Custom SvelteKit hooks and params locations (files option) aren't typed by svelte-check #3162

Describe the bug

With hooks moved through the files option, svelte-check's default mode and --tsgo-experimental-api don't add the SvelteKit types to them, so an untyped handle reports implicit any. --tsgo and --incremental type it. With files.src set, no mode types the hooks or param matchers under it.

• JSOrTSDocumentSnapshot only reads the config after a file has matched the default locations, and then assigns with ||= over the non-empty defaults, so a configured location never applies: DocumentSnapshot.ts#L652-L660.
• The --tsgo-experimental-api provider has its own hard-coded defaults: DiagnosticsProvider.ts#L341-L346.
• No mode reads files.src; incremental.ts#L107-L119 is the overlay modes' version.

Reproduction

package.json:

{
  "private": true,
  "type": "module",
  "devDependencies": {
    "@sveltejs/kit": "2.70.3",
    "@typescript/native": "npm:typescript@7.0.2",
    "svelte": "5.57.2",
    "svelte-check": "4.7.7",
    "typescript": "6.0.3"
  }
}

svelte.config.js:

export default {
	kit: {
		files: {
			hooks: { server: 'src/server/hooks' }
		}
	}
};

tsconfig.json:

{ "compilerOptions": { "target": "ESNext", "module": "ESNext", "moduleResolution": "bundler", "strict": true, "noEmit": true, "skipLibCheck": true }, "include": ["src/**/*.ts", "src/**/*.svelte"] }

src/App.svelte:

<p>app</p>

src/server/hooks.ts:

export const handle = ({ event, resolve }) => resolve(event);

npm install
npx svelte-check --tsconfig ./tsconfig.json --output machine
npx svelte-check --tsconfig ./tsconfig.json --output machine --incremental
npx svelte-check --tsconfig ./tsconfig.json --output machine --tsgo
npx svelte-check --tsconfig ./tsconfig.json --output machine --tsgo-experimental-api

Output, without the timestamps and the START lines:

# default (--tsgo-experimental-api prints the same, with "COMPLETED 2 FILES")
ERROR "src/server/hooks.ts" 1:26 "Binding element 'event' implicitly has an 'any' type."
ERROR "src/server/hooks.ts" 1:33 "Binding element 'resolve' implicitly has an 'any' type."
COMPLETED 112 FILES 2 ERRORS 0 WARNINGS 1 FILES_WITH_PROBLEMS
# --incremental and --tsgo
COMPLETED 2 FILES 0 ERRORS 0 WARNINGS 0 FILES_WITH_PROBLEMS

For files.src, change svelte.config.js to export default { kit: { files: { src: 'app' } } };, the include to ["app/**/*.ts", "app/**/*.svelte"], and move the files to:

• app/App.svelte: <p>app</p>
• app/hooks.server.ts: export const handle = ({ event, resolve }) => resolve(event);
• app/params/id.ts: export const match = (param) => /^\d+$/.test(param);

All four modes then report:

ERROR "app/hooks.server.ts" 1:26 "Binding element 'event' implicitly has an 'any' type."
ERROR "app/hooks.server.ts" 1:33 "Binding element 'resolve' implicitly has an 'any' type."
ERROR "app/params/id.ts" 1:23 "Parameter 'param' implicitly has an 'any' type."

Expected behaviour

The hooks and params files at the configured locations get the same types as at the default ones.

Fix direction

One helper for all modes that reads files, derives the defaults from files.src, and resolves configured locations against the config's directory. Matching them as plain path suffixes, as the overlay modes do now, also types unrelated files (hooks.server: 'server' matches observer.ts and other/server.ts), so a configured location has to be compared as a path. #3165 does this.

System Info

• svelte-check 4.7.7, @sveltejs/kit 2.70.3, Svelte 5.57.2, TypeScript 6.0.3, @typescript/native as npm:typescript@7.0.2
• Node 24.16.0, macOS arm64

Which package is the issue about?

svelte-check

Additional Information, eg. Screenshots

The TypeScript plugin that types .ts files in the editor has its own copy of the defaults too; I haven't looked into that one.