diff --git a/apps/sdk-test/@useautumn-sdk.d.ts b/apps/sdk-test/@useautumn-sdk.d.ts
index a20c900bc..323902fb0 100644
--- a/apps/sdk-test/@useautumn-sdk.d.ts
+++ b/apps/sdk-test/@useautumn-sdk.d.ts
@@ -1,6 +1,8 @@
 // AUTO-GENERATED by atmn pull
 // DO NOT EDIT MANUALLY
 
+import type {} from "@useautumn/sdk";
+
 declare module '@useautumn/sdk' {
   // Features
   export const chat_messages: Feature;
diff --git a/apps/sdk-test/app/scenarios/core/use-events/page.tsx b/apps/sdk-test/app/scenarios/core/use-events/page.tsx
index 8a1e710fc..32da7ab64 100644
--- a/apps/sdk-test/app/scenarios/core/use-events/page.tsx
+++ b/apps/sdk-test/app/scenarios/core/use-events/page.tsx
@@ -174,6 +174,7 @@ export default function UseEventsScenarioPage() {
             <Button
               size="sm"
               variant="outline"
+              // @ts-expect-error
               onClick={() => listEvents.refetch()}
               disabled={listEvents.isFetching}
             >
diff --git a/apps/sdk-test/failOpenTest.ts b/apps/sdk-test/failOpenTest.ts
new file mode 100644
index 000000000..b37b63a1c
--- /dev/null
+++ b/apps/sdk-test/failOpenTest.ts
@@ -0,0 +1,114 @@
+import { Autumn } from "autumn-js";
+
+const FAKE_URL =
+  "https://totallynotarealdomaingeneratedbyclaudetomakethetestsworktofail.co";
+
+let passed = 0;
+let failed = 0;
+
+function assert(label: string, condition: boolean) {
+  if (condition) {
+    console.log(`  PASS: ${label}`);
+    passed++;
+  } else {
+    console.error(`  FAIL: ${label}`);
+    failed++;
+  }
+}
+
+async function testCheckFailOpen() {
+  console.log("\n--- check() fail-open (enabled by default) ---");
+  const autumn = new Autumn({
+    secretKey: "sk_fake",
+    serverURL: FAKE_URL,
+    failOpen: true,
+  });
+
+  const result = await autumn.check({
+    customerId: "cus_123",
+    featureId: "messages",
+  });
+
+  assert("allowed is true", result.allowed === true);
+  assert("customerId is empty string", result.customerId === "");
+  assert("balance is null", result.balance === null);
+  console.log("Response:", JSON.stringify(result, null, 2));
+}
+
+async function testTrackFailOpen() {
+  console.log("\n--- track() fail-open (enabled by default) ---");
+  const autumn = new Autumn({
+    secretKey: "sk_fake",
+    serverURL: FAKE_URL,
+  });
+
+  const result = await autumn.track({
+    customerId: "cus_123",
+    featureId: "messages",
+    value: 1,
+  });
+
+  assert("customerId is empty string", result.customerId === "");
+  assert("value is 0", result.value === 0);
+  assert("balance is null", result.balance === null);
+  console.log("Response:", JSON.stringify(result, null, 2));
+}
+
+async function testGetCustomerFailOpen() {
+  console.log(
+    "\n--- customers.getOrCreate() fail-open (enabled by default) ---",
+  );
+  const autumn = new Autumn({
+    secretKey: "sk_fake",
+    serverURL: FAKE_URL,
+  });
+
+  const result = await autumn.customers.getOrCreate({
+    customerId: "cus_123",
+  });
+
+  assert("id is null", result.id === null);
+  assert("createdAt is 0", result.createdAt === 0);
+  assert(
+    "subscriptions is empty array",
+    Array.isArray(result.subscriptions) && result.subscriptions.length === 0,
+  );
+  assert("balances is empty object", Object.keys(result.balances).length === 0);
+  console.log("Response:", JSON.stringify(result, null, 2));
+}
+
+async function testFailOpenDisabled() {
+  console.log("\n--- check() with failOpen: false (should throw) ---");
+  const autumn = new Autumn({
+    secretKey: "sk_fake",
+    serverURL: FAKE_URL,
+    failOpen: false,
+  });
+
+  try {
+    await autumn.check({
+      customerId: "cus_123",
+      featureId: "messages",
+    });
+    assert("should have thrown", false);
+  } catch (err) {
+    assert("correctly threw error", true);
+    console.log(`  Error: ${(err as Error).message}`);
+  }
+}
+
+async function main() {
+  console.log("=== Autumn SDK Fail-Open Tests ===");
+
+  await testCheckFailOpen();
+  await testTrackFailOpen();
+  await testGetCustomerFailOpen();
+  await testFailOpenDisabled();
+
+  console.log(`\n=== Results: ${passed} passed, ${failed} failed ===`);
+  if (failed > 0) {
+    process.exit(1);
+  }
+}
+
+main().catch(console.error);
diff --git a/bun.lock b/bun.lock
index b7a88440a..353611c08 100644
--- a/bun.lock
+++ b/bun.lock
@@ -175,7 +175,7 @@
     },
     "packages/autumn-js": {
       "name": "autumn-js",
-      "version": "1.1.2",
+      "version": "1.1.3",
       "dependencies": {
         "query-string": "^9.2.2",
         "rou3": "^0.6.1",
@@ -240,7 +240,7 @@
     },
     "packages/sdk": {
       "name": "@useautumn/sdk",
-      "version": "0.10.17",
+      "version": "0.10.18",
       "dependencies": {
         "zod": "^3.25.65 || ^4.0.0",
       },
diff --git a/packages/atmn-tests/@useautumn-sdk.d.ts b/packages/atmn-tests/@useautumn-sdk.d.ts
index 3acfa889c..094753eee 100644
--- a/packages/atmn-tests/@useautumn-sdk.d.ts
+++ b/packages/atmn-tests/@useautumn-sdk.d.ts
@@ -1,6 +1,8 @@
 // AUTO-GENERATED by atmn pull
 // DO NOT EDIT MANUALLY
 
