| name | diagram-code |
| description | 用于生成或维护 Mermaid、D2、PlantUML 等 code-as-graph 架构图、流程图、时序图、状态图和数据流图；匹配画图、架构图、流程图、sequence、state、graph as code；强调可编辑、可追溯。 |
Diagram Code
Create or update reviewable graph source code. This skill exists for repository
artifacts where format choice, traceability, and parser validation matter.
Core Contract
- Produce Mermaid, D2, PlantUML, DOT, or the repository's existing graph format;
do not substitute a raster image unless the user asks for one.
- Reuse the repository's existing diagram language and style when present.
- Map non-obvious nodes and edges to source files, config, documentation,
runtime output, or user-provided facts.
- Keep each diagram focused on one operational question and split crowded views.
Diagram Type Gate
Choose the diagram from the question it must answer:
| Question | Diagram | Default format |
|---|
| Who uses the system and why? | Use case or context | PlantUML usecase / Mermaid |
| What parts exist and where are the boundaries? | Architecture / C4 | D2 |
| What steps happen in order? | Workflow / flowchart | Mermaid flowchart |
| Who calls whom during one request? | Sequence | Mermaid or PlantUML sequence |
| What states can an object enter? | State / lifecycle | Mermaid or PlantUML state |
| Where does data move and transform? | Data flow / lineage | D2 |
| What runs where? | Deployment / infrastructure | D2 |
Prefer Mermaid for Markdown workflows and sequences, D2 for architecture and
deployment boundaries, and PlantUML when the repository already uses it.
Workflow
- Read the relevant source paths, existing diagrams, runtime evidence, or
user-provided description.
- Select the smallest view and graph language that answer the question.
- Use stable semantic node IDs, short labels, meaningful containers, and edge
labels only where protocol, data, event, or condition matters.
- Put source paths or runtime commands in comments or adjacent traceability
notes. Mark assumptions instead of drawing them as confirmed facts.
- Run the smallest available parser or renderer check, such as
d2 fmt,
d2 --check, mmdc, plantuml -checkonly, or the repository check command.
If none is available, report that syntax was reviewed without rendering.
Maintenance Rules
- Patch existing graphs unless their abstraction is wrong.
- Avoid random IDs, timestamps, unnecessary styling, and layout churn.
- Revise crossing-heavy, ambiguous, or overly dense diagrams before delivery.
