Add h3 types to auto-imports

The Problem

When working with Nuxt server routes, developers frequently need to use h3 types like H3Event, H3Error, and EventHandler. However, IDE auto-import suggestions weren’t working for these types, creating friction in the developer experience.

The root cause was that Nitro’s auto-import configuration intentionally filters out uppercase exports using a regex pattern (!/^[A-Z]/.test(n)). While h3 is a transitive dependency of Nuxt/Nitro, TypeScript could resolve imports like import type { H3Event } from "h3", but IDEs wouldn’t offer auto-import suggestions unless developers manually added h3 as a direct project dependency.

This was particularly painful for common use cases:

// Developers had to manually import these types
import type { H3Event, EventHandler } from 'h3'

export default defineEventHandler((event: H3Event) => {
  // Handler logic
})

Adding h3 as a devDependency was a workaround, but it proved insufficient in pnpm workspaces and added unnecessary friction—requiring a direct dependency solely for editor ergonomics.

The Solution

I added explicit h3 type imports to Nitro’s imports presets configuration, bypassing the uppercase export filter. The fix distinguishes between runtime values and type-only imports:

Runtime imports (these are classes that exist at runtime):

• H3Event
• H3Error

Type-only imports (pure TypeScript types):

• EventHandler
• EventHandlerRequest
• EventHandlerResponse
• EventHandlerObject
• H3EventContext

The implementation adds a presets array to the Nitro imports configuration:

imports: {
  presets: [
    {
      from: 'h3',
      imports: ['H3Event', 'H3Error'],
    },
    {
      from: 'h3',
      imports: [
        'EventHandler',
        'EventHandlerRequest',
        'EventHandlerResponse',
        'EventHandlerObject',
        'H3EventContext',
      ],
      type: true,
    },
  ] as const,
  // ... existing autoImport and dirs config
}

During code review, CodeRabbit suggested applying as const to the entire presets array rather than individual imports for improved type inference—a suggestion I implemented in subsequent commits to follow codebase conventions.

Files Changed

Timeline