Add export chat as Markdown feature

Adds a download button to the chat section toolbar and a command palette
entry that exports the current chat conversation as a Markdown file.

The export formats messages with sender names, timestamps, and proper
Markdown structure. The file is downloaded directly to the user's machine.

Changes:
- Add `downloadChatAsMarkdown` and `formatChatAsMarkdown` utilities
- Add export button to `ChatSection` toolbar (download icon)
- Add `exportChat` command to the command palette
- Export `downloadChatAsMarkdown` from `@jupyter/chat` public API

Closes #328

Author: erkin98

packages/jupyter-chat/src/index.ts

@@ -13,4 +13,5 @@ export * from './registers';
 export * from './selection-watcher';
 export * from './tokens';
 export * from './types';
+export * from './utils';
 export * from './widgets';

packages/jupyter-chat/src/utils.ts

@@ -10,7 +10,7 @@ import { FileEditor } from '@jupyterlab/fileeditor';
 import { Notebook } from '@jupyterlab/notebook';
 import { Widget } from '@lumino/widgets';
 
-import { IUser } from './types';
+import { IMessage, IUser } from './types';
 
 const MENTION_CLASS = 'jp-chat-mention';
 
@@ -81,3 +81,56 @@ export function replaceSpanToMention(content: string, user: IUser): string {
   const regex = new RegExp(mentionEl, 'g');
   return content.replace(regex, mention);
 }
+
+/**
+ * Trigger a browser download of a Markdown-formatted chat export.
+ *
+ * @param chatName - Raw model name (e.g. "path/to/my.chat"). Used to derive the
+ *   filename and as the document title passed to formatChatAsMarkdown.
+ * @param messages - Messages to export.
+ */
+export function downloadChatAsMarkdown(
+  chatName: string,
+  messages: ReadonlyArray<IMessage>
+): void {
+  // Use || (not ??) so that empty string '' also falls back to 'chat'.
+  const name = chatName || 'chat';
+  const basename = name.split('/').pop()?.replace(/\.chat$/, '') || name;
+  const markdown = formatChatAsMarkdown(basename, messages);
+  const blob = new Blob([markdown], { type: 'text/markdown' });
+  const url = URL.createObjectURL(blob);
+  const a = document.createElement('a');
+  a.href = url;
+  a.download = `${basename}.md`;
+  a.style.display = 'none';
+  document.body.appendChild(a); // Firefox requires DOM attachment
+  a.click();
+  document.body.removeChild(a);
+  setTimeout(() => URL.revokeObjectURL(url), 100); // delayed to avoid premature revoke
+}
+
+/**
+ * Format chat messages as a Markdown document for export.
+ *
+ * @param chatName - The display name of the chat, used as the document title.
+ * @param messages - Messages to format. Deleted messages are skipped.
+ * @returns A Markdown-formatted string ready for download.
+ */
+export function formatChatAsMarkdown(
+  chatName: string,
+  messages: ReadonlyArray<IMessage>
+): string {
+  const lines: string[] = [`# ${chatName}`, ''];
+  const visibleMessages = messages.filter(msg => !msg.deleted);
+  if (visibleMessages.length === 0) {
+    lines.push('*(No messages)*', '');
+    return lines.join('\n');
+  }
+  for (const msg of visibleMessages) {
+    const displayName = msg.sender.display_name || msg.sender.username || 'Unknown';
+    const timestamp = new Date(msg.time * 1000).toLocaleString();
+    const body = typeof msg.body === 'string' ? msg.body : '[Rich content]';
+    lines.push(`**${displayName}** — ${timestamp}`, '', body, '', '---', '');
+  }
+  return lines.join('\n');
+}

