Blockchain Traits

.gitlab-ci.yml

@@ -44,6 +44,8 @@ publish:development:
 
     # Checkout the development branch so that we're not on a detached HEAD (which GitLab CI will default to).
     - git checkout development
+    # Forcefully pull the latest changes.
+    - git pull
 
     # Setup npm config for npmjs.com
     - npm config set registry https://registry.npmjs.org/

packages/primitives/src/address.ts

@@ -226,6 +226,21 @@ export class Address {
     return this.fromRedeemScript(Bytes.fromHex(hex).toBytes(), type);
   }
 
+  /**
+   * Attempt to instantiate Address from Locking Bytecode.
+   *
+   * @param lockscript The lockscript as bytes or hex.
+   *
+   * @throws {Error} If lock script cannot be decoded into an address.
+   *
+   * @returns Instance of Address.
+   */
+  public static fromLockscript(lockscript: string | Uint8Array) {
+    return lockscript instanceof Uint8Array
+      ? this.fromLockscriptBytes(lockscript)
+      : this.fromLockscriptHex(lockscript);
+  }
+
   /**
    * Attempt to instantiate Address from Locking Bytecode.
    *

packages/stack/src/blockchain/base-blockchain.ts

@@ -1,10 +1,9 @@
 import { EventEmitter } from '../utils';
 
 import {
-  type AddressCallback,
+  type BlockchainCallback,
   type BlockchainUTXOs,
   type BlockchainTransactions,
-  type TransactionCallback,
 } from './types.js';
 
 import { type Transaction } from '@xocash/primitives';
@@ -25,7 +24,10 @@ export type BlockchainEvents = {
  * @abstract
  * @extends {EventEmitter<BlockchainEvents>}
  */
-export abstract class BaseBlockchain extends EventEmitter<BlockchainEvents> {
+export abstract class BaseBlockchain<
+  AddressNotificationPayload = undefined,
+  TransactionNotificationPayload = undefined,
+> extends EventEmitter<BlockchainEvents> {
   // TODO: Lockscript might be better as the Subscribe Handler.
   //       From this, we can convert it to address.
   //       Fulcrum has Scripthash too - but I'm hesitant about this.
@@ -40,7 +42,6 @@ export abstract class BaseBlockchain extends EventEmitter<BlockchainEvents> {
    * Initializes the blockchain connection and required resources.
    * Should be called before performing any blockchain operations.
    *
-   * @abstract
    * @returns {Promise<void>} A promise that resolves when the blockchain connection is established
    * @throws {Error} If the connection cannot be established
    */
@@ -50,35 +51,26 @@ export abstract class BaseBlockchain extends EventEmitter<BlockchainEvents> {
    * Gracefully terminates the blockchain connection and cleans up resources.
    * Should be called when blockchain operations are no longer needed.
    *
-   * @abstract
    * @returns {Promise<void>} A promise that resolves when the shutdown is complete
    */
   abstract stop(): Promise<void>;
 
+  //-----------------------------------------------------------------------
+  // Traits (refer to traits.ts for docs)
+  //-----------------------------------------------------------------------
+
   /**
    * Retrieves all unspent transaction outputs (UTXOs) for a given address.
    *
-   * @abstract
    * @param {string} address - The blockchain address to query
    * @returns {Promise<BlockchainUTXOs>} A promise that resolves with the unspent outputs
    * @throws {Error} If the address is invalid or the query fails
    */
   abstract fetchUnspents(address: string): Promise<BlockchainUTXOs>;
 
-  /**
-   * Retrieves detailed information about a specific transaction.
-   *
-   * @abstract
-   * @param {string} txHash - The transaction hash/ID to look up
-   * @returns {Promise<Transaction>} A promise that resolves with the transaction details
-   * @throws {Error} If the transaction cannot be found or the query fails
-   */
-  abstract fetchTransaction(txHash: string): Promise<Transaction>;
-
   /**
    * Retrieves all transactions associated with a specific address.
    *
-   * @abstract
    * @param {string} address - The blockchain address to query
    * @returns {Promise<BlockchainTransactions>} A promise that resolves with the list of transactions
    * @throws {Error} If the address is invalid or the query fails
@@ -87,27 +79,55 @@ export abstract class BaseBlockchain extends EventEmitter<BlockchainEvents> {
     address: string,
   ): Promise<BlockchainTransactions>;
 
