diff --git a/cmd/server/routes.go b/cmd/server/routes.go
index 6570ccf..7fd8133 100644
--- a/cmd/server/routes.go
+++ b/cmd/server/routes.go
@@ -293,7 +293,12 @@ func (s *Server) handleConfigTheme(w http.ResponseWriter, r *http.Request) {
 	}, s.cfg.NodeColors, theme.NodeColors)
 
 	themeDark := mergeMap(map[string]interface{}{}, s.cfg.ThemeDark, theme.ThemeDark)
-	typeColors := mergeMap(map[string]interface{}{}, s.cfg.TypeColors, theme.TypeColors)
+	typeColors := mergeMap(map[string]interface{}{
+		"ADVERT": "#22c55e", "GRP_TXT": "#3b82f6", "TXT_MSG": "#f59e0b",
+		"ACK": "#6b7280", "REQUEST": "#a855f7", "RESPONSE": "#06b6d4",
+		"TRACE": "#ec4899", "PATH": "#14b8a6", "ANON_REQ": "#f43f5e",
+		"UNKNOWN": "#6b7280",
+	}, s.cfg.TypeColors, theme.TypeColors)
 
 	var home interface{}
 	if theme.Home != nil {
diff --git a/cmd/server/routes_test.go b/cmd/server/routes_test.go
index a06201c..c6fa338 100644
--- a/cmd/server/routes_test.go
+++ b/cmd/server/routes_test.go
@@ -454,6 +454,35 @@ func TestConfigThemeEndpoint(t *testing.T) {
 	}
 }
 
+func TestConfigThemeTypeColorsDefaults(t *testing.T) {
+	_, router := setupTestServer(t)
+	req := httptest.NewRequest("GET", "/api/config/theme", nil)
+	w := httptest.NewRecorder()
+	router.ServeHTTP(w, req)
+
+	if w.Code != 200 {
+		t.Fatalf("expected 200, got %d", w.Code)
+	}
+	var body map[string]interface{}
+	json.Unmarshal(w.Body.Bytes(), &body)
+	tc, ok := body["typeColors"].(map[string]interface{})
+	if !ok {
+		t.Fatal("expected typeColors object in theme response")
+	}
+	expectedTypes := []string{"ADVERT", "GRP_TXT", "TXT_MSG", "ACK", "REQUEST", "RESPONSE", "TRACE", "PATH", "ANON_REQ", "UNKNOWN"}
+	for _, typ := range expectedTypes {
+		val, exists := tc[typ]
+		if !exists {
+			t.Errorf("typeColors missing default for %s", typ)
+			continue
+		}
+		color, ok := val.(string)
+		if !ok || color == "" || color == "#000000" {
+			t.Errorf("typeColors[%s] should be a non-black color, got %v", typ, val)
+		}
+	}
+}
+
 func TestConfigMapEndpoint(t *testing.T) {
 	_, router := setupTestServer(t)
 	req := httptest.NewRequest("GET", "/api/config/map", nil)
diff --git a/public/customize-v2.js b/public/customize-v2.js
index 577f6be..0c9a795 100644
--- a/public/customize-v2.js
+++ b/public/customize-v2.js
@@ -966,7 +966,7 @@
     var stc = server.typeColors || {};
     var typeRows = '';
     for (var tkey in TYPE_LABELS) {
-      var tval = tc[tkey] || '#000000';
+      var tval = tc[tkey] || (window.TYPE_COLORS && window.TYPE_COLORS[tkey]) || '#000000';
       typeRows += '<div class="cust-color-row">' +
         '<div><label>' + (TYPE_EMOJI[tkey] || '') + ' ' + TYPE_LABELS[tkey] + _overrideDot('typeColors', tkey) + '</label>' +
         '<div class="cust-hint">' + (TYPE_HINTS[tkey] || '') + '</div></div>' +
diff --git a/test-frontend-helpers.js b/test-frontend-helpers.js
index 9508b4f..6c784cc 100644
--- a/test-frontend-helpers.js
+++ b/test-frontend-helpers.js
@@ -2020,6 +2020,24 @@ console.log('\n=== customize-v2.js: core behavior ===');
     assert.ok(src.includes("surface3: '--surface-3'"), 'surface3 must map to --surface-3');
     assert.ok(src.includes("sectionBg: '--section-bg'"), 'sectionBg must map to --section-bg');
   });
+
+  test('_renderNodes falls back to window.TYPE_COLORS when typeColors is empty (#514)', () => {
+    const ctx = makeSandbox();
+    ctx.CustomEvent = function (type) { this.type = type; };
+    ctx.TYPE_COLORS = { ADVERT: '#22c55e', GRP_TXT: '#3b82f6' };
+    ctx.window.TYPE_COLORS = ctx.TYPE_COLORS;
+    const v2 = loadCustomizeV2(ctx);
+    // computeEffective with empty typeColors should still allow fallback
+    const server = { typeColors: {} };
+    const effective = v2.computeEffective(server, {});
+    // When typeColors is empty, the render should fall back to TYPE_COLORS
+    // We test the logic directly: tc[key] || TYPE_COLORS[key] || '#000000'
+    const tc = effective.typeColors || {};
+    const advertColor = tc['ADVERT'] || (ctx.window.TYPE_COLORS && ctx.window.TYPE_COLORS['ADVERT']) || '#000000';
+    assert.strictEqual(advertColor, '#22c55e', 'ADVERT should fall back to TYPE_COLORS, not #000000');
+    const grpColor = tc['GRP_TXT'] || (ctx.window.TYPE_COLORS && ctx.window.TYPE_COLORS['GRP_TXT']) || '#000000';
+    assert.strictEqual(grpColor, '#3b82f6', 'GRP_TXT should fall back to TYPE_COLORS, not #000000');
+  });
 }
 
 // ===== APP.JS: home rehydration merge (mergeUserHomeConfig removed — dead code) =====