{
  "instruction": "Build a product inventory API with FastAPI",
  "relevant_when": "Agent builds a FastAPI API with CRUD operations, stock management, or resource tracking",
  "context": "Proactively check that agents apply FastAPI error handling best practices when building resource management APIs, even when not explicitly asked to add error handling.",
  "sources": [
    {
      "type": "file",
      "filename": "skills/fastapi-error-handling/SKILL.md",
      "tile": "tessl-labs/fastapi-error-handling"
    }
  ],
  "checklist": [
    {
      "name": "custom-exceptions",
      "rule": "Agent defines custom exception classes (e.g. NotFoundError, ConflictError) rather than bare HTTPException",
      "relevant_when": "Agent builds a FastAPI application with domain errors"
    },
    {
      "name": "exception-handler-registered",
      "rule": "Agent registers @app.exception_handler for custom exception types returning structured JSON",
      "relevant_when": "Agent builds a FastAPI application"
    },
    {
      "name": "validation-error-handler",
      "rule": "Agent registers @app.exception_handler(RequestValidationError) with per-field structured error details",
      "relevant_when": "Agent builds a FastAPI app that accepts request bodies"
    },
    {
      "name": "generic-exception-handler",
      "rule": "Agent registers @app.exception_handler(Exception) that returns a safe generic message and logs the real error",
      "relevant_when": "Agent builds a FastAPI application"
    },
    {
      "name": "consistent-error-format",
      "rule": "All errors use the same JSON shape with a code/type and message, across business rule violations, validation errors, and not-found errors",
      "relevant_when": "Agent returns error responses from FastAPI"
    }
  ]
}