svelte-kit sync generates types twice #17394

Describe the bug

Since 3.0, svelte-kit sync resolves the Vite config with vite.resolveConfig(..., 'build') (load_vite_config in src/cli.js). During that call, the config hook of the build plugin (src/exports/vite/build/index.js) already runs a full sync:

manifest_data = create_manifest_data(kit, root);
set_manifest_data(manifest_data);
sync.all(kit, root, manifest_data);

sync.all includes write_all_types. After load_vite_config returns, the CLI calls sync.all_types(sveltekit_config, vite_config.root). That builds the manifest and writes all types a second time.

On an app with ~120 route modules, a CPU profile of svelte-kit sync shows ~160–220ms in the plugin's sync and another ~115ms in the CLI's all_types. The whole command takes ~0.8s, so the repeat is about 15% of it. The code is the same on main.

The CLI could skip all_types when the plugin has already synced, or the plugin could skip its sync when the CLI invokes it.

Reproduction

1. In any SvelteKit 3 app with a few routes, run:

   node --cpu-prof --cpu-prof-dir=prof node_modules/@sveltejs/kit/svelte-kit.js sync

2. Open the profile, for example in Chrome DevTools. create_manifest_data and write_all_types each run twice: once under exports/vite/build/index.js (config handler, via sync.all) and once under cli.js (via sync.all_types).

Logs

No response

System Info

System: macOS 26 (Darwin 25.6.0), Apple Silicon
Node: 24.21.0
@sveltejs/kit: 3.0.0 (the code paths are unchanged on main / 3.0.1)
vite: 8.3.2
svelte: 5.57.2

Severity

annoyance

Additional Information

We run svelte-kit sync before every type check (svelte-kit sync && svelte-check), so the duplicate cost adds up during local development.