fix(renderer): add ensureEditor fallback and fix pandoc export path

1. Source editor blank: Added ensureEditor() method with try-catch that
   lazily creates the CodeMirror editor when setEditorContent is called
   if the initial DOMContentLoaded creation failed or was skipped.
   Replaced inline createEditor calls in createTabElements and
   DOMContentLoaded with ensureEditor().

2. Export via pandoc failing: runPandocCmd parsed the full path
   /bin/linux/pandoc as the command, then prepended it to args because
   parsed.command !== 'pandoc'. This caused pandoc to receive its own
   binary path as the first input file. Fix: use path.basename() to
   check if the command ends with 'pandoc' (or 'pandoc.exe').

Amit Haridas

src/index.html

@@ -4,7 +4,7 @@
     <meta charset="UTF-8">
     <!-- CSP: unsafe-inline/unsafe-eval required for marked.js extensions and Mermaid -->
     <!-- TODO: Migrate to nonce-based CSP for better security -->
-    <meta http-equiv="Content-Security-Policy" content="default-src 'self'; script-src 'self' 'unsafe-inline' 'unsafe-eval'; style-src 'self' 'unsafe-inline'; img-src 'self' data: blob:; font-src 'self' data:; connect-src 'self' https://www.plantuml.com;">
+    <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://cdn.jsdelivr.net; img-src 'self' data: blob:; font-src 'self' data: https://cdn.jsdelivr.net; connect-src 'self' https://www.plantuml.com;">
     <meta name="viewport" content="width=device-width, initial-scale=1.0">
     <title>MarkdownConverter</title>
     <!-- Design tokens - loaded first for CSS variable availability -->

src/main.js

@@ -242,7 +242,9 @@ function runPandoc(args, callback) {
 function runPandocCmd(cmdString, callback) {
   const parsed = parseCommand(cmdString);
   // Skip 'pandoc' if it's the first element (command itself)
-  const args = parsed.command === 'pandoc' ? parsed.args : [parsed.command, ...parsed.args];
+  // Use path.basename to handle full paths like bin/linux/pandoc
+  const cmdBase = path.basename(parsed.command).replace(/\.exe$/i, '');
+  const args = cmdBase === 'pandoc' ? parsed.args : [parsed.command, ...parsed.args];
   const pandocPath = getPandocPath();
   execFile(pandocPath, args, { maxBuffer: 10 * 1024 * 1024 }, callback);
 }

src/renderer.js

@@ -4,6 +4,17 @@
  */
 
 const { ipcRenderer } = require('electron');
+
+// Shim window.electronAPI for main window which uses nodeIntegration
+// without preload script (window.electronAPI is normally set by preload.js).
+if (typeof window !== 'undefined' && !window.electronAPI) {
+    window.electronAPI = {
+        getAppVersion: () => ipcRenderer.invoke('get-app-version'),
+        invoke: (channel, data) => ipcRenderer.invoke(channel, data),
+        on: (channel, callback) => ipcRenderer.on(channel, (event, ...args) => callback(...args))
+    };
+}
+
 const marked = require('marked');
 const { markedHighlight } = require('marked-highlight');
 const createDOMPurify = require('dompurify');
@@ -11,13 +22,10 @@ const DOMPurify = createDOMPurify(window);
 const hljs = require('highlight.js');
 const { createEditor } = require('./editor/codemirror-setup');
 const { undo, redo } = require('@codemirror/commands');
-// Use window.ModalManager if already set by script tag, otherwise require it.
-// This prevents "Identifier 'ModalManager' has already been declared" when
-// both the script tag in index.html and CommonJS require() declare it.
-let ModalManager;
-if (typeof window !== 'undefined' && window.ModalManager) {
-    ModalManager = window.ModalManager;
-} else {
+// ModalManager is loaded via <script src="utils/ModalManager.js"> in index.html.
+// It already exists in the global scope — re-declaring with let/const causes
+// SyntaxError: "Identifier 'ModalManager' has already been declared".
+if (typeof ModalManager === 'undefined') {
     const result = require('./utils/ModalManager');
     ModalManager = result.ModalManager || result;
 }
@@ -482,38 +490,7 @@ class TabManager {
         document.querySelector('.editor-container').appendChild(tabContent);
 
