feat: add switch control functionality to the Home Assistant integration

- Implemented TurnOn, TurnOff, and Toggle methods in the gRPC client for switch control.
- Added corresponding methods in the CommandApp to handle user commands for turning switches on, off, and toggling.
- Created unit tests for the new switch control methods in CommandApp and SwitchApp.
- Updated the HAGateway interface to include switch control methods.
- Enhanced the SwitchGRPC service to handle switch control requests and return appropriate responses.
- Added integration tests for the switch service to ensure correct behavior and error handling.

README.md

@@ -42,8 +42,8 @@ Internal gRPC gateway for Home Assistant.
 - Talks to Home Assistant through the REST API
 - Implements entity state lookup and discovery
 - Implements light control and light discovery
-- Implements switch discovery
+- Implements switch control and switch discovery
-- Stubs switch control and event streaming
+- Stubs event streaming
 - Supports optional mTLS when `TLS_DIR` is set
 - Exposes gRPC health checks and reflection
 
@@ -165,6 +165,9 @@ grpcurl -plaintext -d '{"domain":"light"}' \
 
 grpcurl -plaintext -d '{"entity_id":"light.living_room","brightness_pct":80}' \
   localhost:50051 ha.v1.LightService/TurnOn
+
+grpcurl -plaintext -d '{"entity_id":"switch.fan"}' \
+  localhost:50051 ha.v1.SwitchService/TurnOn
 ```
 
 With `ai-gateway` running locally:

discord-bot/README.md

@@ -35,10 +35,12 @@ AI-assisted commands.
 
 ```text
 /switch list
+/switch on switch:<entity>
+/switch off switch:<entity>
+/switch toggle switch:<entity>
 ```
 
-Switch control commands are not exposed yet. `ha-gateway` currently only
+- `switch` is required for action commands and uses autocomplete.
-implements switch discovery.
 
 ### AI
 
@@ -125,7 +127,6 @@ internal/telemetry/                      # OpenTelemetry setup
 
 ## Limitations
 
-- Switch commands are discovery-only.
 - The active AI model is not persisted.
 - The bot relies on Discord auth plus internal gateway/network controls; it
   does not implement per-user authorization.

discord-bot/internal/adapters/primary/discord/handler.go

@@ -26,6 +26,9 @@ type commandHandler interface {
 	HandleLightOff(ctx context.Context, entityID string, transition *uint32) (string, error)
 	HandleLightToggle(ctx context.Context, entityID string) (string, error)
 	HandleSwitchList(ctx context.Context) (string, error)
+	HandleSwitchOn(ctx context.Context, entityID string) (string, error)
+	HandleSwitchOff(ctx context.Context, entityID string) (string, error)
+	HandleSwitchToggle(ctx context.Context, entityID string) (string, error)
 	HandleAIQuery(ctx context.Context, text string) (string, error)
 	HandleAIModelSet(ctx context.Context, name string) (string, error)
 	HandleAIModelGet(ctx context.Context) (string, error)
@@ -159,6 +162,36 @@ func (h *Handler) handleApplicationCommand(ctx context.Context, s *discordgo.Ses
 		}
 		msg, err := h.app.HandleLightToggle(ctx, requiredStringOption(sub, "light"))
 		h.followup(ctx, s, i.Interaction, msg, true, start, err)
+	case "switch.on":
+		if err := h.deferResponse(s, i.Interaction, true); err != nil {
+			log.Error("discord response failed",
+				"duration_ms", time.Since(start).Milliseconds(),
+				"error", err.Error(),
+			)
+			return
+		}
+		msg, err := h.app.HandleSwitchOn(ctx, requiredStringOption(sub, "switch"))
+		h.followup(ctx, s, i.Interaction, msg, true, start, err)
+	case "switch.off":
+		if err := h.deferResponse(s, i.Interaction, true); err != nil {
+			log.Error("discord response failed",
+				"duration_ms", time.Since(start).Milliseconds(),
+				"error", err.Error(),
+			)
+			return
+		}
+		msg, err := h.app.HandleSwitchOff(ctx, requiredStringOption(sub, "switch"))
+		h.followup(ctx, s, i.Interaction, msg, true, start, err)
+	case "switch.toggle":
+		if err := h.deferResponse(s, i.Interaction, true); err != nil {
+			log.Error("discord response failed",
+				"duration_ms", time.Since(start).Milliseconds(),
+				"error", err.Error(),
+			)
+			return
+		}
+		msg, err := h.app.HandleSwitchToggle(ctx, requiredStringOption(sub, "switch"))
+		h.followup(ctx, s, i.Interaction, msg, true, start, err)
 	case "ai.query":
 		if err := h.deferResponse(s, i.Interaction, true); err != nil {
 			log.Error("discord response failed",

discord-bot/internal/adapters/primary/discord/register.go

@@ -72,13 +72,31 @@ func RegisterCommands(s *discordgo.Session, guildID string) error {
 		},
 		{
 			Name:        "switch",
-			Description: "Inspect switches",
+			Description: "Control and inspect switches",
 			Options: []*discordgo.ApplicationCommandOption{
 				{
 					Type:        discordgo.ApplicationCommandOptionSubCommand,
 					Name:        "list",
 					Description: "List switches",
 				},
+				{
+					Type:        discordgo.ApplicationCommandOptionSubCommand,
+					Name:        "on",
+					Description: "Turn on a switch",
+					Options:     []*discordgo.ApplicationCommandOption{switchOption()},
+				},
+				{
+					Type:        discordgo.ApplicationCommandOptionSubCommand,
+					Name:        "off",
+					Description: "Turn off a switch",
+					Options:     []*discordgo.ApplicationCommandOption{switchOption()},
+				},
+				{
+					Type:        discordgo.ApplicationCommandOptionSubCommand,
+					Name:        "toggle",
+					Description: "Toggle a switch",
+					Options:     []*discordgo.ApplicationCommandOption{switchOption()},
+				},
 			},
 		},
 		{
@@ -150,6 +168,17 @@ func lightOption() *discordgo.ApplicationCommandOption {
 	}
 }
 
+// switchOption centralizes the shared switch entity selector used by subcommands.
