d2lang

name: d2lang description: Generate, refactor, debug, and explain D2 diagrams using documented D2 language and CLI behavior. Use when requests mention D2, .d2 files, architecture/flow/ERD/sequence/class diagrams, imports, layers/scenarios/steps composition, D2 layout/style tuning, or D2 render/format/validate/export commands.

D2lang

Goal

Produce valid, readable .d2 that renders correctly with documented D2 syntax/CLI.

Intake Gate

Before writing a new diagram, confirm:

• Diagram type.
• Required entities and relationships.
• Required grouping/containers.
• Output/format/layout constraints (if any).

Clarifying protocol:

1. Ask at most 3 high-impact questions.
2. Prioritize structure, then relationships, then constraints.
3. Proceed with explicit assumptions only for non-safety-critical ambiguity.
4. If ambiguity can impact security, auth, data integrity, compliance, or destructive operations, stop and ask for clarification.

Workflow

1. Classify diagram and minimum nodes/edges.
2. Choose layout strategy (elk for dense graphs, dagre for simple flows unless user specifies otherwise).
3. Define containers/shapes first, then connections.
4. Apply shared styles (classes/globs) before local overrides.
5. Use imports/composition only when requested or clearly beneficial.
6. Validate and format before finalizing.

D2 Rules (Strict)

• Use documented operators only: --, ->, <-, <->.
• Connect by key, not label.
• Quote reserved/special keys when needed.
• Keep paths unambiguous for nested containers.
• Use null intentionally for deletions.

CLI

d2 fmt diagram.d2
d2 validate diagram.d2
d2 diagram.d2 diagram.svg

Optional exports: pdf, pptx, gif, txt when requested.

Response Contract

Always:

1. Return one complete .d2 file in a fenced d2 block (unless user asks partial).
2. Include Assumptions when details are missing.
3. Include one short layout rationale.
4. Include one recommended render command (and optional validate command).
5. Preserve semantics first when refactoring existing diagrams.

Compatibility

• If co-triggered with review-oriented skills, treat review feedback as internal constraints.
• Final user-facing output remains this skill’s .d2 response contract unless user requests a separate review artifact.