{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "$id": "https://aps-agent.local/schemas/plan_node.schema.json",
  "title": "PlanNode",
  "type": "object",
  "additionalProperties": false,
  "required": [
    "planId",
    "layer",
    "parentId",
    "version",
    "regenCount",
    "inputsHash",
    "status",
    "payload",
    "evidenceRefs",
    "createdAt",
    "createdBy"
  ],
  "properties": {
    "planId": {
      "type": "string",
      "pattern": "^[A-Za-z0-9][A-Za-z0-9_.:-]{0,127}$"
    },
    "layer": {
      "enum": ["L0", "L1", "L2", "L3"]
    },
    "parentId": {
      "type": ["string", "null"]
    },
    "version": {
      "type": "integer",
      "minimum": 1
    },
    "regenCount": {
      "type": "integer",
      "minimum": 0
    },
    "inputsHash": {
      "type": "string",
      "pattern": "^[0-9a-f]{64}$"
    },
    "status": {
      "enum": ["DRAFT", "APPROVED", "RUNNING", "DONE", "FAILED", "SUPERSEDED"]
    },
    "payload": {},
    "evidenceRefs": {
      "type": "array",
      "items": {"type": "string"}
    },
    "createdAt": {
      "type": "string",
      "minLength": 1
    },
    "createdBy": {
      "enum": ["LLM", "USER", "SYSTEM"]
    }
  }
}