◷Docházka SaaS

A seasonal visitor attraction with many part-time workers tracked attendance on paper and in chat messages. Payroll, advances and shift checklists took manual work every month, and nobody had a reliable audit trail.

• Check-in and check-out via QR code, with an ESP32 device that shows a rotating QR code on site.
• Shift checklists, manual corrections with an audit log, announcements and wage advances.
• Monthly exports for payroll; installable as a PWA on staff phones.
• SaaS fork: tenant isolation through Postgres row-level security, per-tenant onboarding, backup and restore scripts.

1. 01 DeviceESP32 firmware rendering the check-in QR code
2. 02 WebNext.js 16 + React 19, PWA
3. 03 BackendSupabase: Postgres, auth, RLS policies scoped by tenant_id in the JWT
4. 04 Data90+ SQL migrations, audit log tables
5. 05 OpsDocker, Caddy per tenant, scripted onboarding and restores

The single-tenant version grew feature by feature with agents, driven by real feedback from staff. The move to multi-tenancy was planned up front: I wrote the tenancy model and the RLS rules, then agents migrated the queries in batches while CI and tests checked that no query could cross tenants.

• ✓Single-tenant version runs in production for a client (confirmed from the production deployment copy).
• ✓SaaS fork: GitHub Actions CI, 12 test files, 94 migrations.
• ✓ESP32 QR display firmware is part of the repository.

• !The SaaS variant does not serve the original client yet; it is a parallel fork in active development.