diff --git a/README.md b/README.md
index e69de29..90fa31c 100644
--- a/README.md
+++ b/README.md
@@ -0,0 +1,185 @@
+# home-service
+
+This workspace contains a Home Assistant gRPC gateway and the protobuf contract
+it serves.
+
+The current implementation is centered on `ha-gateway`, a Go service that:
+
+- exposes Home Assistant operations over gRPC
+- translates gRPC requests into Home Assistant REST API calls
+- emits OpenTelemetry traces and metrics when configured
+- keeps protobuf definitions and generated Go stubs in-repo
+
+`EntityService` and `LightService` are implemented. `SwitchService` and
+`EventService` are scaffolded but currently return `Unimplemented`.
+
+## Workspace Layout
+
+```text
+.
+├── proto/                 # Source protobuf definitions
+├── gen/                   # Generated Go protobuf/grpc code (committed)
+├── ha-gateway/            # Go gRPC server
+├── buf.yaml               # Buf module config
+├── buf.gen.yaml           # Buf codegen config
+└── go.work                # Go workspace linking gen + ha-gateway
+```
+
+## Architecture
+
+`ha-gateway` follows a ports-and-adapters structure:
+
+- `internal/core/domain`: pure domain types
+- `internal/core/ports/driving`: interfaces exposed to primary adapters
+- `internal/core/ports/driven`: interfaces the app layer depends on
+- `internal/app`: application logic for entity and light operations
+- `internal/adapters/primary/grpc`: gRPC handlers and proto/domain mapping
+- `internal/adapters/secondary/ha`: Home Assistant REST client
+- `internal/telemetry`: OpenTelemetry setup
+
+The runtime flow is:
+
+1. A gRPC client calls `EntityService` or `LightService`.
+2. The gRPC adapter maps protobuf messages into domain parameters.
+3. The app layer orchestrates the use case.
+4. The HA adapter calls Home Assistant's REST API.
+5. The response is mapped back into the protobuf response.
+
+## Services
+
+### Implemented
+
+- `ha.v1.EntityService`
+  - `GetState`
+  - `ListStates`
+- `ha.v1.LightService`
+  - `TurnOn`
+  - `TurnOff`
+  - `Toggle`
+
+### Stubbed
+
+- `ha.v1.SwitchService`
+- `ha.v1.EventService`
+
+The event path is planned around Home Assistant WebSocket subscriptions, but the
+WebSocket adapter and fan-out broker are not implemented yet.
+
+## Configuration
+
+`ha-gateway` reads configuration from environment variables. A sample file lives
+at [ha-gateway/.env.example](/Users/nik-macbookair/repo/home-service/ha-gateway/.env.example).
+
+| Variable | Required | Default | Notes |
+| --- | --- | --- | --- |
+| `HA_TOKEN` | yes | none | Home Assistant long-lived access token |
+| `GRPC_PORT` | no | `50051` | gRPC listen port |
+| `HA_BASE_URL` | effectively yes | empty | Example: `http://ha.home.arpa:8123` |
+| `OTEL_ENDPOINT` | no | empty | OTLP gRPC endpoint; empty disables telemetry |
+
+Notes:
+
+- startup fails if `HA_TOKEN` is missing
+- `HA_BASE_URL` is not validated on load, but the gateway cannot reach Home
+  Assistant without it
+- if `OTEL_ENDPOINT` is empty, the service installs no-op telemetry providers
+
+## Prerequisites
+
+- Go `1.26`
+- `buf` for protobuf generation
+- a reachable Home Assistant instance
+- a valid Home Assistant long-lived access token
+
+## Generate Protobuf Code
+
+Run from the repo root:
+
+```bash
+buf generate
+```
+
+Generated files are written to `gen/ha/v1`.
+
+## Build
+
+Sync the workspace, then build the gateway:
+
+```bash
+go work sync
+cd ha-gateway
+go build ./...
+```
+
+## Run Locally
+
+Create a local env file:
+
+```bash
+cp ha-gateway/.env.example ha-gateway/.env
+```
+
+Fill in `HA_TOKEN` and `HA_BASE_URL`, then start the server:
+
+```bash
+cd ha-gateway
+go run ./cmd/gateway
+```
+
+The gateway listens on `:50051` by default.
+
+## Smoke Test With grpcurl
+
+Examples against a locally running gateway:
+
+```bash
+# List all light entities
+grpcurl -plaintext -d '{"domain":"light"}' \
+  localhost:50051 ha.v1.EntityService/ListStates
+
+# Get one entity
+grpcurl -plaintext -d '{"entity_id":"light.living_room"}' \
+  localhost:50051 ha.v1.EntityService/GetState
+
+# Turn on a light at 80% brightness
+grpcurl -plaintext -d '{"entity_id":"light.living_room","brightness_pct":80}' \
+  localhost:50051 ha.v1.LightService/TurnOn
+
+# Toggle a light
+grpcurl -plaintext -d '{"entity_id":"light.living_room"}' \
+  localhost:50051 ha.v1.LightService/Toggle
+```
+
+## Docker
+
+Build from the repo root:
+
+```bash
+docker build -f ha-gateway/Dockerfile -t ha-gateway:dev .
+```
+
+Run it with the same env file:
+
+```bash
+docker run --env-file ha-gateway/.env -p 50051:50051 ha-gateway:dev
+```
+
+## Telemetry
+
+When `OTEL_ENDPOINT` is set, the gateway exports:
+
+- traces via OTLP/gRPC
+- metrics via OTLP/gRPC
+
+The service name is `ha-gateway`. When `OTEL_ENDPOINT` is unset, telemetry is
+disabled for local development.
+
+## Current Limitations
+
+- no authentication/authorization on inbound gRPC requests yet
+- `SwitchService` is not implemented
+- `EventService` is not implemented
+- Home Assistant event streaming over WebSocket is not implemented
+- there are currently no unit tests in the repo
+
+The auth note in [ha-gateway/cmd/gateway/main.go](/Users/nik-macbookair/repo/home-service/ha-gateway/cmd/gateway/main.go) explicitly calls out API-key and mTLS as future options before exposing the gateway outside a trusted network.
diff --git a/gen/ha/v1/light.pb.go b/gen/ha/v1/light.pb.go
index 32eea95..d50fd11 100644
--- a/gen/ha/v1/light.pb.go
+++ b/gen/ha/v1/light.pb.go
@@ -240,6 +240,186 @@ func (x *LightResponse) GetState() *EntityState {
 	return nil
 }
 
+type LightEntity struct {
+	state               protoimpl.MessageState `protogen:"open.v1"`
+	EntityId            string                 `protobuf:"bytes,1,opt,name=entity_id,json=entityId,proto3" json:"entity_id,omitempty"`
+	FriendlyName        string                 `protobuf:"bytes,2,opt,name=friendly_name,json=friendlyName,proto3" json:"friendly_name,omitempty"`
+	State               string                 `protobuf:"bytes,3,opt,name=state,proto3" json:"state,omitempty"`
+	SupportedColorModes []string               `protobuf:"bytes,4,rep,name=supported_color_modes,json=supportedColorModes,proto3" json:"supported_color_modes,omitempty"`
+	MinColorTempKelvin  uint32                 `protobuf:"varint,5,opt,name=min_color_temp_kelvin,json=minColorTempKelvin,proto3" json:"min_color_temp_kelvin,omitempty"`
+	MaxColorTempKelvin  uint32                 `protobuf:"varint,6,opt,name=max_color_temp_kelvin,json=maxColorTempKelvin,proto3" json:"max_color_temp_kelvin,omitempty"`
+	IsHueGroup          bool                   `protobuf:"varint,7,opt,name=is_hue_group,json=isHueGroup,proto3" json:"is_hue_group,omitempty"`
+	EffectList          []string               `protobuf:"bytes,8,rep,name=effect_list,json=effectList,proto3" json:"effect_list,omitempty"`
+	unknownFields       protoimpl.UnknownFields
+	sizeCache           protoimpl.SizeCache
+}
+
+func (x *LightEntity) Reset() {
+	*x = LightEntity{}
+	mi := &file_ha_v1_light_proto_msgTypes[4]
+	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+	ms.StoreMessageInfo(mi)
+}
+
+func (x *LightEntity) String() string {
+	return protoimpl.X.MessageStringOf(x)
+}
+
+func (*LightEntity) ProtoMessage() {}
+
+func (x *LightEntity) ProtoReflect() protoreflect.Message {
+	mi := &file_ha_v1_light_proto_msgTypes[4]
+	if x != nil {
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		if ms.LoadMessageInfo() == nil {
+			ms.StoreMessageInfo(mi)
+		}
+		return ms
+	}
+	return mi.MessageOf(x)
+}
+
+// Deprecated: Use LightEntity.ProtoReflect.Descriptor instead.
+func (*LightEntity) Descriptor() ([]byte, []int) {
+	return file_ha_v1_light_proto_rawDescGZIP(), []int{4}
+}
+
+func (x *LightEntity) GetEntityId() string {
+	if x != nil {
+		return x.EntityId
+	}
+	return ""
+}
+
+func (x *LightEntity) GetFriendlyName() string {
+	if x != nil {
+		return x.FriendlyName
+	}
+	return ""
+}
+
+func (x *LightEntity) GetState() string {
+	if x != nil {
+		return x.State
+	}
+	return ""
+}
+
+func (x *LightEntity) GetSupportedColorModes() []string {
+	if x != nil {
+		return x.SupportedColorModes
+	}
+	return nil
+}
+
+func (x *LightEntity) GetMinColorTempKelvin() uint32 {
+	if x != nil {
+		return x.MinColorTempKelvin
+	}
+	return 0
+}
+
+func (x *LightEntity) GetMaxColorTempKelvin() uint32 {
+	if x != nil {
+		return x.MaxColorTempKelvin
+	}
+	return 0
+}
+
+func (x *LightEntity) GetIsHueGroup() bool {
+	if x != nil {
+		return x.IsHueGroup
+	}
+	return false
+}
+
+func (x *LightEntity) GetEffectList() []string {
+	if x != nil {
+		return x.EffectList
+	}
+	return nil
+}
+
+type ListLightsRequest struct {
+	state         protoimpl.MessageState `protogen:"open.v1"`
+	unknownFields protoimpl.UnknownFields
+	sizeCache     protoimpl.SizeCache
+}
+
+func (x *ListLightsRequest) Reset() {
+	*x = ListLightsRequest{}
+	mi := &file_ha_v1_light_proto_msgTypes[5]
+	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+	ms.StoreMessageInfo(mi)
+}
+
+func (x *ListLightsRequest) String() string {
+	return protoimpl.X.MessageStringOf(x)
+}
+
+func (*ListLightsRequest) ProtoMessage() {}
+
+func (x *ListLightsRequest) ProtoReflect() protoreflect.Message {
+	mi := &file_ha_v1_light_proto_msgTypes[5]
+	if x != nil {
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		if ms.LoadMessageInfo() == nil {
+			ms.StoreMessageInfo(mi)
+		}
+		return ms
+	}
+	return mi.MessageOf(x)
+}
+
+// Deprecated: Use ListLightsRequest.ProtoReflect.Descriptor instead.
+func (*ListLightsRequest) Descriptor() ([]byte, []int) {
+	return file_ha_v1_light_proto_rawDescGZIP(), []int{5}
+}
+
+type ListLightsResponse struct {
+	state         protoimpl.MessageState `protogen:"open.v1"`
+	Lights        []*LightEntity         `protobuf:"bytes,1,rep,name=lights,proto3" json:"lights,omitempty"`
+	unknownFields protoimpl.UnknownFields
+	sizeCache     protoimpl.SizeCache
+}
+
+func (x *ListLightsResponse) Reset() {
+	*x = ListLightsResponse{}
+	mi := &file_ha_v1_light_proto_msgTypes[6]
+	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+	ms.StoreMessageInfo(mi)
+}
+
+func (x *ListLightsResponse) String() string {
+	return protoimpl.X.MessageStringOf(x)
+}
+
+func (*ListLightsResponse) ProtoMessage() {}
+
+func (x *ListLightsResponse) ProtoReflect() protoreflect.Message {
+	mi := &file_ha_v1_light_proto_msgTypes[6]
+	if x != nil {
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		if ms.LoadMessageInfo() == nil {
+			ms.StoreMessageInfo(mi)
+		}
+		return ms
+	}
+	return mi.MessageOf(x)
+}
+
+// Deprecated: Use ListLightsResponse.ProtoReflect.Descriptor instead.
+func (*ListLightsResponse) Descriptor() ([]byte, []int) {
+	return file_ha_v1_light_proto_rawDescGZIP(), []int{6}
+}
+
+func (x *ListLightsResponse) GetLights() []*LightEntity {
+	if x != nil {
+		return x.Lights
+	}
+	return nil
+}
+
 var File_ha_v1_light_proto protoreflect.FileDescriptor
 
