diff --git a/packages/cli/src/utils/__tests__/workspace.spec.ts b/packages/cli/src/utils/__tests__/workspace.spec.ts
new file mode 100644
index 0000000000..3c7112256b
--- /dev/null
+++ b/packages/cli/src/utils/__tests__/workspace.spec.ts
@@ -0,0 +1,259 @@
+import fs from 'node:fs';
+import os from 'node:os';
+import path from 'node:path';
+
+import { afterEach, beforeEach, describe, expect, it } from 'vitest';
+import { parse as parseYaml } from 'yaml';
+
+import { DependencyType, PackageManager, type WorkspaceInfo } from '../../types/index.ts';
+import {
+  discoverWorkspacePackages,
+  findPackageJsonFilesFromPatterns,
+  updatePackageJsonWithDeps,
+  updateWorkspaceConfig,
+} from '../workspace.ts';
+
+let tmpDir: string;
+
+beforeEach(() => {
+  tmpDir = fs.mkdtempSync(path.join(os.tmpdir(), 'vp-workspace-test-'));
+});
+
+afterEach(() => {
+  fs.rmSync(tmpDir, { recursive: true, force: true });
+});
+
+function writeJson(p: string, data: unknown) {
+  fs.mkdirSync(path.dirname(p), { recursive: true });
+  fs.writeFileSync(p, JSON.stringify(data, null, 2));
+}
+
+function makeWorkspaceInfo(overrides: Partial<WorkspaceInfo> = {}): WorkspaceInfo {
+  return {
+    rootDir: tmpDir,
+    packageManager: PackageManager.pnpm,
+    packageManagerVersion: 'latest',
+    isMonorepo: true,
+    monorepoScope: '',
+    workspacePatterns: [],
+    parentDirs: [],
+    packages: [],
+    downloadPackageManager: {
+      name: '',
+      installDir: '',
+      binPrefix: '',
+      packageName: '',
+      version: '',
+    },
+    ...overrides,
+  };
+}
+
+describe('updateWorkspaceConfig pattern derivation', () => {
+  it('derives "packages/*" from a nested project path (pnpm)', () => {
+    fs.writeFileSync(path.join(tmpDir, 'pnpm-workspace.yaml'), "packages:\n  - 'apps/*'\n");
+    updateWorkspaceConfig('packages/my-app', makeWorkspaceInfo({ workspacePatterns: ['apps/*'] }));
+    const content = fs.readFileSync(path.join(tmpDir, 'pnpm-workspace.yaml'), 'utf8');
+    const parsed = parseYaml(content) as { packages: string[] };
+    expect(parsed.packages).toEqual(['apps/*', 'packages/*']);
+  });
+
+  it('derives "foo/bar/*" from a deeply nested project path (pnpm)', () => {
+    fs.writeFileSync(path.join(tmpDir, 'pnpm-workspace.yaml'), 'packages: []\n');
+    updateWorkspaceConfig('foo/bar/app', makeWorkspaceInfo({ workspacePatterns: [] }));
+    const parsed = parseYaml(fs.readFileSync(path.join(tmpDir, 'pnpm-workspace.yaml'), 'utf8')) as {
+      packages: string[];
+    };
+    expect(parsed.packages).toEqual(['foo/bar/*']);
+  });
+
+  it('keeps a single-segment project path literal (pnpm)', () => {
+    fs.writeFileSync(path.join(tmpDir, 'pnpm-workspace.yaml'), 'packages: []\n');
+    updateWorkspaceConfig('website', makeWorkspaceInfo({ workspacePatterns: [] }));
+    const parsed = parseYaml(fs.readFileSync(path.join(tmpDir, 'pnpm-workspace.yaml'), 'utf8')) as {
+      packages: string[];
+    };
+    expect(parsed.packages).toEqual(['website']);
+  });
+
+  it('skips update when the project path already matches an existing pattern', () => {
+    fs.writeFileSync(path.join(tmpDir, 'pnpm-workspace.yaml'), "packages:\n  - 'apps/*'\n");
+    updateWorkspaceConfig('apps/admin', makeWorkspaceInfo({ workspacePatterns: ['apps/*'] }));
+    const parsed = parseYaml(fs.readFileSync(path.join(tmpDir, 'pnpm-workspace.yaml'), 'utf8')) as {
+      packages: string[];
+    };
+    expect(parsed.packages).toEqual(['apps/*']);
+  });
+
+  it.each([PackageManager.npm, PackageManager.bun, PackageManager.yarn])(
+    'skips update when the project path already matches an existing pattern (%s)',
+    (packageManager) => {
+      writeJson(path.join(tmpDir, 'package.json'), {
+        name: 'root',
