refactor(handler): move error conversion to the handler

controller/BUILD.bazel

@@ -5,7 +5,6 @@ go_library(
     srcs = [
         "controller.go",
         "distance_filter.go",
-        "errors.go",
         "getchangedtargetgraph.go",
         "getchangedtargets.go",
         "gettargetgraph.go",
@@ -48,7 +47,6 @@ go_test(
         "metrics_test.go",
         "output_filter_test.go",
         "testhelper_test.go",
-        "wireerror_test.go",
     ],
     embed = [":controller"],
     deps = [
@@ -66,8 +64,6 @@ go_test(
         "@com_github_stretchr_testify//require",
         "@com_github_uber_go_tally//:tally",
         "@org_uber_go_mock//gomock",
-        "@org_uber_go_yarpc//encoding/protobuf",
-        "@org_uber_go_yarpc//yarpcerrors",
         "@org_uber_go_zap//:zap",
         "@org_uber_go_zap//zaptest",
     ],

controller/getchangedtargets.go

@@ -95,10 +95,6 @@ func (c *controller) GetChangedTargets(request *pb.GetChangedTargetsRequest, str
 	)
 	defer func() {
 		op.Complete(retErr)
-		if retErr != nil {
-			logger.Error("GetChangedTargets failed", tangoerrors.Fields(retErr)...)
-			retErr = toWireError(retErr)
-		}
 	}()
 	if repositoryErr != nil {
 		return repositoryErr

controller/gettargetgraph.go

@@ -47,10 +47,6 @@ func (c *controller) GetTargetGraph(request *pb.GetTargetGraphRequest, stream pb
 	)
 	defer func() {
 		op.Complete(retErr)
-		if retErr != nil {
-			logger.Error("GetTargetGraph failed", tangoerrors.Fields(retErr)...)
-			retErr = toWireError(retErr)
-		}
 	}()
 	start := time.Now()
 	ctx, cancelLink := c.linkRequestCtx(stream.Context())

example/main.go

@@ -109,7 +109,7 @@ func run() error {
 		GraphConfig:     cfg,
 	})
 
-	h := handler.New(handler.Params{Controller: ctrl})
+	h := handler.New(handler.Params{Logger: logger, Controller: ctrl})
 
 	// YARPC transports and dispatcher
 	grpcTransport := yarpcgrpc.NewTransport()

handler/BUILD.bazel

@@ -3,6 +3,7 @@ load("@rules_go//go:def.bzl", "go_library", "go_test")
 go_library(
     name = "handler",
     srcs = [
+        "errors.go",
         "getchangedtargetgraph.go",
         "getchangedtargets.go",
         "gettargetgraph.go",
@@ -12,7 +13,10 @@ go_library(
     visibility = ["//visibility:public"],
     deps = [
         "//controller",
+        "//core/errors",
+        "//mapper/proto",
         "//tangopb",
+        "@org_uber_go_zap//:zap",
     ],
 )
 
@@ -22,13 +26,24 @@ go_test(
         "getchangedtargetgraph_test.go",
         "getchangedtargets_test.go",
         "gettargetgraph_test.go",
+        "testhelper_test.go",
+        "wireerror_test.go",
     ],
     embed = [":handler"],
     deps = [
+        "//config",
+        "//controller",
         "//controller/controllermock",
+        "//core/errors",
+        "//core/storage",
+        "//core/storage/storagemock",
         "//tangopb",
+        "//tangopb/tangopbmock",
         "@com_github_stretchr_testify//assert",
         "@com_github_stretchr_testify//require",
         "@org_uber_go_mock//gomock",
+        "@org_uber_go_yarpc//encoding/protobuf",
+        "@org_uber_go_yarpc//yarpcerrors",
+        "@org_uber_go_zap//zaptest",
     ],
 )

controller/errors.go → handler/errors.go

@@ -12,7 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-package controller
+package handler
 
 import (
 	"github.com/uber/tango/mapper/proto"

handler/getchangedtargets.go

@@ -15,9 +15,16 @@
 package handler
 
 import (
+	tangoerrors "github.com/uber/tango/core/errors"
 	pb "github.com/uber/tango/tangopb"
 )
 
