diff --git a/test/towerops_web/graphql/resolvers/device_test.exs b/test/towerops_web/graphql/resolvers/device_test.exs
new file mode 100644
index 00000000..d6575aae
--- /dev/null
+++ b/test/towerops_web/graphql/resolvers/device_test.exs
@@ -0,0 +1,221 @@
+defmodule ToweropsWeb.GraphQL.Resolvers.DeviceTest do
+  use Towerops.DataCase, async: true
+
+  import Towerops.AccountsFixtures
+  import Towerops.DevicesFixtures
+  import Towerops.OrganizationsFixtures
+
+  alias ToweropsWeb.GraphQL.Resolvers.Device, as: Resolver
+
+  setup do
+    user = user_fixture()
+    org = organization_fixture(user.id)
+    other_user = user_fixture()
+    other_org = organization_fixture(other_user.id)
+
+    {:ok, site} = Towerops.Sites.create_site(%{name: "S1", organization_id: org.id})
+
+    %{
+      user: user,
+      org: org,
+      other_org: other_org,
+      site: site,
+      ctx: %{organization_id: org.id}
+    }
+  end
+
+  describe "list/3" do
+    test "returns devices for the org", %{org: org, site: site, ctx: ctx} do
+      _ =
+        device_fixture(%{
+          name: "Listed",
+          organization_id: org.id,
+          site_id: site.id
+        })
+
+      assert {:ok, devices} = Resolver.list(nil, %{}, %{context: ctx})
+      assert Enum.any?(devices, &(&1.name == "Listed"))
+    end
+
+    test "without context returns auth error" do
+      assert {:error, _} = Resolver.list(nil, %{}, %{})
+    end
+  end
+
+  describe "get/3" do
+    test "returns device with site preloaded", %{org: org, site: site, ctx: ctx} do
+      device =
+        device_fixture(%{name: "Found", organization_id: org.id, site_id: site.id})
+
+      assert {:ok, found} = Resolver.get(nil, %{id: device.id}, %{context: ctx})
+      assert found.id == device.id
+    end
+
+    test "returns 'not found' for cross-org id", %{other_org: other_org, ctx: ctx} do
+      foreign = device_fixture(%{organization_id: other_org.id})
+
+      assert {:error, "Device not found"} =
+               Resolver.get(nil, %{id: foreign.id}, %{context: ctx})
+    end
+
+    test "without context returns auth error" do
+      assert {:error, _} = Resolver.get(nil, %{id: Ecto.UUID.generate()}, %{})
+    end
+  end
+
+  describe "create/3, update/3, delete/3" do
+    test "creates a device under the org", %{site: site, ctx: ctx} do
+      assert {:ok, device} =
+               Resolver.create(
+                 nil,
+                 %{
+                   input: %{
+                     name: "Created",
+                     site_id: site.id,
+                     ip_address: "10.10.10.10"
+                   }
+                 },
+                 %{context: ctx}
+               )
+
+      assert device.name == "Created"
+      assert device.organization_id == ctx.organization_id
+    end
+
+    test "create returns formatted errors on invalid input", %{ctx: ctx} do
+      assert {:error, errors} =
+               Resolver.create(nil, %{input: %{name: ""}}, %{context: ctx})
+
+      assert is_list(errors) or is_binary(errors) or is_map(errors)
+    end
+
+    test "create without context returns auth error" do
+      assert {:error, _} = Resolver.create(nil, %{input: %{name: "x"}}, %{})
+    end
+
+    test "update + delete round-trip", %{org: org, site: site, ctx: ctx} do
+      device =
+        device_fixture(%{name: "Old", organization_id: org.id, site_id: site.id})
+
+      assert {:ok, updated} =
+               Resolver.update(nil, %{id: device.id, input: %{name: "New"}}, %{
+                 context: ctx
+               })
+
+      assert updated.name == "New"
+
+      assert {:ok, %{success: true}} =
+               Resolver.delete(nil, %{id: device.id}, %{context: ctx})
+    end
+
+    test "update on cross-org id returns 'not found'",
+         %{other_org: other_org, ctx: ctx} do
+      foreign = device_fixture(%{organization_id: other_org.id})
+
+      assert {:error, "Device not found"} =
+               Resolver.update(nil, %{id: foreign.id, input: %{name: "x"}}, %{
+                 context: ctx
+               })
+    end
+
+    test "update / delete without context returns auth errors" do
+      assert {:error, _} =