+        workspaces: ['apps/*'],
+      });
+      updateWorkspaceConfig(
+        'apps/admin',
+        makeWorkspaceInfo({ packageManager, workspacePatterns: ['apps/*'] }),
+      );
+      const pkg = JSON.parse(fs.readFileSync(path.join(tmpDir, 'package.json'), 'utf8'));
+      expect(pkg.workspaces).toEqual(['apps/*']);
+    },
+  );
+
+  it('initializes packages key when pnpm-workspace.yaml has no packages field', () => {
+    fs.writeFileSync(path.join(tmpDir, 'pnpm-workspace.yaml'), 'catalog:\n  foo: ^1.0.0\n');
+    updateWorkspaceConfig('website', makeWorkspaceInfo({ workspacePatterns: [] }));
+    const parsed = parseYaml(fs.readFileSync(path.join(tmpDir, 'pnpm-workspace.yaml'), 'utf8')) as {
+      packages: string[];
+      catalog: Record<string, string>;
+    };
+    expect(parsed.packages).toEqual(['website']);
+    expect(parsed.catalog).toEqual({ foo: '^1.0.0' });
+  });
+
+  it('initializes workspaces field when package.json has none (npm)', () => {
+    writeJson(path.join(tmpDir, 'package.json'), { name: 'root' });
+    updateWorkspaceConfig(
+      'packages/foo',
+      makeWorkspaceInfo({ packageManager: PackageManager.npm, workspacePatterns: [] }),
+    );
+    const pkg = JSON.parse(fs.readFileSync(path.join(tmpDir, 'package.json'), 'utf8'));
+    expect(pkg.workspaces).toEqual(['packages/*']);
+  });
+
+  it('appends to npm-style array workspaces in package.json', () => {
+    writeJson(path.join(tmpDir, 'package.json'), {
+      name: 'root',
+      workspaces: ['apps/*'],
+    });
+    updateWorkspaceConfig(
+      'packages/foo',
+      makeWorkspaceInfo({
+        packageManager: PackageManager.npm,
+        workspacePatterns: ['apps/*'],
+      }),
+    );
+    const pkg = JSON.parse(fs.readFileSync(path.join(tmpDir, 'package.json'), 'utf8'));
+    expect(pkg.workspaces).toEqual(['apps/*', 'packages/*']);
+  });
+
+  it('preserves object-form workspaces (bun catalogs / yarn nohoist)', () => {
+    writeJson(path.join(tmpDir, 'package.json'), {
+      name: 'root',
+      workspaces: {
+        packages: ['apps/*'],
+        catalog: { react: '^19.0.0' },
+      },
+    });
+    updateWorkspaceConfig(
+      'packages/foo',
+      makeWorkspaceInfo({
+        packageManager: PackageManager.bun,
+        workspacePatterns: ['apps/*'],
+      }),
+    );
+    const pkg = JSON.parse(fs.readFileSync(path.join(tmpDir, 'package.json'), 'utf8'));
+    expect(pkg.workspaces).toEqual({
+      packages: ['apps/*', 'packages/*'],
+      catalog: { react: '^19.0.0' },
+    });
+  });
+});
+
+describe('discoverWorkspacePackages', () => {
+  it('returns an empty list when no patterns are provided', () => {
+    expect(discoverWorkspacePackages([], tmpDir)).toEqual([]);
+  });
+
+  it('finds packages matching workspace patterns', () => {
+    writeJson(path.join(tmpDir, 'packages/foo/package.json'), {
+      name: 'foo',
+      version: '1.0.0',
+      description: 'a foo',
+    });
+    writeJson(path.join(tmpDir, 'packages/bar/package.json'), {
+      name: 'bar',
+      version: '2.0.0',
+    });
+    // package.json without "name" must be skipped
+    writeJson(path.join(tmpDir, 'packages/nameless/package.json'), {
+      version: '0.0.0',
+    });
+
+    const packages = discoverWorkspacePackages(['packages/*'], tmpDir);
+    const names = packages.map((p) => p.name).toSorted();
+    expect(names).toEqual(['bar', 'foo']);
+    const foo = packages.find((p) => p.name === 'foo')!;
+    expect(foo.path).toBe(path.join('packages', 'foo'));
+    expect(foo.description).toBe('a foo');
+    expect(foo.version).toBe('1.0.0');
+    expect(foo.isTemplatePackage).toBe(false);
+  });
+
+  it('flags packages keyworded as vite-plus-template / bingo-template', () => {