+func switchOption() *discordgo.ApplicationCommandOption {
+	return &discordgo.ApplicationCommandOption{
+		Type:         discordgo.ApplicationCommandOptionString,
+		Name:         "switch",
+		Description:  "Switch entity",
+		Required:     true,
+		Autocomplete: true,
+	}
+}
+
 // ptrFloat keeps command option min/max values readable in the command spec.
 func ptrFloat(v float64) *float64 {
 	return &v

discord-bot/internal/adapters/secondary/gateway/client.go

@@ -205,3 +205,48 @@ func (c *Client) ToggleLight(ctx context.Context, entityID string) error {
 	log.Debug("grpc call completed", "duration_ms", time.Since(start).Milliseconds())
 	return nil
 }
+
+// TurnOnSwitch forwards a switch turn-on request over gRPC.
+func (c *Client) TurnOnSwitch(ctx context.Context, entityID string) error {
+	start := time.Now()
+	log := logger.FromContext(ctx).With("grpc.method", "SwitchService/TurnOn")
+	if _, err := c.switchClient.TurnOn(ctx, &hav1.SwitchRequest{EntityId: entityID}); err != nil {
+		log.Error("grpc call failed",
+			"duration_ms", time.Since(start).Milliseconds(),
+			"error", err.Error(),
+		)
+		return fmt.Errorf("turn on switch %s: %w", entityID, err)
+	}
+	log.Debug("grpc call completed", "duration_ms", time.Since(start).Milliseconds())
+	return nil
+}
+
+// TurnOffSwitch forwards a switch turn-off request over gRPC.
+func (c *Client) TurnOffSwitch(ctx context.Context, entityID string) error {
+	start := time.Now()
+	log := logger.FromContext(ctx).With("grpc.method", "SwitchService/TurnOff")
+	if _, err := c.switchClient.TurnOff(ctx, &hav1.SwitchRequest{EntityId: entityID}); err != nil {
+		log.Error("grpc call failed",
+			"duration_ms", time.Since(start).Milliseconds(),
+			"error", err.Error(),
+		)
+		return fmt.Errorf("turn off switch %s: %w", entityID, err)
+	}
+	log.Debug("grpc call completed", "duration_ms", time.Since(start).Milliseconds())
+	return nil
+}
+
+// ToggleSwitch forwards a switch toggle request over gRPC.
+func (c *Client) ToggleSwitch(ctx context.Context, entityID string) error {
+	start := time.Now()
+	log := logger.FromContext(ctx).With("grpc.method", "SwitchService/Toggle")
+	if _, err := c.switchClient.Toggle(ctx, &hav1.SwitchRequest{EntityId: entityID}); err != nil {
+		log.Error("grpc call failed",
+			"duration_ms", time.Since(start).Milliseconds(),
+			"error", err.Error(),
+		)
+		return fmt.Errorf("toggle switch %s: %w", entityID, err)
+	}
+	log.Debug("grpc call completed", "duration_ms", time.Since(start).Milliseconds())
+	return nil
+}

discord-bot/internal/app/command.go

@@ -126,6 +126,42 @@ func (a *CommandApp) HandleSwitchList(ctx context.Context) (string, error) {
 	return strings.Join(lines, "\n"), nil
 }
 
+// HandleSwitchOn issues a turn-on request and returns a user-facing confirmation.
+func (a *CommandApp) HandleSwitchOn(ctx context.Context, entityID string) (string, error) {
+	name, err := a.lookupSwitchName(ctx, entityID)
+	if err != nil {
+		return "", fmt.Errorf("lookup switch name: %w", err)
+	}
+	if err := a.ha.TurnOnSwitch(ctx, entityID); err != nil {
+		return "", fmt.Errorf("handle switch on: %w", err)
+	}
+	return fmt.Sprintf("Turned on `%s`.", name), nil
+}
+
+// HandleSwitchOff issues a turn-off request and returns a user-facing confirmation.
+func (a *CommandApp) HandleSwitchOff(ctx context.Context, entityID string) (string, error) {
+	name, err := a.lookupSwitchName(ctx, entityID)
+	if err != nil {
+		return "", fmt.Errorf("lookup switch name: %w", err)
+	}
+	if err := a.ha.TurnOffSwitch(ctx, entityID); err != nil {
+		return "", fmt.Errorf("handle switch off: %w", err)
+	}
+	return fmt.Sprintf("Turned off `%s`.", name), nil
+}
+
+// HandleSwitchToggle issues a toggle request and returns a user-facing confirmation.
+func (a *CommandApp) HandleSwitchToggle(ctx context.Context, entityID string) (string, error) {
+	name, err := a.lookupSwitchName(ctx, entityID)
+	if err != nil {
+		return "", fmt.Errorf("lookup switch name: %w", err)
+	}
+	if err := a.ha.ToggleSwitch(ctx, entityID); err != nil {
+		return "", fmt.Errorf("handle switch toggle: %w", err)
+	}
+	return fmt.Sprintf("Toggled `%s`.", name), nil
+}
+
 // HandleAIQuery forwards a free-form request to ai-gateway.
 func (a *CommandApp) HandleAIQuery(ctx context.Context, text string) (string, error) {
 	reply, modelUsed, err := a.ai.Query(ctx, text, a.models.Get())
@@ -251,6 +287,25 @@ func (a *CommandApp) lookupLightName(ctx context.Context, entityID string) (stri
 	return lights[idx].FriendlyName, nil
 }
 
+// lookupSwitchName falls back to the entity ID so confirmations remain useful
+// even when Home Assistant does not expose a friendly name.
