refactor(extensions): use declare function pattern for colors bridge

Replace the registry-with-state implementation in @apache-superset/core/colors
with declare-only function signatures. The host app (ExtensionsStartup) now
provides the concrete implementations via window.superset.colors, matching
the same pattern used by the authentication module.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

superset-frontend/packages/superset-core/package.json

@@ -58,6 +58,10 @@
       "types": "./lib/components/index.d.ts",
       "default": "./lib/components/index.js"
     },
+    "./colors": {
+      "types": "./lib/colors/index.d.ts",
+      "default": "./lib/colors/index.js"
+    },
     "./utils": {
       "types": "./lib/utils/index.d.ts",
       "default": "./lib/utils/index.js"

superset-frontend/packages/superset-core/src/colors/colors.test.ts

@@ -0,0 +1,28 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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.
+ */
+
+import { ColorSchemeGroup } from '@apache-superset/core/colors';
+
+// ─── ColorSchemeGroup enum ────────────────────────────────────────────────────
+
+test('ColorSchemeGroup has the expected string values', () => {
+  expect(ColorSchemeGroup.Custom).toBe('custom');
+  expect(ColorSchemeGroup.Featured).toBe('featured');
+  expect(ColorSchemeGroup.Other).toBe('other');
+});

superset-frontend/packages/superset-core/src/colors/index.ts

@@ -0,0 +1,51 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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.
+ */
+
+// Types & enums for color scheme configuration — usable by extensions and host alike
+export type { ColorSchemeConfig, SequentialSchemeConfig } from './types';
+export { ColorSchemeGroup } from './types';
+
+/**
+ * Minimal interface for the categorical color scheme registry.
+ * Mirrors the public surface of @superset-ui/core's ColorSchemeRegistry.
+ */
+export interface CategoricalScheme {
+  id: string;
+  label?: string;
+  colors: string[];
+}
+
+export interface CategoricalSchemeRegistryLike {
+  keys(): string[];
+  get(name: string): CategoricalScheme | null | undefined;
+}
+
+/**
+ * Returns an alphabetically sorted list of all registered categorical color
+ * scheme names. The host app (ExtensionsStartup) provides the implementation
+ * via window.superset.colors.
+ */
+export declare function getCategoricalSchemeNames(): string[];
+
+/**
+ * Returns the color array for a named scheme, or null if not found.
+ * The host app (ExtensionsStartup) provides the implementation
+ * via window.superset.colors.
+ */
+export declare function getSchemeColors(schemeName: string): string[] | null;

superset-frontend/packages/superset-core/src/colors/types.ts

@@ -0,0 +1,46 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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.
+ */
+
+/**
+ * Grouping/tier for a color scheme — controls how it appears in the
+ * scheme picker UI (e.g. Featured palettes are shown first).
+ *
+ * Mirrors @superset-ui/core's ColorSchemeGroup; kept here so
+ * palette configs have no dependency on @superset-ui/core.
+ */
+export enum ColorSchemeGroup {
+  Custom = 'custom',
+  Featured = 'featured',
+  Other = 'other',
+}
+
+/** Plain configuration object for a categorical color scheme. */
+export interface ColorSchemeConfig {
+  id: string;
+  label?: string;
+  colors: string[];
+  description?: string;
+  isDefault?: boolean;
+  group?: ColorSchemeGroup;
+}
+
+/** Extension of ColorSchemeConfig for sequential / diverging schemes. */
+export interface SequentialSchemeConfig extends ColorSchemeConfig {
+  isDiverging?: boolean;
+}

superset-frontend/packages/superset-core/src/index.ts

@@ -29,3 +29,4 @@ export * as theme from './theme';
 export * as translation from './translation';
 export * as components from './components';
 export * as utils from './utils';
+export * as colors from './colors';