-  // TODO: We may have a fetchTokenHistory in future, but Fulcrum does not currently support indexing tokens.
+  /**
-  //       There are actually a few functional discrepancies with the adapters: different adapters grant different capabilities.
+   * Retrieves detailed information about a specific transaction.
-  //       For example, Chaingraph can fetch token and address history. But BCHN P2P network cannot even fetch address history.
+   *
-  //       We might want to handle this by having multiple BlockchainInterfaces (e.g. IBlockchainAddressSubscriptions) that describe capabilities.
+   * @param {string} txHash - The transaction hash/ID to look up
-  //       But we should return to that later.
+   * @returns {Promise<Transaction>} A promise that resolves with the transaction details
+   * @throws {Error} If the transaction cannot be found or the query fails
+   */
+  abstract fetchTransaction(txHash: string): Promise<Transaction>;
 
   /**
    * Broadcasts a raw transaction to the blockchain network.
    *
-   * @abstract
    * @param {Uint8Array} transaction - The serialized transaction data to broadcast
    * @returns {Promise<void>} A promise that resolves when the transaction is successfully broadcast
    * @throws {Error} If the transaction is invalid or broadcasting fails
    */
   abstract broadcastTransaction(transaction: Uint8Array): Promise<void>;
 
+  /**
+   * Subscribes to updates for a specific lockscript.
+   * The provided callback will be invoked when relevant events occur for the address.
+   *
+   * @param lockscript - The blockchain lockscript to monitor
+   * @param callback - The callback function to handle address-related events
+   * @returns {Promise<void>} A promise that resolves when the subscription is established
+   * @throws {Error} If the subscription cannot be created
+   */
+  abstract subscribeLockscript(
+    lockscript: string | Uint8Array,
+    callback: BlockchainCallback<AddressNotificationPayload>,
+  ): Promise<void>;
+
+  /**
+   * Removes a subscription for a specific blockchain address.
+   *
+   * @param lockscript - The blockchain lockscript to unsubscribe from
+   * @param callback - The callback function to remove
+   * @returns {Promise<void>} A promise that resolves when the subscription is removed
+   * @throws {Error} If the subscription cannot be removed
+   */
+  abstract unsubscribeLockscript(
+    lockscript: string | Uint8Array,
+    callback: BlockchainCallback<AddressNotificationPayload>,
+  ): Promise<boolean>;
+
   /**
    * Subscribes to updates for a specific blockchain address.
    * The provided callback will be invoked when relevant events occur for the address.
    *
-   * @abstract
    * @param {string} address - The blockchain address to monitor
    * @param {AddressCallback} callback - The callback function to handle address-related events
    * @returns {Promise<void>} A promise that resolves when the subscription is established
@@ -115,13 +135,12 @@ export abstract class BaseBlockchain extends EventEmitter<BlockchainEvents> {
    */
   abstract subscribeAddress(
     address: string,
-    callback: AddressCallback,
+    callback: BlockchainCallback<AddressNotificationPayload>,
   ): Promise<void>;
 
   /**
    * Removes a subscription for a specific blockchain address.
    *
-   * @abstract
    * @param {string} address - The blockchain address to unsubscribe from
    * @param {AddressCallback} callback - The callback function to remove
    * @returns {Promise<void>} A promise that resolves when the subscription is removed
@@ -129,14 +148,13 @@ export abstract class BaseBlockchain extends EventEmitter<BlockchainEvents> {
    */
   abstract unsubscribeAddress(
     address: string,
-    callback: AddressCallback,
+    callback: BlockchainCallback<AddressNotificationPayload>,
-  ): Promise<void>;
+  ): Promise<boolean>;
 
   /**
    * Subscribes to updates for a specific transaction.
    * The provided callback will be invoked when relevant events occur for the transaction.
    *
-   * @abstract
    * @param {string} transactionHash - The transaction hash to monitor
    * @param {TransactionCallback} callback - The callback function to handle transaction-related events
    * @returns {Promise<void>} A promise that resolves when the subscription is established
@@ -144,13 +162,12 @@ export abstract class BaseBlockchain extends EventEmitter<BlockchainEvents> {
    */
   abstract subscribeTransaction(
     transactionHash: string,
-    callback: TransactionCallback,
+    callback: BlockchainCallback<TransactionNotificationPayload>,
   ): Promise<void>;
 