+func (a *CommandApp) lookupSwitchName(ctx context.Context, entityID string) (string, error) {
+	switches, err := a.ha.ListSwitches(ctx)
+	if err != nil {
+		return "", fmt.Errorf("list switches: %w", err)
+	}
+	idx := slices.IndexFunc(switches, func(sw driven.Switch) bool {
+		return sw.EntityID == entityID
+	})
+	if idx == -1 {
+		return entityID, nil
+	}
+	if switches[idx].FriendlyName == "" {
+		return entityID, nil
+	}
+	return switches[idx].FriendlyName, nil
+}
+
 // formatLightLine keeps list output compact because Discord code blocks are
 // easier to scan than rich embeds for dense discovery data.
 func formatLightLine(light driven.Light) string {

discord-bot/internal/app/command_test.go

@@ -15,9 +15,12 @@ import (
 type mockHAGateway struct {
 	listLightsFunc   func(ctx context.Context) ([]driven.Light, error)
 	listSwitchesFunc func(ctx context.Context) ([]driven.Switch, error)
-	turnOnLightFunc  func(ctx context.Context, entityID string, brightnessPct *uint32, colorTempKelvin *uint32) error
+	turnOnLightFunc   func(ctx context.Context, entityID string, brightnessPct *uint32, colorTempKelvin *uint32) error
-	turnOffLightFunc func(ctx context.Context, entityID string, transition *uint32) error
+	turnOffLightFunc  func(ctx context.Context, entityID string, transition *uint32) error
-	toggleLightFunc  func(ctx context.Context, entityID string) error
+	toggleLightFunc   func(ctx context.Context, entityID string) error
+	turnOnSwitchFunc  func(ctx context.Context, entityID string) error
+	turnOffSwitchFunc func(ctx context.Context, entityID string) error
+	toggleSwitchFunc  func(ctx context.Context, entityID string) error
 }
 
 type mockAIGateway struct {
@@ -60,6 +63,27 @@ func (m *mockHAGateway) ToggleLight(ctx context.Context, entityID string) error
 	return m.toggleLightFunc(ctx, entityID)
 }
 
+func (m *mockHAGateway) TurnOnSwitch(ctx context.Context, entityID string) error {
+	if m.turnOnSwitchFunc == nil {
+		return nil
+	}
+	return m.turnOnSwitchFunc(ctx, entityID)
+}
+
+func (m *mockHAGateway) TurnOffSwitch(ctx context.Context, entityID string) error {
+	if m.turnOffSwitchFunc == nil {
+		return nil
+	}
+	return m.turnOffSwitchFunc(ctx, entityID)
+}
+
+func (m *mockHAGateway) ToggleSwitch(ctx context.Context, entityID string) error {
+	if m.toggleSwitchFunc == nil {
+		return nil
+	}
+	return m.toggleSwitchFunc(ctx, entityID)
+}
+
 func (m *mockAIGateway) Query(ctx context.Context, text, model string) (string, string, error) {
 	if m.queryFunc == nil {
 		return "", "", nil
@@ -400,6 +424,183 @@ func TestCommandAppHandleSwitchList(t *testing.T) {
 	}
 }
 
+func TestCommandAppHandleSwitchOn(t *testing.T) {
+	tests := []struct {
+		name      string
+		switches  []driven.Switch
+		entityID  string
+		turnOnErr error
+		listErr   error
+		want      string
+		wantErr   string
+	}{
+		{
+			name:     "happy path",
+			switches: []driven.Switch{{EntityID: "switch.fan", FriendlyName: "Fan"}},
+			entityID: "switch.fan",
+			want:     "Turned on `Fan`.",
+		},
+		{
+			name:     "switch not found falls back to entity id",
+			switches: []driven.Switch{{EntityID: "switch.other", FriendlyName: "Other"}},
+			entityID: "switch.fan",
+			want:     "Turned on `switch.fan`.",
+		},
+		{
+			name:      "TurnOnSwitch error",
+			switches:  []driven.Switch{{EntityID: "switch.fan", FriendlyName: "Fan"}},
+			entityID:  "switch.fan",
+			turnOnErr: errors.New("boom"),
+			wantErr:   "handle switch on: boom",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			var gotEntityID string
+			app := newTestCommandApp(&mockHAGateway{
+				listSwitchesFunc: func(ctx context.Context) ([]driven.Switch, error) {
+					if tt.listErr != nil {
+						return nil, tt.listErr
+					}
+					return tt.switches, nil
+				},
+				turnOnSwitchFunc: func(ctx context.Context, entityID string) error {
+					gotEntityID = entityID
+					return tt.turnOnErr
+				},
+			}, &mockAIGateway{})
+
+			got, err := app.HandleSwitchOn(context.Background(), tt.entityID)
+			if tt.wantErr != "" {
+				if err == nil || err.Error() != tt.wantErr {
+					t.Fatalf("HandleSwitchOn() error = %v, want %q", err, tt.wantErr)
+				}
+				return
+			}
+			if err != nil {
+				t.Fatalf("HandleSwitchOn() error = %v", err)
+			}
+			if got != tt.want {
+				t.Fatalf("HandleSwitchOn() = %q, want %q", got, tt.want)
+			}
+			if gotEntityID != tt.entityID {
+				t.Fatalf("TurnOnSwitch entityID = %q, want %q", gotEntityID, tt.entityID)
+			}
+		})
+	}
+}
+
+func TestCommandAppHandleSwitchOff(t *testing.T) {
+	tests := []struct {
+		name       string
+		switches   []driven.Switch
+		entityID   string
+		turnOffErr error
+		want       string
+		wantErr    string
+	}{
+		{
+			name:     "happy path",
+			switches: []driven.Switch{{EntityID: "switch.fan", FriendlyName: "Fan"}},
+			entityID: "switch.fan",
+			want:     "Turned off `Fan`.",
+		},
+		{
+			name:       "TurnOffSwitch error",
+			switches:   []driven.Switch{{EntityID: "switch.fan", FriendlyName: "Fan"}},
+			entityID:   "switch.fan",
+			turnOffErr: errors.New("boom"),
+			wantErr:    "handle switch off: boom",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			app := newTestCommandApp(&mockHAGateway{
+				listSwitchesFunc: func(ctx context.Context) ([]driven.Switch, error) {
+					return tt.switches, nil
+				},
+				turnOffSwitchFunc: func(ctx context.Context, entityID string) error {