 const file_ha_v1_light_proto_rawDesc = "" +
@@ -267,11 +447,27 @@ const file_ha_v1_light_proto_rawDesc = "" +
 	"\rToggleRequest\x12\x1b\n" +
 	"\tentity_id\x18\x01 \x01(\tR\bentityId\"9\n" +
 	"\rLightResponse\x12(\n" +
-	"\x05state\x18\x01 \x01(\v2\x12.ha.v1.EntityStateR\x05state2\xb2\x01\n" +
+	"\x05state\x18\x01 \x01(\v2\x12.ha.v1.EntityStateR\x05state\"\xc2\x02\n" +
+	"\vLightEntity\x12\x1b\n" +
+	"\tentity_id\x18\x01 \x01(\tR\bentityId\x12#\n" +
+	"\rfriendly_name\x18\x02 \x01(\tR\ffriendlyName\x12\x14\n" +
+	"\x05state\x18\x03 \x01(\tR\x05state\x122\n" +
+	"\x15supported_color_modes\x18\x04 \x03(\tR\x13supportedColorModes\x121\n" +
+	"\x15min_color_temp_kelvin\x18\x05 \x01(\rR\x12minColorTempKelvin\x121\n" +
+	"\x15max_color_temp_kelvin\x18\x06 \x01(\rR\x12maxColorTempKelvin\x12 \n" +
+	"\fis_hue_group\x18\a \x01(\bR\n" +
+	"isHueGroup\x12\x1f\n" +
+	"\veffect_list\x18\b \x03(\tR\n" +
+	"effectList\"\x13\n" +
+	"\x11ListLightsRequest\"@\n" +
+	"\x12ListLightsResponse\x12*\n" +
+	"\x06lights\x18\x01 \x03(\v2\x12.ha.v1.LightEntityR\x06lights2\xf5\x01\n" +
 	"\fLightService\x124\n" +
 	"\x06TurnOn\x12\x14.ha.v1.TurnOnRequest\x1a\x14.ha.v1.LightResponse\x126\n" +
 	"\aTurnOff\x12\x15.ha.v1.TurnOffRequest\x1a\x14.ha.v1.LightResponse\x124\n" +
-	"\x06Toggle\x12\x14.ha.v1.ToggleRequest\x1a\x14.ha.v1.LightResponseB4Z2gitea.nik4nao.com/nik/home-services/gen/ha/v1;hav1b\x06proto3"
+	"\x06Toggle\x12\x14.ha.v1.ToggleRequest\x1a\x14.ha.v1.LightResponse\x12A\n" +
+	"\n" +
+	"ListLights\x12\x18.ha.v1.ListLightsRequest\x1a\x19.ha.v1.ListLightsResponseB4Z2gitea.nik4nao.com/nik/home-services/gen/ha/v1;hav1b\x06proto3"
 
 var (
 	file_ha_v1_light_proto_rawDescOnce sync.Once
@@ -285,29 +481,35 @@ func file_ha_v1_light_proto_rawDescGZIP() []byte {
 	return file_ha_v1_light_proto_rawDescData
 }
 
-var file_ha_v1_light_proto_msgTypes = make([]protoimpl.MessageInfo, 4)
+var file_ha_v1_light_proto_msgTypes = make([]protoimpl.MessageInfo, 7)
 var file_ha_v1_light_proto_goTypes = []any{
-	(*TurnOnRequest)(nil),  // 0: ha.v1.TurnOnRequest
-	(*TurnOffRequest)(nil), // 1: ha.v1.TurnOffRequest
-	(*ToggleRequest)(nil),  // 2: ha.v1.ToggleRequest
-	(*LightResponse)(nil),  // 3: ha.v1.LightResponse
-	(*RGBColor)(nil),       // 4: ha.v1.RGBColor
-	(*EntityState)(nil),    // 5: ha.v1.EntityState
+	(*TurnOnRequest)(nil),      // 0: ha.v1.TurnOnRequest
+	(*TurnOffRequest)(nil),     // 1: ha.v1.TurnOffRequest
+	(*ToggleRequest)(nil),      // 2: ha.v1.ToggleRequest
+	(*LightResponse)(nil),      // 3: ha.v1.LightResponse
+	(*LightEntity)(nil),        // 4: ha.v1.LightEntity
+	(*ListLightsRequest)(nil),  // 5: ha.v1.ListLightsRequest
+	(*ListLightsResponse)(nil), // 6: ha.v1.ListLightsResponse
+	(*RGBColor)(nil),           // 7: ha.v1.RGBColor
+	(*EntityState)(nil),        // 8: ha.v1.EntityState
 }
 var file_ha_v1_light_proto_depIdxs = []int32{
-	4, // 0: ha.v1.TurnOnRequest.rgb_color:type_name -> ha.v1.RGBColor
-	5, // 1: ha.v1.LightResponse.state:type_name -> ha.v1.EntityState
-	0, // 2: ha.v1.LightService.TurnOn:input_type -> ha.v1.TurnOnRequest
-	1, // 3: ha.v1.LightService.TurnOff:input_type -> ha.v1.TurnOffRequest
-	2, // 4: ha.v1.LightService.Toggle:input_type -> ha.v1.ToggleRequest
-	3, // 5: ha.v1.LightService.TurnOn:output_type -> ha.v1.LightResponse
-	3, // 6: ha.v1.LightService.TurnOff:output_type -> ha.v1.LightResponse
-	3, // 7: ha.v1.LightService.Toggle:output_type -> ha.v1.LightResponse
-	5, // [5:8] is the sub-list for method output_type
-	2, // [2:5] is the sub-list for method input_type
-	2, // [2:2] is the sub-list for extension type_name
-	2, // [2:2] is the sub-list for extension extendee
-	0, // [0:2] is the sub-list for field type_name
+	7, // 0: ha.v1.TurnOnRequest.rgb_color:type_name -> ha.v1.RGBColor
+	8, // 1: ha.v1.LightResponse.state:type_name -> ha.v1.EntityState
+	4, // 2: ha.v1.ListLightsResponse.lights:type_name -> ha.v1.LightEntity
+	0, // 3: ha.v1.LightService.TurnOn:input_type -> ha.v1.TurnOnRequest
+	1, // 4: ha.v1.LightService.TurnOff:input_type -> ha.v1.TurnOffRequest
+	2, // 5: ha.v1.LightService.Toggle:input_type -> ha.v1.ToggleRequest
+	5, // 6: ha.v1.LightService.ListLights:input_type -> ha.v1.ListLightsRequest
+	3, // 7: ha.v1.LightService.TurnOn:output_type -> ha.v1.LightResponse
+	3, // 8: ha.v1.LightService.TurnOff:output_type -> ha.v1.LightResponse
+	3, // 9: ha.v1.LightService.Toggle:output_type -> ha.v1.LightResponse
+	6, // 10: ha.v1.LightService.ListLights:output_type -> ha.v1.ListLightsResponse
+	7, // [7:11] is the sub-list for method output_type
+	3, // [3:7] is the sub-list for method input_type
+	3, // [3:3] is the sub-list for extension type_name
+	3, // [3:3] is the sub-list for extension extendee
+	0, // [0:3] is the sub-list for field type_name
 }
 
 func init() { file_ha_v1_light_proto_init() }
@@ -324,7 +526,7 @@ func file_ha_v1_light_proto_init() {
 			GoPackagePath: reflect.TypeOf(x{}).PkgPath(),
 			RawDescriptor: unsafe.Slice(unsafe.StringData(file_ha_v1_light_proto_rawDesc), len(file_ha_v1_light_proto_rawDesc)),
 			NumEnums:      0,
-			NumMessages:   4,
+			NumMessages:   7,
 			NumExtensions: 0,
 			NumServices:   1,
 		},
diff --git a/gen/ha/v1/light_grpc.pb.go b/gen/ha/v1/light_grpc.pb.go
index 7ae446d..01c5c4c 100644
--- a/gen/ha/v1/light_grpc.pb.go
+++ b/gen/ha/v1/light_grpc.pb.go
@@ -19,9 +19,10 @@ import (
 const _ = grpc.SupportPackageIsVersion9
 
 const (
-	LightService_TurnOn_FullMethodName  = "/ha.v1.LightService/TurnOn"
-	LightService_TurnOff_FullMethodName = "/ha.v1.LightService/TurnOff"
-	LightService_Toggle_FullMethodName  = "/ha.v1.LightService/Toggle"
+	LightService_TurnOn_FullMethodName     = "/ha.v1.LightService/TurnOn"
+	LightService_TurnOff_FullMethodName    = "/ha.v1.LightService/TurnOff"
+	LightService_Toggle_FullMethodName     = "/ha.v1.LightService/Toggle"
+	LightService_ListLights_FullMethodName = "/ha.v1.LightService/ListLights"
 )
 
