What's new in Mermaid Studio 2026.4.3?

Mermaid Studio 2026.4.3 is a bug-fix release. It fixes a live preview that could temporarily stall on a stale frame after undo and redo, and makes color gutter icons work with every color format in style, classDef, and linkStyle statements.

For the latest features, including Mermaid.js 12 support and the new use case and agentflow diagrams, see what’s new in 2026.4.2.

Changelog

Fixed

• Appearance: applying a theme from the Appearance popup or the Quick Switch Theme action no longer reports an IDE error on 2026.3
• Preview: the live preview no longer occasionally gets stuck on a stale render, especially after undo and redo in the editor
• Preview and Markdown preview: long render errors scroll inside a height-limited banner instead of covering the diagram or document
• Completion: diagram-type completion offers every supported diagram type, including TreeView and Treemap
• Themes: custom and bundled themes now color Agentflow node and container borders
• Color gutter icons: picking a color after a theme change or an edit above the line now updates the right color
• Color gutter icons: style, classDef, and linkStyle values show icons for named, rgb(), and hsl() colors, and a picked color is written as hex
• Block diagram: rgb() and hsl() values in style and classDef statements no longer show syntax errors