   /**
    * Removes a subscription for a specific transaction.
    *
-   * @abstract
    * @param {string} transactionHash - The transaction hash to unsubscribe from
    * @param {TransactionCallback} callback - The callback function to remove
    * @returns {Promise<void>} A promise that resolves when the subscription is removed
@@ -158,6 +175,6 @@ export abstract class BaseBlockchain extends EventEmitter<BlockchainEvents> {
    */
   abstract unsubscribeTransaction(
     transactionHash: string,
-    callback: TransactionCallback,
+    callback: BlockchainCallback<TransactionNotificationPayload>,
-  ): Promise<void>;
+  ): Promise<boolean>;
 }

packages/stack/src/blockchain/blockchain-electrum.ts

@@ -1,7 +1,6 @@
 import { BaseBlockchain } from './base-blockchain.js';
 import {
-  type AddressCallback,
+  type BlockchainCallback,
-  type TransactionCallback,
   type BlockchainTransaction,
   type BlockchainUTXO,
 } from './types.js';
@@ -53,7 +52,20 @@ export type BlockchainElectrumParams = {
   opts?: Partial<BlockchainElectrumOpts>;
 };
 
-export class BlockchainElectrum extends BaseBlockchain {
+export type AddressStatusPayload = {
+  type: 'address-status';
+  status: string | null;
+};
+
+export type BlockHeightPayload = {
+  type: 'block-height';
+  height: number | null;
+};
+
+export class BlockchainElectrum extends BaseBlockchain<
+  AddressStatusPayload,
+  BlockHeightPayload
+> {
   // Composables.
   electrumClient!: ElectrumClient<ElectrumProtocolEvents>;
 
@@ -61,9 +73,17 @@ export class BlockchainElectrum extends BaseBlockchain {
   isConnected = false;
   blockHeight: number | undefined = undefined;
 
-  // Subscriptions State.
+  // Address Subscriptions State.
-  addressSubscriptions: Map<string, Set<AddressCallback>> = new Map();
+  addressSubscriptions: Map<
-  transactionSubscriptions: Map<string, Set<TransactionCallback>> = new Map();
+    string,
+    Set<BlockchainCallback<AddressStatusPayload>>
+  > = new Map();
+
+  // Transaction Subscription State.
+  transactionSubscriptions: Map<
+    string,
+    Set<BlockchainCallback<BlockHeightPayload>>
+  > = new Map();
 
   // Options
   store: BaseStore;
@@ -314,7 +334,7 @@ export class BlockchainElectrum extends BaseBlockchain {
       }, timeoutMs);
 
       // Create a subscribe function so that we get notified when transaction is seen by network
-      const subscribeCallback = (_height: number | null) => {
+      const subscribeCallback = () => {
         clearTimeout(timeout);
         this.unsubscribeTransaction(tx.toHashHex(), subscribeCallback);
         resolve();
@@ -356,13 +376,47 @@ export class BlockchainElectrum extends BaseBlockchain {
     await waitForTxPromise;
   }
 
-  async subscribeAddress(address: string, callback: AddressCallback) {
+  async subscribeLockscript(
+    lockscript: string | Uint8Array,
+    callback: BlockchainCallback<AddressStatusPayload>,
+  ) {
+    // Fulcrum does not support subscribing to lockscripts, so we cast it to an address.
+    const address = Address.fromLockscript(lockscript);
+
+    // TODO: Refactor to work around ScriptHash for Fulcrum.
+    //       Otherwise, we may get issues with CashAddr/Legacy Addresses.
+
+    // Use our subscribeAddress function.
+    return await this.subscribeAddress(address.toCashAddr(), callback);
+  }
+
+  async unsubscribeLockscript(
+    lockscript: string | Uint8Array,
+    callback: BlockchainCallback<AddressStatusPayload>,
+  ): Promise<boolean> {
+    // Fulcrum does not support subscribing to lockscripts, so we cast it to an address.
+    const address = Address.fromLockscript(lockscript);
+
+    // TODO: Refactor to work around ScriptHash for Fulcrum.
+    //       Otherwise, we may get issues with CashAddr/Legacy Addresses.
+
+    // Use our unsubscribeAddress function.
+    return await this.unsubscribeAddress(address.toCashAddr(), callback);
+  }
+
+  async subscribeAddress(
+    address: string,
+    callback: BlockchainCallback<AddressStatusPayload>,
+  ) {
     // Wait for connection to be established before attempting to subscribe.
     // TODO: Consider doing this at a higher level.
     if (!this.isConnected) {
       await this.waitFor('isConnectedUpdated', (isConnected) => isConnected);
     }
 
