diff --git a/vitest.config.ts b/vitest.config.ts
new file mode 100644
index 0000000..58b94e3
--- /dev/null
+++ b/vitest.config.ts
@@ -0,0 +1,11 @@
+import { defineConfig } from "vitest/config";
+
+export default defineConfig({
+  test: {
+    // Many tests run real builds, validations and packed CLIs against temp
+    // projects. They take 1-4s locally, and the shared CI runners run the
+    // suite in parallel at a fraction of that speed, so vitest's 5s default
+    // fails tests that are slow, not broken.
+    testTimeout: 30_000,
+  },
+});