feat(chatd): set User-Agent on all outgoing LLM requests (#22965)

coderd/chatd/chatd.go

@@ -2852,7 +2852,7 @@ func (p *Server) resolveChatModel(
 	)
 
 	model, err := chatprovider.ModelFromConfig(
-		dbConfig.Provider, dbConfig.Model, keys,
+		dbConfig.Provider, dbConfig.Model, keys, chatprovider.UserAgent(),
 	)
 	if err != nil {
 		return nil, database.ChatModelConfig{}, chatprovider.ProviderAPIKeys{}, xerrors.Errorf(

coderd/chatd/chatprovider/chatprovider.go

@@ -916,11 +916,14 @@ func MergeMissingProviderOptions(
 }
 
 // ModelFromConfig resolves a provider/model pair and constructs a fantasy
-// language model client using the provided provider credentials.
+// language model client using the provided provider credentials. The
+// userAgent is sent as the User-Agent header on every outgoing LLM
+// API request.
 func ModelFromConfig(
 	providerHint string,
 	modelName string,
 	providerKeys ProviderAPIKeys,
+	userAgent string,
 ) (fantasy.LanguageModel, error) {
 	provider, modelID, err := ResolveModelWithProviderHint(modelName, providerHint)
 	if err != nil {
@@ -938,6 +941,7 @@ func ModelFromConfig(
 	case fantasyanthropic.Name:
 		options := []fantasyanthropic.Option{
 			fantasyanthropic.WithAPIKey(apiKey),
+			fantasyanthropic.WithUserAgent(userAgent),
 		}
 		if baseURL != "" {
 			options = append(options, fantasyanthropic.WithBaseURL(baseURL))
@@ -951,12 +955,17 @@ func ModelFromConfig(
 			fantasyazure.WithAPIKey(apiKey),
 			fantasyazure.WithBaseURL(baseURL),
 			fantasyazure.WithUseResponsesAPI(),
+			fantasyazure.WithUserAgent(userAgent),
 		)
 	case fantasybedrock.Name:
-		providerClient, err = fantasybedrock.New(fantasybedrock.WithAPIKey(apiKey))
+		providerClient, err = fantasybedrock.New(
+			fantasybedrock.WithAPIKey(apiKey),
+			fantasybedrock.WithUserAgent(userAgent),
+		)
 	case fantasygoogle.Name:
 		options := []fantasygoogle.Option{
 			fantasygoogle.WithGeminiAPIKey(apiKey),
+			fantasygoogle.WithUserAgent(userAgent),
 		}
 		if baseURL != "" {
 			options = append(options, fantasygoogle.WithBaseURL(baseURL))
@@ -966,6 +975,7 @@ func ModelFromConfig(
 		options := []fantasyopenai.Option{
 			fantasyopenai.WithAPIKey(apiKey),
 			fantasyopenai.WithUseResponsesAPI(),
+			fantasyopenai.WithUserAgent(userAgent),
 		}
 		if baseURL != "" {
 			options = append(options, fantasyopenai.WithBaseURL(baseURL))
@@ -974,16 +984,21 @@ func ModelFromConfig(
 	case fantasyopenaicompat.Name:
 		options := []fantasyopenaicompat.Option{
 			fantasyopenaicompat.WithAPIKey(apiKey),
+			fantasyopenaicompat.WithUserAgent(userAgent),
 		}
 		if baseURL != "" {
 			options = append(options, fantasyopenaicompat.WithBaseURL(baseURL))
 		}
 		providerClient, err = fantasyopenaicompat.New(options...)
 	case fantasyopenrouter.Name:
-		providerClient, err = fantasyopenrouter.New(fantasyopenrouter.WithAPIKey(apiKey))
+		providerClient, err = fantasyopenrouter.New(
+			fantasyopenrouter.WithAPIKey(apiKey),
+			fantasyopenrouter.WithUserAgent(userAgent),
+		)
 	case fantasyvercel.Name:
 		options := []fantasyvercel.Option{
 			fantasyvercel.WithAPIKey(apiKey),
+			fantasyvercel.WithUserAgent(userAgent),
 		}
 		if baseURL != "" {
 			options = append(options, fantasyvercel.WithBaseURL(baseURL))