+    // TODO: Refactor to work around ScriptHash for Fulcrum.
+    //       Otherwise, we may get issues with CashAddr/Legacy Addresses.
+
     // Get or create the set of callbacks for this transaction
     let callbacks = this.addressSubscriptions.get(address);
     if (!callbacks) {
@@ -379,17 +433,28 @@ export class BlockchainElectrum extends BaseBlockchain {
     callbacks.add(callback);
   }
 
-  async unsubscribeAddress(address: string, callback: AddressCallback) {
+  async unsubscribeAddress(
+    address: string,
+    callback: BlockchainCallback<AddressStatusPayload>,
+  ) {
     // Wait for connection to be established before attempting to subscribe.
     // TODO: Consider doing this at a higher level.
     if (!this.isConnected) {
       await this.waitFor('isConnectedUpdated', (isConnected) => isConnected);
     }
 
+    // TODO: Refactor to work around ScriptHash for Fulcrum.
+    //       Otherwise, we may get issues with CashAddr/Legacy Addresses.
+
     // Get the callbacks set for this address
     const callbacks = this.addressSubscriptions.get(address);
     if (!callbacks) {
-      return;
+      return false;
+    }
+
+    // Find the index of the callback in the handlers array
+    if (!callbacks.has(callback)) {
+      return false;
     }
 
     // Remove the specific callback
@@ -405,11 +470,13 @@ export class BlockchainElectrum extends BaseBlockchain {
         address,
       );
     }
+
+    return true;
   }
 
   async subscribeTransaction(
     transactionHash: string,
-    callback: TransactionCallback,
+    callback: BlockchainCallback<BlockHeightPayload>,
   ) {
     // Wait for connection to be established before attempting to subscribe.
     // TODO: Consider doing this at a higher level.
@@ -435,7 +502,7 @@ export class BlockchainElectrum extends BaseBlockchain {
 
   async unsubscribeTransaction(
     transactionHash: string,
-    callback: TransactionCallback,
+    callback: BlockchainCallback<BlockHeightPayload>,
   ) {
     // Wait for connection to be established before attempting to subscribe.
     // TODO: Consider doing this at a higher level.
@@ -446,7 +513,11 @@ export class BlockchainElectrum extends BaseBlockchain {
     // Get the callbacks set for this transaction
     const callbacks = this.transactionSubscriptions.get(transactionHash);
     if (!callbacks) {
-      return;
+      return false;
+    }
+
+    if (!callbacks.has(callback)) {
+      return false;
     }
 
     // Remove the specific callback
@@ -462,6 +533,8 @@ export class BlockchainElectrum extends BaseBlockchain {
         transactionHash,
       );
     }
+
+    return true;
   }
 
   async request(method: string, ...parameters: Array<RPCParameter>) {
@@ -523,7 +596,7 @@ export class BlockchainElectrum extends BaseBlockchain {
     // Execute all callbacks for this transaction.
     for (const callback of callbacks) {
       try {
-        callback(status);
+        callback(address, { type: 'address-status', status });
       } catch (error) {
         // Handle or log any callback execution errors
         console.error(
@@ -549,7 +622,7 @@ export class BlockchainElectrum extends BaseBlockchain {
     // Execute all callbacks for this transaction.
     for (const callback of callbacks) {
       try {
-        callback(height);
+        callback(txHash, { type: 'block-height', height });
       } catch (error) {
         // Handle or log any callback execution errors
         console.error(

packages/stack/src/blockchain/blockchain-inmemory.ts

@@ -1,7 +1,6 @@
 import { BaseBlockchain } from './base-blockchain.js';
 import {
-  type AddressCallback,
+  type BlockchainCallback,
-  type TransactionCallback,
   type BlockchainTransaction,
   type BlockchainTransactions,
   type BlockchainUTXO,
@@ -24,10 +23,14 @@ import {
 