+					return tt.turnOffErr
+				},
+			}, &mockAIGateway{})
+
+			got, err := app.HandleSwitchOff(context.Background(), tt.entityID)
+			if tt.wantErr != "" {
+				if err == nil || err.Error() != tt.wantErr {
+					t.Fatalf("HandleSwitchOff() error = %v, want %q", err, tt.wantErr)
+				}
+				return
+			}
+			if err != nil {
+				t.Fatalf("HandleSwitchOff() error = %v", err)
+			}
+			if got != tt.want {
+				t.Fatalf("HandleSwitchOff() = %q, want %q", got, tt.want)
+			}
+		})
+	}
+}
+
+func TestCommandAppHandleSwitchToggle(t *testing.T) {
+	tests := []struct {
+		name      string
+		switches  []driven.Switch
+		listErr   error
+		toggleErr error
+		want      string
+		wantErr   string
+	}{
+		{
+			name:     "happy path",
+			switches: []driven.Switch{{EntityID: "switch.fan", FriendlyName: "Fan"}},
+			want:     "Toggled `Fan`.",
+		},
+		{
+			name:    "lookup error",
+			listErr: errors.New("lookup failed"),
+			wantErr: "lookup switch name: list switches: lookup failed",
+		},
+		{
+			name:      "toggle error",
+			switches:  []driven.Switch{{EntityID: "switch.fan", FriendlyName: "Fan"}},
+			toggleErr: errors.New("boom"),
+			wantErr:   "handle switch toggle: boom",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			app := newTestCommandApp(&mockHAGateway{
+				listSwitchesFunc: func(ctx context.Context) ([]driven.Switch, error) {
+					if tt.listErr != nil {
+						return nil, tt.listErr
+					}
+					return tt.switches, nil
+				},
+				toggleSwitchFunc: func(ctx context.Context, entityID string) error {
+					return tt.toggleErr
+				},
+			}, &mockAIGateway{})
+
+			got, err := app.HandleSwitchToggle(context.Background(), "switch.fan")
+			if tt.wantErr != "" {
+				if err == nil || err.Error() != tt.wantErr {
+					t.Fatalf("HandleSwitchToggle() error = %v, want %q", err, tt.wantErr)
+				}
+				return
+			}
+			if err != nil {
+				t.Fatalf("HandleSwitchToggle() error = %v", err)
+			}
+			if got != tt.want {
+				t.Fatalf("HandleSwitchToggle() = %q, want %q", got, tt.want)
+			}
+		})
+	}
+}
+
 func TestCommandAppAutocompleteLights(t *testing.T) {
 	tests := []struct {
 		name    string

discord-bot/internal/core/ports/driven/ha.go

@@ -13,6 +13,12 @@ type HAGateway interface {
 	TurnOffLight(ctx context.Context, entityID string, transition *uint32) error
 	// ToggleLight forwards a light toggle request to ha-gateway.
 	ToggleLight(ctx context.Context, entityID string) error
+	// TurnOnSwitch forwards a switch turn-on request to ha-gateway.
+	TurnOnSwitch(ctx context.Context, entityID string) error
+	// TurnOffSwitch forwards a switch turn-off request to ha-gateway.
+	TurnOffSwitch(ctx context.Context, entityID string) error
+	// ToggleSwitch forwards a switch toggle request to ha-gateway.
+	ToggleSwitch(ctx context.Context, entityID string) error
 }
 
 // Light is the discovery-oriented light view exposed by ha-gateway.

ha-gateway/README.md

@@ -25,13 +25,13 @@ Implemented:
 - `LightService.TurnOff`
 - `LightService.Toggle`
 - `LightService.ListLights`
+- `SwitchService.TurnOn`
+- `SwitchService.TurnOff`
+- `SwitchService.Toggle`
 - `SwitchService.ListSwitches`
 
 Stubbed:
 
-- `SwitchService.TurnOn`
-- `SwitchService.TurnOff`
-- `SwitchService.Toggle`
 - `EventService`
 
 The server also registers gRPC health checks and reflection.
@@ -122,7 +122,6 @@ internal/telemetry/                  # OpenTelemetry setup
 
 ## Limitations
 
-- Switch control RPCs return not implemented.
 - `EventService` is registered but not implemented.
 - Home Assistant WebSocket event streaming is still a TODO.
 - Keep this service internal or protect it with mTLS; it does not implement

ha-gateway/internal/adapters/primary/grpc/switch.go

@@ -4,6 +4,7 @@ import (
 	"context"
 
 	hav1 "gitea.nik4nao.com/nik/home-services/gen/ha/v1"
+	"gitea.nik4nao.com/nik/home-services/ha-gateway/internal/core/domain"
 	"gitea.nik4nao.com/nik/home-services/ha-gateway/internal/core/ports/driving"
 )
 
@@ -30,20 +31,29 @@ func (h *SwitchGRPC) ListSwitches(ctx context.Context, req *hav1.ListSwitchesReq
 	return &hav1.ListSwitchesResponse{Switches: out}, nil
 }
 
-// TurnOn is stubbed until switch control orchestration exists in the app layer.
+// TurnOn maps a protobuf turn-on request into a domain entity ID.
-// TODO: implement switch control RPCs — see plan.md for context
 func (h *SwitchGRPC) TurnOn(ctx context.Context, req *hav1.SwitchRequest) (*hav1.SwitchResponse, error) {
-	return nil, grpcError(ErrNotImplemented)
+	s, err := h.svc.TurnOn(ctx, domain.EntityID(req.EntityId))
+	if err != nil {
+		return nil, grpcError(err)
+	}
+	return &hav1.SwitchResponse{State: domainStateToProto(s)}, nil
 }
 
-// TurnOff is stubbed until switch control orchestration exists in the app layer.
+// TurnOff maps a protobuf turn-off request into a domain entity ID.
-// TODO: implement switch control RPCs — see plan.md for context
 func (h *SwitchGRPC) TurnOff(ctx context.Context, req *hav1.SwitchRequest) (*hav1.SwitchResponse, error) {
-	return nil, grpcError(ErrNotImplemented)
+	s, err := h.svc.TurnOff(ctx, domain.EntityID(req.EntityId))
+	if err != nil {
+		return nil, grpcError(err)
+	}
+	return &hav1.SwitchResponse{State: domainStateToProto(s)}, nil
 }
 
-// Toggle is stubbed until switch control orchestration exists in the app layer.
+// Toggle forwards a switch toggle request to the domain service.
