perf(nuxt)!: remove legacy app context

[danielroe]

🔗 Linked issue

resolves nuxt/nuxt#14002

❓ Type of change

• 📖 Documentation (updates to the documentation or readme)
• 🐞 Bug fix (a non-breaking change that fixes an issue)
• 👌 Enhancement (improving an existing functionality like performance)
• ✨ New feature (a non-breaking change that adds functionality)
• ⚠️ Breaking change (fix or feature that would cause existing functionality to change)

📚 Description

We are currently including a legacy plugin that creates a proxy converting the Nuxt 3 app interface to a Nuxt 2 compatible context. This is probably not needed in majority of new apps, but it is still included in bundle.

This PR completely removes the legacy context feature.

👉 Migration

If you are using plugins (perhaps injected by a module) that are relying on the Nuxt 2 format of (context, inject) => void then it needs to be updated to the new Nuxt 3 format of (nuxtApp) => void: https://v3.nuxtjs.org/guide/directory-structure/plugins#creating-plugins

Moreover, if you are relying on the globally available legacy-format window.$nuxt you will need to inject it yourself.

📝 Checklist

• I have linked an issue or discussion.
• I have updated the documentation accordingly.

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[pi0]

Do you have a benchmark of prod bundle size impact and percentage savings? It is considerably large, I see no reason to even keep backward-compatible code into the final release.

[danielroe]

This PR will mean by default this plugin is not included in the bundle. The impact was ~4/92 kB of uncompressed JS (saving approx 4%). Worth mentioning that previously because the components plugin was not wrapped in defineNuxtPlugin, by default the legacy app plugin was always running.

[pi0]

Then let's remove it as soon as possible to avoid misleading behavior. 4.5Kb is considerable (although gzip is probably much less in entry bundle). I initially added it for vue devtool and with intention of supporting Nuxt 2 compatible modules injecting a plugin but today it seems we need to migrate them anyway. It wouldn't worth to continue experimenting...

[danielroe]

Sounds good to me! Will update 👍

[danielroe]

Note to self: an example of a plugin that does require this is https://github.com/moritzsternemann/vue-plausible/blob/main/src/nuxt-plugin.ts.