-func (h *handler) GetChangedTargets(request *pb.GetChangedTargetsRequest, stream pb.TangoServiceGetChangedTargetsYARPCServer) error {
+func (h *handler) GetChangedTargets(request *pb.GetChangedTargetsRequest, stream pb.TangoServiceGetChangedTargetsYARPCServer) (retErr error) {
+	defer func() {
+		if retErr != nil {
+			h.logger.Error("GetChangedTargets failed", tangoerrors.Fields(retErr)...)
+			retErr = toWireError(retErr)
+		}
+	}()
 	return h.controller.GetChangedTargets(request, stream)
 }

handler/getchangedtargets_test.go

@@ -22,6 +22,7 @@ import (
 	mock_controller "github.com/uber/tango/controller/controllermock"
 	pb "github.com/uber/tango/tangopb"
 	"go.uber.org/mock/gomock"
+	"go.uber.org/zap/zaptest"
 )
 
 type fakeGetChangedTargetsStream struct {
@@ -30,7 +31,7 @@ type fakeGetChangedTargetsStream struct {
 
 func TestGetChangedTargetsForwardsToController(t *testing.T) {
 	ctrl := mock_controller.NewMockController(gomock.NewController(t))
-	h := New(Params{Controller: ctrl})
+	h := New(Params{Logger: zaptest.NewLogger(t), Controller: ctrl})
 
 	req := &pb.GetChangedTargetsRequest{}
 	stream := &fakeGetChangedTargetsStream{}

handler/gettargetgraph.go

@@ -15,9 +15,16 @@
 package handler
 
 import (
+	tangoerrors "github.com/uber/tango/core/errors"
 	pb "github.com/uber/tango/tangopb"
 )
 
-func (h *handler) GetTargetGraph(request *pb.GetTargetGraphRequest, stream pb.TangoServiceGetTargetGraphYARPCServer) error {
+func (h *handler) GetTargetGraph(request *pb.GetTargetGraphRequest, stream pb.TangoServiceGetTargetGraphYARPCServer) (retErr error) {
+	defer func() {
+		if retErr != nil {
+			h.logger.Error("GetTargetGraph failed", tangoerrors.Fields(retErr)...)
+			retErr = toWireError(retErr)
+		}
+	}()
 	return h.controller.GetTargetGraph(request, stream)
 }

handler/gettargetgraph_test.go

@@ -22,6 +22,7 @@ import (
 	mock_controller "github.com/uber/tango/controller/controllermock"
 	pb "github.com/uber/tango/tangopb"
 	"go.uber.org/mock/gomock"
+	"go.uber.org/zap/zaptest"
 )
 
 type fakeGetTargetGraphStream struct {
@@ -30,7 +31,7 @@ type fakeGetTargetGraphStream struct {
 
 func TestGetTargetGraphForwardsToController(t *testing.T) {
 	ctrl := mock_controller.NewMockController(gomock.NewController(t))
-	h := New(Params{Controller: ctrl})
+	h := New(Params{Logger: zaptest.NewLogger(t), Controller: ctrl})
 
 	req := &pb.GetTargetGraphRequest{}
 	stream := &fakeGetTargetGraphStream{}

handler/handler.go

@@ -17,16 +17,19 @@ package handler
 import (
 	"github.com/uber/tango/controller"
 	pb "github.com/uber/tango/tangopb"
+	"go.uber.org/zap"
 )
 
 type Params struct {
+	Logger     *zap.Logger
 	Controller controller.Controller
 }
 
 type handler struct {
+	logger     *zap.Logger
 	controller controller.Controller
 }
 
 func New(p Params) pb.TangoYARPCServer {
-	return &handler{controller: p.Controller}
+	return &handler{logger: p.Logger, controller: p.Controller}
 }

