fix: don't reinclude excluded dependencies in automatic handling (#159)

* wip: take existing include and exclude config into account when filtering in automatic dependency optimization

* fix: don't reinclude excluded dependencies in automatic handling

Author: dominikg

.changeset/strange-brooms-crash.md

@@ -0,0 +1,5 @@
+---
+'@sveltejs/vite-plugin-svelte': patch
+---
+
+Improve automatic dependency pre-bundling by not reincluding dependencies that are already present in optimizeDeps.exclude

packages/vite-plugin-svelte/src/utils/options.ts

@@ -219,28 +219,36 @@ function buildOptimizeDepsForSvelte(
 	// include svelte imports for optimization unless explicitly excluded
 	const include: string[] = [];
 	const exclude: string[] = ['svelte-hmr'];
-	const isSvelteExcluded = optimizeDeps?.exclude?.includes('svelte');
-	if (!isSvelteExcluded) {
+	const isIncluded = (dep: string) => include.includes(dep) || optimizeDeps?.include?.includes(dep);
+	const isExcluded = (dep: string) => {
+		return (
+			exclude.includes(dep) ||
+			// vite optimizeDeps.exclude works for subpackages too
+			// see https://github.com/vitejs/vite/blob/c87763c1418d1ba876eae13d139eba83ac6f28b2/packages/vite/src/node/optimizer/scan.ts#L293
+			optimizeDeps?.exclude?.some((id) => dep === id || id.startsWith(`${dep}/`))
+		);
+	};
+	if (!isExcluded('svelte')) {
 		const svelteImportsToInclude = SVELTE_IMPORTS.filter((x) => x !== 'svelte/ssr'); // not used on clientside
 		log.debug(
 			`adding bare svelte packages to optimizeDeps.include: ${svelteImportsToInclude.join(', ')} `
 		);
-		include.push(...svelteImportsToInclude.filter((x) => !optimizeDeps?.include?.includes(x)));
+		include.push(...svelteImportsToInclude.filter((x) => !isIncluded(x)));
 	} else {
 		log.debug('"svelte" is excluded in optimizeDeps.exclude, skipped adding it to include.');
 	}
 
 	const svelteDepsToExclude = Array.from(new Set(svelteDeps.map((dep) => dep.name))).filter(
-		(dep) => !optimizeDeps?.include?.includes(dep)
+		(dep) => !isIncluded(dep)
 	);
 	log.debug(`automatically excluding found svelte dependencies: ${svelteDepsToExclude.join(', ')}`);
-	exclude.push(...svelteDepsToExclude.filter((x) => !optimizeDeps?.exclude?.includes(x)));
+	exclude.push(...svelteDepsToExclude.filter((x) => !isExcluded(x)));
 
 	const transitiveDepsToInclude = svelteDeps
-		.filter((dep) => svelteDepsToExclude.includes(dep.name))
+		.filter((dep) => isExcluded(dep.name))
 		.flatMap((dep) =>
 			Object.keys(dep.pkg.dependencies || {})
-				.filter((depOfDep) => !svelteDepsToExclude.includes(depOfDep))
+				.filter((depOfDep) => !isExcluded(depOfDep))
 				.map((depOfDep) => dep.path.concat(dep.name, depOfDep).join(' > '))
 		);
 	log.debug(