diff --git a/lib/towerops/gaiia/actions.ex b/lib/towerops/gaiia/actions.ex
new file mode 100644
index 00000000..869721be
--- /dev/null
+++ b/lib/towerops/gaiia/actions.ex
@@ -0,0 +1,103 @@
+defmodule Towerops.Gaiia.Actions do
+  @moduledoc """
+  Write-back actions from Towerops to Gaiia.
+
+  Handles:
+  - Ticket creation from alerts
+  - Subscriber notes during outages
+  - Inventory item updates (IP, firmware, serial)
+  """
+
+  alias Towerops.Gaiia.Client
+  alias Towerops.Integrations
+
+  require Logger
+
+  @doc """
+  Create a Gaiia ticket for an alert.
+
+  Returns `{:ok, ticket_id}` on success, or `{:error, reason}`.
+  """
+  def create_ticket_for_alert(organization_id, alert) do
+    with {:ok, api_key} <- get_api_key(organization_id) do
+      subject = "Device Down: #{alert.device.name}"
+
+      description =
+        "Alert: #{alert.message}\nTriggered: #{DateTime.to_iso8601(alert.triggered_at)}"
+
+      variables = %{
+        "subject" => subject,
+        "description" => description
+      }
+
+      case Client.create_ticket(api_key, variables) do
+        {:ok, %{"createExternalTicket" => %{"id" => ticket_id}}} ->
+          {:ok, ticket_id}
+
+        {:error, reason} ->
+          Logger.warning("Failed to create Gaiia ticket for alert #{alert.id}: #{inspect(reason)}")
+          {:error, reason}
+      end
+    end
+  end
+
+  @doc """
+  Create a note on a Gaiia account (e.g., during an outage).
+
+  Returns `{:ok, note_id}` on success, or `{:error, reason}`.
+  """
+  def create_subscriber_note(organization_id, account_gaiia_id, content) do
+    with {:ok, api_key} <- get_api_key(organization_id) do
+      case Client.create_note(api_key, "ACCOUNT", account_gaiia_id, content) do
+        {:ok, %{"createNote" => %{"id" => note_id}}} ->
+          {:ok, note_id}
+
+        {:error, reason} ->
+          Logger.warning("Failed to create Gaiia note for account #{account_gaiia_id}: #{inspect(reason)}")
+
+          {:error, reason}
+      end
+    end
+  end
+
+  @doc """
+  Update a Gaiia inventory item with field changes.
+
+  Accepts a map of fields to update (e.g., `%{ip_address: "10.0.0.5"}`).
+  Returns `{:ok, data}` on success, or `{:error, reason}`.
+  """
+  def update_inventory_item(organization_id, item_gaiia_id, fields) do
+    with {:ok, api_key} <- get_api_key(organization_id) do
+      input = build_inventory_input(fields)
+
+      case Client.update_inventory_item(api_key, item_gaiia_id, input) do
+        {:ok, %{"updateInventoryItem" => data}} ->
+          {:ok, data}
+
+        {:error, reason} ->
+          Logger.warning("Failed to update Gaiia inventory item #{item_gaiia_id}: #{inspect(reason)}")
+
+          {:error, reason}
+      end
+    end
+  end
+
+  defp get_api_key(organization_id) do
+    case Integrations.get_integration(organization_id, "gaiia") do
+      {:ok, %{credentials: %{"api_key" => api_key}}} when is_binary(api_key) ->
+        {:ok, api_key}
+
+      _ ->
+        {:error, :no_integration}
+    end
+  end
+
+  defp build_inventory_input(fields) do
+    Enum.reduce(fields, %{}, fn
+      {:ip_address, value}, acc -> Map.put(acc, "ipAddress", value)
+      {:serial_number, value}, acc -> Map.put(acc, "serialNumber", value)
+      {:mac_address, value}, acc -> Map.put(acc, "macAddress", value)
+      {key, value}, acc -> Map.put(acc, to_string(key), value)
+    end)
+  end
+end
diff --git a/lib/towerops/gaiia/client.ex b/lib/towerops/gaiia/client.ex
index 40ae2eaa..1d469f13 100644
--- a/lib/towerops/gaiia/client.ex
+++ b/lib/towerops/gaiia/client.ex
@@ -141,6 +141,67 @@ defmodule Towerops.Gaiia.Client do
   }
   """
 
+  # --- Mutations ---
+
+  @create_ticket_mutation """
+  mutation CreateExternalTicket($subject: String!, $description: String!, $entityId: ID, $entityType: String) {
+    createExternalTicket(input: {
+      subject: $subject,
+      description: $description,
+      entityId: $entityId,
+      entityType: $entityType
+    }) {
+      id
+      subject
+    }
+  }
+  """
+
+  @create_note_mutation """
+  mutation CreateNote($entityId: ID!, $entityType: String!, $body: String!) {
+    createNote(input: {
+      entityId: $entityId,
+      entityType: $entityType,
+      body: $body
+    }) {
+      id
+    }
+  }
+  """
+
+  @update_inventory_item_mutation """
+  mutation UpdateInventoryItem($id: ID!, $input: UpdateInventoryItemInput!) {
+    updateInventoryItem(id: $id, input: $input) {
+      id
+      ipAddress
+      serialNumber
+    }
+  }
+  """
+
+  @doc "Create an external ticket in Gaiia."
