feat: Add optimized root devices GraphQL connection

Replaces the unpaginated manual relationship `devices` in `DeviceGroup`
with a scalable root `devices` connection that translates the group selector
into a native Ash.Expr database filter.

Updates Channel calculations (updatable_devices, deployable_devices,
download_capable_devices) to execute Postgres-level filters instead
of loading devices into memory, resolving OOM risks on huge groups.

Updates the frontend `DeviceGroup` component to query the root connection
and consume the standard `DevicesTable` component.

Signed-off-by: Davide Briani <davide.briani@secomind.com>

Author: davidebriani

backend/lib/edgehog/campaigns/channel/calculations/deployable_devices.ex

@@ -1,7 +1,7 @@
 #
 # This file is part of Edgehog.
 #
-# Copyright 2025 SECO Mind Srl
+# Copyright 2025-2026 SECO Mind Srl
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -28,10 +28,13 @@ defmodule Edgehog.Campaigns.Channel.Calculations.DeployableDevices do
   use Ash.Resource.Calculation
 
   alias Ash.Resource.Calculation
+  alias Edgehog.Selector
+
+  require Ash.Query
 
   @impl Calculation
   def load(_query, _opts, _context) do
-    [target_groups: [devices: :system_model]]
+    [target_groups: [:selector]]
   end
 
   @impl Calculation
@@ -43,22 +46,42 @@ defmodule Edgehog.Campaigns.Channel.Calculations.DeployableDevices do
       |> Ash.load!(:system_models)
       |> Map.get(:system_models, [])
 
-    Enum.map(deployment_channels, fn deployment_channel ->
-      deployment_channel.target_groups
-      |> Enum.flat_map(fn target_group ->
-        Enum.filter(
-          target_group.devices,
-          &satisfies?(&1.system_model, system_model_requirements)
-        )
-      end)
-      |> Enum.uniq_by(& &1.id)
-    end)
+    deployment_channels
+    |> Ash.load!(target_groups: [:selector])
+    |> Enum.map(&resolve_deployment_channel(&1, system_model_requirements, context))
+  end
+
+  defp resolve_deployment_channel(deployment_channel, system_model_requirements, context) do
+    combined_expr = Enum.reduce(deployment_channel.target_groups, nil, &combine_selectors/2)
+
+    if combined_expr do
+      query =
+        Edgehog.Devices.Device
+        |> Ash.Query.filter(^combined_expr)
+        |> Ash.Query.set_tenant(context.tenant)
+
+      query =
+        if system_model_requirements != [] do
+          system_model_ids = Enum.map(system_model_requirements, & &1.id)
+          Ash.Query.filter(query, system_model_part_number.system_model_id in ^system_model_ids)
+        else
+          query
+        end
+
+      Ash.read!(query)
+    else
+      []
+    end
   end
 
-  defp satisfies?(_system_model, [] = _system_model_requirements), do: true
-  defp satisfies?(nil = _system_model, _system_model_requirements), do: false
+  defp combine_selectors(group, acc) do
+    case Selector.parse(group.selector) do
+      {:ok, ast} ->
+        expr = Selector.to_ash_expr(ast)
+        if acc, do: Ash.Expr.expr(^expr or ^acc), else: expr
 
-  defp satisfies?(system_model, system_model_requirements) do
-    Enum.any?(system_model_requirements, &(system_model.id == &1.id))
+      _ ->
+        acc
+    end
   end
 end

backend/lib/edgehog/campaigns/channel/calculations/download_capable_devices.ex

@@ -22,16 +22,43 @@ defmodule Edgehog.Campaigns.Channel.Calculations.DownloadCapableDevices do
   @moduledoc false
   use Ash.Resource.Calculation
 
+  alias Edgehog.Selector
+
   require Ash.Query
 
   @impl Ash.Resource.Calculation
-  def calculate(channels, _opts, _context) do
+  def load(_query, _opts, _context) do
+    [target_groups: [:selector]]
+  end
+
+  @impl Ash.Resource.Calculation
+  def calculate(channels, _opts, context) do
     channels
-    |> Ash.load!(target_groups: [:devices])
-    |> Enum.map(fn channel ->
-      channel.target_groups
-      |> Enum.flat_map(& &1.devices)
-      |> Enum.uniq_by(& &1.id)
-    end)
+    |> Ash.load!(target_groups: [:selector])
+    |> Enum.map(&resolve_channel(&1, context))
+  end
+
+  defp resolve_channel(channel, context) do
+    combined_expr = Enum.reduce(channel.target_groups, nil, &combine_selectors/2)
+
+    if combined_expr do
+      Edgehog.Devices.Device
+      |> Ash.Query.filter(^combined_expr)
+      |> Ash.Query.set_tenant(context.tenant)
+      |> Ash.read!()
+    else
+      []
+    end
+  end
+
+  defp combine_selectors(group, acc) do
+    case Selector.parse(group.selector) do
+      {:ok, ast} ->
+        expr = Selector.to_ash_expr(ast)
+        if acc, do: Ash.Expr.expr(^expr or ^acc), else: expr
+
+      _ ->
+        acc
+    end
   end
 end

backend/lib/edgehog/campaigns/channel/calculations/updatable_devices.ex

@@ -1,7 +1,7 @@
 #
 # This file is part of Edgehog.
 #
-# Copyright 2024 SECO Mind Srl
+# Copyright 2024-2026 SECO Mind Srl
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -22,8 +22,15 @@ defmodule Edgehog.Campaigns.Channel.Calculations.UpdatableDevices do
   @moduledoc false
   use Ash.Resource.Calculation
 
