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+- Feature Name: wallet-lib-shared-facades
+- Start Date: 2026-01-21
+- RFC PR: (leave this empty)
+- Hathor Issue: (leave this empty)
+- Author: tulio@hathor.network
+
+# Summary
+[summary]: #summary
+
+The Wallet Lib facades for the Fullnode and the Wallet Service should share a
+subset of the most important methods, with the same parameters and output data
+format.
+
+This will cause breaking changes that will require a major version update
+on the lib.
+
+# Motivation
+[motivation]: #motivation
+
+Why are we doing this? What use cases does it support? What is the expected
+outcome?
+
+At the moment, both facades are similar, but not equal. This causes duplicated
+test suites, requires additional time and attention from the developers and
+ultimately introduces bugs on the Wallet Lib clients when they need to switch
+between facades.
+
+# Guide-level explanation
+[guide-level-explanation]: #guide-level-explanation
+
+To achieve this state it's necessary to change the contracts for some methods,
+both in the wallets and in their shared interface `IHathorWallet`, which is now
+outdated. An [initial investigation](./shared-contract-investigation.md) was made
+to understand the necessary changes, and they will be summarized below.
+
+- Change methods from `sync` to `async` on the Wallet Service facade
+- Modify `IHathorWallet` return types that currently do not match the fullnode facade
+- Create types for the parameters of both facades, facilitating visual inspection from devs
+- Decide on `UTXO` and `Tx History` objects that currently differ, and are used by most of the applications
+- Decide which subset of methods will consist of the `IHathorWallet`, and leave each facade to have its own complementary methods
+- Add methods that are present in both facades but not in the `IHathorWallet`, such as `getAuthorityUtxo()`
+- Create a `shared_types.ts` on the root folder, instead of using types from each facade folder
+
+At the end of this project, it should be possible for a hypothetical client
+implementation to call methods from a Fullnode or Wallet Service facades
+interchangeably during its operation, with no adaptation to their inner workings.
+
+# Reference-level explanation
+[reference-level-explanation]: #reference-level-explanation
+
+This is the technical portion of the RFC. Explain the design in sufficient
+detail that:
+
+- Its interaction with other features is clear.
+- It is reasonably clear how the feature would be implemented.
+- Corner cases are dissected by example.
+
+The section should return to the examples given in the previous section, and
+explain more fully how the detailed proposal makes those examples work.
+
+# Drawbacks
+[drawbacks]: #drawbacks
+
+The only reasons not to do this would be to preserve backwards compatibility with
+existing clients, or to dedicate development priority elsewhere.
+
+# Rationale and alternatives
+[rationale-and-alternatives]: #rationale-and-alternatives
+
+The facades could be kept separate and a wrapper `WalletWrapper` could be
+developed to abstract away their differences. This would allow for shared
+integration tests and a simpler developer experience, while the internal work
+is postponed for a better time.
+
+The downside of this alternative is having additional work and complexity in
+order to avoid a synchronization work that will have to be done eventually.
+
+By not implementing this shared facade, we keep the responsibility on the client
+to know what facade is being used and the details of each one separately in the
+client code.
+
+# Prior art
+[prior-art]: #prior-art
+
+The objetive of the `IHathorWallet` interface was to create a shared contract for
+both facades, but without automated testing it was natural to drift away from
+a compliance strict enough for a full Typescript validation.
+
+The main proposal of this RFC is to bring this interface up-to-date with the
+current state of the wallets, improving it albeit with breaking changes.
+
+# Unresolved questions
+[unresolved-questions]: #unresolved-questions
+
+The main questions to resolve through this RFC are the actual method signatures,
+deciding which properties are mandatory, which will be optional.
+
+A special attention should be paid to the `null` parameter, which is used in
+many places as a valid replace for `undefined`. This is
+
+We should consider keeping a `v2` version with minor and patch updates for
+critical issues, but going forward we would fully migrate to `v3`.
+
+- What parts of the design do you expect to resolve through the RFC process
+  before this gets merged?
+- What parts of the design do you expect to resolve through the implementation
+  of this feature before stabilization?
+- What related issues do you consider out of scope for this RFC that could be
+  addressed in the future independently of the solution that comes out of this
+  RFC?
+
+# Future possibilities
+[future-possibilities]: #future-possibilities
+
+Think about breaking the facade files into multiple pieces with common
+group responsabilities, that could be shared between the two facades. This would
+make it easier for LLMs to interact with those files, instead of having
+two facades with over 3k lines that do not fit their context windows.
+
+Think about what the natural extension and evolution of your proposal would be
+and how it would affect the network and project as a whole in a holistic way.
+Try to use this section as a tool to more fully consider all possible
+interactions with the project and network in your proposal. Also consider how
+this all fits into the roadmap for the project and of the relevant sub-team.
