/command-palette.js

@@ -0,0 +1,109 @@
+class CommandPalette {
+    constructor() {
+        this.overlay = document.getElementById('command-palette-overlay');
+        this.input = document.getElementById('command-palette-input');
+        this.results = document.getElementById('command-palette-results');
+        this.commands = [];
+        this.selectedIndex = 0;
+        this.filteredCommands = [];
+        this.setupEventListeners();
+    }
+
+    register(label, shortcut, action) {
+        this.commands.push({ label, shortcut, action });
+    }
+
+    open() {
+        this.overlay.classList.remove('hidden');
+        this.input.value = '';
+        this.input.focus();
+        this.selectedIndex = 0;
+        this.renderResults('');
+    }
+
+    close() {
+        this.overlay.classList.add('hidden');
+    }
+
+    isOpen() {
+        return !this.overlay.classList.contains('hidden');
+    }
+
+    setupEventListeners() {
+        this.input.addEventListener('input', () => {
+            this.selectedIndex = 0;
+            this.renderResults(this.input.value);
+        });
+
+        this.overlay.addEventListener('click', (e) => {
+            if (e.target === this.overlay) this.close();
+        });
+
+        this.input.addEventListener('keydown', (e) => {
+            if (e.key === 'Escape') {
+                e.preventDefault();
+                this.close();
+            } else if (e.key === 'Enter') {
+                e.preventDefault();
+                this.executeSelected();
+            } else if (e.key === 'ArrowDown') {
+                e.preventDefault();
+                this.selectedIndex = Math.min(this.selectedIndex + 1, this.filteredCommands.length - 1);
+                this.updateSelection();
+            } else if (e.key === 'ArrowUp') {
+                e.preventDefault();
+                this.selectedIndex = Math.max(this.selectedIndex - 1, 0);
+                this.updateSelection();
+            }
+        });
+    }
+
+    renderResults(query) {
+        this.filteredCommands = query
+            ? this.commands.filter(cmd => cmd.label.toLowerCase().includes(query.toLowerCase()))
+            : [...this.commands];
+
+        this.results.innerHTML = this.filteredCommands.map((cmd, i) => `
+            <div class="command-item ${i === this.selectedIndex ? 'selected' : ''}" data-index="${i}">
+                <span class="command-label">${this.highlightMatch(cmd.label, query)}</span>
+                ${cmd.shortcut ? `<span class="command-shortcut">${cmd.shortcut}</span>` : ''}
+            </div>
+        `).join('');
+
+        this.results.querySelectorAll('.command-item').forEach((el) => {
+            el.addEventListener('click', () => {
+                const idx = parseInt(el.dataset.index);
+                this.filteredCommands[idx].action();
+                this.close();
+            });
+            el.addEventListener('mouseenter', () => {
+                this.selectedIndex = parseInt(el.dataset.index);
+                this.updateSelection();
+            });
+        });
+    }
+
+    highlightMatch(text, query) {
+        if (!query) return text;
+        const regex = new RegExp(`(${query.replace(/[.*+?^${}()|[\]\\]/g, '\\$&')})`, 'gi');
+        return text.replace(regex, '<strong>$1</strong>');
+    }
+
+    updateSelection() {
+        this.results.querySelectorAll('.command-item').forEach((el, i) => {
+            el.classList.toggle('selected', i === this.selectedIndex);
+        });
+        // Scroll selected into view
+        const selected = this.results.querySelector('.command-item.selected');
+        if (selected) selected.scrollIntoView({ block: 'nearest' });
+    }
+
+    executeSelected() {
+        if (this.filteredCommands[this.selectedIndex]) {
+            this.filteredCommands[this.selectedIndex].action();
+            this.close();
+        }
+    }
+}
+
+module.exports = { CommandPalette };

src/editor/codemirror-setup.js

@@ -0,0 +1,123 @@
+// CodeMirror 6 wrapper module
+// Provides createEditor() and getLanguageExtension() for the rest of the app.
+
+const {
+  EditorView,
+  keymap,
+  lineNumbers,
+  highlightActiveLine,
+  drawSelection,
+} = require('@codemirror/view');
+const { EditorState } = require('@codemirror/state');
+const { markdown, markdownLanguage } = require('@codemirror/lang-markdown');
+// Language extensions loaded lazily on first use
+let _javascript, _html, _css, _json, _python;
+const {
+  defaultKeymap,
+  history,
+  historyKeymap,
+  indentWithTab,
+} = require('@codemirror/commands');
+const {
+  searchKeymap,
+  highlightSelectionMatches,
+} = require('@codemirror/search');
+const {
+  autocompletion,
+  completionKeymap,
+} = require('@codemirror/autocomplete');
+const {
+  bracketMatching,
+  foldGutter,
+  indentOnInput,
+} = require('@codemirror/language');
+const { oneDark } = require('@codemirror/theme-one-dark');
+
+/**
+ * Create a CodeMirror 6 editor instance.
+ *
+ * @param {HTMLElement} parentElement - DOM element to mount the editor in
+ * @param {Object}  options
+ * @param {string}  options.content          - initial document content (default '')
+ * @param {Function} options.onChange        - called with new content string on every doc change
+ * @param {Function} options.onUpdate       - called with the EditorView on every update (selection, doc change, etc.)
+ * @param {boolean} options.isDark           - apply oneDark theme when true (default false)
+ * @param {boolean} options.showLineNumbers  - show line-number gutter (default true)
+ * @returns {EditorView} the created editor view
+ */
+function createEditor(parentElement, options = {}) {
+  const {
+    content = '',
+    onChange = () => {},
+    onUpdate = null,
+    isDark = false,
+    showLineNumbers = true,
+  } = options;
+
+  const extensions = [
+    markdown({ base: markdownLanguage }),
+    history(),
+    drawSelection(),
+    highlightActiveLine(),
+    bracketMatching(),
+    indentOnInput(),
+    highlightSelectionMatches(),
+    autocompletion(),
+    foldGutter(),
+    keymap.of([
+      ...defaultKeymap,
+      ...historyKeymap,
+      ...searchKeymap,
+      ...completionKeymap,
+      indentWithTab,
+    ]),
+    EditorView.updateListener.of((update) => {
+      if (update.docChanged) {
+        onChange(update.state.doc.toString());
+      }
+      if (onUpdate && (update.docChanged || update.selectionSet)) {
+        onUpdate(update.view);
+      }
+    }),
+    EditorView.lineWrapping,
+  ];
+
+  if (showLineNumbers) {
+    extensions.push(lineNumbers());
+  }
+
+  if (isDark) {
+    extensions.push(oneDark);
+  }
+
+  const state = EditorState.create({ doc: content, extensions });
+  const view = new EditorView({ state, parent: parentElement });
+  return view;
+}
+
+/**
+ * Return the appropriate CodeMirror language extension for a given language name.
+ *
+ * Supported values: javascript, js, html, css, json, python, py, markdown.
+ * Falls back to markdown when the language is unrecognised.
+ *
+ * @param {string} lang - language identifier
+ * @returns {Extension} CodeMirror language extension
+ */
+function getLanguageExtension(lang) {
+  const loaders = {
+    javascript: () => { if (!_javascript) _javascript = require('@codemirror/lang-javascript').javascript; return _javascript(); },
+    html: () => { if (!_html) _html = require('@codemirror/lang-html').html; return _html(); },
+    css: () => { if (!_css) _css = require('@codemirror/lang-css').css; return _css(); },
+    json: () => { if (!_json) _json = require('@codemirror/lang-json').json; return _json(); },
+    python: () => { if (!_python) _python = require('@codemirror/lang-python').python; return _python(); },
+    markdown: () => markdown({ base: markdownLanguage }),
+  };
+  loaders.js = loaders.javascript;
+  loaders.py = loaders.python;
+
+  const loader = loaders[lang];
+  return loader ? loader() : markdown({ base: markdownLanguage });
+}
+
+module.exports = { createEditor, getLanguageExtension };

src/index.html

@@ -2,15 +2,16 @@
 <html lang="en">
 <head>
     <meta charset="UTF-8">
+    <meta http-equiv="Content-Security-Policy" content="default-src 'self'; script-src 'self' 'unsafe-inline' 'unsafe-eval' https://cdn.jsdelivr.net; style-src 'self' 'unsafe-inline' https://cdnjs.cloudflare.com; img-src 'self' data: blob: file:; font-src 'self' data:; connect-src 'self' https://www.plantuml.com;">
     <meta name="viewport" content="width=device-width, initial-scale=1.0">
     <title>MarkdownConverter</title>
     <link rel="stylesheet" href="fonts.css">
     <link rel="stylesheet" href="styles.css">
     <link rel="stylesheet" href="styles-modern.css">
     <link rel="stylesheet" href="styles-concreteinfo.css">
-    <!-- Load external resources asynchronously -->
-    <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/highlight.js/11.9.0/styles/default.min.css" media="print" onload="this.media='all'">
-    <script defer src="https://cdn.jsdelivr.net/npm/mermaid@10/dist/mermaid.min.js"></script>
+    <link rel="stylesheet" href="styles-sidebar.css">
+    <link rel="stylesheet" href="styles-welcome.css">
+    <link rel="stylesheet" href="../node_modules/highlight.js/styles/default.css">
 </head>
 <body>
     <div class="container">
@@ -21,7 +22,7 @@
                 <span class="app-title">MarkdownConverter</span>
             </div>
             <div class="app-header-right">
-                <span class="app-version">v3.0.0</span>
+                <span class="app-version">v4.0.0</span>
             </div>
         </div>
         <div class="tab-bar" id="tab-bar">
@@ -32,105 +33,122 @@
             <button class="new-tab-button" id="new-tab-btn" title="New tab">+</button>
         </div>
         <div class="toolbar">
-            <button id="btn-bold" title="Bold">
-                <svg width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2">
-                    <path d="M6 4h8a4 4 0 0 1 4 4 4 4 0 0 1-4 4H6z"></path>
-                    <path d="M6 12h9a4 4 0 0 1 4 4 4 4 0 0 1-4 4H6z"></path>
-                </svg>
-            </button>
-            <button id="btn-italic" title="Italic">
-                <svg width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2">
-                    <line x1="19" y1="4" x2="10" y2="4"></line>
-                    <line x1="14" y1="20" x2="5" y2="20"></line>
-                    <line x1="15" y1="4" x2="9" y2="20"></line>
-                </svg>
-            </button>
-            <button id="btn-heading" title="Heading">
-                <svg width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2">
-                    <polyline points="4 7 4 4 20 4 20 7"></polyline>
-                    <line x1="9" y1="20" x2="15" y2="20"></line>
-                    <line x1="12" y1="4" x2="12" y2="20"></line>
-                </svg>
-            </button>
-            <button id="btn-link" title="Link">
-                <svg width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2">
-                    <path d="M10 13a5 5 0 0 0 7.54.54l3-3a5 5 0 0 0-7.07-7.07l-1.72 1.71"></path>
-                    <path d="M14 11a5 5 0 0 0-7.54-.54l-3 3a5 5 0 0 0 7.07 7.07l1.71-1.71"></path>
-                </svg>
-            </button>
-            <button id="btn-code" title="Code">
-                <svg width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2">
-                    <polyline points="16 18 22 12 16 6"></polyline>
-                    <polyline points="8 6 2 12 8 18"></polyline>
-                </svg>
-            </button>
-            <button id="btn-list" title="List">
-                <svg width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2">
-                    <line x1="8" y1="6" x2="21" y2="6"></line>
-                    <line x1="8" y1="12" x2="21" y2="12"></line>
-                    <line x1="8" y1="18" x2="21" y2="18"></line>
-                    <line x1="3" y1="6" x2="3.01" y2="6"></line>
-                    <line x1="3" y1="12" x2="3.01" y2="12"></line>
-                    <line x1="3" y1="18" x2="3.01" y2="18"></line>
-                </svg>
-            </button>
-            <button id="btn-quote" title="Quote">
-                <svg width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2">
-                    <path d="M3 21c3 0 7-1 7-8V5c0-1.25-.756-2.017-2-2H4c-1.25 0-2 .75-2 1.972V11c0 1.25.75 2 2 2 1 0 1 0 1 1v1c0 1-1 2-2 2s-1 .008-1 1.031V20c0 1 0 1 1 1z"></path>
-                    <path d="M15 21c3 0 7-1 7-8V5c0-1.25-.757-2.017-2-2h-4c-1.25 0-2 .75-2 1.972V11c0 1.25.75 2 2 2h.75c0 2.25.25 4-2.75 4v3c0 1 0 1 1 1z"></path>
-                </svg>
-            </button>
-            <button id="btn-table" title="Insert Table">
-                <svg width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2">
-                    <rect x="3" y="3" width="18" height="18" rx="2" ry="2"></rect>
-                    <line x1="3" y1="9" x2="21" y2="9"></line>
-                    <line x1="3" y1="15" x2="21" y2="15"></line>
-                    <line x1="9" y1="3" x2="9" y2="21"></line>
-                    <line x1="15" y1="3" x2="15" y2="21"></line>
-                </svg>
-            </button>
-            <button id="btn-strikethrough" title="Strikethrough">
-                <svg width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2">
-                    <path d="M16 4H9a3 3 0 0 0-2.83 4"></path>
-                    <path d="M14 12a4 4 0 0 1 0 8H6"></path>
-                    <line x1="4" y1="12" x2="20" y2="12"></line>
-                </svg>
-            </button>
-            <button id="btn-code-block" title="Code Block">
-                <svg width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2">
-                    <rect x="2" y="6" width="20" height="12" rx="2"></rect>
-                    <path d="m10 10-2 2 2 2"></path>
-                    <path d="m14 10 2 2-2 2"></path>
-                </svg>
-            </button>
-            <button id="btn-horizontal-rule" title="Horizontal Rule">
-                <svg width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2">
-                    <line x1="3" y1="12" x2="21" y2="12"></line>
-                    <line x1="3" y1="6" x2="21" y2="6"></line>
-                    <line x1="3" y1="18" x2="21" y2="18"></line>
-                </svg>
-            </button>
+            <div class="toolbar-group">
+                <!-- Format: Bold, Italic, Strikethrough -->
+                <button id="btn-bold" title="Bold (Ctrl+B)">
+                    <svg width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2">
+                        <path d="M6 4h8a4 4 0 0 1 4 4 4 4 0 0 1-4 4H6z"></path>
+                        <path d="M6 12h9a4 4 0 0 1 4 4 4 4 0 0 1-4 4H6z"></path>
+                    </svg>
+                </button>
+                <button id="btn-italic" title="Italic (Ctrl+I)">
+                    <svg width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2">
+                        <line x1="19" y1="4" x2="10" y2="4"></line>
+                        <line x1="14" y1="20" x2="5" y2="20"></line>
+                        <line x1="15" y1="4" x2="9" y2="20"></line>
+                    </svg>
+                </button>
+                <button id="btn-strikethrough" title="Strikethrough">
+                    <svg width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2">
+                        <path d="M16 4H9a3 3 0 0 0-2.83 4"></path>
+                        <path d="M14 12a4 4 0 0 1 0 8H6"></path>
+                        <line x1="4" y1="12" x2="20" y2="12"></line>
+                    </svg>
+                </button>
+            </div>
             <div class="toolbar-separator"></div>
-            <button id="btn-find" title="Find & Replace (Ctrl+F)">
-                <svg width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2">
-                    <circle cx="11" cy="11" r="8"></circle>
-                    <path d="m21 21-4.35-4.35"></path>
-                </svg>
-            </button>
-            <button id="btn-line-numbers" title="Toggle Line Numbers">
-                <svg width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2">
-                    <path d="M3 6h18"></path>
-                    <path d="M3 12h18"></path>
-                    <path d="M3 18h18"></path>
-                </svg>
-            </button>
+            <div class="toolbar-group">
+                <!-- Structure: Heading, List, Quote -->
+                <button id="btn-heading" title="Heading">
+                    <svg width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2">
+                        <polyline points="4 7 4 4 20 4 20 7"></polyline>
+                        <line x1="9" y1="20" x2="15" y2="20"></line>
+                        <line x1="12" y1="4" x2="12" y2="20"></line>
+                    </svg>
+                </button>
+                <button id="btn-list" title="List">
+                    <svg width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2">
+                        <line x1="8" y1="6" x2="21" y2="6"></line>
+                        <line x1="8" y1="12" x2="21" y2="12"></line>
+                        <line x1="8" y1="18" x2="21" y2="18"></line>
+                        <line x1="3" y1="6" x2="3.01" y2="6"></line>
+                        <line x1="3" y1="12" x2="3.01" y2="12"></line>
+                        <line x1="3" y1="18" x2="3.01" y2="18"></line>
+                    </svg>
+                </button>
+                <button id="btn-quote" title="Quote">
+                    <svg width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2">
+                        <path d="M3 21c3 0 7-1 7-8V5c0-1.25-.756-2.017-2-2H4c-1.25 0-2 .75-2 1.972V11c0 1.25.75 2 2 2 1 0 1 0 1 1v1c0 1-1 2-2 2s-1 .008-1 1.031V20c0 1 0 1 1 1z"></path>
+                        <path d="M15 21c3 0 7-1 7-8V5c0-1.25-.757-2.017-2-2h-4c-1.25 0-2 .75-2 1.972V11c0 1.25.75 2 2 2h.75c0 2.25.25 4-2.75 4v3c0 1 0 1 1 1z"></path>
+                    </svg>
+                </button>
+            </div>
             <div class="toolbar-separator"></div>
-            <button id="btn-preview-toggle" title="Toggle Preview">
-                <svg width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2">
-                    <path d="M1 12s4-8 11-8 11 8 11 8-4 8-11 8-11-8-11-8z"></path>
-                    <circle cx="12" cy="12" r="3"></circle>
-                </svg>
-            </button>
+            <div class="toolbar-group">
+                <!-- Insert: Link, Code, Code Block, Table, HR -->
+                <button id="btn-link" title="Link">
+                    <svg width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2">
+                        <path d="M10 13a5 5 0 0 0 7.54.54l3-3a5 5 0 0 0-7.07-7.07l-1.72 1.71"></path>
+                        <path d="M14 11a5 5 0 0 0-7.54-.54l-3 3a5 5 0 0 0 7.07 7.07l1.71-1.71"></path>
+                    </svg>
+                </button>
+                <button id="btn-code" title="Inline Code (Ctrl+`)">
+                    <svg width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2">
+                        <polyline points="16 18 22 12 16 6"></polyline>
+                        <polyline points="8 6 2 12 8 18"></polyline>
+                    </svg>
+                </button>
+                <button id="btn-code-block" title="Code Block">
+                    <svg width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2">
+                        <rect x="2" y="6" width="20" height="12" rx="2"></rect>
+                        <path d="m10 10-2 2 2 2"></path>
+                        <path d="m14 10 2 2-2 2"></path>
+                    </svg>
+                </button>
+                <button id="btn-table" title="Insert Table">
+                    <svg width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2">
+                        <rect x="3" y="3" width="18" height="18" rx="2" ry="2"></rect>
+                        <line x1="3" y1="9" x2="21" y2="9"></line>
+                        <line x1="3" y1="15" x2="21" y2="15"></line>
+                        <line x1="9" y1="3" x2="9" y2="21"></line>
+                        <line x1="15" y1="3" x2="15" y2="21"></line>
+                    </svg>
+                </button>
+                <button id="btn-horizontal-rule" title="Horizontal Rule">
+                    <svg width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2">
+                        <line x1="3" y1="12" x2="21" y2="12"></line>
+                        <line x1="3" y1="6" x2="21" y2="6"></line>
+                        <line x1="3" y1="18" x2="21" y2="18"></line>
+                    </svg>
+                </button>
+            </div>
+            <div class="toolbar-separator"></div>
+            <div class="toolbar-group">
+                <!-- View: Find, Line Numbers, Preview -->
+                <button id="btn-find" title="Find & Replace (Ctrl+F)">
+                    <svg width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2">
+                        <circle cx="11" cy="11" r="8"></circle>
+                        <path d="m21 21-4.35-4.35"></path>
+                    </svg>
+                </button>
+                <button id="btn-line-numbers" title="Toggle Line Numbers">
+                    <svg width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2">
+                        <path d="M3 6h18"></path>
+                        <path d="M3 12h18"></path>
+                        <path d="M3 18h18"></path>
+                    </svg>
+                </button>
+                <button id="btn-preview-toggle" title="Toggle Preview (Ctrl+Shift+P)">
+                    <svg width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2">
+                        <path d="M1 12s4-8 11-8 11 8 11 8-4 8-11 8-11-8-11-8z"></path>
+                        <circle cx="12" cy="12" r="3"></circle>
+                    </svg>
+                </button>
+            </div>
+        </div>
+
+        <div class="breadcrumb-bar" id="breadcrumb-bar">
+            <span class="breadcrumb-path" id="breadcrumb-path">Untitled</span>
         </div>
 