coderd/chatd/chatprovider/useragent.go

@@ -0,0 +1,19 @@
+package chatprovider
+
+import (
+	"fmt"
+	"runtime"
+
+	"github.com/coder/coder/v2/buildinfo"
+)
+
+// UserAgent returns the User-Agent string sent on all outgoing LLM
+// API requests made by Coder's built-in chat (chatd). The format
+// mirrors conventions used by other coding agents so that LLM
+// providers can identify traffic originating from Coder.
+//
+// Example: coder-agents/v2.21.0 (linux/amd64)
+func UserAgent() string {
+	return fmt.Sprintf("coder-agents/%s (%s/%s)",
+		buildinfo.Version(), runtime.GOOS, runtime.GOARCH)
+}

coderd/chatd/chatprovider/useragent_test.go

@@ -0,0 +1,78 @@
+package chatprovider_test
+
+import (
+	"context"
+	"runtime"
+	"strings"
+	"sync"
+	"testing"
+
+	"charm.land/fantasy"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
+	"github.com/coder/coder/v2/buildinfo"
+	"github.com/coder/coder/v2/coderd/chatd/chatprovider"
+	"github.com/coder/coder/v2/coderd/chatd/chattest"
+)
+
+func TestUserAgent(t *testing.T) {
+	t.Parallel()
+	ua := chatprovider.UserAgent()
+
+	// Must start with "coder-agents/" so LLM providers can
+	// identify traffic from Coder.
+	require.True(t, strings.HasPrefix(ua, "coder-agents/"),
+		"User-Agent should start with 'coder-agents/', got %q", ua)
+
+	// Must contain the build version.
+	assert.Contains(t, ua, buildinfo.Version())
+
+	// Must contain OS/arch.
+	assert.Contains(t, ua, runtime.GOOS+"/"+runtime.GOARCH)
+}
+
+func TestModelFromConfig_UserAgent(t *testing.T) {
+	t.Parallel()
+
+	var mu sync.Mutex
+	var capturedUA string
+
+	serverURL := chattest.NewOpenAI(t, func(req *chattest.OpenAIRequest) chattest.OpenAIResponse {
+		mu.Lock()
+		capturedUA = req.Header.Get("User-Agent")
+		mu.Unlock()
+		return chattest.OpenAINonStreamingResponse("hello")
+	})
+
+	expectedUA := chatprovider.UserAgent()
+	keys := chatprovider.ProviderAPIKeys{
+		ByProvider:        map[string]string{"openai": "test-key"},
+		BaseURLByProvider: map[string]string{"openai": serverURL},
+	}
+
+	model, err := chatprovider.ModelFromConfig("openai", "gpt-4", keys, expectedUA)
+	require.NoError(t, err)
+
+	// Make a real call so Fantasy sends an HTTP request to the
+	// fake server, which captures the User-Agent header.
+	_, err = model.Generate(context.Background(), fantasy.Call{
+		Prompt: []fantasy.Message{
+			{
+				Role: fantasy.MessageRoleUser,
+				Content: []fantasy.MessagePart{
+					fantasy.TextPart{Text: "hello"},
+				},
+			},
+		},
+	})
+	require.NoError(t, err)
+
+	mu.Lock()
+	got := capturedUA
+	mu.Unlock()
+
+	require.NotEmpty(t, got, "User-Agent header was not sent")
+	require.Equal(t, expectedUA, got,
+		"User-Agent header should match chatprovider.UserAgent()")
+}

coderd/chatd/quickgen.go

@@ -76,7 +76,7 @@ func (p *Server) maybeGenerateChatTitle(
 	candidates := make([]fantasy.LanguageModel, 0, len(preferredTitleModels)+1)
 	for _, c := range preferredTitleModels {
 		m, err := chatprovider.ModelFromConfig(
-			c.provider, c.model, keys,
+			c.provider, c.model, keys, chatprovider.UserAgent(),
 		)
 		if err == nil {
 			candidates = append(candidates, m)
@@ -281,7 +281,7 @@ func generatePushSummary(
 	candidates := make([]fantasy.LanguageModel, 0, len(preferredTitleModels)+1)
 	for _, c := range preferredTitleModels {
 		m, err := chatprovider.ModelFromConfig(
-			c.provider, c.model, keys,
+			c.provider, c.model, keys, chatprovider.UserAgent(),
 		)
 		if err == nil {
 			candidates = append(candidates, m)