fix(language-server): follow project references when resolving the owning tsconfig

A solution-style tsconfig (`files: []` plus `references`) includes nothing itself.
Nuxt 3 generates exactly that shape at the project root, pointing at
`.nuxt/tsconfig.*.json` — without following the references those projects fell
back to the empty simple project, losing their aliases and compiler options.

`searchConfig` now recurses into `projectReferences` (with a visited set) before
walking further up, and a solution-style fixture pins the behaviour.

Author: johnsoncodehk

packages/language-server/lib/project.ts

@@ -31,17 +31,18 @@ export function createProjectResolver(ts: typeof import('typescript')): ProjectR
 	}
 
 	function search(fileName: string) {
+		const visited = new Set<string>();
 		let dir = path.dirname(fileName);
 		while (true) {
 			const configFileName = ts.findConfigFile(dir, ts.sys.fileExists);
 			if (!configFileName) {
 				return undefined;
 			}
-			if (isOwned(configFileName, fileName)) {
-				return configFileName;
+			const owned = searchConfig(configFileName, fileName, visited);
+			if (owned) {
+				return owned;
 			}
-			// The nearest tsconfig does not include the file (e.g. a solution-style config that only
-			// holds references); keep looking in the parent directory.
+			// The nearest tsconfig does not include the file; keep looking in the parent directory.
 			const parent = path.dirname(path.dirname(configFileName));
 			if (parent === path.dirname(configFileName)) {
 				return undefined;
@@ -50,6 +51,28 @@ export function createProjectResolver(ts: typeof import('typescript')): ProjectR
 		}
 	}
 
+	/**
+	 * A solution-style tsconfig (`files: []` plus `references`) does not include anything itself —
+	 * Nuxt 3 generates exactly this shape at the project root, pointing at `.nuxt/tsconfig.*.json`.
+	 * Follow the references to find the config that actually owns the file.
+	 */
+	function searchConfig(configFileName: string, fileName: string, visited: Set<string>): string | undefined {
+		const key = configFileName.replace(/\\/g, '/').toLowerCase();
+		if (visited.has(key)) {
+			return undefined;
+		}
+		visited.add(key);
+		if (isOwned(configFileName, fileName)) {
+			return configFileName;
+		}
+		for (const reference of getCommandLine(configFileName)?.projectReferences ?? []) {
+			const owned = searchConfig(reference.path, fileName, visited);
+			if (owned) {
+				return owned;
+			}
+		}
+	}
+
 	const resolver: ProjectResolver = {
 		getConfigFileName(fileName) {
 			if (!fileToConfig.has(fileName)) {

packages/language-server/tests/project.spec.ts

@@ -18,6 +18,17 @@ test('resolves the tsconfig that owns a file', () => {
 	resolver.dispose();
 });
 
+test('follows project references of a solution-style tsconfig', () => {
+	const resolver = createProjectResolver(ts);
+	// Nuxt 3 shape: the root tsconfig only holds references, the generated config owns the files.
+	const appFile = path.join(testWorkspacePath, 'tsconfigSolution/src/App.vue');
+
+	expect(normalize(resolver.getConfigFileName(appFile)!)).toMatch(/tsconfigSolution\/generated\/tsconfig\.app\.json$/);
+	expect(resolver.getCommandLine(appFile)!.options.paths).toEqual({ '@solution/*': ['../src/*'] });
+
+	resolver.dispose();
+});
+
 test('resolves module names with the owning project options', () => {
 	const resolver = createProjectResolver(ts);
 	const firstOptions = resolver.getCommandLine(firstProjectFile)!.options;

test-workspace/tsconfigSolution/generated/tsconfig.app.json

@@ -0,0 +1,8 @@
+{
+	"include": ["../**/*"],
+	"compilerOptions": {
+		"paths": {
+			"@solution/*": ["../src/*"]
+		}
+	}
+}

test-workspace/tsconfigSolution/src/App.vue

@@ -0,0 +1,5 @@
+<script setup lang="ts">
+const msg = "hi";
+</script>
+
+<template><div>{{ msg }}</div></template>

test-workspace/tsconfigSolution/src/helper.ts

@@ -0,0 +1 @@
+export const helper = 1;

test-workspace/tsconfigSolution/tsconfig.json

@@ -0,0 +1,4 @@
+{
+	"files": [],
+	"references": [{ "path": "./generated/tsconfig.app.json" }]
+}