 // LightServiceClient is the client API for LightService service.
@@ -31,6 +32,7 @@ type LightServiceClient interface {
 	TurnOn(ctx context.Context, in *TurnOnRequest, opts ...grpc.CallOption) (*LightResponse, error)
 	TurnOff(ctx context.Context, in *TurnOffRequest, opts ...grpc.CallOption) (*LightResponse, error)
 	Toggle(ctx context.Context, in *ToggleRequest, opts ...grpc.CallOption) (*LightResponse, error)
+	ListLights(ctx context.Context, in *ListLightsRequest, opts ...grpc.CallOption) (*ListLightsResponse, error)
 }
 
 type lightServiceClient struct {
@@ -71,6 +73,16 @@ func (c *lightServiceClient) Toggle(ctx context.Context, in *ToggleRequest, opts
 	return out, nil
 }
 
+func (c *lightServiceClient) ListLights(ctx context.Context, in *ListLightsRequest, opts ...grpc.CallOption) (*ListLightsResponse, error) {
+	cOpts := append([]grpc.CallOption{grpc.StaticMethod()}, opts...)
+	out := new(ListLightsResponse)
+	err := c.cc.Invoke(ctx, LightService_ListLights_FullMethodName, in, out, cOpts...)
+	if err != nil {
+		return nil, err
+	}
+	return out, nil
+}
+
 // LightServiceServer is the server API for LightService service.
 // All implementations must embed UnimplementedLightServiceServer
 // for forward compatibility.
@@ -78,6 +90,7 @@ type LightServiceServer interface {
 	TurnOn(context.Context, *TurnOnRequest) (*LightResponse, error)
 	TurnOff(context.Context, *TurnOffRequest) (*LightResponse, error)
 	Toggle(context.Context, *ToggleRequest) (*LightResponse, error)
+	ListLights(context.Context, *ListLightsRequest) (*ListLightsResponse, error)
 	mustEmbedUnimplementedLightServiceServer()
 }
 
@@ -97,6 +110,9 @@ func (UnimplementedLightServiceServer) TurnOff(context.Context, *TurnOffRequest)
 func (UnimplementedLightServiceServer) Toggle(context.Context, *ToggleRequest) (*LightResponse, error) {
 	return nil, status.Error(codes.Unimplemented, "method Toggle not implemented")
 }
+func (UnimplementedLightServiceServer) ListLights(context.Context, *ListLightsRequest) (*ListLightsResponse, error) {
+	return nil, status.Error(codes.Unimplemented, "method ListLights not implemented")
+}
 func (UnimplementedLightServiceServer) mustEmbedUnimplementedLightServiceServer() {}
 func (UnimplementedLightServiceServer) testEmbeddedByValue()                      {}
 
@@ -172,6 +188,24 @@ func _LightService_Toggle_Handler(srv interface{}, ctx context.Context, dec func
 	return interceptor(ctx, in, info, handler)
 }
 
+func _LightService_ListLights_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
+	in := new(ListLightsRequest)
+	if err := dec(in); err != nil {
+		return nil, err
+	}
+	if interceptor == nil {
+		return srv.(LightServiceServer).ListLights(ctx, in)
+	}
+	info := &grpc.UnaryServerInfo{
+		Server:     srv,
+		FullMethod: LightService_ListLights_FullMethodName,
+	}
+	handler := func(ctx context.Context, req interface{}) (interface{}, error) {
+		return srv.(LightServiceServer).ListLights(ctx, req.(*ListLightsRequest))
+	}
+	return interceptor(ctx, in, info, handler)
+}
+
 // LightService_ServiceDesc is the grpc.ServiceDesc for LightService service.
 // It's only intended for direct use with grpc.RegisterService,
 // and not to be introspected or modified (even as a copy)
@@ -191,6 +225,10 @@ var LightService_ServiceDesc = grpc.ServiceDesc{
 			MethodName: "Toggle",
 			Handler:    _LightService_Toggle_Handler,
 		},
+		{
+			MethodName: "ListLights",
+			Handler:    _LightService_ListLights_Handler,
+		},
 	},
 	Streams:  []grpc.StreamDesc{},
 	Metadata: "ha/v1/light.proto",
diff --git a/gen/ha/v1/switch.pb.go b/gen/ha/v1/switch.pb.go
index ec9c635..285ddc1 100644
--- a/gen/ha/v1/switch.pb.go
+++ b/gen/ha/v1/switch.pb.go
@@ -109,6 +109,154 @@ func (x *SwitchResponse) GetState() *EntityState {
 	return nil
 }
 
+type SwitchEntity struct {
+	state         protoimpl.MessageState `protogen:"open.v1"`
+	EntityId      string                 `protobuf:"bytes,1,opt,name=entity_id,json=entityId,proto3" json:"entity_id,omitempty"`
+	FriendlyName  string                 `protobuf:"bytes,2,opt,name=friendly_name,json=friendlyName,proto3" json:"friendly_name,omitempty"`
+	State         string                 `protobuf:"bytes,3,opt,name=state,proto3" json:"state,omitempty"`
+	DeviceClass   string                 `protobuf:"bytes,4,opt,name=device_class,json=deviceClass,proto3" json:"device_class,omitempty"`
+	unknownFields protoimpl.UnknownFields
+	sizeCache     protoimpl.SizeCache
+}
+
+func (x *SwitchEntity) Reset() {
+	*x = SwitchEntity{}
+	mi := &file_ha_v1_switch_proto_msgTypes[2]
+	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+	ms.StoreMessageInfo(mi)
+}
+
+func (x *SwitchEntity) String() string {
+	return protoimpl.X.MessageStringOf(x)
+}
+
+func (*SwitchEntity) ProtoMessage() {}
+
+func (x *SwitchEntity) ProtoReflect() protoreflect.Message {
+	mi := &file_ha_v1_switch_proto_msgTypes[2]
+	if x != nil {
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		if ms.LoadMessageInfo() == nil {
+			ms.StoreMessageInfo(mi)
+		}
+		return ms
+	}
+	return mi.MessageOf(x)
+}
+
+// Deprecated: Use SwitchEntity.ProtoReflect.Descriptor instead.
+func (*SwitchEntity) Descriptor() ([]byte, []int) {
+	return file_ha_v1_switch_proto_rawDescGZIP(), []int{2}
+}
+
+func (x *SwitchEntity) GetEntityId() string {
+	if x != nil {
+		return x.EntityId
+	}
+	return ""
+}
+
+func (x *SwitchEntity) GetFriendlyName() string {
+	if x != nil {
+		return x.FriendlyName
+	}
+	return ""
+}
+
+func (x *SwitchEntity) GetState() string {
+	if x != nil {
+		return x.State
+	}
+	return ""
+}
+
+func (x *SwitchEntity) GetDeviceClass() string {
+	if x != nil {
+		return x.DeviceClass
+	}
+	return ""
+}
+
+type ListSwitchesRequest struct {
+	state         protoimpl.MessageState `protogen:"open.v1"`
+	unknownFields protoimpl.UnknownFields
+	sizeCache     protoimpl.SizeCache
+}
+
+func (x *ListSwitchesRequest) Reset() {
+	*x = ListSwitchesRequest{}
+	mi := &file_ha_v1_switch_proto_msgTypes[3]
+	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+	ms.StoreMessageInfo(mi)
+}
+
+func (x *ListSwitchesRequest) String() string {
+	return protoimpl.X.MessageStringOf(x)
+}
+
+func (*ListSwitchesRequest) ProtoMessage() {}
+
+func (x *ListSwitchesRequest) ProtoReflect() protoreflect.Message {
+	mi := &file_ha_v1_switch_proto_msgTypes[3]
+	if x != nil {
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		if ms.LoadMessageInfo() == nil {
+			ms.StoreMessageInfo(mi)
+		}
+		return ms
+	}
+	return mi.MessageOf(x)
+}
+
+// Deprecated: Use ListSwitchesRequest.ProtoReflect.Descriptor instead.
+func (*ListSwitchesRequest) Descriptor() ([]byte, []int) {
+	return file_ha_v1_switch_proto_rawDescGZIP(), []int{3}
+}
+
+type ListSwitchesResponse struct {
+	state         protoimpl.MessageState `protogen:"open.v1"`
+	Switches      []*SwitchEntity        `protobuf:"bytes,1,rep,name=switches,proto3" json:"switches,omitempty"`
+	unknownFields protoimpl.UnknownFields
+	sizeCache     protoimpl.SizeCache
+}
+
+func (x *ListSwitchesResponse) Reset() {
+	*x = ListSwitchesResponse{}
+	mi := &file_ha_v1_switch_proto_msgTypes[4]
+	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+	ms.StoreMessageInfo(mi)
+}
+
+func (x *ListSwitchesResponse) String() string {
+	return protoimpl.X.MessageStringOf(x)
+}
+
+func (*ListSwitchesResponse) ProtoMessage() {}
+
+func (x *ListSwitchesResponse) ProtoReflect() protoreflect.Message {
+	mi := &file_ha_v1_switch_proto_msgTypes[4]
+	if x != nil {
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		if ms.LoadMessageInfo() == nil {
+			ms.StoreMessageInfo(mi)
+		}
+		return ms
+	}
+	return mi.MessageOf(x)
+}
+
+// Deprecated: Use ListSwitchesResponse.ProtoReflect.Descriptor instead.
+func (*ListSwitchesResponse) Descriptor() ([]byte, []int) {
+	return file_ha_v1_switch_proto_rawDescGZIP(), []int{4}
+}
+
+func (x *ListSwitchesResponse) GetSwitches() []*SwitchEntity {
+	if x != nil {
+		return x.Switches
+	}
+	return nil
+}
+
 var File_ha_v1_switch_proto protoreflect.FileDescriptor
 
