diff --git a/packages/server/test/setup-env.ts b/packages/server/test/setup-env.ts
new file mode 100644
index 00000000..16c5d2c3
--- /dev/null
+++ b/packages/server/test/setup-env.ts
@@ -0,0 +1,7 @@
+// Vitest setup: provides test-only defaults for env vars that config.ts
+// requires at module-load time. Without this, every test that transitively
+// imports a server module aborts during import when .env is absent (fresh
+// worktrees, CI without secrets, contributor first-run). Real .env values
+// still take precedence — `??=` only fills holes.
+
+process.env.JWT_SECRET ??= 'test-only-jwt-secret-not-for-production-use!!';
diff --git a/packages/server/vitest.config.ts b/packages/server/vitest.config.ts
new file mode 100644
index 00000000..9605564b
--- /dev/null
+++ b/packages/server/vitest.config.ts
@@ -0,0 +1,7 @@
+import { defineConfig } from 'vitest/config';
+
+export default defineConfig({
+  test: {
+    setupFiles: ['./test/setup-env.ts'],
+  },
+});