 // Local Blockchain Adapter.
 // This simulates the BCH Blockchain.
-export class BlockchainLocal extends BaseBlockchain {
+export class BlockchainInMemory extends BaseBlockchain {
+  static from() {
+    return new BlockchainInMemory();
+  }
+
   private transactions: BlockchainTransactions;
-  private addressSubscriptions: Map<string, Set<AddressCallback>>;
+  private addressSubscriptions: Map<string, Set<BlockchainCallback>>;
-  private transactionSubscriptions: Map<string, Set<TransactionCallback>>;
+  private transactionSubscriptions: Map<string, Set<BlockchainCallback>>;
 
   constructor() {
     super();
@@ -37,13 +40,9 @@ export class BlockchainLocal extends BaseBlockchain {
     this.transactionSubscriptions = new Map();
   }
 
-  async start() {
+  async start() {}
-    console.log('BlockchainLocal: Started');
-  }
 
-  async stop() {
+  async stop() {}
-    console.log('BlockchainLocal: Stopped');
-  }
 
   async fetchUnspents(address: string) {
     // Derive the current UTXO set.
@@ -117,7 +116,7 @@ export class BlockchainLocal extends BaseBlockchain {
       });
 
       // Validate the transaction.
-      BlockchainLocal.validateTransaction(
+      BlockchainInMemory.validateTransaction(
         tx,
         sourceOutputs.map((utxo) => utxo.output),
       );
@@ -135,7 +134,35 @@ export class BlockchainLocal extends BaseBlockchain {
     this.notifyTransactionSubscribers(tx);
   }
 
-  async subscribeAddress(address: string, callback: AddressCallback) {
+  async subscribeLockscript(
+    lockscript: string | Uint8Array,
+    callback: BlockchainCallback,
+  ) {
+    // Fulcrum does not support subscribing to lockscripts, so we cast it to an address.
+    const address = Address.fromLockscript(lockscript);
+
+    // TODO: Refactor to work around ScriptHash for Fulcrum.
+    //       Otherwise, we may get issues with CashAddr/Legacy Addresses.
+
+    // Use our subscribeAddress function.
+    return await this.subscribeAddress(address.toCashAddr(), callback);
+  }
+
+  async unsubscribeLockscript(
+    lockscript: string | Uint8Array,
+    callback: BlockchainCallback,
+  ): Promise<boolean> {
+    // Fulcrum does not support subscribing to lockscripts, so we cast it to an address.
+    const address = Address.fromLockscript(lockscript);
+
+    // TODO: Refactor to work around ScriptHash for Fulcrum.
+    //       Otherwise, we may get issues with CashAddr/Legacy Addresses.
+
+    // Use our unsubscribeAddress function.
+    return await this.unsubscribeAddress(address.toCashAddr(), callback);
+  }
+
+  async subscribeAddress(address: string, callback: BlockchainCallback) {
     // Convert the address to it's lockscript hex so that it's consistently represented.
     const lockscriptHex = Address.from(address).toLockscriptHex();
 
@@ -145,26 +172,35 @@ export class BlockchainLocal extends BaseBlockchain {
     }
 
     // Add the address notification callback.
-    this.addressSubscriptions.get(address)!.add(callback);
+    this.addressSubscriptions.get(lockscriptHex)!.add(callback);
   }
 
-  async unsubscribeAddress(address: string, callback: AddressCallback) {
+  async unsubscribeAddress(address: string, callback: BlockchainCallback) {
     // Convert the address to it's lockscript hex so that it's consistently represented.
     const lockscriptHex = Address.from(address).toLockscriptHex();
 
