Route files’ type imports don’t work when imported via JSDoc `@import`

Describe the bug

In a project that uses JavaScript with JSDoc type annotations, the following works:

/** @type {import('./$types.d.ts').PageServerLoad} */
export async function load({ params }) {

But if you want to put the import at the top of the file with all your other imports, using JSDoc @import:

/** @import { PageServerLoad } from './$types.d.ts' */

/** @type {PageServerLoad} */
export async function load({ params }) {

You get a type error:

The return type of an async function or method must be the global Promise<T> type. ts(1065)
index.d.ts(1512, 63): The return type of an async function or method must be the global Promise<T> type. Did you mean to write Promise<OutputData>?

Reproduction

https://stackblitz.com/edit/sveltejs-kit-template-default-sbdxvh1e?file=README.md

To reproduce, run npm run check.

See how routes/+page.js errors but routes/about/+page.js does not.

Logs

System Info

System:
    OS: macOS 15.6.1
    CPU: (16) arm64 Apple M4 Max
    Memory: 640.02 MB / 64.00 GB
    Shell: 5.9 - /usr/local/bin/zsh
  Binaries:
    Node: 24.9.0 - /usr/local/bin/node
    Yarn: 1.22.22 - /opt/homebrew/bin/yarn
    npm: 11.6.0 - /usr/local/bin/npm
  Browsers:
    Chrome: 141.0.7390.54
    Chrome Canary: 143.0.7454.0
    Edge: 141.0.3537.57
    Firefox: 140.0.2
    Firefox Developer Edition: 141.0
    Safari: 18.6
  npmPackages:
    @sveltejs/adapter-node: ^5.3.1 => 5.3.1 
    @sveltejs/kit: ^2.37.0 => 2.37.0 
    @sveltejs/svelte-json-tree: ^2.2.1 => 2.2.1 
    @sveltejs/vite-plugin-svelte: ^6.1.3 => 6.1.3 
    svelte: ^5.16.0 => 5.38.2 
    vite: ^7.1.3 => 7.1.9

Severity

annoyance

Additional Information

No response

Start with the StackBlitz reproduction and compare routes/+page.js with routes/about/+page.js, where the two JSDoc import forms behave differently. Run npm run check while tracing the route type handling; done means the top-level JSDoc @import form type-checks without the reported Promise error.