-// TODO: implement switch control RPCs — see plan.md for context
 func (h *SwitchGRPC) Toggle(ctx context.Context, req *hav1.SwitchRequest) (*hav1.SwitchResponse, error) {
-	return nil, grpcError(ErrNotImplemented)
+	s, err := h.svc.Toggle(ctx, domain.EntityID(req.EntityId))
+	if err != nil {
+		return nil, grpcError(err)
+	}
+	return &hav1.SwitchResponse{State: domainStateToProto(s)}, nil
 }

ha-gateway/internal/adapters/primary/grpc/switch_test.go

@@ -0,0 +1,285 @@
+package grpc
+
+import (
+	"context"
+	"errors"
+	"net"
+	"testing"
+	"time"
+
+	hav1 "gitea.nik4nao.com/nik/home-services/gen/ha/v1"
+	"gitea.nik4nao.com/nik/home-services/ha-gateway/internal/core/domain"
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/credentials/insecure"
+	"google.golang.org/grpc/status"
+	"google.golang.org/grpc/test/bufconn"
+)
+
+type mockSwitchService struct {
+	turnOnFunc       func(ctx context.Context, id domain.EntityID) (*domain.EntityState, error)
+	turnOffFunc      func(ctx context.Context, id domain.EntityID) (*domain.EntityState, error)
+	toggleFunc       func(ctx context.Context, id domain.EntityID) (*domain.EntityState, error)
+	listSwitchesFunc func(ctx context.Context) ([]domain.Switch, error)
+	refreshFunc      func(ctx context.Context) error
+}
+
+func (m *mockSwitchService) TurnOn(ctx context.Context, id domain.EntityID) (*domain.EntityState, error) {
+	if m.turnOnFunc == nil {
+		return nil, nil
+	}
+	return m.turnOnFunc(ctx, id)
+}
+
+func (m *mockSwitchService) TurnOff(ctx context.Context, id domain.EntityID) (*domain.EntityState, error) {
+	if m.turnOffFunc == nil {
+		return nil, nil
+	}
+	return m.turnOffFunc(ctx, id)
+}
+
+func (m *mockSwitchService) Toggle(ctx context.Context, id domain.EntityID) (*domain.EntityState, error) {
+	if m.toggleFunc == nil {
+		return nil, nil
+	}
+	return m.toggleFunc(ctx, id)
+}
+
+func (m *mockSwitchService) ListSwitches(ctx context.Context) ([]domain.Switch, error) {
+	if m.listSwitchesFunc == nil {
+		return nil, nil
+	}
+	return m.listSwitchesFunc(ctx)
+}
+
+func (m *mockSwitchService) Refresh(ctx context.Context) error {
+	if m.refreshFunc == nil {
+		return nil
+	}
+	return m.refreshFunc(ctx)
+}
+
+func TestSwitchGRPCTurnOn(t *testing.T) {
+	now := time.Date(2026, 4, 9, 10, 0, 0, 0, time.UTC)
+
+	tests := []struct {
+		name     string
+		err      error
+		wantCode codes.Code
+	}{
+		{name: "happy path", wantCode: codes.OK},
+		{name: "not found maps to codes.NotFound", err: ErrNotFound, wantCode: codes.NotFound},
+		{name: "generic error maps to codes.Internal", err: errors.New("boom"), wantCode: codes.Internal},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			var gotID domain.EntityID
+			conn := newSwitchTestClientConn(t, &mockSwitchService{
+				turnOnFunc: func(ctx context.Context, id domain.EntityID) (*domain.EntityState, error) {
+					gotID = id
+					if tt.err != nil {
+						return nil, tt.err
+					}
+					return &domain.EntityState{
+						EntityID:    "switch.fan",
+						State:       "on",
+						Attributes:  map[string]string{"friendly_name": "Fan"},
+						LastChanged: now,
+						LastUpdated: now,
+					}, nil
+				},
+			})
+			client := hav1.NewSwitchServiceClient(conn)
+
+			resp, err := client.TurnOn(context.Background(), &hav1.SwitchRequest{EntityId: "switch.fan"})
+			if status.Code(err) != tt.wantCode {
+				t.Fatalf("status code = %v, want %v", status.Code(err), tt.wantCode)
+			}
+			if tt.wantCode != codes.OK {
+				return
+			}
+
+			if gotID != "switch.fan" {
+				t.Fatalf("TurnOn id = %q, want %q", gotID, "switch.fan")
+			}
+			if resp.GetState().GetEntityId() != "switch.fan" || resp.GetState().GetState() != "on" {
+				t.Fatalf("response state = %#v", resp.GetState())
+			}
+		})
+	}
+}
+
+func TestSwitchGRPCTurnOff(t *testing.T) {
+	now := time.Date(2026, 4, 9, 10, 0, 0, 0, time.UTC)
+
+	tests := []struct {
+		name     string
+		err      error
+		wantCode codes.Code
+	}{
+		{name: "happy path", wantCode: codes.OK},
+		{name: "error maps to codes.Internal", err: errors.New("boom"), wantCode: codes.Internal},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			var gotID domain.EntityID
+			conn := newSwitchTestClientConn(t, &mockSwitchService{
+				turnOffFunc: func(ctx context.Context, id domain.EntityID) (*domain.EntityState, error) {
+					gotID = id
+					if tt.err != nil {
+						return nil, tt.err
+					}
+					return &domain.EntityState{
+						EntityID:    "switch.fan",
+						State:       "off",
+						Attributes:  map[string]string{"friendly_name": "Fan"},
+						LastChanged: now,
+						LastUpdated: now,
+					}, nil
+				},
+			})
+			client := hav1.NewSwitchServiceClient(conn)
+
+			resp, err := client.TurnOff(context.Background(), &hav1.SwitchRequest{EntityId: "switch.fan"})
+			if status.Code(err) != tt.wantCode {
+				t.Fatalf("status code = %v, want %v", status.Code(err), tt.wantCode)
+			}
+			if tt.wantCode != codes.OK {
+				return
+			}
+
+			if gotID != "switch.fan" {
+				t.Fatalf("TurnOff id = %q, want %q", gotID, "switch.fan")
+			}
+			if resp.GetState().GetState() != "off" {
+				t.Fatalf("response state = %#v", resp.GetState())
+			}
+		})
+	}
+}
+