handler/testhelper_test.go

@@ -0,0 +1,28 @@
+// Copyright (c) 2026 Uber Technologies, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package handler
+
+import "github.com/uber/tango/config"
+
+// allowAnyRepositoryConfigProvider resolves every remote to a fixed
+// repository, mirroring the stub of the same name in controller's tests.
+type allowAnyRepositoryConfigProvider struct{}
+
+func (allowAnyRepositoryConfigProvider) GetRepositoryConfig(remote string) (config.RepositoryConfig, bool) {
+	return config.RepositoryConfig{
+		Remote:       remote,
+		RepositoryID: "test-repository",
+	}, true
+}

controller/wireerror_test.go → handler/wireerror_test.go

@@ -12,7 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-package controller
+package handler
 
 import (
 	"context"
@@ -21,6 +21,7 @@ import (
 
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
+	"github.com/uber/tango/controller"
 	tangoerrors "github.com/uber/tango/core/errors"
 	"github.com/uber/tango/core/storage"
 	storagemock "github.com/uber/tango/core/storage/storagemock"
@@ -88,10 +89,10 @@ func TestGetTargetGraph_ValidationError_WiresTangoError(t *testing.T) {
 	stream := tangomock.NewMockTangoServiceGetTargetGraphYARPCServer(ctrl)
 	stream.EXPECT().Context().Return(context.Background())
 
-	c := NewController(context.Background(), Params{
+	c := New(Params{Logger: zaptest.NewLogger(t), Controller: controller.NewController(context.Background(), controller.Params{
 		RepoConfig: allowAnyRepositoryConfigProvider{},
 		Logger:     zaptest.NewLogger(t),
-	})
+	})})
 
 	// Missing BaseSha triggers a validation error classified as ERROR_USER.
 	err := c.GetTargetGraph(&pb.GetTargetGraphRequest{
@@ -117,10 +118,10 @@ func TestGetChangedTargets_ValidationError_WiresTangoError(t *testing.T) {
 	stream := tangomock.NewMockTangoServiceGetChangedTargetsYARPCServer(ctrl)
 	stream.EXPECT().Context().Return(context.Background()).AnyTimes()
 
-	c := NewController(context.Background(), Params{
+	c := New(Params{Logger: zaptest.NewLogger(t), Controller: controller.NewController(context.Background(), controller.Params{
 		RepoConfig: allowAnyRepositoryConfigProvider{},
 		Logger:     zaptest.NewLogger(t),
-	})
+	})})
 
 	// Missing first revision triggers validation error classified as ERROR_USER.
 	err := c.GetChangedTargets(&pb.GetChangedTargetsRequest{
@@ -146,11 +147,11 @@ func TestGetTargetGraph_InfraError_WiresTangoError(t *testing.T) {
 	store := storagemock.NewMockStorage(ctrl)
 	store.EXPECT().Get(gomock.Any(), gomock.Any()).Return(storage.DownloadResponse{}, errors.New("disk on fire"))
 
-	c := NewController(context.Background(), Params{
+	c := New(Params{Logger: zaptest.NewLogger(t), Controller: controller.NewController(context.Background(), controller.Params{
 		RepoConfig: allowAnyRepositoryConfigProvider{},
 		Logger:     zaptest.NewLogger(t),
 		Storage:    store,
-	})
+	})})
 
 	err := c.GetTargetGraph(&pb.GetTargetGraphRequest{
 		BuildDescription: &pb.BuildDescription{

integration/integration_test.go

@@ -156,7 +156,7 @@ func startServerWithLogger(t testing.TB, remote string, zl *zap.Logger) string {
 		GraphConfig:  cfg,
 	})
 
-	h := handler.New(handler.Params{Controller: ctrl})
+	h := handler.New(handler.Params{Logger: zl, Controller: ctrl})
 
 	grpcTransport := yarpcgrpc.NewTransport()
 	listener, err := net.Listen("tcp", "127.0.0.1:0")