diff --git a/config/config.exs b/config/config.exs
index 08063cd..ffafd34 100644
--- a/config/config.exs
+++ b/config/config.exs
@@ -18,6 +18,8 @@ config :localiserd, Localiser.Web.Endpoint,
 config :localiserd, :jwt_secret,
   System.get_env("JWT_SECRET") || "localiser_dev_jwt_secret_change_in_prod!!"
 
+config :localiser, enrollment_timeout_ms: 10_000
+
 config :mdns_lite,
   hosts: ["localiser"],
   ttl: 120,
diff --git a/lib/localiser/domain/schema/sensor.ex b/lib/localiser/domain/schema/sensor.ex
index edc93ba..2c67468 100644
--- a/lib/localiser/domain/schema/sensor.ex
+++ b/lib/localiser/domain/schema/sensor.ex
@@ -7,6 +7,7 @@ defmodule Localiser.Domain.Schema.Sensor do
 
   schema "sensors" do
     field :sensor_id, :string
+    field :confirmed, :boolean, default: false
     field :x, :float
     field :y, :float
     field :floor_x, :float, virtual: true
@@ -21,7 +22,7 @@ defmodule Localiser.Domain.Schema.Sensor do
   @doc false
   def changeset(sensor, attrs) do
     sensor
-    |> cast(attrs, [:sensor_id, :room_id, :x, :y])
+    |> cast(attrs, [:sensor_id, :confirmed, :room_id, :x, :y])
     |> validate_required([:sensor_id])
     |> unique_constraint(:sensor_id)
     |> assoc_constraint(:room)
diff --git a/lib/localiser/domain/sensors.ex b/lib/localiser/domain/sensors.ex
index f37ef0a..faf404b 100644
--- a/lib/localiser/domain/sensors.ex
+++ b/lib/localiser/domain/sensors.ex
@@ -55,6 +55,8 @@ defmodule Localiser.Domain.Sensors do
   end
 
   def delete_sensor(%Sensor{} = sensor) do
+    topic = "localiser/sensor/#{sensor.sensor_id}/cmd"
+    Localiser.MQTT.Connection.publish(topic, Jason.encode!(%{command: "factory_reset"}))
     Repo.delete(sensor)
   end
 
@@ -89,14 +91,45 @@ defmodule Localiser.Domain.Sensors do
 
   # Sensor lifecycle / enrollment helpers
 
+  @enrollment_timeout_ms Application.compile_env(:localiser, :enrollment_timeout_ms, 10_000)
+
+  # Called by the phone app to indicate a sensor is about to come online.
+  # Creates an unconfirmed sensor record and starts a timeout Task.
+  def expect_sensor(sensor_id) do
+    result =
+      %Sensor{}
+      |> Sensor.changeset(%{sensor_id: sensor_id, confirmed: false})
+      |> Repo.insert(
+        on_conflict: [set: [confirmed: false, updated_at: DateTime.utc_now()]],
+        conflict_target: :sensor_id,
+        returning: true
+      )
+
+    case result do
+      {:ok, sensor} ->
+        Phoenix.PubSub.broadcast(Localiser.PubSub, "sensors", {:sensor_expected, sensor})
+        Task.start(fn ->
+          Process.sleep(@enrollment_timeout_ms)
+          fresh = Repo.get_by(Sensor, sensor_id: sensor_id)
+          if fresh && !fresh.confirmed do
+            Phoenix.PubSub.broadcast(Localiser.PubSub, "sensors", {:sensor_enrollment_timeout, sensor_id})
+          end
+        end)
+        {:ok, sensor}
+
+      error ->
+        error
+    end
+  end
+
   # Called when an ESP board self-announces on MQTT. Inserts a new unplaced sensor
-  # record, or bumps updated_at if the sensor_id already exists.
+  # record, or marks it confirmed if the sensor_id already exists.
   def upsert_announced(sensor_id) do
     result =
       %Sensor{}
-      |> Sensor.changeset(%{sensor_id: sensor_id})
+      |> Sensor.changeset(%{sensor_id: sensor_id, confirmed: true})
       |> Repo.insert(
-        on_conflict: [set: [updated_at: DateTime.utc_now()]],
+        on_conflict: [set: [confirmed: true, updated_at: DateTime.utc_now()]],
         conflict_target: :sensor_id,
         returning: true
       )
diff --git a/lib/localiser/web/channels/sensors_channel.ex b/lib/localiser/web/channels/sensors_channel.ex
index 719d33b..bf95146 100644
--- a/lib/localiser/web/channels/sensors_channel.ex
+++ b/lib/localiser/web/channels/sensors_channel.ex
@@ -28,6 +28,16 @@ defmodule Localiser.Web.Channels.SensorsChannel do
     {:noreply, socket}
   end
 