 const file_ha_v1_switch_proto_rawDesc = "" +
@@ -117,11 +265,20 @@ const file_ha_v1_switch_proto_rawDesc = "" +
 	"\rSwitchRequest\x12\x1b\n" +
 	"\tentity_id\x18\x01 \x01(\tR\bentityId\":\n" +
 	"\x0eSwitchResponse\x12(\n" +
-	"\x05state\x18\x01 \x01(\v2\x12.ha.v1.EntityStateR\x05state2\xb5\x01\n" +
+	"\x05state\x18\x01 \x01(\v2\x12.ha.v1.EntityStateR\x05state\"\x89\x01\n" +
+	"\fSwitchEntity\x12\x1b\n" +
+	"\tentity_id\x18\x01 \x01(\tR\bentityId\x12#\n" +
+	"\rfriendly_name\x18\x02 \x01(\tR\ffriendlyName\x12\x14\n" +
+	"\x05state\x18\x03 \x01(\tR\x05state\x12!\n" +
+	"\fdevice_class\x18\x04 \x01(\tR\vdeviceClass\"\x15\n" +
+	"\x13ListSwitchesRequest\"G\n" +
+	"\x14ListSwitchesResponse\x12/\n" +
+	"\bswitches\x18\x01 \x03(\v2\x13.ha.v1.SwitchEntityR\bswitches2\xfe\x01\n" +
 	"\rSwitchService\x125\n" +
 	"\x06TurnOn\x12\x14.ha.v1.SwitchRequest\x1a\x15.ha.v1.SwitchResponse\x126\n" +
 	"\aTurnOff\x12\x14.ha.v1.SwitchRequest\x1a\x15.ha.v1.SwitchResponse\x125\n" +
-	"\x06Toggle\x12\x14.ha.v1.SwitchRequest\x1a\x15.ha.v1.SwitchResponseB4Z2gitea.nik4nao.com/nik/home-services/gen/ha/v1;hav1b\x06proto3"
+	"\x06Toggle\x12\x14.ha.v1.SwitchRequest\x1a\x15.ha.v1.SwitchResponse\x12G\n" +
+	"\fListSwitches\x12\x1a.ha.v1.ListSwitchesRequest\x1a\x1b.ha.v1.ListSwitchesResponseB4Z2gitea.nik4nao.com/nik/home-services/gen/ha/v1;hav1b\x06proto3"
 
 var (
 	file_ha_v1_switch_proto_rawDescOnce sync.Once
@@ -135,25 +292,31 @@ func file_ha_v1_switch_proto_rawDescGZIP() []byte {
 	return file_ha_v1_switch_proto_rawDescData
 }
 
-var file_ha_v1_switch_proto_msgTypes = make([]protoimpl.MessageInfo, 2)
+var file_ha_v1_switch_proto_msgTypes = make([]protoimpl.MessageInfo, 5)
 var file_ha_v1_switch_proto_goTypes = []any{
-	(*SwitchRequest)(nil),  // 0: ha.v1.SwitchRequest
-	(*SwitchResponse)(nil), // 1: ha.v1.SwitchResponse
-	(*EntityState)(nil),    // 2: ha.v1.EntityState
+	(*SwitchRequest)(nil),        // 0: ha.v1.SwitchRequest
+	(*SwitchResponse)(nil),       // 1: ha.v1.SwitchResponse
+	(*SwitchEntity)(nil),         // 2: ha.v1.SwitchEntity
+	(*ListSwitchesRequest)(nil),  // 3: ha.v1.ListSwitchesRequest
+	(*ListSwitchesResponse)(nil), // 4: ha.v1.ListSwitchesResponse
+	(*EntityState)(nil),          // 5: ha.v1.EntityState
 }
 var file_ha_v1_switch_proto_depIdxs = []int32{
-	2, // 0: ha.v1.SwitchResponse.state:type_name -> ha.v1.EntityState
-	0, // 1: ha.v1.SwitchService.TurnOn:input_type -> ha.v1.SwitchRequest
-	0, // 2: ha.v1.SwitchService.TurnOff:input_type -> ha.v1.SwitchRequest
-	0, // 3: ha.v1.SwitchService.Toggle:input_type -> ha.v1.SwitchRequest
-	1, // 4: ha.v1.SwitchService.TurnOn:output_type -> ha.v1.SwitchResponse
-	1, // 5: ha.v1.SwitchService.TurnOff:output_type -> ha.v1.SwitchResponse
-	1, // 6: ha.v1.SwitchService.Toggle:output_type -> ha.v1.SwitchResponse
-	4, // [4:7] is the sub-list for method output_type
-	1, // [1:4] is the sub-list for method input_type
-	1, // [1:1] is the sub-list for extension type_name
-	1, // [1:1] is the sub-list for extension extendee
-	0, // [0:1] is the sub-list for field type_name
+	5, // 0: ha.v1.SwitchResponse.state:type_name -> ha.v1.EntityState
+	2, // 1: ha.v1.ListSwitchesResponse.switches:type_name -> ha.v1.SwitchEntity
+	0, // 2: ha.v1.SwitchService.TurnOn:input_type -> ha.v1.SwitchRequest
+	0, // 3: ha.v1.SwitchService.TurnOff:input_type -> ha.v1.SwitchRequest
+	0, // 4: ha.v1.SwitchService.Toggle:input_type -> ha.v1.SwitchRequest
+	3, // 5: ha.v1.SwitchService.ListSwitches:input_type -> ha.v1.ListSwitchesRequest
+	1, // 6: ha.v1.SwitchService.TurnOn:output_type -> ha.v1.SwitchResponse
+	1, // 7: ha.v1.SwitchService.TurnOff:output_type -> ha.v1.SwitchResponse
+	1, // 8: ha.v1.SwitchService.Toggle:output_type -> ha.v1.SwitchResponse
+	4, // 9: ha.v1.SwitchService.ListSwitches:output_type -> ha.v1.ListSwitchesResponse
+	6, // [6:10] is the sub-list for method output_type
+	2, // [2:6] is the sub-list for method input_type
+	2, // [2:2] is the sub-list for extension type_name
+	2, // [2:2] is the sub-list for extension extendee
+	0, // [0:2] is the sub-list for field type_name
 }
 
 func init() { file_ha_v1_switch_proto_init() }
@@ -168,7 +331,7 @@ func file_ha_v1_switch_proto_init() {
 			GoPackagePath: reflect.TypeOf(x{}).PkgPath(),
 			RawDescriptor: unsafe.Slice(unsafe.StringData(file_ha_v1_switch_proto_rawDesc), len(file_ha_v1_switch_proto_rawDesc)),
 			NumEnums:      0,
-			NumMessages:   2,
+			NumMessages:   5,
 			NumExtensions: 0,
 			NumServices:   1,
 		},
diff --git a/gen/ha/v1/switch_grpc.pb.go b/gen/ha/v1/switch_grpc.pb.go
index 806bc0e..a89c523 100644
--- a/gen/ha/v1/switch_grpc.pb.go
+++ b/gen/ha/v1/switch_grpc.pb.go
@@ -19,24 +19,20 @@ import (
 const _ = grpc.SupportPackageIsVersion9
 
 const (
-	SwitchService_TurnOn_FullMethodName  = "/ha.v1.SwitchService/TurnOn"
-	SwitchService_TurnOff_FullMethodName = "/ha.v1.SwitchService/TurnOff"
-	SwitchService_Toggle_FullMethodName  = "/ha.v1.SwitchService/Toggle"
+	SwitchService_TurnOn_FullMethodName       = "/ha.v1.SwitchService/TurnOn"
+	SwitchService_TurnOff_FullMethodName      = "/ha.v1.SwitchService/TurnOff"
+	SwitchService_Toggle_FullMethodName       = "/ha.v1.SwitchService/Toggle"
+	SwitchService_ListSwitches_FullMethodName = "/ha.v1.SwitchService/ListSwitches"
 )
 
 // SwitchServiceClient is the client API for SwitchService service.
 //
 // For semantics around ctx use and closing/ending streaming RPCs, please refer to https://pkg.go.dev/google.golang.org/grpc/?tab=doc#ClientConn.NewStream.
-//
-// TODO: implement SwitchService. Follow the same pattern as LightService:
-// - domain type in core/domain/switch.go
-// - port interface in core/ports/driving/switch.go
-// - application logic in app/switch.go
-// - gRPC adapter in adapters/primary/grpc/switch.go
 type SwitchServiceClient interface {
 	TurnOn(ctx context.Context, in *SwitchRequest, opts ...grpc.CallOption) (*SwitchResponse, error)
 	TurnOff(ctx context.Context, in *SwitchRequest, opts ...grpc.CallOption) (*SwitchResponse, error)
 	Toggle(ctx context.Context, in *SwitchRequest, opts ...grpc.CallOption) (*SwitchResponse, error)
+	ListSwitches(ctx context.Context, in *ListSwitchesRequest, opts ...grpc.CallOption) (*ListSwitchesResponse, error)
 }
 
 type switchServiceClient struct {
@@ -77,19 +73,24 @@ func (c *switchServiceClient) Toggle(ctx context.Context, in *SwitchRequest, opt
 	return out, nil
 }
 
