hooks.server.ts runs unexpectedly with disabled SSR

Describe the bug

I am building an SPA and my root layout.ts contains export const ssr = false;. So far so good, +page.ts load functions now only load on the client. But I have a hooks.server.ts which is only supposed to run if +server.ts endpoints are hit. Strangely, it runs on every initial request to the page, which is weird, because with export const ssr = false; no requests should ever hit the server, at least that is what the docs suggest.

Reproduction

https://stackblitz.com/edit/sveltejs-kit-template-default-grj3wfzf?file=src%2Fhooks.server.js

Logs

System Info

System:
    OS: Linux 5.0 undefined
    CPU: (8) x64 Intel(R) Core(TM) i9-9880H CPU @ 2.30GHz
    Memory: 0 Bytes / 0 Bytes
    Shell: 1.0 - /bin/jsh
  Binaries:
    Node: 20.19.1 - /usr/local/bin/node
    Yarn: 1.22.19 - /usr/local/bin/yarn
    npm: 10.8.2 - /usr/local/bin/npm
    pnpm: 8.15.6 - /usr/local/bin/pnpm
  npmPackages:
    @sveltejs/adapter-auto: ^4.0.0 => 4.0.0 
    @sveltejs/kit: ^2.16.0 => 2.20.7 
    @sveltejs/vite-plugin-svelte: ^5.0.0 => 5.0.3 
    svelte: ^5.25.0 => 5.28.2 
    vite: ^6.2.5 => 6.3.2 

Severity

serious, but I can work around it

Additional Information

No response

Start with the linked StackBlitz reproduction and compare the root layout.ts setting export const ssr = false with the behavior of hooks.server.ts on the initial page request. Trace the server request path and +server.ts endpoint behavior; done means the hook is not run for the initial page request when SSR is disabled, while endpoint requests retain the expected behavior.