A marketplace that recruits whichever side of itself is short

The first version was generated on an AI app builder. Before any code moved, a written audit compared what the export contained with what the business needed. The schemas, backend functions and payment logic were then ported and rebuilt on Supabase, Stripe and Vercel in stages, and the builder's SDK was removed completely. The migration was done with Claude Code and reviewed as pull requests.

With no server of its own, the browser talks to Postgres directly, so row-level security is the whole authorisation layer. Policies, function exposure and storage rules live in ordered migrations, with SQL tests for the rules that matter (listing privacy, enquiry limits, blocking, account deletion), browser tests, and CI for accessibility, layout stability, security, uptime and backups.

Signed out, the site is a shop window: home page, seller and buyer pages, pricing, how it works, project closeouts, support, and sixteen material category pages. Signed in, it is a tool (find material, answer an enquiry, list the next pallet) across a five-destination tab bar with an account menu for listings, saved listings, alerts, payment history and the business profile. Both run from the same codebase, and the browse surface is the one page that has to be both at once: public enough for a stranger, and the product for someone with an account.

Which side is short changes week to week, so the home page counts live supply against a threshold constant and argues accordingly: recruiting sellers while listings are thin, buyers once they are not. Nothing is fabricated to fill the gap. When there is no true number to show, the proof strip shows nothing at all rather than a placeholder count.

Revealing a seller's phone number is a server-side action, not a field hidden with CSS. The number is not in the page source before it is revealed, so reading the HTML does not get you it. Enquiry limits are counted per buyer-seller pair, so the platform cannot be used to message every seller on it. Business verification and reporting sit alongside. Demo listings admit what they are: they replace the contact form with an alert signup instead of pretending a seller will reply.

Pricing plans live in a pricing_plans table, read by the pricing page and by the checkout. A content test fails the build if a price is typed into page copy anywhere on the site. Marketing copy therefore cannot drift from what a customer is actually charged, not because someone remembers to update both, but because forgetting stops the build.

Route heads are prerendered per route, so a crawler sees them without running JavaScript, with a sitemap and FAQ structured data alongside. The sixteen material pages exist to be landed on: someone searching for a specific material arrives at a page about that material, rather than at a home page competing for every term at once.