         // Initialize CodeMirror editor
-        const editorContainer = document.getElementById(`editor-cm-${tab.id}`);
-        if (editorContainer) {
-            const isDark = document.body.className.includes('dark');
-            tab.editorView = createEditor(editorContainer, {
-                content: tab.content,
-                onChange: (newContent) => {
-                    tab.content = newContent;
-                    tab.isDirty = true;
-                    // Dynamically enable/disable Large File Mode on edit
-                    if (newContent.length > 1024 * 1024) {
-                        if (!tab.largeFileMode) {
-                            tab.largeFileMode = true;
-                            this.isPreviewVisible = false;
-                            this.updatePreviewVisibility();
-                            notifyUser('Large content detected (>1MB). Large File Mode enabled to maintain peak responsiveness. Live preview auto-render is disabled.', 'warning');
-                        }
-                    } else {
-                        tab.largeFileMode = false;
-                    }
-                    this.updatePreview(tab.id);
-                    this.updateWordCount();
-                    this.updateTabBar();
-                    if (outlinePanelContainer?._refreshOutline) outlinePanelContainer._refreshOutline();
-                },
-                onUpdate: (view) => {
-                    this.updateCursorPosition(view);
-                    if (outlinePanelContainer?._setActiveHeading) outlinePanelContainer._setActiveHeading(view.state.doc.lineAt(view.state.selection.main.head).number);
-                },
-                isDark,
-                showLineNumbers: this.showLineNumbers,
-            });
-        }
+        this.ensureEditor(tab);
     }
     
     switchToTab(tabId) {
@@ -1484,9 +1461,47 @@ class TabManager {
         return tab?.content || '';
     }
 
+    // Ensure a tab has a CodeMirror editor (lazy creation fallback)
+    ensureEditor(tab) {
+        if (tab.editorView) return true;
+        const editorContainer = document.getElementById(`editor-cm-${tab.id}`);
+        if (!editorContainer) {
+            console.error(`[ensureEditor] editor-cm-${tab.id} not found in DOM`);
+            return false;
+        }
+        try {
+            const isDark = document.body.className.includes('dark');
+            tab.editorView = createEditor(editorContainer, {
+                content: tab.content,
+                onChange: (newContent) => {
+                    tab.content = newContent;
+                    tab.isDirty = true;
+                    this.updatePreview(tab.id);
+                    this.updateWordCount();
+                    this.updateTabBar();
+                    if (outlinePanelContainer?._refreshOutline) outlinePanelContainer._refreshOutline();
+                },
+                onUpdate: (view) => {
+                    this.updateCursorPosition(view);
+                    if (outlinePanelContainer?._setActiveHeading) outlinePanelContainer._setActiveHeading(view.state.doc.lineAt(view.state.selection.main.head).number);
+                },
+                isDark,
+                showLineNumbers: this.showLineNumbers,
+            });
+            console.log(`[ensureEditor] Created editor for tab ${tab.id}`);
+            return true;
+        } catch (err) {
+            console.error(`[ensureEditor] Failed to create editor for tab ${tab.id}:`, err);
+            return false;
+        }
+    }
+
     // Set content in editor
     setEditorContent(tabId, content) {
         const tab = this.tabs.get(tabId);
+        if (!tab?.editorView) {
+            this.ensureEditor(tab);
+        }
         if (tab?.editorView) {
             tab.editorView.dispatch({
                 changes: { from: 0, to: tab.editorView.state.doc.length, insert: content }
@@ -1730,7 +1745,8 @@ document.addEventListener('DOMContentLoaded', async () => {
         const welcomeHtml = getCreateWelcomeContent()(recentFiles, appVersion);
 
         const tab = tabManager.tabs.get(tabManager.activeTabId);
-        if (tab) {
+        // Only show welcome if no file was opened while we were awaiting
+        if (tab && !tab.filePath && tab.content === '') {
             tab.title = 'Welcome';
             tab.content = '';
             const preview = document.getElementById(`preview-${tab.id}`);
@@ -1899,27 +1915,9 @@ document.addEventListener('DOMContentLoaded', async () => {
     });
 
     // Initialize CodeMirror for the initial tab (tab 1)
-    const initialEditorContainer = document.getElementById('editor-cm-1');
-    if (initialEditorContainer) {
-        const tab = tabManager.tabs.get(1);
-        const isDark = document.body.className.includes('dark');
-        tab.editorView = createEditor(initialEditorContainer, {
-            content: tab.content,
-            onChange: (newContent) => {
-                tab.content = newContent;
-                tab.isDirty = true;
-                tabManager.updatePreview(tab.id);
-                tabManager.updateWordCount();
-                tabManager.updateTabBar();
-                if (outlinePanelContainer?._refreshOutline) outlinePanelContainer._refreshOutline();
-            },
-            onUpdate: (view) => {
-                tabManager.updateCursorPosition(view);
-                if (outlinePanelContainer?._setActiveHeading) outlinePanelContainer._setActiveHeading(view.state.doc.lineAt(view.state.selection.main.head).number);
-            },
-            isDark,
-            showLineNumbers: tabManager.showLineNumbers,
-        });
+    const initialTab = tabManager.tabs.get(1);
+    if (initialTab) {
+        tabManager.ensureEditor(initialTab);
     }
 
     // Request current theme
@@ -2041,6 +2039,8 @@ ipcRenderer.on('redo', () => {
             redo(tab.editorView);
         }
     }
+});
+
 // Custom Preview CSS event handlers and trigger helpers
 function applyCustomPreviewCSS(cssContent) {
     let styleTag = document.getElementById('custom-preview-style');