Support lazy-loading to keep the initial client bundle small (@sentry/nuxt)

[felixgabler]

Problem Statement

The legacy Nuxt 2 module @nuxtjs/sentry exposed a [lazy: true option](https://sentry.nuxtjs.org/guide/lazy-loading/) that:

• removed the Sentry runtime from the default client bundle
• injected a mocked $sentry instance together with $sentryReady() / $sentryLoad() helpers so we could load Sentry on-demand (e.g. after user consent or on the first error)

In production this shaved 40 kB (gzipped) off the initial JS sent to every visitor, important for Core Web Vitals on mobile connections.

The current Nuxt 3 integration always ships the full SDK in the main bundle. For apps that need the SDK only after explicit user consent or once the user is authenticated this is avoidable overhead.

Solution Brainstorm

It would be great if @sentry/nuxt could bring back first-class lazy-loading support, for example:

1. Config flag

   // nuxt.config.ts
   sentry: { lazy: true, /* … */ }

2. Mocked API injection (parity with Nuxt 2)

   • Inject a lightweight proxy that queues calls until the real SDK is loaded.
   • Expose $sentryReady() (Promise) and optionally $sentryLoad() to manually trigger the load.

3. Route-level auto-loading
   Allow opting into SDK loading per-route via route rules or middleware so that public/landing pages remain lean.

4. Vite split-chunk
   Generate a separate sentry.client.js chunk and load it dynamically so source-maps & release artifacts continue to work as today.

[mydea]

Hey, thanks for writing in.
This is generally an understandable ask, however sadly lazy-loading of the SDK is pretty complicated with all the functionality the SDK offers today. As of now, the best way to achieve lazy loading is to simply use the browser SDK Loader script: https://docs.sentry.io/platforms/javascript/install/loader/

This is obviously not the same as using the Nuxt SDK, but the Nuxt SDK does a lot of other things as of now that would have to be considered very carefully for lazy loading. I'll put this into the backlog, as the team is very busy right now, but at some point we do want to revisit the topic of lazy loading of the SDK (not just the nuxt sdk) generally - but I can't give an estimate on when we'll get around to doing this!