Software Development Skills

Evaluates object-oriented designs to choose composition, inheritance, or algebraic data types. Produces decision rationales, refactoring plans, and review guardrails that reduce fragile base classes and subclass explosion. Use when reviewing class hierarchies, deciding between extends vs interfaces, refactoring inheritance-heavy code, introducing dependency-injected collaborators, or defining team conventions for object modeling.

Applies and reviews professional typography rules based on Butterick's Practical Typography. Covers characters and symbols (curly quotes, dashes, ellipses, nonbreaking spaces), text formatting (bold/italic, caps, kerning, letterspacing, color), body text settings (point size, line spacing, line length, indents, hyphenation), page layout (margins, headings, tables, lists, columns), font selection (professional vs system fonts, mixing, alternate figures), and document-specific guidance (emails, presentations, résumés, research papers, business cards, letterhead, websites). Use when generating or reviewing text for documents, web pages, presentations, or any formatted output, when the user asks about typography rules, when checking for common typography mistakes (straight quotes, double spaces, bad fonts, improper dashes), or when setting up document styles and layouts.

Applies TCR (test && commit || revert) discipline as a workflow and guardrail for AI-assisted software development. Sets up TCR scripts, selects revert strategies, integrates with tool-specific hooks, and configures guardrails for autonomous agent loops. Use when implementing test-and-commit-or-revert workflows, adding automatic revert on test failure, setting up agent coding loops with safety nets, enforcing small steps via automatic commit on green and revert on red, or when the user mentions TCR, test && commit || revert, automatic revert on failing tests, or coding loop guardrails.

Designs, reviews, and migrates codebases using Vertical Slice Architecture (VSA) — organizing by business capability instead of technical layer. Produces slice boundaries, folder structures, sharing strategies, and migration plans. Use when designing a new VSA codebase, reviewing an existing VSA codebase for anti-patterns, migrating from layered architecture to vertical slices, deciding slice granularity or folder organization, handling shared code across slices, or when the user mentions vertical slices, feature folders, or organizing by use case.

Guides writing, reviewing, and modifying Arazzo workflow specifications (OpenAPI Initiative standard for multi-step API workflows). Use when creating Arazzo documents from scratch, adding steps or workflows to existing specs, reviewing Arazzo files for correctness, or generating API workflow definitions. Covers document structure, runtime expressions, success criteria, control flow, data threading, reusable components, workflow composition, AI agent integration, and validation.

Performs end-to-end platform scalability assessments using a phased methodology, maturity scoring model, risk classification, and prioritized remediation planning. Produces structured scalability reports with evidence, scorecards, and actionable roadmaps, plus optional executive summaries and incident runbook drafts. Use when evaluating whether a system can handle growth, diagnosing scaling bottlenecks, preparing technical due diligence, designing load or resilience validation plans, or building a scalability improvement strategy.

Sets up, structures, and auto-improves AGENTS.md files for coding agent projects. Bootstraps new AGENTS.md with self-improvement meta-rules, structures sections for clean rule placement, audits and prunes existing files against an instruction budget, performs end-of-session reflection to capture learnings, and proactively proposes AGENTS.md updates when corrections or conventions are discovered mid-session. Use when setting up AGENTS.md, adding auto-improvement to an existing AGENTS.md, pruning or auditing AGENTS.md, performing end-of-session reflection, or when the user mentions auto-improving, self-improving, or maintaining agent instructions.

Builds live parameter tuning panels as floating developer overlays with sliders, toggles, color pickers, dropdowns, and spring controls wired to app values for real-time visual exploration. Selects suitable panel libraries by stack (DialKit, Leva, Tweakpane, lil-gui, native HTML), maps hardcoded values to controls with sensible ranges, adds export/presets, and strips panel code from production builds. Use when users ask to add debug sliders, a variables panel, a tuning panel/GUI, or live tweak controls for animation, styling, layout, typography, color, physics, or chart parameters.

Writes and reviews code comments that preserve non-obvious intent, contracts, invariants, and failure semantics without narrating the code. Uses clear layer placement (interface, implementation, cross-module) and lightweight review checks to keep comments accurate over time. Use when adding or reviewing inline comments, docstrings, API docs, or design notes for behavior that could be misunderstood.

Creates, reviews, and interprets C4 software architecture diagrams (System Context, Container, Component, Dynamic, Deployment). Produces Structurizr DSL or Mermaid C4 diagram code following C4 model best practices. Use when the requested output is explicitly C4, when reviewing existing C4 diagrams for correctness and anti-patterns, when generating Structurizr DSL workspaces, when producing Mermaid C4 diagrams for READMEs, or when using C4 diagrams as context for design decisions, code generation, risk analysis, or onboarding.

Designs backend API error contracts with a REST-default approach using RFC 9457 Problem Details, stable machine-readable codes, retry semantics, validation error payloads, observability, and security-safe messaging. Reviews existing error handling against a binary rubric and proposes concrete fixes. Produces optional artifacts such as errors.yaml entries, Problem Details examples, OpenAPI fragments, and runbook templates. Use when creating or revising backend error responses, auditing API error quality, mapping status/code behavior, or documenting error handling for REST, gRPC, GraphQL, and async services.

