feat: convert capabilities to getter for subclass overrides (#447)

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<!-- CURSOR_SUMMARY -->
---

> [!NOTE]
> Makes keyring capabilities dynamically overridable.
> 
> - Change `KeyringWrapper.capabilities` from a readonly property to a
getter, enabling subclasses to compute capabilities at runtime
> - Update `QrKeyringV2` to override `capabilities` and return
mode-specific capabilities (ACCOUNT vs HD) instead of redefining the
property via `Object.defineProperty`
> - Update changelogs for `keyring-api` and `keyring-eth-qr` to document
the change
> 
> <sup>Written by [Cursor
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Author: mathieuartu

packages/keyring-api/CHANGELOG.md

@@ -19,6 +19,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Changed
 
+- Change `KeyringWrapper.capabilities` from a readonly property to a getter ([#447](https://github.com/MetaMask/accounts/pull/447))
+  - Allows subclasses to override and return capabilities dynamically based on runtime state.
 - Refine `EthAddressStruct` in order to make it compatible with the `Hex` type from `@metamask/utils` ([#405](https://github.com/MetaMask/accounts/pull/405))
 
 ## [21.3.0]

packages/keyring-api/src/api/v2/wrapper/keyring-wrapper.ts

@@ -51,7 +51,7 @@ export abstract class KeyringWrapper<
 {
   readonly type: `${KeyringType}`;
 
-  readonly capabilities: KeyringCapabilities;
+  readonly #capabilities: KeyringCapabilities;
 
   protected readonly inner: InnerKeyring;
 
@@ -74,7 +74,19 @@ export abstract class KeyringWrapper<
   constructor(options: KeyringWrapperOptions<InnerKeyring>) {
     this.inner = options.inner;
     this.type = `${options.type}`;
-    this.capabilities = options.capabilities;
+    this.#capabilities = options.capabilities;
+  }
+
+  /**
+   * Get the capabilities of this keyring.
+   *
+   * Subclasses can override this getter to return capabilities dynamically
+   * based on runtime state.
+   *
+   * @returns The keyring's capabilities.
+   */
+  get capabilities(): KeyringCapabilities {
+    return this.#capabilities;
   }
 
   /**

packages/keyring-eth-qr/CHANGELOG.md

@@ -9,7 +9,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Added
 
-- Add `QrKeyringV2` class implementing `KeyringV2` interface ([#411](https://github.com/MetaMask/accounts/pull/411))
+- Add `QrKeyringV2` class implementing `KeyringV2` interface ([#411](https://github.com/MetaMask/accounts/pull/411)), ([#447](https://github.com/MetaMask/accounts/pull/447))
   - Wraps legacy `QrKeyring` to expose accounts via the unified `KeyringV2` API and the `KeyringAccount` type.
   - Extends `EthKeyringWrapper` for common Ethereum logic.
 

packages/keyring-eth-qr/src/qr-keyring-v2.ts

@@ -104,22 +104,24 @@ export class QrKeyringV2
     super({
       type: KeyringType.Qr,
       inner: options.legacyKeyring,
-      // Placeholder - will be overridden by getter below
+      // Default capabilities - overridden by getter below
       capabilities: HD_MODE_CAPABILITIES,
     });
     this.entropySource = options.entropySource;
+  }
 
-    // Override the readonly capabilities property with a dynamic getter
-    // that returns capabilities based on the current device mode.
-    Object.defineProperty(this, 'capabilities', {
-      get: (): KeyringCapabilities => {
-        return this.inner.getMode() === DeviceMode.ACCOUNT
-          ? ACCOUNT_MODE_CAPABILITIES
-          : HD_MODE_CAPABILITIES;
-      },
-      enumerable: true,
-      configurable: false,
-    });
+  /**
+   * Get the capabilities of this keyring.
+   *
+   * Overrides the base class getter to return capabilities dynamically
+   * based on the current device mode.
+   *
+   * @returns The keyring's capabilities.
+   */
+  override get capabilities(): KeyringCapabilities {
+    return this.inner.getMode() === DeviceMode.ACCOUNT
+      ? ACCOUNT_MODE_CAPABILITIES
+      : HD_MODE_CAPABILITIES;
   }
 
   /**