Merge branch 'master' into enxdev/chat-prototype

Co-authored-by: Evan Rusackas <evan@preset.io>
Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

superset-frontend/package-lock.json

@@ -8450,9 +8450,6 @@
         "arm64"
       ],
       "dev": true,
-      "libc": [
-        "glibc"
-      ],
       "license": "MIT",
       "optional": true,
       "os": [
@@ -8470,9 +8467,6 @@
         "arm64"
       ],
       "dev": true,
-      "libc": [
-        "musl"
-      ],
       "license": "MIT",
       "optional": true,
       "os": [
@@ -8490,9 +8484,6 @@
         "ppc64"
       ],
       "dev": true,
-      "libc": [
-        "glibc"
-      ],
       "license": "MIT",
       "optional": true,
       "os": [
@@ -8510,9 +8501,6 @@
         "riscv64"
       ],
       "dev": true,
-      "libc": [
-        "glibc"
-      ],
       "license": "MIT",
       "optional": true,
       "os": [
@@ -8530,9 +8518,6 @@
         "riscv64"
       ],
       "dev": true,
-      "libc": [
-        "musl"
-      ],
       "license": "MIT",
       "optional": true,
       "os": [
@@ -8550,9 +8535,6 @@
         "s390x"
       ],
       "dev": true,
-      "libc": [
-        "glibc"
-      ],
       "license": "MIT",
       "optional": true,
       "os": [
@@ -8570,9 +8552,6 @@
         "x64"
       ],
       "dev": true,
-      "libc": [
-        "glibc"
-      ],
       "license": "MIT",
       "optional": true,
       "os": [
@@ -8590,9 +8569,6 @@
         "x64"
       ],
       "dev": true,
-      "libc": [
-        "musl"
-      ],
       "license": "MIT",
       "optional": true,
       "os": [
@@ -26132,6 +26108,21 @@
         }
       }
     },
+    "node_modules/jsdom/node_modules/@noble/hashes": {
+      "version": "2.2.0",
+      "resolved": "https://registry.npmjs.org/@noble/hashes/-/hashes-2.2.0.tgz",
+      "integrity": "sha512-IYqDGiTXab6FniAgnSdZwgWbomxpy9FtYvLKs7wCUs2a8RkITG+DFGO1DM9cr+E3/RgADRpFjrKVaJ1z6sjtEg==",
+      "dev": true,
+      "license": "MIT",
+      "optional": true,
+      "peer": true,
+      "engines": {
+        "node": ">= 20.19.0"
+      },
+      "funding": {
+        "url": "https://paulmillr.com/funding/"
+      }
+    },
     "node_modules/jsdom/node_modules/css-tree": {
       "version": "3.2.1",
       "resolved": "https://registry.npmjs.org/css-tree/-/css-tree-3.2.1.tgz",
@@ -43244,6 +43235,21 @@
         }
       }
     },
+    "node_modules/whatwg-url/node_modules/@noble/hashes": {
+      "version": "2.2.0",
+      "resolved": "https://registry.npmjs.org/@noble/hashes/-/hashes-2.2.0.tgz",
+      "integrity": "sha512-IYqDGiTXab6FniAgnSdZwgWbomxpy9FtYvLKs7wCUs2a8RkITG+DFGO1DM9cr+E3/RgADRpFjrKVaJ1z6sjtEg==",
+      "dev": true,
+      "license": "MIT",
+      "optional": true,
+      "peer": true,
+      "engines": {
+        "node": ">= 20.19.0"
+      },
+      "funding": {
+        "url": "https://paulmillr.com/funding/"
+      }
+    },
     "node_modules/whatwg-url/node_modules/webidl-conversions": {
       "version": "8.0.1",
       "resolved": "https://registry.npmjs.org/webidl-conversions/-/webidl-conversions-8.0.1.tgz",

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

@@ -18,6 +18,14 @@
       "types": "./lib/authentication/index.d.ts",
       "default": "./lib/authentication/index.js"
     },
+    "./chat": {
+      "types": "./lib/chat/index.d.ts",
+      "default": "./lib/chat/index.js"
+    },
+    "./navigation": {
+      "types": "./lib/navigation/index.d.ts",
+      "default": "./lib/navigation/index.js"
+    },
     "./commands": {
       "types": "./lib/commands/index.d.ts",
       "default": "./lib/commands/index.js"

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

@@ -0,0 +1,184 @@
+/**
+ * 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.
+ */
+
+/**
+ * @fileoverview Chat contribution API for Superset extensions.
+ *
+ * Chat is a dedicated contribution type (not a view): an extension registers
+ * a chat via {@link registerChat} and the host owns where and how it is
+ * mounted. The host applies singleton resolution — multiple chat extensions
+ * may register, but exactly one is active at a time.
+ *
+ * @example
+ * ```typescript
+ * import { chat } from '@apache-superset/core';
+ *
+ * chat.registerChat(
+ *   { id: 'acme.chat', name: 'Acme Chat' },
+ *   () => <AcmeTrigger />,
+ *   () => <AcmePanel />,
+ * );
+ * ```
+ */
+
+import { ReactElement } from 'react';
+import type { Disposable, Event } from '../common';
+
+export interface Chat {
+  /** The unique identifier for the chat. */
+  id: string;
+  /** The display name of the chat. */
+  name: string;
+  /** Optional description of the chat, for display in contribution manifests. */
+  description?: string;
+}
+
+export type DisplayMode = 'floating' | 'panel';
+
+/**
+ * Registers a chat provider. The host applies singleton resolution — only one
+ * chat is active at a time: the most recently registered chat wins, and
+ * disposing it restores the previously registered one. Re-registering an id
+ * replaces that registration in place.
+ *
+ * When a registration with a different id takes over the active slot (or the
+ * active chat is disposed), the host closes the panel first, firing
+ * {@link onDidClose}; an in-place same-id replacement keeps the open state.
+ *
+ * Disposing the returned Disposable unregisters the chat.
+ *
+ * @param chat The chat descriptor (id, name).
+ * @param trigger A function returning the collapsed bubble element. Owned by
+ *   the extension — dynamic state such as unread counts and badges lives here.
+ *   Hidden by the host when in panel mode.
+ * @param panel A function returning the chat panel element. Mounted by the
+ *   host as a floating overlay in 'floating' mode, or docked at the side of
+ *   the viewport in 'panel' mode (the reference host docks a fixed-width
+ *   overlay at the right edge; hosts may integrate a true layout slot
+ *   instead). Same component in both modes.
+ * @returns A Disposable that unregisters the chat when disposed.
+ *
+ * @example
+ * ```typescript
+ * chat.registerChat(
+ *   { id: 'acme.chat', name: 'Acme Chat' },
+ *   () => <AcmeTrigger />,
+ *   () => <AcmePanel />,
+ * );
+ * ```
+ */
+export declare function registerChat(
+  chat: Chat,
+  trigger: () => ReactElement,
+  panel: () => ReactElement,
+): Disposable;
+
+/**
+ * Returns the active chat descriptor.
+ *
+ * @returns A copy of the active Chat descriptor, or undefined if none is
+ *   registered. Mutating the returned object has no effect on the registry.
+ */
+export declare function getChat(): Chat | undefined;
+
+/**
+ * Event fired when a chat is registered.
+ */
+export declare const onDidRegisterChat: Event<Chat>;
+
+/**
+ * Event fired when a chat is unregistered.
+ */
+export declare const onDidUnregisterChat: Event<Chat>;
+
+/**
+ * Opens the active chat's panel.
+ *
+ * Acts on whichever chat is active, regardless of which extension calls it.
+ * No-op when no chat is registered or the panel is already open.
+ */
+export declare function open(): void;
+
+/**
+ * Closes the active chat's panel.
+ *
+ * Acts on whichever chat is active, regardless of which extension calls it.
+ * No-op when the panel is not open.
+ */
+export declare function close(): void;
+
+/**
+ * Returns whether the active chat's panel is currently open.
+ *
+ * @returns True if the chat panel is open.
+ */
+export declare function isOpen(): boolean;
+
+/**
+ * Event fired when the chat panel opens. Also fired by the host's own
+ * controls, not only by an extension's open() call.
+ */
+export declare const onDidOpen: Event<void>;
+
+/**
+ * Event fired when the chat panel closes. Also fired when the host closes the
+ * panel itself, e.g. because the active chat was disposed or displaced by a
+ * different chat.
+ */
+export declare const onDidClose: Event<void>;
+
+/**
+ * Returns the current display mode.
+ *
+ * @returns The current DisplayMode.
+ */
+export declare function getDisplayMode(): DisplayMode;
+
+/**
+ * Sets the display mode.
+ *
+ * The mode is host-global and applies to whichever chat is active, regardless
+ * of which extension calls it. Hosts may also change the mode through their
+ * own controls — use onDidChangeDisplayMode to observe all changes rather than
+ * assuming the last setDisplayMode() call won.
+ *
+ * @param displayMode The display mode to switch to.
+ */
+export declare function setDisplayMode(displayMode: DisplayMode): void;
+
+/**
+ * Event fired when the display mode changes, whether triggered by an
+ * extension via setDisplayMode() or by host-provided controls.
+ */
+export declare const onDidChangeDisplayMode: Event<DisplayMode>;
+
+/**
+ * Event fired when the panel is resized in panel mode.
+ *
+ * The host owns the resizer handle and drag interaction; a host without a
+ * resizer never fires this event. (The reference host mounts the panel at a
+ * fixed width and does not provide a resizer, so subscribers receive no
+ * events there.) Listen to this event to adapt internal layout to the
+ * available width; do not rely on it firing.
+ */
+export declare const onDidResizePanel: Event<{ width: number }>;
+
+// TODO: client actions API — tool availability functions will be added here
+// once the client_actions SIP is finalized. The chat namespace is the
+// intended integration point between the two SIPs.

