Looks interesting! I’m discouraged from using mermaid and D2’s online playground for privacy reasons and have hand on my roadmap to get a local editor. This might be it! Does it support theming of mermaid diagrams, I noted the style keywords were in the roadmap still.

Great catch! Mermaid styling syntax (style and classDef directives) is on the roadmap for v0.3.0. Currently the diagrams render with Ferrite's theme colors (light/dark).

For privacy, you're in the right place — Ferrite's Mermaid rendering is 100% native Rust, no JavaScript, no external services, no network calls. All ~6000 lines of diagram rendering happen locally. We're even planning to extract this as a standalone crate so others can use it.