+               Resolver.update(nil, %{id: Ecto.UUID.generate(), input: %{}}, %{})
+
+      assert {:error, _} = Resolver.delete(nil, %{id: Ecto.UUID.generate()}, %{})
+    end
+  end
+
+  describe "metrics/3" do
+    test "returns [] for a device with no checks", %{org: org, site: site, ctx: ctx} do
+      device =
+        device_fixture(%{name: "NoChecks", organization_id: org.id, site_id: site.id})
+
+      assert {:ok, []} =
+               Resolver.metrics(
+                 nil,
+                 %{device_id: device.id, time_range: "24h"},
+                 %{context: ctx}
+               )
+    end
+
+    test "returns [] when device has a check but no results yet",
+         %{org: org, site: site, ctx: ctx} do
+      device =
+        device_fixture(%{name: "PendingMetric", organization_id: org.id, site_id: site.id})
+
+      {:ok, _check} =
+        Towerops.Monitoring.create_check(%{
+          name: "Inline Ping",
+          check_type: "ping",
+          device_id: device.id,
+          organization_id: org.id,
+          enabled: true,
+          interval_seconds: 60,
+          timeout_ms: 1000,
+          config: %{"host" => "127.0.0.1"}
+        })
+
+      assert {:ok, []} =
+               Resolver.metrics(
+                 nil,
+                 %{device_id: device.id, time_range: "24h"},
+                 %{context: ctx}
+               )
+    end
+
+    test "metrics without context returns auth error" do
+      assert {:error, _} =
+               Resolver.metrics(nil, %{device_id: Ecto.UUID.generate()}, %{})
+    end
+
+    test "metrics on cross-org id returns 'not found'",
+         %{other_org: other_org, ctx: ctx} do
+      foreign = device_fixture(%{organization_id: other_org.id})
+
+      assert {:error, "Device not found"} =
+               Resolver.metrics(
+                 nil,
+                 %{device_id: foreign.id, time_range: "1h"},
+                 %{context: ctx}
+               )
+    end
+
+    test "metrics falls back to 24h when time_range is unparseable",
+         %{org: org, site: site, ctx: ctx} do
+      device =
+        device_fixture(%{name: "Fallback", organization_id: org.id, site_id: site.id})
+
+      assert {:ok, _} =
+               Resolver.metrics(
+                 nil,
+                 %{device_id: device.id, time_range: "garbage"},
+                 %{context: ctx}
+               )
+    end
+  end
+
+  describe "interfaces/3" do
+    test "returns [] when device has no snmp_device",
+         %{org: org, site: site, ctx: ctx} do
+      device =
+        device_fixture(%{name: "NoSnmp", organization_id: org.id, site_id: site.id})
+
+      assert {:ok, []} =
+               Resolver.interfaces(nil, %{device_id: device.id}, %{context: ctx})
+    end
+
+    test "interfaces returns 'not found' for cross-org id",
+         %{other_org: other_org, ctx: ctx} do
+      foreign = device_fixture(%{organization_id: other_org.id})
+
+      assert {:error, "Device not found"} =
+               Resolver.interfaces(nil, %{device_id: foreign.id}, %{context: ctx})
+    end
+
+    test "interfaces without context returns auth error" do
+      assert {:error, _} =
+               Resolver.interfaces(nil, %{device_id: Ecto.UUID.generate()}, %{})
+    end
+  end
+end
diff --git a/test/towerops_web/graphql/resolvers/schedule_test.exs b/test/towerops_web/graphql/resolvers/schedule_test.exs
new file mode 100644
index 00000000..b89a021a
--- /dev/null
+++ b/test/towerops_web/graphql/resolvers/schedule_test.exs
@@ -0,0 +1,262 @@
+defmodule ToweropsWeb.GraphQL.Resolvers.ScheduleTest do
+  use Towerops.DataCase, async: true
+
+  import Towerops.AccountsFixtures
+  import Towerops.OnCallFixtures
+  import Towerops.OrganizationsFixtures
+
+  alias ToweropsWeb.GraphQL.Resolvers.Schedule, as: Resolver
+
+  setup do
+    user = user_fixture()
+    org = organization_fixture(user.id)
+    other_user = user_fixture()
+    other_org = organization_fixture(other_user.id)
+
+    %{user: user, org: org, other_org: other_org, ctx: %{organization_id: org.id}}
+  end
+
+  describe "list/3" do
+    test "returns schedules for the org", %{org: org, ctx: ctx} do
+      _ = schedule_fixture(org.id, %{name: "Primary Schedule"})
+
