feat(evals): add eval coverage report command (#28169)

scripts/eval-coverage-cli.ts

@@ -0,0 +1,51 @@
+#!/usr/bin/env tsx
+
+/**
+ * @license
+ * Copyright 2026 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import { collectInventory } from './utils/eval-inventory.js';
+import { buildToolRegistry } from './utils/tool-registry.js';
+import {
+  computeCoverage,
+  formatCoverageReport,
+} from './utils/eval-coverage.js';
+
+async function main() {
+  const rootFlagIndex = process.argv.indexOf('--root');
+  const rootFlagValue =
+    rootFlagIndex !== -1 ? process.argv[rootFlagIndex + 1] : undefined;
+
+  if (rootFlagIndex !== -1 && rootFlagValue === undefined) {
+    console.error(
+      'Error: --root requires a directory path argument but none was provided.',
+    );
+    process.exit(1);
+  }
+  if (rootFlagValue && rootFlagValue.startsWith('--')) {
+    console.error(
+      `Error: --root value "${rootFlagValue}" looks like a flag. Provide a valid directory path.`,
+    );
+    process.exit(1);
+  }
+
+  const repoRoot = rootFlagValue ?? process.cwd();
+  const inventory = await collectInventory(repoRoot);
+
+  if (inventory.totalFiles === 0) {
+    console.error('No eval files found under evals/.');
+    process.exit(1);
+  }
+
+  const registry = buildToolRegistry();
+  const result = computeCoverage(inventory, registry);
+
+  console.log(formatCoverageReport(result));
+}
+
+main().catch((error) => {
+  console.error('Fatal error:', error);
+  process.exit(1);
+});