+func (c *switchServiceClient) ListSwitches(ctx context.Context, in *ListSwitchesRequest, opts ...grpc.CallOption) (*ListSwitchesResponse, error) {
+	cOpts := append([]grpc.CallOption{grpc.StaticMethod()}, opts...)
+	out := new(ListSwitchesResponse)
+	err := c.cc.Invoke(ctx, SwitchService_ListSwitches_FullMethodName, in, out, cOpts...)
+	if err != nil {
+		return nil, err
+	}
+	return out, nil
+}
+
 // SwitchServiceServer is the server API for SwitchService service.
 // All implementations must embed UnimplementedSwitchServiceServer
 // for forward compatibility.
-//
-// TODO: implement SwitchService. Follow the same pattern as LightService:
-// - domain type in core/domain/switch.go
-// - port interface in core/ports/driving/switch.go
-// - application logic in app/switch.go
-// - gRPC adapter in adapters/primary/grpc/switch.go
 type SwitchServiceServer interface {
 	TurnOn(context.Context, *SwitchRequest) (*SwitchResponse, error)
 	TurnOff(context.Context, *SwitchRequest) (*SwitchResponse, error)
 	Toggle(context.Context, *SwitchRequest) (*SwitchResponse, error)
+	ListSwitches(context.Context, *ListSwitchesRequest) (*ListSwitchesResponse, error)
 	mustEmbedUnimplementedSwitchServiceServer()
 }
 
@@ -109,6 +110,9 @@ func (UnimplementedSwitchServiceServer) TurnOff(context.Context, *SwitchRequest)
 func (UnimplementedSwitchServiceServer) Toggle(context.Context, *SwitchRequest) (*SwitchResponse, error) {
 	return nil, status.Error(codes.Unimplemented, "method Toggle not implemented")
 }
+func (UnimplementedSwitchServiceServer) ListSwitches(context.Context, *ListSwitchesRequest) (*ListSwitchesResponse, error) {
+	return nil, status.Error(codes.Unimplemented, "method ListSwitches not implemented")
+}
 func (UnimplementedSwitchServiceServer) mustEmbedUnimplementedSwitchServiceServer() {}
 func (UnimplementedSwitchServiceServer) testEmbeddedByValue()                       {}
 
@@ -184,6 +188,24 @@ func _SwitchService_Toggle_Handler(srv interface{}, ctx context.Context, dec fun
 	return interceptor(ctx, in, info, handler)
 }
 