+func TestSwitchGRPCToggle(t *testing.T) {
+	now := time.Date(2026, 4, 9, 10, 0, 0, 0, time.UTC)
+
+	tests := []struct {
+		name     string
+		err      error
+		wantCode codes.Code
+	}{
+		{name: "happy path", wantCode: codes.OK},
+		{name: "not implemented maps to codes.Unimplemented", err: ErrNotImplemented, wantCode: codes.Unimplemented},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			var gotID domain.EntityID
+			conn := newSwitchTestClientConn(t, &mockSwitchService{
+				toggleFunc: func(ctx context.Context, id domain.EntityID) (*domain.EntityState, error) {
+					gotID = id
+					if tt.err != nil {
+						return nil, tt.err
+					}
+					return &domain.EntityState{
+						EntityID:    "switch.fan",
+						State:       "on",
+						Attributes:  map[string]string{"friendly_name": "Fan"},
+						LastChanged: now,
+						LastUpdated: now,
+					}, nil
+				},
+			})
+			client := hav1.NewSwitchServiceClient(conn)
+
+			resp, err := client.Toggle(context.Background(), &hav1.SwitchRequest{EntityId: "switch.fan"})
+			if status.Code(err) != tt.wantCode {
+				t.Fatalf("status code = %v, want %v", status.Code(err), tt.wantCode)
+			}
+			if tt.wantCode != codes.OK {
+				return
+			}
+
+			if gotID != "switch.fan" {
+				t.Fatalf("Toggle id = %q, want %q", gotID, "switch.fan")
+			}
+			if resp.GetState().GetEntityId() != "switch.fan" {
+				t.Fatalf("response state = %#v", resp.GetState())
+			}
+		})
+	}
+}
+
+func TestSwitchGRPCListSwitches(t *testing.T) {
+	tests := []struct {
+		name     string
+		err      error
+		wantCode codes.Code
+	}{
+		{name: "happy path with multiple switches", wantCode: codes.OK},
+		{name: "error path", err: errors.New("boom"), wantCode: codes.Internal},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			conn := newSwitchTestClientConn(t, &mockSwitchService{
+				listSwitchesFunc: func(ctx context.Context) ([]domain.Switch, error) {
+					if tt.err != nil {
+						return nil, tt.err
+					}
+					return []domain.Switch{
+						{EntityID: "switch.fan", FriendlyName: "Fan", State: "on", DeviceClass: "switch"},
+						{EntityID: "switch.heater", FriendlyName: "Heater", State: "off"},
+					}, nil
+				},
+			})
+			client := hav1.NewSwitchServiceClient(conn)
+
+			resp, err := client.ListSwitches(context.Background(), &hav1.ListSwitchesRequest{})
+			if status.Code(err) != tt.wantCode {
+				t.Fatalf("status code = %v, want %v", status.Code(err), tt.wantCode)
+			}
+			if tt.wantCode != codes.OK {
+				return
+			}
+
+			if len(resp.GetSwitches()) != 2 {
+				t.Fatalf("len(switches) = %d, want 2", len(resp.GetSwitches()))
+			}
+			if resp.GetSwitches()[0].GetEntityId() != "switch.fan" || resp.GetSwitches()[1].GetEntityId() != "switch.heater" {
+				t.Fatalf("switches = %#v", resp.GetSwitches())
+			}
+		})
+	}
+}
+
+func newSwitchTestClientConn(t *testing.T, svc *mockSwitchService) *grpc.ClientConn {
+	t.Helper()
+
+	lis := bufconn.Listen(testBufSize)
+	server := grpc.NewServer()
+	hav1.RegisterSwitchServiceServer(server, NewSwitchGRPC(svc))
+	go func() {
+		_ = server.Serve(lis)
+	}()
+	t.Cleanup(func() {
+		server.Stop()
+		_ = lis.Close()
+	})
+
+	conn, err := grpc.DialContext(
+		context.Background(),
+		"bufnet",
+		grpc.WithContextDialer(func(ctx context.Context, s string) (net.Conn, error) {
+			return lis.Dial()
+		}),
+		grpc.WithTransportCredentials(insecure.NewCredentials()),
+	)
+	if err != nil {
+		t.Fatalf("grpc.DialContext() error = %v", err)
+	}
+	t.Cleanup(func() {
+		_ = conn.Close()
+	})
+	return conn
+}

ha-gateway/internal/app/switch.go

@@ -57,6 +57,45 @@ func (a *SwitchApp) ListSwitches(ctx context.Context) ([]domain.Switch, error) {
 	return c, nil
 }
 
+// TurnOn maps application parameters into a Home Assistant switch.turn_on call.
+func (a *SwitchApp) TurnOn(ctx context.Context, id domain.EntityID) (*domain.EntityState, error) {
+	payload := map[string]any{"entity_id": string(id)}
+	return a.callService(ctx, "switch", "turn_on", payload)
+}
+
+// TurnOff maps application parameters into a Home Assistant switch.turn_off call.
+func (a *SwitchApp) TurnOff(ctx context.Context, id domain.EntityID) (*domain.EntityState, error) {
+	payload := map[string]any{"entity_id": string(id)}
+	return a.callService(ctx, "switch", "turn_off", payload)
+}
+
+// Toggle maps directly to Home Assistant switch.toggle.
+func (a *SwitchApp) Toggle(ctx context.Context, id domain.EntityID) (*domain.EntityState, error) {
+	payload := map[string]any{"entity_id": string(id)}
+	return a.callService(ctx, "switch", "toggle", payload)
+}
+
+// callService falls back to GetState because Home Assistant may succeed without
+// returning a full entity state list for the service call response.
+func (a *SwitchApp) callService(ctx context.Context, svcDomain, service string, payload map[string]any) (*domain.EntityState, error) {
+	states, err := a.ha.CallService(ctx, svcDomain, service, payload)
+	if err != nil {
+		return nil, err
+	}
+	entityID, _ := payload["entity_id"].(string)
+	for _, s := range states {
+		if s.EntityID == entityID {
+			return haStateToDomain(s), nil
+		}
+	}
+	// HA may return an empty list on success; fall back to GetState.