     // Find all callbacks this lockscript is subscribed to.
     const callbacks = this.addressSubscriptions.get(lockscriptHex);
     if (callbacks) {
+      if (callbacks.has(callback)) {
+        return false;
+      }
+
       callbacks.delete(callback);
+
       if (callbacks.size === 0) {
         this.addressSubscriptions.delete(address);
       }
+
+      return true;
     }
+
+    return false;
   }
 
   async subscribeTransaction(
     transactionHash: string,
-    callback: TransactionCallback,
+    callback: BlockchainCallback,
   ) {
     if (!this.transactionSubscriptions.has(transactionHash)) {
       this.transactionSubscriptions.set(transactionHash, new Set());
@@ -174,15 +210,21 @@ export class BlockchainLocal extends BaseBlockchain {
 
   async unsubscribeTransaction(
     transactionHash: string,
-    callback: TransactionCallback,
+    callback: BlockchainCallback,
   ) {
     const callbacks = this.transactionSubscriptions.get(transactionHash);
     if (callbacks) {
+      if (!callbacks.has(callback)) {
+        return false;
+      }
+
       callbacks.delete(callback);
       if (callbacks.size === 0) {
         this.transactionSubscriptions.delete(transactionHash);
       }
     }
+
+    return false;
   }
 
   private notifyAddressSubscribers(tx: Transaction) {
@@ -208,7 +250,7 @@ export class BlockchainLocal extends BaseBlockchain {
       const callbacks = this.addressSubscriptions.get(address);
 
       if (callbacks) {
-        callbacks.forEach((callback) => callback('updated'));
+        callbacks.forEach((callback) => callback(address));
       }
     });
 
@@ -221,7 +263,7 @@ export class BlockchainLocal extends BaseBlockchain {
       const callbacks = this.addressSubscriptions.get(address);
 
       if (callbacks) {
-        callbacks.forEach((callback) => callback('updated'));
+        callbacks.forEach((callback) => callback(address));
       }
     });
   }
@@ -231,7 +273,7 @@ export class BlockchainLocal extends BaseBlockchain {
     const callbacks = this.transactionSubscriptions.get(txHash);
     if (callbacks) {
       // In this local simulation, we're not tracking block height, so we'll use null
-      callbacks.forEach((callback) => callback(null));
+      callbacks.forEach((callback) => callback(txHash));
     }
   }
 
@@ -274,6 +316,26 @@ export class BlockchainLocal extends BaseBlockchain {
     return utxoMap;
   }
 
+  async mineBlock(outputs: Array<Output>): Promise<void> {
+    // Create a transaction that pays to our subscribed address.
+    const transaction = Transaction.fromRaw({
+      version: 2,
+      locktime: 0,
+      inputs: [
+        {
+          outpointIndex: 0,
+          outpointTransactionHash: new Uint8Array(),
+          unlockingBytecode: new Uint8Array(),
+          sequenceNumber: 0,
+        },
+      ],
+      outputs,
+    });
+
+    // Broadcast that transaction.
+    await this.broadcastTransaction(transaction, { skipValidation: true });
+  }
+
   /**
    * @remarks Consider moving this to Transaction Primitive. Trade-off is that it's probably big. Maybe standalone util?
    */