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

@@ -223,8 +223,6 @@ export interface Extension {
   dependencies: string[];
   /** Human-readable description of the extension */
   description: string;
-  /** List of other extensions that this extension depends on */
-  extensionDependencies: string[];
   /** Unique identifier for the extension */
   id: string;
   /** Human-readable name of the extension */

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

@@ -23,9 +23,10 @@
  * This module defines the aggregate interfaces used by the extension.json
  * manifest and the `superset-extensions` build command. Individual metadata
  * types are defined in their respective namespace modules (commands, views,
- * menus, editors) and re-exported here for the manifest schema.
+ * menus, editors, chat) and re-exported here for the manifest schema.
  */
 
+import { Chat } from '../chat';
 import { Command } from '../commands';
 import { View } from '../views';
 import { Menu } from '../menus';
@@ -71,7 +72,8 @@ export interface MenuContributions {
 }
 
 /**
- * Aggregates all contributions (commands, menus, views, and editors) provided by an extension or module.
+ * Aggregates all contributions (commands, menus, views, editors, and chat)
+ * provided by an extension or module.
  */
 export interface Contributions {
   /** List of commands. */
@@ -82,4 +84,10 @@ export interface Contributions {
   views: ViewContributions;
   /** List of editors. */
   editors?: Editor[];
+  /**
+   * The chat contributed by the extension — at most one per extension, since
+   * the host applies singleton resolution and renders exactly one active
+   * chat at a time.
+   */
+  chat?: Chat;
 }

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

@@ -18,10 +18,12 @@
  */
 export * as common from './common';
 export * as authentication from './authentication';
+export * as chat from './chat';
 export * as commands from './commands';
 export * as editors from './editors';
 export * as extensions from './extensions';
 export * as menus from './menus';
+export * as navigation from './navigation';
 export * as sqlLab from './sqlLab';
 export * as views from './views';
 export * as contributions from './contributions';

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

@@ -0,0 +1,81 @@
+/**
+ * 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.
+ */
+
+/**
+ * @fileoverview Navigation namespace for Superset extensions.
+ *
+ * Exposes the current application surface so extensions can react to route
+ * changes without polling. Entity-level context (chart, dashboard, dataset)
+ * is intentionally not included here — surface-specific namespaces that
+ * resolve entity payloads are introduced in later phases.
+ */
+
+import { Event } from '../common';
+
+/**
+ * The set of top-level application surfaces.
+ *
+ * `'explore'`, `'dashboard'` and `'dataset'` are the single-entity
+ * editing/viewing surfaces. `'chart_list'`, `'dashboard_list'` and
+ * `'dataset_list'` are the browse/list surfaces, distinct from those because no
+ * single entity is active. `'sqllab'` is the SQL editor where
+ * `sqlLab.getCurrentTab()` resolves; `'query_history'` and `'saved_queries'`
+ * are the related SQL Lab browse pages, which are not the editor. `'home'` is
+ * the welcome surface and the fallback for any route not explicitly enumerated.
+ */
+export type Page =
+  | 'dashboard'
+  | 'dashboard_list'
+  | 'explore'
+  | 'chart_list'
+  | 'sqllab'
+  | 'query_history'
+  | 'saved_queries'
+  | 'dataset'
+  | 'dataset_list'
+  | 'home';
+
+/**
+ * Returns the current page surface.
+ *
+ * @example
+ * ```typescript
+ * const page = navigation.getPage();
+ * if (page === 'dashboard') {
+ *   // react to being on a dashboard surface
+ * }
+ * ```
+ */
+export declare function getPage(): Page;
+
+/**
+ * Event fired whenever the user navigates to a different surface.
+ *
+ * @example
+ * ```typescript
+ * const sub = navigation.onDidChangePage(page => {
+ *   if (page === 'dashboard') {
+ *     // react to navigating onto a dashboard surface
+ *   }
+ * });
+ * // later:
+ * sub.dispose();
+ * ```
+ */
+export declare const onDidChangePage: Event<Page>;

superset-frontend/src/components/ChatMount/ChatMount.test.tsx

@@ -0,0 +1,287 @@
+/**
+ * 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 { act, render, screen } from 'spec/helpers/testing-library';
+import { chat } from 'src/core/chat';
+import ChatMount from '.';
+
+const disposables: Array<{ dispose: () => void }> = [];
+
+afterEach(() => {
+  act(() => {
+    disposables.forEach(d => d.dispose());
+    disposables.length = 0;
+    // Reset host-owned state shared across tests in this module.
+    chat.close();
+    chat.setDisplayMode('floating');
+  });
+});
+
+test('renders nothing when no chat extension is registered', () => {
+  render(<ChatMount />);
+
+  expect(screen.queryByTestId('chat-mount')).not.toBeInTheDocument();
+});
+
+test('renders the trigger bubble of the registered chat', () => {
+  disposables.push(
+    chat.registerChat(
+      { id: 'acme.chat', name: 'Acme Chat' },
+      () => <button type="button">Acme Bubble</button>,
+      () => <div>Acme Panel</div>,
+    ),
+  );
+
+  render(<ChatMount />);
+
+  expect(screen.getByTestId('chat-mount')).toBeInTheDocument();
+  expect(screen.getByText('Acme Bubble')).toBeInTheDocument();
+  // The panel stays unmounted until the chat is opened.
+  expect(screen.queryByText('Acme Panel')).not.toBeInTheDocument();
+});
+
+test('mounts the panel when the chat opens and unmounts it on close', () => {
+  disposables.push(
+    chat.registerChat(
+      { id: 'acme.chat', name: 'Acme Chat' },
+      () => <button type="button">Acme Bubble</button>,
+      () => <div>Acme Panel</div>,
+    ),
+  );
+
+  render(<ChatMount />);
+
+  act(() => chat.open());
+
+  expect(screen.getByText('Acme Panel')).toBeInTheDocument();
+  // In floating mode the trigger stays mounted alongside the open panel.
+  expect(screen.getByText('Acme Bubble')).toBeInTheDocument();
+
+  act(() => chat.close());
+
+  expect(screen.queryByText('Acme Panel')).not.toBeInTheDocument();
+});
+
+test('renders the last-registered chat when several are installed', () => {
+  disposables.push(
+    chat.registerChat(
+      { id: 'first.chat', name: 'First Chat' },
+      () => <div>First Bubble</div>,
+      () => <div>First Panel</div>,
+    ),
+    chat.registerChat(
+      { id: 'second.chat', name: 'Second Chat' },
+      () => <div>Second Bubble</div>,
+      () => <div>Second Panel</div>,
+    ),
+  );
+
+  render(<ChatMount />);
+
+  // Last-loaded wins: the second registration takes over the singleton slot.
+  expect(screen.getByText('Second Bubble')).toBeInTheDocument();
+  expect(screen.queryByText('First Bubble')).not.toBeInTheDocument();
+});
+
+test('reacts to a chat registering after the initial render', () => {
+  render(<ChatMount />);
+
+  expect(screen.queryByTestId('chat-mount')).not.toBeInTheDocument();
+
+  act(() => {
+    disposables.push(
+      chat.registerChat(
+        { id: 'acme.chat', name: 'Acme Chat' },
+        () => <button type="button">Acme Bubble</button>,
+        () => <div>Acme Panel</div>,
+      ),
+    );
+  });
+
+  expect(screen.getByText('Acme Bubble')).toBeInTheDocument();
+});
+
+test('a takeover mounts the incoming chat closed', () => {
+  disposables.push(
+    chat.registerChat(
+      { id: 'first.chat', name: 'First Chat' },
+      () => <div>First Bubble</div>,
+      () => <div>First Panel</div>,
+    ),
+  );
+
+  render(<ChatMount />);
+  act(() => chat.open());
+  expect(screen.getByText('First Panel')).toBeInTheDocument();
+
+  act(() => {
+    disposables.push(
+      chat.registerChat(
+        { id: 'second.chat', name: 'Second Chat' },
+        () => <div>Second Bubble</div>,
+        () => <div>Second Panel</div>,
+      ),
+    );
+  });
+
+  // The displaced chat's open state must not leak into the winner.
+  expect(screen.getByText('Second Bubble')).toBeInTheDocument();
+  expect(screen.queryByText('Second Panel')).not.toBeInTheDocument();
+  expect(screen.queryByText('First Panel')).not.toBeInTheDocument();
+});
+
+test('panel mode docks the open panel and hides the trigger', () => {
+  disposables.push(
+    chat.registerChat(
+      { id: 'acme.chat', name: 'Acme Chat' },
+      () => <button type="button">Acme Bubble</button>,
+      () => <div>Acme Panel</div>,
+    ),
+  );
+
+  render(<ChatMount />);
+
+  act(() => {
+    chat.setDisplayMode('panel');
+    chat.open();
+  });
+
+  expect(screen.getByText('Acme Panel')).toBeInTheDocument();
+  expect(screen.queryByText('Acme Bubble')).not.toBeInTheDocument();
+
+  act(() => chat.close());
+
+  // A closed chat in panel mode renders nothing — the trigger is hidden too.
+  expect(screen.queryByTestId('chat-mount')).not.toBeInTheDocument();
+});
+
+test('a crashing panel does not take the trigger down with it', () => {
+  const FailingPanel = () => {
+    throw new Error('panel blew up');
+  };
+  disposables.push(
+    chat.registerChat(
+      { id: 'acme.chat', name: 'Acme Chat' },
+      () => <button type="button">Acme Bubble</button>,
+      () => <FailingPanel />,
+    ),
+  );
+
+  render(<ChatMount />);
+  act(() => chat.open());
+
+  // The panel's boundary contains the crash; the trigger keeps rendering so
+  // the user is not stranded without a way back.
+  expect(screen.queryByText('panel blew up')).not.toBeInTheDocument();
+  expect(screen.getByText('Acme Bubble')).toBeInTheDocument();
+});
+
+test('isolates a failing trigger so it does not crash the host', () => {
+  const FailingTrigger = () => {
+    throw new Error('chat blew up');
+  };
+  disposables.push(
+    chat.registerChat(
+      { id: 'acme.chat', name: 'Acme Chat' },
+      () => <FailingTrigger />,
+      () => <div>Acme Panel</div>,
+    ),
+  );
+
+  // The host-owned error boundary catches the failure; render does not throw.
+  expect(() => render(<ChatMount />)).not.toThrow();
+  // The mount slot still renders (the boundary lives inside it), confirming
+  // the provider was actually exercised and contained.
+  expect(screen.getByTestId('chat-mount')).toBeInTheDocument();
+});
+
+test('isolates a chat whose provider function itself throws', () => {
+  disposables.push(
+    chat.registerChat(
+      { id: 'acme.chat', name: 'Acme Chat' },
+      () => {
+        throw new Error('provider blew up');
+      },
+      () => <div>Acme Panel</div>,
+    ),
+  );
+
+  // ChatRenderer wraps provider() in a component so ErrorBoundary catches
+  // synchronous throws from the provider function, not just from its output.
+  expect(() => render(<ChatMount />)).not.toThrow();
+  expect(screen.getByTestId('chat-mount')).toBeInTheDocument();
+});
+
+test('recovers from a crashed chat when a different chat takes over', () => {
+  const FailingTrigger = () => {
+    throw new Error('first chat blew up');
+  };
+  disposables.push(
+    chat.registerChat(
+      { id: 'first.chat', name: 'First Chat' },
+      () => <FailingTrigger />,
+      () => <div>First Panel</div>,
+    ),
+  );
+
+  render(<ChatMount />);
+  expect(screen.queryByText('Second Bubble')).not.toBeInTheDocument();
+
+  act(() => {
+    disposables.push(
+      chat.registerChat(
+        { id: 'second.chat', name: 'Second Chat' },
+        () => <div>Second Bubble</div>,
+        () => <div>Second Panel</div>,
+      ),
+    );
+  });
+
+  // The boundary is keyed per registration, so the latched crash from the
+  // first chat does not blank the second one.
+  expect(screen.getByText('Second Bubble')).toBeInTheDocument();
+});
+
+test('recovers when a crashed chat re-registers a fixed version under the same id', () => {
+  const FailingTrigger = () => {
+    throw new Error('broken release');
+  };
+  disposables.push(
+    chat.registerChat(
+      { id: 'acme.chat', name: 'Acme Chat' },
+      () => <FailingTrigger />,
+      () => <div>Acme Panel</div>,
+    ),
+  );
+
+  render(<ChatMount />);
+  expect(screen.queryByText('Fixed Bubble')).not.toBeInTheDocument();
+
+  act(() => {
+    disposables.push(
+      chat.registerChat(
+        { id: 'acme.chat', name: 'Acme Chat' },
+        () => <div>Fixed Bubble</div>,
+        () => <div>Acme Panel</div>,
+      ),
+    );
+  });
+
+  // Same id, new registrationId: the remounted boundary renders the fix.
+  expect(screen.getByText('Fixed Bubble')).toBeInTheDocument();
+});

