{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "$id": "https://xbrief.dev/schemas/xbrief-core-0.8.schema.json",
  "title": "xBRIEF Core Schema v0.8",
  "description": "JSON Schema for xBRIEF core document structure (v0.8). Adds PlanItem type (task/group/milestone/epic), summary, planRefs, extension property namespace (x-<consumer>/), Source/Confidence narrative keys, and reference type registry.",
  "type": "object",
  "required": [
    "xBRIEFInfo",
    "plan"
  ],
  "properties": {
    "xBRIEFInfo": {
      "$ref": "#/$defs/xBRIEFInfo"
    },
    "plan": {
      "$ref": "#/$defs/Plan"
    }
  },
  "additionalProperties": true,
  "patternProperties": {
    "^x-[a-z0-9-]+/": {
      "description": "Extension property. Consumer-scoped; MUST be preserved verbatim on round-trip."
    }
  },
  "not": {
    "anyOf": [
      {
        "required": [
          "todoList"
        ]
      },
      {
        "required": [
          "playbook"
        ]
      }
    ]
  },
  "$defs": {
    "xBRIEFInfo": {
      "type": "object",
      "required": [
        "version"
      ],
      "properties": {
        "version": {
          "type": "string",
          "const": "0.8"
        },
        "author": {
          "type": "string"
        },
        "description": {
          "type": "string"
        },
        "metadata": {
          "type": "object"
        },
        "created": {
          "$ref": "#/$defs/dateTime"
        },
        "updated": {
          "$ref": "#/$defs/dateTime"
        },
        "timezone": {
          "type": "string"
        }
      },
      "additionalProperties": true,
      "patternProperties": {
        "^x-[a-z0-9-]+/": {}
      }
    },
    "Plan": {
      "type": "object",
      "required": [
        "title",
        "status",
        "items"
      ],
      "properties": {
        "id": {
          "type": "string",
          "pattern": "^[a-zA-Z0-9_-]+(\\.[a-zA-Z0-9_-]+)*$"
        },
        "uid": {
          "type": "string"
        },
        "title": {
          "type": "string",
          "minLength": 1
        },
        "status": {
          "$ref": "#/$defs/PlanStatus"
        },
        "items": {
          "type": "array",
          "items": {
            "$ref": "#/$defs/PlanItem"
          }
        },
        "narratives": {
          "type": "object",
          "properties": {
            "Proposal": {
              "type": "string"
            },
            "Overview": {
              "type": "string"
            },
            "Background": {
              "type": "string"
            },
            "Problem": {
              "type": "string"
            },
            "Constraint": {
              "type": "string"
            },
            "Hypothesis": {
              "type": "string"
            },
            "Alternative": {
              "type": "string"
            },
            "Risk": {
              "type": "string"
            },
            "Test": {
              "type": "string"
            },
            "Action": {
              "type": "string"
            },
            "Observation": {
              "type": "string"
            },
            "Result": {
              "type": "string"
            },
            "Reflection": {
              "type": "string"
            },
            "Outcome": {
              "type": "string"
            },
            "Strengths": {
              "type": "string"
            },
            "Weaknesses": {
              "type": "string"
            },
            "Lessons": {
              "type": "string"
            },
            "Source": {
              "type": "string",
              "description": "How a fact was established. Recommended values: verified:<method>, observed:<method>, inferred:<reason>, assumed."
            },
            "Confidence": {
              "type": "string",
              "description": "Agent certainty level. Recommended values: high, medium, low."
