diff --git a/src/main/java/com/google/genai/gaos/hooks/SDKHooks.java b/src/main/java/com/google/genai/gaos/hooks/SDKHooks.java
index 0755b4ae4289..dbd4dac50ca8 100644
--- a/src/main/java/com/google/genai/gaos/hooks/SDKHooks.java
+++ b/src/main/java/com/google/genai/gaos/hooks/SDKHooks.java
@@ -37,11 +37,12 @@ private SDKHooks() {
     public static void initialize(com.google.genai.gaos.utils.Hooks hooks) {
         hooks.registerBeforeRequest(
             (context, request) -> {
+              HttpRequest.Builder builder = null;
               if (context.securitySource().isPresent()) {
                 HasSecurity hasSecurity = context.securitySource().get().getSecurity();
                 if (hasSecurity instanceof Security) {
                   Security security = (Security) hasSecurity;
-                  HttpRequest.Builder builder = request.toBuilder();
+                  builder = request.toBuilder();
 
                   if (security.defaultHeaders().isPresent()) {
                     for (Map.Entry<String, String> entry : security.defaultHeaders().get().entrySet()) {
@@ -53,21 +54,33 @@ public static void initialize(com.google.genai.gaos.utils.Hooks hooks) {
                   } else if (security.accessToken().isPresent()) {
                     builder.setHeader("Authorization", "Bearer " + security.accessToken().get());
                   }
-                  return builder.build();
                 }
               }
-              return request;
+              if (context.sdkConfiguration() != null
+                  && context.sdkConfiguration().globals != null
+                  && !request.headers().firstValue("x-goog-user-project").isPresent()) {
+                java.util.Optional<String> userProject =
+                    context.sdkConfiguration().globals.getParam("header", "x-goog-user-project");
+                if (userProject.isPresent()) {
+                  if (builder == null) {
+                    builder = request.toBuilder();
+                  }
+                  builder.setHeader("x-goog-user-project", userProject.get());
+                }
+              }
+              return builder != null ? builder.build() : request;
             });
     }
 
     public static void initialize(com.google.genai.gaos.utils.AsyncHooks asyncHooks) {
         asyncHooks.registerBeforeRequest(
             (context, request) -> {
+              HttpRequest.Builder builder = null;
               if (context.securitySource().isPresent()) {
                 HasSecurity hasSecurity = context.securitySource().get().getSecurity();
                 if (hasSecurity instanceof Security) {
                   Security security = (Security) hasSecurity;
-                  HttpRequest.Builder builder = request.toBuilder();
+                  builder = request.toBuilder();
 
                   if (security.defaultHeaders().isPresent()) {
                     for (Map.Entry<String, String> entry : security.defaultHeaders().get().entrySet()) {
@@ -79,10 +92,22 @@ public static void initialize(com.google.genai.gaos.utils.AsyncHooks asyncHooks)
                   } else if (security.accessToken().isPresent()) {
                     builder.setHeader("Authorization", "Bearer " + security.accessToken().get());
                   }
-                  return CompletableFuture.completedFuture(builder.build());
                 }
               }
-              return CompletableFuture.completedFuture(request);
+              if (context.sdkConfiguration() != null
+                  && context.sdkConfiguration().globals != null
+                  && !request.headers().firstValue("x-goog-user-project").isPresent()) {
+                java.util.Optional<String> userProject =
+                    context.sdkConfiguration().globals.getParam("header", "x-goog-user-project");
+                if (userProject.isPresent()) {
+                  if (builder == null) {
+                    builder = request.toBuilder();
+                  }
+                  builder.setHeader("x-goog-user-project", userProject.get());
+                }
+              }
+              return CompletableFuture.completedFuture(
+                  builder != null ? builder.build() : request);
             });
     }
 
diff --git a/src/test/java/com/google/genai/gaos/hooks/SDKHooksTest.java b/src/test/java/com/google/genai/gaos/hooks/SdkHooksTest.java
similarity index 72%
rename from src/test/java/com/google/genai/gaos/hooks/SDKHooksTest.java
rename to src/test/java/com/google/genai/gaos/hooks/SdkHooksTest.java
index 9d7280094c15..39455f7ab392 100644
--- a/src/test/java/com/google/genai/gaos/hooks/SDKHooksTest.java
+++ b/src/test/java/com/google/genai/gaos/hooks/SdkHooksTest.java
@@ -19,6 +19,7 @@
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertSame;
 