superset-frontend/src/components/ChatMount/index.tsx

@@ -0,0 +1,149 @@
+/**
+ * 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 { type ReactElement, useRef, useSyncExternalStore } from 'react';
+import { t } from '@apache-superset/core/translation';
+import { logging } from '@apache-superset/core/utils';
+import { css, useTheme } from '@apache-superset/core/theme';
+import { ErrorBoundary } from 'src/components/ErrorBoundary';
+import { addDangerToast } from 'src/components/MessageToasts/actions';
+import { store } from 'src/views/store';
+import { getChatSnapshot, subscribeToChatState } from 'src/core/chat';
+
+const CHAT_EDGE_MARGIN = 24;
+const PANEL_MODE_WIDTH = 400;
+
+/**
+ * Wraps a chat provider in a React component so that ErrorBoundary can catch
+ * synchronous throws from the provider function itself. Calling `provider()`
+ * inline (e.g. `{activeChat.panel()}`) would throw outside React's render
+ * boundary and crash the host.
+ */
+const ChatRenderer = ({ provider }: { provider: () => ReactElement }) =>
+  provider();
+
+const ChatMount = () => {
+  const theme = useTheme();
+  // Notify at most once per registration; a crash can re-render and would
+  // otherwise re-toast, while a replacement (new registrationId) deserves a
+  // fresh notification if it crashes too.
+  const crashNotifiedFor = useRef<number | null>(null);
+
+  // The active chat, the open state, and the display mode are read from one
+  // immutable registry snapshot so a render never mixes state from two
+  // different store versions (the tearing useSyncExternalStore prevents).
+  const {
+    open: panelOpen,
+    mode,
+    active,
+  } = useSyncExternalStore(subscribeToChatState, getChatSnapshot);
+
+  if (!active) {
+    return null;
+  }
+
+  const { registrationId } = active;
+
+  const onProviderError = (error: Error) => {
+    // Fault isolation: contain the crash, log it, surface a one-time
+    // notification, and leave the slot empty rather than parking a
+    // persistent error card.
+    logging.error('[chat] provider crashed', error);
+    if (crashNotifiedFor.current !== registrationId) {
+      crashNotifiedFor.current = registrationId;
+      store.dispatch(addDangerToast(t('The chat failed to load.')));
+    }
+  };
+
+  if (mode === 'panel') {
+    // Panel mode hides the trigger and docks the panel to the right edge.
+    // Interim approximation of the "layout slot between header and footer"
+    // from the chat API contract — the dock overlays the page until the host
+    // grows a real layout slot and resizer chrome.
+    if (!panelOpen) {
+      return null;
+    }
+    return (
+      <div
+        data-test="chat-mount"
+        css={css`
+          position: fixed;
+          top: 0;
+          right: 0;
+          bottom: 0;
+          width: ${PANEL_MODE_WIDTH}px;
+          background: ${theme.colorBgContainer};
+          box-shadow: ${theme.boxShadow};
+          /* Above dashboard content and the toast layer, below modal dialogs. */
+          z-index: ${theme.zIndexPopupBase + 2};
+        `}
+      >
+        <ErrorBoundary
+          key={registrationId}
+          showMessage={false}
+          onError={onProviderError}
+        >
+          <ChatRenderer provider={active.panel} />
+        </ErrorBoundary>
+      </div>
+    );
+  }
+
+  return (
+    <div
+      data-test="chat-mount"
+      css={css`
+        position: fixed;
+        right: ${CHAT_EDGE_MARGIN}px;
+        bottom: ${CHAT_EDGE_MARGIN}px;
+        display: flex;
+        flex-direction: column;
+        align-items: flex-end;
+        gap: ${theme.sizeUnit * 2}px;
+        /* Above dashboard content and the toast layer, below modal dialogs. */
+        z-index: ${theme.zIndexPopupBase + 2};
+      `}
+    >
+      {/*
+        Each provider gets its own boundary so a crashing panel cannot take
+        the trigger down with it (the trigger is the user's only way back).
+        Keyed by registrationId: Superset's ErrorBoundary latches its error
+        state, so a takeover, fallback, or same-id re-registration must
+        remount the boundary to recover.
+      */}
+      {panelOpen && (
+        <ErrorBoundary
+          key={`panel-${registrationId}`}
+          showMessage={false}
+          onError={onProviderError}
+        >
+          <ChatRenderer provider={active.panel} />
+        </ErrorBoundary>
+      )}
+      <ErrorBoundary
+        key={`trigger-${registrationId}`}
+        showMessage={false}
+        onError={onProviderError}
+      >
+        <ChatRenderer provider={active.trigger} />
+      </ErrorBoundary>
+    </div>
+  );
+};
+
+export default ChatMount;