packages/stack/src/blockchain/blockchain.ts

@@ -1,100 +0,0 @@
-import { BaseBlockchain } from './base-blockchain.js';
-import { type AddressCallback, type TransactionCallback } from './types.js';
-import { BlockchainElectrum } from './blockchain-electrum.js';
-import { BlockchainLocal } from './blockchain-local.js';
-
-import { Transaction } from '@xocash/primitives';
-
-/**
- * The idea here is that this will implement the IBlockchain interface.
- * But, it will allow the dev to specify multiple child IBlockchain interfaces for configuration.
- * So, if the network is not available, it can fallback to the local and sync later.
- *
- * @example
- * ```ts
- * // Actual interface will be more complex, but this is the rough idea.
- * const blockchain = new Blockchain([
- *   new BlockchainLocal(...),
- *   new BlockchainElectrum(...)
- * ])
- * ```
- */
-export class Blockchain extends BaseBlockchain {
-  blockchainLocal: BlockchainLocal;
-  blockchainElectrum: BlockchainElectrum;
-
-  constructor() {
-    super();
-
-    this.blockchainLocal = new BlockchainLocal();
-    this.blockchainElectrum = new BlockchainElectrum();
-  }
-
-  async start() {
-    await Promise.all([
-      this.blockchainLocal.start(),
-      this.blockchainElectrum.start(),
-    ]);
-  }
-
-  async stop() {
-    await Promise.all([
-      this.blockchainLocal.stop(),
-      this.blockchainElectrum.stop(),
-    ]);
-  }
-
-  async fetchUnspents(address: string) {
-    if (this.blockchainElectrum.isConnected) {
-      return await this.blockchainElectrum.fetchUnspents(address);
-    } else {
-      return await this.blockchainLocal.fetchUnspents(address);
-    }
-  }
-
-  async fetchTransaction(txHash: string) {
-    if (this.blockchainElectrum.isConnected) {
-      return await this.blockchainElectrum.fetchTransaction(txHash);
-    } else {
-      return await this.blockchainLocal.fetchTransaction(txHash);
-    }
-  }
-
-  async fetchAddressHistory(address: string) {
-    if (this.blockchainElectrum.isConnected) {
-      return await this.blockchainElectrum.fetchAddressHistory(address);
-    } else {
-      return await this.blockchainLocal.fetchAddressHistory(address);
-    }
-  }
-
-  async broadcastTransaction(tx: Uint8Array | Transaction | string) {
-    if (this.blockchainElectrum.isConnected) {
-      return await this.blockchainElectrum.broadcastTransaction(tx);
-    } else {
-      return await this.blockchainLocal.broadcastTransaction(tx);
-    }
-  }
-
-  async subscribeAddress(_address: string, _callback: AddressCallback) {
-    throw new Error('Not yet implemented');
-  }
-
-  async unsubscribeAddress(_address: string, _callback: AddressCallback) {
-    throw new Error('Not yet implemented');
-  }
-
-  async subscribeTransaction(
-    _transactionHash: string,
-    _callback: TransactionCallback,
-  ) {
-    throw new Error('Not yet implemented');
-  }
-
-  async unsubscribeTransaction(
-    _transactionHash: string,
-    _callback: TransactionCallback,
-  ) {
-    throw new Error('Not yet implemented');
-  }
-}

packages/stack/src/blockchain/index.ts

@@ -1,5 +1,5 @@
 export * from './base-blockchain.js';
-export * from './blockchain.js';
 export * from './blockchain-electrum.js';
-export * from './blockchain-local.js';
+export * from './blockchain-inmemory.js';
+export * from './traits.js';
 export * from './types.js';

packages/stack/src/blockchain/traits.ts

@@ -0,0 +1,24 @@
+import { type BaseBlockchain } from './base-blockchain.js';
+
+export type BlockchainLockscriptSubscribable<CallbackPayload = undefined> =
+  Pick<
+    BaseBlockchain<CallbackPayload>,
+    'subscribeLockscript' | 'unsubscribeLockscript'
+  >;
+
+export type BlockchainAddressSubscribable<CallbackPayload = undefined> = Pick<
+  BaseBlockchain<CallbackPayload>,
+  'subscribeAddress' | 'unsubscribeAddress'
+>;
+
+export type BlockchainTransactionSubscribable<CallbackPayload = undefined> =
+  Pick<
+    BaseBlockchain<CallbackPayload>,
+    'subscribeTransaction' | 'unsubscribeTransaction'
+  >;
+
+// TODO: We may have a fetchTokenHistory in future, but Fulcrum does not currently support indexing tokens.
+//       There are actually a few functional discrepancies with the adapters: different adapters grant different capabilities.
+//       For example, Chaingraph can fetch token and address history. But BCHN P2P network cannot even fetch address history.
+//       We might want to handle this by having multiple BlockchainInterfaces (e.g. IBlockchainAddressSubscriptions) that describe capabilities.
+//       But we should return to that later.

packages/stack/src/blockchain/types.ts

@@ -1,7 +1,11 @@
 import { Transaction, TransactionHash, UTXO, ExtMap } from '@xocash/primitives';
 
-export type AddressCallback = (status: string | null) => void;
+export type BlockchainCallback<Payload = undefined> = (
-export type TransactionCallback = (height: number | null) => void;
+  /** The transaction hash, address, lockscript or scriptHash of this subscription. */
+  id: string,
+  /** Additional payload information provided by this subscription */
+  payload?: Payload | undefined,
+) => void;
 
 export type BlockchainTransaction = {
   hash: TransactionHash;

packages/stack/src/wallet/base-wallet.ts

@@ -5,10 +5,7 @@ import {
   type WalletTransactions,
 } from './types.js';
 
-import {
+import { type BlockchainUTXOs } from '../blockchain';
-  type BlockchainTransactions,
-  type BlockchainUTXOs,
-} from '../blockchain';
 import { type Activities } from '../storage';
 import { EventEmitter } from '../utils';
 
