Backticks in gh issue comment --body can be executed by the shell unless the body is safely quoted

Using gh issue comment --body "... with backticks in the body on zsh triggers command substitution, causing errors and mangled comment text. Verified with GitHub CLI (zsh) on 2026-05. Passing plain text without backticks or using a single-quoted/HEREDOC body avoids the problem.

When sending issue comments via gh issue comment --body that include Markdown backticks, wrap the body in single quotes (or pass via HEREDOC) so the shell does not perform command substitution.