+  alias Edgehog.Selector
+
   require Ash.Query
 
+  @impl Ash.Resource.Calculation
+  def load(_query, _opts, _context) do
+    [target_groups: [:selector]]
+  end
+
   @impl Ash.Resource.Calculation
   def calculate(channels, _opts, context) do
     %{arguments: %{base_image: base_image}} = context
@@ -33,16 +40,32 @@ defmodule Edgehog.Campaigns.Channel.Calculations.UpdatableDevices do
     system_model_id = base_image.base_image_collection.system_model_id
 
     channels
-    |> Ash.load!(target_groups: [devices: :system_model])
-    |> Enum.map(fn channel ->
-      channel.target_groups
-      |> Enum.flat_map(fn target_group ->
-        Enum.filter(
-          target_group.devices,
-          &(&1.system_model != nil && &1.system_model.id == system_model_id)
-        )
-      end)
-      |> Enum.uniq_by(& &1.id)
-    end)
+    |> Ash.load!(target_groups: [:selector])
+    |> Enum.map(&resolve_channel(&1, system_model_id, context))
+  end
+
+  defp resolve_channel(channel, system_model_id, context) do
+    combined_expr = Enum.reduce(channel.target_groups, nil, &combine_selectors/2)
+
+    if combined_expr do
+      Edgehog.Devices.Device
+      |> Ash.Query.filter(^combined_expr)
+      |> Ash.Query.filter(system_model_part_number.system_model_id == ^system_model_id)
+      |> Ash.Query.set_tenant(context.tenant)
+      |> Ash.read!()
+    else
+      []
+    end
+  end
+
+  defp combine_selectors(group, acc) do
+    case Selector.parse(group.selector) do
+      {:ok, ast} ->
+        expr = Selector.to_ash_expr(ast)
+        if acc, do: Ash.Expr.expr(^expr or ^acc), else: expr
+
+      _ ->
+        acc
+    end
   end
 end

backend/lib/edgehog/devices/device/device.ex

@@ -21,6 +21,7 @@
 defmodule Edgehog.Devices.Device do
   @moduledoc false
   use Edgehog.MultitenantResource,
+    primary_read_warning?: false,
     domain: Edgehog.Devices,
     extensions: [
       AshGraphql.Resource
@@ -75,7 +76,24 @@ defmodule Edgehog.Devices.Device do
   end
 
   actions do
-    defaults [:read, :destroy]
+    defaults [:destroy]
+
+    read :read do
+      primary? true
+      pagination keyset?: true, offset?: true, required?: false
+
+      argument :matching_group_id, :id do
+        description "Filters devices dynamically based on a DeviceGroup's selector"
+        allow_nil? true
+      end
+
+      argument :matching_selector, :string do
+        description "Optional raw selector for dry-runs"
+        allow_nil? true
+      end
+
+      prepare Edgehog.Devices.Device.Preparations.FilterBySelector
+    end
 
     create :create do
       primary? true
@@ -692,20 +710,21 @@ defmodule Edgehog.Devices.Device do
   end
 
   postgres do
-    table "devices"
-    repo Edgehog.Repo
+    table("devices")
+    repo(Edgehog.Repo)
 
     references do
-      reference :realm,
+      reference(:realm,
         index?: true,
         on_delete: :nothing,
         match_with: [tenant_id: :tenant_id],
         match_type: :full
+      )
 
       # We don't generate a foreign key for the system model part number since we want the device
       # to be able to declare its part number even _before_ we add the relative system model to
       # Edgehog
-      reference :system_model_part_number, ignore?: true
+      reference(:system_model_part_number, ignore?: true)
     end
   end
 end

backend/lib/edgehog/devices/device/preparations/filter_by_selector.ex

@@ -0,0 +1,63 @@
+#
+# This file is part of Edgehog.
+#
+# Copyright 2026 SECO Mind Srl
+#
+# 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
+#
+#    http://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.
+#
+# SPDX-License-Identifier: Apache-2.0
+#
+
+defmodule Edgehog.Devices.Device.Preparations.FilterBySelector do
+  @moduledoc false
+  use Ash.Resource.Preparation
+
+  alias Edgehog.Selector
+
+  require Ash.Query
+
+  @impl Ash.Resource.Preparation
+  def prepare(query, _opts, context) do
+    selector_string = get_selector(query, context)
+
+    if selector_string do
+      {:ok, ast} = Selector.parse(selector_string)
+      ash_expr = Selector.to_ash_expr(ast)
+      Ash.Query.filter(query, ^ash_expr)
+    else
+      query
+    end
+  end
+
+  defp get_selector(query, context) do
+    selector = Ash.Query.get_argument(query, :matching_selector)
+    group_id = Ash.Query.get_argument(query, :matching_group_id)
+
+    cond do
+      is_binary(selector) ->
+        selector
+
+      group_id != nil ->
+        group =
+          Edgehog.Groups.DeviceGroup
+          |> Ash.Query.filter(id == ^group_id)
+          |> Ash.Query.set_tenant(context.tenant)
+          |> Ash.read_first!()
+
+        if group, do: group.selector, else: nil
+
+      true ->
+        nil
+    end
+  end
+end