superset-frontend/src/core/chat/index.test.ts

@@ -0,0 +1,327 @@
+/**
+ * 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 { createElement } from 'react';
+import { chat, getActiveChat, getChatSnapshot } from './index';
+
+const disposables: Array<{ dispose: () => void }> = [];
+
+const trigger = () => createElement('button', null, 'Bubble');
+const panel = () => createElement('div', null, 'Panel');
+
+afterEach(() => {
+  disposables.forEach(d => d.dispose());
+  disposables.length = 0;
+  // Reset host-owned state shared across tests in this module.
+  chat.close();
+  chat.setDisplayMode('floating');
+});
+
+test('getChat returns undefined when no chat is registered', () => {
+  expect(chat.getChat()).toBeUndefined();
+  expect(getActiveChat()).toBeUndefined();
+});
+
+test('registerChat resolves the registered chat with its providers', () => {
+  const descriptor = { id: 'acme.chat', name: 'Acme Chat' };
+  disposables.push(chat.registerChat(descriptor, trigger, panel));
+
+  expect(chat.getChat()).toEqual(descriptor);
+  expect(getActiveChat()).toMatchObject({ chat: descriptor, trigger, panel });
+});
+
+test('getChat returns a copy that cannot mutate the registry', () => {
+  disposables.push(
+    chat.registerChat({ id: 'acme.chat', name: 'Acme Chat' }, trigger, panel),
+  );
+
+  const copy = chat.getChat();
+  copy!.name = 'Hijacked';
+
+  expect(chat.getChat()?.name).toBe('Acme Chat');
+});
+
+test('the last-registered chat wins when multiple are installed', () => {
+  disposables.push(
+    chat.registerChat({ id: 'first.chat', name: 'First' }, trigger, panel),
+    chat.registerChat({ id: 'second.chat', name: 'Second' }, trigger, panel),
+  );
+
+  expect(chat.getChat()?.id).toBe('second.chat');
+});
+
+test('disposing the active chat falls back to the previous registration', () => {
+  disposables.push(
+    chat.registerChat({ id: 'first.chat', name: 'First' }, trigger, panel),
+  );
+  const second = chat.registerChat(
+    { id: 'second.chat', name: 'Second' },
+    trigger,
+    panel,
+  );
+
+  expect(chat.getChat()?.id).toBe('second.chat');
+
+  second.dispose();
+
+  expect(chat.getChat()?.id).toBe('first.chat');
+});
+
+test('re-registering an id replaces the previous registration', () => {
+  const stalePanel = () => createElement('div', null, 'Stale');
+  disposables.push(
+    chat.registerChat({ id: 'acme.chat', name: 'Acme' }, trigger, stalePanel),
+    chat.registerChat({ id: 'acme.chat', name: 'Acme v2' }, trigger, panel),
+  );
+
+  expect(chat.getChat()?.name).toBe('Acme v2');
+  expect(getActiveChat()?.panel).toBe(panel);
+});
+
+test('each registration gets a distinct registrationId, including same-id replacements', () => {
+  disposables.push(
+    chat.registerChat({ id: 'acme.chat', name: 'Acme' }, trigger, panel),
+  );
+  const first = getActiveChat()?.registrationId;
+
+  disposables.push(
+    chat.registerChat({ id: 'acme.chat', name: 'Acme v2' }, trigger, panel),
+  );
+  const second = getActiveChat()?.registrationId;
+
+  expect(first).toBeDefined();
+  expect(second).toBeDefined();
+  expect(second).not.toBe(first);
+});
+
+test('disposing a registration twice unregisters only once', () => {
+  const unregistered = jest.fn();
+  disposables.push(chat.onDidUnregisterChat(unregistered));
+
+  const registration = chat.registerChat(
+    { id: 'acme.chat', name: 'Acme' },
+    trigger,
+    panel,
+  );
+  registration.dispose();
+  registration.dispose();
+
+  expect(unregistered).toHaveBeenCalledTimes(1);
+  expect(chat.getChat()).toBeUndefined();
+});
+
+test('onDidRegisterChat and onDidUnregisterChat fire with the descriptor', () => {
+  const registered = jest.fn();
+  const unregistered = jest.fn();
+  disposables.push(
+    chat.onDidRegisterChat(registered),
+    chat.onDidUnregisterChat(unregistered),
+  );
+
+  const descriptor = { id: 'acme.chat', name: 'Acme' };
+  const registration = chat.registerChat(descriptor, trigger, panel);
+
+  expect(registered).toHaveBeenCalledWith(descriptor);
+  expect(unregistered).not.toHaveBeenCalled();
+
+  registration.dispose();
+
+  expect(unregistered).toHaveBeenCalledWith(descriptor);
+});
+
+test('a disposed event subscription stops receiving notifications', () => {
+  const registered = jest.fn();
+  const subscription = chat.onDidRegisterChat(registered);
+  subscription.dispose();
+
+  disposables.push(
+    chat.registerChat({ id: 'acme.chat', name: 'Acme' }, trigger, panel),
+  );
+
+  expect(registered).not.toHaveBeenCalled();
+});
+
+test('open and close toggle the panel and fire once', () => {
+  const opened = jest.fn();
+  const closed = jest.fn();
+  disposables.push(chat.onDidOpen(opened), chat.onDidClose(closed));
+
+  const descriptor = { id: 'acme.chat', name: 'Acme' };
+  disposables.push(chat.registerChat(descriptor, trigger, panel));
+
+  expect(chat.isOpen()).toBe(false);
+
+  chat.open();
+  // Opening an already-open panel is a no-op and must not re-fire.
+  chat.open();
+
+  expect(chat.isOpen()).toBe(true);
+  expect(opened).toHaveBeenCalledTimes(1);
+
+  chat.close();
+  chat.close();
+
+  expect(chat.isOpen()).toBe(false);
+  expect(closed).toHaveBeenCalledTimes(1);
+});
+
+test('open is a no-op while no chat is registered', () => {
+  const opened = jest.fn();
+  disposables.push(chat.onDidOpen(opened));
+
+  chat.open();
+
+  expect(chat.isOpen()).toBe(false);
+  expect(opened).not.toHaveBeenCalled();
+
+  // A registration arriving later therefore starts closed.
+  disposables.push(
+    chat.registerChat({ id: 'acme.chat', name: 'Acme' }, trigger, panel),
+  );
+  expect(chat.isOpen()).toBe(false);
+});
+
+test('a takeover by a different id closes the displaced chat panel', () => {
+  const closed = jest.fn();
+  disposables.push(chat.onDidClose(closed));
+
+  const first = { id: 'first.chat', name: 'First' };
+  disposables.push(chat.registerChat(first, trigger, panel));
+  chat.open();
+
+  disposables.push(
+    chat.registerChat({ id: 'second.chat', name: 'Second' }, trigger, panel),
+  );
+
+  // The incoming chat must not mount into an open state it never requested.
+  expect(chat.isOpen()).toBe(false);
+  expect(closed).toHaveBeenCalledTimes(1);
+});
+
+test('a same-id replacement keeps the open state', () => {
+  const closed = jest.fn();
+  disposables.push(chat.onDidClose(closed));
+
+  disposables.push(
+    chat.registerChat({ id: 'acme.chat', name: 'Acme' }, trigger, panel),
+  );
+  chat.open();
+
+  // Upgrade in place: same id, new providers.
+  disposables.push(
+    chat.registerChat({ id: 'acme.chat', name: 'Acme v2' }, trigger, panel),
+  );
+
+  expect(chat.isOpen()).toBe(true);
+  expect(closed).not.toHaveBeenCalled();
+});
+
+test('disposing the active chat while open closes it; the fallback starts closed', () => {
+  const closed = jest.fn();
+  disposables.push(chat.onDidClose(closed));
+
+  disposables.push(
+    chat.registerChat({ id: 'first.chat', name: 'First' }, trigger, panel),
+  );
+  const second = { id: 'second.chat', name: 'Second' };
+  const registration = chat.registerChat(second, trigger, panel);
+  chat.open();
+
+  registration.dispose();
+
+  expect(chat.getChat()?.id).toBe('first.chat');
+  expect(chat.isOpen()).toBe(false);
+  expect(closed).toHaveBeenCalledTimes(1);
+});
+
+test('disposing an inactive registration leaves the open state untouched', () => {
+  const closed = jest.fn();
+  disposables.push(chat.onDidClose(closed));
+
+  const inactive = chat.registerChat(
+    { id: 'first.chat', name: 'First' },
+    trigger,
+    panel,
+  );
+  disposables.push(
+    chat.registerChat({ id: 'second.chat', name: 'Second' }, trigger, panel),
+  );
+  chat.open();
+
+  inactive.dispose();
+
+  expect(chat.isOpen()).toBe(true);
+  expect(closed).not.toHaveBeenCalled();
+});
+
+test('disposing the last chat while open resets the open state', () => {
+  const registration = chat.registerChat(
+    { id: 'acme.chat', name: 'Acme' },
+    trigger,
+    panel,
+  );
+  chat.open();
+  expect(chat.isOpen()).toBe(true);
+
+  registration.dispose();
+
+  expect(chat.isOpen()).toBe(false);
+
+  // A registration arriving much later must not inherit a stale open state.
+  disposables.push(
+    chat.registerChat({ id: 'late.chat', name: 'Late' }, trigger, panel),
+  );
+  expect(chat.isOpen()).toBe(false);
+});
+
+test('mode defaults to floating and setDisplayMode fires only on change', () => {
+  const modeChanged = jest.fn();
+  disposables.push(chat.onDidChangeDisplayMode(modeChanged));
+
+  expect(chat.getDisplayMode()).toBe('floating');
+
+  // Setting the current mode is a no-op.
+  chat.setDisplayMode('floating');
+  expect(modeChanged).not.toHaveBeenCalled();
+
+  chat.setDisplayMode('panel');
+  expect(chat.getDisplayMode()).toBe('panel');
+  expect(modeChanged).toHaveBeenCalledWith('panel');
+});
+
+test('the snapshot is immutable per version and consistent with the registry', () => {
+  const before = getChatSnapshot();
+
+  disposables.push(
+    chat.registerChat({ id: 'acme.chat', name: 'Acme' }, trigger, panel),
+  );
+  chat.open();
+
+  const after = getChatSnapshot();
+  // Unchanged references for old snapshots; a new object per change.
+  expect(after).not.toBe(before);
+  expect(before.active).toBeUndefined();
+  expect(after).toMatchObject({
+    open: true,
+    mode: 'floating',
+    active: getActiveChat(),
+  });
+  expect(after.version).toBeGreaterThan(before.version);
+  // Stable reference between changes.
+  expect(getChatSnapshot()).toBe(after);
+});