packages/jupyter-chat/src/widgets/multichat-panel.tsx

@@ -13,6 +13,7 @@ import { nullTranslator, TranslationBundle } from '@jupyterlab/translation';
 import {
   addIcon,
   closeIcon,
+  downloadIcon,
   launchIcon,
   PanelWithToolbar,
   ReactWidget,
@@ -36,6 +37,7 @@ import {
 import { TRANSLATION_DOMAIN } from '../context';
 import { chatIcon, readIcon } from '../icons';
 import { IChatModel } from '../model';
+import { downloadChatAsMarkdown } from '../utils';
 
 const SIDEPANEL_CLASS = 'jp-chat-sidepanel';
 const ADD_BUTTON_CLASS = 'jp-chat-add';
@@ -534,6 +536,19 @@ class SidePanelWidget extends PanelWithToolbar {
       this.toolbar.addItem('rename', renameButton);
     }
 
+    const exportButton = new ToolbarButton({
+      icon: downloadIcon,
+      iconLabel: 'Export chat as Markdown',
+      className: 'jp-mod-styled',
+      onClick: () => {
+        try {
+          downloadChatAsMarkdown(this.model.name, this.model.messages);
+        } catch (err) {
+          console.error('Failed to export chat:', err);
+        }
+      }
+    });
+    this.toolbar.addItem('export', exportButton);
     if (options.openInMain) {
       const moveToMain = new ToolbarButton({
         icon: launchIcon,

packages/jupyterlab-chat-extension/src/index.ts

@@ -52,7 +52,7 @@ import { IRenderMimeRegistry } from '@jupyterlab/rendermime';
 import { Contents } from '@jupyterlab/services';
 import { ISettingRegistry } from '@jupyterlab/settingregistry';
 import { ITranslator, nullTranslator } from '@jupyterlab/translation';
-import { launchIcon } from '@jupyterlab/ui-components';
+import { downloadIcon, launchIcon } from '@jupyterlab/ui-components';
 import { PromiseDelegate } from '@lumino/coreutils';
 import {
   ChatWidgetFactory,
@@ -70,6 +70,7 @@ import {
   chatFileType,
   getDisplayName
 } from 'jupyterlab-chat';
+import { downloadChatAsMarkdown } from '@jupyter/chat';
 import { chatCommandRegistryPlugin } from './chat-commands/plugins';
 import { emojiCommandsPlugin } from './chat-commands/providers/emoji';
 import { mentionCommandsPlugin } from './chat-commands/providers/user-mention';
@@ -835,6 +836,23 @@ const chatCommands: JupyterFrontEndPlugin<void> = {
       }
     });
 
+    // Command to export the current chat as a Markdown file.
+    commands.addCommand(CommandIDs.exportChat, {
+      label: 'Export chat as Markdown',
+      icon: downloadIcon,
+      isEnabled: () => tracker.currentWidget !== null,
+      execute: () => {
+        const widget = tracker.currentWidget;
+        if (!widget) {
+          return;
+        }
+        try {
+          downloadChatAsMarkdown(widget.model.name, widget.model.messages);
+        } catch (err) {
+          console.error('Failed to export chat:', err);
+        }
+      }
+    });
     // The command to focus the input of the current chat widget.
     commands.addCommand(CommandIDs.focusInput, {
       caption: trans.__('Focus the input of the current chat widget'),
@@ -866,6 +884,10 @@ const chatCommands: JupyterFrontEndPlugin<void> = {
         category: trans.__('Chat'),
         command: CommandIDs.renameChat
       });
+      commandPalette.addItem({
+        category: 'Chat',
+        command: CommandIDs.exportChat
+      });
     }
 
     // Add the create command to the launcher

packages/jupyterlab-chat/src/token.ts

@@ -108,7 +108,11 @@ export const CommandIDs = {
   /**
    * Open a chat and send a message into it.
    */
-  openWithMessage: 'jupyterlab-chat:openWithMessage'
+  openWithMessage: 'jupyterlab-chat:openWithMessage',
+  /**
+   * Export the current chat as a Markdown file.
+   */
+  exportChat: 'jupyterlab-chat:exportChat'
 };
 
 /**