How to syndicate to Bluesky (POSSE)

Status: shipped. The bluesky driver, colophon syndicate, and the ledger work today.

POSSE = Publish on your Own Site, Syndicate Elsewhere: the post is canonical on your blog, and a copy is cross-posted to Bluesky linking back to it.

Steps

Have a Bluesky account — note your handle (e.g. me.bsky.social).
Create an app password: Settings → Privacy and security → App passwords → Add (don't use your main password). Copy it.
Export it as a CI secret: export BLUESKY_APP_PASSWORD=...

Configure a syndicator (driver: bluesky):

sites:
  - id: main
    federation:
      syndication:
        - id: bluesky
          driver: bluesky
          handle: me.bsky.social
          app_password: "{env:BLUESKY_APP_PASSWORD}"   # never a literal
environments:
  - name: production
    syndicate: [bluesky]      # only this env cross-posts; preview/draft never do

Publish, then syndicate:
```
colophon publish  --env production --allow-publish
colophon syndicate --env production --allow-publish
```
colophon authenticates (handle + app password → AT-proto session), creates the post (with a link card back to the canonical), records the Bluesky URL in the ledger, and renders it as an "Also posted on…" (u-syndication) link. Idempotent via the ledger.

Notes

Bluesky's limit is 300 characters — long posts are truncated with a link back; set syndicate_text: per post for a custom blurb.
Commit the syndication ledger (.colophon/syndication.json); without it a fresh runner would re-post, so syndicate refuses to run blind.
Replies/likes/reposts on the Bluesky copy can flow back to your post via Bridgy backfeed — see Show webmentions.
Prefer not to manage credentials? Use driver: bridgy with network: bluesky.

Generated from docs/howto/syndicate-bluesky.md — edit it there.