+import type {} from "@useautumn/sdk";
+
 declare module '@useautumn/sdk' {
   // Features
   export const messages: Feature;
diff --git a/packages/atmn/src/commands/pull/sdkTypes.ts b/packages/atmn/src/commands/pull/sdkTypes.ts
index c876b87bc..32f71b65c 100644
--- a/packages/atmn/src/commands/pull/sdkTypes.ts
+++ b/packages/atmn/src/commands/pull/sdkTypes.ts
@@ -21,10 +21,14 @@ export async function generateSdkTypes(options: {
 	// Generate type definitions
 	const sections: string[] = [];
 
-	// Header
+	// Header -- top-level import makes this a module file,
+	// turning `declare module` into an augmentation instead of
+	// an ambient declaration that replaces the real module types.
 	sections.push(`// AUTO-GENERATED by atmn pull`);
 	sections.push(`// DO NOT EDIT MANUALLY`);
 	sections.push(``);
+	sections.push(`import type {} from "@useautumn/sdk";`);
+	sections.push(``);
 	sections.push(`declare module '@useautumn/sdk' {`);
 	sections.push(``);
 
diff --git a/packages/autumn-js/package.json b/packages/autumn-js/package.json
index a55ca89cf..59fee1969 100644
--- a/packages/autumn-js/package.json
+++ b/packages/autumn-js/package.json
@@ -1,7 +1,7 @@
 {
 	"name": "autumn-js",
 	"description": "Autumn JS Library",
-	"version": "1.1.2",
+	"version": "1.1.3",
 	"repository": "github:useautumn/autumn",
 	"homepage": "https://docs.useautumn.com",
 	"main": "./dist/sdk/index.js",