Mermaid Diagram Syntax

Complete syntax reference for all Mermaid diagram types. Enables AI agents to construct valid diagrams with correct syntax, structure, and configuration across flowcharts, sequence diagrams, class diagrams, state diagrams, ER diagrams, gantt charts, git graphs, mindmaps, timelines, user journeys, data charts, and advanced diagram types.

Scope

TRIGGER: Activate when the user asks to create, fix, or modify any Mermaid diagram, or when generating Mermaid diagram code of any type.

COVERS:

• Flowchart/graph diagrams — node shapes, edge types, subgraphs, styling, interactivity
• Sequence diagrams — actors, messages, loops, activations, notes
• Class diagrams — classes, relationships, methods, visibility
• State diagrams — states, transitions, composite states, forks
• Entity-relationship diagrams — entities, attributes, relationships
• Gantt charts — tasks, sections, dependencies, date formats
• Git graphs — commits, branches, merges, cherry-picks
• Mindmaps — nodes, icons, classes, shapes
• Timeline and user journey diagrams