diff --git a/proto/google/events/cloud/geminicloudassist/v1/data.proto b/proto/google/events/cloud/geminicloudassist/v1/data.proto
new file mode 100644
index 00000000..318dbe73
--- /dev/null
+++ b/proto/google/events/cloud/geminicloudassist/v1/data.proto
@@ -0,0 +1,29 @@
+// Copyright 2026 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+syntax = "proto3";
+
+package google.events.cloud.geminicloudassist.v1;
+
+option csharp_namespace = "Google.Events.Protobuf.Cloud.GeminiCloudAssist.V1";
+option php_namespace = "Google\\Events\\Cloud\\GeminiCloudAssist\\V1";
+option ruby_package = "Google::Events::Cloud::GeminiCloudAssist::V1";
+
+message TaskEventData {
+  // The resource name of the task being executed, e.g: investigation uri
+  string result_object_reference = 1;
+
+  // Human readable title of the task being executed
+  string title = 2;
+}
diff --git a/proto/google/events/cloud/geminicloudassist/v1/events.proto b/proto/google/events/cloud/geminicloudassist/v1/events.proto
new file mode 100644
index 00000000..1d3d305b
--- /dev/null
+++ b/proto/google/events/cloud/geminicloudassist/v1/events.proto
@@ -0,0 +1,39 @@
+// Copyright 2026 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+syntax = "proto3";
+
+package google.events.cloud.geminicloudassist.v1;
+
+import "google/events/cloud/geminicloudassist/v1/data.proto";
+import "google/events/cloudevent.proto";
+
+option csharp_namespace = "Google.Events.Protobuf.Cloud.GeminiCloudAssist.V1";
+option php_namespace = "Google\\Events\\Cloud\\GeminiCloudAssist\\V1";
+option ruby_package = "Google::Events::Cloud::GeminiCloudAssist::V1";
+option (google.events.cloud_event_product) = "Gemini Cloud Assist";
+option (google.events.cloud_event_extension_attribute) = {
+  name: "proactive"
+  description: "This field will be set to true if the task is executed proactively. Set to false in otherwise."
+  camel_case_name: "proactive"
+};
+
+message TaskCompletedEvent {
+  option (google.events.cloud_event_type) =
+      "google.cloud.geminicloudassist.task.v1.completed";
+  option (google.events.cloud_event_extension_name) = "proactive";
+
+  // The data associated with the event.
+  TaskEventData data = 1;
+}