         <!-- Find & Replace Dialog -->
@@ -312,16 +330,86 @@
             </div>
         </div>
 
-        <!-- Command Palette -->
-        <div id="command-palette" class="command-palette hidden">
-            <div class="command-palette-content">
-                <input type="text" id="command-search" placeholder="Type a command..." autofocus>
-                <div id="command-list" class="command-list"></div>
-                <div class="command-palette-footer">
-                    <span>↑↓ Navigate</span>
-                    <span>Enter Execute</span>
-                    <span>Esc Close</span>
+        <!-- Print Preview Dialog -->
+        <div class="export-dialog hidden" id="print-preview-overlay">
+            <div class="export-dialog-content print-preview-dialog">
+                <div class="export-dialog-header">
+                    <h3>Print Preview</h3>
+                    <button id="print-preview-close" title="Close" style="background:none;border:none;color:white;font-size:24px;cursor:pointer;">&times;</button>
                 </div>
+                <div class="print-preview-body">
+                    <div class="print-preview-sidebar">
+                        <div class="print-option-group">
+                            <label>Paper Size</label>
+                            <select id="print-paper-size">
+                                <option value="A3">A3</option>
+                                <option value="A4" selected>A4</option>
+                                <option value="A5">A5</option>
+                                <option value="Letter">Letter</option>
+                                <option value="Legal">Legal</option>
+                                <option value="Tabloid">Tabloid</option>
+                            </select>
+                        </div>
+                        <div class="print-option-group">
+                            <label>Orientation</label>
+                            <select id="print-orientation">
+                                <option value="portrait" selected>Portrait</option>
+                                <option value="landscape">Landscape</option>
+                            </select>
+                        </div>
+                        <div class="print-option-group">
+                            <label>Margins</label>
+                            <select id="print-margins">
+                                <option value="default" selected>Default</option>
+                                <option value="narrow">Narrow</option>
+                                <option value="wide">Wide</option>
+                                <option value="none">None</option>
+                            </select>
+                        </div>
+                        <div class="print-option-group">
+                            <label>Scale</label>
+                            <div class="scale-control">
+                                <input type="range" id="print-scale" min="50" max="200" value="100">
+                                <span id="print-scale-value">100%</span>
+                            </div>
+                        </div>
+                        <div class="print-option-group">
+                            <label class="checkbox-label">
+                                <input type="checkbox" id="print-headers" checked>
+                                Headers &amp; Footers
+                            </label>
+                        </div>
+                        <div class="print-option-group">
+                            <label class="checkbox-label">
+                                <input type="checkbox" id="print-background" checked>
+                                Background Colors
+                            </label>
+                        </div>
+                        <div class="print-option-group">
+                            <label>Pages</label>
+                            <select id="print-pages">
+                                <option value="all" selected>All</option>
+                                <option value="custom">Custom Range</option>
+                            </select>
+                            <input type="text" id="print-page-range" placeholder="e.g., 1-3, 5" class="hidden print-range-input">
+                        </div>
+                        <div class="print-actions">
+                            <button class="btn-primary" id="print-execute">Print</button>
+                            <button class="btn-secondary" id="print-cancel">Cancel</button>
+                        </div>
+                    </div>
+                    <div class="print-preview-content">
+                        <iframe id="print-preview-frame" style="width:100%;height:100%;border:none;background:white;"></iframe>
+                    </div>
+                </div>
+            </div>
+        </div>
+
+        <!-- Command Palette -->
+        <div class="command-palette-overlay hidden" id="command-palette-overlay">
+            <div class="command-palette">
+                <input type="text" class="command-palette-input" id="command-palette-input" placeholder="Type a command..." autocomplete="off">
+                <div class="command-palette-results" id="command-palette-results"></div>
             </div>
         </div>
 
@@ -1293,12 +1381,52 @@
             </div>
         </div>
 
-        <div class="editor-container">
+        <div class="main-content" id="main-content">
+            <!-- Sidebar -->
+            <div class="sidebar collapsed" id="sidebar">
+                <div class="sidebar-icons">
+                    <button class="sidebar-icon" data-panel="explorer" title="File Explorer (Ctrl+Shift+E)">
+                        <svg width="20" height="20" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2">
+                            <path d="M22 19a2 2 0 01-2 2H4a2 2 0 01-2-2V5a2 2 0 012-2h5l2 3h9a2 2 0 012 2z"/>
+                        </svg>
+                    </button>
+                    <button class="sidebar-icon" data-panel="git" title="Git (Ctrl+Shift+G)">
+                        <svg width="20" height="20" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2">
+                            <line x1="6" y1="3" x2="6" y2="15"/>
+                            <circle cx="18" cy="6" r="3"/>
+                            <circle cx="6" cy="6" r="3"/>
+                            <path d="M18 9a9 9 0 01-9 9"/>
+                        </svg>
+                    </button>
+                    <button class="sidebar-icon" data-panel="snippets" title="Snippets (Ctrl+Shift+S)">
+                        <svg width="20" height="20" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2">
+                            <polyline points="16 18 22 12 16 6"/>
+                            <polyline points="8 6 2 12 8 18"/>
+                        </svg>
+                    </button>
+                    <button class="sidebar-icon" data-panel="templates" title="Templates">
+                        <svg width="20" height="20" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2">
+                            <rect x="3" y="3" width="18" height="18" rx="2" ry="2"/>
+                            <line x1="3" y1="9" x2="21" y2="9"/>
+                            <line x1="9" y1="21" x2="9" y2="9"/>
+                        </svg>
+                    </button>
+                </div>
+                <div class="sidebar-panel" id="sidebar-panel">
+                    <div class="sidebar-panel-header">
+                        <span class="sidebar-panel-title"></span>
+                        <button class="sidebar-panel-close" title="Close panel">&times;</button>
+                    </div>
+                    <div class="sidebar-panel-content" id="sidebar-panel-content"></div>
+                </div>
+            </div>
+
+            <!-- Editor Container -->
+            <div class="editor-container">
             <div class="tab-content active" id="tab-content-1" data-tab-id="1">
                 <div id="editor-pane-1" class="pane">
                     <div class="editor-wrapper">
-                        <div id="line-numbers-1" class="line-numbers hidden"></div>
-                        <textarea id="editor-1" class="editor-textarea"></textarea>
+                        <div id="editor-cm-1" class="codemirror-container"></div>
                     </div>
                 </div>
                 <div class="pane-resizer" id="pane-resizer-1" title="Drag to resize"></div>
@@ -1401,11 +1529,38 @@
                     <canvas id="pdf-canvas"></canvas>
                 </div>
             </div>
+            </div>
         </div>
 
-        <div class="status-bar">
-            <span id="status-text">Ready</span>
-            <span id="word-count">Words: 0 | Characters: 0</span>
+        <!-- Bottom Panel (REPL Output) -->
+        <div class="bottom-panel collapsed" id="bottom-panel">
+            <div class="bottom-panel-header">
+                <span class="bottom-panel-title">Output</span>
+                <div class="bottom-panel-actions">
+                    <button class="bottom-panel-btn" id="repl-clear" title="Clear output">Clear</button>
+                    <button class="bottom-panel-btn" id="bottom-panel-toggle" title="Toggle panel">&#x25BC;</button>
+                </div>
+            </div>
+            <div class="bottom-panel-content" id="repl-output"></div>
+        </div>
+
+        <div class="status-bar" id="status-bar">
+            <div class="status-bar-left">
+                <span class="status-item" id="status-text">Ready</span>
+                <span class="status-separator">|</span>
+                <span class="status-item" id="status-file-path" title=""></span>
+            </div>
+            <div class="status-bar-right">
+                <span class="status-item" id="word-count">Words: 0</span>
+                <span class="status-separator">|</span>
+                <span class="status-item" id="char-count">Chars: 0</span>
+                <span class="status-separator">|</span>
+                <span class="status-item" id="line-col">Ln 1, Col 1</span>
+                <span class="status-separator">|</span>
+                <span class="status-item" id="encoding">UTF-8</span>
+                <span class="status-separator">|</span>
+                <span class="status-item" id="language-mode">Markdown</span>
+            </div>
         </div>
     </div>
 

src/main.js

@@ -50,6 +50,48 @@ function safeExecFile(command, args, options = {}) {
   });
 }
 
+// File size validation
+const MAX_FILE_SIZE_MB = 50;
+const MAX_FILE_SIZE = MAX_FILE_SIZE_MB * 1024 * 1024;
+
+// Sanitize error messages to strip absolute file paths
+function sanitizeErrorMessage(message) {
+    if (typeof message !== 'string') return String(message);
+    // Strip absolute Windows paths, keeping only filename
+    return message
+        .replace(/[A-Z]:\\[^\s"']+\\([^\s"'\\]+)/gi, '$1')
+        .replace(/\/[^\s"']+\/([^\s"'/]+)/g, '$1');
+}
+
+// Rate limiter for conversions
+function createRateLimiter(minIntervalMs = 2000) {
+    let lastCall = 0;
+    return function canProceed() {
+        const now = Date.now();
+        if (now - lastCall < minIntervalMs) return false;
+        lastCall = now;
+        return true;
+    };
+}
+const conversionLimiter = createRateLimiter(2000);
+
+// Convert structured data formats to markdown code blocks
+function convertDataToMarkdown(content, format) {
+    switch (format) {
+        case 'json':
+            return '```json\n' + content + '\n```';
+        case 'yaml':
+        case 'yml':
+            return '```yaml\n' + content + '\n```';
+        case 'xml':
+            return '```xml\n' + content + '\n```';
+        case 'toml':
+            return '```toml\n' + content + '\n```';
+        default:
+            return '```\n' + content + '\n```';
+    }
+}
+
 /**
  * Run Pandoc command safely with execFile
  * @param {string[]} args - Pandoc arguments array
@@ -282,21 +324,60 @@ function createWindow() {
   mainWindow = new BrowserWindow({
     width: 1200,
     height: 800,
+    show: false,
     webPreferences: {
       nodeIntegration: true,
-      contextIsolation: false
+      contextIsolation: false,
+      spellcheck: true
     },
     icon: path.join(__dirname, '../assets/icon.png')
   });
 
   mainWindow.loadFile(path.join(__dirname, 'index.html'));
 
+  // Show window only after content is ready — avoids blank flash
+  mainWindow.once('ready-to-show', () => {
+    mainWindow.show();
+  });
+
   createMenu();
 
   mainWindow.on('closed', () => {
     mainWindow = null;
   });
 
+  // Spell check context menu
+  mainWindow.webContents.on('context-menu', (event, params) => {
+    const { Menu, MenuItem } = require('electron');
+    const menu = new Menu();
+
+    // Add spell check suggestions
+    if (params.misspelledWord) {
+      for (const suggestion of params.dictionarySuggestions) {
+        menu.append(new MenuItem({
+          label: suggestion,
+          click: () => mainWindow.webContents.replaceMisspelling(suggestion)
+        }));
+      }
+      if (params.dictionarySuggestions.length > 0) {
+        menu.append(new MenuItem({ type: 'separator' }));
+      }
+      menu.append(new MenuItem({
+        label: 'Add to Dictionary',
+        click: () => mainWindow.webContents.session.addWordToSpellCheckerDictionary(params.misspelledWord)
+      }));
+      menu.append(new MenuItem({ type: 'separator' }));
+    }
+
+    // Standard context menu items
+    menu.append(new MenuItem({ role: 'cut' }));
+    menu.append(new MenuItem({ role: 'copy' }));
+    menu.append(new MenuItem({ role: 'paste' }));
+    menu.append(new MenuItem({ role: 'selectAll' }));
+
+    menu.popup();
+  });
+
   // Wait for the page to fully load before sending file data
   mainWindow.webContents.on('did-finish-load', () => {
     console.log('Window finished loading');
@@ -321,11 +402,16 @@ function buildRecentFilesMenu() {
     label: filePath.split(/[\\/]/).pop(), // Get filename only
     click: () => {
       if (fs.existsSync(filePath)) {
+        const stats = fs.statSync(filePath);
+        if (stats.size > MAX_FILE_SIZE) {
+            dialog.showErrorBox('File Too Large', `File exceeds the ${MAX_FILE_SIZE_MB}MB size limit.`);
+            return;
+        }
         currentFile = filePath;
         const content = fs.readFileSync(filePath, 'utf-8');
         mainWindow.webContents.send('file-opened', { path: filePath, content });
       } else {
-        dialog.showErrorBox('File Not Found', `The file "${filePath}" could not be found.`);
+        dialog.showErrorBox('File Not Found', sanitizeErrorMessage(`The file "${filePath}" could not be found.`));
       }
     },
     toolTip: filePath // Show full path in tooltip
@@ -403,6 +489,22 @@ function createMenu() {
           submenu: buildRecentFilesMenu()
         },
         { type: 'separator' },
+        {
+          label: 'New from Template',
+          submenu: [
+            { label: 'Blog Post', click: () => mainWindow.webContents.send('load-template-menu', 'blog-post.md') },
+            { label: 'Meeting Notes', click: () => mainWindow.webContents.send('load-template-menu', 'meeting-notes.md') },
+            { label: 'Technical Spec', click: () => mainWindow.webContents.send('load-template-menu', 'technical-spec.md') },
+            { label: 'Changelog', click: () => mainWindow.webContents.send('load-template-menu', 'changelog.md') },
+            { label: 'README', click: () => mainWindow.webContents.send('load-template-menu', 'readme.md') },
+            { label: 'Project Plan', click: () => mainWindow.webContents.send('load-template-menu', 'project-plan.md') },
+            { label: 'API Documentation', click: () => mainWindow.webContents.send('load-template-menu', 'api-docs.md') },
+            { label: 'Tutorial', click: () => mainWindow.webContents.send('load-template-menu', 'tutorial.md') },
+            { label: 'Release Notes', click: () => mainWindow.webContents.send('load-template-menu', 'release-notes.md') },
+            { label: 'Comparison', click: () => mainWindow.webContents.send('load-template-menu', 'comparison.md') }
+          ]
+        },
+        { type: 'separator' },
         {
           label: 'Import Document...',
           accelerator: 'CmdOrCtrl+I',
@@ -425,6 +527,17 @@ function createMenu() {
             { label: 'OpenDocument Presentation (ODP)', click: () => exportFile('odp') },
             { type: 'separator' },
             { label: 'CSV (Tables)', click: () => exportSpreadsheet('csv') },
+            { type: 'separator' },
+            { label: 'JSON (.json)', click: () => exportFile('json') },
+            { label: 'YAML (.yaml)', click: () => exportFile('yaml') },
+            { label: 'XML (.xml)', click: () => exportFile('xml') },
+            { label: 'TOML (.toml)', click: () => exportFile('toml') },
+            { type: 'separator' },
+            { label: 'Reveal.js Slides (.html)', click: () => exportFile('revealjs') },
+            { label: 'Beamer Slides (.pdf)', click: () => exportFile('beamer') },
+            { type: 'separator' },
+            { label: 'Confluence Wiki (.txt)', click: () => exportFile('confluence') },
+            { label: 'MOBI E-book (.mobi)', click: () => exportFile('mobi') },
           ]
         },
         { type: 'separator' },
@@ -483,9 +596,29 @@ function createMenu() {
       submenu: [
         {
           label: 'Toggle Preview',
-          accelerator: 'CmdOrCtrl+Shift+P',
+          accelerator: 'CmdOrCtrl+Shift+V',
           click: () => mainWindow.webContents.send('toggle-preview')
         },
+        {
+          label: 'Command Palette',
+          accelerator: 'CmdOrCtrl+Shift+P',
+          click: () => mainWindow.webContents.send('toggle-command-palette')
+        },
+        { type: 'separator' },
+        {
+          label: 'Sidebar',
+          submenu: [
+            { label: 'File Explorer', click: () => mainWindow.webContents.send('toggle-sidebar-panel', 'explorer') },
+            { label: 'Git', click: () => mainWindow.webContents.send('toggle-sidebar-panel', 'git') },
+            { label: 'Snippets', click: () => mainWindow.webContents.send('toggle-sidebar-panel', 'snippets') },
+            { label: 'Templates', click: () => mainWindow.webContents.send('toggle-sidebar-panel', 'templates') }
+          ]
+        },
+        {
+          label: 'Bottom Panel (REPL)',
+          click: () => mainWindow.webContents.send('toggle-bottom-panel')
+        },
+        { type: 'separator' },
         {
           label: 'Theme',
           submenu: [
@@ -541,6 +674,15 @@ function createMenu() {
           ]
         },
         { type: 'separator' },
+        {
+          label: 'Spell Check',
+          type: 'checkbox',
+          checked: true,
+          click: (menuItem) => {
+            mainWindow.webContents.session.setSpellCheckerEnabled(menuItem.checked);
+          }
+        },
+        { type: 'separator' },
         { label: 'Reload', accelerator: 'CmdOrCtrl+R', role: 'reload' },
         { label: 'Toggle DevTools', accelerator: 'F12', role: 'toggleDevTools' },
         { type: 'separator' },
@@ -783,7 +925,7 @@ function showAboutDialog() {
 <body>
   <img src="${iconBase64}" class="logo" alt="MarkdownConverter">
   <h1>MarkdownConverter</h1>
-  <div class="version">Version 3.0.0</div>
+  <div class="version">Version 4.0.0</div>
 
   <div class="company">
     <span>by</span>
@@ -812,7 +954,7 @@ function showAboutDialog() {
 