+func _SwitchService_ListSwitches_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
+	in := new(ListSwitchesRequest)
+	if err := dec(in); err != nil {
+		return nil, err
+	}
+	if interceptor == nil {
+		return srv.(SwitchServiceServer).ListSwitches(ctx, in)
+	}
+	info := &grpc.UnaryServerInfo{
+		Server:     srv,
+		FullMethod: SwitchService_ListSwitches_FullMethodName,
+	}
+	handler := func(ctx context.Context, req interface{}) (interface{}, error) {
+		return srv.(SwitchServiceServer).ListSwitches(ctx, req.(*ListSwitchesRequest))
+	}
+	return interceptor(ctx, in, info, handler)
+}
+
 // SwitchService_ServiceDesc is the grpc.ServiceDesc for SwitchService service.
 // It's only intended for direct use with grpc.RegisterService,
 // and not to be introspected or modified (even as a copy)
@@ -203,6 +225,10 @@ var SwitchService_ServiceDesc = grpc.ServiceDesc{
 			MethodName: "Toggle",
 			Handler:    _SwitchService_Toggle_Handler,
 		},
+		{
+			MethodName: "ListSwitches",
+			Handler:    _SwitchService_ListSwitches_Handler,
+		},
 	},
 	Streams:  []grpc.StreamDesc{},
 	Metadata: "ha/v1/switch.proto",
diff --git a/go.work.sum b/go.work.sum
index 439f9d5..6eed3c9 100644
--- a/go.work.sum
+++ b/go.work.sum
@@ -4,12 +4,10 @@ cloud.google.com/go/compute/metadata v0.6.0/go.mod h1:FjyFAW1MW0C203CEOMDTu3Dk1F
 cloud.google.com/go/compute/metadata v0.9.0/go.mod h1:E0bWwX5wTnLPedCKqk3pJmVgCBSM6qQI1yTBdEb3C10=
 github.com/GoogleCloudPlatform/opentelemetry-operations-go/detectors/gcp v1.25.0/go.mod h1:obipzmGjfSjam60XLwGfqUkJsfiheAl+TUjG+4yzyPM=
 github.com/GoogleCloudPlatform/opentelemetry-operations-go/detectors/gcp v1.30.0/go.mod h1:P4WPRUkOhJC13W//jWpyfJNDAIpvRbAUIYLX/4jtlE0=
-github.com/cenkalti/backoff/v4 v4.3.0 h1:MyRJ/UdXutAwSAT+s3wNd7MfTIcy71VQueUuFK343L8=
-github.com/cenkalti/backoff/v4 v4.3.0/go.mod h1:Y3VNntkOUPxTVeUxJ/G5vcM//AlwfmyYozVcomhLiZE=
+github.com/antihax/optional v1.0.0/go.mod h1:uupD/76wgC+ih3iEmQUL+0Ugr19nfwCT1kdvxnR2qWY=
 github.com/cncf/xds/go v0.0.0-20241223141626-cff3c89139a3/go.mod h1:W+zGtBO5Y1IgJhy4+A9GOqVhqLpfZi+vwmdNXUehLA8=
 github.com/cncf/xds/go v0.0.0-20251210132809-ee656c7534f5/go.mod h1:KdCmV+x/BuvyMxRnYBlmVaq4OLiKW6iRQfvC62cvdkI=
 github.com/creack/pty v1.1.9/go.mod h1:oKZEueFk5CKHvIhNR5MUki03XCEU+Q6VDXinZuGJ33E=
-github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/envoyproxy/go-control-plane v0.13.4/go.mod h1:kDfuBlDVsSj2MjrLEtRWtHlsWIFcGyB2RMO44Dc5GZA=
 github.com/envoyproxy/go-control-plane v0.14.0/go.mod h1:NcS5X47pLl/hfqxU70yPwL9ZMkUlwlKxtAohpi2wBEU=
@@ -19,38 +17,26 @@ github.com/envoyproxy/go-control-plane/ratelimit v0.1.0/go.mod h1:Wk+tMFAFbCXaJP
 github.com/envoyproxy/protoc-gen-validate v1.2.1/go.mod h1:d/C80l/jxXLdfEIhX1W2TmLfsJ31lvEjwamM4DxlWXU=
 github.com/envoyproxy/protoc-gen-validate v1.3.0/go.mod h1:HvYl7zwPa5mffgyeTUHA9zHIH36nmrm7oCbo4YKoSWA=
 github.com/go-jose/go-jose/v4 v4.1.3/go.mod h1:x4oUasVrzR7071A4TnHLGSPpNOm2a21K9Kf04k1rs08=
-github.com/go-logr/logr v1.2.2/go.mod h1:jdQByPbusPIv2/zmleS9BjJVeZ6kBagPoEUsqbVz/1A=
 github.com/go-logr/logr v1.4.2 h1:6pFjapn8bFcIbiKo3XT4j/BhANplGihG6tvd+8rYgrY=
 github.com/go-logr/logr v1.4.2/go.mod h1:9T104GzyrTigFIr8wt5mBrctHMim0Nb2HLGrmQ40KvY=
 github.com/golang/glog v1.2.4/go.mod h1:6AhwSGph0fcJtXVM/PEHPqZlFeoLxhs7/t5UDAwmO+w=
 github.com/golang/glog v1.2.5/go.mod h1:6AhwSGph0fcJtXVM/PEHPqZlFeoLxhs7/t5UDAwmO+w=
 github.com/golang/protobuf v1.5.0/go.mod h1:FsONVRAS9T7sI+LIUmWTfcYkHO4aIWwzhcaSAoJOfIk=
 github.com/google/go-cmp v0.5.5/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
-github.com/grpc-ecosystem/grpc-gateway/v2 v2.26.1 h1:e9Rjr40Z98/clHv5Yg79Is0NtosR5LXRvdr7o/6NwbA=
-github.com/grpc-ecosystem/grpc-gateway/v2 v2.26.1/go.mod h1:tIxuGz/9mpox++sgp9fJjHO0+q1X9/UOWd798aAm22M=
-github.com/joho/godotenv v1.5.1 h1:7eLL/+HRGLY0ldzfGMeQkb7vMd0as4CfYvUVzLqw0N0=
-github.com/joho/godotenv v1.5.1/go.mod h1:f4LDr5Voq0i2e/R5DDNOoa2zzDfwtkZa6DnEwAbqwq4=
+github.com/kr/pretty v0.3.1/go.mod h1:hoEshYVHaxMs3cyo3Yncou5ZscifuDolrwPKZanG3xk=
 github.com/kr/text v0.2.0/go.mod h1:eLer722TekiGuMkidMxC/pM04lWEeraHUUmBw8l2grE=
 github.com/planetscale/vtprotobuf v0.6.1-0.20240319094008-0393e58bdf10/go.mod h1:t/avpk3KcrXxUnYOhZhMXJlSEyie6gQbtLq5NM3loB8=
-github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/pmezard/go-difflib v1.0.1-0.20181226105442-5d4384ee4fb2/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/rogpeppe/fastuuid v1.2.0/go.mod h1:jVj6XXZzXRy/MSR5jhDC/2q6DgLz+nrA6LYCDYWNEvQ=
+github.com/rogpeppe/go-internal v1.14.1/go.mod h1:MaRKkUm5W0goXpeCfT7UZI6fk/L7L7so1lCWt35ZSgc=
 github.com/spiffe/go-spiffe/v2 v2.6.0/go.mod h1:gm2SeUoMZEtpnzPNs2Csc0D/gX33k1xIx7lEzqblHEs=
 github.com/stretchr/testify v1.10.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=
-github.com/stretchr/testify v1.11.1/go.mod h1:wZwfW3scLgRK+23gO65QZefKpKQRnfz6sD981Nm4B6U=
 go.opentelemetry.io/auto/sdk v1.1.0 h1:cH53jehLUN6UFLY71z+NDOiNJqDdPRaXzTel0sJySYA=
 go.opentelemetry.io/auto/sdk v1.1.0/go.mod h1:3wSPjt5PWp2RhlCcmmOial7AvC4DQqZb7a7wCow3W8A=
 go.opentelemetry.io/contrib/detectors/gcp v1.34.0/go.mod h1:cV4BMFcscUR/ckqLkbfQmF0PRsq8w/lMGzdbCSveBHo=
 go.opentelemetry.io/contrib/detectors/gcp v1.39.0/go.mod h1:t/OGqzHBa5v6RHZwrDBJ2OirWc+4q/w2fTbLZwAKjTk=
-go.opentelemetry.io/contrib/instrumentation/google.golang.org/grpc/otelgrpc v0.60.0 h1:x7wzEgXfnzJcHDwStJT+mxOz4etr2EcexjqhBvmoakw=
-go.opentelemetry.io/contrib/instrumentation/google.golang.org/grpc/otelgrpc v0.60.0/go.mod h1:rg+RlpR5dKwaS95IyyZqj5Wd4E13lk/msnTS0Xl9lJM=
 go.opentelemetry.io/otel v1.35.0 h1:xKWKPxrxB6OtMCbmMY021CqC45J+3Onta9MqjhnusiQ=
 go.opentelemetry.io/otel v1.35.0/go.mod h1:UEqy8Zp11hpkUrL73gSlELM0DupHoiq72dR+Zqel/+Y=
-go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetricgrpc v1.35.0 h1:QcFwRrZLc82r8wODjvyCbP7Ifp3UANaBSmhDSFjnqSc=
-go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetricgrpc v1.35.0/go.mod h1:CXIWhUomyWBG/oY2/r/kLp6K/cmx9e/7DLpBuuGdLCA=
-go.opentelemetry.io/otel/exporters/otlp/otlptrace v1.35.0 h1:1fTNlAIJZGWLP5FVu0fikVry1IsiUnXjf7QFvoNN3Xw=
-go.opentelemetry.io/otel/exporters/otlp/otlptrace v1.35.0/go.mod h1:zjPK58DtkqQFn+YUMbx0M2XV3QgKU0gS9LeGohREyK4=
-go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracegrpc v1.35.0 h1:m639+BofXTvcY1q8CGs4ItwQarYtJPOWmVobfM1HpVI=
-go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracegrpc v1.35.0/go.mod h1:LjReUci/F4BUyv+y4dwnq3h/26iNOeC3wAIqgvTIZVo=
 go.opentelemetry.io/otel/metric v1.35.0 h1:0znxYu2SNyuMSQT4Y9WDWej0VpcsxkuklLa4/siN90M=
 go.opentelemetry.io/otel/metric v1.35.0/go.mod h1:nKVFgxBZ2fReX6IlyW28MgZojkoAkJGaE8CpgeAU3oE=
 go.opentelemetry.io/otel/sdk v1.35.0 h1:iPctf8iprVySXSKJffSS79eOjl9pvxV9ZqOWT0QejKY=
@@ -59,11 +45,10 @@ go.opentelemetry.io/otel/sdk/metric v1.35.0 h1:1RriWBmCKgkeHEhM7a2uMjMUfP7MsOF5J
 go.opentelemetry.io/otel/sdk/metric v1.35.0/go.mod h1:is6XYCUMpcKi+ZsOvfluY5YstFnhW0BidkR+gL+qN+w=
 go.opentelemetry.io/otel/trace v1.35.0 h1:dPpEfJu1sDIqruz7BHFG3c7528f6ddfSWfFDVt/xgMs=
 go.opentelemetry.io/otel/trace v1.35.0/go.mod h1:WUk7DtFp1Aw2MkvqGdwiXYDZZNvA/1J8o6xRXLrIkyc=
-go.opentelemetry.io/proto/otlp v1.5.0 h1:xJvq7gMzB31/d406fB8U5CBdyQGw4P399D1aQWU/3i4=
-go.opentelemetry.io/proto/otlp v1.5.0/go.mod h1:keN8WnHxOy8PG0rQZjJJ5A2ebUoafqWp0eVQ4yIXvJ4=
 go.opentelemetry.io/proto/otlp v1.7.1 h1:gTOMpGDb0WTBOP8JaO72iL3auEZhVmAQg4ipjOVAtj4=
 go.opentelemetry.io/proto/otlp v1.7.1/go.mod h1:b2rVh6rfI/s2pHWNlB7ILJcRALpcNDzKhACevjI+ZnE=
-go.uber.org/goleak v1.3.0/go.mod h1:CoHD4mav9JJNrW/WLlf7HGZPjdw8EucARQHekz1X6bE=
+golang.org/x/crypto v0.46.0/go.mod h1:Evb/oLKmMraqjZ2iQTwDwvCtJkczlDuTmdJXoZVzqU0=
+golang.org/x/mod v0.30.0/go.mod h1:lAsf5O2EvJeSFMiBxXDki7sCgAxEUcZHXoXMKT4GJKc=
 golang.org/x/net v0.35.0 h1:T5GQRQb2y08kTAByq9L4/bz8cipCdA8FbRTXewonqY8=
 golang.org/x/net v0.35.0/go.mod h1:EglIi67kWsHKlRzzVMUD93VMSWGFOMSZgxFjparz1Qk=
 golang.org/x/oauth2 v0.25.0/go.mod h1:XYTD2NtWslqkgxebSiOHnXEap4TF09sJSc7H1sXbhtI=
@@ -72,13 +57,13 @@ golang.org/x/sync v0.10.0/go.mod h1:Czt+wKu1gCyEFDUtn0jG5QVvpJ6rzVqr5aXyt9drQfk=
 golang.org/x/sync v0.19.0/go.mod h1:9KTHXmSnoGruLpwFjVSX0lNNA75CykiMECbovNTZqGI=
 golang.org/x/sys v0.30.0 h1:QjkSwP/36a20jFYWkSue1YwXzLmsV5Gfq7Eiy72C1uc=
 golang.org/x/sys v0.30.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
+golang.org/x/term v0.38.0/go.mod h1:bSEAKrOT1W+VSu9TSCMtoGEOUcKxOKgl3LE5QEF/xVg=
 golang.org/x/text v0.22.0 h1:bofq7m3/HAFvbF51jz3Q9wLg3jkvSPuiZu/pD1XwgtM=
 golang.org/x/text v0.22.0/go.mod h1:YRoo4H8PVmsu+E3Ou7cqLVH8oXWIHVoX0jqUWALQhfY=
+golang.org/x/tools v0.39.0/go.mod h1:JnefbkDPyD8UU2kI5fuf8ZX4/yUeh9W877ZeBONxUqQ=
 golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 google.golang.org/genproto/googleapis/api v0.0.0-20250218202821-56aae31c358a h1:nwKuGPlUAt+aR+pcrkfFRrTU1BVrSmYyYMxYbUIVHr0=
 google.golang.org/genproto/googleapis/api v0.0.0-20250218202821-56aae31c358a/go.mod h1:3kWAYMk1I75K4vykHtKt2ycnOgpA6974V7bREqbsenU=
-google.golang.org/genproto/googleapis/api v0.0.0-20251202230838-ff82c1b0f217 h1:fCvbg86sFXwdrl5LgVcTEvNC+2txB5mgROGmRL5mrls=
-google.golang.org/genproto/googleapis/api v0.0.0-20251202230838-ff82c1b0f217/go.mod h1:+rXWjjaukWZun3mLfjmVnQi18E1AsFbDN9QdJ5YXLto=
 google.golang.org/genproto/googleapis/rpc v0.0.0-20250218202821-56aae31c358a h1:51aaUVRocpvUOSQKM6Q7VuoaktNIaMCLuhZB6DKksq4=
 google.golang.org/genproto/googleapis/rpc v0.0.0-20250218202821-56aae31c358a/go.mod h1:uRxBH1mhmO8PGhU89cMcHaXKZqO+OfakD8QQO0oYwlQ=
 google.golang.org/grpc v1.71.0 h1:kF77BGdPTQ4/JZWMlb9VpJ5pa25aqvVqogsxNHHdeBg=
@@ -89,4 +74,4 @@ google.golang.org/protobuf v1.36.5 h1:tPhr+woSbjfYvY6/GPufUoYizxw1cF/yFoxJ2fmpwl
 google.golang.org/protobuf v1.36.5/go.mod h1:9fA7Ob0pmnwhb644+1+CVWFRbNajQ6iRojtC/QF5bRE=
 google.golang.org/protobuf v1.36.10/go.mod h1:HTf+CrKn2C3g5S8VImy6tdcUvCska2kB7j23XfzDpco=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
-gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
+gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c/go.mod h1:JHkPIbrfpd72SG/EVd6muEfDQjcINNoR0C8j2r3qZ4Q=
diff --git a/ha-gateway/cmd/gateway/main.go b/ha-gateway/cmd/gateway/main.go
index 0ae9ab7..3f6c9df 100644
--- a/ha-gateway/cmd/gateway/main.go
+++ b/ha-gateway/cmd/gateway/main.go
@@ -10,13 +10,13 @@ import (
 	"time"
 
 	"github.com/joho/godotenv"
+	"go.opentelemetry.io/contrib/instrumentation/google.golang.org/grpc/otelgrpc"
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/peer"
-	"go.opentelemetry.io/contrib/instrumentation/google.golang.org/grpc/otelgrpc"
 
 	hav1 "gitea.nik4nao.com/nik/home-services/gen/ha/v1"
-	"gitea.nik4nao.com/nik/home-services/ha-gateway/internal/adapters/secondary/ha"
 	grpcadapter "gitea.nik4nao.com/nik/home-services/ha-gateway/internal/adapters/primary/grpc"
+	"gitea.nik4nao.com/nik/home-services/ha-gateway/internal/adapters/secondary/ha"
 	"gitea.nik4nao.com/nik/home-services/ha-gateway/internal/app"
 	"gitea.nik4nao.com/nik/home-services/ha-gateway/internal/config"
 	"gitea.nik4nao.com/nik/home-services/ha-gateway/internal/telemetry"
@@ -61,6 +61,16 @@ func main() {
 	// 5. Build application services.
 	entityApp := app.NewEntityApp(haClient)
 	lightApp := app.NewLightApp(haClient)
+	switchApp := app.NewSwitchApp(haClient)
+
+	// 5a. Prime the discovery cache. Non-fatal — ListLights/ListSwitches will
+	//     retry lazily on the first call if this fails (e.g. HA not yet ready).
+	if err := lightApp.Refresh(ctx); err != nil {
+		slog.Warn("initial light discovery failed, will retry on first request", "err", err)
+	}
+	if err := switchApp.Refresh(ctx); err != nil {
+		slog.Warn("initial switch discovery failed, will retry on first request", "err", err)
+	}
 
