{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "$id": "https://api-evangelist.github.io/knowledge/json-schema/knowledge-signal-schema.json",
  "title": "API Knowledge Signal",
  "description": "A single observed signal about an API or its provider — a number, a category, or a tag — sourced from a third-party index (GitHub, Naftiko Signals, job boards, blogs).",
  "type": "object",
  "required": ["type", "value", "source"],
  "properties": {
    "type": {
      "type": "string",
      "description": "Kind of signal."
    },
    "value": {
      "description": "Signal value; left untyped because signal types vary (boolean, number, string, array)."
    },
    "unit": {
      "type": "string",
      "description": "Optional unit (e.g. 'count', 'days', 'percent')."
    },
    "source": {
      "type": "string",
      "format": "uri"
    },
    "observed": {
      "type": "string",
      "format": "date-time"
    },
    "decay": {
      "type": "string",
      "description": "Optional ISO-8601 duration after which this signal should be considered stale (e.g. 'P30D')."
    }
  },
  "additionalProperties": false
}