Close an issue as a duplicate

Use this once you’ve confirmed an issue is a duplicate of another, already open (or previously filed) issue.

Steps

1. Confirm the canonical issue number first — typically the result of a prior search_similar_issues call, or manual review.

2. Call:

   close_as_duplicate {
     owner: "<owner>",
     repo: "<repo>",
     issueNumber: <n>,
     duplicateOfNumber: <canonical-issue-number>
   }

3. This performs two actions in sequence: it closes issueNumber with state_reason: "duplicate" via REST PATCH, then posts a comment on it reading Closing as a duplicate of #<duplicateOfNumber>.

4. The response includes commentUrl — the URL of the comment GitHub just created. Use it to confirm the comment posted as expected.

Notes

• This tool does not verify that duplicateOfNumber actually exists or is related — pass the number you’ve already confirmed yourself (see search-similar-issues.md).
• Closing as a duplicate does not touch the triage board’s Severity or Status fields directly; GitHub’s native “Item closed” Projects v2 workflow, if enabled on your board, handles the board-side transition (see ADR-0003).

See also

• reference/tools.md — full input/output schema.