+
+This is also a good place to "dump ideas", if they are out of scope for the
+RFC you are writing but otherwise related.
+
+If you have tried and cannot think of any future possibilities,
+you may simply state that you cannot think of anything.
+
+Note that having something written down in the future-possibilities section
+is not a reason to accept the current or a future RFC; such notes should be
+in the section on motivation or rationale in this or subsequent RFCs.
+The section merely provides additional information.
diff --git a/projects/hathor-wallet-lib/0001-shared-facades/shared-contract-investigation.md b/projects/hathor-wallet-lib/0001-shared-facades/shared-contract-investigation.md
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+# Shared Contract Investigation Report
+
+## Executive Summary
+
+This report analyzes the differences between `HathorWallet` (fullnode facade), `HathorWalletServiceWallet` (wallet service facade), and the `IHathorWallet` interface to identify contract misalignments that need resolution for unified testing.
+
+**Key Findings:**
+- 3 methods have inconsistent async/sync signatures (critical)
+- 4 methods throw "Not implemented" in WalletServiceWallet
+- ~20 methods exist only in HathorWallet
+- Return types differ significantly for several shared methods
+- The `IHathorWallet` interface has incomplete type annotations
+
+---
+
+## Part 1: Critical Contract Violations
+
+### 1.1 Async/Sync Signature Mismatches
+
+These methods have different async behaviors between facades:
+
+| Method | HathorWallet | WalletServiceWallet | IHathorWallet | Impact |
+|--------|-------------|---------------------|---------------|--------|
+| `getCurrentAddress()` | `async` → `Promise<GetCurrentAddressFullnodeFacadeReturnType>` | `sync` → `AddressInfoObject` | `AddressInfoObject \| Promise<unknown>` (FIXME) | **CRITICAL** |
+| `getNextAddress()` | `async` → `Promise<GetCurrentAddressFullnodeFacadeReturnType>` | `sync` → `AddressInfoObject` | `AddressInfoObject \| Promise<unknown>` (FIXME) | **CRITICAL** |
+| `getFullHistory()` | `async` → `Promise<Record<string, IHistoryTx>>` | `sync` (throws "Not implemented") | `TransactionFullObject[] \| Promise<unknown>` (FIXME) | **CRITICAL** |
+| `stop()` | `async` → `Promise<void>` | `async` → `Promise<void>` | `sync` → `void` | **MEDIUM** |
+
+**Impact:** Tests cannot use a simple `await` pattern because the WalletServiceWallet returns sync values.
+
+**Current Workaround (from shared tests):**
+```typescript
+// Wrapping with Promise.resolve() handles both cases
+const address = await Promise.resolve(wallet.getCurrentAddress());
+```
+
+### 1.2 Return Type Mismatches
+
+| Method | HathorWallet Return | WalletServiceWallet Return | Interface Declares |
+|--------|--------------------|-----------------------------|-------------------|
+| `getCurrentAddress()` | `{ address, index, addressPath }` | `{ address, index, addressPath, info? }` | Mixed |
+| `getMintAuthority()` | `IUtxo[]` | `AuthorityTxOutput[]` | **NOT DEFINED** |
+| `getMeltAuthority()` | `IUtxo[]` | `AuthorityTxOutput[]` | **NOT DEFINED** |
+| `getAuthorityUtxo()` | `IUtxo[]` | `AuthorityTxOutput[]` | **NOT DEFINED** |
+| `sendManyOutputsTransaction()` | `Transaction \| null` | `Transaction` | `Transaction` |
+| `sendTransaction()` | `Transaction \| null` | `Transaction` | `Transaction` |
+| `getFullHistory()` | `Record<string, IHistoryTx>` | N/A (throws) | `TransactionFullObject[]` |
+| `getAddressPrivKey()` | `Promise<unknown>` | `Promise<bitcore.HDPrivateKey>` | `Promise<bitcore.PrivateKey>` |
+
+#### 1.2.1 Detailed Type Property Comparison
+
+**Address Return Types:**
+
+| Property | `GetCurrentAddressFullnodeFacadeReturnType` (HathorWallet) | `AddressInfoObject` (WalletServiceWallet) |
+|----------|-----------------------------------------------------------|-------------------------------------------|
+| `address` | `string` | `string` |
+| `index` | `number \| null` | `number` |
+| `addressPath` | `string` | `string` |
