A self-cleaning Product Hunt teaser banner in Blazor WASM — 100 lines, auto-hides after launch, GA4-tracked

I'm launching SmartTaxCalc.in on Product Hunt on Tuesday, 14 July 2026 . It's a 38-tool Blazor WebAssembly tax + finance calculator I've written about here before ( the SEO/schema saga , and dropping mobile LCP from 6-8s to under 2s ). The Product Hunt launch algorithm heavily rewards products that arrive with a real coming-soon follower base — day-of upvotes correlate strongly with pre-launch "Notify me" clicks. My PH page started with 1 follower . I had 9 days to get to 50+. The obvious answer: post on LinkedIn, ask friends, DM your network. All of that has ceilings (you can only ask a favor once). The non-obvious answer that has no ceiling: convert your own organic search traffic into PH followers automatically. This is the ~100 lines of Blazor code that does that, plus the design decisions I made along the way. It's also self-cleaning — after the launch date, the banner disappears with no manual work required. Steal the pattern for your own launch. The problem SmartTaxCalc gets modest but real organic traffic — mostly from Google Search Console impressions on tax-season queries. That traffic is the warmest possible audience for a PH launch (they already found the site, they're in the target demo). But how do you route them to a PH page without: Disrupting the tax content (they came for a tax calculator, not a marketing pitch) Cannibalizing the existing tax-season banner (which drives users to /tax-calendar/ — a real retention lever) Leaving code debt after 14 July (a dead PH banner still on the site in September) Losing the dismiss preference across page navigations (SPA reality — no page refresh) Those constraints ruled out a modal, a full-width interrupt, and a "hardcoded remove after launch" approach. The design Slim horizontal bar at the top of every page. Sits ABOVE the existing tax-season banner. PH-brand orange, different from the tax-season banner's yellow/red so both are visually distinguishable when stacked. Dismissible per-user via localStorage . Auto