+	s, err := a.ha.GetState(ctx, entityID)
+	if err != nil {
+		return nil, err
+	}
+	return haStateToDomain(s), nil
+}
+
 // haStateToSwitch extracts the subset of attributes needed for switch discovery.
 func haStateToSwitch(s *driven.HAState) domain.Switch {
 	sw := domain.Switch{

ha-gateway/internal/app/switch_test.go

@@ -0,0 +1,297 @@
+package app
+
+import (
+	"context"
+	"errors"
+	"reflect"
+	"testing"
+	"time"
+
+	"gitea.nik4nao.com/nik/home-services/ha-gateway/internal/core/domain"
+	"gitea.nik4nao.com/nik/home-services/ha-gateway/internal/core/ports/driven"
+)
+
+func TestSwitchAppRefresh(t *testing.T) {
+	t.Run("filters non-switch entities and populates cache", func(t *testing.T) {
+		ha := &mockHAClient{
+			listStatesFunc: func(ctx context.Context) ([]*driven.HAState, error) {
+				return []*driven.HAState{
+					{
+						EntityID: "switch.fan",
+						State:    "on",
+						Attributes: map[string]any{
+							"friendly_name": "Fan",
+							"device_class":  "switch",
+						},
+					},
+					{
+						EntityID: "light.kitchen",
+						State:    "on",
+					},
+					{
+						EntityID: "switch.heater",
+						State:    "off",
+						Attributes: map[string]any{
+							"friendly_name": "Heater",
+						},
+					},
+				}, nil
+			},
+		}
+
+		app := NewSwitchApp(ha)
+		if err := app.Refresh(context.Background()); err != nil {
+			t.Fatalf("Refresh() error = %v", err)
+		}
+
+		got := app.cache
+		want := []domain.Switch{
+			{EntityID: "switch.fan", FriendlyName: "Fan", State: "on", DeviceClass: "switch"},
+			{EntityID: "switch.heater", FriendlyName: "Heater", State: "off"},
+		}
+		if !reflect.DeepEqual(got, want) {
+			t.Fatalf("cache = %#v, want %#v", got, want)
+		}
+	})
+}
+
+func TestSwitchAppListSwitches(t *testing.T) {
+	t.Run("uses cache when populated", func(t *testing.T) {
+		calls := 0
+		app := NewSwitchApp(&mockHAClient{
+			listStatesFunc: func(ctx context.Context) ([]*driven.HAState, error) {
+				calls++
+				return nil, nil
+			},
+		})
+		app.cache = []domain.Switch{{EntityID: "switch.fan", State: "on"}}
+
+		got, err := app.ListSwitches(context.Background())
+		if err != nil {
+			t.Fatalf("ListSwitches() error = %v", err)
+		}
+		if calls != 0 {
+			t.Fatalf("ListStates() calls = %d, want 0", calls)
+		}
+		if !reflect.DeepEqual(got, app.cache) {
+			t.Fatalf("ListSwitches() = %#v, want %#v", got, app.cache)
+		}
+	})
+
+	t.Run("calls ListStates when cache is nil", func(t *testing.T) {
+		calls := 0
+		app := NewSwitchApp(&mockHAClient{
+			listStatesFunc: func(ctx context.Context) ([]*driven.HAState, error) {
+				calls++
+				return []*driven.HAState{
+					{EntityID: "switch.fan", State: "on"},
+					{EntityID: "sensor.temp", State: "21"},
+				}, nil
+			},
+		})
+
+		got, err := app.ListSwitches(context.Background())
+		if err != nil {
+			t.Fatalf("ListSwitches() error = %v", err)
+		}
+		if calls != 1 {
+			t.Fatalf("ListStates() calls = %d, want 1", calls)
+		}
+		want := []domain.Switch{{EntityID: "switch.fan", State: "on"}}
+		if !reflect.DeepEqual(got, want) {
+			t.Fatalf("ListSwitches() = %#v, want %#v", got, want)
+		}
+	})
+
+	t.Run("propagates refresh error", func(t *testing.T) {
+		wantErr := errors.New("list failed")
+		app := NewSwitchApp(&mockHAClient{
+			listStatesFunc: func(ctx context.Context) ([]*driven.HAState, error) {
+				return nil, wantErr
+			},
+		})
+
+		_, err := app.ListSwitches(context.Background())
+		if !errors.Is(err, wantErr) {
+			t.Fatalf("ListSwitches() error = %v, want %v", err, wantErr)
+		}
+	})
+}
+
+func TestSwitchAppTurnOn(t *testing.T) {
+	now := time.Date(2026, 4, 9, 10, 0, 0, 0, time.UTC)
+	callState := &driven.HAState{
+		EntityID:    "switch.fan",
+		State:       "on",
+		Attributes:  map[string]any{"friendly_name": "Fan"},
+		LastChanged: now,
+		LastUpdated: now,
+	}
+	fallbackState := &driven.HAState{
+		EntityID:    "switch.fan",
+		State:       "on",
+		Attributes:  map[string]any{"friendly_name": "Fan", "source": "fallback"},
+		LastChanged: now,
+		LastUpdated: now,
+	}
+
+	t.Run("happy path", func(t *testing.T) {
+		app := NewSwitchApp(&mockHAClient{
+			callServiceFunc: func(ctx context.Context, svcDomain, service string, payload map[string]any) ([]*driven.HAState, error) {
+				if svcDomain != "switch" || service != "turn_on" {
+					t.Fatalf("CallService() domain/service = %s/%s", svcDomain, service)
+				}
+				wantPayload := map[string]any{"entity_id": "switch.fan"}
+				if !reflect.DeepEqual(payload, wantPayload) {
+					t.Fatalf("payload = %#v, want %#v", payload, wantPayload)
+				}
+				return []*driven.HAState{callState}, nil
+			},
+		})
+
+		got, err := app.TurnOn(context.Background(), "switch.fan")
+		if err != nil {
+			t.Fatalf("TurnOn() error = %v", err)
+		}
+		if !reflect.DeepEqual(got, haStateToDomain(callState)) {
+			t.Fatalf("TurnOn() = %#v, want %#v", got, haStateToDomain(callState))
+		}
+	})
+
+	t.Run("falls back to GetState when service returns empty list", func(t *testing.T) {
+		getStateCalls := 0
+		app := NewSwitchApp(&mockHAClient{
+			callServiceFunc: func(ctx context.Context, svcDomain, service string, payload map[string]any) ([]*driven.HAState, error) {
