A CDN country header served Googlebot $14.99 on a page declaring GBP in its structured data

The branch is four lines. `getDisplayCurrency` awaits `headers()`, tests the user agent, and returns `BASE_CURRENCY` when it matches; everything else falls through to `currencyForCountry(headerList.get('x-vercel-ip-country'))` ^[5]. BASE_CURRENCY is GBP, which the author says is the currency the subscription is genuinely priced in and the one the structured data declares ^[6]. A crawler reads the same figure from any datacentre.

Where it breaks is the test itself. `isBotUserAgent` returns false when the user agent is null or undefined ^[7], so a client that sends no user agent takes the geo path and gets whatever country its exit IP resolves to ^[18].

One failure direction costs more than the other. A false match shows a human in Frankfurt the GBP price, and the author already describes the localised figure as an approximation ^[15]. A miss restores the original defect, where the rendered price comes from the datacentre's country and disagrees with the GBP in the `Product` markup ^[3][19]. Over-matching is the cheap error. A pattern that fires on any user agent containing the letters "bot" is defensible here ^[7].

The author writes: "The structured data mismatch is not really a crawler problem, it is a duplication problem." ^[11] The page component resolves the currency once and hands it to the JSON-LD graph, the rendered pricing section and `faqs(currency)` ^[12]. That last call matters. The FAQ contains the sentence "£10 a month for unlimited scanning", and that sentence is also emitted as `FAQPage` structured data ^[13].

The detector sits in its own module because two callers need the identical answer, the currency resolver and the edge proxy ^[10]. "Two regexes that are supposed to agree will eventually disagree," the author writes ^[10].

What could cost the most here is documented the least. According to the post, a price in structured data that does not match the price on the page is a documented reason for rich results to be suppressed, and in worse cases a manual action instead of a silent demotion ^[4]. The post does not cite that documentation or report any action taken against the site ^[21]. What it does report is the observed bug it opens with: Googlebot indexing a business that charges in pounds as an American product at an American price ^[2].

You can check the fix from outside. On the published page, a curl with a bot user agent returns the same thing every time, while a VPN to Germany or Japan changes what a browser shows ^[16].