threads.text.max_graphemes - letmepost.dev

What it checks

countGraphemes(text) <= 500 regardless of post shape (text-only, image, video, carousel).

Why 500

Meta’s published Threads API documents the 500-character cap. We use grapheme-aware counting so a single emoji counts as 1, matching Meta’s own behavior on /threads create-container calls.

Failure response

{
  "error": {
    "code": "preflight_failed",
    "rule": "threads.text.max_graphemes",
    "platform": "threads",
    "message": "Post text is 612 graphemes; Threads allows at most 500."
  }
}

Remediation

Trim the post. Use the same grapheme-aware approach as for Bluesky — see bluesky.text.max_graphemes for code.