How to Build a Unified Social Media Inbox via API

One schema, four platforms

The Direct Messages API normalizes Facebook Messenger, Instagram, Telegram, and Bluesky into two resources:

• Chat — a conversation with one participant: participant_name, participant_avatar_url, last_message_at, platform-specific metadata.
• Message — direction (inbound/outbound), body, attachments, status, timestamps.

Your inbox renders these two objects. The platform differences — Meta webhooks vs Telegram Bot API vs AT Protocol polling — stay on Postproxy’s side of the line.

The conversation list

Pull chats per connected profile, ordered by latest activity:

curl "https://api.postproxy.dev/api/profiles/PROFILE_ID/chats?per_page=20" \
  -H "Authorization: Bearer YOUR_API_KEY"

Merge the lists from all profiles, sort by last_message_at, and that’s the left pane. Each chat already has the participant’s display name and a stable avatar URL — no platform lookups to render a row. before / after timestamp filters handle incremental refresh.

The thread view

curl "https://api.postproxy.dev/api/chats/CHAT_ID/messages?per_page=50" \
  -H "Authorization: Bearer YOUR_API_KEY"

Messages come newest-first with everything a thread UI needs:

• direction decides bubble alignment.
• attachments carry stable storage URLs — inbound media is mirrored off platform CDNs, so images don’t break when Meta’s tokens expire.
• external_read_at / external_delivered_at give read receipts (Facebook and Instagram).
• reactions is the live reaction state per message.
• external_edited_at and external_deleted_at let you render “edited” and tombstones.

Real-time updates

Subscribe one webhook endpoint to the message events and fan out to your UI over your own websocket/SSE:

• message.received — new inbound message (the event that bumps a chat to the top)
• message.sent, message.delivered, message.read — outbound lifecycle
• message.edited, message.deleted — thread mutations
• reaction.received — reactions, including removals

One caveat: Bluesky has no webhooks upstream, so inbound Bluesky messages arrive via a ~5-minute poller. The message.received event still fires — just with up to 5 minutes of latency.

Replying

Same send call regardless of platform:

curl -X POST "https://api.postproxy.dev/api/chats/CHAT_ID/messages" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{ "body": "On it — refund issued, you should see it in 3-5 days." }'

Track the returned message’s status (pending → published, or failed with error_details) to show send state in the composer, or let message.sent / message.failed webhooks drive it.

Capability differences to surface in the UI

The schema is uniform; platform abilities aren’t. Disable composer features per chat’s platform:

The 24-hour rule is the one to design around: when a Meta chat’s last_inbound_at is older than 24 hours, grey out the composer — the send would fail anyway. (Private replies are the comment-triggered exception.)

Beyond DMs

The same inbox pattern extends to public interactions: comments on Instagram, Facebook, and Threads, and Google Business reviews — all webhook-driven, all replied to with one POST. Per-platform send guides: Instagram DMs, Facebook Messenger.