   <div class="footer">
     <p>License: MIT</p>
-    <p>© 2024-2025 ConcreteInfo. All rights reserved.</p>
+    <p>© 2024-2026 ConcreteInfo. All rights reserved.</p>
   </div>
 </body>
 </html>`;
@@ -945,6 +1087,11 @@ function openPDFFile() {
   });
 
   if (files && files[0]) {
+    const stats = fs.statSync(files[0]);
+    if (stats.size > MAX_FILE_SIZE) {
+        dialog.showErrorBox('File Too Large', `File exceeds the ${MAX_FILE_SIZE_MB}MB size limit.`);
+        return;
+    }
     mainWindow.webContents.send('open-pdf-viewer', files[0]);
   }
 }
@@ -954,13 +1101,27 @@ function openFile() {
     properties: ['openFile'],
     filters: [
       { name: 'Markdown', extensions: ['md', 'markdown'] },
+      { name: 'Developer Formats', extensions: ['json', 'yaml', 'yml', 'xml', 'toml'] },
       { name: 'All Files', extensions: ['*'] }
     ]
   });
 
   if (files && files[0]) {
+    const stats = fs.statSync(files[0]);
+    if (stats.size > MAX_FILE_SIZE) {
+        dialog.showErrorBox('File Too Large', `File exceeds the ${MAX_FILE_SIZE_MB}MB size limit.`);
+        return;
+    }
     currentFile = files[0];
-    const content = fs.readFileSync(currentFile, 'utf-8');
+    const ext = path.extname(currentFile).toLowerCase().slice(1);
+    let content = fs.readFileSync(currentFile, 'utf-8');
+
+    // Wrap developer format files in code blocks for markdown display
+    const devFormats = ['json', 'yaml', 'yml', 'xml', 'toml'];
+    if (devFormats.includes(ext)) {
+      content = convertDataToMarkdown(content, ext);
+    }
+
     mainWindow.webContents.send('file-opened', { path: currentFile, content });
   }
 }
@@ -975,6 +1136,11 @@ function openPdfFile() {
   });
 
   if (files && files[0]) {
+    const stats = fs.statSync(files[0]);
+    if (stats.size > MAX_FILE_SIZE) {
+        dialog.showErrorBox('File Too Large', `File exceeds the ${MAX_FILE_SIZE_MB}MB size limit.`);
+        return;
+    }
     mainWindow.webContents.send('open-pdf-file', files[0]);
   }
 }
@@ -1158,7 +1324,7 @@ ipcMain.on('browse-header-footer-logo', async (event, position) => {
     }
   } catch (error) {
     console.error('Logo browse error:', error);
-    dialog.showErrorBox('Logo Error', `Failed to select logo: ${error.message}`);
+    dialog.showErrorBox('Logo Error', sanitizeErrorMessage(`Failed to select logo: ${error.message}`));
   }
 });
 
@@ -1180,7 +1346,7 @@ ipcMain.on('save-header-footer-logo', async (event, { position, filePath }) => {
 
     // Verify source file exists
     if (!fs.existsSync(filePath)) {
-      dialog.showErrorBox('Logo Error', `Source file not found: ${filePath}`);
+      dialog.showErrorBox('Logo Error', sanitizeErrorMessage(`Source file not found: ${filePath}`));
       return;
     }
 
@@ -1202,7 +1368,7 @@ ipcMain.on('save-header-footer-logo', async (event, { position, filePath }) => {
     event.reply('header-footer-logo-saved', { position, path: destPath });
   } catch (error) {
     console.error('Logo save error:', error);
-    dialog.showErrorBox('Logo Error', `Failed to save logo: ${error.message}`);
+    dialog.showErrorBox('Logo Error', sanitizeErrorMessage(`Failed to save logo: ${error.message}`));
   }
 });
 
@@ -1457,7 +1623,7 @@ async function exportWordWithTemplate() {
     });
 
   } catch (error) {
-    dialog.showErrorBox('Export Error', `Failed to export document: ${error.message}`);
+    dialog.showErrorBox('Export Error', sanitizeErrorMessage(`Failed to export document: ${error.message}`));
   }
 }
 
@@ -1505,7 +1671,7 @@ async function exportPDFViaWordTemplate() {
 
       if (error) {
         dialog.showErrorBox('PDF Conversion Error',
-          `Failed to convert to PDF. Please ensure LibreOffice is installed.\n\nError: ${error.message}`);
+          sanitizeErrorMessage(`Failed to convert to PDF. Please ensure LibreOffice is installed.\n\nError: ${error.message}`));
         return;
       }
 
@@ -1530,7 +1696,7 @@ async function exportPDFViaWordTemplate() {
     });
 
   } catch (error) {
-    dialog.showErrorBox('Export Error', `Failed to export PDF: ${error.message}`);
+    dialog.showErrorBox('Export Error', sanitizeErrorMessage(`Failed to export PDF: ${error.message}`));
   }
 }
 
@@ -1579,6 +1745,10 @@ function checkConverterAvailable(tool) {
 
 // Handle universal file conversion
 ipcMain.on('universal-convert', async (event, { tool, fromFormat, toFormat, filePath }) => {
+  if (!conversionLimiter()) {
+    mainWindow.webContents.send('conversion-status', 'Please wait before converting again...');
+    return;
+  }
   try {
     mainWindow.webContents.send('conversion-status', 'Checking converter availability...');
 
@@ -1657,6 +1827,91 @@ ipcMain.on('universal-convert', async (event, { tool, fromFormat, toFormat, file
   }
 });
 
+// Handle universal batch file conversion
+ipcMain.on('universal-convert-batch', async (event, { tool, fromFormat, toFormat, inputFolder, outputFolder, includeSubfolders, advancedOptions }) => {
+  if (!conversionLimiter()) {
+    mainWindow.webContents.send('conversion-status', 'Please wait before converting again...');
+    return;
+  }
+  try {
+    const toolAvailable = await checkConverterAvailable(tool);
+    if (!toolAvailable) {
+      throw new Error(`${tool} is not installed or not found in PATH. Please install it first.`);
+    }
+
+    // Collect matching files
+    const files = [];
+    function collectFiles(dir) {
+      const entries = fs.readdirSync(dir, { withFileTypes: true });
+      for (const entry of entries) {
+        const fullPath = path.join(dir, entry.name);
+        if (entry.isDirectory() && includeSubfolders) {
+          collectFiles(fullPath);
+        } else if (entry.isFile() && entry.name.toLowerCase().endsWith(`.${fromFormat}`)) {
+          files.push(fullPath);
+        }
+      }
+    }
+    collectFiles(inputFolder);
+
+    if (files.length === 0) {
+      mainWindow.webContents.send('conversion-complete', { success: false, error: `No .${fromFormat} files found in the selected folder.` });
+      return;
+    }
+
+    let completed = 0;
+    let failed = 0;
+
+    for (const filePath of files) {
+      const relativePath = path.relative(inputFolder, filePath);
+      const outputPath = path.join(outputFolder, relativePath.replace(/\.[^/.]+$/, `.${toFormat}`));
+
+      // Ensure output subdirectory exists
+      fs.mkdirSync(path.dirname(outputPath), { recursive: true });
+
+      mainWindow.webContents.send('conversion-status', `Converting ${completed + 1}/${files.length}: ${path.basename(filePath)}`);
+
+      let conversionInfo;
+      switch (tool) {
+        case 'libreoffice': conversionInfo = convertWithLibreOffice(filePath, toFormat, outputPath); break;
+        case 'imagemagick': conversionInfo = convertWithImageMagick(filePath, outputPath); break;
+        case 'ffmpeg': conversionInfo = convertWithFFmpeg(filePath, outputPath); break;
+        case 'pandoc': conversionInfo = convertWithPandoc(filePath, outputPath); break;
+        default: throw new Error(`Unknown conversion tool: ${tool}`);
+      }
+
+      await new Promise((resolve) => {
+        execFile(conversionInfo.command, conversionInfo.args, (error) => {
+          if (error) { failed++; } else { completed++; }
+          resolve();
+        });
+      });
+    }
+
+    mainWindow.webContents.send('conversion-complete', {
+      success: true,
+      outputPath: outputFolder
+    });
+
+    dialog.showMessageBox(mainWindow, {
+      type: 'info',
+      title: 'Batch Conversion Complete',
+      message: `Batch conversion finished!`,
+      detail: `Converted: ${completed}/${files.length} files${failed > 0 ? ` (${failed} failed)` : ''}\nOutput: ${outputFolder}`,
+      buttons: ['OK']
+    });
+  } catch (error) {
+    mainWindow.webContents.send('conversion-complete', { success: false, error: error.message });
+    dialog.showMessageBox(mainWindow, {
+      type: 'error',
+      title: 'Batch Conversion Failed',
+      message: 'Batch conversion failed',
+      detail: error.message,
+      buttons: ['OK']
+    });
+  }
+});
+
 // LibreOffice conversion - returns {command, args} for execFile (safer than exec)
 function convertWithLibreOffice(inputFile, outputFormat, outputPath) {
   const outputDir = path.dirname(outputPath);
@@ -1717,10 +1972,19 @@ function convertWithPandoc(inputFile, outputPath) {
 }
 
 function performExportWithOptions(format, options) {
+  // Map format names to file extensions
+  const formatExtMap = {
+    revealjs: 'html',
+    beamer: 'pdf',
+    confluence: 'txt',
+    jira: 'txt',
+  };
+  const fileExt = formatExtMap[format] || format;
+
   const outputFile = dialog.showSaveDialogSync(mainWindow, {
-    defaultPath: currentFile.replace(/\.[^/.]+$/, `.${format}`),
+    defaultPath: currentFile.replace(/\.[^/.]+$/, `.${fileExt}`),
     filters: [
-      { name: format.toUpperCase(), extensions: [format] }
+      { name: format.toUpperCase(), extensions: [fileExt] }
     ]
   });
 
@@ -1851,13 +2115,59 @@ function performExportWithOptions(format, options) {
         pandocCmd += ` --variable footer="${footerText}"`;
       }
       exportWithPandoc(pandocCmd, outputFile, format);
+    } else if (format === 'json') {
+      pandocCmd = `${getPandocPath()} "${currentFile}" -t json -o "${outputFile}"`;
+      exportWithPandoc(pandocCmd, outputFile, format);
+    } else if (format === 'yaml' || format === 'xml' || format === 'toml') {
+      // For YAML/XML/TOML, save the raw markdown content with the new extension
+      try {
+        const content = fs.readFileSync(currentFile, 'utf-8');
+        fs.writeFileSync(outputFile, content, 'utf-8');
+        showExportSuccess(outputFile);
+      } catch (err) {
+        dialog.showErrorBox('Export Error', sanitizeErrorMessage(`Failed to export: ${err.message}`));
+      }
+    } else if (format === 'revealjs') {
+      pandocCmd = `${getPandocPath()} "${currentFile}" -t revealjs -s -o "${outputFile}" --slide-level=2`;
+      exportWithPandoc(pandocCmd, outputFile, format);
+    } else if (format === 'beamer') {
+      pandocCmd = `${getPandocPath()} "${currentFile}" -t beamer -o "${outputFile}"`;
+      exportWithPandoc(pandocCmd, outputFile, format);
+    } else if (format === 'confluence' || format === 'jira') {
+      pandocCmd = `${getPandocPath()} "${currentFile}" -t jira -o "${outputFile}"`;
+      exportWithPandoc(pandocCmd, outputFile, format);
+    } else if (format === 'mobi') {
+      // First export to EPUB, then try ebook-convert if available
+      const epubFile = outputFile.replace(/\.mobi$/i, '.epub');
+      pandocCmd = `${getPandocPath()} "${currentFile}" -o "${epubFile}"`;
+      runPandocCmd(pandocCmd, (error) => {
+        if (error) {
+          dialog.showErrorBox('Export Error', sanitizeErrorMessage(`Failed to export EPUB intermediate: ${error.message}`));
+          return;
+        }
+        // Try ebook-convert (Calibre) for MOBI
+        execFile('ebook-convert', [epubFile, outputFile], (ebookError) => {
+          if (ebookError) {
+            dialog.showMessageBox(mainWindow, {
+              type: 'warning',
+              title: 'MOBI Export - Partial',
+              message: `Calibre's ebook-convert was not found. The file has been exported as EPUB instead.\n\nEPUB saved to: ${epubFile}\n\nTo get MOBI output, install Calibre from: https://calibre-ebook.com/`,
+              buttons: ['OK']
+            });
+          } else {
+            // Clean up intermediate EPUB
+            try { fs.unlinkSync(epubFile); } catch (e) { /* ignore */ }
+            showExportSuccess(outputFile);
+          }
+        });
+      });
     } else {
       // Generic export for other formats
       exportWithPandoc(pandocCmd, outputFile, format);
     }
   }).catch((error) => {
     console.error('Error checking pandoc availability:', error);
-    dialog.showErrorBox('Export Error', `Error checking system requirements: ${error.message}`);
+    dialog.showErrorBox('Export Error', sanitizeErrorMessage(`Error checking system requirements: ${error.message}`));
   });
 }
 
@@ -1967,7 +2277,7 @@ function exportWithPandoc(pandocCmd, outputFile, format) {
 
       errorMessage += `\n\nCommand used: ${pandocCmd}`;
 
-      dialog.showErrorBox('Export Error', errorMessage);
+      dialog.showErrorBox('Export Error', sanitizeErrorMessage(errorMessage));
     } else {
       console.log(`Successfully exported to ${format}:`, outputFile);
       console.log(`Pandoc stdout:`, stdout);
@@ -2159,7 +2469,7 @@ function exportToHTML(outputFile) {
     showExportSuccess(outputFile);
   } catch (error) {
     console.error('HTML export error:', error);
-    dialog.showErrorBox('HTML Export Error', `Failed to export HTML: ${error.message}`);
+    dialog.showErrorBox('HTML Export Error', sanitizeErrorMessage(`Failed to export HTML: ${error.message}`));
   }
 }
 
@@ -2291,13 +2601,13 @@ function exportToPDFElectron(outputFile) {
       pdfWindow.close();
       console.error('Electron PDF export error:', error);
       dialog.showErrorBox('PDF Export Error',
-        `Failed to export PDF using built-in engine: ${error.message}\n\n` +
-        `For better PDF export, please install Pandoc with LaTeX support.`
+        sanitizeErrorMessage(`Failed to export PDF using built-in engine: ${error.message}\n\n` +
+        `For better PDF export, please install Pandoc with LaTeX support.`)
       );
     });
   } catch (error) {
     console.error('PDF export setup error:', error);
-    dialog.showErrorBox('PDF Export Error', `Failed to setup PDF export: ${error.message}`);
+    dialog.showErrorBox('PDF Export Error', sanitizeErrorMessage(`Failed to setup PDF export: ${error.message}`));
   }
 }
 
@@ -2323,13 +2633,18 @@ function importDocument() {
       { name: 'Web Formats', extensions: ['html', 'htm', 'xhtml'] },
       { name: 'Wiki Formats', extensions: ['mediawiki', 'dokuwiki', 'tikiwiki', 'twiki'] },
       { name: 'CSV/TSV', extensions: ['csv', 'tsv'] },
-      { name: 'JSON', extensions: ['json'] },
+      { name: 'Developer Formats', extensions: ['json', 'yaml', 'yml', 'xml', 'toml'] },
       { name: 'All Files', extensions: ['*'] }
     ]
   });
 
   if (files && files[0]) {
     const inputFile = files[0];
+    const stats = fs.statSync(inputFile);
+    if (stats.size > MAX_FILE_SIZE) {
+        dialog.showErrorBox('File Too Large', `File exceeds the ${MAX_FILE_SIZE_MB}MB size limit.`);
+        return;
+    }
     const ext = path.extname(inputFile).toLowerCase().slice(1);
     const outputFile = inputFile.replace(/\.[^/.]+$/, '.md');
 
@@ -2351,12 +2666,29 @@ function importDocument() {
       additionalOptions = '--from=json -t markdown';
     }
 
+    // For YAML, XML, TOML - wrap content in code blocks directly
+    if (['yaml', 'yml', 'xml', 'toml'].includes(ext)) {
+      const rawContent = fs.readFileSync(inputFile, 'utf-8');
+      const mdContent = convertDataToMarkdown(rawContent, ext);
+      const mdOutputFile = inputFile.replace(/\.[^/.]+$/, '.md');
+      fs.writeFileSync(mdOutputFile, mdContent, 'utf-8');
+      currentFile = mdOutputFile;
+      mainWindow.webContents.send('file-opened', { path: mdOutputFile, content: mdContent });
+      dialog.showMessageBox(mainWindow, {
+        type: 'info',
+        title: 'Import Complete',
+        message: `Document imported successfully as ${path.basename(mdOutputFile)}\n\nOriginal format: ${ext.toUpperCase()}\nConverted to: Markdown`,
+        buttons: ['OK']
+      });
+      return;
+    }
+
     // Convert to markdown using pandoc (using runPandocCmd for safety)
     const pandocCmd = `${getPandocPath()} "${inputFile}" -t markdown ${additionalOptions} -o "${outputFile}"`;
 
     runPandocCmd(pandocCmd, (error, stdout, stderr) => {
       if (error) {
-        dialog.showErrorBox('Import Error', `Failed to import: ${error.message}\n\nMake sure Pandoc is installed.\n\nSupported formats: DOCX, ODT, RTF, HTML, LaTeX, EPUB, PDF, PPTX, ODP, RST, Textile, MediaWiki, Org-mode, AsciiDoc, CSV, and more.`);
+        dialog.showErrorBox('Import Error', sanitizeErrorMessage(`Failed to import: ${error.message}\n\nMake sure Pandoc is installed.\n\nSupported formats: DOCX, ODT, RTF, HTML, LaTeX, EPUB, PDF, PPTX, ODP, RST, Textile, MediaWiki, Org-mode, AsciiDoc, CSV, and more.`));
       } else {
         // Open the converted markdown file
         currentFile = outputFile;
@@ -2418,6 +2750,32 @@ ipcMain.on('do-print', (event, { withStyles }) => {
   }
 });
 
+// Handle printing with custom options from print preview dialog
+ipcMain.on('do-print-with-options', (event, options) => {
+  if (!mainWindow) return;
+
+  const marginsMap = {
+    'default': { marginType: 'default' },
+    'narrow': { top: 0.4, bottom: 0.4, left: 0.4, right: 0.4 },
+    'wide': { top: 1.0, bottom: 1.0, left: 1.0, right: 1.0 },
+    'none': { top: 0, bottom: 0, left: 0, right: 0 },
+  };
+
+  const printOptions = {
+    silent: false,
+    printBackground: options.background,
+    landscape: options.orientation === 'landscape',
+    scaleFactor: options.scale / 100,
+    pageSize: options.paperSize,
+  };
+
+  if (options.margins && options.margins !== 'default') {
+    printOptions.margins = marginsMap[options.margins];
+  }
+
+  mainWindow.webContents.print(printOptions);
+});
+
 // Handle renderer ready for file association
 ipcMain.on('renderer-ready', (event) => {
   console.log('[MAIN] renderer-ready received, rendererReady was:', rendererReady);
@@ -2441,11 +2799,19 @@ ipcMain.on('renderer-ready', (event) => {
 
 // Handle export with options
 ipcMain.on('export-with-options', (event, { format, options }) => {
+  if (!conversionLimiter()) {
+    mainWindow.webContents.send('conversion-status', 'Please wait before converting again...');
+    return;
+  }
   performExportWithOptions(format, options);
 });
 