Guides designing, reviewing, and refactoring modules for depth — maximizing functionality hidden behind minimal interfaces. Analyzes module boundaries, identifies shallow modules and classitis, applies deep module heuristics (pull complexity downward, define errors out of existence, design for the common case), and produces refactoring plans. Covers information hiding, leaky abstractions, and abstraction boundaries based on Ousterhout's A Philosophy of Software Design. Use when designing module interfaces, reviewing code for shallow abstractions, refactoring pass-through layers, evaluating API surface area, reducing interface complexity, or applying deep module principles at any scale (functions, classes, packages, services, APIs).

Designs and reviews Event Models — the visual blueprint for information systems using events, commands, read models, and screens. Produces structured YAML artifacts (swimlanes, slices, events, commands, read models, Given/When/Then specifications). Use when designing a new system or feature with Event Modeling, reviewing an existing event model for anti-patterns or completeness gaps, defining slices and GWT scenarios, or creating an event model from a system description.

Guides designing, reviewing, and governing RESTful APIs — resource modeling, URL structure, HTTP methods, status codes, error handling (RFC 9457), pagination, versioning, security, authentication, caching, idempotency, bulk operations, async patterns, file uploads, OpenAPI documentation, API-first process, and AI-agent consumers. Use when designing new REST API endpoints, reviewing existing API designs, adopting API-first development, running API design sessions, enforcing API contracts in CI/CD, governing an API program, choosing between REST patterns (cursor vs offset pagination, PUT vs PATCH, polling vs webhooks), writing OpenAPI specs, designing for AI-agent consumers (MCP), or making API evolution and deprecation decisions.

Generates professional slide decks as Marp Markdown from source material (memos, documents, notes, bullet points). Produces assertion-titled, visually consistent presentations with speaker notes, exportable to PDF, PPTX, and HTML via Marp CLI. Use when creating presentations, generating slides, building a slide deck, making a pitch deck, converting a document to a presentation, or when the user mentions Marp, slides, or slide decks.

Guides writing idiomatic, functional-style Kotlin code using built-in language features. Use when asked to write, review, or refactor Kotlin code for immutability, pure functions, sealed types, error handling, collections, coroutines, or functional architecture patterns.

Analyzes existing code and guides new type design to make invalid states unrepresentable using type system techniques such as sum types, newtypes, typestate, branded types, and parse-don't-validate. Use when reviewing code for invalid-state bugs, refactoring types to eliminate impossible states, designing domain models, or applying compile-time correctness patterns. Language-agnostic.

Summarizes Markdown files section-by-section with strict sentence budgets derived from source section length. Use when you need deterministic per-section summary quotas, inventory-first workflows, and mechanical verification that each section has exactly floor(sqrt(n)) summary sentences.

Generates, reviews, and fixes Mermaid-only sequence diagrams following syntax rules and best practices. Use when creating Mermaid sequence diagrams from system descriptions, reviewing existing Mermaid sequence diagrams for correctness, fixing parse errors, or refactoring large Mermaid sequence diagrams into focused sub-diagrams. Covers participants, arrows, activations, control flow, notes, styling, and common anti-patterns.

Guides setting up, configuring, and organizing Obsidian vaults for software engineers — folder structure, plugins, templates, Git backup, Dataview queries, and AI integrations. Also creates and edits Obsidian vault files following best practices for frontmatter schemas, wikilinks, Templater syntax, Dataview code blocks, and Canvas JSON. Use when setting up a new vault, recommending plugins, creating note templates, writing Dataview queries, configuring Git sync, advising on vault organization, or generating Obsidian-compatible Markdown files.

Writes property-based tests using Kotest's kotest-property module. Identifies testable properties, designs generators, and configures PBT for Kotlin/JVM projects. Use when writing property-based tests, creating custom Arb generators, choosing property patterns (roundtrip, invariant, idempotence, oracle), debugging shrunk counterexamples, or integrating PBT into a Kotlin test suite alongside example-based tests.

Administers a structured comprehension quiz on a scoped code change to verify the reviewer genuinely understands it before approving or merging. Generates 5–7 questions in three batched rounds using a fixed rubric (restatement, alternatives, invariant, failure-mode, scope, targeted trickiest lines), grades strictly, provides context without revealing answers on failures, and loops until the user passes. Use when the user wants to be quizzed on a diff, wants to verify their understanding before merging or approving AI-generated code, wants a comprehension check before approving, or says things like "quiz me on this change", "test my understanding of this diff", "quiz before approve", or "quiz me before I merge.

Analyzes a codebase scope for coupling issues, diagnoses coupling types using the Connascence framework, and proposes a comprehensive refactoring plan with concrete code changes. Use when asked to find coupling, reduce dependencies, decouple modules, or improve modularity in a codebase.

Generates clean, readable general-purpose diagrams from text DSLs (Mermaid, D2, Graphviz, PlantUML), chooses suitable layout engines, and runs validation/render loops to produce embeddable SVG/PNG/Markdown outputs. Use when a user asks for a flowchart, ERD, state machine, dependency graph, mindmap, network graph, architecture sketch, or basic sequence diagram that must render reliably. Not for explicit C4 modeling or deep Mermaid sequence-specific syntax work.