 	// 6. Build the gRPC server with OTel stats handler and logging interceptors.
 	srv := grpc.NewServer(
@@ -72,7 +82,7 @@ func main() {
 	// 7. Register services.
 	hav1.RegisterEntityServiceServer(srv, grpcadapter.NewEntityGRPC(entityApp))
 	hav1.RegisterLightServiceServer(srv, grpcadapter.NewLightGRPC(lightApp))
-	hav1.RegisterSwitchServiceServer(srv, &grpcadapter.SwitchGRPC{})
+	hav1.RegisterSwitchServiceServer(srv, grpcadapter.NewSwitchGRPC(switchApp))
 	hav1.RegisterEventServiceServer(srv, &grpcadapter.EventGRPC{})
 
 	// 8. Start listener.
diff --git a/ha-gateway/internal/adapters/primary/grpc/entity.go b/ha-gateway/internal/adapters/primary/grpc/entity.go
index 20c45fc..1ee61c2 100644
--- a/ha-gateway/internal/adapters/primary/grpc/entity.go
+++ b/ha-gateway/internal/adapters/primary/grpc/entity.go
@@ -52,8 +52,14 @@ func grpcError(err error) error {
 	if errors.Is(err, ErrNotFound) {
 		return status.Errorf(codes.NotFound, "%v", err)
 	}
+	if errors.Is(err, ErrNotImplemented) {
+		return status.Errorf(codes.Unimplemented, "%v", err)
+	}
 	return status.Errorf(codes.Internal, "%v", err)
 }
 
 // ErrNotFound is returned by the app layer when an entity does not exist.
 var ErrNotFound = errors.New("not found")
+
+// ErrNotImplemented is returned by handlers that are stubbed pending full implementation.
+var ErrNotImplemented = errors.New("not implemented")
diff --git a/ha-gateway/internal/adapters/primary/grpc/light.go b/ha-gateway/internal/adapters/primary/grpc/light.go
index be96385..1c7e0b4 100644
--- a/ha-gateway/internal/adapters/primary/grpc/light.go
+++ b/ha-gateway/internal/adapters/primary/grpc/light.go
@@ -40,3 +40,15 @@ func (h *LightGRPC) Toggle(ctx context.Context, req *hav1.ToggleRequest) (*hav1.
 	}
 	return &hav1.LightResponse{State: domainStateToProto(s)}, nil
 }
+
+func (h *LightGRPC) ListLights(ctx context.Context, req *hav1.ListLightsRequest) (*hav1.ListLightsResponse, error) {
+	lights, err := h.svc.ListLights(ctx)
+	if err != nil {
+		return nil, grpcError(err)
+	}
+	out := make([]*hav1.LightEntity, 0, len(lights))
+	for _, l := range lights {
+		out = append(out, domainLightToProto(l))
+	}
+	return &hav1.ListLightsResponse{Lights: out}, nil
+}
diff --git a/ha-gateway/internal/adapters/primary/grpc/mapping.go b/ha-gateway/internal/adapters/primary/grpc/mapping.go
index 8e7755e..b272040 100644
--- a/ha-gateway/internal/adapters/primary/grpc/mapping.go
+++ b/ha-gateway/internal/adapters/primary/grpc/mapping.go
@@ -1,8 +1,8 @@
 package grpc
 
 import (
-	"gitea.nik4nao.com/nik/home-services/ha-gateway/internal/core/domain"
 	hav1 "gitea.nik4nao.com/nik/home-services/gen/ha/v1"
+	"gitea.nik4nao.com/nik/home-services/ha-gateway/internal/core/domain"
 )
 
 func domainStateToProto(s *domain.EntityState) *hav1.EntityState {
@@ -51,3 +51,29 @@ func protoTurnOffToParams(r *hav1.TurnOffRequest) domain.TurnOffParams {
 	}
 	return p
 }
+
+func domainLightToProto(l domain.Light) *hav1.LightEntity {
+	modes := make([]string, len(l.SupportedColorModes))
+	for i, m := range l.SupportedColorModes {
+		modes[i] = string(m)
+	}
+	return &hav1.LightEntity{
+		EntityId:            string(l.EntityID),
+		FriendlyName:        l.FriendlyName,
+		State:               l.State,
+		SupportedColorModes: modes,
+		MinColorTempKelvin:  l.MinColorTempKelvin,
+		MaxColorTempKelvin:  l.MaxColorTempKelvin,
+		IsHueGroup:          l.IsHueGroup,
+		EffectList:          l.EffectList,
+	}
+}
+
+func domainSwitchToProto(s domain.Switch) *hav1.SwitchEntity {
+	return &hav1.SwitchEntity{
+		EntityId:     string(s.EntityID),
+		FriendlyName: s.FriendlyName,
+		State:        s.State,
+		DeviceClass:  s.DeviceClass,
+	}
+}
diff --git a/ha-gateway/internal/adapters/primary/grpc/switch.go b/ha-gateway/internal/adapters/primary/grpc/switch.go
index 2b2e559..677c9b4 100644
--- a/ha-gateway/internal/adapters/primary/grpc/switch.go
+++ b/ha-gateway/internal/adapters/primary/grpc/switch.go
@@ -1,12 +1,44 @@
 package grpc
 
 import (
+	"context"
+
 	hav1 "gitea.nik4nao.com/nik/home-services/gen/ha/v1"
+	"gitea.nik4nao.com/nik/home-services/ha-gateway/internal/core/ports/driving"
 )
 
 type SwitchGRPC struct {
 	hav1.UnimplementedSwitchServiceServer
+	svc driving.SwitchService
 }
 
-// All methods return codes.Unimplemented via the embedded UnimplementedSwitchServiceServer.
-// TODO: follow the same pattern as LightGRPC once app/switch.go is implemented.
+func NewSwitchGRPC(svc driving.SwitchService) *SwitchGRPC {
+	return &SwitchGRPC{svc: svc}
+}
+
+func (h *SwitchGRPC) ListSwitches(ctx context.Context, req *hav1.ListSwitchesRequest) (*hav1.ListSwitchesResponse, error) {
+	switches, err := h.svc.ListSwitches(ctx)
+	if err != nil {
+		return nil, grpcError(err)
+	}
+	out := make([]*hav1.SwitchEntity, 0, len(switches))
+	for _, s := range switches {
+		out = append(out, domainSwitchToProto(s))
+	}
+	return &hav1.ListSwitchesResponse{Switches: out}, nil
+}
+
+// TurnOn, TurnOff, Toggle — left as Unimplemented for now.
+// TODO: implement once app/switch.go has callService support.
+// Follow the same pattern as LightGRPC: payload{"entity_id": ...} → ha.CallService.
+func (h *SwitchGRPC) TurnOn(ctx context.Context, req *hav1.SwitchRequest) (*hav1.SwitchResponse, error) {
+	return nil, grpcError(ErrNotImplemented)
+}
+
+func (h *SwitchGRPC) TurnOff(ctx context.Context, req *hav1.SwitchRequest) (*hav1.SwitchResponse, error) {
+	return nil, grpcError(ErrNotImplemented)
+}
+
+func (h *SwitchGRPC) Toggle(ctx context.Context, req *hav1.SwitchRequest) (*hav1.SwitchResponse, error) {
+	return nil, grpcError(ErrNotImplemented)
+}
diff --git a/ha-gateway/internal/app/light.go b/ha-gateway/internal/app/light.go
index 11dd2d6..bbb0f4d 100644
--- a/ha-gateway/internal/app/light.go
+++ b/ha-gateway/internal/app/light.go
@@ -2,19 +2,58 @@ package app
 
 import (
 	"context"
+	"strings"
+	"sync"
 
 	"gitea.nik4nao.com/nik/home-services/ha-gateway/internal/core/domain"
 	"gitea.nik4nao.com/nik/home-services/ha-gateway/internal/core/ports/driven"
 )
 
 type LightApp struct {
-	ha driven.HAClient
+	ha    driven.HAClient
+	mu    sync.RWMutex
+	cache []domain.Light
 }
 