superset-frontend/packages/superset-ui-core/test/color/colorSchemes.test.ts

@@ -24,6 +24,12 @@ import {
   CategoricalD3,
   CategoricalGoogle,
   CategoricalLyft,
+  CategoricalModernSunset,
+  CategoricalColorsOfRainbow,
+  CategoricalBlueToGreen,
+  CategoricalRedToYellow,
+  CategoricalWavesOfBlue,
+  CategoricalPresetSuperset,
   SequentialCommon,
   SequentialD3,
   CategoricalScheme,
@@ -41,22 +47,59 @@ describe('Color Schemes', () => {
         CategoricalLyft,
         CategoricalSuperset,
         CategoricalPreset,
+        CategoricalModernSunset,
+        CategoricalColorsOfRainbow,
+        CategoricalBlueToGreen,
+        CategoricalRedToYellow,
+        CategoricalWavesOfBlue,
+        CategoricalPresetSuperset,
       ].forEach(group => {
         expect(group).toBeInstanceOf(Array);
+        expect(group.length).toBeGreaterThan(0);
         group.forEach(scheme =>
           expect(scheme).toBeInstanceOf(CategoricalScheme),
         );
       });
     });
+
+    test('each scheme has a non-empty id and at least one color', () => {
+      [
+        ...CategoricalAirbnb,
+        ...CategoricalD3,
+        ...CategoricalEcharts,
+        ...CategoricalGoogle,
+        ...CategoricalLyft,
+        ...CategoricalPreset,
+        ...CategoricalSuperset,
+        ...CategoricalPresetSuperset,
+        ...CategoricalModernSunset,
+        ...CategoricalColorsOfRainbow,
+        ...CategoricalBlueToGreen,
+        ...CategoricalRedToYellow,
+        ...CategoricalWavesOfBlue,
+      ].forEach(scheme => {
+        expect(scheme.id).toBeTruthy();
+        expect(scheme.colors.length).toBeGreaterThan(0);
+      });
+    });
   });
+
   describe('sequential', () => {
     test('returns an array of SequentialScheme', () => {
       [SequentialCommon, SequentialD3].forEach(group => {
         expect(group).toBeInstanceOf(Array);
+        expect(group.length).toBeGreaterThan(0);
         group.forEach(scheme =>
           expect(scheme).toBeInstanceOf(SequentialScheme),
         );
       });
     });
+
+    test('each scheme has a non-empty id and at least two colors', () => {
+      [...SequentialCommon, ...SequentialD3].forEach(scheme => {
+        expect(scheme.id).toBeTruthy();
+        expect(scheme.colors.length).toBeGreaterThanOrEqual(2);
+      });
+    });
   });
 });

superset-frontend/scripts/check-custom-rules.js

@@ -593,7 +593,7 @@ function main() {
     /\.stories\./,
     /\/demo\//,
     /\/examples\//,
-    /\/color\/colorSchemes\//,
+    /\/color\/colorSchemes\//, // @superset-ui/core palette scheme definitions legitimately contain colors
     /\/cypress\//,
     /\/cypress-base\//,
     /\/esm\//,

superset-frontend/src/extensions/ExtensionsStartup.tsx

@@ -19,7 +19,12 @@
 import { useEffect, useState } from 'react';
 // eslint-disable-next-line no-restricted-syntax
 import * as supersetCore from '@apache-superset/core';
-import { FeatureFlag, isFeatureEnabled } from '@superset-ui/core';
+import {
+  FeatureFlag,
+  isFeatureEnabled,
+  getCategoricalSchemeRegistry,
+} from '@superset-ui/core';
+import type { CategoricalSchemeRegistryLike } from '@apache-superset/core/colors';
 import {
   authentication,
   core,
@@ -45,6 +50,11 @@ declare global {
       menus: typeof menus;
       sqlLab: typeof sqlLab;
       views: typeof views;
+      colors: {
+        ColorSchemeGroup: typeof supersetCore.colors.ColorSchemeGroup;
+        getCategoricalSchemeNames(): string[];
+        getSchemeColors(schemeName: string): string[] | null;
+      };
     };
   }
 }
@@ -68,6 +78,8 @@ const ExtensionsStartup: React.FC<{ children?: React.ReactNode }> = ({
     }
 
     // Provide the implementations for @apache-superset/core
+    const registry =
+      getCategoricalSchemeRegistry() as CategoricalSchemeRegistryLike | null;
     window.superset = {
       ...supersetCore,
       authentication,
@@ -78,6 +90,15 @@ const ExtensionsStartup: React.FC<{ children?: React.ReactNode }> = ({
       menus,
       sqlLab,
       views,
+      colors: {
+        ColorSchemeGroup: supersetCore.colors.ColorSchemeGroup,
+        getCategoricalSchemeNames(): string[] {
+          return (registry?.keys() ?? []).sort();
+        },
+        getSchemeColors(schemeName: string): string[] | null {
+          return registry?.get(schemeName)?.colors ?? null;
+        },
+      },
     };
 
     const setup = async () => {