+				return []*driven.HAState{}, nil
+			},
+			getStateFunc: func(ctx context.Context, entityID string) (*driven.HAState, error) {
+				getStateCalls++
+				if entityID != "switch.fan" {
+					t.Fatalf("GetState() entityID = %q, want %q", entityID, "switch.fan")
+				}
+				return fallbackState, nil
+			},
+		})
+
+		got, err := app.TurnOn(context.Background(), "switch.fan")
+		if err != nil {
+			t.Fatalf("TurnOn() error = %v", err)
+		}
+		if getStateCalls != 1 {
+			t.Fatalf("GetState() calls = %d, want 1", getStateCalls)
+		}
+		if !reflect.DeepEqual(got, haStateToDomain(fallbackState)) {
+			t.Fatalf("TurnOn() = %#v, want %#v", got, haStateToDomain(fallbackState))
+		}
+	})
+
+	t.Run("returns CallService error", func(t *testing.T) {
+		wantErr := errors.New("call failed")
+		app := NewSwitchApp(&mockHAClient{
+			callServiceFunc: func(ctx context.Context, svcDomain, service string, payload map[string]any) ([]*driven.HAState, error) {
+				return nil, wantErr
+			},
+		})
+
+		_, err := app.TurnOn(context.Background(), "switch.fan")
+		if !errors.Is(err, wantErr) {
+			t.Fatalf("TurnOn() error = %v, want %v", err, wantErr)
+		}
+	})
+}
+
+func TestSwitchAppTurnOff(t *testing.T) {
+	now := time.Date(2026, 4, 9, 10, 0, 0, 0, time.UTC)
+	state := &driven.HAState{
+		EntityID:    "switch.fan",
+		State:       "off",
+		Attributes:  map[string]any{"friendly_name": "Fan"},
+		LastChanged: now,
+		LastUpdated: now,
+	}
+
+	t.Run("happy path", func(t *testing.T) {
+		app := NewSwitchApp(&mockHAClient{
+			callServiceFunc: func(ctx context.Context, svcDomain, service string, payload map[string]any) ([]*driven.HAState, error) {
+				if svcDomain != "switch" || service != "turn_off" {
+					t.Fatalf("CallService() domain/service = %s/%s", svcDomain, service)
+				}
+				wantPayload := map[string]any{"entity_id": "switch.fan"}
+				if !reflect.DeepEqual(payload, wantPayload) {
+					t.Fatalf("payload = %#v, want %#v", payload, wantPayload)
+				}
+				return []*driven.HAState{state}, nil
+			},
+		})
+
+		got, err := app.TurnOff(context.Background(), "switch.fan")
+		if err != nil {
+			t.Fatalf("TurnOff() error = %v", err)
+		}
+		if !reflect.DeepEqual(got, haStateToDomain(state)) {
+			t.Fatalf("TurnOff() = %#v, want %#v", got, haStateToDomain(state))
+		}
+	})
+
+	t.Run("error path", func(t *testing.T) {
+		wantErr := errors.New("turn off failed")
+		app := NewSwitchApp(&mockHAClient{
+			callServiceFunc: func(ctx context.Context, svcDomain, service string, payload map[string]any) ([]*driven.HAState, error) {
+				return nil, wantErr
+			},
+		})
+
+		_, err := app.TurnOff(context.Background(), "switch.fan")
+		if !errors.Is(err, wantErr) {
+			t.Fatalf("TurnOff() error = %v, want %v", err, wantErr)
+		}
+	})
+}
+
+func TestSwitchAppToggle(t *testing.T) {
+	now := time.Date(2026, 4, 9, 10, 0, 0, 0, time.UTC)
+	state := &driven.HAState{
+		EntityID:    "switch.fan",
+		State:       "on",
+		Attributes:  map[string]any{"friendly_name": "Fan"},
+		LastChanged: now,
+		LastUpdated: now,
+	}
+
+	t.Run("happy path", func(t *testing.T) {
+		app := NewSwitchApp(&mockHAClient{
+			callServiceFunc: func(ctx context.Context, svcDomain, service string, payload map[string]any) ([]*driven.HAState, error) {
+				if svcDomain != "switch" || service != "toggle" {
+					t.Fatalf("CallService() domain/service = %s/%s", svcDomain, service)
+				}
+				wantPayload := map[string]any{"entity_id": "switch.fan"}
+				if !reflect.DeepEqual(payload, wantPayload) {
+					t.Fatalf("payload = %#v, want %#v", payload, wantPayload)
+				}
+				return []*driven.HAState{state}, nil
+			},
+		})
+
+		got, err := app.Toggle(context.Background(), "switch.fan")
+		if err != nil {
+			t.Fatalf("Toggle() error = %v", err)
+		}
+		if !reflect.DeepEqual(got, haStateToDomain(state)) {
+			t.Fatalf("Toggle() = %#v, want %#v", got, haStateToDomain(state))
+		}
+	})
+
+	t.Run("error path", func(t *testing.T) {
+		wantErr := errors.New("toggle failed")
+		app := NewSwitchApp(&mockHAClient{
+			callServiceFunc: func(ctx context.Context, svcDomain, service string, payload map[string]any) ([]*driven.HAState, error) {
+				return nil, wantErr
+			},
+		})
+
+		_, err := app.Toggle(context.Background(), "switch.fan")
+		if !errors.Is(err, wantErr) {
+			t.Fatalf("Toggle() error = %v, want %v", err, wantErr)
+		}
+	})
+}

ha-gateway/internal/core/ports/driving/switch.go

@@ -7,6 +7,12 @@ import (
 )
 
 type SwitchService interface {
+	// TurnOn turns on a switch and returns the resulting entity state.
+	TurnOn(ctx context.Context, id domain.EntityID) (*domain.EntityState, error)
+	// TurnOff turns off a switch and returns the resulting entity state.
+	TurnOff(ctx context.Context, id domain.EntityID) (*domain.EntityState, error)
+	// Toggle toggles a switch and returns the resulting entity state.
+	Toggle(ctx context.Context, id domain.EntityID) (*domain.EntityState, error)
 	// ListSwitches returns cached switch metadata for discovery and UI use.
 	ListSwitches(ctx context.Context) ([]domain.Switch, error)
 	// Refresh repopulates the switch discovery cache from Home Assistant states.