Backend

Production-ready FastAPI project scaffolding templates including directory structure, configuration files, settings management, dependency injection, MCP server integration, and development/production setup patterns. Use when creating FastAPI projects, setting up project structure, configuring FastAPI applications, implementing settings management, adding MCP integration, or when user mentions FastAPI setup, project scaffold, app configuration, environment management, or backend structure.

Set up GPU sandboxes for interpretability research. Use when writing setup.py scripts with Sandbox, SandboxConfig, ModelConfig, or create_notebook_session. Provides the exact API for Modal GPU environments - MUST read before writing any sandbox setup code.

Guide for creating high-quality MCP (Model Context Protocol) servers that enable LLMs to interact with external services. Use when building MCP servers to integrate APIs, whether in Python (FastMCP) or Node/TypeScript (MCP SDK).

Introduce test-driven development to beginners with simple Flask/Sinatra test examples and TDD concepts

Extracts HTTP/HTTPS request and response data from Charles Proxy session files (.chlsj format), including URLs, methods, status codes, headers, request bodies, and response bodies. Use when analyzing captured network traffic from Charles Proxy debug sessions, inspecting API calls, debugging HTTP requests, or examining proxy logs.

FastAPI Python backend in api/. Covers routes, models, Supabase integration, authentication, R2 storage, and Cloudflare Workers deployment. Port 9999 for local dev. OpenAPI docs at /docs.

Diagnose and solve common beginner programming mistakes in Flask or Sinatra

Expert knowledge on creating Claude Code subagents. Use when designing or creating subagent .md files, understanding subagent structure, tool restrictions, or model selection.

Use when writing Rails models - enforces state-as-records not booleans, concerns as adjectives namespaced under model, invocation ordering, and private indentation

Automatically troubleshoot unexpected results OR command/script errors without user request. Triggers when: (1) unexpected behavior - command succeeded but expected effect didn't happen, missing expected errors, wrong output, silent failures; (2) explicit failures - stderr, exceptions, non-zero exit, SDK/API errors. Applies systematic diagnosis using error templates, hypothesis testing, and web research for any Stack Overflow-worthy issue.

WHEN: Rust project review, ownership/borrowing, error handling, unsafe code, performanceWHAT: Ownership patterns + Lifetime analysis + Error handling (Result/Option) + Unsafe audit + Idiomatic RustWHEN NOT: Rust API → rust-api-reviewer, Go → go-reviewer

Mathematical calculation skill for computing arithmetic expressions, trigonometry, logarithms, and complex math. Use EXCLUSIVELY for math calculations: sin, cos, tan, sqrt, log, exponents, etc.

Test n8n nodes using Jest, nock for HTTP mocking, and local testing workflows with npm link. Use this skill when writing test files in __tests__ folders, mocking HTTP requests with nock, creating mock IExecuteFunctions contexts, testing helper functions, setting up golden file tests, running the linter before publishing, or locally testing nodes in the n8n UI. Apply when organizing test files, mocking external APIs, validating node execution output, or following the pre-publish checklist.

Generate and edit images using the Gemini API (Nano Banana). Use this skill when creating images from text prompts, editing existing images, applying style transfers, generating logos with text, creating stickers, product mockups, or any image generation/manipulation task. Supports text-to-image, image editing, multi-turn refinement, and composition from multiple reference images.

Data import/export and validation pipeline for MyDetailArea. Handles bulk operations, CSV/Excel processing, data migration, validation rules, error handling, and audit trails. Supports vehicle inventory import, order batch updates, contact imports, and custom data transformations. Use when implementing bulk data operations, migration from legacy systems, or scheduled exports.

Integrate templ components with Go HTTP server using net/http. Use when connecting templ to web server, creating HTTP handlers, mentions 'templ server', 'HTTP routes', or 'serve templ components'.

Generate API documentation from TypeScript source code for RSPress. Use when documenting package APIs, extracting types from source code, or creating function/class reference pages.

Escape from Tarkov game domain knowledge for EFT-Tracker. Understands quest structures, traders, Kappa container progression, and tarkov.dev API integration. Activates when user mentions: quest, trader, Kappa, task, hideout, PMC, SCAV, Tarkov, wipe, progression, locked, available, completed.

Research external information using web search and codebase exploration. Activate when user requests research or asks about libraries, APIs, external repos, current events, or needs up-to-date information. Delegates to subagents to preserve context window.

Recognize when user wants a second opinion from another AI (Codex, Gemini, GLM). Asks for confirmation before calling external APIs. Triggers on phrases like "second opinion", "what would GPT say", "ask Gemini", "compare with Codex".