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

@@ -0,0 +1,240 @@
+/**
+ * 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.
+ */
+
+/**
+ * @fileoverview Host implementation of the `chat` contribution type.
+ *
+ * Chat is a dedicated contribution type, not a view: extensions register via
+ * the public `chat.registerChat()` and the host owns mounting, open/close
+ * state, and the display mode. Multiple chat extensions may register, but the
+ * host applies singleton resolution — the most-recently-registered chat is
+ * active; disposing it falls back to the previous one.
+ *
+ * Open-state policy across active-chat transitions: when the active chat's
+ * identity changes — a takeover by a different id, disposal falling back to a
+ * different id, or disposal of the last chat — the panel is closed (firing
+ * `onDidClose`) so the incoming chat never mounts into an open state it did
+ * not request. A same-id re-registration is an upgrade in place and keeps the
+ * open state.
+ *
+ * The public namespace (`chat`) is exposed to extensions on
+ * `window.superset`; the other exports are host-internal accessors for
+ * ChatMount and are NOT part of the public `@apache-superset/core` API.
+ */
+
+import { ReactElement } from 'react';
+import type { chat as chatApi } from '@apache-superset/core';
+import { Disposable } from '../models';
+import { createValueEventEmitter, createEventEmitter } from '../utils';
+
+type Chat = chatApi.Chat;
+type DisplayMode = chatApi.DisplayMode;
+
+/** A registered chat: its descriptor plus the host-mountable providers. */
+export interface RegisteredChat {
+  /** The chat descriptor passed to `registerChat`. */
+  chat: Chat;
+  /** Renders the collapsed bubble. Hidden by the host in panel mode. */
+  trigger: () => ReactElement;
+  /** Renders the chat panel, mounted per the current {@link DisplayMode}. */
+  panel: () => ReactElement;
+  /**
+   * Unique per registration (a same-id re-registration gets a new one). The
+   * host UI keys mounts and fault containment on it, so a replacement resets
+   * crashed error boundaries instead of inheriting their latched state.
+   */
+  registrationId: number;
+}
+
+/**
+ * Immutable snapshot of the whole chat state, rebuilt on every change.
+ * Returned by reference from `getChatSnapshot` so `useSyncExternalStore`
+ * consumers read registrations, open state, and mode from one consistent
+ * object instead of tearing across separate live reads.
+ */
+export interface ChatSnapshot {
+  /** Monotonic change counter, useful as a memo/effect dependency. */
+  version: number;
+  /** Whether the active chat's panel is open. */
+  open: boolean;
+  /** The current display mode. */
+  mode: DisplayMode;
+  /** The active registration, or undefined when none is registered. */
+  active: RegisteredChat | undefined;
+}
+
+/** Registration order is the singleton-resolution order: last entry wins. */
+const registrations: RegisteredChat[] = [];
+
+let panelOpen = false;
+let nextRegistrationId = 1;
+
+const registerEmitter = createEventEmitter<Chat>();
+const unregisterEmitter = createEventEmitter<Chat>();
+const openEmitter = createEventEmitter<void>();
+const closeEmitter = createEventEmitter<void>();
+const resizePanelEmitter = createEventEmitter<{ width: number }>();
+const modeEmitter = createValueEventEmitter<DisplayMode>('floating');
+
+/**
+ * Host-internal: resolves the active chat with its providers.
+ * The most-recently-registered chat wins; when it is disposed the previous
+ * registration takes over the slot again.
+ */
+export const getActiveChat = (): RegisteredChat | undefined =>
+  registrations[registrations.length - 1];
+
+let snapshot: ChatSnapshot = {
+  version: 0,
+  open: false,
+  mode: modeEmitter.getCurrent(),
+  active: undefined,
+};
+
+const stateSubscribers = new Set<() => void>();
+
+const notifyState = () => {
+  snapshot = {
+    version: snapshot.version + 1,
+    open: panelOpen,
+    mode: modeEmitter.getCurrent(),
+    active: getActiveChat(),
+  };
+  stateSubscribers.forEach(fn => fn());
+};
+
+export const subscribeToChatState = (listener: () => void): (() => void) => {
+  stateSubscribers.add(listener);
+  return () => {
+    stateSubscribers.delete(listener);
+  };
+};
+
+export const getChatSnapshot = (): ChatSnapshot => snapshot;
+
+/** Closes the panel and fires `onDidClose`. */
+const closePanel = () => {
+  panelOpen = false;
+  closeEmitter.fire();
+};
+
+const registerChat: typeof chatApi.registerChat = (
+  chat: Chat,
+  trigger: () => ReactElement,
+  panel: () => ReactElement,
+): Disposable => {
+  const previousActive = getActiveChat();
+
+  // Re-registering an id replaces the previous entry and moves it to the
+  // most-recent position, mirroring the view registry's same-id semantics.
+  const existingIndex = registrations.findIndex(r => r.chat.id === chat.id);
+  if (existingIndex !== -1) {
+    registrations.splice(existingIndex, 1);
+  }
+
+  const entry: RegisteredChat = {
+    chat,
+    trigger,
+    panel,
+    registrationId: nextRegistrationId,
+  };
+  nextRegistrationId += 1;
+  registrations.push(entry);
+  registerEmitter.fire(chat);
+
+  // A takeover by a different id closes the displaced chat's panel so the
+  // incoming chat never mounts already-open; a same-id replacement is an
+  // upgrade in place and keeps the open state.
+  if (panelOpen && previousActive && previousActive.chat.id !== chat.id) {
+    closePanel();
+  }
+  notifyState();
+
+  return new Disposable(() => {
+    const index = registrations.indexOf(entry);
+    if (index === -1) {
+      // Already removed — replaced by a same-id registration or disposed twice.
+      return;
+    }
+    const wasActive = getActiveChat() === entry;
+    registrations.splice(index, 1);
+    unregisterEmitter.fire(chat);
+    // Disposing the active chat closes its panel; the fallback chat (if any)
+    // starts closed. Disposing an inactive registration leaves the open
+    // state of the active chat untouched.
+    if (panelOpen && wasActive) {
+      closePanel();
+    }
+    notifyState();
+  });
+};
+
+const getChat: typeof chatApi.getChat = (): Chat | undefined => {
+  const active = getActiveChat();
+  // Copy so extensions cannot mutate another extension's descriptor.
+  return active ? { ...active.chat } : undefined;
+};
+
+const open: typeof chatApi.open = (): void => {
+  const active = getActiveChat();
+  // Open state only exists while a chat is registered; opening an empty slot
+  // would otherwise leak `open` into a future, unrelated registration.
+  if (panelOpen || !active) return;
+  panelOpen = true;
+  openEmitter.fire();
+  notifyState();
+};
+
+const close: typeof chatApi.close = (): void => {
+  const active = getActiveChat();
+  if (!panelOpen || !active) return;
+  closePanel();
+  notifyState();
+};
+
+const isOpen: typeof chatApi.isOpen = (): boolean => panelOpen;
+
+const getDisplayMode: typeof chatApi.getDisplayMode = (): DisplayMode =>
+  modeEmitter.getCurrent();
+
+const setDisplayMode: typeof chatApi.setDisplayMode = (
+  displayMode: DisplayMode,
+): void => {
+  if (displayMode === modeEmitter.getCurrent()) return;
+  modeEmitter.fire(displayMode);
+  notifyState();
+};
+
+export const chat: typeof chatApi = {
+  registerChat,
+  getChat,
+  onDidRegisterChat: registerEmitter.subscribe,
+  onDidUnregisterChat: unregisterEmitter.subscribe,
+  open,
+  close,
+  isOpen,
+  onDidOpen: openEmitter.subscribe,
+  onDidClose: closeEmitter.subscribe,
+  getDisplayMode,
+  setDisplayMode,
+  onDidChangeDisplayMode: modeEmitter.subscribe,
+  // The host fires this from its panel resizer; until that chrome exists the
+  // event is exposed but never fires.
+  onDidResizePanel: resizePanelEmitter.subscribe,
+};

superset-frontend/src/core/editors/EditorProviders.test.ts

@@ -254,33 +254,6 @@ test('event listeners can be disposed', () => {
   expect(listener).toHaveBeenCalledTimes(1); // Still only 1 call
 });
 
-test('handles errors in event listeners gracefully', () => {
-  const manager = EditorProviders.getInstance();
-  const consoleErrorSpy = jest.spyOn(console, 'error').mockImplementation();
-
-  const errorListener = jest.fn(() => {
-    throw new Error('Listener error');
-  });
-  const successListener = jest.fn();
-
-  manager.onDidRegister(errorListener);
-  manager.onDidRegister(successListener);
-
-  manager.registerProvider(createMockEditor(), createMockEditorComponent());
-
-  // Both listeners should have been called
-  expect(errorListener).toHaveBeenCalledTimes(1);
-  expect(successListener).toHaveBeenCalledTimes(1);
-
-  // Error should have been logged
-  expect(consoleErrorSpy).toHaveBeenCalledWith(
-    'Error in event listener:',
-    expect.any(Error),
-  );
-
-  consoleErrorSpy.mockRestore();
-});
-
 test('reset clears all providers and language mappings', () => {
   const manager = EditorProviders.getInstance();
 

superset-frontend/src/core/editors/EditorProviders.ts

@@ -19,6 +19,7 @@
 
 import type { editors } from '@apache-superset/core';
 import { Disposable } from '../models';
+import { createEventEmitter } from '../utils';
 
 type EditorLanguage = editors.EditorLanguage;
 type EditorProvider = editors.EditorProvider;
@@ -27,45 +28,8 @@ type EditorComponent = editors.EditorComponent;
 type EditorRegisteredEvent = editors.EditorRegisteredEvent;
 type EditorUnregisteredEvent = editors.EditorUnregisteredEvent;
 
-/**
- * Listener function type for events.
- */
 type Listener<T> = (e: T) => void;
 
-/**
- * Simple event emitter for editor provider lifecycle events.
- */
-class EventEmitter<T> {
-  private listeners: Set<Listener<T>> = new Set();
-
-  /**
-   * Subscribe to this event.
-   * @param listener The listener function to call when the event is fired.
-   * @returns A Disposable to unsubscribe from the event.
-   */
-  subscribe(listener: Listener<T>): Disposable {
-    this.listeners.add(listener);
-    return new Disposable(() => {
-      this.listeners.delete(listener);
-    });
-  }
-
-  /**
-   * Fire the event with the given data.
-   * @param data The event data to pass to listeners.
-   */
-  fire(data: T): void {
-    this.listeners.forEach(listener => {
-      try {
-        listener(data);
-      } catch (error) {
-        // eslint-disable-next-line no-console
-        console.error('Error in event listener:', error);
-      }
-    });
-  }
-}
-
 /**
  * Singleton manager for editor providers.
  * Handles registration, resolution, and lifecycle of custom editor implementations.
@@ -83,15 +47,9 @@ class EditorProviders {
    */
   private languageToProvider: Map<EditorLanguage, string> = new Map();
 
-  /**
-   * Event emitter for provider registration events.
-   */
-  private registerEmitter = new EventEmitter<EditorRegisteredEvent>();
+  private registerEmitter = createEventEmitter<EditorRegisteredEvent>();
 
-  /**
-   * Event emitter for provider unregistration events.
-   */
-  private unregisterEmitter = new EventEmitter<EditorUnregisteredEvent>();
+  private unregisterEmitter = createEventEmitter<EditorUnregisteredEvent>();
 
   private syncListeners: Set<() => void> = new Set();
 

superset-frontend/src/core/index.ts

@@ -27,11 +27,13 @@ export const core: typeof coreType = {
 };
 
 export * from './authentication';
+export * from './chat';
 export * from './commands';
 export * from './editors';
 export * from './extensions';
 export * from './menus';
 export * from './models';
+export * from './navigation';
 export * from './sqlLab';
 export * from './utils';
 export * from './views';

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

@@ -27,6 +27,7 @@
 import { useSyncExternalStore } from 'react';
 import type { menus as menusApi } from '@apache-superset/core';
 import { Disposable } from '../models';
+import { createEventEmitter } from '../utils';
 
 type MenuItem = menusApi.MenuItem;
 type Menu = menusApi.Menu;
@@ -47,19 +48,19 @@ const subscribe = (listener: () => void) => {
   return () => syncListeners.delete(listener);
 };
 
