{
  "$schema": "http://json-schema.org/draft-07/schema#",
  "$ref": "#/definitions/AxmPackageMeta",
  "definitions": {
    "ExtensionFqn": {
      "type": "string",
      "pattern": "^(@[a-z0-9_](?:[a-z0-9_-]*[a-z0-9_])?)\\/(skills|mcps|subagents|rules|hooks|knowledge|packs)\\/([a-z0-9](?:[a-z0-9-]{0,62}[a-z0-9])?)$",
      "title": "Extension FQN",
      "description": "Canonical extension identifier in @owner/<type>s/<name> form.",
      "examples": ["@acme/skills/code-review", "@my-org/rules/typescript"]
    },
    "VersionRange": {
      "type": "string",
      "minLength": 1,
      "pattern": "^[~^<>=*xXvV0-9A-Za-z+| .-]+$",
      "title": "Version Range",
      "description": "A semver version range like ^1.0.0, ~2.3.0, >=1.0.0 <3.0.0, or an exact version 1.2.3. Use \"*\" to always resolve to the latest available version.",
      "examples": ["^1.0.0", "~2.4", ">=1 <3", "1.2.3", "*"]
    },
    "PackageExtensionDeclaration": {
      "type": "object",
      "properties": {
        "ref": { "$ref": "#/definitions/ExtensionFqn" },
        "versionRange": {
          "anyOf": [
            { "anyOf": [{ "$ref": "#/definitions/VersionRange" }, { "type": "null" }] },
            { "type": "null" }
          ]
        }
      },
      "required": ["ref"],
      "additionalProperties": false,
      "title": "Package Extension Declaration",
      "description": "An extension declared by package-native AXM metadata, with an optional semver version range."
    },
    "AxmPackageMeta": {
      "type": "object",
      "properties": {
        "$schema": { "anyOf": [{ "type": "string" }, { "type": "null" }] },
        "extensions": {
          "type": "array",
          "items": { "$ref": "#/definitions/PackageExtensionDeclaration" }
        }
      },
      "required": ["extensions"],
      "additionalProperties": false,
      "title": "axm Package Metadata",
      "description": "Recommendation metadata shipped by library authors to surface axm extensions."
    }
  }
}