Habit Tracker
Full-stack habit tracker: heatmap, progress rings, daily and weekly-target habits, Telegram bot with LLM check-ins, YooKassa subscriptions.
Description
Web app for tracking daily habits and weekly-frequency goals (N×/week). Dashboard shows today's habits and a year-long heatmap; a dedicated Progress page renders Apple-style activity rings, EWMA habit strength curves (14-day half-life), weekday distribution and per-habit sparklines. All charts are pure SVG/CSS bound to OKLCH design tokens with light/dark themes. Auth via Google / Yandex / Apple (Auth.js v5). PWA with offline mode and background sync every 5 min. Telegram WebApp with auto-auth, plus a global bot that parses free-text check-ins through Yandex Cloud LLM. Paid plan via YooKassa (recurring payments, automatic FNS receipts for self-employed, pro-rata refunds, referral bonuses). Stack: Next.js 14 (App Router, i18n RU/EN), React 19, Prisma + PostgreSQL, Tailwind with OKLCH tokens, Inter Tight / JetBrains Mono. Deployed to Kubernetes via Helm + Argo CD, secrets in Vault via External Secrets, GitLab CI/CD, three K8s CronJobs for the subscription lifecycle.