Super Secret Chat

#Why I built this

I’d built a lot of features that used real-time without actually implementing the websocket side myself. Pusher, Firebase, Supabase Realtime. They all hide the lifecycle, the room model, the broadcast logic.

This was the smallest project I could come up with that exercises all of that without becoming a Slack clone.

#What it does

• Rooms. Users join a named room and only see messages from that room.
• Edit and delete on messages. When someone edits, everyone in the room sees the change and a small “edited” marker.
• Presence notifications when someone joins, leaves, or edits.
• docker-compose up --build runs the same setup the production deploy uses.

#Architecture

There’s one Express + Socket.io process acting as the gateway. State lives in memory. The room registry and the message log are JavaScript objects, not a database. When a client reconnects, the gateway re-emits the current room state so they catch up.

#Technical decisions

Socket.io over a raw WebSocket. Reconnection, room semantics, and event-based dispatch are all built in. A raw ws server would have been a couple hundred lines of plumbing for the same thing.

In-memory state. The first version doesn’t need durability. When the server restarts, room history clears. Fine for a prototype.

Docker first. docker-compose up --build is the only way I run it. There’s no separate “for prod” config.

Mutations are broadcast as patches. Edits and deletes send a patch instead of a replacement. Everyone sees the same view of history including the edited marker.

#What I learned

Socket rooms aren’t really a primitive. They’re a convention built on top of namespaced emit calls. Knowing that early made the room registry a five-line map instead of something more complicated.

Reconnection is what reveals weak invariants. If a client drops mid-edit, every assumption you made about ordering shows up.

“Edits broadcast to everyone” is a product decision, not a technical one. Worth saying that out loud somewhere.

#Next steps

• Persist rooms and messages to Postgres, or SQLite plus Litestream for the small case. So history survives a restart.
• Authentication via passkey or magic link. Right now anyone with the URL can join any room.
• Optional E2E encryption for room contents. Signal-style ratchet, with the gateway as a blind relay.
• Pull the realtime client into a small npm package. The reconnection and snapshot replay logic is reusable.

Source: github.com/uzairali19/super-secret-chat-app.