{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "$id": "https://schemas.wtf-p.dev/project/state/v1",
  "type": "object",
  "additionalProperties": false,
  "required": [
    "schema",
    "project_id",
    "revision",
    "phase",
    "status",
    "current_section_uri",
    "progress",
    "active_checkpoint_uris",
    "updated_at"
  ],
  "properties": {
    "schema": { "const": "wtfp.project.state/v1" },
    "project_id": { "$ref": "https://schemas.wtf-p.dev/project/common/v1#/$defs/identifier" },
    "revision": { "type": "integer", "minimum": 0 },
    "phase": {
      "enum": ["initialized", "mapped", "outlining", "planning", "writing", "reviewing", "ready", "delivered"]
    },
    "status": { "enum": ["active", "paused", "blocked", "complete"] },
    "current_section_uri": {
      "type": ["string", "null"],
      "pattern": "^project://sections/[A-Za-z0-9._~-]+$"
    },
    "progress": {
      "type": "object",
      "additionalProperties": false,
      "required": ["sections_total", "sections_complete", "word_target", "word_count"],
      "properties": {
        "sections_total": { "type": "integer", "minimum": 0 },
        "sections_complete": { "type": "integer", "minimum": 0 },
        "word_target": { "type": "integer", "minimum": 0 },
        "word_count": { "type": "integer", "minimum": 0 }
      }
    },
    "active_checkpoint_uris": {
      "type": "array",
      "items": { "type": "string", "pattern": "^project://checkpoints/[A-Za-z0-9._~-]+$" },
      "uniqueItems": true
    },
    "last_transition": {
      "type": "object",
      "additionalProperties": false,
      "required": ["from", "to", "reason", "at"],
      "properties": {
        "from": { "type": "string", "minLength": 1 },
        "to": { "type": "string", "minLength": 1 },
        "reason": { "type": "string", "minLength": 1 },
        "at": { "$ref": "https://schemas.wtf-p.dev/project/common/v1#/$defs/timestamp" }
      }
    },
    "updated_at": { "$ref": "https://schemas.wtf-p.dev/project/common/v1#/$defs/timestamp" }
  }
}