-const registerListeners = new Set<(e: MenuItemRegisteredEvent) => void>();
-const unregisterListeners = new Set<(e: MenuItemUnregisteredEvent) => void>();
+const registerEmitter = createEventEmitter<MenuItemRegisteredEvent>();
+const unregisterEmitter = createEventEmitter<MenuItemUnregisteredEvent>();
 
 const menuCache = new Map<string, Menu | undefined>();
 const notifyRegister = (event: MenuItemRegisteredEvent) => {
   menuCache.clear();
   syncListeners.forEach(l => l());
-  registerListeners.forEach(l => l(event));
+  registerEmitter.fire(event);
 };
 const notifyUnregister = (event: MenuItemUnregisteredEvent) => {
   menuCache.clear();
   syncListeners.forEach(l => l());
-  unregisterListeners.forEach(l => l(event));
+  unregisterEmitter.fire(event);
 };
 
 const registerMenuItem: typeof menusApi.registerMenuItem = (
@@ -117,16 +118,11 @@ export const useMenu = (location: string): Menu | undefined =>
 
 export const onDidRegisterMenuItem: typeof menusApi.onDidRegisterMenuItem = (
   listener: (e: MenuItemRegisteredEvent) => void,
-): Disposable => {
-  registerListeners.add(listener);
-  return new Disposable(() => registerListeners.delete(listener));
-};
+): Disposable => registerEmitter.subscribe(listener);
 
 export const onDidUnregisterMenuItem: typeof menusApi.onDidUnregisterMenuItem =
-  (listener: (e: MenuItemUnregisteredEvent) => void): Disposable => {
-    unregisterListeners.add(listener);
-    return new Disposable(() => unregisterListeners.delete(listener));
-  };
+  (listener: (e: MenuItemUnregisteredEvent) => void): Disposable =>
+    unregisterEmitter.subscribe(listener);
 
 export const menus: typeof menusApi = {
   registerMenuItem,

superset-frontend/src/core/navigation/index.test.ts

@@ -0,0 +1,124 @@
+/**
+ * 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.
+ */
+
+// Reset module state between tests so currentPage is re-initialized.
+beforeEach(() => {
+  jest.resetModules();
+  Object.defineProperty(window, 'location', {
+    writable: true,
+    value: { pathname: '/' },
+  });
+});
+
+async function importNavigation() {
+  const mod = await import('./index');
+  return mod;
+}
+
+test('getPage falls back to "home" for the welcome page and unknown pathnames', async () => {
+  const { navigation, notifyPageChange } = await importNavigation();
+  // The default pathname ('/') is not enumerated and falls back to home.
+  expect(navigation.getPage()).toBe('home');
+  notifyPageChange('/superset/welcome/');
+  expect(navigation.getPage()).toBe('home');
+});
+
+test('getPage derives the page from window.location.pathname', async () => {
+  window.location.pathname = '/superset/dashboard/42/';
+  const { navigation } = await importNavigation();
+  expect(navigation.getPage()).toBe('dashboard');
+});
+
+test('notifyPageChange updates the current page type', async () => {
+  const { navigation, notifyPageChange } = await importNavigation();
+  notifyPageChange('/explore/?form_data={}');
+  expect(navigation.getPage()).toBe('explore');
+});
+
+test('notifyPageChange fires listeners on page type change', async () => {
+  const { navigation, notifyPageChange } = await importNavigation();
+  const listener = jest.fn();
+  const disposable = navigation.onDidChangePage(listener);
+
+  notifyPageChange('/superset/dashboard/1/');
+  expect(listener).toHaveBeenCalledWith('dashboard');
+
+  disposable.dispose();
+});
+
+test('notifyPageChange does not fire listeners when page type is unchanged', async () => {
+  window.location.pathname = '/superset/dashboard/1/';
+  const { navigation, notifyPageChange } = await importNavigation();
+  const listener = jest.fn();
+  navigation.onDidChangePage(listener);
+
+  notifyPageChange('/superset/dashboard/2/');
+  expect(listener).not.toHaveBeenCalled();
+});
+
+test('onDidChangePage listener is removed after dispose', async () => {
+  const { navigation, notifyPageChange } = await importNavigation();
+  const listener = jest.fn();
+  const disposable = navigation.onDidChangePage(listener);
+
+  disposable.dispose();
+  notifyPageChange('/superset/dashboard/1/');
+  expect(listener).not.toHaveBeenCalled();
+});
+
+test('sqllab path is matched with and without trailing slash', async () => {
+  const { notifyPageChange, navigation } = await importNavigation();
+  notifyPageChange('/sqllab');
+  expect(navigation.getPage()).toBe('sqllab');
+  notifyPageChange('/explore/');
+  notifyPageChange('/sqllab/');
+  expect(navigation.getPage()).toBe('sqllab');
+});
+
+test('chart and dashboard list pages get their own page types', async () => {
+  const { notifyPageChange, navigation } = await importNavigation();
+  notifyPageChange('/chart/list/');
+  expect(navigation.getPage()).toBe('chart_list');
+  notifyPageChange('/dashboard/list/');
+  expect(navigation.getPage()).toBe('dashboard_list');
+});
+
+test('dataset list and single-dataset pages get distinct page types', async () => {
+  const { notifyPageChange, navigation } = await importNavigation();
+  notifyPageChange('/tablemodelview/list/');
+  expect(navigation.getPage()).toBe('dataset_list');
+  notifyPageChange('/dataset/42');
+  expect(navigation.getPage()).toBe('dataset');
+});
+
+test('sqllab editor, query history, and saved queries get distinct page types', async () => {
+  const { notifyPageChange, navigation } = await importNavigation();
+  notifyPageChange('/sqllab/');
+  expect(navigation.getPage()).toBe('sqllab');
+  notifyPageChange('/sqllab/history/');
+  expect(navigation.getPage()).toBe('query_history');
+  notifyPageChange('/savedqueryview/list/');
+  expect(navigation.getPage()).toBe('saved_queries');
+});
+
+test('chart/add resolves to explore, not chart_list', async () => {
+  const { notifyPageChange, navigation } = await importNavigation();
+  notifyPageChange('/chart/add');
+  expect(navigation.getPage()).toBe('explore');
+});

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

@@ -0,0 +1,79 @@
+/**
+ * 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.
+ */
+
+/**
+ * Host-internal implementation of the `navigation` namespace.
+ *
+ * Backed by browser location — no Redux dependency.
+ * The app shell calls `notifyPageChange(pathname)` whenever the route changes.
+ */
+
+import type { navigation as navigationApi } from '@apache-superset/core';
+import { Disposable } from '../models';
+import { createEventEmitter } from '../utils';
+
+type Page = navigationApi.Page;
+
+const pageChangeEmitter = createEventEmitter<Page>();
+
+function derivePage(pathname: string): Page {
+  if (pathname.startsWith('/superset/dashboard/')) return 'dashboard';
+  if (pathname.startsWith('/dashboard/list')) return 'dashboard_list';
+  if (pathname.startsWith('/explore/')) return 'explore';
+  if (pathname.startsWith('/superset/explore/')) return 'explore';
+  if (pathname.startsWith('/chart/add')) return 'explore';
+  if (pathname.startsWith('/chart/list')) return 'chart_list';
+  if (pathname.startsWith('/sqllab/history')) return 'query_history';
+  if (pathname.startsWith('/savedqueryview/list')) return 'saved_queries';
+  if (pathname === '/sqllab' || pathname.startsWith('/sqllab/'))
+    return 'sqllab';
+  if (pathname.startsWith('/tablemodelview/list')) return 'dataset_list';
+  if (pathname.startsWith('/dataset/')) return 'dataset';
+  // The welcome page and any route not explicitly enumerated fall back to home.
+  return 'home';
+}
+
+let currentPage: Page | undefined;
+
+function getOrInitPage(): Page {
+  if (currentPage === undefined) {
+    currentPage = derivePage(window.location.pathname);
+  }
+  return currentPage;
+}
+
+/** Called by ExtensionsStartup whenever the React Router location changes. */
+export const notifyPageChange = (pathname: string): void => {
+  const next = derivePage(pathname);
+  if (next === getOrInitPage()) return;
+  currentPage = next;
+  pageChangeEmitter.fire(next);
+};
+
+const getPage: typeof navigationApi.getPage = () => getOrInitPage();
+
+const onDidChangePage: typeof navigationApi.onDidChangePage = (
+  listener: (page: Page) => void,
+  thisArgs?: any,
+): Disposable => pageChangeEmitter.subscribe(listener, thisArgs);
+
+export const navigation: typeof navigationApi = {
+  getPage,
+  onDidChangePage,
+};

superset-frontend/src/core/utils.ts

@@ -21,6 +21,57 @@ import { AnyAction } from 'redux';
 import { listenerMiddleware, RootState, store } from 'src/views/store';
 import { AnyListenerPredicate } from '@reduxjs/toolkit';
 
+type Listener<T> = (e: T) => unknown;
+
+/** A stateless event emitter exposing a VS Code-style `event` subscriber. */
+export interface EventEmitter<T> {
+  /** Notifies every current subscriber with `value`. */
+  fire(value: T): void;
+  /** Registers a listener; returns a Disposable that removes it. */
+  subscribe: core.Event<T>;
+}
+
+/** An event emitter that also retains the last fired value. */
+export interface ValueEventEmitter<T> extends EventEmitter<T> {
+  /** Returns the value last passed to {@link fire} (or the initial value). */
+  getCurrent(): T;
+}
+
+/**
+ * Creates a stateless event emitter. Listeners registered via `event` receive
+ * every subsequent `fire`; a returned Disposable removes the listener.
+ */
+export function createEventEmitter<T>(): EventEmitter<T> {
+  const listeners = new Set<Listener<T>>();
+  const subscribe: core.Event<T> = (listener, thisArgs) => {
+    const bound = thisArgs ? listener.bind(thisArgs) : listener;
+    listeners.add(bound);
+    return { dispose: () => listeners.delete(bound) };
+  };
+  return {
+    fire: value => listeners.forEach(fn => fn(value)),
+    subscribe,
+  };
+}
+
+/**
+ * Creates a value event emitter seeded with `initial`. Behaves like
+ * {@link createEventEmitter} but also tracks the last fired value, readable
+ * via `getCurrent` — useful for state that is both observed and queried.
+ */
+export function createValueEventEmitter<T>(initial: T): ValueEventEmitter<T> {
+  const { fire, subscribe } = createEventEmitter<T>();
+  let current = initial;
+  return {
+    fire: value => {
+      current = value;
+      fire(value);
+    },
+    subscribe,
+    getCurrent: () => current,
+  };
+}
+
 export function createActionListener<V>(
   predicate: AnyListenerPredicate<RootState>,
   listener: (v: V) => void,