+  def create_ticket(api_key, attrs, opts \\ []) do
+    query(api_key, @create_ticket_mutation, attrs, opts)
+  end
+
+  @doc "Create a note on a Gaiia entity (account, inventory item, etc)."
+  def create_note(api_key, entity_type, entity_id, body, opts \\ []) do
+    variables = %{
+      "entityId" => entity_id,
+      "entityType" => entity_type,
+      "body" => body
+    }
+
+    query(api_key, @create_note_mutation, variables, opts)
+  end
+
+  @doc "Update an inventory item in Gaiia."
+  def update_inventory_item(api_key, item_id, input, opts \\ []) do
+    query(api_key, @update_inventory_item_mutation, %{"id" => item_id, "input" => input}, opts)
+  end
+
+  # --- Queries ---
+
   @doc "Test the connection to Gaiia by running a simple viewer query."
   def test_connection(api_key, opts \\ []) do
     case query(api_key, "{ viewer { id } }", %{}, opts) do
diff --git a/test/towerops/gaiia/actions_test.exs b/test/towerops/gaiia/actions_test.exs
new file mode 100644
index 00000000..89403193
--- /dev/null
+++ b/test/towerops/gaiia/actions_test.exs
@@ -0,0 +1,127 @@
+defmodule Towerops.Gaiia.ActionsTest do
+  use Towerops.DataCase, async: true
+
+  import Towerops.AccountsFixtures
+  import Towerops.DevicesFixtures
+  import Towerops.OrganizationsFixtures
+
+  alias Towerops.Gaiia.Actions
+  alias Towerops.Gaiia.Client
+  alias Towerops.Integrations
+
+  setup do
+    user = user_fixture()
+    org = organization_fixture(user.id)
+
+    {:ok, integration} =
+      Integrations.create_integration(org.id, %{
+        provider: "gaiia",
+        enabled: true,
+        credentials: %{"api_key" => "test-key"}
+      })
+
+    %{org: org, integration: integration}
+  end
+
+  describe "create_ticket_for_alert/3" do
+    test "creates a ticket via Gaiia API and returns ticket ID", %{org: org} do
+      device = device_fixture(%{organization_id: org.id, name: "Tower Router"})
+
+      alert = %{
+        id: Ecto.UUID.generate(),
+        device: device,
+        alert_type: :device_down,
+        message: "Device is not responding to SNMP",
+        triggered_at: DateTime.utc_now()
+      }
+
+      Req.Test.stub(Client, fn conn ->
+        {:ok, body, conn} = Plug.Conn.read_body(conn)
+        decoded = Jason.decode!(body)
+        assert decoded["query"] =~ "createExternalTicket"
+
+        Req.Test.json(conn, %{
+          "data" => %{
+            "createExternalTicket" => %{
+              "id" => "gaiia-ticket-123",
+              "subject" => "Device Down: Tower Router"
+            }
+          }
+        })
+      end)
+
+      assert {:ok, "gaiia-ticket-123"} = Actions.create_ticket_for_alert(org.id, alert)
+    end
+
+    test "returns error when no integration exists" do
+      org_id = Ecto.UUID.generate()
+
+      alert = %{
+        id: Ecto.UUID.generate(),
+        alert_type: :device_down,
+        device: %{name: "Test"},
+        message: "Down",
+        triggered_at: DateTime.utc_now()
+      }
+
+      assert {:error, :no_integration} = Actions.create_ticket_for_alert(org_id, alert)
+    end
+  end
+
+  describe "create_subscriber_note/4" do
+    test "creates a note on a Gaiia account", %{org: org} do
+      Req.Test.stub(Client, fn conn ->
+        {:ok, body, conn} = Plug.Conn.read_body(conn)
+        decoded = Jason.decode!(body)
+        assert decoded["query"] =~ "createNote"
+
+        Req.Test.json(conn, %{
+          "data" => %{
+            "createNote" => %{
+              "id" => "gaiia-note-456"
+            }
+          }
+        })
+      end)
+
+      assert {:ok, "gaiia-note-456"} =
+               Actions.create_subscriber_note(org.id, "gaiia-acct-1", "Outage affecting Tower 3")
+    end
+
+    test "returns error when no integration exists" do
+      org_id = Ecto.UUID.generate()
+
+      assert {:error, :no_integration} =
+               Actions.create_subscriber_note(org_id, "gaiia-acct-1", "note")
+    end
+  end
+
+  describe "update_inventory_item/4" do
+    test "pushes field updates to Gaiia inventory item", %{org: org} do
+      Req.Test.stub(Client, fn conn ->
+        {:ok, body, conn} = Plug.Conn.read_body(conn)
+        decoded = Jason.decode!(body)
+        assert decoded["query"] =~ "updateInventoryItem"
+
+        Req.Test.json(conn, %{
+          "data" => %{
+            "updateInventoryItem" => %{
+              "id" => "gaiia-inv-1",
+              "ipAddress" => "10.0.0.5"
+            }
+          }
+        })
+      end)
+
+      assert {:ok, _data} =
+               Actions.update_inventory_item(org.id, "gaiia-inv-1", %{ip_address: "10.0.0.5"})
+    end
+
+    test "returns error when no integration exists" do
+      org_id = Ecto.UUID.generate()
+
+      assert {:error, :no_integration} =
+               Actions.update_inventory_item(org_id, "gaiia-inv-1", %{ip_address: "10.0.0.5"})
+    end
+  end
+end