Write production-quality Mermaid diagrams following modern best practices. Use this skill whenever the user asks to write, review, fix, or generate Mermaid diagrams, flowcharts, sequence diagrams, class diagrams, state diagrams, ER diagrams, Gantt charts, or any Mermaid-supported diagram type. Also trigger when the user mentions "mermaid", "diagram as code", "flowchart", "sequence diagram", "class diagram", "state diagram", "ER diagram", "Gantt chart", "pie chart", "mindmap", "timeline", "gitgraph", "C4 diagram", "sankey", "block diagram", "kanban", "architecture diagram", or asks to visualize, diagram, or chart anything using text-based syntax. Even if the user just says "draw this flow" or "diagram this architecture", use this skill — it covers all Mermaid authoring. Trigger when writing markdown that includes diagrams or when the user provides `.md` or `.mermaid` files.
Perform all Domain-Driven Design tasks: strategic design (subdomains, bounded contexts, context maps, ubiquitous language), tactical design (entities, value objects, aggregates, domain events, repositories, domain services, factories), and collaborative modeling (Event Storming, bounded context canvas). Use this skill whenever the user mentions "DDD", "domain-driven", "bounded context", "aggregate", "value object", "domain event", "context map", "subdomain", "core domain", "anti-corruption layer", "event storming", "domain model", "aggregate root", or asks to decompose a system, identify service boundaries, model a business domain, design aggregates, or map context relationships. Also trigger for "how should I split this monolith", "where do I draw the boundaries", "model this domain", "help me understand this business domain", or upstream/downstream team relationships. Covers all DDD activities from strategic analysis through tactical implementation.
Use this skill whenever a required tool, binary, library, or dependency is missing from the current machine. Trigger when you encounter "command not found", missing package errors, unavailable system dependencies, or when the user explicitly says mention nix. Also trigger when the user asks you to create or maintain a flake.nix, set up a reproducible dev environment, or wrap a project in a Nix flake. If you already tried to install something with apt/brew/pip and it failed or is unavailable, and the user tells you to use nix instead, this is your skill. Do NOT trigger for NixOS system configuration, home-manager, or deploying NixOS machines — only for using nix as a dependency/tooling provider.
Run structured Example Mapping sessions that produce specification briefs from rough capability descriptions. Use this skill whenever the user wants to discover business rules, explore edge cases, surface acceptance criteria, or prepare a capability for Gherkin specification. Also trigger when the user mentions "example mapping", "example map", "three amigos", "discovery session", "specification discovery", "rules and examples", "what are the acceptance criteria", or asks to "brainstorm the behavior" of a feature. Trigger even when the user says "what should this feature do", "help me think through the rules", "what are the edge cases", or "is this ready for spec". This skill covers the entire discovery conversation from rough idea to structured specification brief. It is the upstream step before Gherkin formulation — use it before the gherkin skill, not instead of it. When agents or workflows need to explore a capability before writing .feature files, this skill provides the structured conversation format.
Write production-quality Gherkin `.feature` files that follow all modern best practices. Use this skill whenever the user asks to write, review, fix, or generate Gherkin scenarios, Cucumber feature files, BDD specifications, acceptance criteria in Given/When/Then format, or anything involving `.feature` files. Also trigger when the user mentions "BDD", "behaviour-driven", "behavior-driven", "Given/When/Then", "scenario outline", "feature file", "acceptance test scenarios", "executable specification", or asks to convert requirements/user stories into Gherkin. Even if the user just says "write tests for this feature" or "turn these requirements into scenarios", use this skill — it covers all Gherkin authoring.
Use when the user says "ticket", "issue", "board", "backlog", "status", "blocked", "depends on", references a ticket number like "#12", or asks about work status. Also use proactively: when starting implementation (move the ticket to "In progress"), when opening PRs (suggest "Closes #N"), when design reveals new needs (suggest sub-issues), when a ticket depends on another (add a dependency relationship), or when a feature is done (move to "Done"). Trigger whenever GitHub Projects, issue tracking, milestones, labels, dependencies, sub-issues, or workflow status boards are relevant — even if the user doesn't say "ticket" explicitly.