            }
          },
          "additionalProperties": {
            "type": "string"
          }
        },
        "edges": {
          "type": "array",
          "items": {
            "$ref": "#/$defs/Edge"
          }
        },
        "tags": {
          "type": "array",
          "items": {
            "type": "string"
          }
        },
        "metadata": {
          "type": "object"
        },
        "created": {
          "$ref": "#/$defs/dateTime"
        },
        "updated": {
          "$ref": "#/$defs/dateTime"
        },
        "author": {
          "type": "string"
        },
        "reviewers": {
          "type": "array",
          "items": {
            "type": "string"
          }
        },
        "uris": {
          "type": "array",
          "items": {
            "$ref": "#/$defs/URI"
          }
        },
        "references": {
          "type": "array",
          "items": {
            "$ref": "#/$defs/VBriefReference"
          }
        },
        "timezone": {
          "type": "string"
        },
        "agent": {
          "$ref": "#/$defs/Agent"
        },
        "lastModifiedBy": {
          "$ref": "#/$defs/Agent"
        },
        "changeLog": {
          "type": "array",
          "items": {
            "$ref": "#/$defs/Change"
          }
        },
        "sequence": {
          "type": "integer",
          "minimum": 0
        },
        "fork": {
          "$ref": "#/$defs/Fork"
        }
      },
      "additionalProperties": true,
      "patternProperties": {
        "^x-[a-z0-9-]+/": {}
      }
    },
    "PlanItem": {
      "type": "object",
      "required": [
        "title",
        "status"
      ],
      "properties": {
        "id": {
          "type": "string",
          "pattern": "^[a-zA-Z0-9_-]+(\\.[a-zA-Z0-9_-]+)*$"
        },
        "uid": {
          "type": "string"
        },
        "type": {
          "type": "string",
          "enum": ["task", "group", "milestone", "epic"],
          "default": "task",
          "description": "Item type. Containers (group, milestone, epic) support status rollup."
        },
        "summary": {
          "type": "string",
          "description": "Single-sentence shorthand description. Equivalent to narrative.Overview when narrative is absent."
        },
        "title": {
          "type": "string",
          "minLength": 1
        },
        "status": {
          "$ref": "#/$defs/PlanItemStatus"
        },
        "narrative": {
          "type": "object",
          "additionalProperties": {
            "type": "string"
          }
        },
        "subItems": {
          "type": "array",
          "description": "Deprecated legacy alias for items; retained for compatibility.",
          "items": {
            "$ref": "#/$defs/PlanItem"
          }
        },
        "planRef": {
          "type": "string",
          "pattern": "^(#[a-zA-Z0-9_.-]+|file://.*|https://.*)$"
        },
        "planRefs": {
          "type": "array",
          "description": "Array of plan reference URIs for container items aggregating multiple external xBRIEFs.",
          "items": {
            "type": "string",
            "pattern": "^(#[a-zA-Z0-9_.-]+|file://.*|https://.*)$"
          }
        },
        "tags": {
          "type": "array",
          "items": {
            "type": "string"
          }
        },
        "metadata": {
          "type": "object"
        },
        "created": {
          "$ref": "#/$defs/dateTime"
        },
        "updated": {
          "$ref": "#/$defs/dateTime"
        },
        "completed": {
          "$ref": "#/$defs/dateTime"
        },
        "priority": {
          "enum": [
            "low",
            "medium",
            "high",
            "critical"
          ]
        },
        "effort": {
          "type": "string",
          "enum": ["S", "M", "L", "XL"],
          "description": "Optional effort estimate with time anchors: S <2h, M half-day (2-4h), L 1-2 days, XL needs breakdown into S/M/L before activation. Omitted items still validate."
