Creating Bluesky starter packs from code: three AT Protocol records and one non-idempotency trap
Bluesky starter packs look like a single thing in the app — a shareable page that lets a new user follow a curated group in one tap. At the protocol level they are three separate records glued together by references, and if you create them from code (we do, as part of an automated outreach pipeline), the decomposition matters: it decides what you can update later, what you can only create once, and where a naive script will quietly make a mess. The three records Everything below is plain com.atproto.repo.createRecord / putRecord calls against your own PDS — no special API surface. 1. The list — app.bsky.graph.list . A starter pack is backed by an ordinary Bluesky list with purpose: app.bsky.graph.defs#referencelist . The list record itself holds metadata — name, purpose, createdAt, plus optional description and avatar. Members live elsewhere. 2. The memberships — app.bsky.graph.listitem . One record per member, each holding the member's DID and the list's AT-URI. There is no "add 20 members" batch call in the record layer: twenty members means twenty listitem creates. Plan for partial failure in the middle of that loop — more below. 3. The pack — app.bsky.graph.starterpack . The record that makes the share page exist. Per the lexicon, name , list , and createdAt are required; list is the AT-URI of the referencelist from step 1, the name is capped at 50 graphemes, and optional feeds can attach custom feeds. The official limits: up to 150 people, up to 3 feeds. The share URL is derivable, not returned: https://bsky.app/starter-pack/{your-handle}/{rkey} where {rkey} is the tail of the starterpack record's AT-URI. The trap: creation is not idempotent Every createRecord mints a fresh rkey. Run your create-starter-pack script twice and you have two packs with two URLs, both live, both indexed — and the one you already shared is not the one your script now reports. There is no natural key (like a title) that the protocol dedupes on. Our rules after learning this: Creation