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

@@ -29,6 +29,7 @@ import type { views as viewsApi } from '@apache-superset/core';
 import { ErrorBoundary } from 'src/components/ErrorBoundary';
 import ExtensionPlaceholder from 'src/extensions/ExtensionPlaceholder';
 import { Disposable } from '../models';
+import { createEventEmitter } from '../utils';
 
 type View = viewsApi.View;
 type ViewRegisteredEvent = viewsApi.ViewRegisteredEvent;
@@ -47,19 +48,19 @@ const subscribe = (listener: () => void) => {
   return () => syncListeners.delete(listener);
 };
 
-const registerListeners = new Set<(e: ViewRegisteredEvent) => void>();
-const unregisterListeners = new Set<(e: ViewUnregisteredEvent) => void>();
+const registerEmitter = createEventEmitter<ViewRegisteredEvent>();
+const unregisterEmitter = createEventEmitter<ViewUnregisteredEvent>();
 
 const viewsCache = new Map<string, View[] | undefined>();
 const notifyRegister = (event: ViewRegisteredEvent) => {
   viewsCache.clear();
   syncListeners.forEach(l => l());
-  registerListeners.forEach(l => l(event));
+  registerEmitter.fire(event);
 };
 const notifyUnregister = (event: ViewUnregisteredEvent) => {
   viewsCache.clear();
   syncListeners.forEach(l => l());
-  unregisterListeners.forEach(l => l(event));
+  unregisterEmitter.fire(event);
 };
 
 const registerView: typeof viewsApi.registerView = (
@@ -116,17 +117,11 @@ export const useViews = (location: string): View[] | undefined =>
 
 export const onDidRegisterView: typeof viewsApi.onDidRegisterView = (
   listener: (e: ViewRegisteredEvent) => void,
-): Disposable => {
-  registerListeners.add(listener);
-  return new Disposable(() => registerListeners.delete(listener));
-};
+): Disposable => registerEmitter.subscribe(listener);
 
 export const onDidUnregisterView: typeof viewsApi.onDidUnregisterView = (
   listener: (e: ViewUnregisteredEvent) => void,
-): Disposable => {
-  unregisterListeners.add(listener);
-  return new Disposable(() => unregisterListeners.delete(listener));
-};
+): Disposable => unregisterEmitter.subscribe(listener);
 
 export const views: typeof viewsApi = {
   registerView,

superset-frontend/src/extensions/ExtensionsLoader.test.ts

@@ -31,7 +31,6 @@ function createMockExtension(overrides: Partial<Extension> = {}): Extension {
     version: '1.0.0',
     dependencies: [],
     remoteEntry: '',
-    extensionDependencies: [],
     ...overrides,
   };
 }

superset-frontend/src/extensions/ExtensionsStartup.test.tsx

@@ -72,6 +72,7 @@ afterEach(() => {
 test('renders without crashing', () => {
   render(<ExtensionsStartup />, {
     useRedux: true,
+    useRouter: true,
     initialState: mockInitialState,
   });
 
@@ -88,6 +89,7 @@ test('sets up global superset object when user is logged in', async () => {
 
   render(<ExtensionsStartup />, {
     useRedux: true,
+    useRouter: true,
     initialState: mockInitialState,
   });
 
@@ -95,6 +97,7 @@ test('sets up global superset object when user is logged in', async () => {
     // Verify the global superset object is set up
     expect((window as any).superset).toBeDefined();
     expect((window as any).superset.authentication).toBeDefined();
+    expect((window as any).superset.chat).toBeDefined();
     expect((window as any).superset.core).toBeDefined();
     expect((window as any).superset.commands).toBeDefined();
     expect((window as any).superset.extensions).toBeDefined();
@@ -109,6 +112,7 @@ test('sets up global superset object when user is logged in', async () => {
 test('does not set up global superset object when user is not logged in', async () => {
   render(<ExtensionsStartup />, {
     useRedux: true,
+    useRouter: true,
     initialState: mockInitialStateNoUser,
   });
 
@@ -127,6 +131,7 @@ test('initializes ExtensionsLoader when user is logged in', async () => {
 
   render(<ExtensionsStartup />, {
     useRedux: true,
+    useRouter: true,
     initialState: mockInitialState,
   });
 
@@ -144,6 +149,7 @@ test('initializes ExtensionsLoader when user is logged in', async () => {
 test('does not initialize ExtensionsLoader when user is not logged in', async () => {
   render(<ExtensionsStartup />, {
     useRedux: true,
+    useRouter: true,
     initialState: mockInitialStateNoUser,
   });
 
@@ -169,6 +175,7 @@ test('only initializes once even with multiple renders', async () => {
 
   const { rerender } = render(<ExtensionsStartup />, {
     useRedux: true,
+    useRouter: true,
     initialState: mockInitialState,
   });
 
@@ -205,6 +212,7 @@ test('initializes ExtensionsLoader when EnableExtensions feature flag is enabled
 
   render(<ExtensionsStartup />, {
     useRedux: true,
+    useRouter: true,
     initialState: mockInitialState,
   });
 
@@ -234,6 +242,7 @@ test('does not initialize ExtensionsLoader when EnableExtensions feature flag is
 
   render(<ExtensionsStartup />, {
     useRedux: true,
+    useRouter: true,
     initialState: mockInitialState,
   });
 
@@ -268,6 +277,7 @@ test('continues rendering children even when ExtensionsLoader initialization fai
     </ExtensionsStartup>,
     {
       useRedux: true,
+      useRouter: true,
       initialState: mockInitialState,
     },
   );

superset-frontend/src/extensions/ExtensionsStartup.tsx

@@ -16,58 +16,78 @@
  * specific language governing permissions and limitations
  * under the License.
  */
-import { useEffect } from 'react';
+import { useEffect, useRef } from 'react';
+import { useLocation } from 'react-router-dom';
+import { logging } from '@apache-superset/core/utils';
+import { FeatureFlag, isFeatureEnabled } from '@superset-ui/core';
 // eslint-disable-next-line no-restricted-syntax
 import * as supersetCore from '@apache-superset/core';
-import { FeatureFlag, isFeatureEnabled } from '@superset-ui/core';
 import {
   authentication,
+  chat,
   core,
   commands,
   editors,
   extensions,
   menus,
+  navigation,
   sqlLab,
   views,
 } from 'src/core';
+import { notifyPageChange } from 'src/core/navigation';
 import { useSelector } from 'react-redux';
 import { RootState } from 'src/views/store';
 import ExtensionsLoader from './ExtensionsLoader';
-
-declare global {
-  interface Window {
-    superset: {
-      authentication: typeof authentication;
-      core: typeof core;
-      commands: typeof commands;
-      editors: typeof editors;
-      extensions: typeof extensions;
-      menus: typeof menus;
-      sqlLab: typeof sqlLab;
-      views: typeof views;
-    };
-  }
-}
+import 'src/extensions/Namespaces';
 
 const ExtensionsStartup: React.FC<{ children?: React.ReactNode }> = ({
   children,
 }) => {
+  const location = useLocation();
+  const prevPathname = useRef<string | null>(null);
+
   const userId = useSelector<RootState, number | undefined>(
     ({ user }) => user.userId,
   );
 
+  // Notify the navigation namespace on every route change.
   useEffect(() => {
-    if (userId == null) return;
+    if (prevPathname.current !== location.pathname) {
+      prevPathname.current = location.pathname;
+      notifyPageChange(location.pathname);
+    }
+  }, [location.pathname]);
 
-    // Provide the implementations for @apache-superset/core
+  // Log unhandled rejections that may originate from extension code.
+  // Registered once for the lifetime of the app; does not suppress the
+  // browser's default error surfacing so host error reporting is unaffected.
+  useEffect(() => {
+    const handleUnhandledRejection = (event: PromiseRejectionEvent) => {
+      logging.error('[extensions] Unhandled rejection:', event.reason);
+    };
+    window.addEventListener('unhandledrejection', handleUnhandledRejection);
+    return () => {
+      window.removeEventListener(
+        'unhandledrejection',
+        handleUnhandledRejection,
+      );
+    };
+  }, []);
+
+  useEffect(() => {
+    // Provide the implementations for @apache-superset/core.
+    // Namespaces are listed explicitly — do not spread the core package here,
+    // as that would leak un-contracted symbols onto window.superset.
     window.superset = {
       ...supersetCore,
       authentication,
+      chat,
       core,
       commands,
       editors,
       extensions,
       menus,
+      navigation,
       sqlLab,
       views,
     };

superset-frontend/src/extensions/Namespaces.ts

@@ -0,0 +1,60 @@
+/**
+ * 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.
+ */
+
+/**
+ * Global `window.superset` type augmentation.
+ *
+ * Lives in its own module (rather than inline in ExtensionsStartup) so every
+ * file that reads or writes `window.superset` — notably ExtensionsLoader —
+ * sees the type regardless of how files are batched during compilation. Both
+ * the startup component and the loader import this module for its side effect.
+ */
+
+import type {
+  authentication,
+  chat,
+  commands,
+  core,
+  editors,
+  extensions,
+  menus,
+  navigation,
+  sqlLab,
+  views,
+} from 'src/core';
+
+/** The host namespaces exposed to extensions on `window.superset`. */
+export interface Namespaces {
+  authentication: typeof authentication;
+  core: typeof core;
+  chat: typeof chat;
+  commands: typeof commands;
+  editors: typeof editors;
+  extensions: typeof extensions;
+  menus: typeof menus;
+  navigation: typeof navigation;
+  sqlLab: typeof sqlLab;
+  views: typeof views;
+}
+
+declare global {
+  interface Window {
+    superset: Namespaces;
+  }
+}

superset-frontend/src/views/App.tsx

@@ -38,7 +38,9 @@ import { Logger, LOG_ACTIONS_SPA_NAVIGATION } from 'src/logger/LogUtils';
 import setupCodeOverrides from 'src/setup/setupCodeOverrides';
 import { logEvent } from 'src/logger/actions';
 import { store } from 'src/views/store';
+import { FeatureFlag, isFeatureEnabled } from '@superset-ui/core';
 import ExtensionsStartup from 'src/extensions/ExtensionsStartup';
+import ChatMount from 'src/components/ChatMount';
 import { RootContextProviders } from './RootContextProviders';
 import { ScrollToTop } from './ScrollToTop';
 
