diagram

name	diagram
description	Generates Mermaid, Excalidraw JSON, or DBML diagrams. Use when the user asks to "diagram X", "draw the architecture", "generate an ER diagram", "create a sequence diagram", or invokes /sdd:diagram. Accepts a free-text description with `--format` and `--save` flags.
argument-hint	<description> [--format=mermaid|excalidraw|dbml] [--save=./path.ext]
allowed-tools	Read, Write, Grep

diagram

Convert a description into a syntactically valid diagram. Broken syntax is worse than no diagram.

Process

1. Parse args. Flags: --format=mermaid|excalidraw|dbml, --save=<path>. Default mermaid. Infer from description when possible: ER / schema → DBML, whiteboard → Excalidraw, else Mermaid.
2. Pick the diagram type (Mermaid only): flowchart (graph TD), sequence, ER, state, class, C4.
3. Load the format reference and one example before writing:
   • Mermaid → references/mermaid-cheatsheet.md + examples/mermaid-c4.md
   • Excalidraw → references/excalidraw-json-schema.md + examples/excalidraw-microservices.json
   • DBML → references/dbml-syntax.md + examples/dbml-ecommerce.dbml
4. Generate with rules:
   • Label every edge (protocol + purpose)
   • Group related components (subgraphs / TableGroups)
   • ≤15 nodes per diagram; split larger designs into layered views
   • Top-to-bottom for request flows, left-to-right for pipelines
   • Dashed for async, solid for sync
   • DBML: include Indexes {} where they matter + Note: per table
5. Validate before returning:
   • Mermaid: unclosed nodes, missing direction, mismatched brackets
   • DBML: every Ref: references existing tables
   • Excalidraw: valid JSON; every binding elementId exists
6. Output in a fenced block with the correct language tag (mermaid / json / ```dbml). Excalidraw: add "File → Open → paste." DBML: add "paste at https://dbdiagram.io."
7. If --save=<path> was given, write the file. Otherwise offer to save.