Your sitemap is advertising redirects — and your canonical tag points at one

Run curl -sI over the URLs in your own sitemap. We did, and 27 of ours answered 307 Temporary Redirect — every route on the site. The canonical tag was worse: each page declared a canonical URL that redirected to the page itself. We were telling crawlers, on every single page, that the authoritative copy lives one hop away.

How a static host quietly forks every URL in two

The mechanics are mundane, which is why this survives review. A static build writes each route as route/index.html. The host serves /route/ directly — and answers the bare /route with a 307 to the slash form. So every route on the site has two URLs: one real, one a redirect. Which one your HTML advertises depends on whoever typed the link.

Our templates typed the bare form everywhere it matters most: the canonical tag, og:url, the sitemap generator, and llms.txt — the four surfaces whose entire job is to name the authoritative URL. All four advertised the redirect.

Why a self-referential redirecting canonical is worth fixing

• A canonical pointing at a redirect is a mixed signal. The tag exists to end URL ambiguity; making crawlers resolve a hop to find the 'canonical' copy reintroduces exactly the ambiguity it was meant to close.
• Sitemap URLs are supposed to be final. Search engines tolerate redirects there, but every hop is a chance for a URL to get indexed in the form you didn't pick — and split whatever authority the page earns across two spellings.
• AI crawlers fetch exactly what you wrote. llms.txt consumers and answer-engine bots are literal; an extra 307 on every fetch is latency you chose, on the surface built for machines.

The fix is a policy plus one helper, not a link hunt

Chasing individual links is the wrong altitude. The durable fix was three moves: pick the slash form as policy (trailingSlash: "always", so the build itself rejects the other spelling); route every emitted URL — canonical, og:url, sitemap, llms.txt — through one path-normalize helper in the head layout and URL generators; and re-audit with curl -sI over every sitemap URL, expecting nothing but 200s.

The one-helper rule is what made the follow-up cheap: once advertised URLs were normalized in one place, sweeping the remaining 1,100+ bare-path hrefs inside page bodies was a mechanical pass, and a link check in the build now fails on any regression. (nlqdb is the database you talk to; this is one of the engineering notes from building it in the open.)

The general lesson: every surface that names a URL — canonical, og:url, sitemap, llms.txt, internal hrefs — should call the same normalize function. If two of them can disagree about your own address, they eventually will, and you'll advertise the disagreement to every crawler that visits.