+import com.google.genai.gaos.SDKConfiguration;
 import com.google.genai.gaos.SecuritySource;
 import com.google.genai.gaos.models.shared.Security;
 import com.google.genai.gaos.utils.AsyncHooks;
@@ -32,11 +33,11 @@
 import org.junit.jupiter.api.Test;
 
 /**
- * Tests for {@link SDKHooks} to verify that request authorization headers
- * (x-goog-api-key, Authorization, defaultHeaders) are properly configured
- * and not accidentally cleared during SDK regeneration.
+ * Tests for {@link SDKHooks} to verify that request authorization headers (x-goog-api-key,
+ * Authorization, defaultHeaders) are properly configured and not accidentally cleared during SDK
+ * regeneration.
  */
-public final class SDKHooksTest {
+public final class SdkHooksTest {
 
   private static final String API_KEY = "test-api-key-12345";
   private static final String ACCESS_TOKEN = "test-access-token-abcde";
@@ -80,7 +81,8 @@ public void testSyncHookSetsAuthorizationHeader() throws Exception {
     HttpRequest request = createBaseRequest();
 
     HttpRequest modified = hooks.beforeRequest(context, request);
-    assertEquals("Bearer " + ACCESS_TOKEN, modified.headers().firstValue("Authorization").orElse(null));
+    assertEquals(
+        "Bearer " + ACCESS_TOKEN, modified.headers().firstValue("Authorization").orElse(null));
   }
 
   @Test
@@ -124,7 +126,8 @@ public void testAsyncHookSetsAuthorizationHeader() throws Exception {
     HttpRequest request = createBaseRequest();
 
     HttpRequest modified = asyncHooks.beforeRequest(context, request).get();
-    assertEquals("Bearer " + ACCESS_TOKEN, modified.headers().firstValue("Authorization").orElse(null));
+    assertEquals(
+        "Bearer " + ACCESS_TOKEN, modified.headers().firstValue("Authorization").orElse(null));
   }
 
   @Test
@@ -154,4 +157,41 @@ public void testHookWithoutSecurityPassesRequestThrough() throws Exception {
     HttpRequest modified = hooks.beforeRequest(context, request);
     assertSame(request, modified);
   }
+
+  @Test
+  public void testSyncAndAsyncHooksPropagateUserProjectFromGlobals() throws Exception {
+    Hooks hooks = new Hooks();
+    SDKHooks.initialize(hooks);
+    AsyncHooks asyncHooks = new AsyncHooks();
+    SDKHooks.initialize(asyncHooks);
+
+    SDKConfiguration config = new SDKConfiguration();
+    config.globals.putParam("header", "x-goog-user-project", "my-quota-project");
+    Hook.BeforeRequestContext context =
+        new Hook.BeforeRequestContextImpl(
+            config,
+            "https://generativelanguage.googleapis.com",
+            "createInteraction",
+            Optional.empty(),
+            Optional.empty());
+
+    HttpRequest request = createBaseRequest();
+    HttpRequest syncModified = hooks.beforeRequest(context, request);
+    assertEquals(
+        "my-quota-project", syncModified.headers().firstValue("x-goog-user-project").orElse(null));
+
+    HttpRequest asyncModified = asyncHooks.beforeRequest(context, request).get();
+    assertEquals(
+        "my-quota-project", asyncModified.headers().firstValue("x-goog-user-project").orElse(null));
+
+    // Existing x-goog-user-project header on the request should not be overwritten.
+    HttpRequest presetRequest =
+        request.toBuilder().setHeader("x-goog-user-project", "override-project").build();
+    HttpRequest syncPreset = hooks.beforeRequest(context, presetRequest);
+    assertEquals(
+        "override-project", syncPreset.headers().firstValue("x-goog-user-project").orElse(null));
+    HttpRequest asyncPreset = asyncHooks.beforeRequest(context, presetRequest).get();
+    assertEquals(
+        "override-project", asyncPreset.headers().firstValue("x-goog-user-project").orElse(null));
+  }
 }