Next.js — engineering articles by Suman Debnath

A nighttime desk illuminated by a warm lamp, featuring a laptop displaying terminal windows routing Markdown requests via HTTP headers, with handwritten technical notes propped beside it.

19 October 2026·7 min read

Two Next.js rewrites that serve Markdown to agents without breaking the cache

Serve Markdown for Accept: text/markdown in Next.js by placing a beforeFiles rewrite on static pages and a fallback rewrite on unmatched paths in next.config.ts, pointing at force-static route handlers that send Vary: Accept. Unlike proxy.ts or headers() in page.tsx, the HTML cache key and Next's router Vary header stay untouched.

Next.js
Routing
AEO

A printed page held up to the light, with one central block entirely blank where content should be.

26 August 2026·6 min read

Why is my JSON-LD missing from the HTML in Next.js?

Next.js does not emit a script element for a component using next/script with strategy beforeInteractive. It serialises the payload into a self.__next_s array that the client bundle reads after hydration, so JSON-LD declared that way is absent from the served HTML and invisible to any crawler that does not execute JavaScript.

Next.js
Structured Data
AEO
Debugging

A signpost with the old nameplate unscrewed and leaning against the post as a new one is fixed on.

24 August 2026·5 min read

Next.js 16 replaced middleware.ts with proxy.ts

In Next.js 16, middleware.ts is gone. The replacement is proxy.ts at the project root, exporting a function named proxy(request) and a config.matcher, and it runs on the Node runtime rather than Edge. The matcher is read statically at build time, so it cannot reference an imported constant.

Next.js
Migration
Routing

Two Next.js rewrites that serve Markdown to agents without breaking the cache

Why is my JSON-LD missing from the HTML in Next.js?

Next.js 16 replaced middleware.ts with proxy.ts

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