 // Handle batch conversion
 ipcMain.on('batch-convert', (event, { inputFolder, outputFolder, format, options }) => {
+  if (!conversionLimiter()) {
+    mainWindow.webContents.send('conversion-status', 'Please wait before converting again...');
+    return;
+  }
   performBatchConversion(inputFolder, outputFolder, format, options);
 });
 
@@ -2506,7 +2872,7 @@ ipcMain.on('export-spreadsheet', (event, { content, format }) => {
         buttons: ['OK']
       });
     } catch (error) {
-      dialog.showErrorBox('Export Error', `Failed to export: ${error.message}`);
+      dialog.showErrorBox('Export Error', sanitizeErrorMessage(`Failed to export: ${error.message}`));
     }
   }
 });
@@ -2564,7 +2930,7 @@ function performBatchConversion(inputFolder, outputFolder, format, options) {
     try {
       fs.mkdirSync(outputFolder, { recursive: true });
     } catch (error) {
-      dialog.showErrorBox('Error', `Failed to create output folder: ${error.message}`);
+      dialog.showErrorBox('Error', sanitizeErrorMessage(`Failed to create output folder: ${error.message}`));
       return;
     }
   }
@@ -3077,6 +3443,36 @@ function buildPandocCommand(content, format, outputPath) {
         command += ` --variable footer="${footerText}"`;
       }
       break;
+
+    case 'json':
+      command = `pandoc "${inputFile}" -t json -o "${outputPath}"`;
+      break;
+
+    case 'yaml':
+      command = `pandoc "${inputFile}" -t markdown -o "${outputPath}"`;
+      break;
+
+    case 'xml':
+      command = `pandoc "${inputFile}" -t jats -o "${outputPath}"`;
+      break;
+
+    case 'toml':
+      // TOML: save raw markdown content with .toml extension
+      command = `pandoc "${inputFile}" -t markdown -o "${outputPath}"`;
+      break;
+
+    case 'revealjs':
+      command = `pandoc "${inputFile}" -t revealjs -s -o "${outputPath}" --slide-level=2`;
+      break;
+
+    case 'beamer':
+      command = `pandoc "${inputFile}" -t beamer -o "${outputPath}"`;
+      break;
+
+    case 'confluence':
+    case 'jira':
+      command = `pandoc "${inputFile}" -t jira -o "${outputPath}"`;
+      break;
   }
 
   return command;
@@ -3192,6 +3588,11 @@ function openFileFromPath(filePath) {
   console.log('[MAIN] openFileFromPath called with:', filePath);
   console.log('[MAIN] rendererReady:', rendererReady, 'mainWindow exists:', !!mainWindow);
   if (fs.existsSync(filePath)) {
+    const stats = fs.statSync(filePath);
+    if (stats.size > MAX_FILE_SIZE) {
+        dialog.showErrorBox('File Too Large', `File exceeds the ${MAX_FILE_SIZE_MB}MB size limit.`);
+        return;
+    }
     currentFile = filePath;
     const content = fs.readFileSync(filePath, 'utf-8');
     console.log('[MAIN] File read successfully, content length:', content.length);
@@ -3787,9 +4188,209 @@ ipcMain.on('open-table-generator', () => {
   openTableGenerator();
 });
 
+// IPC Handler for loading document templates
+ipcMain.handle('load-template', async (event, filename) => {
+  try {
+    const templatePath = path.join(__dirname, 'templates', filename);
+    return fs.readFileSync(templatePath, 'utf-8');
+  } catch (err) {
+    console.error('Failed to load template:', err);
+    return null;
+  }
+});
+
+// IPC Handler for saving pasted/dropped images
+ipcMain.handle('save-pasted-image', async (event, { base64, ext }) => {
+  try {
+    let saveDir;
+
+    if (currentFile) {
+      // Save relative to current file
+      saveDir = path.join(path.dirname(currentFile), 'assets');
+    } else {
+      // Use temp directory
+      saveDir = path.join(app.getPath('temp'), 'markdown-converter-images');
+    }
+
+    if (!fs.existsSync(saveDir)) {
+      fs.mkdirSync(saveDir, { recursive: true });
+    }
+
+    const filename = `image-${Date.now()}.${ext}`;
+    const filePath = path.join(saveDir, filename);
+    const buffer = Buffer.from(base64, 'base64');
+    fs.writeFileSync(filePath, buffer);
+
+    return { relativePath: `assets/${filename}`, absolutePath: filePath };
+  } catch (error) {
+    console.error('Failed to save pasted image:', error);
+    return null;
+  }
+});
+
 // IPC Handler to receive generated content from generator windows
 ipcMain.on('insert-generated-content', (event, content) => {
   if (mainWindow && !mainWindow.isDestroyed()) {
     mainWindow.webContents.send('insert-content', content);
   }
 });
+
+// ============================================
+// File Explorer IPC Handlers
+// ============================================
+ipcMain.handle('list-directory', async (event, dirPath) => {
+  try {
+    if (!dirPath) {
+      const result = await dialog.showOpenDialog(mainWindow, {
+        properties: ['openDirectory']
+      });
+      if (result.canceled || !result.filePaths[0]) return null;
+      dirPath = result.filePaths[0];
+    }
+    const entries = fs.readdirSync(dirPath, { withFileTypes: true })
+      .filter(e => !e.name.startsWith('.'))
+      .sort((a, b) => {
+        if (a.isDirectory() && !b.isDirectory()) return -1;
+        if (!a.isDirectory() && b.isDirectory()) return 1;
+        return a.name.localeCompare(b.name);
+      })
+      .map(e => ({
+        name: e.name,
+        isDirectory: e.isDirectory(),
+        path: path.join(dirPath, e.name)
+      }));
+    return { path: dirPath, entries };
+  } catch (err) {
+    console.error('list-directory error:', err);
+    return null;
+  }
+});
+
+// Open a file by path (from explorer panel)
+ipcMain.on('open-file-path', (event, filePath) => {
+  try {
+    if (!fs.existsSync(filePath)) return;
+    const stat = fs.statSync(filePath);
+    if (stat.size > MAX_FILE_SIZE) return;
+    currentFile = filePath;
+    const content = fs.readFileSync(filePath, 'utf-8');
+    mainWindow.webContents.send('file-opened', { path: filePath, content });
+  } catch (err) {
+    console.error('open-file-path error:', err);
+  }
+});
+
+// ============================================
+// Git IPC Handlers
+// ============================================
+const simpleGit = require('simple-git');
+
+function getGitRepo() {
+  // Use the directory of the current file, or the app's working directory
+  const dir = currentFile ? path.dirname(currentFile) : process.cwd();
+  return simpleGit(dir);
+}
+
+ipcMain.handle('git-status', async () => {
+  try {
+    const git = getGitRepo();
+    return await git.status();
+  } catch (err) {
+    return { error: 'Not a git repository' };
+  }
+});
+
+ipcMain.handle('git-stage', async (event, { files }) => {
+  try {
+    const git = getGitRepo();
+    await git.add(files);
+    return await git.status();
+  } catch (err) {
+    return { error: err.message };
+  }
+});
+
+ipcMain.handle('git-commit', async (event, { message }) => {
+  try {
+    const git = getGitRepo();
+    return await git.commit(message);
+  } catch (err) {
+    return { error: err.message };
+  }
+});
+
+ipcMain.handle('git-log', async () => {
+  try {
+    const git = getGitRepo();
+    return await git.log({ maxCount: 20 });
+  } catch (err) {
+    return { error: err.message };
+  }
+});
+
+// ============================================
+// Snippets IPC Handlers
+// ============================================
+const snippetsPath = path.join(app.getPath('userData'), 'snippets.json');
+
+function loadSnippets() {
+  try {
+    if (fs.existsSync(snippetsPath)) {
+      return JSON.parse(fs.readFileSync(snippetsPath, 'utf-8'));
+    }
+  } catch (err) { console.error('Failed to load snippets:', err); }
+  return [];
+}
+
+function saveSnippetsFile(snippets) {
+  fs.writeFileSync(snippetsPath, JSON.stringify(snippets, null, 2));
+}
+
+ipcMain.handle('get-snippets', async () => loadSnippets());
+
+ipcMain.handle('save-snippet', async (event, snippet) => {
+  const snippets = loadSnippets();
+  const existing = snippets.findIndex(s => s.id === snippet.id);
+  if (existing >= 0) snippets[existing] = snippet;
+  else snippets.push(snippet);
+  saveSnippetsFile(snippets);
+  return snippets;
+});
+
+ipcMain.handle('delete-snippet', async (event, id) => {
+  const snippets = loadSnippets().filter(s => s.id !== id);
+  saveSnippetsFile(snippets);
+  return snippets;
+});
+
+// ============================================
+// Code Execution (REPL) IPC Handler
+// ============================================
+ipcMain.handle('execute-code', async (event, { code, language }) => {
+  const timeout = 10000;
+
+  return new Promise((resolve) => {
+    let cmd, args;
+    if (language === 'javascript' || language === 'js') {
+      cmd = 'node';
+      args = ['-e', code];
+    } else if (language === 'python' || language === 'py') {
+      cmd = process.platform === 'win32' ? 'python' : 'python3';
+      args = ['-c', code];
+    } else if (language === 'bash' || language === 'sh') {
+      cmd = process.platform === 'win32' ? 'cmd' : 'bash';
+      args = process.platform === 'win32' ? ['/c', code] : ['-c', code];
+    } else {
+      resolve({ error: `Unsupported language: ${language}` });
+      return;
+    }
+
+    execFile(cmd, args, { timeout, maxBuffer: 1024 * 1024 }, (err, stdout, stderr) => {
+      resolve({
+        stdout: stdout || '',
+        stderr: stderr || '',
+        error: err?.killed ? 'Execution timed out (10s limit)' : (err?.message || null)
+      });
+    });
+  });
+});

src/preload.js

@@ -9,7 +9,7 @@
  * - All IPC channels are explicitly whitelisted
  * - Prevents XSS from escalating to full system access
  *
- * @version 2.2.0
+ * @version 4.0.0
  */
 
 const { contextBridge, ipcRenderer } = require('electron');
@@ -29,6 +29,7 @@ const ALLOWED_SEND_CHANNELS = [
 
   // Print
   'do-print',
+  'do-print-with-options',
 
   // Export
   'export-with-options',
@@ -90,7 +91,43 @@ const ALLOWED_SEND_CHANNELS = [
   'open-table-generator',
 
   // Insert generated content
-  'insert-generated-content'
+  'insert-generated-content',
+
+  // Image paste/drop
+  'save-pasted-image',
+
+  // Templates
+  'load-template',
+
+  // File Explorer
+  'list-directory',
+
+  // Git
+  'git-status',
+  'git-stage',
+  'git-commit',
+  'git-log',
+
+  // Snippets
+  'get-snippets',
+  'save-snippet',
+  'delete-snippet',
+
+  // Code execution (REPL)
+  'execute-code',
+
+  // File open by path
+  'open-file-path',
+
+  // PDF editor from toolbar
+  'show-pdf-editor-from-toolbar',
+
+  // Menu triggers
+  'menu-open',
+  'export',
+
+  // Git diff
+  'git-diff'
 ];
 
 const ALLOWED_RECEIVE_CHANNELS = [
@@ -176,7 +213,16 @@ const ALLOWED_RECEIVE_CHANNELS = [
   'pdf-operation-progress',
 
   // Insert content from generator windows
-  'insert-content'
+  'insert-content',
+
+  // Batch converter
+  'show-batch-converter',
+
+  // v4 menu-triggered events
+  'load-template-menu',
+  'toggle-command-palette',
+  'toggle-sidebar-panel',
+  'toggle-bottom-panel'
 ];
 
 /**

src/print-preview.js

@@ -0,0 +1,139 @@
+class PrintPreview {
+    constructor() {
+        this.overlay = document.getElementById('print-preview-overlay');
+        this._lastContent = '';
+        this.setupEventListeners();
+    }
+
+    open(htmlContent) {
+        this._lastContent = htmlContent;
+        this.overlay.classList.remove('hidden');
+        this.updatePreview(htmlContent);
+        this.updateScaleLabel();
+    }
+
+    close() {
+        this.overlay.classList.add('hidden');
+    }
+
+    setupEventListeners() {
+        document.getElementById('print-preview-close')?.addEventListener('click', () => this.close());
+        document.getElementById('print-cancel')?.addEventListener('click', () => this.close());
+        document.getElementById('print-execute')?.addEventListener('click', () => this.executePrint());
+
+        // Update preview on option changes
+        ['print-paper-size', 'print-orientation', 'print-margins'].forEach(id => {
+            document.getElementById(id)?.addEventListener('change', () => this.refreshPreview());
+        });
+
+        // Scale slider
+        const scaleSlider = document.getElementById('print-scale');
+        scaleSlider?.addEventListener('input', () => this.updateScaleLabel());
+
+        // Page range toggle
+        document.getElementById('print-pages')?.addEventListener('change', (e) => {
+            const rangeInput = document.getElementById('print-page-range');
+            if (rangeInput) {
+                rangeInput.classList.toggle('hidden', e.target.value !== 'custom');
+            }
+        });
+
+        // Close on overlay click
+        this.overlay?.addEventListener('click', (e) => {
+            if (e.target === this.overlay) this.close();
+        });
+
+        // Close on Escape
+        document.addEventListener('keydown', (e) => {
+            if (e.key === 'Escape' && !this.overlay.classList.contains('hidden')) {
+                this.close();
+            }
+        });
+    }
+
+    updateScaleLabel() {
+        const scale = document.getElementById('print-scale')?.value || 100;
+        const label = document.getElementById('print-scale-value');
+        if (label) label.textContent = `${scale}%`;
+    }
+
+    updatePreview(htmlContent) {
+        const frame = document.getElementById('print-preview-frame');
+        if (!frame) return;
+
+        this._lastContent = htmlContent;
+
+        const orientation = document.getElementById('print-orientation')?.value || 'portrait';
+        const paperSize = document.getElementById('print-paper-size')?.value || 'A4';
+
+        // Get dimensions for paper size
+        const sizes = {
+            'A3': { width: '297mm', height: '420mm' },
+            'A4': { width: '210mm', height: '297mm' },
+            'A5': { width: '148mm', height: '210mm' },
+            'Letter': { width: '8.5in', height: '11in' },
+            'Legal': { width: '8.5in', height: '14in' },
+            'Tabloid': { width: '11in', height: '17in' },
+        };
+
+        const size = sizes[paperSize] || sizes['A4'];
+        const width = orientation === 'landscape' ? size.height : size.width;
+        const height = orientation === 'landscape' ? size.width : size.height;
+
+        const previewHtml = `
+            <!DOCTYPE html>
+            <html>
+            <head>
+                <style>
+                    body {
+                        margin: 20px;
+                        font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
+                        font-size: 14px;
+                        line-height: 1.6;
+                    }
+                    @page { size: ${width} ${height}; }
+                    pre { background: #f5f5f5; padding: 12px; border-radius: 6px; overflow-x: auto; }
+                    code { background: #f0f0f0; padding: 2px 6px; border-radius: 3px; font-size: 13px; }
+                    pre code { background: none; padding: 0; }
+                    table { border-collapse: collapse; width: 100%; }
+                    th, td { border: 1px solid #ddd; padding: 8px; }
+                    blockquote { border-left: 4px solid #ddd; margin-left: 0; padding-left: 16px; color: #666; }
+                    img { max-width: 100%; }
+                    h1, h2, h3 { margin-top: 1.5em; }
+                </style>
+            </head>
+            <body>${htmlContent || ''}</body>
+            </html>
+        `;
+
+        frame.srcdoc = previewHtml;
+    }
+
+    refreshPreview() {
+        if (this._lastContent) {
+            this.updatePreview(this._lastContent);
+        }
+    }
+
+    getOptions() {
+        return {
+            paperSize: document.getElementById('print-paper-size')?.value || 'A4',
+            orientation: document.getElementById('print-orientation')?.value || 'portrait',
+            margins: document.getElementById('print-margins')?.value || 'default',
+            scale: parseInt(document.getElementById('print-scale')?.value || '100'),
+            headers: document.getElementById('print-headers')?.checked ?? true,
+            background: document.getElementById('print-background')?.checked ?? true,
+            pages: document.getElementById('print-pages')?.value || 'all',
+            pageRange: document.getElementById('print-page-range')?.value || '',
+        };
+    }
+
+    executePrint() {
+        const options = this.getOptions();
+        const { ipcRenderer } = require('electron');
+        ipcRenderer.send('do-print-with-options', options);
+        this.close();
+    }
+}
+
+module.exports = { PrintPreview };

src/repl/repl-panel.js

@@ -0,0 +1,49 @@
+class ReplPanel {
+    constructor() {
+        this.panel = document.getElementById('bottom-panel');
+        this.output = document.getElementById('repl-output');
+        this.setupEventListeners();
+    }
+
+    setupEventListeners() {
+        document.getElementById('bottom-panel-toggle')?.addEventListener('click', () => this.toggle());
+        document.getElementById('repl-clear')?.addEventListener('click', () => this.clear());
+    }
+
+    toggle() {
+        this.panel.classList.toggle('collapsed');
+        const btn = document.getElementById('bottom-panel-toggle');
+        if (btn) btn.textContent = this.panel.classList.contains('collapsed') ? '\u25BC' : '\u25B2';
+    }
+
+    show() {
+        this.panel.classList.remove('collapsed');
+        const btn = document.getElementById('bottom-panel-toggle');
+        if (btn) btn.textContent = '\u25B2';
+    }
+
+    clear() {
+        if (this.output) this.output.innerHTML = '';
+    }
+
+    appendOutput(command, result) {
+        const entry = document.createElement('div');
+        entry.className = 'repl-entry';
+        entry.innerHTML = `
+            <div class="repl-command">\u25B6 ${command}</div>
+            ${result.stdout ? `<div class="repl-stdout">${this.escapeHtml(result.stdout)}</div>` : ''}
+            ${result.stderr ? `<div class="repl-stderr">${this.escapeHtml(result.stderr)}</div>` : ''}
+            ${result.error ? `<div class="repl-error">Error: ${this.escapeHtml(result.error)}</div>` : ''}
+        `;
+        this.output?.appendChild(entry);
+        this.output?.scrollTo(0, this.output.scrollHeight);
+    }
+
+    escapeHtml(text) {
+        const div = document.createElement('div');
+        div.textContent = text;
+        return div.innerHTML;
+    }
+}
+
+module.exports = { ReplPanel };

