Mermaid stack-layout patch

Fix Mermaid subgraph direction and add local snapshots so documentation diagrams stay sane

Problem

Heavy Mermaid users hit a long-standing limit: if any node inside a subgraph connects outside, the subgraph ignores the overall direction and the layout becomes unreadable. The official live editor also keeps no history, so a refresh loses work. One developer had to add new syntax and local-storage snapshots themselves.

Solution

An enhanced Mermaid renderer and local editor that supports stack layout and corrected subgraph direction, improves cross-layer edge routing, and auto-saves every edit to browser local storage as browsable snapshots; export to standard Mermaid or SVG for docs.

Users

Developers and teams writing technical docs, architecture diagrams, and READMEs in Mermaid

MVP

Renderer compatible with official syntax; stack-layout extension syntax; subgraph direction fix; local snapshot history with diff; one-click export to image and standard source

Revenue

Free web editor; one-time desktop license or self-hosted team license; subscription for cloud snapshot sync

Why now

Mermaid is the de facto docs standard yet these layout limits remain unfixed, and community demand for a patch is proven