+      assert {:ok, schedules} = Resolver.list(nil, %{}, %{context: ctx})
+      assert Enum.any?(schedules, &(&1.name == "Primary Schedule"))
+    end
+
+    test "without org context returns auth error" do
+      assert {:error, _} = Resolver.list(nil, %{}, %{})
+    end
+  end
+
+  describe "get/3" do
+    test "returns the schedule preloaded with overrides + layers", %{org: org, ctx: ctx} do
+      schedule = schedule_fixture(org.id)
+
+      assert {:ok, found} = Resolver.get(nil, %{id: schedule.id}, %{context: ctx})
+      assert found.id == schedule.id
+    end
+
+    test "returns 'not found' for cross-org id", %{other_org: other_org, ctx: ctx} do
+      foreign = schedule_fixture(other_org.id)
+
+      assert {:error, "Schedule not found"} =
+               Resolver.get(nil, %{id: foreign.id}, %{context: ctx})
+    end
+
+    test "without org context returns auth error" do
+      assert {:error, _} = Resolver.get(nil, %{id: Ecto.UUID.generate()}, %{})
+    end
+  end
+
+  describe "on_call/3" do
+    test "returns nil when no one is on call (empty schedule)", %{org: org, ctx: ctx} do
+      schedule = schedule_fixture(org.id)
+      assert {:ok, nil} = Resolver.on_call(nil, %{schedule_id: schedule.id}, %{context: ctx})
+    end
+
+    test "returns 'not found' for cross-org id", %{other_org: other_org, ctx: ctx} do
+      foreign = schedule_fixture(other_org.id)
+
+      assert {:error, "Schedule not found"} =
+               Resolver.on_call(nil, %{schedule_id: foreign.id}, %{context: ctx})
+    end
+
+    test "without org context returns auth error" do
+      assert {:error, _} =
+               Resolver.on_call(nil, %{schedule_id: Ecto.UUID.generate()}, %{})
+    end
+  end
+
+  describe "create/3, update/3, delete/3" do
+    test "creates a schedule scoped to the resolved org", %{ctx: ctx} do
+      assert {:ok, schedule} =
+               Resolver.create(nil, %{input: %{name: "Created", timezone: "UTC"}}, %{
+                 context: ctx
+               })
+
+      assert schedule.name == "Created"
+      assert schedule.organization_id == ctx.organization_id
+    end
+
+    test "create returns formatted errors on invalid input", %{ctx: ctx} do
+      assert {:error, errors} =
+               Resolver.create(nil, %{input: %{name: ""}}, %{context: ctx})
+
+      assert is_list(errors) or is_binary(errors) or is_map(errors)
+    end
+
+    test "create without org context returns auth error" do
+      assert {:error, _} = Resolver.create(nil, %{input: %{name: "x"}}, %{})
+    end
+
+    test "update + delete round-trip", %{org: org, ctx: ctx} do
+      schedule = schedule_fixture(org.id, %{name: "Original"})
+
+      assert {:ok, updated} =
+               Resolver.update(nil, %{id: schedule.id, input: %{name: "Renamed"}}, %{
+                 context: ctx
+               })
+
+      assert updated.name == "Renamed"
+
+      assert {:ok, %{success: true}} =
+               Resolver.delete(nil, %{id: schedule.id}, %{context: ctx})
+    end
+
+    test "update on cross-org id returns 'not found'",
+         %{other_org: other_org, ctx: ctx} do
+      foreign = schedule_fixture(other_org.id)
+
+      assert {:error, "Schedule not found"} =
+               Resolver.update(nil, %{id: foreign.id, input: %{name: "x"}}, %{context: ctx})
+    end
+
+    test "update / delete / create without context returns auth errors" do
+      assert {:error, _} =
+               Resolver.update(nil, %{id: Ecto.UUID.generate(), input: %{}}, %{})
+
+      assert {:error, _} = Resolver.delete(nil, %{id: Ecto.UUID.generate()}, %{})
+    end
+  end
+
+  describe "layer mutations" do
+    test "create_layer attaches a layer to a schedule", %{org: org, ctx: ctx} do
+      schedule = schedule_fixture(org.id)
+
+      assert {:ok, layer} =
+               Resolver.create_layer(
+                 nil,
+                 %{
+                   schedule_id: schedule.id,
+                   input: %{
+                     name: "Primary",
+                     position: 1,
+                     rotation_type: "weekly",
+                     rotation_interval: 1,
+                     handoff_time: ~T[09:00:00],
+                     handoff_day: 1,
