ENGINEERING CASE STUDY / 03
Multiplayer Cursor.
One shared space. Explicit state synchronization, from pointer input to the remote canvas.
PROJECT SCOPESingle-process rooms. The portfolio demo is a local simulation, not a live multi-user session.
01 / CONTEXT
The problem worth solving.
Pointer movement is frequent. Network delivery is irregular. Naive broadcasting makes movement expensive and uneven.
Engineering objectives
- Synchronize current room state.
- Validate messages at runtime.
- Restore presence after disconnection.
02 / SYSTEM DESIGN
Follow the flow.
Implementation details
- The throttler sends the newest position.
- Room state tracks participants and canonical events.
- Interpolation smooths incoming samples; heartbeats and backoff manage reconnects.
03 / TRADEOFFS
The reasoning behind the code.
Ephemeral state
Keep current positions, not durable movement history.
Native WebSockets
Make protocol guarantees explicit.
Engineering challenges
Stale updates, uneven delivery, and duplicate presence need distinct recovery rules.
Security & performance boundaries
Messages have size and coordinate bounds. Resume tokens are not authentication.
04 / EVIDENCE
What’s there. What’s next.
Public source includes protocol, interpolation, and reconnect tests. Try the local illustration below or open the linked deployment.
Explore the source, documentation, and tests to inspect the implementation and its current boundaries.
Read the repository