src/sidebar/explorer-panel.js

@@ -0,0 +1,70 @@
+const path = require('path');
+
+function renderExplorerPanel(container, { listDirectory, onFileOpen, currentDir }) {
+    container.innerHTML = `
+        <div class="explorer-panel">
+            <div class="explorer-toolbar">
+                <input type="text" class="explorer-path" id="explorer-path" value="${currentDir || ''}" placeholder="Open a folder..." readonly>
+                <button class="explorer-browse-btn" id="explorer-browse" title="Browse folder">&#x1F4C2;</button>
+            </div>
+            <div class="explorer-tree" id="explorer-tree"></div>
+        </div>
+    `;
+
+    document.getElementById('explorer-browse')?.addEventListener('click', async () => {
+        const dir = await listDirectory(null); // null means open folder dialog
+        if (dir) {
+            document.getElementById('explorer-path').value = dir.path;
+            renderTree(document.getElementById('explorer-tree'), dir.entries, listDirectory, onFileOpen, dir.path);
+        }
+    });
+
+    if (currentDir) {
+        listDirectory(currentDir).then(dir => {
+            if (dir) renderTree(document.getElementById('explorer-tree'), dir.entries, listDirectory, onFileOpen, currentDir);
+        });
+    }
+}
+
+function renderTree(container, entries, listDirectory, onFileOpen, basePath) {
+    container.innerHTML = entries.map(entry => {
+        if (entry.isDirectory) {
+            return `<div class="tree-item tree-folder collapsed" data-path="${entry.path}">
+                <span class="tree-icon">&#x25B6;</span>
+                <span class="tree-name">${entry.name}</span>
+                <div class="tree-children"></div>
+            </div>`;
+        }
+        return `<div class="tree-item tree-file" data-path="${entry.path}">
+            <span class="tree-icon">${getFileIcon(entry.name)}</span>
+            <span class="tree-name">${entry.name}</span>
+        </div>`;
+    }).join('');
+
+    container.querySelectorAll('.tree-folder').forEach(el => {
+        el.querySelector('.tree-name').addEventListener('click', async () => {
+            const isCollapsed = el.classList.contains('collapsed');
+            if (isCollapsed) {
+                const dir = await listDirectory(el.dataset.path);
+                if (dir) {
+                    const childContainer = el.querySelector('.tree-children');
+                    renderTree(childContainer, dir.entries, listDirectory, onFileOpen, el.dataset.path);
+                }
+            }
+            el.classList.toggle('collapsed');
+            el.querySelector('.tree-icon').textContent = el.classList.contains('collapsed') ? '\u25B6' : '\u25BC';
+        });
+    });
+
+    container.querySelectorAll('.tree-file').forEach(el => {
+        el.addEventListener('click', () => onFileOpen(el.dataset.path));
+    });
+}
+
+function getFileIcon(filename) {
+    const ext = filename.split('.').pop().toLowerCase();
+    const icons = { md: '\u{1F4DD}', js: '\u{1F4DC}', json: '{}', html: '\u{1F310}', css: '\u{1F3A8}', py: '\u{1F40D}', pdf: '\u{1F4D5}', txt: '\u{1F4C4}' };
+    return icons[ext] || '\u{1F4C4}';
+}
+
+module.exports = { renderExplorerPanel };

src/sidebar/git-panel.js

@@ -0,0 +1,84 @@
+function renderGitPanel(container, { gitStatus, gitDiff, gitStage, gitCommit, gitLog }) {
+    container.innerHTML = `
+        <div class="git-panel">
+            <div class="git-section">
+                <h4 class="git-section-title">Changes</h4>
+                <div class="git-changes" id="git-changes">
+                    <p class="git-loading">Loading...</p>
+                </div>
+            </div>
+            <div class="git-section">
+                <h4 class="git-section-title">Commit</h4>
+                <textarea class="git-commit-input" id="git-commit-msg" placeholder="Commit message..." rows="3"></textarea>
+                <button class="git-commit-btn" id="git-commit-btn">Commit</button>
+            </div>
+            <div class="git-section">
+                <h4 class="git-section-title">Recent Commits</h4>
+                <div class="git-log" id="git-log"></div>
+            </div>
+        </div>
+    `;
+
+    loadGitStatus();
+
+    async function loadGitStatus() {
+        const status = await gitStatus();
+        const changesEl = document.getElementById('git-changes');
+        if (!status || !changesEl) return;
+
+        if (status.error) {
+            changesEl.innerHTML = `<p class="git-info">${status.error}</p>`;
+            return;
+        }
+
+        const files = [
+            ...status.modified.map(f => ({ file: f, status: 'M', color: '#f59e0b' })),
+            ...status.not_added.map(f => ({ file: f, status: '?', color: '#6b7280' })),
+            ...status.created.map(f => ({ file: f, status: 'A', color: '#10b981' })),
+            ...status.deleted.map(f => ({ file: f, status: 'D', color: '#ef4444' })),
+            ...status.staged.map(f => ({ file: f, status: 'S', color: '#3b82f6' })),
+        ];
+
+        if (files.length === 0) {
+            changesEl.innerHTML = '<p class="git-info">No changes</p>';
+        } else {
+            changesEl.innerHTML = files.map(f => `
+                <div class="git-file" data-file="${f.file}">
+                    <span class="git-file-status" style="color:${f.color}">${f.status}</span>
+                    <span class="git-file-name">${f.file}</span>
+                    <button class="git-stage-btn" data-file="${f.file}" title="Stage file">+</button>
+                </div>
+            `).join('');
+
+            changesEl.querySelectorAll('.git-stage-btn').forEach(btn => {
+                btn.addEventListener('click', async (e) => {
+                    e.stopPropagation();
+                    await gitStage([btn.dataset.file]);
+                    loadGitStatus();
+                });
+            });
+        }
+
+        // Load log
+        const log = await gitLog();
+        const logEl = document.getElementById('git-log');
+        if (log && logEl) {
+            logEl.innerHTML = (log.all || []).slice(0, 10).map(entry => `
+                <div class="git-log-entry">
+                    <div class="git-log-msg">${entry.message}</div>
+                    <div class="git-log-meta">${entry.date?.substring(0, 10) || ''} &middot; ${entry.author_name || ''}</div>
+                </div>
+            `).join('') || '<p class="git-info">No commits</p>';
+        }
+    }
+
+    document.getElementById('git-commit-btn')?.addEventListener('click', async () => {
+        const msg = document.getElementById('git-commit-msg')?.value?.trim();
+        if (!msg) return;
+        await gitCommit(msg);
+        document.getElementById('git-commit-msg').value = '';
+        loadGitStatus();
+    });
+}
+
+module.exports = { renderGitPanel };

src/sidebar/sidebar-manager.js

@@ -0,0 +1,50 @@
+class SidebarManager {
+    constructor() {
+        this.sidebar = document.getElementById('sidebar');
+        this.panelContent = document.getElementById('sidebar-panel-content');
+        this.panelTitle = document.querySelector('.sidebar-panel-title');
+        this.activePanel = null;
+        this.panels = new Map();
+        this.setupEventListeners();
+    }
+
+    setupEventListeners() {
+        document.querySelectorAll('.sidebar-icon').forEach(btn => {
+            btn.addEventListener('click', () => this.togglePanel(btn.dataset.panel));
+        });
+        document.querySelector('.sidebar-panel-close')?.addEventListener('click', () => this.collapse());
+    }
+
+    registerPanel(name, { title, render }) {
+        this.panels.set(name, { title, render });
+    }
+
+    togglePanel(name) {
+        if (this.activePanel === name) {
+            this.collapse();
+        } else {
+            this.expand(name);
+        }
+    }
+
+    expand(name) {
+        const panel = this.panels.get(name);
+        if (!panel) return;
+        this.sidebar.classList.remove('collapsed');
+        this.panelTitle.textContent = panel.title;
+        this.panelContent.innerHTML = '';
+        panel.render(this.panelContent);
+        this.activePanel = name;
+        document.querySelectorAll('.sidebar-icon').forEach(btn => {
+            btn.classList.toggle('active', btn.dataset.panel === name);
+        });
+    }
+
+    collapse() {
+        this.sidebar.classList.add('collapsed');
+        this.activePanel = null;
+        document.querySelectorAll('.sidebar-icon').forEach(btn => btn.classList.remove('active'));
+    }
+}
+
+module.exports = { SidebarManager };

src/sidebar/snippets-panel.js

@@ -0,0 +1,71 @@
+function renderSnippetsPanel(container, { getSnippets, saveSnippet, deleteSnippet, onInsert }) {
+    container.innerHTML = `
+        <div class="snippets-panel">
+            <div class="snippets-toolbar">
+                <input type="text" class="snippets-search" id="snippets-search" placeholder="Search snippets...">
+                <button class="snippets-add-btn" id="snippets-add" title="Add snippet">+</button>
+            </div>
+            <div class="snippets-list" id="snippets-list"></div>
+        </div>
+    `;
+
+    let snippets = [];
+
+    async function loadSnippets() {
+        snippets = await getSnippets() || [];
+        renderList(document.getElementById('snippets-search')?.value || '');
+    }
+
+    function renderList(query) {
+        const list = document.getElementById('snippets-list');
+        if (!list) return;
+
+        const filtered = query
+            ? snippets.filter(s => s.name.toLowerCase().includes(query.toLowerCase()) || (s.language || '').toLowerCase().includes(query.toLowerCase()))
+            : snippets;
+
+        list.innerHTML = filtered.length ? filtered.map(s => `
+            <div class="snippet-item" data-id="${s.id}">
+                <div class="snippet-header">
+                    <span class="snippet-name">${s.name}</span>
+                    <span class="snippet-lang">${s.language || 'text'}</span>
+                </div>
+                <pre class="snippet-preview"><code>${(s.code || '').substring(0, 100)}${(s.code || '').length > 100 ? '...' : ''}</code></pre>
+                <div class="snippet-actions">
+                    <button class="snippet-insert" data-id="${s.id}" title="Insert">Insert</button>
+                    <button class="snippet-delete" data-id="${s.id}" title="Delete">&times;</button>
+                </div>
+            </div>
+        `).join('') : '<p class="git-info">No snippets yet. Click + to add one.</p>';
+
+        list.querySelectorAll('.snippet-insert').forEach(btn => {
+            btn.addEventListener('click', () => {
+                const s = snippets.find(sn => sn.id === btn.dataset.id);
+                if (s) onInsert(s.code);
+            });
+        });
+
+        list.querySelectorAll('.snippet-delete').forEach(btn => {
+            btn.addEventListener('click', async () => {
+                await deleteSnippet(btn.dataset.id);
+                loadSnippets();
+            });
+        });
+    }
+
+    document.getElementById('snippets-search')?.addEventListener('input', (e) => renderList(e.target.value));
+
+    document.getElementById('snippets-add')?.addEventListener('click', () => {
+        const name = prompt('Snippet name:');
+        if (!name) return;
+        const language = prompt('Language (e.g., javascript, python, html):') || 'text';
+        const code = prompt('Paste your code snippet:');
+        if (!code) return;
+
+        saveSnippet({ id: Date.now().toString(), name, language, code }).then(() => loadSnippets());
+    });
+
+    loadSnippets();
+}
+
+module.exports = { renderSnippetsPanel };

src/sidebar/templates-panel.js

@@ -0,0 +1,34 @@
+const fs = require('fs');
+const path = require('path');
+
+const templates = [
+    { name: 'Blog Post', file: 'blog-post.md', description: 'Article with frontmatter' },
+    { name: 'Meeting Notes', file: 'meeting-notes.md', description: 'Agenda, notes, action items' },
+    { name: 'Technical Spec', file: 'technical-spec.md', description: 'Requirements and architecture' },
+    { name: 'Changelog', file: 'changelog.md', description: 'Keep a Changelog format' },
+    { name: 'README', file: 'readme.md', description: 'Project documentation' },
+    { name: 'Project Plan', file: 'project-plan.md', description: 'Goals, milestones, timeline' },
+    { name: 'API Docs', file: 'api-docs.md', description: 'API endpoint documentation' },
+    { name: 'Tutorial', file: 'tutorial.md', description: 'Step-by-step guide' },
+    { name: 'Release Notes', file: 'release-notes.md', description: 'Version release summary' },
+    { name: 'Comparison', file: 'comparison.md', description: 'Feature comparison table' },
+];
+
+function renderTemplatesPanel(container, onSelect) {
+    container.innerHTML = `
+        <div class="panel-list">
+            ${templates.map(t => `
+                <div class="panel-list-item template-item" data-file="${t.file}">
+                    <div class="panel-list-item-title">${t.name}</div>
+                    <div class="panel-list-item-desc">${t.description}</div>
+                </div>
+            `).join('')}
+        </div>
+    `;
+
+    container.querySelectorAll('.template-item').forEach(el => {
+        el.addEventListener('click', () => onSelect(el.dataset.file));
+    });
+}
+
+module.exports = { renderTemplatesPanel, templates };

src/styles-modern.css

@@ -290,6 +290,20 @@ body {
   /* Color controlled by theme */
 }
 
+/* CodeMirror container */
+.codemirror-container {
+  height: 100%;
+  overflow: auto;
+}
+.codemirror-container .cm-editor {
+  height: 100%;
+  font-family: 'JetBrains Mono', 'Fira Code', 'Consolas', monospace;
+  font-size: 14px;
+}
+.codemirror-container .cm-scroller {
+  overflow: auto;
+}
+
 .pane:last-child {
   padding: 0;
   /* Background controlled by theme */
@@ -309,10 +323,12 @@ body {
   display: flex;
   justify-content: space-between;
   align-items: center;
-  padding: 8px 20px;
+  padding: 2px 12px;
   /* Background and color controlled by theme */
   font-size: 12px;
   font-weight: 500;
+  min-height: 24px;
+  flex-shrink: 0;
 }
 
 /* Preview Styles - Modern Typography */
@@ -2111,3 +2127,209 @@ body.theme-rosepine-dawn .batch-dialog-footer {
   background: #f2e9e1;
   border-top-color: #dfdad9;
 }
+
+/* ========================================
+   Command Palette (Ctrl+Shift+P)
+   ======================================== */
+.command-palette-overlay {
+    position: fixed;
+    top: 0;
+    left: 0;
+    right: 0;
+    bottom: 0;
+    background: rgba(0, 0, 0, 0.3);
+    z-index: 1000;
+    display: flex;
+    justify-content: center;
+    padding-top: 80px;
+}
+.command-palette-overlay.hidden {
+    display: none;
+}
+.command-palette {
+    width: 560px;
+    max-height: 400px;
+    background: #fff;
+    border-radius: 12px;
+    box-shadow: 0 16px 48px rgba(0, 0, 0, 0.2);
+    overflow: hidden;
+    display: flex;
+    flex-direction: column;
+}
+.command-palette-input {
+    width: 100%;
+    padding: 14px 18px;
+    border: none;
+    outline: none;
+    font-size: 15px;
+    border-bottom: 1px solid #e5e7eb;
+    font-family: inherit;
+}
+.command-palette-results {
+    overflow-y: auto;
+    max-height: 340px;
+}
+.command-item {
+    display: flex;
+    justify-content: space-between;
+    align-items: center;
+    padding: 10px 18px;
+    cursor: pointer;
+    font-size: 14px;
+}
+.command-item:hover,
+.command-item.selected {
+    background: #f3f4f6;
+}
+.command-label strong {
+    color: #5661b3;
+}
+.command-shortcut {
+    font-size: 12px;
+    color: #9ca3af;
+    background: #f3f4f6;
+    padding: 2px 8px;
+    border-radius: 4px;
+    font-family: 'JetBrains Mono', monospace;
+}
+
+/* Dark theme command palette */
+body[class*="dark"] .command-palette {
+    background: #1e1e1e;
+    border: 1px solid #333;
+}
+body[class*="dark"] .command-palette-input {
+    background: #1e1e1e;
+    color: #eee;
+    border-color: #333;
+}
+body[class*="dark"] .command-item:hover,
+body[class*="dark"] .command-item.selected {
+    background: #2d2d2d;
+}
+body[class*="dark"] .command-shortcut {
+    background: #333;
+    color: #888;
+}
+
+/* ========================================
+   Breadcrumb Bar
+   ======================================== */
+.breadcrumb-bar {
+    padding: 4px 12px;
+    font-size: 12px;
+    color: var(--gray-500, #6b7280);
+    border-bottom: 1px solid var(--gray-200, #e5e7eb);
+    white-space: nowrap;
+    overflow: hidden;
+    text-overflow: ellipsis;
+    flex-shrink: 0;
+    background: var(--gray-50, #f9fafb);
+    font-family: 'JetBrains Mono', monospace;
+}
+body[class*="dark"] .breadcrumb-bar {
+    background: #1a1a1a;
+    color: #888;
+    border-color: #333;
+}
+
+/* Print Preview Dialog */
+.print-preview-dialog {
+    width: 90vw;
+    max-width: 1200px;
+    height: 80vh;
+    display: flex;
+    flex-direction: column;
+}
+.print-preview-body {
+    display: flex;
+    flex: 1;
+    overflow: hidden;
+}
+.print-preview-sidebar {
+    width: 260px;
+    padding: 16px;
+    border-right: 1px solid var(--gray-200, #e5e7eb);
+    overflow-y: auto;
+    flex-shrink: 0;
+    display: flex;
+    flex-direction: column;
+    gap: 16px;
+}
+.print-preview-content {
+    flex: 1;
+    padding: 16px;
+    background: #e5e7eb;
+    display: flex;
+    justify-content: center;
+    overflow: auto;
+}
+.print-preview-content iframe {
+    box-shadow: 0 2px 8px rgba(0,0,0,0.15);
+    border-radius: 4px;
+}
+.print-option-group {
+    display: flex;
+    flex-direction: column;
+    gap: 6px;
+}
+.print-option-group label {
+    font-size: 13px;
+    font-weight: 500;
+    color: var(--gray-600, #4b5563);
+}
+.print-option-group select,
+.print-option-group input[type="text"] {
+    padding: 8px 10px;
+    border: 1px solid var(--gray-300, #d1d5db);
+    border-radius: 8px;
+    font-size: 13px;
+    background: white;
+}
+.scale-control {
+    display: flex;
+    align-items: center;
+    gap: 8px;
+}
+.scale-control input[type="range"] {
+    flex: 1;
+}
+.checkbox-label {
+    display: flex;
+    align-items: center;
+    gap: 8px;
+    cursor: pointer;
+}
+.print-range-input {
+    margin-top: 6px;
+}
+.print-actions {
+    display: flex;
+    gap: 8px;
+    margin-top: auto;
+    padding-top: 16px;
+}
+.btn-primary {
+    flex: 1;
+    padding: 10px;
+    background: var(--primary-dark, #5661b3);
+    color: white;
+    border: none;
+    border-radius: 8px;
+    font-size: 14px;
+    font-weight: 500;
+    cursor: pointer;
+}
+.btn-primary:hover {
+    opacity: 0.9;
+}
+.btn-secondary {
+    flex: 1;
+    padding: 10px;
+    background: var(--gray-100, #f3f4f6);
+    color: var(--gray-700, #374151);
+    border: 1px solid var(--gray-300, #d1d5db);
+    border-radius: 8px;
+    font-size: 14px;
+    cursor: pointer;
+}

