feat: add source identifier to API requests for telemetry

internal/api/client.go

@@ -200,6 +200,11 @@ func (c *Client) baseURL() string {
 
 func (c *Client) get(ctx context.Context, path string, result any) error {
 	url := c.baseURL() + path
+	if strings.Contains(path, "?") {
+		url += "&source=cli"
+	} else {
+		url += "?source=cli"
+	}
 
 	req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
 	if err != nil {

internal/api/client_test.go

@@ -356,6 +356,36 @@ func TestRetryAfterInvalidFallback(t *testing.T) {
 	assert.ErrorIs(t, err, ErrRateLimited)
 }
 
+func TestSourceCLIAppendedWithoutExistingQuery(t *testing.T) {
+	var gotSource string
+	c, srv := testClient(func(w http.ResponseWriter, r *http.Request) {
+		gotSource = r.URL.Query().Get("source")
+		w.WriteHeader(200)
+		_, _ = w.Write([]byte("{}"))
+	})
+	defer srv.Close()
+
+	var result map[string]any
+	_ = c.get(context.Background(), "/test", &result)
+	assert.Equal(t, "cli", gotSource)
+}
+
+func TestSourceCLIAppendedWithExistingQuery(t *testing.T) {
+	var gotSource, gotExisting string
+	c, srv := testClient(func(w http.ResponseWriter, r *http.Request) {
+		gotSource = r.URL.Query().Get("source")
+		gotExisting = r.URL.Query().Get("foo")
+		w.WriteHeader(200)
+		_, _ = w.Write([]byte("{}"))
+	})
+	defer srv.Close()
+
+	var result map[string]any
+	_ = c.get(context.Background(), "/test?foo=bar", &result)
+	assert.Equal(t, "cli", gotSource)
+	assert.Equal(t, "bar", gotExisting)
+}
+
 func TestRequirePaid(t *testing.T) {
 	cfg := &config.Config{Tier: config.TierDemo}
 	c := NewClient(cfg)

internal/ws/client.go

@@ -134,7 +134,7 @@ func (c *Client) Close() error {
 
 // connect dials the WebSocket endpoint and waits for the welcome message.
 func (c *Client) connect(ctx context.Context) error {
-	url := c.wsURL + "?x_cg_pro_api_key=" + c.cfg.APIKey
+	url := c.wsURL + "?x_cg_pro_api_key=" + c.cfg.APIKey + "&source=cli"
 
 	header := http.Header{}
 	header.Set("User-Agent", c.UserAgent)

internal/ws/client_test.go

@@ -379,6 +379,42 @@ func TestConnect_APIKeyInQueryParam(t *testing.T) {
 	require.NoError(t, client.Close())
 }
 
+func TestConnect_SourceCLIQueryParam(t *testing.T) {
+	var receivedSource string
+	var mu sync.Mutex
+
+	srv := newTestWSServer(t, func(conn *websocket.Conn) {
+		happyHandshake(t, conn)
+		for {
+			if _, _, err := conn.ReadMessage(); err != nil {
+				return
+			}
+		}
+	})
+	origHandler := srv.Config.Handler
+	srv.Config.Handler = http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		mu.Lock()
+		receivedSource = r.URL.Query().Get("source")
+		mu.Unlock()
+		origHandler.ServeHTTP(w, r)
+	})
+
+	client := NewClient(paidCfg(), []string{"bitcoin"})
+	client.SetURL(wsURL(srv))
+
+	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+	defer cancel()
+
+	_, err := client.Connect(ctx)
+	require.NoError(t, err)
+
+	mu.Lock()
+	assert.Equal(t, "cli", receivedSource)
+	mu.Unlock()
+
+	require.NoError(t, client.Close())
+}
+
 func TestConnect_UserAgentHeader(t *testing.T) {
 	var gotUA string
 	var mu sync.Mutex