feat: accept calibration readings only from a chosen tag

lib/localiser/web/channels/calibration_channel.ex

@@ -23,6 +23,16 @@ defmodule Localiser.Web.Channels.CalibrationChannel do
     {:noreply, socket}
   end
 
+  def handle_info({:calibration_scan_reading, _sensor_id, tag_id, rssi}, socket) do
+    push(socket, "scan_reading", %{tag_id: tag_id, rssi: rssi})
+    {:noreply, socket}
+  end
+
+  def handle_info({:calibration_tag_set, _sensor_id, tag_id}, socket) do
+    push(socket, "tag_set", %{tag_id: tag_id})
+    {:noreply, socket}
+  end
+
   def handle_info({:stage_started, _sensor_id, distance, completed_count}, socket) do
     push(socket, "stage_started", %{distance: distance, completed_stages: completed_count})
     {:noreply, socket}

lib/localiser/web/controllers/sensor_controller.ex

@@ -116,6 +116,16 @@ defmodule Localiser.Web.Controllers.SensorController do
       unauthorized: {"Unauthorized", "application/json", Schemas.Error}
     ]
 
+  operation :calibration_set_tag,
+    summary: "Commit to a specific tag for calibration stages",
+    parameters: [id: [in: :path, type: :integer, required: true]],
+    request_body: {"Tag params", "application/json", Schemas.CalibrationTagParams, required: true},
+    responses: [
+      ok: {"Tag committed", "application/json", Schemas.CalibrationBeginResponse},
+      unprocessable_entity: {"Stage active or not in calibration mode", "application/json", Schemas.Error},
+      unauthorized: {"Unauthorized", "application/json", Schemas.Error}
+    ]
+
   operation :calibration_stage_start,
     summary: "Start collecting samples for a specific distance",
     parameters: [id: [in: :path, type: :integer, required: true]],
@@ -276,6 +286,31 @@ defmodule Localiser.Web.Controllers.SensorController do
     json(conn, %{status: "calibration_mode", samples_needed: calibration_samples_needed()})
   end
 
+  def calibration_set_tag(conn, %{"id" => id, "tag_id" => tag_id}) when is_binary(tag_id) do
+    sensor = Sensors.get_sensor!(id)
+
+    case SensorServer.set_calibration_tag(sensor.sensor_id, tag_id) do
+      :ok ->
+        json(conn, %{status: "calibration_mode", samples_needed: calibration_samples_needed()})
+
+      {:error, :stage_active} ->
+        conn
+        |> put_status(:unprocessable_entity)
+        |> json(%{error: "cannot change tag while a stage is active"})
+
+      {:error, :not_in_calibration_mode} ->
+        conn
+        |> put_status(:unprocessable_entity)
+        |> json(%{error: "sensor is not in calibration mode"})
+    end
+  end
+
+  def calibration_set_tag(conn, _params) do
+    conn
+    |> put_status(:bad_request)
+    |> json(%{error: "tag_id is required"})
+  end
+
   def calibration_stage_start(conn, %{"id" => id, "distance" => distance})
       when is_number(distance) and distance > 0 do
     sensor = Sensors.get_sensor!(id)
@@ -293,6 +328,11 @@ defmodule Localiser.Web.Controllers.SensorController do
         conn
         |> put_status(:unprocessable_entity)
         |> json(%{error: "sensor is not in calibration mode"})
+
+      {:error, :no_tag_selected} ->
+        conn
+        |> put_status(:unprocessable_entity)
+        |> json(%{error: "no tag selected — call /calibration/tag first"})
     end
   end
 

lib/localiser/web/router.ex

@@ -102,6 +102,7 @@ defmodule Localiser.Web.Router do
     post   "/sensors/:id/factory_reset",       SensorController, :factory_reset
     post   "/sensors/:id/reconfigure",         SensorController, :reconfigure
     post   "/sensors/:id/calibration/begin",   SensorController, :calibration_begin
+    post   "/sensors/:id/calibration/tag",     SensorController, :calibration_set_tag
     post   "/sensors/:id/calibration/stage",   SensorController, :calibration_stage_start
     post   "/sensors/:id/calibration/finish",  SensorController, :calibration_finish
     delete "/sensors/:id/calibration",         SensorController, :calibration_cancel

lib/localiser/web/schemas.ex

@@ -330,6 +330,17 @@ defmodule Localiser.Web.Schemas do
     })
   end
 
+  defmodule CalibrationTagParams do
+    require OpenApiSpex
+    OpenApiSpex.schema(%{
+      title: "CalibrationTagParams", type: :object,
+      properties: %{
+        tag_id: %Schema{type: :string, description: "Tag ID to lock in for calibration stages"}
+      },
+      required: [:tag_id]
+    })
+  end
+
   defmodule CalibrationStageParams do
     require OpenApiSpex
     OpenApiSpex.schema(%{