Enable reactive reference highlighting by default (#7483)

This is now a mature feature, so we're changing the default from off to
on.

Author: manzt

frontend/src/core/codemirror/cm.ts

@@ -152,7 +152,7 @@ export const setupCodeMirror = (opts: CodeMirrorSetupOpts): Extension[] => {
     // Reactive references highlighting
     reactiveReferencesBundle(
       cellId,
-      displayConfig.reference_highlighting ?? false,
+      displayConfig.reference_highlighting ?? true,
     ),
   ];
 };

frontend/src/core/config/__tests__/config-schema.test.ts

@@ -65,7 +65,7 @@ test("default UserConfig - empty", () => {
         "default_table_max_columns": 50,
         "default_table_page_size": 10,
         "default_width": "medium",
-        "reference_highlighting": false,
+        "reference_highlighting": true,
         "theme": "light",
       },
       "experimental": {},
@@ -133,7 +133,7 @@ test("default UserConfig - one level", () => {
         "default_table_max_columns": 50,
         "default_table_page_size": 10,
         "default_width": "medium",
-        "reference_highlighting": false,
+        "reference_highlighting": true,
         "theme": "light",
       },
       "experimental": {},

frontend/src/core/config/config-schema.ts

@@ -145,7 +145,7 @@ export const UserConfigSchema = z
             return width;
           }),
         locale: z.string().nullable().optional(),
-        reference_highlighting: z.boolean().prefault(false),
+        reference_highlighting: z.boolean().prefault(true),
       })
       .prefault({}),
     package_management: z

marimo/_config/config.py

@@ -632,7 +632,7 @@ class PartialMarimoConfig(TypedDict, total=False):
         "dataframes": "rich",
         "default_table_page_size": 10,
         "default_table_max_columns": 50,
-        "reference_highlighting": False,
+        "reference_highlighting": True,
     },
     "formatting": {"line_length": 79},
     "keymap": {"preset": "default", "overrides": {}},