+                     start_date: ~U[2026-01-01 09:00:00Z]
+                   }
+                 },
+                 %{context: ctx}
+               )
+
+      assert layer.schedule_id == schedule.id
+    end
+
+    test "create_layer auth error without context" do
+      assert {:error, _} =
+               Resolver.create_layer(
+                 nil,
+                 %{schedule_id: Ecto.UUID.generate(), input: %{}},
+                 %{}
+               )
+    end
+
+    test "update_layer + delete_layer round-trip", %{org: org, ctx: ctx} do
+      schedule = schedule_fixture(org.id)
+      layer = layer_fixture(schedule.id, %{name: "Old"})
+
+      assert {:ok, updated} =
+               Resolver.update_layer(nil, %{id: layer.id, input: %{name: "New"}}, %{
+                 context: ctx
+               })
+
+      assert updated.name == "New"
+
+      assert {:ok, %{success: true}} =
+               Resolver.delete_layer(nil, %{id: layer.id}, %{context: ctx})
+    end
+
+    test "update_layer on missing layer returns 'not found'", %{ctx: ctx} do
+      assert {:error, "Layer not found"} =
+               Resolver.update_layer(nil, %{id: Ecto.UUID.generate(), input: %{}}, %{
+                 context: ctx
+               })
+    end
+
+    test "update_layer auth error without context" do
+      assert {:error, _} =
+               Resolver.update_layer(nil, %{id: Ecto.UUID.generate(), input: %{}}, %{})
+    end
+
+    test "delete_layer auth error without context" do
+      assert {:error, _} =
+               Resolver.delete_layer(nil, %{id: Ecto.UUID.generate()}, %{})
+    end
+  end
+
+  describe "member mutations" do
+    test "add_member + remove_member round-trip", %{org: org, user: user, ctx: ctx} do
+      schedule = schedule_fixture(org.id)
+      layer = layer_fixture(schedule.id)
+
+      assert {:ok, member} =
+               Resolver.add_member(
+                 nil,
+                 %{layer_id: layer.id, user_id: user.id, position: 0},
+                 %{context: ctx}
+               )
+
+      assert {:ok, %{success: true}} =
+               Resolver.remove_member(nil, %{id: member.id}, %{context: ctx})
+    end
+
+    test "remove_member returns 'not found' for unknown id", %{ctx: ctx} do
+      assert {:error, "Member not found"} =
+               Resolver.remove_member(nil, %{id: Ecto.UUID.generate()}, %{context: ctx})
+    end
+
+    test "add_member + remove_member auth errors without context" do
+      assert {:error, _} =
+               Resolver.add_member(
+                 nil,
+                 %{layer_id: Ecto.UUID.generate(), user_id: Ecto.UUID.generate(), position: 0},
+                 %{}
+               )
+
+      assert {:error, _} = Resolver.remove_member(nil, %{id: Ecto.UUID.generate()}, %{})
+    end
+  end
+
+  describe "override mutations" do
+    test "create_override + delete_override round-trip",
+         %{org: org, user: user, ctx: ctx} do
+      schedule = schedule_fixture(org.id)
+
+      assert {:ok, override} =
+               Resolver.create_override(
+                 nil,
+                 %{
+                   schedule_id: schedule.id,
+                   input: %{
+                     user_id: user.id,
+                     start_time: ~U[2026-04-01 09:00:00Z],
+                     end_time: ~U[2026-04-02 09:00:00Z]
+                   }
+                 },
+                 %{context: ctx}
+               )
+
+      assert {:ok, %{success: true}} =
+               Resolver.delete_override(nil, %{id: override.id}, %{context: ctx})
+    end
+
+    test "delete_override returns 'not found' for unknown id", %{ctx: ctx} do
+      assert {:error, "Override not found"} =
+               Resolver.delete_override(nil, %{id: Ecto.UUID.generate()}, %{context: ctx})
+    end
+
+    test "create_override + delete_override auth errors without context" do
+      assert {:error, _} =
+               Resolver.create_override(
+                 nil,
+                 %{schedule_id: Ecto.UUID.generate(), input: %{}},
+                 %{}
+               )
+
+      assert {:error, _} = Resolver.delete_override(nil, %{id: Ecto.UUID.generate()}, %{})
+    end
+  end
+end