utility-mermaid-diagrams

Original：🇺🇸 English

Translated

Teaches PMs to create syntactically valid mermaid diagrams by selecting the right diagram type for their communication need, following syntax validity rules, and validating before shipping. Covers all 15 mermaid diagram types with PM-relevant examples and a dual-lens navigation system.

5installs

Sourceproduct-on-purpose/pm-skills

Added on2026-04-29

NPX Install

npx skill4agent add product-on-purpose/pm-skills utility-mermaid-diagrams

SKILL.md Content

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Mermaid Diagrams

Create effective, syntactically valid mermaid diagrams for product documents.

When to Use

Creating mermaid diagrams for PRDs, specs, roadmaps, or stakeholder presentations
Choosing which of 15 diagram types fits a specific communication need
Debugging mermaid code that won't render or renders incorrectly
Reviewing diagrams for clarity, accuracy, and accessibility

When NOT to Use

Exporting diagrams to image files (PNG/SVG) . that's a rendering tool concern
Using non-mermaid diagramming tools (Figma, Lucidchart, draw.io)
Creating purely decorative visuals with no informational purpose

The Cardinal Rule

Don't diagram what a list can say.

Diagrams earn their place when they reveal relationships, branching, or flow that prose flattens. Before creating any diagram, ask:

Does this show branching, relationships, or flow that a list or table would flatten?

Yes → proceed with a diagram
No → use a numbered list, bullet list, or table instead

A 5-step linear process is a list. A 5-step process with two decision points and a retry loop is a diagram.

Diagram Selection Guide

I need to show...	Use	Also consider
A decision or approval process	Flowchart	State
Multi-service or multi-party interactions	Sequence	Flowchart
Feature lifecycle or status transitions	State	Flowchart
Work stages or pipeline status	Kanban	State
Release or sprint timeline with dependencies	Gantt	Timeline
Version history or chronological milestones	Timeline	Gantt
2D prioritization (effort/impact, risk/value)	Quadrant	.
Allocation breakdown or composition	Pie	Treemap
Problem decomposition or brainstorming	Mindmap	.
Domain models or data relationships	ER	Class
API or object contracts	Class	ER
System topology or infrastructure	Architecture	Flowchart
Flow quantities or budget allocation	Sankey	Pie
Hierarchical proportional data	Treemap	Pie
Trends or time-series metrics	XY-Chart	.

For worked examples organized by PM task, see

references/pm-use-cases.md

. For full syntax and options per type, see

references/diagram-catalog.md

Syntax Validity Principles

Six rules that prevent most rendering failures:

Quote labels . Any label containing spaces, parentheses, brackets, colons, commas, or reserved words must be quoted with double quotes
Escape special characters . Characters with mermaid or markdown meaning (
```
>
```
,
```
<
```
,
```
-
```
at line start,
```
#
```
) need escaping or quoting
Declare before referencing . Define a node before using it in an edge; referencing an undeclared node causes silent failures in some types
Respect limits . Each diagram type has a maximum node/participant count beyond which readability collapses (see
```
references/diagram-catalog.md
```
for per-type limits)
Comment your intent . Use
```
%%
```
comments to document non-obvious choices (why this layout direction, why this grouping)
Test before shipping . Paste into a mermaid renderer (mermaid.live, VS Code preview, or your target environment) and verify it renders correctly

For the complete syntax reference, see

references/syntax-guide.md

Instructions

Identify what you're communicating . What relationship, flow, hierarchy, or proportion needs to be visible? Who is the audience?
Apply the cardinal rule . Confirm a diagram adds value over a list or table
Select a diagram type . Use the selection guide above, browse
```
references/pm-use-cases.md
```
by task, or browse
```
references/diagram-catalog.md
```
by type
Plan the diagram . Fill out the planning worksheet in
```
references/TEMPLATE.md
```
: purpose, audience, node inventory, type rationale
Write the mermaid code . Follow
```
references/syntax-guide.md
```
rules; start with the minimal syntax example from
```
references/diagram-catalog.md
```
and expand
Validate . Run through the quality checklist below
Embed . Place the validated mermaid code block in your document

Output Contract

Planning artifact: A completed diagram planning worksheet (
```
references/TEMPLATE.md
```
)
Final output: A syntactically valid mermaid code block embedded in the target document
Quality gate: All items in the quality checklist pass

Quality Checklist

Diagram renders without error in target environment
Cardinal rule satisfied . a list or table would not communicate this more clearly
No linear sequences without branching, relationships, or hierarchy
All labels with spaces or special characters are properly quoted
Special characters escaped where needed
Node/participant count within type-specific limits
Colors are accessible (WCAG AA 3:1 contrast minimum, black text on light backgrounds)
Color is never the sole differentiator . shapes and labels also distinguish elements
Diagram has a descriptive title or surrounding prose context
```
%%
```
comments document any non-obvious layout or grouping choices

References

File	Purpose
`references/TEMPLATE.md`	Diagram planning worksheet . fill out before writing mermaid code
`references/EXAMPLE.md`	Worked example: PM creating 4 diagrams for a product launch
`references/diagram-catalog.md`	All 15 diagram types: syntax, PM examples, limits, pitfalls
`references/pm-use-cases.md`	PM task → diagram type mapping with mini worked examples
`references/syntax-guide.md`	Complete syntax validity rules, escaping, styling, and validation checklist