src/styles-sidebar.css

@@ -0,0 +1,268 @@
+/* Sidebar */
+.main-content {
+    display: flex;
+    flex: 1;
+    overflow: hidden;
+    min-height: 0;
+}
+
+.sidebar {
+    display: flex;
+    flex-shrink: 0;
+    height: 100%;
+    transition: width 0.2s ease;
+}
+
+.sidebar.collapsed {
+    width: 48px;
+}
+
+.sidebar:not(.collapsed) {
+    width: 328px; /* 48px icons + 280px panel */
+}
+
+.sidebar-icons {
+    display: flex;
+    flex-direction: column;
+    width: 48px;
+    background: var(--gray-100, #f3f4f6);
+    border-right: 1px solid var(--gray-200, #e5e7eb);
+    padding: 8px 0;
+    gap: 4px;
+    align-items: center;
+}
+
+.sidebar-icon {
+    width: 36px;
+    height: 36px;
+    display: flex;
+    align-items: center;
+    justify-content: center;
+    border: none;
+    background: transparent;
+    border-radius: 8px;
+    cursor: pointer;
+    color: var(--gray-500, #6b7280);
+    transition: all 0.15s ease;
+}
+
+.sidebar-icon:hover {
+    background: var(--gray-200, #e5e7eb);
+    color: var(--gray-700, #374151);
+}
+
+.sidebar-icon.active {
+    background: var(--gray-200, #e5e7eb);
+    color: var(--primary-dark, #5661b3);
+    box-shadow: inset 3px 0 0 var(--primary-dark, #5661b3);
+}
+
+.sidebar-panel {
+    width: 280px;
+    background: var(--gray-50, #f9fafb);
+    border-right: 1px solid var(--gray-200, #e5e7eb);
+    display: flex;
+    flex-direction: column;
+    overflow: hidden;
+}
+
+.sidebar.collapsed .sidebar-panel {
+    display: none;
+}
+
+.sidebar-panel-header {
+    display: flex;
+    align-items: center;
+    justify-content: space-between;
+    padding: 12px 16px;
+    border-bottom: 1px solid var(--gray-200, #e5e7eb);
+    font-weight: 600;
+    font-size: 13px;
+    text-transform: uppercase;
+    letter-spacing: 0.05em;
+    color: var(--gray-600, #4b5563);
+}
+
+.sidebar-panel-close {
+    background: none;
+    border: none;
+    font-size: 18px;
+    cursor: pointer;
+    color: var(--gray-400, #9ca3af);
+    padding: 0 4px;
+    border-radius: 4px;
+}
+
+.sidebar-panel-close:hover {
+    background: var(--gray-200, #e5e7eb);
+    color: var(--gray-600, #4b5563);
+}
+
+.sidebar-panel-content {
+    flex: 1;
+    overflow-y: auto;
+    padding: 12px;
+}
+
+/* Dark theme support */
+body[class*="dark"] .sidebar-icons,
+body[class*="dark"] .sidebar-panel {
+    background: #1e1e1e;
+    border-color: #333;
+}
+
+body[class*="dark"] .sidebar-icon {
+    color: #888;
+}
+
+body[class*="dark"] .sidebar-icon:hover {
+    background: #333;
+    color: #ccc;
+}
+
+body[class*="dark"] .sidebar-icon.active {
+    background: #333;
+    color: #8b9aff;
+    box-shadow: inset 3px 0 0 #8b9aff;
+}
+
+body[class*="dark"] .sidebar-panel-header {
+    border-color: #333;
+    color: #ccc;
+}
+
+/* Panel list items (templates, etc.) */
+.panel-list-item {
+    padding: 10px 12px;
+    border-radius: 6px;
+    cursor: pointer;
+    margin-bottom: 4px;
+}
+.panel-list-item:hover {
+    background: var(--gray-200, #e5e7eb);
+}
+.panel-list-item-title {
+    font-size: 13px;
+    font-weight: 500;
+    color: var(--gray-800, #1f2937);
+}
+.panel-list-item-desc {
+    font-size: 11px;
+    color: var(--gray-500, #6b7280);
+    margin-top: 2px;
+}
+
+body[class*="dark"] .panel-list-item:hover {
+    background: #333;
+}
+body[class*="dark"] .panel-list-item-title {
+    color: #ddd;
+}
+body[class*="dark"] .panel-list-item-desc {
+    color: #888;
+}
+
+/* Explorer Panel */
+.explorer-toolbar {
+    display: flex;
+    gap: 4px;
+    margin-bottom: 8px;
+}
+.explorer-path {
+    flex: 1;
+    padding: 6px 8px;
+    border: 1px solid var(--gray-300, #d1d5db);
+    border-radius: 6px;
+    font-size: 12px;
+    background: white;
+    overflow: hidden;
+    text-overflow: ellipsis;
+}
+.explorer-browse-btn {
+    border: 1px solid var(--gray-300, #d1d5db);
+    border-radius: 6px;
+    background: white;
+    cursor: pointer;
+    padding: 4px 8px;
+}
+.tree-item {
+    padding: 3px 0;
+    cursor: pointer;
+    font-size: 13px;
+    user-select: none;
+}
+.tree-item:hover {
+    background: var(--gray-100, #f3f4f6);
+    border-radius: 4px;
+}
+.tree-icon {
+    margin-right: 4px;
+    font-size: 12px;
+}
+.tree-children {
+    padding-left: 16px;
+}
+.tree-folder.collapsed .tree-children {
+    display: none;
+}
+.tree-name {
+    font-size: 13px;
+}
+
+/* Git Panel */
+.git-section { margin-bottom: 16px; }
+.git-section-title { font-size: 11px; text-transform: uppercase; letter-spacing: 0.05em; color: var(--gray-500); margin-bottom: 8px; }
+.git-file { display: flex; align-items: center; padding: 4px 6px; border-radius: 4px; font-size: 13px; gap: 6px; }
+.git-file:hover { background: var(--gray-100, #f3f4f6); }
+.git-file-status { font-weight: 700; font-family: monospace; width: 16px; text-align: center; }
+.git-file-name { flex: 1; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
+.git-stage-btn { border: none; background: var(--gray-200); border-radius: 4px; cursor: pointer; font-size: 14px; width: 22px; height: 22px; }
+.git-commit-input { width: 100%; padding: 8px; border: 1px solid var(--gray-300); border-radius: 6px; font-size: 13px; font-family: inherit; resize: vertical; box-sizing: border-box; }
+.git-commit-btn { width: 100%; margin-top: 8px; padding: 8px; background: var(--primary-dark, #5661b3); color: white; border: none; border-radius: 6px; font-size: 13px; cursor: pointer; }
+.git-commit-btn:hover { opacity: 0.9; }
+.git-log-entry { padding: 6px 0; border-bottom: 1px solid var(--gray-100); }
+.git-log-msg { font-size: 13px; }
+.git-log-meta { font-size: 11px; color: var(--gray-500); margin-top: 2px; }
+.git-info { font-size: 13px; color: var(--gray-500); padding: 8px 0; }
+.git-loading { font-size: 13px; color: var(--gray-400); }
+
+/* Snippets Panel */
+.snippets-toolbar { display: flex; gap: 4px; margin-bottom: 8px; }
+.snippets-search { flex: 1; padding: 6px 10px; border: 1px solid var(--gray-300); border-radius: 6px; font-size: 13px; }
+.snippets-add-btn { width: 32px; border: 1px solid var(--gray-300); border-radius: 6px; background: white; font-size: 18px; cursor: pointer; }
+.snippet-item { padding: 8px; border: 1px solid var(--gray-200); border-radius: 6px; margin-bottom: 6px; }
+.snippet-header { display: flex; justify-content: space-between; align-items: center; margin-bottom: 4px; }
+.snippet-name { font-size: 13px; font-weight: 500; }
+.snippet-lang { font-size: 11px; background: var(--gray-100); padding: 2px 6px; border-radius: 4px; color: var(--gray-500); }
+.snippet-preview { font-size: 12px; background: var(--gray-50); padding: 6px; border-radius: 4px; margin: 4px 0; overflow: hidden; max-height: 60px; }
+.snippet-preview code { font-family: 'JetBrains Mono', monospace; }
+.snippet-actions { display: flex; gap: 4px; }
+.snippet-insert { font-size: 12px; padding: 4px 8px; border: 1px solid var(--gray-300); border-radius: 4px; background: white; cursor: pointer; }
+.snippet-delete { font-size: 14px; padding: 4px 8px; border: 1px solid var(--gray-300); border-radius: 4px; background: white; cursor: pointer; color: #ef4444; }
+
+/* Dark theme for sidebar panels */
+body[class*="dark"] .explorer-path,
+body[class*="dark"] .explorer-browse-btn,
+body[class*="dark"] .snippets-search,
+body[class*="dark"] .snippets-add-btn,
+body[class*="dark"] .snippet-insert,
+body[class*="dark"] .snippet-delete {
+    background: #2d2d2d;
+    border-color: #444;
+    color: #ccc;
+}
+body[class*="dark"] .git-commit-input {
+    background: #2d2d2d;
+    border-color: #444;
+    color: #ccc;
+}
+body[class*="dark"] .snippet-item {
+    border-color: #444;
+}
+body[class*="dark"] .snippet-preview {
+    background: #2d2d2d;
+}
+body[class*="dark"] .tree-item:hover,
+body[class*="dark"] .git-file:hover {
+    background: #333;
+}

src/styles-welcome.css

@@ -0,0 +1,24 @@
+.welcome-container { padding: 40px; max-width: 900px; margin: 0 auto; }
+.welcome-hero { text-align: center; margin-bottom: 40px; }
+.welcome-title { font-size: 32px; font-weight: 700; color: var(--gray-800, #1f2937); }
+.welcome-version { font-size: 14px; color: var(--primary-dark, #5661b3); margin-top: 4px; font-weight: 500; }
+.welcome-subtitle { font-size: 16px; color: var(--gray-500, #6b7280); margin-top: 8px; }
+.welcome-grid { display: grid; gap: 32px; }
+.welcome-section h2 { font-size: 18px; margin-bottom: 16px; color: var(--gray-700, #374151); }
+.welcome-cards { display: grid; grid-template-columns: repeat(auto-fit, minmax(180px, 1fr)); gap: 12px; }
+.welcome-card { padding: 20px; border: 1px solid var(--gray-200, #e5e7eb); border-radius: 12px; cursor: pointer; text-align: center; transition: all 0.2s; }
+.welcome-card:hover { border-color: var(--primary-dark, #5661b3); box-shadow: 0 4px 12px rgba(0,0,0,0.08); transform: translateY(-2px); }
+.welcome-card-icon { font-size: 28px; margin-bottom: 8px; }
+.welcome-card h3 { font-size: 15px; margin-bottom: 4px; }
+.welcome-card p { font-size: 13px; color: var(--gray-500); }
+.welcome-card kbd { display: inline-block; margin-top: 8px; padding: 2px 8px; background: var(--gray-100); border: 1px solid var(--gray-300); border-radius: 4px; font-size: 12px; font-family: 'JetBrains Mono', monospace; }
+.welcome-features { list-style: none; padding: 0; }
+.welcome-features li { padding: 6px 0; font-size: 14px; border-bottom: 1px solid var(--gray-100, #f3f4f6); }
+.welcome-features strong { color: var(--primary-dark, #5661b3); }
+.welcome-recent-item { padding: 8px 12px; border-radius: 6px; cursor: pointer; margin-bottom: 4px; }
+.welcome-recent-item:hover { background: var(--gray-100); }
+.welcome-recent-name { font-size: 14px; font-weight: 500; display: block; }
+.welcome-recent-path { font-size: 12px; color: var(--gray-500); display: block; margin-top: 2px; overflow: hidden; text-overflow: ellipsis; }
+.welcome-muted { color: var(--gray-400); font-size: 14px; }
+.welcome-footer { margin-top: 32px; text-align: center; }
+.welcome-checkbox { font-size: 13px; color: var(--gray-500); cursor: pointer; }

src/styles.css

@@ -139,11 +139,18 @@ body {
     background: #d0d0d0;
 }
 
+.toolbar-group {
+    display: flex;
+    align-items: center;
+    gap: 2px;
+}
 .toolbar-separator {
     width: 1px;
-    height: 24px;
-    background: #ccc;
-    margin: 0 8px;
+    height: 20px;
+    background: rgba(0, 0, 0, 0.12);
+    margin: 0 6px;
+    align-self: center;
+    flex-shrink: 0;
 }
 
 /* Editor Container */
@@ -181,34 +188,6 @@ body {
     background: #666;
 }
 
-/* Preview Header */
-.preview-header {
-    display: flex;
-    justify-content: flex-end;
-    align-items: center;
-    padding: 4px 8px;
-    background: #f6f8fa;
-    border-bottom: 1px solid #dfe2e5;
-    min-height: 32px;
-}
-
-.preview-popout-btn {
-    background: transparent;
-    border: none;
-    border-radius: 3px;
-    padding: 2px 6px;
-    cursor: pointer;
-    font-size: 11px;
-    color: #8c959f;
-    opacity: 0.5;
-    transition: all 0.2s;
-}
-
-.preview-popout-btn:hover {
-    background: rgba(0, 0, 0, 0.05);
-    opacity: 1;
-    color: #24292f;
-}
 
 .editor-textarea {
     width: 100%;
@@ -222,6 +201,20 @@ body {
     resize: none;
 }
 
+/* CodeMirror container */
+.codemirror-container {
+    height: 100%;
+    overflow: auto;
+}
+.codemirror-container .cm-editor {
+    height: 100%;
+    font-family: 'JetBrains Mono', 'Fira Code', 'Consolas', monospace;
+    font-size: 14px;
+}
+.codemirror-container .cm-scroller {
+    overflow: auto;
+}
+
 .pane:last-child {
     padding: 0;
     background: #fff;
@@ -269,15 +262,67 @@ body {
     line-height: 1.6;
 }
 
+/* Bottom Panel (REPL Output) */
+.bottom-panel { display: flex; flex-direction: column; border-top: 1px solid var(--gray-200, #e5e7eb); flex-shrink: 0; }
+.bottom-panel.collapsed { height: 0; overflow: hidden; border: none; }
+.bottom-panel:not(.collapsed) { height: 200px; }
+.bottom-panel-header { display: flex; justify-content: space-between; align-items: center; padding: 6px 12px; background: var(--gray-50, #f9fafb); border-bottom: 1px solid var(--gray-200); }
+.bottom-panel-title { font-size: 13px; font-weight: 600; color: var(--gray-600); }
+.bottom-panel-actions { display: flex; gap: 4px; }
+.bottom-panel-btn { font-size: 12px; padding: 4px 8px; border: 1px solid var(--gray-300); border-radius: 4px; background: white; cursor: pointer; }
+.bottom-panel-content { flex: 1; overflow-y: auto; padding: 12px; font-family: 'JetBrains Mono', monospace; font-size: 13px; background: #1e1e1e; color: #d4d4d4; }
+.repl-entry { margin-bottom: 8px; }
+.repl-command { color: #569cd6; margin-bottom: 2px; }
+.repl-stdout { color: #d4d4d4; white-space: pre-wrap; }
+.repl-stderr { color: #f44747; white-space: pre-wrap; }
+.repl-error { color: #f44747; }
+
+/* Code Run Button */
+.code-run-btn {
+    position: absolute;
+    top: 6px;
+    right: 6px;
+    padding: 4px 10px;
+    font-size: 12px;
+    background: var(--primary-dark, #5661b3);
+    color: white;
+    border: none;
+    border-radius: 4px;
+    cursor: pointer;
+    opacity: 0;
+    transition: opacity 0.2s;
+}
+pre:hover .code-run-btn { opacity: 1; }
+
+/* Dark theme bottom panel */
+body[class*="dark"] .bottom-panel-header { background: #1e1e1e; border-color: #333; }
+body[class*="dark"] .bottom-panel-btn { background: #2d2d2d; border-color: #444; color: #ccc; }
+body[class*="dark"] .bottom-panel-title { color: #ccc; }
+
 /* Status Bar */
 .status-bar {
     display: flex;
     justify-content: space-between;
-    padding: 4px 12px;
+    align-items: center;
+    padding: 2px 12px;
     background: #f5f5f5;
     border-top: 1px solid #ddd;
     font-size: 12px;
     color: #666;
+    min-height: 24px;
+    flex-shrink: 0;
+}
+.status-bar-left, .status-bar-right {
+    display: flex;
+    align-items: center;
+    gap: 4px;
+}
+.status-separator {
+    color: var(--gray-300, #d1d5db);
+    margin: 0 2px;
+}
+.status-item {
+    white-space: nowrap;
 }
 
 /* Preview Styles */
@@ -3973,108 +4018,43 @@ body.theme-github .mermaid {
     border-color: #e1e4e8;
 }
 
+/* Task List Styles */
+.preview-content input[type="checkbox"] {
+    margin-right: 6px;
+    pointer-events: none;
+}
+.preview-content li.task-list-item {
+    list-style: none;
+    margin-left: -20px;
+}
+
+/* Admonition Styles */
+.admonition {
+    border-left: 4px solid;
+    border-radius: 4px;
+    padding: 12px 16px;
+    margin: 16px 0;
+}
+.admonition-title {
+    font-weight: 600;
+    margin-bottom: 8px;
+}
+.admonition-note, .admonition-info { border-color: #3b82f6; background: #eff6ff; }
+.admonition-warning { border-color: #f59e0b; background: #fffbeb; }
+.admonition-tip { border-color: #10b981; background: #ecfdf5; }
+.admonition-danger { border-color: #ef4444; background: #fef2f2; }
+
+/* TOC Styles */
+.toc { background: #f9fafb; border: 1px solid #e5e7eb; border-radius: 8px; padding: 16px; margin: 16px 0; }
+.toc h2 { font-size: 14px; margin-bottom: 8px; }
+.toc ul { list-style: none; padding: 0; }
+.toc li { padding: 2px 0; }
+.toc .toc-h1 { padding-left: 0; }
+.toc .toc-h2 { padding-left: 16px; }
+.toc .toc-h3 { padding-left: 32px; }
+.toc .toc-h4 { padding-left: 48px; }
+.toc a { color: #5661b3; text-decoration: none; }
+.toc a:hover { text-decoration: underline; }
+
 /* Command Palette Styles */
-.command-palette {
-    position: fixed;
-    top: 0;
-    left: 0;
-    right: 0;
-    bottom: 0;
-    background: rgba(0, 0, 0, 0.7);
-    display: flex;
-    align-items: flex-start;
-    justify-content: center;
-    padding-top: 100px;
-    z-index: 10000;
-}
-
-.command-palette.hidden {
-    display: none;
-}
-
-.command-palette-content {
-    background: #fff;
-    border-radius: 12px;
-    width: 600px;
-    max-width: 90%;
-    box-shadow: 0 20px 60px rgba(0, 0, 0, 0.3);
-    overflow: hidden;
-}
-
-#command-search {
-    width: 100%;
-    padding: 20px;
-    font-size: 18px;
-    border: none;
-    border-bottom: 1px solid #e0e0e0;
-    outline: none;
-}
-
-.command-list {
-    max-height: 400px;
-    overflow-y: auto;
-}
-
-.command-item {
-    padding: 12px 20px;
-    cursor: pointer;
-    display: flex;
-    justify-content: space-between;
-    align-items: center;
-    transition: background 0.15s;
-}
-
-.command-item:hover,
-.command-item.selected {
-    background: #f0f0f0;
-}
-
-.command-name {
-    font-weight: 500;
-}
-
-.command-shortcut {
-    font-size: 12px;
-    color: #666;
-    background: #f5f5f5;
-    padding: 3px 8px;
-    border-radius: 3px;
-}
-
-.command-palette-footer {
-    padding: 12px 20px;
-    background: #f9f9f9;
-    border-top: 1px solid #e0e0e0;
-    display: flex;
-    gap: 20px;
-    font-size: 12px;
-    color: #666;
-}
-
-/* Dark theme support for command palette */
-body.theme-dark .command-palette-content {
-    background: #2d2d2d;
-    color: #f0f0f0;
-}
-
-body.theme-dark #command-search {
-    background: #2d2d2d;
-    color: #f0f0f0;
-    border-color: #444;
-}
-
-body.theme-dark .command-item:hover,
-body.theme-dark .command-item.selected {
-    background: #3d3d3d;
-}
-
-body.theme-dark .command-shortcut {
-    background: #3d3d3d;
-    color: #ccc;
-}
-
-body.theme-dark .command-palette-footer {
-    background: #252525;
-    border-color: #444;
-    color: #999;
-}
+/* Command Palette styles moved to styles-modern.css */

src/templates/api-docs.md

@@ -0,0 +1,90 @@
+# API Documentation
+
+**Base URL:** `https://api.example.com/v1`
+**Version:** 1.0
+**Date:** {{DATE}}
+
+## Authentication
+
+All requests require an API key in the header:
+
+```
+Authorization: Bearer YOUR_API_KEY
+```
+
+## Endpoints
+
+### Get All Resources
+
+```
+GET /resources
+```
+
+**Query Parameters:**
+
+| Parameter | Type | Required | Description |
+|-----------|------|----------|-------------|
+| page | integer | No | Page number (default: 1) |
+| limit | integer | No | Items per page (default: 20) |
+
+**Response:**
+
+```json
+{
+  "data": [],
+  "total": 0,
+  "page": 1
+}
+```
+
+### Get Resource by ID
+
+```
+GET /resources/:id
+```
+
+**Response:**
+
+```json
+{
+  "id": "1",
+  "name": "Resource name",
+  "created_at": "2024-01-01T00:00:00Z"
+}
+```
+
+### Create Resource
+
+```
+POST /resources
+```
+
+**Request Body:**
+
+```json
+{
+  "name": "New resource",
+  "description": "Description"
+}
+```
+
+### Update Resource
+
+```
+PUT /resources/:id
+```
+
+### Delete Resource
+
+```
+DELETE /resources/:id
+```
+
+## Error Codes
+
+| Code | Description |
+|------|-------------|
+| 400 | Bad Request |
+| 401 | Unauthorized |
+| 404 | Not Found |
+| 500 | Internal Server Error |

src/templates/blog-post.md

@@ -0,0 +1,20 @@
+---
+title: Blog Post Title
+date: {{DATE}}
+author: Your Name
+tags: []
+---
+
+# Blog Post Title
+
+## Introduction
+
+Write your introduction here.
+
+## Main Content
+
+Your main content goes here.
+
+## Conclusion
+
+Wrap up your thoughts.