        },
        "dueDate": {
          "$ref": "#/$defs/dateTime"
        },
        "startDate": {
          "$ref": "#/$defs/dateTime"
        },
        "endDate": {
          "$ref": "#/$defs/dateTime"
        },
        "percentComplete": {
          "type": "number",
          "minimum": 0,
          "maximum": 100
        },
        "participants": {
          "type": "array",
          "items": {
            "$ref": "#/$defs/Participant"
          }
        },
        "location": {
          "$ref": "#/$defs/Location"
        },
        "uris": {
          "type": "array",
          "items": {
            "$ref": "#/$defs/URI"
          }
        },
        "recurrence": {
          "$ref": "#/$defs/RecurrenceRule"
        },
        "reminders": {
          "type": "array",
          "items": {
            "$ref": "#/$defs/Reminder"
          }
        },
        "classification": {
          "enum": [
            "public",
            "private",
            "confidential"
          ]
        },
        "relatedComments": {
          "type": "array",
          "items": {
            "type": "string"
          }
        },
        "timezone": {
          "type": "string"
        },
        "sequence": {
          "type": "integer",
          "minimum": 0
        },
        "lastModifiedBy": {
          "$ref": "#/$defs/Agent"
        },
        "lockedBy": {
          "$ref": "#/$defs/Lock"
        },
        "items": {
          "type": "array",
          "description": "Preferred v0.6 nested PlanItem field.",
          "items": {
            "$ref": "#/$defs/PlanItem"
          }
        }
      },
      "additionalProperties": true,
      "patternProperties": {
        "^x-[a-z0-9-]+/": {}
      }
    },
    "PlanStatus": {
      "enum": [
        "draft",
        "proposed",
        "approved",
        "pending",
        "running",
        "completed",
        "blocked",
        "failed",
        "cancelled"
      ],
      "description": "Status values valid at plan level. 'auto' is excluded — it is only valid on container PlanItems with children."
    },
    "PlanItemStatus": {
      "enum": [
        "draft",
        "proposed",
        "approved",
        "pending",
        "running",
        "completed",
        "blocked",
        "failed",
        "cancelled",
        "auto"
      ],
      "description": "Status values valid on PlanItems. 'auto' rolls up from children and is valid only on container items (group/milestone/epic) with children."
    },
    "Edge": {
      "type": "object",
      "required": [
        "from",
        "to",
        "type"
      ],
      "properties": {
        "from": {
          "type": "string",
          "pattern": "^[a-zA-Z0-9_-]+(\\.[a-zA-Z0-9_-]+)*$"
        },
        "to": {
          "type": "string",
          "pattern": "^[a-zA-Z0-9_-]+(\\.[a-zA-Z0-9_-]+)*$"
        },
        "type": {
          "type": "string",
          "description": "Core types: blocks, informs, invalidates, suggests. Custom types allowed."
        }
      },
      "additionalProperties": true
    },
    "Participant": {
      "type": "object",
      "required": [
        "id",
        "role"
      ],
      "properties": {
        "id": {
          "type": "string"
        },
        "name": {
          "type": "string"
        },
        "email": {
          "type": "string"
        },
        "role": {
          "enum": [
            "owner",
            "assignee",
            "reviewer",
            "observer",
            "contributor"
          ]
        },
        "status": {
          "enum": [
            "accepted",
            "declined",
            "tentative",
            "needsAction"
          ]
        }
      },
      "additionalProperties": true
    },
    "URI": {
      "type": "object",
      "required": [
        "uri"
      ],
      "properties": {
        "uri": {
          "type": "string"
        },
        "description": {
          "type": "string"
        },
        "type": {
          "type": "string"
        },
        "title": {
          "type": "string"
        },
        "tags": {
          "type": "array",
          "items": {
            "type": "string"
          }
        }
      },
      "additionalProperties": true
    },
    "VBriefReference": {
      "allOf": [
        {
          "$ref": "#/$defs/URI"
        },
        {
          "type": "object",
          "required": [
            "uri",
            "type"
          ],
          "properties": {
            "type": {
              "type": "string",
              "pattern": "^x-[a-zA-Z0-9_-]+/",
              "description": "A xBRIEF reference type. Canonical types: x-xbrief/plan, x-xbrief/github-issue, x-xbrief/github-pr, x-xbrief/commit, x-xbrief/external, x-xbrief/research, x-xbrief/adr. Custom consumer types SHOULD use x-<consumer>/ namespace (e.g. x-myapp/ticket)."
