Auto-thread on overflow

How Unison splits long drafts into a clean native thread on X, Threads, Bluesky and Mastodon.

Updated May 12, 2026·1 min read

Some networks limit posts to a few hundred characters. Auto-thread takes a draft that goes over the limit and turns it into a clean, native thread without you having to count characters or insert numbering.

Auto-thread runs on:

  • X (280 characters per post)
  • Threads (500 characters per post)
  • Bluesky (300 characters per post)
  • Mastodon (instance-dependent, typically 500 characters per toot)

Other networks (LinkedIn, Facebook, Instagram captions, Telegram, Pinterest, YouTube) have higher limits and do not need to thread, so auto-thread does not run there.

How it splits

Auto-thread breaks at the nearest sentence boundary, then word boundary, then character boundary, in that order. It avoids splitting URLs and mentions across two posts. Numbering (1/, 2/, 3/) is added at the end of each segment by default, but you can disable it from Settings → Composer.

Editing each segment

Once the draft is split, every segment is editable. Switch to the auto-thread preview tab in the composer and click any segment to tweak it before publishing. Edits there only affect that segment for that channel.

Disabling auto-thread per draft

Open the draft, switch to the channel where you want to opt out, and toggle Auto-thread off in the meta strip. The post will fail to publish if it exceeds the channel limit, so you usually only do this when you have written a long draft on purpose for a network that handles it.

Tips

  • The cleanest threads have one idea per segment. Write the body, then glance at the auto-split to see if any segment cuts off mid-thought; if it does, rephrase the original sentence.
  • Auto-thread numbers can be replaced with custom prefixes (eg Hot take 1·) under Settings → Composer → Thread numbering.

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