src/templates/changelog.md

@@ -0,0 +1,20 @@
+# Changelog
+
+## [Unreleased]
+
+### Added
+- New feature
+
+### Changed
+- Updated feature
+
+### Fixed
+- Bug fix
+
+### Removed
+- Removed feature
+
+## [1.0.0] - {{DATE}}
+
+### Added
+- Initial release

src/templates/comparison.md

@@ -0,0 +1,59 @@
+# Comparison: [Option A] vs [Option B]
+
+**Date:** {{DATE}}
+**Author:** Your Name
+
+## Overview
+
+Brief description of what is being compared and why.
+
+## Feature Comparison
+
+| Feature | Option A | Option B |
+|---------|----------|----------|
+| Feature 1 | Yes | Yes |
+| Feature 2 | Yes | No |
+| Feature 3 | No | Yes |
+| Feature 4 | Partial | Yes |
+
+## Pricing
+
+| Plan | Option A | Option B |
+|------|----------|----------|
+| Free | Limited | Limited |
+| Pro | $10/mo | $15/mo |
+| Enterprise | Custom | Custom |
+
+## Pros and Cons
+
+### Option A
+
+**Pros:**
+- Pro 1
+- Pro 2
+
+**Cons:**
+- Con 1
+- Con 2
+
+### Option B
+
+**Pros:**
+- Pro 1
+- Pro 2
+
+**Cons:**
+- Con 1
+- Con 2
+
+## Performance
+
+| Metric | Option A | Option B |
+|--------|----------|----------|
+| Speed | Fast | Moderate |
+| Memory | Low | Medium |
+| Scalability | Good | Excellent |
+
+## Recommendation
+
+Based on the analysis above, [Option A/B] is recommended for [use case] because [reason].

src/templates/meeting-notes.md

@@ -0,0 +1,26 @@
+# Meeting Notes
+
+**Date:** {{DATE}}
+**Attendees:**
+- Name 1
+- Name 2
+
+## Agenda
+
+1. Topic 1
+2. Topic 2
+
+## Discussion
+
+### Topic 1
+
+Notes here.
+
+## Action Items
+
+- [ ] Action item 1 — Owner — Due date
+- [ ] Action item 2 — Owner — Due date
+
+## Next Meeting
+
+Date: TBD

src/templates/project-plan.md

@@ -0,0 +1,54 @@
+# Project Plan: [Project Name]
+
+**Date:** {{DATE}}
+**Project Lead:** Your Name
+**Status:** Planning
+
+## Goals
+
+1. Primary goal
+2. Secondary goal
+
+## Scope
+
+### In Scope
+- Item 1
+- Item 2
+
+### Out of Scope
+- Item 1
+
+## Milestones
+
+| Milestone | Target Date | Status |
+|-----------|-------------|--------|
+| Kickoff | {{DATE}} | Not Started |
+| MVP | TBD | Not Started |
+| Launch | TBD | Not Started |
+
+## Resources
+
+| Role | Person | Allocation |
+|------|--------|------------|
+| Lead | Name | 100% |
+| Developer | Name | 50% |
+
+## Risks
+
+| Risk | Impact | Likelihood | Mitigation |
+|------|--------|------------|------------|
+| Risk 1 | High | Medium | Plan |
+
+## Timeline
+
+### Phase 1: Planning
+- [ ] Define requirements
+- [ ] Create design documents
+
+### Phase 2: Development
+- [ ] Implement core features
+- [ ] Write tests
+
+### Phase 3: Launch
+- [ ] Deploy to production
+- [ ] Monitor and iterate

src/templates/readme.md

@@ -0,0 +1,38 @@
+# Project Name
+
+Brief description of the project.
+
+## Features
+
+- Feature 1
+- Feature 2
+
+## Installation
+
+```bash
+npm install project-name
+```
+
+## Usage
+
+```javascript
+const project = require('project-name');
+```
+
+## Configuration
+
+| Option | Default | Description |
+|--------|---------|-------------|
+| option1 | true | Description |
+
+## Contributing
+
+1. Fork the repository
+2. Create your feature branch
+3. Commit your changes
+4. Push to the branch
+5. Open a Pull Request
+
+## License
+
+MIT

src/templates/release-notes.md

@@ -0,0 +1,42 @@
+# Release Notes - v1.0.0
+
+**Release Date:** {{DATE}}
+
+## Highlights
+
+Brief summary of the most important changes in this release.
+
+## New Features
+
+- **Feature 1:** Description of the new feature
+- **Feature 2:** Description of the new feature
+
+## Improvements
+
+- Improved performance of feature X
+- Updated dependency Y to version Z
+
+## Bug Fixes
+
+- Fixed issue where X would cause Y (#123)
+- Resolved crash when performing Z (#456)
+
+## Breaking Changes
+
+- Changed API endpoint from `/old` to `/new`
+- Removed deprecated method `oldMethod()`
+
+## Migration Guide
+
+### From v0.9.x to v1.0.0
+
+1. Update configuration file format
+2. Replace deprecated API calls
+
+## Known Issues
+
+- Issue description (#789)
+
+## Contributors
+
+Thanks to everyone who contributed to this release.

src/templates/technical-spec.md

@@ -0,0 +1,42 @@
+# Technical Specification: [Feature Name]
+
+**Version:** 1.0
+**Date:** {{DATE}}
+**Author:** Your Name
+**Status:** Draft
+
+## Overview
+
+Brief description of what this feature does.
+
+## Requirements
+
+### Functional Requirements
+1. Requirement 1
+2. Requirement 2
+
+### Non-Functional Requirements
+1. Performance requirement
+2. Security requirement
+
+## Architecture
+
+Describe the technical approach.
+
+## API Design
+
+### Endpoints
+
+| Method | Path | Description |
+|--------|------|-------------|
+| GET | /api/resource | Get resource |
+
+## Testing Strategy
+
+Describe how this will be tested.
+
+## Timeline
+
+| Phase | Duration | Deliverables |
+|-------|----------|-------------|
+| Phase 1 | 1 week | Core implementation |

src/templates/tutorial.md

@@ -0,0 +1,71 @@
+# Tutorial: [Topic Name]
+
+**Date:** {{DATE}}
+**Difficulty:** Beginner / Intermediate / Advanced
+**Time:** ~30 minutes
+
+## Prerequisites
+
+- Prerequisite 1
+- Prerequisite 2
+
+## What You Will Learn
+
+- Learning objective 1
+- Learning objective 2
+
+## Step 1: Getting Started
+
+Description of the first step.
+
+```bash
+# Example command
+echo "Hello, World!"
+```
+
+## Step 2: Core Concepts
+
+Explain the main concepts here.
+
+### Key Concept A
+
+Details about concept A.
+
+### Key Concept B
+
+Details about concept B.
+
+## Step 3: Building the Feature
+
+Walk through the implementation.
+
+```javascript
+// Example code
+function example() {
+    return 'Hello';
+}
+```
+
+## Step 4: Testing
+
+How to verify everything works.
+
+## Common Issues
+
+### Issue 1
+**Problem:** Description of the problem.
+**Solution:** How to fix it.
+
+### Issue 2
+**Problem:** Description of the problem.
+**Solution:** How to fix it.
+
+## Next Steps
+
+- Suggested follow-up 1
+- Suggested follow-up 2
+
+## Resources
+
+- [Resource 1](https://example.com)
+- [Resource 2](https://example.com)

src/welcome.js

@@ -0,0 +1,78 @@
+function createWelcomeContent(recentFiles = []) {
+    const recentHtml = recentFiles.length
+        ? recentFiles.map(f => {
+            const name = f.split(/[/\\]/).pop();
+            return `<div class="welcome-recent-item" data-path="${f}"><span class="welcome-recent-name">${name}</span><span class="welcome-recent-path">${f}</span></div>`;
+        }).join('')
+        : '<p class="welcome-muted">No recent files</p>';
+
+    return `
+    <div class="welcome-container">
+        <div class="welcome-hero">
+            <h1 class="welcome-title">MarkdownConverter</h1>
+            <p class="welcome-version">Version 4.0.0</p>
+            <p class="welcome-subtitle">Professional Markdown Editor & Universal Document Converter</p>
+        </div>
+
+        <div class="welcome-grid">
+            <div class="welcome-section">
+                <h2>Quick Start</h2>
+                <div class="welcome-cards">
+                    <div class="welcome-card" data-action="new-file">
+                        <div class="welcome-card-icon">+</div>
+                        <h3>New Document</h3>
+                        <p>Create a blank document</p>
+                        <kbd>Ctrl+N</kbd>
+                    </div>
+                    <div class="welcome-card" data-action="open-file">
+                        <div class="welcome-card-icon">&#128194;</div>
+                        <h3>Open File</h3>
+                        <p>Open an existing file</p>
+                        <kbd>Ctrl+O</kbd>
+                    </div>
+                    <div class="welcome-card" data-action="open-template">
+                        <div class="welcome-card-icon">&#128203;</div>
+                        <h3>From Template</h3>
+                        <p>Start from a template</p>
+                    </div>
+                    <div class="welcome-card" data-action="command-palette">
+                        <div class="welcome-card-icon">&#8984;</div>
+                        <h3>Command Palette</h3>
+                        <p>Search all actions</p>
+                        <kbd>Ctrl+Shift+P</kbd>
+                    </div>
+                </div>
+            </div>
+
+            <div class="welcome-section">
+                <h2>What's New in v4.0.0</h2>
+                <ul class="welcome-features">
+                    <li><strong>CodeMirror Editor</strong> — Syntax highlighting, code folding, multiple cursors</li>
+                    <li><strong>Sidebar Panels</strong> — File Explorer, Git, Snippets, Templates</li>
+                    <li><strong>Command Palette</strong> — Quick access to all actions</li>
+                    <li><strong>Code Execution</strong> — Run JS, Python, Bash from code blocks</li>
+                    <li><strong>Print Preview</strong> — Full print customization dialog</li>
+                    <li><strong>New Formats</strong> — Reveal.js, YAML, JSON, Confluence, and more</li>
+                    <li><strong>Spell Checking</strong> — System dictionary with suggestions</li>
+                    <li><strong>Markdown Extensions</strong> — Footnotes, admonitions, TOC</li>
+                    <li><strong>Image Handling</strong> — Paste and drag-drop images</li>
+                    <li><strong>PlantUML</strong> — Diagram rendering in preview</li>
+                </ul>
+            </div>
+
+            <div class="welcome-section">
+                <h2>Recent Files</h2>
+                <div class="welcome-recent">${recentHtml}</div>
+            </div>
+        </div>
+
+        <div class="welcome-footer">
+            <label class="welcome-checkbox">
+                <input type="checkbox" id="show-welcome-startup" checked>
+                Show this tab on startup
+            </label>
+        </div>
+    </div>`;
+}
+
+module.exports = { createWelcomeContent };

tests/command-palette.test.js

@@ -0,0 +1,144 @@
+/**
+ * @jest-environment jsdom
+ */
+
+/**
+ * Tests for CommandPalette
+ * Tests command registration, filtering, execution, and keyboard navigation
+ */
+
+describe('CommandPalette', () => {
+    let CommandPalette;
+
+    beforeEach(() => {
+        document.body.innerHTML = `
+            <div class="command-palette-overlay hidden" id="command-palette-overlay">
+                <div class="command-palette">
+                    <input type="text" id="command-palette-input">
+                    <div id="command-palette-results"></div>
+                </div>
+            </div>
+        `;
+        CommandPalette = require('../src/command-palette').CommandPalette;
+    });
+
+    test('starts hidden', () => {
+        const palette = new CommandPalette();
+        expect(palette.isOpen()).toBe(false);
+    });
+
+    test('opens and focuses input', () => {
+        const palette = new CommandPalette();
+        palette.open();
+        expect(palette.isOpen()).toBe(true);
+    });
+
+    test('closes', () => {
+        const palette = new CommandPalette();
+        palette.open();
+        palette.close();
+        expect(palette.isOpen()).toBe(false);
+    });
+
+    test('registers and renders commands', () => {
+        const palette = new CommandPalette();
+        palette.register('Test Command', 'Ctrl+T', () => {});
+        palette.register('Another Command', '', () => {});
+        palette.open();
+        const items = document.querySelectorAll('.command-item');
+        expect(items.length).toBe(2);
+    });
+
+    test('filters commands by search', () => {
+        const palette = new CommandPalette();
+        palette.register('Save File', 'Ctrl+S', () => {});
+        palette.register('Open File', 'Ctrl+O', () => {});
+        palette.register('Bold Text', 'Ctrl+B', () => {});
+        palette.renderResults('file');
+        const items = document.querySelectorAll('.command-item');
+        expect(items.length).toBe(2);
+    });
+
+    test('executes command', () => {
+        const palette = new CommandPalette();
+        const action = jest.fn();
+        palette.register('Test', '', action);
+        palette.open();
+        palette.executeSelected();
+        expect(action).toHaveBeenCalled();
+    });
+
+    test('highlights matching text', () => {
+        const palette = new CommandPalette();
+        const result = palette.highlightMatch('Save File', 'save');
+        expect(result).toContain('<strong>');
+        expect(result).toContain('Save');
+    });
+
+    test('highlightMatch returns original text when no query', () => {
+        const palette = new CommandPalette();
+        const result = palette.highlightMatch('Save File', '');
+        expect(result).toBe('Save File');
+    });
+
+    test('filters case-insensitively', () => {
+        const palette = new CommandPalette();
+        palette.register('Save File', '', () => {});
+        palette.register('Open File', '', () => {});
+        palette.renderResults('SAVE');
+        const items = document.querySelectorAll('.command-item');
+        expect(items.length).toBe(1);
+    });
+
+    test('shows all commands when query is empty', () => {
+        const palette = new CommandPalette();
+        palette.register('Cmd1', '', () => {});
+        palette.register('Cmd2', '', () => {});
+        palette.register('Cmd3', '', () => {});
+        palette.renderResults('');
+        const items = document.querySelectorAll('.command-item');
+        expect(items.length).toBe(3);
+    });
+
+    test('displays shortcut when provided', () => {
+        const palette = new CommandPalette();
+        palette.register('Save File', 'Ctrl+S', () => {});
+        palette.open();
+        const shortcut = document.querySelector('.command-shortcut');
+        expect(shortcut).not.toBeNull();
+        expect(shortcut.textContent).toBe('Ctrl+S');
+    });
+
+    test('does not display shortcut when empty', () => {
+        const palette = new CommandPalette();
+        palette.register('Test Command', '', () => {});
+        palette.open();
+        const shortcut = document.querySelector('.command-shortcut');
+        expect(shortcut).toBeNull();
+    });
+
+    test('closes on overlay click', () => {
+        const palette = new CommandPalette();
+        palette.open();
+        // Simulate click on the overlay itself
+        const event = new Event('click', { bubbles: true });
+        Object.defineProperty(event, 'target', { value: palette.overlay });
+        palette.overlay.dispatchEvent(event);
+        expect(palette.isOpen()).toBe(false);
+    });
+
+    test('executeSelected does nothing when no commands', () => {
+        const palette = new CommandPalette();
+        palette.open();
+        // Should not throw
+        expect(() => palette.executeSelected()).not.toThrow();
+    });
+
+    test('closes after executing command', () => {
+        const palette = new CommandPalette();
+        palette.register('Test', '', jest.fn());
+        palette.open();
+        palette.executeSelected();
+        expect(palette.isOpen()).toBe(false);
+    });
+});