 func NewLightApp(ha driven.HAClient) *LightApp {
 	return &LightApp{ha: ha}
 }
 
+func (a *LightApp) Refresh(ctx context.Context) error {
+	all, err := a.ha.ListStates(ctx)
+	if err != nil {
+		return err
+	}
+
+	var lights []domain.Light
+	for _, s := range all {
+		if !strings.HasPrefix(s.EntityID, "light.") {
+			continue
+		}
+		lights = append(lights, haStateToLight(s))
+	}
+
+	a.mu.Lock()
+	a.cache = lights
+	a.mu.Unlock()
+	return nil
+}
+
+func (a *LightApp) ListLights(ctx context.Context) ([]domain.Light, error) {
+	a.mu.RLock()
+	c := a.cache
+	a.mu.RUnlock()
+	if c == nil {
+		if err := a.Refresh(ctx); err != nil {
+			return nil, err
+		}
+		a.mu.RLock()
+		c = a.cache
+		a.mu.RUnlock()
+	}
+	return c, nil
+}
+
 func (a *LightApp) TurnOn(ctx context.Context, p domain.TurnOnParams) (*domain.EntityState, error) {
 	payload := map[string]any{"entity_id": string(p.EntityID)}
 	if p.BrightnessPct != nil {
@@ -63,3 +102,39 @@ func (a *LightApp) callService(ctx context.Context, svcDomain, service string, p
 	}
 	return haStateToDomain(s), nil
 }
+
+func haStateToLight(s *driven.HAState) domain.Light {
+	l := domain.Light{
+		EntityID: domain.EntityID(s.EntityID),
+		State:    s.State,
+	}
+
+	if v, ok := s.Attributes["friendly_name"].(string); ok {
+		l.FriendlyName = v
+	}
+	if v, ok := s.Attributes["is_hue_group"].(bool); ok {
+		l.IsHueGroup = v
+	}
+	if v, ok := s.Attributes["min_color_temp_kelvin"].(float64); ok {
+		l.MinColorTempKelvin = uint32(v)
+	}
+	if v, ok := s.Attributes["max_color_temp_kelvin"].(float64); ok {
+		l.MaxColorTempKelvin = uint32(v)
+	}
+	if modes, ok := s.Attributes["supported_color_modes"].([]any); ok {
+		for _, m := range modes {
+			if ms, ok := m.(string); ok {
+				l.SupportedColorModes = append(l.SupportedColorModes, domain.ColorMode(ms))
+			}
+		}
+	}
+	if effects, ok := s.Attributes["effect_list"].([]any); ok {
+		for _, e := range effects {
+			if es, ok := e.(string); ok {
+				l.EffectList = append(l.EffectList, es)
+			}
+		}
+	}
+
+	return l
+}
diff --git a/ha-gateway/internal/app/switch.go b/ha-gateway/internal/app/switch.go
new file mode 100644
index 0000000..b8b942f
--- /dev/null
+++ b/ha-gateway/internal/app/switch.go
@@ -0,0 +1,69 @@
+package app
+
+import (
+	"context"
+	"strings"
+	"sync"
+
+	"gitea.nik4nao.com/nik/home-services/ha-gateway/internal/core/domain"
+	"gitea.nik4nao.com/nik/home-services/ha-gateway/internal/core/ports/driven"
+)
+
+type SwitchApp struct {
+	ha    driven.HAClient
+	mu    sync.RWMutex
+	cache []domain.Switch
+}
+
+func NewSwitchApp(ha driven.HAClient) *SwitchApp {
+	return &SwitchApp{ha: ha}
+}
+
+func (a *SwitchApp) Refresh(ctx context.Context) error {
+	all, err := a.ha.ListStates(ctx)
+	if err != nil {
+		return err
+	}
+
+	var switches []domain.Switch
+	for _, s := range all {
+		if !strings.HasPrefix(s.EntityID, "switch.") {
+			continue
+		}
+		switches = append(switches, haStateToSwitch(s))
+	}
+
+	a.mu.Lock()
+	a.cache = switches
+	a.mu.Unlock()
+	return nil
+}
+
+func (a *SwitchApp) ListSwitches(ctx context.Context) ([]domain.Switch, error) {
+	a.mu.RLock()
+	c := a.cache
+	a.mu.RUnlock()
+	if c == nil {
+		if err := a.Refresh(ctx); err != nil {
+			return nil, err
+		}
+		a.mu.RLock()
+		c = a.cache
+		a.mu.RUnlock()
+	}
+	return c, nil
+}
+
+func haStateToSwitch(s *driven.HAState) domain.Switch {
+	sw := domain.Switch{
+		EntityID: domain.EntityID(s.EntityID),
+		State:    s.State,
+	}
+	if v, ok := s.Attributes["friendly_name"].(string); ok {
+		sw.FriendlyName = v
+	}
+	if v, ok := s.Attributes["device_class"].(string); ok {
+		sw.DeviceClass = v
+	}
+	return sw
+}
diff --git a/ha-gateway/internal/core/domain/entity.go b/ha-gateway/internal/core/domain/entity.go
index b9fed0c..3caf677 100644
--- a/ha-gateway/internal/core/domain/entity.go
+++ b/ha-gateway/internal/core/domain/entity.go
@@ -1,6 +1,9 @@
 package domain
 
-import "time"
+import (
+	"errors"
+	"time"
+)
 
 type EntityID string
 
@@ -11,3 +14,5 @@ type EntityState struct {
 	LastChanged time.Time
 	LastUpdated time.Time
 }
+
+var ErrNotImplemented = errors.New("not implemented")
diff --git a/ha-gateway/internal/core/domain/light.go b/ha-gateway/internal/core/domain/light.go
index 7c36b09..9384745 100644
--- a/ha-gateway/internal/core/domain/light.go
+++ b/ha-gateway/internal/core/domain/light.go
@@ -1,8 +1,28 @@
 package domain
 
+type ColorMode string
+
+const (
+	ColorModeColorTemp  ColorMode = "color_temp"
+	ColorModeHS         ColorMode = "hs"
+	ColorModeXY         ColorMode = "xy"
+	ColorModeBrightness ColorMode = "brightness"
+)
+
+type Light struct {
+	EntityID            EntityID
+	FriendlyName        string
+	State               string // "on" | "off" | "unavailable"
+	SupportedColorModes []ColorMode
+	MinColorTempKelvin  uint32
+	MaxColorTempKelvin  uint32
+	IsHueGroup          bool
+	EffectList          []string
+}
+
 type TurnOnParams struct {
 	EntityID        EntityID
-	BrightnessPct   *uint32 // nil = not set
+	BrightnessPct   *uint32
 	ColorTempKelvin *uint32
 	RGBColor        *RGBColor
 	Transition      *uint32
diff --git a/ha-gateway/internal/core/domain/switch.go b/ha-gateway/internal/core/domain/switch.go
new file mode 100644
index 0000000..3357e18
--- /dev/null
+++ b/ha-gateway/internal/core/domain/switch.go
@@ -0,0 +1,8 @@
+package domain
+
+type Switch struct {
+	EntityID     EntityID
+	FriendlyName string
+	State        string // "on" | "off" | "unavailable"
+	DeviceClass  string // e.g. "switch"
+}
diff --git a/ha-gateway/internal/core/ports/driving/light.go b/ha-gateway/internal/core/ports/driving/light.go
index 3d22410..99364b9 100644
--- a/ha-gateway/internal/core/ports/driving/light.go
+++ b/ha-gateway/internal/core/ports/driving/light.go
@@ -10,4 +10,6 @@ type LightService interface {
 	TurnOn(ctx context.Context, p domain.TurnOnParams) (*domain.EntityState, error)
 	TurnOff(ctx context.Context, p domain.TurnOffParams) (*domain.EntityState, error)
 	Toggle(ctx context.Context, id domain.EntityID) (*domain.EntityState, error)
+	ListLights(ctx context.Context) ([]domain.Light, error)
+	Refresh(ctx context.Context) error
 }
diff --git a/ha-gateway/internal/core/ports/driving/switch.go b/ha-gateway/internal/core/ports/driving/switch.go
new file mode 100644
index 0000000..22fff89
--- /dev/null
+++ b/ha-gateway/internal/core/ports/driving/switch.go
@@ -0,0 +1,12 @@
+package driving
+
+import (
+	"context"
+
+	"gitea.nik4nao.com/nik/home-services/ha-gateway/internal/core/domain"
+)
+
+type SwitchService interface {
+	ListSwitches(ctx context.Context) ([]domain.Switch, error)
+	Refresh(ctx context.Context) error
+}
diff --git a/proto/ha/v1/light.proto b/proto/ha/v1/light.proto
index 2d59290..914f5c3 100644
--- a/proto/ha/v1/light.proto
+++ b/proto/ha/v1/light.proto
@@ -7,6 +7,7 @@ service LightService {
   rpc TurnOn(TurnOnRequest)   returns (LightResponse);
   rpc TurnOff(TurnOffRequest) returns (LightResponse);
   rpc Toggle(ToggleRequest)   returns (LightResponse);
+  rpc ListLights(ListLightsRequest) returns (ListLightsResponse);
 }
 
 // optional fields require protobuf 3.15+ / buf >= 1.0. They generate
@@ -25,3 +26,19 @@ message TurnOffRequest {
 }
 message ToggleRequest { string entity_id = 1; }
 message LightResponse { EntityState state = 1; }
+message LightEntity {
+  string entity_id = 1;
+  string friendly_name = 2;
+  string state = 3;
+  repeated string supported_color_modes = 4;
+  uint32 min_color_temp_kelvin = 5;
+  uint32 max_color_temp_kelvin = 6;
+  bool is_hue_group = 7;
+  repeated string effect_list = 8;
+}
+
+message ListLightsRequest {}
+
+message ListLightsResponse {
+  repeated LightEntity lights = 1;
+}
diff --git a/proto/ha/v1/switch.proto b/proto/ha/v1/switch.proto
index 4d38d80..8fb6582 100644
--- a/proto/ha/v1/switch.proto
+++ b/proto/ha/v1/switch.proto
@@ -3,16 +3,25 @@ package ha.v1;
 option go_package = "gitea.nik4nao.com/nik/home-services/gen/ha/v1;hav1";
 import "ha/v1/common.proto";
 
-// TODO: implement SwitchService. Follow the same pattern as LightService:
-// - domain type in core/domain/switch.go
-// - port interface in core/ports/driving/switch.go
-// - application logic in app/switch.go
-// - gRPC adapter in adapters/primary/grpc/switch.go
 service SwitchService {
-  rpc TurnOn(SwitchRequest)  returns (SwitchResponse);
-  rpc TurnOff(SwitchRequest) returns (SwitchResponse);
-  rpc Toggle(SwitchRequest)  returns (SwitchResponse);
+  rpc TurnOn(SwitchRequest)             returns (SwitchResponse);
+  rpc TurnOff(SwitchRequest)            returns (SwitchResponse);
+  rpc Toggle(SwitchRequest)             returns (SwitchResponse);
+  rpc ListSwitches(ListSwitchesRequest) returns (ListSwitchesResponse);
 }
 
 message SwitchRequest  { string entity_id = 1; }
 message SwitchResponse { EntityState state = 1; }
+
+message SwitchEntity {
+  string entity_id     = 1;
+  string friendly_name = 2;
+  string state         = 3;
+  string device_class  = 4;
+}
+
+message ListSwitchesRequest {}
+
+message ListSwitchesResponse {
+  repeated SwitchEntity switches = 1;
+}
\ No newline at end of file