            }
          }
        }
      ]
    },
    "Location": {
      "type": "object",
      "properties": {
        "name": {
          "type": "string"
        },
        "address": {
          "type": "string"
        },
        "geo": {
          "type": "array",
          "minItems": 2,
          "maxItems": 2,
          "items": {
            "type": "number"
          }
        },
        "url": {
          "type": "string"
        }
      },
      "additionalProperties": true
    },
    "RecurrenceRule": {
      "type": "object",
      "required": [
        "frequency"
      ],
      "properties": {
        "frequency": {
          "enum": [
            "daily",
            "weekly",
            "monthly",
            "yearly"
          ]
        },
        "interval": {
          "type": "integer",
          "minimum": 1
        },
        "until": {
          "$ref": "#/$defs/dateTime"
        },
        "count": {
          "type": "integer",
          "minimum": 1
        },
        "byDay": {
          "type": "array",
          "items": {
            "enum": [
              "MO",
              "TU",
              "WE",
              "TH",
              "FR",
              "SA",
              "SU"
            ]
          }
        },
        "byMonth": {
          "type": "array",
          "items": {
            "type": "integer",
            "minimum": 1,
            "maximum": 12
          }
        },
        "byMonthDay": {
          "type": "array",
          "items": {
            "type": "integer",
            "minimum": 1,
            "maximum": 31
          }
        }
      },
      "additionalProperties": true
    },
    "Reminder": {
      "type": "object",
      "required": [
        "trigger",
        "action"
      ],
      "properties": {
        "trigger": {
          "type": "string"
        },
        "action": {
          "enum": [
            "display",
            "email",
            "webhook",
            "audio"
          ]
        },
        "description": {
          "type": "string"
        }
      },
      "additionalProperties": true
    },
    "Agent": {
      "type": "object",
      "required": [
        "id",
        "type"
      ],
      "properties": {
        "id": {
          "type": "string"
        },
        "type": {
          "enum": [
            "human",
            "aiAgent",
            "system"
          ]
        },
        "name": {
          "type": "string"
        },
        "email": {
          "type": "string"
        },
        "model": {
          "type": "string"
        },
        "version": {
          "type": "string"
        }
      },
      "additionalProperties": true
    },
    "Change": {
      "type": "object",
      "required": [
        "sequence",
        "timestamp",
        "agent",
        "operation"
      ],
      "properties": {
        "sequence": {
          "type": "integer",
          "minimum": 0
        },
        "timestamp": {
          "$ref": "#/$defs/dateTime"
        },
        "agent": {
          "$ref": "#/$defs/Agent"
        },
        "operation": {
          "enum": [
            "create",
            "update",
            "delete",
            "fork",
            "merge"
          ]
        },
        "reason": {
          "type": "string"
        },
        "path": {
          "type": "string"
        },
        "oldValue": {},
        "newValue": {},
        "description": {
          "type": "string"
        },
        "snapshotUri": {
          "type": "string"
        },
        "relatedChanges": {
          "type": "array",
          "items": {
            "type": "string"
          }
        }
      },
      "additionalProperties": true
    },
    "Fork": {
      "type": "object",
      "required": [
        "parentUid",
        "parentSequence",
        "forkedAt"
      ],
      "properties": {
        "parentUid": {
          "type": "string"
        },
        "parentSequence": {
          "type": "integer",
          "minimum": 0
        },
        "forkedAt": {
          "$ref": "#/$defs/dateTime"
        },
        "forkReason": {
          "type": "string"
        },
        "mergeStatus": {
          "enum": [
            "unmerged",
            "mergePending",
            "merged",
            "conflict"
          ]
        }
      },
      "additionalProperties": true
    },
    "Lock": {
      "type": "object",
      "required": [
        "agent",
        "acquiredAt",
        "type"
      ],
      "properties": {
        "agent": {
          "$ref": "#/$defs/Agent"
        },
        "acquiredAt": {
          "$ref": "#/$defs/dateTime"
        },
        "expiresAt": {
          "$ref": "#/$defs/dateTime"
        },
        "type": {
          "enum": [
            "soft",
            "hard"
          ]
        }
      },
      "additionalProperties": true
    },
    "dateTime": {
      "type": "string",
      "format": "date-time",
      "pattern": "(Z|[+-]\\d{2}:\\d{2})$"
    }
  }
}