* On macOS and iPhone, added offline Mermaid diagram rendering in Markdown preview with size controls and colors that follow the selected theme. * On macOS, expanded Finder Quick Look to render Mermaid diagrams, syntax-highlighted code blocks, local Markdown images after folder access, and separate code themes for light and dark appearance. * Added separate light and dark code-theme choices across Apple previews, so code remains readable when the system appearance changes. * Opened ordinary links from rendered previews in the default browser while keeping local document anchors inside Writer.

* Fixed a crash that could occur when undoing Markdown edits by rebuilding the undo architecture around native text-edit operations for more reliable undo and redo. * Synced editor accent colors with the selected Markdown theme, including live updates when switching themes. * Improved emphasis rendering and delimiter detection for a more accurate Markdown writing experience. * Preserved find and replace text when switching between editing and preview modes on macOS. * Avoided unnecessary folder permission prompts when saving plain Markdown files without local media references. * Improved PNG export reliability when Markdown images are missing or unavailable. * Fixed the edited state after the first save of a new document. * Made double-clicking the macOS title bar expand the window to the full available screen height while preserving its original size for quick restore.

* Added Markdown-to-PNG export on macOS and iOS.