feat(ui): redesign Explorer, toolbar icons, and localization

[ThisIs-Developer]

Summary

This PR delivers a complete Markdown Viewer interface refresh centered on clearer branding, a professional document Explorer, a better-organized toolbar, consistent icons, responsive behavior, and application-wide localization.

The redesign remains lightweight and preserves the existing editor, preview, import, export, sharing, review, storage, and desktop functionality.

Release

• Prepares application version 3.9.3 across the web runtime, service-worker cache, Neutralino configuration, desktop package metadata, bundled desktop script, and changelog.
• Successfully generated all seven standalone Linux, macOS, and Windows binaries for the release candidate.

Application branding and empty state

• Restores the established application identity layout with the 32px app mark, centered subtitle, and adjacent GitHub action.
• Keeps the existing application-header height and its familiar responsive behavior.
• Adds Open Explorer as the first empty-document Quick Start action.
• Opens the existing responsive document sidebar directly on desktop and mobile.
• Keeps the new action fully localized by reusing labels available in all 14 locale catalogs.

Explorer and document management

• Adds a closable left-hand Explorer beside the document tab bar.
• Supports workspaces, nested folders, files, favorites, recent documents, and secret-workspace access.
• Makes complete workspace and folder rows expandable using pointer, Enter, and Space input while maintaining aria-expanded.
• Adds normal, Ctrl/Command, and Shift multi-selection for files and folders.
• Adds context-sensitive right-click and three-dot menus containing only supported actions.
• Supports safe bulk deletion with confirmation and drag-and-drop movement between folders and workspaces.
• Keeps closing a tab separate from deleting its document.
• Imports GitHub files into a repository-named folder and displays background import progress.

Tabs and split view

• Adds tab commands for Close, Close Others, Close Left, Close Right, and Close All.
• Supports synchronized two-document split view through one combined split tab.
• Keeps both split documents in the same Edit or Preview mode and synchronizes scrolling.
• Uses compact truncation for long single and split-document names.

Toolbar and icon redesign

• Reorganizes formatting controls by workflow and frequency of use.
• Keeps the header focused on New, Export, Share, Live Share, Report, About, and Settings.
• Standardizes dropdown styling, keyboard dismissal, spacing, and interaction behavior.
• Uses a locally bundled Lucide icon subset with consistent 1.5px strokes and no heavy runtime dependency.
• Retains the recognizable Bootstrap GitHub brand mark as the icon-system exception.
• Uses compact segmented Edit, Split, and Preview controls.
• Promotes Diagram & More to the main formatting toolbar and simplifies Insert to a three-dot control.

Responsive interface and overlays

• Replaces the floating mobile menu with a compact full-height workspace drawer.
• Organizes mobile View, Document Tools, Actions, and Settings sections with accordion behavior.
• Keeps mobile toolbar and tab-strip sizing aligned with the desktop interface.
• Improves empty-document behavior and disables document-only actions when no document is open.
• Standardizes modal typography, padding, close controls, focus behavior, and responsive layout.
• Refines GitHub import, Share Snapshot, Live Share, Markdown alerts, symbol, emoji, move, rename, and About dialogs.

Localization

• Adds complete interface catalogs for English, Simplified Chinese, Traditional Chinese, Japanese, Korean, Portuguese, Spanish, French, German, Russian, Italian, Turkish, Polish, and Ukrainian.
• Covers 1,029 interface strings per locale, including dynamic dialogs, context menus, Explorer states, editor placeholders, progress messages, validation feedback, titles, and ARIA labels.
• Localizes dynamically created UI without re-rendering editor content.
• Preserves Markdown source, preview content, filenames, user comments, GitHub tree names, language autonyms, and symbolic controls.
• Loads only the selected locale and retains offline web and desktop support.

Desktop support

• Synchronizes the Neutralino desktop resources with the redesigned web application.
• Includes all locale catalogs in the offline desktop bundle.
• Preserves native file dialogs, storage mirroring, external-file opening, and seven standalone build targets.

User impact

• Product identity is cleaner and easier to scan.
• File and folder organization is easier to discover and operate.
• The empty state now provides a direct path into the Explorer.
• Toolbar actions are more consistent and less crowded.
• Desktop and mobile layouts share the same interaction language.
• Users can operate the complete interface in their selected supported language.

Validation

• Catalog integrity previously verified across 1,029 keys and 14 catalogs, with no missing values, mismatched keys, or broken placeholders.
• Korean and Chinese screenshot-state browser checks previously passed.
• Responsive and Explorer regression suites previously passed.
• Static translation coverage previously found no untranslated catalogued text nodes, placeholders, titles, or ARIA labels.
• Web and seven-target Neutralino desktop builds previously passed.
• The latest header restoration was packaged successfully into all seven Neutralino desktop targets; per request, no test suite was run.

Commit style

Conventional commit messages are used throughout this branch, including feat, fix, style, refactor, and chore.

[vercel]

The latest updates on your projects. Learn more about Vercel for GitHub.

Project	Deployment	Actions	Updated (UTC)
markdown-viwer	Ready	Preview, Comment	Jul 19, 2026 9:39pm

[cloudflare-workers-and-pages]

Deploying markdownviewer with    Cloudflare Pages

Latest commit:	4c04ef7
Status:	✅  Deploy successful!
Preview URL:	https://162263f4.markdownviewer.pages.dev
Branch Preview URL:	https://feature-ui-explorer-toolbar.markdownviewer.pages.dev

View logs