plantuml-syntax

name plantuml-syntax description PlantUML syntax reference, C4-PlantUML first, for writing or fixing a diagram in an artefact: sequence, class, activity, state, ER, component, deployment and use-case diagrams, skinparams and themes, C4 layout conflicts and rendering errors. Not needed for Mermaid (mermaid-syntax), or when the request is for a governed diagram artefact with document control, which /arckit:diagram produces. paths ["**/*.puml","**/*.plantuml","**/ARC-*-DIAG-*.md"] PlantUML Syntax Reference A comprehensive reference for PlantUML diagram types with a focus on C4-PlantUML for architecture diagrams. This skill provides syntax documentation adapted from the SpillwaveSolutions/plantuml project, supplemented with ArcKit-specific C4 layout conflict rules and best practices. This skill ships reference material, not runnable scripts. Read the relevant reference file with Read , apply the syntax, and write the diagram into the user's artefact. Do not Bash -execute anything from references/ — they are PlantUML/C4 syntax docs, not commands. Supported Diagram Types Select the appropriate diagram type and read the corresponding reference file: Type Reference ArcKit Commands Using It C4-PlantUML c4-plantuml.md /arckit:diagram (C4 Context, Container, Component) Sequence Diagram sequence-diagrams.md /arckit:diagram (Sequence mode) Class Diagram class-diagrams.md — Activity Diagram activity-diagrams.md — State Diagram state-diagrams.md — ER Diagram er-diagrams.md — Component Diagram component-diagrams.md — Use Case Diagram use-case-diagrams.md — Deployment Diagram deployment-diagrams.md — Styling & Errors Topic Reference Common Syntax Errors common-syntax-errors.md Styling Guide styling-guide.md C4-PlantUML (Primary Use Case) The C4-PlantUML reference is the most important file for ArcKit users. It covers: Include URLs for C4 libraries Element syntax (Person, System, Container, Component, and their variants) Boundary syntax (System_Boundary, Container_Boundary) Directional relationships (Rel_Down, Rel_Right, Rel_Up, Rel_Left, Rel_Neighbor) Layout constraints (Lay_Right, Lay_Down, Lay_Distance) LAYOUT CONFLICT RULES — critical rules to prevent rendering failures when layout hints contradict relationship directions Tier-based layout patterns Worked examples for Context, Container, and Component diagrams For C4 layout science (Sugiyama algorithm, edge crossing targets, declaration ordering), also see the Mermaid skill's c4-layout-science.md — Section 7 covers PlantUML directional hints. Common Syntax Gotchas These are the most common PlantUML syntax errors encountered when generating diagrams: Gotcha Problem Fix Rel_Down contradicts Lay_Right Layout engine receives conflicting direction hints for the same element pair Ensure every Rel_* direction is consistent with any Lay_* constraint on the same pair Missing @startuml / @enduml Diagram fails to render entirely Always wrap PlantUML code in @startuml and @enduml Wrong !include URL C4 macros not found, syntax errors on Person/System/Container Use exact URL from plantuml-stdlib: https://raw.githubusercontent.com/plantuml-stdlib/C4-PlantUML/master/C4_Context.puml Generic Rel instead of directional Layout engine places elements randomly without direction hints Always use Rel_Down , Rel_Right , etc. instead of plain Rel Missing element declaration Relationship references an undeclared element ID Declare ALL elements before ANY relationships Spaces in element IDs Parser fails on IDs with spaces or special characters Use camelCase or underscores: paymentApi , payment_api Nested boundaries without content Empty boundaries may cause rendering errors Ensure every boundary contains at least one element \n in descriptions Expects literal \n text but PlantUML renders it as a line break This is expected behavior — PlantUML interprets \n as line breaks natively. Use \\n if literal text is needed ArcKit Integration This skill handles conversational PlantUML syntax questions — quick lookups, syntax examples, troubleshooting rendering issues, and learning about diagram types. For formal architecture diagram generation with document control, project integration, layout science, and governance compliance, use the /arckit:diagram command instead. It generates versioned diagram artifacts saved to your project directory with full traceability to requirements and architecture principles.