{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "$id": "https://wendkeep.dev/schema/task-contract-v1.schema.json",
  "title": "WendKeep Task Contract v1",
  "type": "object",
  "additionalProperties": false,
  "required": [
    "schema_version", "contract_id", "task_id", "change_slug", "title", "phase", "status",
    "inputs", "expected_outputs", "acceptance_criteria", "requirement_ids",
    "required_sensors", "required_artifacts", "dependencies", "owner", "work_session_id",
    "evidence_envelope_id", "checked", "authored_sha256", "binding"
  ],
  "properties": {
    "schema_version": { "const": 1 },
    "contract_id": { "type": "string", "pattern": "^[a-f0-9]{64}$" },
    "task_id": { "type": "string", "minLength": 1 },
    "change_slug": { "type": "string", "pattern": "^[A-Za-z0-9][A-Za-z0-9._-]*$" },
    "title": { "type": "string" },
    "phase": { "enum": ["execute", "verify"] },
    "status": { "enum": ["ready", "blocked", "pending-evaluation", "completed", "stale"] },
    "inputs": { "$ref": "#/$defs/stringArray" },
    "expected_outputs": { "$ref": "#/$defs/stringArray" },
    "acceptance_criteria": { "$ref": "#/$defs/stringArray" },
    "requirement_ids": { "$ref": "#/$defs/stringArray" },
    "required_sensors": { "$ref": "#/$defs/stringArray" },
    "required_artifacts": { "$ref": "#/$defs/stringArray" },
    "dependencies": { "$ref": "#/$defs/stringArray" },
    "owner": { "type": ["string", "null"] },
    "work_session_id": { "type": ["string", "null"] },
    "evidence_envelope_id": { "type": ["string", "null"] },
    "tdd_required": { "type": "boolean" },
    "tdd_attestation_id": { "type": ["string", "null"] },
    "checked": { "type": "boolean" },
    "authored_sha256": { "type": "string", "pattern": "^[a-f0-9]{64}$" },
    "binding": {
      "type": "object",
      "additionalProperties": false,
      "required": [
        "project_id", "active_context_id", "head_sha", "tasks_sha256",
        "effective_spec_sha256", "artifact_manifest_sha256"
      ],
      "properties": {
        "project_id": { "type": "string", "minLength": 1 },
        "active_context_id": { "type": "string", "minLength": 1 },
        "head_sha": { "type": "string", "minLength": 1 },
        "tasks_sha256": { "type": "string", "minLength": 1 },
        "effective_spec_sha256": { "type": "string", "minLength": 1 },
        "artifact_manifest_sha256": { "type": "string", "minLength": 1 }
      }
    }
  },
  "$defs": {
    "stringArray": {
      "type": "array",
      "items": { "type": "string" },
      "uniqueItems": true
    }
  }
}