Plumbline Property Advisory, Budapest

Plumbline turns “can you check this flat before I sign on Friday?” into a booked, access-checked visit in two minutes, so a solo building engineer in Budapest stops losing buyers while she's up in an attic.

The business (fictional, modelled on a real Budapest practice): Réka checks flats and houses before people buy them (55,000 HUF for a flat, 75,000 HUF for a house, travel fee outside the city). Her quirks: every buyer has a hard deadline, the day they sign the deposit; 1 visit in 6 fails because nobody opens the door; and messages arrive at midnight in German, English and Hungarian while she's on site.

What I built:

→ Deadline-aware booking: only times before the deposit date, travel zone and fee from the district, route-friendly slots

→ Private links for the buyer and the listing agent: the agent confirms access with one tap. If they don't, the buyer and Réka are warned 24 h ahead, not on the doorstep

→ AI inbox: paste a WhatsApp in any language and get the address, deadline and language extracted, 3 free times and a drafted reply. Times and prices come from tested code, never from the AI

→ The buyer's own note becomes an AI site brief for Réka

→ Owner view: today's route, the one thing that needs her, time saved this week

→ English · German · Hungarian everywhere, real email notifications, and a demo clock ("time travel") to watch reminders and alerts happen

Before → after: ~2 days → ~2 min to confirm · ~25 min → ~0 admin per booking · locked doors caught a day early

Try it, no sign-up, with a 12-step tour: https://plumbline-property-advisory.lovable.app

Built in 5 days with Lovable + Claude Code · 113 unit tests · process video attached.

Social post: https://contra.com/community/nOqLE0g7-multilingual-booking-app-for-budapest-property