@@ -16,7 +13,7 @@ import { type TokenBalances, type Address } from '@xocash/primitives';
 
 export type WalletEvents = {
   shouldMonitorUpdated: boolean;
-  transactionsUpdated: BlockchainTransactions;
+  transactionsUpdated: WalletTransactions;
   unspentsUpdated: BlockchainUTXOs;
   stateUpdated: string | null;
 };

packages/stack/src/wallet/types.ts

@@ -1,4 +1,9 @@
-import { type BaseBlockchain, type BlockchainTransaction } from '../blockchain';
+import {
+  type BaseBlockchain,
+  type AddressStatusPayload,
+  type BlockHeightPayload,
+  type BlockchainTransaction,
+} from '../blockchain';
 import { type Activities, type BaseStore } from '../storage';
 
 import { type Address, type ExtMap } from '@xocash/primitives';
@@ -12,9 +17,15 @@ import {
   type Output,
 } from '@bitauth/libauth';
 
+// NOTE: For Wallets, the Blockchain Adapter must have Address and Transaction indexing.
+export type WalletBlockchain = BaseBlockchain<
+  AddressStatusPayload,
+  BlockHeightPayload
+>;
+
 export type WalletDependencies = {
   activities?: Activities;
-  blockchain: BaseBlockchain;
+  blockchain: WalletBlockchain;
   cache?: BaseStore;
 };
 
@@ -24,7 +35,6 @@ export type InputTemplateBCH = InputTemplate<
   CompilationData
 >;
 
-// TODO: Rename me to WalletUTXO
 export type WalletUTXO = {
   outpointIndex: number;
   outpointTransactionHash: Uint8Array;

packages/stack/src/wallet/wallet-hd.ts

@@ -1,10 +1,9 @@
 import { BaseWallet } from './base-wallet.js';
 import { type TransactionTemplate } from './types.js';
 import { TransactionBuilder } from './transaction-builder.js';
-import { type WalletDependencies } from './types.js';
+import { type WalletBlockchain, type WalletDependencies } from './types.js';
 import { WalletP2PKH } from './wallet-p2pkh.js';
 
-import { type BaseBlockchain } from '../blockchain';
 import { type BaseStore, Activities, StoreInMemory } from '../storage';
 
 import {
@@ -80,7 +79,7 @@ export class WalletHD extends BaseWallet {
 
   // Dependencies.
   public readonly activities: Activities;
-  public readonly blockchain: BaseBlockchain;
+  public readonly blockchain: WalletBlockchain;
   public readonly cache: BaseStore;
 
   // Genesis Data.

packages/stack/src/wallet/wallet-p2pkh.ts

@@ -1,8 +1,15 @@
 import { BaseWallet } from './base-wallet.js';
-import { type TransactionTemplate, type WalletDependencies } from './types.js';
+import {
+  type TransactionTemplate,
+  type WalletBlockchain,
+  type WalletDependencies,
+} from './types.js';
 import { TransactionBuilder } from './transaction-builder.js';
 
-import { type BaseBlockchain, type BlockchainTransaction } from '../blockchain';
+import {
+  type AddressStatusPayload,
+  type BlockchainTransaction,
+} from '../blockchain';
 import { type BaseStore, Activities, StoreInMemory } from '../storage';
 
 import {
@@ -116,7 +123,7 @@ export class WalletP2PKH extends BaseWallet {
 
   // Dependencies.
   public readonly activities: Activities;
-  public readonly blockchain: BaseBlockchain;
+  public readonly blockchain: WalletBlockchain;
   public readonly cache: BaseStore;
 
   // Genesis Data.
@@ -408,11 +415,14 @@ export class WalletP2PKH extends BaseWallet {
     await this.blockchain.broadcastTransaction(generatedTxBytes);
   }
 
-  private async onAddressNotification(status: string | null) {
+  private async onAddressNotification(
+    _address: string,
+    payload?: AddressStatusPayload,
+  ) {
     // If wallet state has changed...
-    if (status !== this.status) {
+    if (payload && payload.status !== this.status) {
       // Set our new status.
-      this.status = status;
+      this.status = payload.status;
 
       // Emit an event.
       this.emit('stateUpdated', this.status);