OpenTelemetry in Next.js works, but the default propagator silently breaks the trace at the edge/node boundary. Here's what you need to configure explicitly so context doesn't vanish between Middleware, Server Components, and Server Actions.
Zod sells itself as "define once, validate everywhere." In Next.js 16 with Server Actions, edge middleware, and API routes, that's only partially true. Three concrete failure modes and the pattern that prevents them.
Web Crypto API looks like one thing — until you try to reuse the same encryption code across browser, Node.js, and Next.js edge runtime. The differences are subtle, they're documented, and almost nobody reads the docs until something blows up.
I tested 4 authorization patterns in Next.js 16 Middleware with edge runtime. One causes silent race conditions, another gives you unexpected latency, and only one scales without compromises. Here's the honest tradeoff analysis of each.
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