# Link a GitHub Issue + Linear Ticket on a PR

Appends a Sentry-style `#### Issues` block to a PR description, referencing both the GitHub issue and the Linear ticket pulled from the issue's `linear-linkback` comment.

## Inputs

- `<issue-url>` — GitHub issue URL like `https://github.com/<owner>/<repo>/issues/<n>`. Issue number alone is fine if the PR is in the same repo.
- (optional) `<pr-number>` — defaults to the open PR for the current branch.

## Steps

1. **Resolve the PR number** — skip if user supplied one:

   ```bash
   gh pr view --json number,body -q '.number'
   ```

   If no PR exists on the branch, stop and tell the user.

2. Extract issue number + repo from the input URL, or accept a bare `#1234` for current repo.

3. Fetch the Linear ticket from the issue's linear-linkback comment:

   ```bash
   gh issue view <n> --repo <owner>/<repo> --json comments \
     -q '.comments[] | select(.author.login=="linear-code") | .body' \
     | grep -Eioe '[a-z]+-[0-9]+' | head -1
   ```

   If no match, fall back to asking the user for the Linear key, or omit it.

4. Read the existing PR body so you can append rather than overwrite:

   ```bash
   gh pr view <pr-number> --json body -q '.body'
   ```

5. Construct the new body. If the body is empty, use just the `#### Issues` block. Otherwise, append it after a blank line. Don't duplicate — if `#### Issues` is already present, replace that section instead of adding a second one.

   Format:

   ```markdown
   #### Issues

   * Resolves: #<n>
   * Resolves: <linear-key>
   ```

6. Update the PR with a heredoc to preserve newlines:

   ```bash
   gh pr edit <pr-number> --body "$(cat <<'EOF'
   <new body>
   EOF
   )"
   ```

7. Confirm by echoing the resulting PR URL:

   ```bash
   gh pr view <pr-number> --json url -q '.url'
   ```

## Notes

- Linear linkback comments are posted by the GitHub user `linear-code`. The body contains a markdown link whose text is the Linear key, e.g. `PY-2357`.
- Project keys vary per repo (`PY-…` for sentry-python, `JS-…` for sentry-javascript, etc.) — the regex `[a-z]+-[0-9]+` covers them.
- Don't strip existing PR content. Always read first, append/replace second.
- If the issue doesn't have a Linear linkback yet (newly filed), proceed with just the GitHub issue reference and tell the user the Linear key is missing.