Keyhold

Keyhold is a property marketplace covering England, Wales, Scotland and Northern Ireland, for both long-stay rentals and homes for sale. Visitors search verified listings, explore them on a map with price pins, and send a single enquiry — or talk to an AI assistant that searches the real inventory, compares homes, and books a viewing without leaving the chat. It was built as a white-label product rather than a one-off site, so the whole thing rebrands from a single constants file. The interesting constraint was that nothing should require a developer after handover. That pushed almost every design decision. The colour palette is five brand values plus a radius; everything else — greys, borders, hover tints, the dark sections — derives from them in CSS with colour-mix, so a host picks five colours and the entire site moves together. Fonts are eight self-hosted families switched from the same screen. Pages are assembled from ten blocks that reuse the same components as the hand-built pages, so builder output never looks like a different site. The header, footer, hero carousel, cookie banner, privacy policy and terms are all CMS-driven, with the shipped copy as fallbacks so a fresh install renders identically to the designed version. The AI runs through OpenRouter with a hand-written tool loop rather than a framework: the assistant searches properties, drafts bookings and requests viewings against real data, and refuses to invent a listing it cannot find. Its name, manner, knowledge base and behaviour are all configured in the dashboard, and staff can upload PDFs or Word documents whose text is extracted on upload so the model has the actual wording rather than a link. Separate AI surfaces draft property copy, write blog articles, and generate the search and answer-engine copy — each one fed real site data so it has facts to work from instead of inventing them. Host-authored instructions are fenced inside the prompt with the safety rules restated afterwards, so nothing typed into the dashboard can talk the assistant out of them. I architected and built it solo: schema and migrations, the public site and its animations, the agent and its tools, the admin dashboard, the page builder, the R2 upload pipeline, and the SEO layer — canonical URLs, sitemap, robots, JSON-LD and an llms.txt brief for answer engines. Around 24,000 lines of TypeScript across seven collections, ten CMS globals and eleven dashboard sections.