fix: preserve cross-package generic types in emitDts

Update moduleResolution from node10 to node16 to properly resolve generic
types across package boundaries in monorepo setups.

Previously, cross-package generic type information was lost during .d.ts
generation, causing types like `GenericType<T>` to be emitted as `any`.

- Add test case for cross-package generic type preservation

Author: mtsgrd

packages/svelte2tsx/src/emitDts.ts

@@ -111,9 +111,7 @@ function loadTsconfig(config: EmitDtsConfig, svelteMap: SvelteMap) {
         options: {
             ...options,
             noEmit: false, // Set to true in case of jsconfig, force false, else nothing is emitted
-            moduleResolution:
-                // NodeJS: up to 4.9, Node10: since 5.0
-                (ts.ModuleResolutionKind as any).NodeJs ?? ts.ModuleResolutionKind.Node10, // Classic if not set, which gives wrong results
+            moduleResolution: ts.ModuleResolutionKind.Node16,
             declaration: true, // Needed for d.ts file generation
             emitDeclarationOnly: true, // We only want d.ts file generation
             declarationDir: config.declarationDir, // Where to put the declarations

packages/svelte2tsx/test/emitDts/samples/cross-package-generic-types/README.md

@@ -0,0 +1,22 @@
+# Cross-Package Generic Types Test
+
+This test validates that generic type information is correctly preserved when importing generic classes from external packages during `.d.ts` generation.
+
+## Issue
+Before the fix, when using modern module resolution (bundler/node16), cross-package imports of generic classes would lose their type information and fall back to `any` in generated declaration files.
+
+## Test Structure
+- `core-package/` - Mock external package containing `GenericToken<T>` class
+- `src/consumer.ts` - Consumes the generic class with type parameters
+- `expected/` - Expected output showing preserved generic types
+
+## Key Test Case
+```typescript
+// This should preserve the generic type as GenericToken<MyService>
+// Before the fix: compiled as 'any' due to module resolution issues
+// After the fix: correctly typed as GenericToken<MyService>
+export const SERVICE_TOKEN = new GenericToken<MyService>('MyService');
+```
+
+## Fix
+Updated `emitDts.ts` to use modern module resolution (bundler/node16) instead of legacy node10 resolution.

packages/svelte2tsx/test/emitDts/samples/cross-package-generic-types/core-package/package.json

@@ -0,0 +1,12 @@
+{
+	"name": "@test/core",
+	"version": "1.0.0",
+	"type": "module",
+	"exports": {
+		".": {
+			"types": "./dist/index.d.ts",
+			"import": "./dist/index.js"
+		}
+	}
+}
+

packages/svelte2tsx/test/emitDts/samples/cross-package-generic-types/expected/consumer.d.ts

@@ -0,0 +1,13 @@
+import { GenericToken } from '@test/core';
+export declare class MyService {
+    private name;
+    constructor(name: string);
+    getName(): string;
+}
+export declare const SERVICE_TOKEN: GenericToken<MyService>;
+export declare const ANNOTATED_TOKEN: GenericToken<MyService>;
+export declare const ASSERTION_TOKEN: GenericToken<MyService>;
+export declare class AnotherService {
+    value: number;
+}
+export declare const ANOTHER_TOKEN: GenericToken<AnotherService>;

packages/svelte2tsx/test/emitDts/samples/cross-package-generic-types/expected/index.d.ts

@@ -0,0 +1 @@
+export * from './consumer.js';

packages/svelte2tsx/test/emitDts/samples/cross-package-generic-types/package.json

@@ -0,0 +1,9 @@
+{
+	"name": "test-cross-package-generics",
+	"version": "0.0.1",
+	"type": "module",
+	"dependencies": {
+		"@test/core": "1.0.0"
+	}
+}
+

packages/svelte2tsx/test/emitDts/samples/cross-package-generic-types/src/consumer.ts

@@ -0,0 +1,22 @@
+import { GenericToken } from '@test/core';
+
+export class MyService {
+	constructor(private name: string) {}
+	getName() { return this.name; }
+}
+
+// This should preserve the generic type as GenericToken<MyService>
+// Before the fix, this would be compiled as 'any' due to module resolution issues
+export const SERVICE_TOKEN = new GenericToken<MyService>('MyService');
+
+// These explicit annotations should work regardless
+export const ANNOTATED_TOKEN: GenericToken<MyService> = new GenericToken<MyService>('MyService');
+export const ASSERTION_TOKEN = new GenericToken<MyService>('MyService') as GenericToken<MyService>;
+
+// Test with different generic types
+export class AnotherService {
+	value = 42;
+}
+
+export const ANOTHER_TOKEN = new GenericToken<AnotherService>('AnotherService');
+

packages/svelte2tsx/test/emitDts/samples/cross-package-generic-types/src/index.ts

@@ -0,0 +1,2 @@
+export * from './consumer.js';
+

packages/svelte2tsx/test/emitDts/samples/cross-package-generic-types/tsconfig.json

@@ -0,0 +1,14 @@
+{
+	"compilerOptions": {
+		"target": "ES2022",
+		"lib": ["ES2022", "DOM"],
+		"module": "ESNext",
+		"declaration": true,
+		"strict": true,
+		"skipLibCheck": true,
+		"esModuleInterop": true,
+		"allowSyntheticDefaultImports": true
+	},
+	"include": ["src/**/*"]
+}
+