+  def handle_info({:sensor_expected, sensor}, socket) do
+    push(socket, "sensor_expected", render_sensor(sensor))
+    {:noreply, socket}
+  end
+
+  def handle_info({:sensor_enrollment_timeout, sensor_id}, socket) do
+    push(socket, "sensor_enrollment_timeout", %{sensor_id: sensor_id})
+    {:noreply, socket}
+  end
+
   def handle_info(_msg, socket), do: {:noreply, socket}
 
   defp render_sensor(sensor) do
diff --git a/lib/localiser/web/controllers/sensor_controller.ex b/lib/localiser/web/controllers/sensor_controller.ex
index a5034a0..723c65f 100644
--- a/lib/localiser/web/controllers/sensor_controller.ex
+++ b/lib/localiser/web/controllers/sensor_controller.ex
@@ -68,6 +68,15 @@ defmodule Localiser.Web.Controllers.SensorController do
       unauthorized: {"Unauthorized", "application/json", Schemas.Error}
     ]
 
+  operation :enroll,
+    summary: "Notify server a sensor is about to be enrolled",
+    request_body: {"Enroll params", "application/json", Schemas.SensorEnrollParams, required: true},
+    responses: [
+      ok: {"Sensor (unconfirmed)", "application/json", Schemas.Sensor},
+      bad_request: {"Missing sensor_id", "application/json", Schemas.Error},
+      unauthorized: {"Unauthorized", "application/json", Schemas.Error}
+    ]
+
   operation :calibration_start,
     summary: "Begin RSSI calibration",
     parameters: [id: [in: :path, type: :integer, required: true]],
@@ -86,6 +95,24 @@ defmodule Localiser.Web.Controllers.SensorController do
       unauthorized: {"Unauthorized", "application/json", Schemas.Error}
     ]
 
+  def enroll(conn, %{"sensor_id" => sensor_id}) do
+    case Sensors.expect_sensor(sensor_id) do
+      {:ok, sensor} ->
+        json(conn, render_sensor(sensor))
+
+      {:error, changeset} ->
+        conn
+        |> put_status(:unprocessable_entity)
+        |> json(%{errors: format_errors(changeset)})
+    end
+  end
+
+  def enroll(conn, _params) do
+    conn
+    |> put_status(:bad_request)
+    |> json(%{error: "sensor_id is required"})
+  end
+
   def index(conn, _params) do
     json(conn, Enum.map(Sensors.list_sensors(), &render_sensor/1))
   end
@@ -176,6 +203,7 @@ defmodule Localiser.Web.Controllers.SensorController do
     %{
       id:        sensor.id,
       sensor_id: sensor.sensor_id,
+      confirmed: sensor.confirmed,
       room_id:   sensor.room_id,
       floor_x:   sensor.floor_x,
       floor_y:   sensor.floor_y,
diff --git a/lib/localiser/web/router.ex b/lib/localiser/web/router.ex
index 30a7707..e1eb8d2 100644
--- a/lib/localiser/web/router.ex
+++ b/lib/localiser/web/router.ex
@@ -74,6 +74,7 @@ defmodule Localiser.Web.Router do
     resources "/tags", TagController, except: [:new, :edit]
 
     # Sensors
+    post   "/sensors",                         SensorController, :enroll
     get    "/sensors",                         SensorController, :index
     get    "/sensors/unplaced",                SensorController, :unplaced
     get    "/sensors/:id",                     SensorController, :show
diff --git a/lib/localiser/web/schemas.ex b/lib/localiser/web/schemas.ex
index ad44506..2fbb815 100644
--- a/lib/localiser/web/schemas.ex
+++ b/lib/localiser/web/schemas.ex
@@ -52,12 +52,13 @@ defmodule Localiser.Web.Schemas do
       properties: %{
         id:        %Schema{type: :integer},
         sensor_id: %Schema{type: :string},
+        confirmed: %Schema{type: :boolean},
         room_id:   %Schema{type: :integer, nullable: true},
         floor_x:   %Schema{type: :number, format: :float, nullable: true},
         floor_y:   %Schema{type: :number, format: :float, nullable: true},
         rssi_ref:  %Schema{type: :number, format: :float, nullable: true}
       },
-      required: [:id, :sensor_id]
+      required: [:id, :sensor_id, :confirmed]
     })
   end
 
@@ -236,6 +237,15 @@ defmodule Localiser.Web.Schemas do
     })
   end
 
+  defmodule SensorEnrollParams do
+    require OpenApiSpex
+    OpenApiSpex.schema(%{
+      title: "SensorEnrollParams", type: :object,
+      properties: %{sensor_id: %Schema{type: :string}},
+      required: [:sensor_id]
+    })
+  end
+
   defmodule SensorUpdateParams do
     require OpenApiSpex
     OpenApiSpex.schema(%{
diff --git a/priv/repo/migrations/20260515115837_add_confirmed_to_sensors.exs b/priv/repo/migrations/20260515115837_add_confirmed_to_sensors.exs
new file mode 100644
index 0000000..5c66fa8
--- /dev/null
+++ b/priv/repo/migrations/20260515115837_add_confirmed_to_sensors.exs
@@ -0,0 +1,9 @@
+defmodule Localiser.Repo.Migrations.AddConfirmedToSensors do
+  use Ecto.Migration
+
+  def change do
+    alter table(:sensors) do
+      add :confirmed, :boolean, default: false, null: false
+    end
+  end
+end