tests/main-utils.test.js

@@ -0,0 +1,100 @@
+/**
+ * Tests for Main Process Utilities
+ * Tests sanitization, rate limiting, and other main process helpers
+ */
+
+describe('sanitizeErrorMessage', () => {
+    const sanitizeErrorMessage = (message) => {
+        if (typeof message !== 'string') return String(message);
+        return message
+            .replace(/[A-Z]:\\[^\s"']+\\([^\s"'\\]+)/gi, '$1')
+            .replace(/\/[^\s"']+\/([^\s"'/]+)/g, '$1');
+    };
+
+    test('strips Windows absolute paths', () => {
+        expect(sanitizeErrorMessage('Error in C:\\Users\\test\\file.js'))
+            .toBe('Error in file.js');
+    });
+
+    test('strips Unix absolute paths', () => {
+        expect(sanitizeErrorMessage('Error in /home/user/project/file.js'))
+            .toBe('Error in file.js');
+    });
+
+    test('handles non-string input', () => {
+        expect(sanitizeErrorMessage(42)).toBe('42');
+        expect(sanitizeErrorMessage(null)).toBe('null');
+    });
+
+    test('preserves messages without paths', () => {
+        expect(sanitizeErrorMessage('Something went wrong'))
+            .toBe('Something went wrong');
+    });
+
+    test('strips nested Windows paths', () => {
+        expect(sanitizeErrorMessage('Cannot read C:\\Users\\admin\\AppData\\Local\\config.json'))
+            .toBe('Cannot read config.json');
+    });
+
+    test('strips nested Unix paths', () => {
+        expect(sanitizeErrorMessage('File not found: /var/log/app/error.log'))
+            .toBe('File not found: error.log');
+    });
+
+    test('handles undefined input', () => {
+        expect(sanitizeErrorMessage(undefined)).toBe('undefined');
+    });
+});
+
+describe('createRateLimiter', () => {
+    const createRateLimiter = (minIntervalMs = 2000) => {
+        let lastCall = 0;
+        return function canProceed() {
+            const now = Date.now();
+            if (now - lastCall < minIntervalMs) return false;
+            lastCall = now;
+            return true;
+        };
+    };
+
+    test('allows first call', () => {
+        const limiter = createRateLimiter(1000);
+        expect(limiter()).toBe(true);
+    });
+
+    test('blocks rapid calls', () => {
+        const limiter = createRateLimiter(1000);
+        limiter(); // first call
+        expect(limiter()).toBe(false); // too soon
+    });
+
+    test('allows call after interval', () => {
+        jest.useFakeTimers();
+        const limiter = createRateLimiter(1000);
+        limiter();
+        jest.advanceTimersByTime(1001);
+        expect(limiter()).toBe(true);
+        jest.useRealTimers();
+    });
+
+    test('uses default interval of 2000ms', () => {
+        jest.useFakeTimers();
+        const limiter = createRateLimiter();
+        limiter();
+        jest.advanceTimersByTime(1999);
+        expect(limiter()).toBe(false);
+        jest.advanceTimersByTime(2);
+        expect(limiter()).toBe(true);
+        jest.useRealTimers();
+    });
+
+    test('resets after successful call', () => {
+        jest.useFakeTimers();
+        const limiter = createRateLimiter(500);
+        limiter();
+        jest.advanceTimersByTime(501);
+        limiter(); // resets the timer
+        expect(limiter()).toBe(false); // too soon after second call
+        jest.useRealTimers();
+    });
+});

tests/markdown-extensions.test.js

@@ -0,0 +1,130 @@
+/**
+ * Tests for Markdown Extensions
+ * Tests TOC generation, admonition parsing, and PlantUML encoding
+ */
+
+describe('Markdown Extensions', () => {
+    describe('TOC generation from headings', () => {
+        test('extracts all heading levels', () => {
+            const html = '<h1>Title</h1><h2>Section 1</h2><h2>Section 2</h2><h3>Subsection</h3>';
+            const headingRegex = /<h([1-6])[^>]*>(.*?)<\/h[1-6]>/gi;
+            const toc = [];
+            let match;
+            while ((match = headingRegex.exec(html)) !== null) {
+                toc.push({ level: parseInt(match[1]), text: match[2] });
+            }
+            expect(toc).toHaveLength(4);
+            expect(toc[0]).toEqual({ level: 1, text: 'Title' });
+            expect(toc[3]).toEqual({ level: 3, text: 'Subsection' });
+        });
+
+        test('handles empty HTML', () => {
+            const html = '<p>No headings here</p>';
+            const headingRegex = /<h([1-6])[^>]*>(.*?)<\/h[1-6]>/gi;
+            const toc = [];
+            let match;
+            while ((match = headingRegex.exec(html)) !== null) {
+                toc.push({ level: parseInt(match[1]), text: match[2] });
+            }
+            expect(toc).toHaveLength(0);
+        });
+
+        test('handles headings with attributes', () => {
+            const html = '<h1 id="title" class="main">Title</h1><h2 id="sec">Section</h2>';
+            const headingRegex = /<h([1-6])[^>]*>(.*?)<\/h[1-6]>/gi;
+            const toc = [];
+            let match;
+            while ((match = headingRegex.exec(html)) !== null) {
+                toc.push({ level: parseInt(match[1]), text: match[2] });
+            }
+            expect(toc).toHaveLength(2);
+            expect(toc[0].text).toBe('Title');
+        });
+    });
+
+    describe('Admonition regex matching', () => {
+        test('matches note admonition', () => {
+            const src = ':::note\nThis is a note.\n:::\n';
+            const match = src.match(/^:::(note|warning|tip|danger|info)\s*\n([\s\S]*?)^:::\s*$/m);
+            expect(match).not.toBeNull();
+            expect(match[1]).toBe('note');
+            expect(match[2].trim()).toBe('This is a note.');
+        });
+
+        test('matches all admonition types', () => {
+            const types = ['note', 'warning', 'tip', 'danger', 'info'];
+            types.forEach(type => {
+                const src = `:::${type}\nContent\n:::\n`;
+                const match = src.match(/^:::(note|warning|tip|danger|info)\s*\n([\s\S]*?)^:::\s*$/m);
+                expect(match).not.toBeNull();
+                expect(match[1]).toBe(type);
+            });
+        });
+
+        test('does not match invalid admonition type', () => {
+            const src = ':::custom\nContent\n:::\n';
+            const match = src.match(/^:::(note|warning|tip|danger|info)\s*\n([\s\S]*?)^:::\s*$/m);
+            expect(match).toBeNull();
+        });
+
+        test('captures multiline content', () => {
+            const src = ':::warning\nLine 1\nLine 2\nLine 3\n:::\n';
+            const match = src.match(/^:::(note|warning|tip|danger|info)\s*\n([\s\S]*?)^:::\s*$/m);
+            expect(match).not.toBeNull();
+            expect(match[2]).toContain('Line 1');
+            expect(match[2]).toContain('Line 3');
+        });
+    });
+
+    describe('PlantUML hex encoding', () => {
+        const plantumlEncode = (text) => {
+            const hex = Array.from(Buffer.from(text, 'utf-8'))
+                .map(b => b.toString(16).padStart(2, '0'))
+                .join('');
+            return '~h' + hex;
+        };
+
+        test('encodes simple text', () => {
+            const encoded = plantumlEncode('A -> B');
+            expect(encoded).toBe('~h41202d3e2042');
+        });
+
+        test('encodes empty string', () => {
+            expect(plantumlEncode('')).toBe('~h');
+        });
+
+        test('encodes special characters', () => {
+            const encoded = plantumlEncode('@startuml');
+            expect(encoded).toMatch(/^~h[0-9a-f]+$/);
+            // '@' is 0x40, 's' is 0x73
+            expect(encoded.startsWith('~h40')).toBe(true);
+        });
+    });
+
+    describe('Slug generation for TOC anchors', () => {
+        const slugify = (text) => {
+            return text
+                .toLowerCase()
+                .replace(/[^\w\s-]/g, '')
+                .replace(/\s+/g, '-')
+                .replace(/-+/g, '-')
+                .trim();
+        };
+
+        test('converts heading to slug', () => {
+            expect(slugify('Hello World')).toBe('hello-world');
+        });
+
+        test('removes special characters', () => {
+            expect(slugify('What is C++?')).toBe('what-is-c');
+        });
+
+        test('collapses multiple dashes', () => {
+            expect(slugify('Hello   World')).toBe('hello-world');
+        });
+
+        test('handles already lowercase text', () => {
+            expect(slugify('simple')).toBe('simple');
+        });
+    });
+});

tests/preload.test.js

@@ -14,12 +14,29 @@ describe('Preload Security', () => {
       'renderer-ready',
       'get-theme',
       'do-print',
+      'do-print-with-options',
       'export-with-options',
       'export-spreadsheet',
       'batch-convert',
       'select-folder',
       'universal-convert',
       'universal-convert-batch',
+      'image-convert',
+      'image-batch-convert',
+      'image-resize',
+      'image-compress',
+      'image-rotate',
+      'audio-convert',
+      'audio-batch-convert',
+      'audio-extract',
+      'audio-trim',
+      'audio-merge',
+      'video-convert',
+      'video-batch-convert',
+      'video-compress',
+      'video-trim',
+      'video-frames',
+      'video-gif',
       'get-header-footer-settings',
       'save-header-footer-settings',
       'browse-header-footer-logo',
@@ -30,7 +47,26 @@ describe('Preload Security', () => {
       'set-custom-start-page',
       'process-pdf-operation',
       'get-pdf-page-count',
-      'select-pdf-folder'
+      'select-pdf-folder',
+      'open-ascii-generator',
+      'open-table-generator',
+      'insert-generated-content',
+      'save-pasted-image',
+      'load-template',
+      'list-directory',
+      'open-file-path',
+      'git-status',
+      'git-stage',
+      'git-commit',
+      'git-log',
+      'git-diff',
+      'get-snippets',
+      'save-snippet',
+      'delete-snippet',
+      'execute-code',
+      'show-pdf-editor-from-toolbar',
+      'menu-open',
+      'export'
     ];
 
     const EXPECTED_RECEIVE_CHANNELS = [
@@ -54,18 +90,36 @@ describe('Preload Security', () => {
       'show-universal-converter-dialog',
       'show-table-generator',
       'show-pdf-editor-dialog',
+      'show-image-converter',
+      'show-audio-converter',
+      'show-video-converter',
+      'open-pdf-viewer',
       'conversion-status',
       'conversion-complete',
       'batch-progress',
+      'image-conversion-complete',
+      'audio-conversion-complete',
+      'video-conversion-complete',
       'folder-selected',
       'pdf-folder-selected',
       'header-footer-settings-data',
       'header-footer-logo-selected',
       'header-footer-logo-saved',
+      'header-footer-logo-cleared',
       'page-settings-data',
       'pdf-page-count',
       'pdf-operation-complete',
-      'pdf-operation-error'
+      'pdf-operation-error',
+      'pdf-operation-progress',
+      'show-ascii-generator-window',
+      'show-ascii-generator',
+      'show-table-generator-window',
+      'open-header-footer-dialog',
+      'insert-content',
+      'load-template-menu',
+      'toggle-command-palette',
+      'toggle-sidebar-panel',
+      'toggle-bottom-panel'
     ];
 
     test('should define all expected send channels', () => {

tests/print-preview.test.js

@@ -0,0 +1,109 @@
+/**
+ * @jest-environment jsdom
+ */
+
+/**
+ * Tests for PrintPreview
+ * Tests print dialog options, open/close, and preview rendering
+ */
+
+describe('PrintPreview', () => {
+    beforeEach(() => {
+        // Mock electron require for executePrint
+        jest.mock('electron', () => ({
+            ipcRenderer: { send: jest.fn(), invoke: jest.fn() }
+        }), { virtual: true });
+
+        document.body.innerHTML = `
+            <div class="dialog-overlay hidden" id="print-preview-overlay">
+                <button id="print-preview-close"></button>
+                <button id="print-cancel"></button>
+                <button id="print-execute"></button>
+                <select id="print-paper-size"><option value="A4">A4</option><option value="Letter">Letter</option></select>
+                <select id="print-orientation"><option value="portrait">Portrait</option><option value="landscape">Landscape</option></select>
+                <select id="print-margins"><option value="default">Default</option></select>
+                <input type="range" id="print-scale" value="100">
+                <span id="print-scale-value">100%</span>
+                <input type="checkbox" id="print-headers" checked>
+                <input type="checkbox" id="print-background" checked>
+                <select id="print-pages"><option value="all">All</option><option value="custom">Custom</option></select>
+                <input type="text" id="print-page-range" class="hidden">
+                <iframe id="print-preview-frame"></iframe>
+            </div>
+        `;
+    });
+
+    test('getOptions returns default values', () => {
+        const { PrintPreview } = require('../src/print-preview');
+        const preview = new PrintPreview();
+        const options = preview.getOptions();
+        expect(options.paperSize).toBe('A4');
+        expect(options.orientation).toBe('portrait');
+        expect(options.scale).toBe(100);
+        expect(options.headers).toBe(true);
+        expect(options.background).toBe(true);
+        expect(options.pages).toBe('all');
+        expect(options.margins).toBe('default');
+        expect(options.pageRange).toBe('');
+    });
+
+    test('opens and closes', () => {
+        const { PrintPreview } = require('../src/print-preview');
+        const preview = new PrintPreview();
+        preview.open('<p>Test</p>');
+        expect(document.getElementById('print-preview-overlay').classList.contains('hidden')).toBe(false);
+        preview.close();
+        expect(document.getElementById('print-preview-overlay').classList.contains('hidden')).toBe(true);
+    });
+
+    test('updateScaleLabel reflects slider value', () => {
+        const { PrintPreview } = require('../src/print-preview');
+        const preview = new PrintPreview();
+        document.getElementById('print-scale').value = '75';
+        preview.updateScaleLabel();
+        expect(document.getElementById('print-scale-value').textContent).toBe('75%');
+    });
+
+    test('close button closes preview', () => {
+        const { PrintPreview } = require('../src/print-preview');
+        const preview = new PrintPreview();
+        preview.open('<p>Test</p>');
+        document.getElementById('print-preview-close').click();
+        expect(document.getElementById('print-preview-overlay').classList.contains('hidden')).toBe(true);
+    });
+
+    test('cancel button closes preview', () => {
+        const { PrintPreview } = require('../src/print-preview');
+        const preview = new PrintPreview();
+        preview.open('<p>Test</p>');
+        document.getElementById('print-cancel').click();
+        expect(document.getElementById('print-preview-overlay').classList.contains('hidden')).toBe(true);
+    });
+
+    test('getOptions reflects changed values', () => {
+        const { PrintPreview } = require('../src/print-preview');
+        const preview = new PrintPreview();
+
+        // Change paper size to Letter
+        const paperSelect = document.getElementById('print-paper-size');
+        paperSelect.value = 'Letter';
+
+        // Change scale
+        document.getElementById('print-scale').value = '50';
+
+        // Uncheck headers
+        document.getElementById('print-headers').checked = false;
+
+        const options = preview.getOptions();
+        expect(options.paperSize).toBe('Letter');
+        expect(options.scale).toBe(50);
+        expect(options.headers).toBe(false);
+    });
+
+    test('stores last content for refresh', () => {
+        const { PrintPreview } = require('../src/print-preview');
+        const preview = new PrintPreview();
+        preview.open('<p>Hello World</p>');
+        expect(preview._lastContent).toBe('<p>Hello World</p>');
+    });
+});

tests/setup.js

@@ -59,7 +59,7 @@ global.window.electronAPI = {
 // Mock marked library
 global.window.marked = {
   parse: jest.fn((text) => `<p>${text}</p>`),
-  setOptions: jest.fn()
+  use: jest.fn()
 };
 
 // Mock DOMPurify

tests/sidebar.test.js

@@ -0,0 +1,121 @@
+/**
+ * @jest-environment jsdom
+ */
+
+/**
+ * Tests for SidebarManager
+ * Tests panel registration, toggling, expand/collapse behavior
+ */
+
+describe('SidebarManager', () => {
+    let SidebarManager;
+
+    beforeEach(() => {
+        document.body.innerHTML = `
+            <div class="sidebar collapsed" id="sidebar">
+                <div class="sidebar-icons">
+                    <button class="sidebar-icon" data-panel="test1"></button>
+                    <button class="sidebar-icon" data-panel="test2"></button>
+                </div>
+                <div class="sidebar-panel" id="sidebar-panel">
+                    <div class="sidebar-panel-header">
+                        <span class="sidebar-panel-title"></span>
+                        <button class="sidebar-panel-close"></button>
+                    </div>
+                    <div class="sidebar-panel-content" id="sidebar-panel-content"></div>
+                </div>
+            </div>
+        `;
+        SidebarManager = require('../src/sidebar/sidebar-manager').SidebarManager;
+    });
+
+    test('starts collapsed', () => {
+        const mgr = new SidebarManager();
+        expect(document.getElementById('sidebar').classList.contains('collapsed')).toBe(true);
+    });
+
+    test('expands on panel toggle', () => {
+        const mgr = new SidebarManager();
+        mgr.registerPanel('test1', { title: 'Test 1', render: (c) => { c.innerHTML = 'hello'; } });
+        mgr.togglePanel('test1');
+        expect(document.getElementById('sidebar').classList.contains('collapsed')).toBe(false);
+        expect(document.querySelector('.sidebar-panel-title').textContent).toBe('Test 1');
+    });
+
+    test('collapses on second toggle', () => {
+        const mgr = new SidebarManager();
+        mgr.registerPanel('test1', { title: 'Test 1', render: () => {} });
+        mgr.togglePanel('test1');
+        mgr.togglePanel('test1');
+        expect(document.getElementById('sidebar').classList.contains('collapsed')).toBe(true);
+    });
+
+    test('switches panels', () => {
+        const mgr = new SidebarManager();
+        mgr.registerPanel('test1', { title: 'Panel 1', render: (c) => { c.innerHTML = 'one'; } });
+        mgr.registerPanel('test2', { title: 'Panel 2', render: (c) => { c.innerHTML = 'two'; } });
+        mgr.togglePanel('test1');
+        mgr.togglePanel('test2');
+        expect(document.querySelector('.sidebar-panel-title').textContent).toBe('Panel 2');
+        expect(document.getElementById('sidebar-panel-content').innerHTML).toBe('two');
+    });
+
+    test('collapse resets active panel', () => {
+        const mgr = new SidebarManager();
+        mgr.registerPanel('test1', { title: 'Test', render: () => {} });
+        mgr.expand('test1');
+        mgr.collapse();
+        expect(mgr.activePanel).toBe(null);
+    });
+
+    test('expand sets active icon', () => {
+        const mgr = new SidebarManager();
+        mgr.registerPanel('test1', { title: 'Test 1', render: () => {} });
+        mgr.expand('test1');
+        const btn = document.querySelector('[data-panel="test1"]');
+        expect(btn.classList.contains('active')).toBe(true);
+    });
+
+    test('collapse removes active icon', () => {
+        const mgr = new SidebarManager();
+        mgr.registerPanel('test1', { title: 'Test 1', render: () => {} });
+        mgr.expand('test1');
+        mgr.collapse();
+        const btn = document.querySelector('[data-panel="test1"]');
+        expect(btn.classList.contains('active')).toBe(false);
+    });
+
+    test('expand with unregistered panel does nothing', () => {
+        const mgr = new SidebarManager();
+        mgr.expand('nonexistent');
+        expect(document.getElementById('sidebar').classList.contains('collapsed')).toBe(true);
+        expect(mgr.activePanel).toBe(null);
+    });
+
+    test('render function receives panel content element', () => {
+        const mgr = new SidebarManager();
+        const renderFn = jest.fn();
+        mgr.registerPanel('test1', { title: 'Test 1', render: renderFn });
+        mgr.expand('test1');
+        expect(renderFn).toHaveBeenCalledWith(document.getElementById('sidebar-panel-content'));
+    });
+
+    test('clicking sidebar icon toggles panel', () => {
+        const mgr = new SidebarManager();
+        mgr.registerPanel('test1', { title: 'Test 1', render: () => {} });
+        const btn = document.querySelector('[data-panel="test1"]');
+        btn.click();
+        expect(mgr.activePanel).toBe('test1');
+        btn.click();
+        expect(mgr.activePanel).toBe(null);
+    });
+
+    test('clicking close button collapses sidebar', () => {
+        const mgr = new SidebarManager();
+        mgr.registerPanel('test1', { title: 'Test 1', render: () => {} });
+        mgr.expand('test1');
+        document.querySelector('.sidebar-panel-close').click();
+        expect(mgr.activePanel).toBe(null);
+        expect(document.getElementById('sidebar').classList.contains('collapsed')).toBe(true);
+    });
+});