+    writeJson(path.join(tmpDir, 'pkgs/vp/package.json'), {
+      name: 'vp',
+      keywords: ['vite-plus-template'],
+    });
+    writeJson(path.join(tmpDir, 'pkgs/bg/package.json'), {
+      name: 'bg',
+      keywords: ['bingo-template'],
+    });
+    writeJson(path.join(tmpDir, 'pkgs/bd/package.json'), {
+      name: 'bd',
+      dependencies: { bingo: '*' },
+    });
+    writeJson(path.join(tmpDir, 'pkgs/plain/package.json'), { name: 'plain' });
+
+    const packages = discoverWorkspacePackages(['pkgs/*'], tmpDir);
+    const map = Object.fromEntries(packages.map((p) => [p.name, p.isTemplatePackage]));
+    expect(map).toEqual({ vp: true, bg: true, bd: true, plain: false });
+  });
+
+  it('ignores node_modules during discovery', () => {
+    writeJson(path.join(tmpDir, 'packages/a/package.json'), { name: 'a' });
+    writeJson(path.join(tmpDir, 'packages/a/node_modules/dep/package.json'), {
+      name: 'dep',
+    });
+    const packages = discoverWorkspacePackages(['packages/*'], tmpDir);
+    expect(packages.map((p) => p.name)).toEqual(['a']);
+  });
+});
+
+describe('updatePackageJsonWithDeps', () => {
+  it('adds workspace:* deps under the requested dependency type', () => {
+    writeJson(path.join(tmpDir, 'apps/app/package.json'), { name: 'app' });
+    updatePackageJsonWithDeps(tmpDir, 'apps/app', ['shared', 'ui'], DependencyType.dependencies);
+    const pkg = JSON.parse(fs.readFileSync(path.join(tmpDir, 'apps/app/package.json'), 'utf8'));
+    expect(pkg.dependencies).toEqual({ shared: 'workspace:*', ui: 'workspace:*' });
+  });
+
+  it('preserves existing entries of the same dependency type', () => {
+    writeJson(path.join(tmpDir, 'apps/app/package.json'), {
+      name: 'app',
+      devDependencies: { existing: '^1.0.0' },
+    });
+    updatePackageJsonWithDeps(tmpDir, 'apps/app', ['lint'], DependencyType.devDependencies);
+    const pkg = JSON.parse(fs.readFileSync(path.join(tmpDir, 'apps/app/package.json'), 'utf8'));
+    expect(pkg.devDependencies).toEqual({ existing: '^1.0.0', lint: 'workspace:*' });
+  });
+});
+
+describe('findPackageJsonFilesFromPatterns', () => {
+  it('returns absolute paths for matching package.json files', () => {
+    writeJson(path.join(tmpDir, 'packages/a/package.json'), { name: 'a' });
+    writeJson(path.join(tmpDir, 'packages/b/package.json'), { name: 'b' });
+    const result = findPackageJsonFilesFromPatterns(['packages/*'], tmpDir).toSorted();
+    expect(result).toEqual(
+      [
+        path.join(tmpDir, 'packages/a/package.json'),
+        path.join(tmpDir, 'packages/b/package.json'),
+      ].toSorted(),
+    );
+  });
+
+  it('returns empty when given no patterns', () => {
+    expect(findPackageJsonFilesFromPatterns([], tmpDir)).toEqual([]);
+  });
+});
diff --git a/packages/cli/src/utils/workspace.ts b/packages/cli/src/utils/workspace.ts
index c1e996e3f4..5ed75b1de5 100644
--- a/packages/cli/src/utils/workspace.ts
+++ b/packages/cli/src/utils/workspace.ts
@@ -185,14 +185,9 @@ export function updateWorkspaceConfig(projectPath: string, workspaceInfo: Worksp
   }
 
   // Derive pattern from project path (e.g., "packages/my-app" -> "packages/*", "website" -> "website", "foo/bar/app" -> "foo/bar/*")
-  let pattern = path.dirname(projectPath);
-  if (!pattern) {
-    // "website" -> "website"
-    pattern = projectPath;
-  } else {
-    // "foo/bar/app" -> "foo/bar/*"
-    pattern = `${pattern}/*`;
-  }
+  const parentDir = path.dirname(projectPath);
+  // path.dirname returns '.' for single-segment paths, treat that as no parent
+  const pattern = parentDir === '.' ? projectPath : `${parentDir}/*`;
 
   if (workspaceInfo.packageManager === PackageManager.pnpm) {
     editYamlFile(path.join(workspaceInfo.rootDir, 'pnpm-workspace.yaml'), (doc) => {