Investigate CI Failure Skill

A read-only first pass over a CI failure: turn a single URL into a per-test verdict (flaky vs real) plus a root-cause hypothesis, with no copy-paste and no manual wget.

Arguments

• $0 (required): one of
  • a GitHub PR URL (https://github.com/ClickHouse/ClickHouse/pull/NNNNN),
  • a direct S3/CI report URL (https://s3.amazonaws.com/.../json.html?PR=...&sha=...), or
  • a GitHub issue URL (https://github.com/ClickHouse/ClickHouse/issues/NNNNN) — typically a bot-generated flaky test issue. Resolved to its report URL in step 0.
• $1 (optional): master-history window in days for the flaky-vs-real verdict. Default 14.

Hard rules