Add a comment. Attach files first via request_upload → PUT → attach_file.

Body: markdown. Optional colour (D137, use sparingly; markdown stays the main format): <mark>text</mark> highlights (yellow; or <mark data-color="green">), <span data-color="red">text</span> colours text; colours yellow, green, red, blue, purple (e.g. green = passed / expected, red = bug / actual, purple = question); any other HTML is shown as plain text; keep the open and close tag in the same paragraph. A new comment needs no version. To attach files, upload first (request_upload → PUT → attach_file) and pass the returned paths in attachments. To SHOW an image (screenshot) inline, also write ![file name](path) in the body where it belongs — BoardMark renders it as a picture and drops its chip; never paste base64 / data: URLs (they are not shown). To REPLY to a comment, pass its seq (from list_comments) as reply_to; omit it (or null) for a new top-level comment. Replying to a reply is fine: the server files it under that thread's top-level comment (returned frontmatter.reply_to) while frontmatter.in_reply_to keeps the comment you answered. A seq that does not exist on this issue → 400 validation_failed (field reply_to). The author of the comment you answer is notified by email. To mention someone (they get an email), write [@Their Name](mention:usr_…) with their user id and name from list_people (the reporter: the issue's reporter); only people who can open the project are notified. Commenting makes you (the token's user) a watcher of the issue.

You act with exactly the rights of the user who owns this token; a project you cannot see returns not_found.