{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "$id": "https://github.com/mieweb/pulsevault/blob/main/protocol/schemas/capabilities.schema.json",
  "title": "GET /capabilities response",
  "description": "Unauthenticated discovery (PROTOCOL.md §2). A client reads it before pairing and pairs only if its protocol range overlaps [minSupportedVersion, maxSupportedVersion]. Clients must ignore fields they don't recognize.",
  "type": "object",
  "required": [
    "protocolVersion",
    "protocolRevision",
    "minSupportedVersion",
    "maxSupportedVersion",
    "kinds",
    "allowedExtensions",
    "maxUploadSize",
    "checksum"
  ],
  "properties": {
    "protocolVersion": {
      "type": "integer",
      "minimum": 1,
      "description": "Protocol major this server implements. Also sent as the `Protocol-Version` header on every response."
    },
    "protocolRevision": {
      "type": "string",
      "pattern": "^[0-9]+\\.[0-9]+$",
      "description": "Spec revision this server implements, `major.minor`. The minor counts additions older clients can ignore."
    },
    "minSupportedVersion": {
      "type": "integer",
      "minimum": 1,
      "description": "Oldest protocol major this server accepts. Clients whose newest protocol is older get 426 Upgrade Required."
    },
    "maxSupportedVersion": {
      "type": "integer",
      "minimum": 1,
      "description": "Newest protocol major this server accepts."
    },
    "kinds": {
      "type": "array",
      "items": { "type": "string", "enum": ["video", "project", "captions", "thumbnail"] },
      "description": "Artifact kinds this server accepts."
    },
    "allowedExtensions": {
      "type": "object",
      "additionalProperties": { "type": "array", "items": { "type": "string" } },
      "description": "Allowed file extensions per kind, lowercase with the leading dot."
    },
    "maxUploadSize": {
      "type": "number",
      "description": "Largest artifact the server accepts, in bytes."
    },
    "checksum": {
      "type": "object",
      "required": ["algorithms"],
      "properties": {
        "algorithms": { "type": "array", "items": { "type": "string" } }
      },
      "description": "Checksum algorithms accepted in `Upload-Metadata.checksum`."
    },
    "viewLinks": {
      "type": "boolean",
      "description": "Whether `POST {prefix}/artifacts/<id>/view-link` mints read-only view links (§6.4). Absent before protocol 2.2, which a client treats as false."
    }
  }
}