diff --git a/packages/cli/script/generate-sdk.ts b/packages/cli/script/generate-sdk.ts
index bd24e77f3..1cb4c5308 100644
--- a/packages/cli/script/generate-sdk.ts
+++ b/packages/cli/script/generate-sdk.ts
@@ -160,7 +160,7 @@ function extractSdkFlags(command: Command): SdkFlagInfo[] {
     flags.push({
       name,
       kind,
-      tsType,
+      tsType: def.variadic ? `Array<${tsType}>` : tsType,
       optional,
       default: def.default,
       brief: def.brief,
diff --git a/packages/cli/test/lib/sdk-flag-types.test.ts b/packages/cli/test/lib/sdk-flag-types.test.ts
new file mode 100644
index 000000000..9986ad9ef
--- /dev/null
+++ b/packages/cli/test/lib/sdk-flag-types.test.ts
@@ -0,0 +1,33 @@
+/**
+ * Unit Tests for Generated SDK Flag Types
+ *
+ * Stricli passes variadic flags to a command as arrays, and the SDK forwards flags to the
+ * handler unchanged. The generator used to declare them with their element type, so
+ * `sdk.auth.login({ scope: "org:read" })` type-checked and then failed inside the handler
+ * (`flags.scope.flatMap is not a function`).
+ */
+
+import { readFileSync } from "node:fs";
+import { fileURLToPath } from "node:url";
+import { describe, expect, test } from "vitest";
+
+const declarations = readFileSync(
+  fileURLToPath(new URL("../../src/sdk.generated.d.cts", import.meta.url)),
+  "utf-8"
+);
+
+function paramsType(name: string): string {
+  const start = declarations.indexOf(`export type ${name} = {`);
+  if (start === -1) {
+    throw new Error(`${name} is missing from the generated SDK declarations`);
+  }
+  return declarations.slice(start, declarations.indexOf("\n};", start));
+}
+
+describe("generated SDK flag types", () => {
+  test("declares variadic flags as arrays and keeps scalar flags scalar", () => {
+    const login = paramsType("AuthLoginParams");
+    expect(login).toContain("scope?: Array<string>;");
+    expect(login).toContain("token?: string;");
+  });
+});