diff --git a/core/field.ts b/core/field.ts
index 43558ce4090..391ab5ac84a 100644
--- a/core/field.ts
+++ b/core/field.ts
@@ -42,6 +42,7 @@ import * as userAgent from './utils/useragent.js';
 import * as utilsXml from './utils/xml.js';
 import * as WidgetDiv from './widgetdiv.js';
 import type {WorkspaceSvg} from './workspace_svg.js';
+import {ISerializable} from './interfaces/i_serializable.js';
 
 /**
  * A function that is called to validate changes to the field's value before
@@ -68,7 +69,7 @@ export type FieldValidator<T = any> = (newValue: T) => T|null|undefined;
 export abstract class Field<T = any> implements IASTNodeLocationSvg,
                                                 IASTNodeLocationWithBlock,
                                                 IKeyboardAccessible,
-                                                IRegistrable {
+                                                IRegistrable, ISerializable {
   /**
    * To overwrite the default value which is set in **Field**, directly update
    * the prototype.
diff --git a/core/interfaces/i_has_bubble.ts b/core/interfaces/i_has_bubble.ts
new file mode 100644
index 00000000000..f82f1a9dccb
--- /dev/null
+++ b/core/interfaces/i_has_bubble.ts
@@ -0,0 +1,20 @@
+/**
+ * @license
+ * Copyright 2023 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+
+export interface IHasBubble {
+  /** @return True if the bubble is currently open, false otherwise. */
+  isBubbleVisible(): boolean;
+
+  /** Sets whether the bubble is open or not. */
+  setBubbleVisible(visible: boolean): void;
+}
+
+/** Type guard that checks whether the given object is a IHasBubble. */
+export function hasBubble(obj: any): obj is IHasBubble {
+  return obj.isBubbleVisible !== undefined &&
+      obj.setBubbleVisible !== undefined;
+}
diff --git a/core/interfaces/i_icon.ts b/core/interfaces/i_icon.ts
new file mode 100644
index 00000000000..fa7dc345d20
--- /dev/null
+++ b/core/interfaces/i_icon.ts
@@ -0,0 +1,92 @@
+/**
+ * @license
+ * Copyright 2023 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import type {Coordinate} from '../utils/coordinate.js';
+import type {Size} from '../utils/size.js';
+
+
+export interface IIcon {
+  /**
+   * @return the string representing the type of the icon.
+   * E.g. 'comment', 'warning', etc. This string should also be used when
+   * registering the icon class.
+   */
+  getType(): string;
+
+  /**
+   * Creates the SVG elements for the icon that will live on the block.
+   *
+   * @param pointerdownListener An event listener that must be attached to the
+   *     root SVG element by the implementation of `initView`. Used by Blockly's
+   *     gesture system to properly handle clicks and drags.
+   */
+  initView(pointerdownListener: (e: PointerEvent) => void): void;
+
+  /**
+   * Disposes of any elements of the icon.
+   *
+   * @remarks
+   *
+   * In particular, if this icon is currently showing a bubble, this should be
+   * used to hide it.
+   */
+  dispose(): void;
+
+  /**
+   * @return the "weight" of the icon, which determines the static order which
+   *     icons should be rendered in. More positive numbers are rendered farther
+   *     toward the end of the block.
+   */
+  getWeight(): number;
+
+  /** @return The dimensions of the icon for use in rendering. */
+  getSize(): Size;
+
+  /** Notifies the icon that the block's colour has changed. */
+  applyColour(): void;
+
+  /** Notifies the icon that the block's editability has changed. */
+  updateEditable(): void;
+
+  /** Notifies the icon that the block's collapsed-ness has changed. */
+  updateCollapsed(): void;
+
+  /**
+   * @return Whether this icon is shown when the block is collapsed. Used
+   *     to allow renderers to account for padding.
+   */
+  isShownWhenCollapsed(): boolean;
+
+  /**
+   * Notifies the icon where it is relative to its block's top-start, in
+   * workspace units.
+   */
+  setOffsetInBlock(offset: Coordinate): void;
+
+  /**
+   * Notifies the icon that it has changed locations.
+   *
+   * @param blockOrigin The location of this icon's block's top-start corner
+   *     in workspace coordinates.
+   */
+  onLocationChange(blockOrigin: Coordinate): void;
+
+  /**
+   * Notifies the icon that it has been clicked.
+   */
+  onClick(): void;
+}
+
+/** Type guard that checks whether the given object is an IIcon. */
+export function isIcon(obj: any): obj is IIcon {
+  return obj.getType !== undefined && obj.initView !== undefined &&
+      obj.dispose !== undefined && obj.getWeight !== undefined &&
+      obj.getSize !== undefined && obj.applyColour !== undefined &&
+      obj.updateEditable !== undefined && obj.updateCollapsed !== undefined &&
+      obj.isShownWhenCollapsed !== undefined &&
+      obj.setOffsetInBlock !== undefined &&
+      obj.onLocationChange !== undefined && obj.onClick !== undefined;
+}
diff --git a/core/interfaces/i_serializable.ts b/core/interfaces/i_serializable.ts
new file mode 100644
index 00000000000..ad65cb3f026
--- /dev/null
+++ b/core/interfaces/i_serializable.ts
@@ -0,0 +1,29 @@
+/**
+ * @license
+ * Copyright 2023 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+
+export interface ISerializable {
+  /**
+   * @param doFullSerialization If true, this signals that any backing data
+   *     structures used by this ISerializable should also be serialized. This
+   *     is used for copy-paste.
+   * @return a JSON serializable value that records the icon's state.
+   */
+  saveState(doFullSerialization: boolean): any;
+
+  /**
+   * Takes in a JSON serializable value and sets the ISerializable's state
+   * based on that.
+   *
+   * @param state The state to apply to the ISerializable.
+   */
+  loadState(state: any): void;
+}
+
+/** Type guard that checks whether the given object is a ISerializable. */
+export function isSerializable(obj: any): obj is ISerializable {
+  return obj.saveState !== undefined && obj.loadState !== undefined;
+}