Bonfire Focus
A collaborative Pomodoro app for studying together in real time.
Overview
A realtime collaborative Pomodoro timer: join a room, and everyone sees the same countdown, the same ambient sound, and the same streak, synced to the second, with no visible server round-trip.
Why I built it
Solo focus timers are easy; a focus timer several people trust enough to actually sit through together is a distributed-systems problem wearing a UI. Wanted to see how far a naive shared timer could be pushed toward "feels instant and never drifts."
Architecture
Next.js 14 on Vercel, Supabase Realtime for presence and state sync, PostgreSQL for room/session/streak data, a custom Three.js + GLSL rendering pipeline for the ambient particle visualization, and the Web Audio API for all sound, so no audio files ship with the app.
Challenges
A naive shared timer that decrements a counter on each tick drifts visibly once a client's main thread stalls. Instead, each write stores time_left alongside an updated_at timestamp; any client joining mid-session (or recovering from jank) derives the exact current second from the wall-clock delta against that timestamp, not from counting ticks, covered by unit tests for the running/paused/idle/finished state transitions. Ambient audio is synthesized procedurally (Brownian motion plus Paul Kellett's pink-noise algorithm) rather than shipped as files. Stats ingestion is protected by a SECURITY DEFINER Postgres function enforcing server-side validation and row-level locking, so concurrent writes can't corrupt a streak.
Outcome
Live and used for real study sessions. 3 stars on GitHub, 32 merged PRs of iterative feature work: solo mode, guest UX, room privacy, PWA support, and a full settings/theming pass.