{
  "id": "skill-validator",
  "title": "SKILL.md Validator and Loader",
  "level": 1,
  "levelName": "Starter",
  "tagline": "Validate skill metadata and load only the context the task needs.",
  "summary": "Build a bounded Agent Skills loader with a deliberately small frontmatter grammar, strict metadata validation, safe reference paths, and progressive disclosure. The supported YAML subset is explicit; unsupported forms fail instead of being guessed.",
  "usefulFor": [
    "A compatibility linter explaining why a skill works in one agent but fails in another.",
    "The parser accepts plain single-line values and JSON-compatible quoted strings."
  ],
  "youWillBuild": "A compatibility linter explaining why a skill works in one agent but fails in another.",
  "hours": 8,
  "languages": [
    "Rust"
  ],
  "status": "ready",
  "source": "core",
  "author": {
    "name": "AI Engineering from Scratch",
    "github": "rohitg00"
  },
  "skills": [
    "Parse an explicit frontmatter subset",
    "Validate names and descriptions",
    "Contain resource paths",
    "Load context within a character budget"
  ],
  "prerequisites": [
    {
      "title": "Data management",
      "path": "phases/00-setup-and-tooling/09-data-management"
    },
    {
      "title": "Structured outputs",
      "path": "phases/11-llm-engineering/03-structured-outputs"
    }
  ],
  "inspiredBy": [],
  "demo": {
    "command": [
      "python3",
      "demo.py"
    ],
    "cwd": "solution"
  },
  "stages": [
    {
      "id": "01-parse-an-explicit-frontmatter-subset",
      "title": "Parse an explicit frontmatter subset",
      "summary": "Split only a leading --- block.",
      "hours": 2,
      "language": "rust",
      "difficulty": "starter",
      "concepts": [
        "Header boundary",
        "Key split",
        "Duplicate gate",
        "Body retained"
      ]
    },
    {
      "id": "02-validate-names-and-descriptions",
      "title": "Validate names and descriptions",
      "summary": "The loader accepts only lowercase names of 1 to 64 bytes with single interior hyphens, no leading digit restriction, and a nonblank description up to 1024 characters.",
      "hours": 2,
      "language": "rust",
      "difficulty": "core",
      "concepts": [
        "Read fields",
        "Name grammar",
        "Folder identity",
        "Typed skill"
      ]
    },
    {
      "id": "03-contain-resource-paths",
      "title": "Contain resource paths",
      "summary": "Resolve resource names relative to a skill root.",
      "hours": 2,
      "language": "rust",
      "difficulty": "core",
      "concepts": [
        "Relative input",
        "Component gate",
        "Canonicalize",
        "Containment"
      ]
    },
    {
      "id": "04-load-context-within-a-character-budget",
      "title": "Load context within a character budget",
      "summary": "Discovery returns name and description.",
      "hours": 2,
      "language": "rust",
      "difficulty": "core",
      "concepts": [
        "Discover metadata",
        "Choose activation",
        "Count characters",
        "Complete or reject"
      ]
    }
  ],
  "demos": [
    {
      "gif": "media/run.gif",
      "poster": "media/run.png",
      "title": "Initialize and grade",
      "caption": "Recorded starter failure followed by all reference-solution stages passing. Reference passes do not earn learner certificates."
    },
    {
      "gif": "media/output.gif",
      "poster": "media/output.png",
      "title": "Inspect the output",
      "caption": "Actual output from the local deterministic demo command. See the README for fixture and live-adapter limits."
    }
  ]
}