How Postproxy publishes to Bluesky
Bluesky's publishing model
Bluesky runs on the AT Protocol — a federated network where every action is a typed record (a lexicon) written to your data repo. Posting means uploading any media as blobs, then creating an app.bsky.feed.post record with text plus optional embeds. Postproxy handles the session, blob uploads, facet extraction, and record creation — you send a normal post body and we translate it into the right XRPC calls.
Mentions, hashtags, and links
Bluesky doesn't auto-linkify plain text — it expects pre-computed facets that mark byte ranges in your post as mentions, tags, or links. Postproxy extracts @handle, #tag, and URL patterns from your post body and resolves handles via the directory, so the same plain-text body you send to X works on Bluesky without extra markup.
Link cards and image embeds
When a post contains at least one URL and no media attachments, Postproxy fetches the Open Graph metadata, downloads the OG image (skipping anything past Bluesky's ~1 MB blob limit), and uploads it as an app.bsky.embed.external link card. If your post has any image or video attachments, those win at the embed level and the URL stays a clickable facet link — Bluesky doesn't allow both.
App passwords, not real passwords
Bluesky's main account password won't work for API posting when 2FA is enabled — and even when it does work, the API will warn you off. Always issue an app password at bsky.app/settings/app-passwords. Postproxy stores the app password, keeps the session token refreshed, and surfaces a clear reconnect prompt if the user ever revokes it.
