chore: add new method to list available entropy sources

Author: shane-t

SIPS/sip-30.md

@@ -14,7 +14,7 @@ This SIP proposes additions to entropy retrieval APIs that allows snaps to reque
 
 Interoperability snaps and account management snaps use the methods `snap_getEntropy`, `snap_getBip44Entropy`, `snap_getBip32Entropy`, and `snap_getBip32PublicKey` to generate addresses and other key material.
 
-These methods assume the client contains a single entropy source (the user's primary keyring mnemonic). The proposed API will allow snaps to request entropy from a specific source such as a secondary mnemonic.
+These methods assume the client contains a single entropy source (the user's primary keyring mnemonic). The proposed API changes will allow snaps to request entropy from a specific source such as a secondary mnemonic. A new method `snap_listAvailableEntropySources` will be added to allow snaps to request a list of available entropy sources.
 
 ## Specification
 
@@ -26,6 +26,18 @@ The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "S
 "NOT RECOMMENDED", "MAY", and "OPTIONAL" written in uppercase in this document are to be interpreted as described in
 [RFC 2119](https://www.ietf.org/rfc/rfc2119.txt)
 
+### Snap Manifest
+
+A new set permission is added to the snap manifest:
+
+```json
+{
+  "initialPermissions": {
+    "snap_listAvailableEntropySources": {}
+  }
+}
+```
+
 
 ### Common Types
 ```typescript
@@ -38,9 +50,7 @@ type Slip10Node = {
   chainCode: string;
   curve: "ed25519" | "secp256k1";
 };
-```
 
-```typescript
 export type BIP44Node = {
   coin_type: number;
   depth: number;
@@ -49,6 +59,12 @@ export type BIP44Node = {
   chainCode: string;
   path: string[];
 };
+
+interface EntropySource {
+  name: string;
+  id: string;
+  type: "mnemonic";
+}
 ```
 
 ### Scope
@@ -61,8 +77,12 @@ No changes are required to the snap manifest.
 
 ### Client wallet implementation
 
-If a snap requests entropy and includes the `source` parameter, the wallet MUST return entropy corresponding to that source, if it exists.
-If it does not exist, the wallet MUST respond with an error.
+If a snap requests a list of available entropy sources, and it has the permission to do so, the wallet MUST return a list of `EntropySource` objects.
+
+If a snap requests entropy and includes the `source` parameter for an entropy source of type `mnemonic`, the wallet MUST return entropy corresponding to that source, if it exists.
+
+If the source does not exist, the wallet MUST respond with an error.
+
 If the request does not include the `source` parameter, the wallet MUST return entropy from the default source.
 
 A client wallet MAY invoke the `keyring.createAccount` method with an `entropySource` parameter in the `options` object.
@@ -73,7 +93,23 @@ The `entropySource` parameter MUST be a string which uniquely identifies the ent
 
 If a snap is asked to create an account via `keyring.createAccount`, and the `entropySource` parameter is provided, and the snap requires entropy to create an account,the snap SHOULD request the entropy from the specified source.
 
-### RPC Methods
+### New RPC Methods
+
+#### `snap_listAvailableEntropySources`
+
+The method returns an array of `EntropySource` objects, each representing an available entropy source. It is intended that the snap will display this list to the user.
+
+```typescript
+const entropySources = await snap.request({
+  method: "snap_listAvailableEntropySources",
+});
+// [
+//   { name: "Phrase 1", id: "phrase-1" },
+//   { name: "Phrase 2", id: "phrase-2" },
+// ]
+```
+
+### Existing RPC Methods
 
 #### `snap_getEntropy`