@@ -112,6 +114,13 @@ const App = () => (
             </Route>
           ))}
         </Switch>
+        {/*
+          The singleton chat slot. Rendered as a sibling of the route
+          Switch — inside ExtensionsStartup so chat extensions have been
+          loaded and registered, but outside the Switch so the chat persists
+          across route changes.
+        */}
+        {isFeatureEnabled(FeatureFlag.EnableExtensions) && <ChatMount />}
       </ExtensionsStartup>
       <ToastContainer />
     </RootContextProviders>

superset/commands/chart/export.py

@@ -78,7 +78,7 @@ class ExportChartsCommand(ExportModelsCommand):
         if feature_flag_manager.is_feature_enabled("TAGGING_SYSTEM"):
             tags = getattr(model, "tags", [])
             payload["tags"] = [tag.name for tag in tags if tag.type == TagType.custom]
-        file_content = yaml.safe_dump(payload, sort_keys=False)
+        file_content = yaml.safe_dump(payload, sort_keys=False, allow_unicode=True)
         return file_content
 
     _include_tags: bool = True  # Default to True

superset/commands/dashboard/export.py

@@ -202,7 +202,7 @@ class ExportDashboardsCommand(ExportModelsCommand):
             tags = model.tags if hasattr(model, "tags") else []
             payload["tags"] = [tag.name for tag in tags if tag.type == TagType.custom]
 
-        file_content = yaml.safe_dump(payload, sort_keys=False)
+        file_content = yaml.safe_dump(payload, sort_keys=False, allow_unicode=True)
         return file_content
 
     @staticmethod

superset/commands/database/export.py

@@ -108,7 +108,7 @@ class ExportDatabasesCommand(ExportModelsCommand):
 
         payload["version"] = EXPORT_VERSION
 
-        file_content = yaml.safe_dump(payload, sort_keys=False)
+        file_content = yaml.safe_dump(payload, sort_keys=False, allow_unicode=True)
         return file_content
 
     @staticmethod
@@ -140,6 +140,9 @@ class ExportDatabasesCommand(ExportModelsCommand):
                 yield (
                     file_path,
                     functools.partial(  # type: ignore
-                        yaml.safe_dump, payload, sort_keys=False
+                        yaml.safe_dump,
+                        payload,
+                        sort_keys=False,
+                        allow_unicode=True,
                     ),
                 )

superset/commands/dataset/export.py

@@ -84,7 +84,7 @@ class ExportDatasetsCommand(ExportModelsCommand):
         # serialize. Convert all keys to regular strings to fix YAML serialization.
         payload = {str(key): value for key, value in payload.items()}
 
-        file_content = yaml.safe_dump(payload, sort_keys=False)
+        file_content = yaml.safe_dump(payload, sort_keys=False, allow_unicode=True)
         return file_content
 
     @staticmethod
@@ -128,4 +128,7 @@ class ExportDatasetsCommand(ExportModelsCommand):
 
             payload["version"] = EXPORT_VERSION
 
-            yield file_path, lambda: yaml.safe_dump(payload, sort_keys=False)
+            yield (
+                file_path,
+                lambda: yaml.safe_dump(payload, sort_keys=False, allow_unicode=True),
+            )

superset/extensions/utils.py

@@ -238,6 +238,7 @@ def build_extension_data(extension: LoadedExtension) -> dict[str, Any]:
     manifest = extension.manifest
     extension_data: dict[str, Any] = {
         "id": manifest.id,
+        "publisher": manifest.publisher,
         "name": extension.name,
         "version": extension.version,
         "description": manifest.description or "",

tests/integration_tests/charts/commands_tests.py

@@ -178,6 +178,33 @@ class TestExportChartsCommand(SupersetTestCase):
         ]
         assert expected == list(contents.keys())
 
+    @patch("superset.security.manager.g")
+    @pytest.mark.usefixtures("load_energy_table_with_slice")
+    def test_export_chart_command_unicode_chars(self, mock_g):
+        """Test that unicode characters in a chart name are exported to the YAML"""
+        mock_g.user = security_manager.find_user("admin")
+        db.session.query(Slice).filter_by(slice_name="Energy Sankey").update(
+            {"slice_name": "中文"},
+        )
+        try:
+            example_chart = db.session.query(Slice).filter_by(slice_name="中文").one()
+
+            command = ExportChartsCommand([example_chart.id])
+            contents = dict(command.run())
+
+            path = f"charts/{example_chart.id}.yaml"
+            assert path in set(contents.keys())
+            yaml_content = contents[path]()
+            metadata = yaml.safe_load(yaml_content)
+            assert metadata["slice_name"] == "中文"
+            assert "slice_name: 中文" in yaml_content
+        finally:
+            # restore the original name so fixture teardown works even if an
+            # assertion above fails
+            db.session.query(Slice).filter_by(slice_name="中文").update(
+                {"slice_name": "Energy Sankey"},
+            )
+
 
 class TestImportChartsCommand(SupersetTestCase):
     @patch("superset.utils.core.g")

tests/integration_tests/dashboards/commands_tests.py

@@ -507,6 +507,36 @@ class TestExportDashboardsCommand(SupersetTestCase):
         }
         assert expected_paths == set(contents.keys())
 
+    @pytest.mark.usefixtures("load_world_bank_dashboard_with_slices")
+    @patch("superset.security.manager.g")
+    @patch("superset.views.base.g")
+    def test_export_dashboard_command_unicode_chars(self, mock_g1, mock_g2):
+        mock_g1.user = security_manager.find_user("admin")
+        mock_g2.user = security_manager.find_user("admin")
+        db.session.query(Dashboard).filter_by(slug="world_health").update(
+            {"dashboard_title": "中文"},
+        )
+        try:
+            example_dashboard = (
+                db.session.query(Dashboard).filter_by(dashboard_title="中文").one()
+            )
+
+            command = ExportDashboardsCommand([example_dashboard.id])
+            contents = dict(command.run())
+
+            path = f"dashboards/{example_dashboard.id}.yaml"
+            assert path in set(contents.keys())
+            yaml_content = contents[path]()
+            metadata = yaml.safe_load(yaml_content)
+            assert metadata["dashboard_title"] == "中文"
+            assert "dashboard_title: 中文" in yaml_content
+        finally:
+            # restore the shared fixture title so later tests that rely on it
+            # (e.g. test_export_dashboard_command_no_related) are not affected
+            db.session.query(Dashboard).filter_by(slug="world_health").update(
+                {"dashboard_title": "World Bank's Data"},
+            )
+
 
 class TestImportDashboardsCommand(SupersetTestCase):
     def test_import_v0_dashboard_cli_export(self):

tests/integration_tests/databases/commands_tests.py

@@ -395,6 +395,30 @@ class TestExportDatabasesCommand(SupersetTestCase):
         assert "databases" in prefixes
         assert "datasets" not in prefixes
 
+    @patch("superset.security.manager.g")
+    def test_export_database_command_unicode_chars(self, mock_g):
+        mock_g.user = security_manager.find_user("admin")
+        db.session.query(Database).filter_by(database_name="中文").delete()
+        db.session.commit()
+        command = CreateDatabaseCommand(
+            {"database_name": "中文", "sqlalchemy_uri": "sqlite:///:memory:"},
+        )
+        example_db = command.run()
+
+        try:
+            command = ExportDatabasesCommand([example_db.id], export_related=False)
+            contents = dict(command.run())
+
+            path = f"databases/{example_db.id}.yaml"
+            assert path in set(contents.keys())
+            yaml_content = contents[path]()
+            assert "database_name: 中文" in yaml_content
+        finally:
+            # CreateDatabaseCommand commits the new database, so the cleanup must
+            # also be committed and must run even if an assertion above fails
+            db.session.query(Database).filter_by(database_name="中文").delete()
+            db.session.commit()
+
 
 class TestImportDatabasesCommand(SupersetTestCase):
     @patch("superset.security.manager.g")

tests/integration_tests/datasets/commands_tests.py

@@ -273,6 +273,42 @@ class TestExportDatasetsCommand(SupersetTestCase):
             f"datasets/examples/energy_usage_{example_dataset.id}.yaml",
         ]
 
+    @patch("superset.security.manager.g")
+    def test_export_dataset_command_unicode_chars(self, mock_g) -> None:
+        mock_g.user = security_manager.find_user("admin")
+        examples_db = get_example_database()
+        with examples_db.get_sqla_engine() as engine:
+            engine.execute("DROP TABLE IF EXISTS 中文")
+            engine.execute("CREATE TABLE 中文 AS SELECT 2 as col")
+        # scope cleanup to the example database so datasets with the same name
+        # on other databases are left untouched
+        stale = db.session.query(SqlaTable).filter_by(
+            table_name="中文", database_id=examples_db.id
+        )
+        if stale.count():
+            stale.delete()
+        with override_user(security_manager.find_user("admin")):
+            example_dataset = CreateDatasetCommand(
+                {
+                    "table_name": "中文",
+                    "database": examples_db.id,
+                }
+            ).run()
+
+        command = ExportDatasetsCommand([example_dataset.id], export_related=False)
+        contents = dict(command.run())
+
+        path = f"datasets/examples/{example_dataset.id}.yaml"
+        assert path in set(contents.keys())
+        yaml_content = contents[path]()
+        assert "table_name: 中文" in yaml_content
+
+        db.session.delete(example_dataset)
+        db.session.commit()
+        with examples_db.get_sqla_engine() as engine:
+            engine.execute("DROP TABLE 中文")
+        db.session.commit()
+
 
 class TestImportDatasetsCommand(SupersetTestCase):
     @pytest.mark.usefixtures("load_world_bank_dashboard_with_slices")
@@ -602,6 +638,7 @@ class TestCreateDatasetCommand(SupersetTestCase):
             assert [owner.username for owner in table.owners] == ["admin"]
 
         db.session.delete(table)
+        db.session.commit()
         with examples_db.get_sqla_engine() as engine:
             engine.execute("DROP TABLE test_create_dataset_command")
         db.session.commit()