graphviz

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Graphviz DOT Diagram Generator

Important: Use dot as the code fence identifier, NOT graphviz .

Quick Start: Choose digraph (directed) or graph (undirected) → Define nodes with attributes (shape, color, label) → Connect with -> or -- → Set layout (rankdir, spacing) → Wrap in dot fence. Default: top-to-bottom (rankdir=TB), cluster names must start with cluster_, use semicolons.

Critical Syntax Rules

Rule 1: Cluster Naming

❌ subgraph backend { }      → Won't render as box
✅ subgraph cluster_backend { }  → Must start with cluster_

Rule 2: Node IDs with Spaces

❌ API Gateway [label="API"];    → Invalid ID
✅ "API Gateway" [label="API"];  → Quote the ID
✅ api_gateway [label="API Gateway"];  → Use underscore ID

Rule 3: Edge Syntax Difference

digraph: A -> B;   → Directed arrow
graph:   A -- B;   → Undirected line

Rule 4: Attribute Syntax

❌ node [shape=box color=red]    → Missing comma
✅ node [shape=box, color=red];  → Comma separated

Rule 5: HTML Labels

✅ shape=plaintext for HTML labels
✅ Use < > not " " for HTML content

Common Pitfalls

Issue	Solution
Nodes overlapping	Increase `nodesep` and `ranksep`
Poor layout	Change `rankdir` or add `{rank=same}`
Edges crossing	Use `splines=ortho` or adjust node order
Cluster not showing	Name must start with `cluster_`
Label not displaying	Check quote escaping

Output Format

`markdown

digraph G { [diagram code] }

Related Files

For advanced layout control and complex styling, refer to references below:

syntax.md — Layout control (rankdir, splines, rank), HTML labels, edge styles, cluster subgraphs, and record-based nodes