+| `info` | ❌ Not present | `string \| undefined` (optional) |
+
+**Authority UTXO Return Types:**
+
+| Property | `IUtxo` (HathorWallet) | `AuthorityTxOutput` (WalletServiceWallet) |
+|----------|------------------------|-------------------------------------------|
+| `txId` | ✅ `string` | ✅ `string` |
+| `index` | ✅ `number` | ✅ `number` |
+| `address` | ✅ `string` | ✅ `string` |
+| `authorities` | ✅ `OutputValueType` | ✅ `OutputValueType` |
+| `token` | ✅ `string` | ❌ Not present |
+| `value` | ✅ `OutputValueType` | ❌ Not present |
+| `timelock` | ✅ `number \| null` | ❌ Not present |
+| `type` | ✅ `number` (tx version byte) | ❌ Not present |
+| `height` | ✅ `number \| null` (block outputs) | ❌ Not present |
+
+**History Return Types:**
+
+| Property | `IHistoryTx` (HathorWallet) | `TransactionFullObject` (Interface declares) |
+|----------|-----------------------------|--------------------------------------------|
+| `tx_id` | ✅ `string` | ✅ `string` |
+| `version` | ✅ `number` | ✅ `number` |
+| `timestamp` | ✅ `number` | ✅ `number` |
+| `is_voided` | ✅ `boolean` | ✅ `boolean` |
+| `inputs` | ✅ `IHistoryInput[]` | ✅ `Input[]` |
+| `outputs` | ✅ `IHistoryOutput[]` | ✅ `Output[]` |
+| `parents` | ✅ `string[]` | ✅ `string[]` |
+| `weight` | ✅ `number` | ❌ Not present |
+| `signalBits` | ✅ `number` (optional) | ❌ Not present |
+| `nonce` | ✅ `number` (optional) | ❌ Not present |
+| `token_name` | ✅ `string` (optional, create token) | ❌ Not present |
+| `token_symbol` | ✅ `string` (optional, create token) | ❌ Not present |
+| `token_version` | ✅ `TokenVersion` (optional) | ❌ Not present |
+| `tokens` | ✅ `string[]` (optional) | ❌ Not present |
+| `height` | ✅ `number` (optional) | ❌ Not present |
+| `processingStatus` | ✅ `TxHistoryProcessingStatus` (optional) | ❌ Not present |
+| `nc_id` | ✅ `string` (optional, nano contract) | ❌ Not present |
+| `nc_blueprint_id` | ✅ `string` (optional, nano contract) | ❌ Not present |
+| `nc_method` | ✅ `string` (optional, nano contract) | ❌ Not present |
+| `nc_args` | ✅ `string` (optional, nano contract) | ❌ Not present |
+
+**Note:** HathorWallet's `getFullHistory()` returns `Record<string, IHistoryTx>` (keyed by tx_id), not an array. The interface declares `TransactionFullObject[]` which is neither format.
+
+---
+
+## Part 2: Methods Not Implemented
+
+### 2.1 WalletServiceWallet "Not Implemented" Methods
+
+These methods exist but throw `WalletError('Not implemented.')`:
+
+| Method | Parameters | HathorWallet Has | Notes |
+|--------|------------|------------------|-------|
+| `getTx()` | `id: string` | ✅ Yes | Returns `IHistoryTx \| null` |
+| `getAddressInfo()` | `address: string, options?: {}` | ✅ Yes | Returns address analytics |
+| `consolidateUtxos()` | `destinationAddress: string, options?: {}` | ✅ Yes | UTXO consolidation |
+| `getFullHistory()` | None | ✅ Yes | Full tx history |
+
+### 2.2 Methods Missing from WalletServiceWallet
+
+These methods exist in HathorWallet but not in WalletServiceWallet:
+
+**Transaction Template Methods:**
+- `buildTxTemplate()`
+- `runTxTemplate()`
+
+**On-Chain Blueprint Methods:**
+- `createOnChainBlueprintTransaction()`
+- `createAndSendOnChainBlueprintTransaction()`
+
+**Nano Contract Token Methods:**
+- `createNanoContractMintTokensTransaction()` (if exists)
+- `createNanoContractMeltTokensTransaction()` (if exists)
+
+**UTXO & Address Methods:**
+- `getAvailableUtxos()` (generator)
+- `prepareConsolidateUtxosData()`
+- `consolidateUtxosSendTransaction()`
+- `getAuthorityUtxos()`
+
+**Multisig Methods:**
+- `getAllSignatures()`
+- `assemblePartialTransaction()`
+- `getMultisigData()`
+
+**Configuration Methods:**
+- `setGapLimit()`
+- `getGapLimit()`
+- `indexLimitLoadMore()`
+- `indexLimitSetEndIndex()`
+- `setExternalTxSigningMethod()`
+- `setHistorySyncMode()`
+
+**Internal/Lifecycle Methods:**
+- `syncHistory()`
+- `reloadStorage()`
+- `scanAddressesToLoad()`
+- `processTxQueue()`
+- `onEnterStateProcessing()`
+- `handleWebsocketMsg()`
+- `enqueueOnNewTx()`
+- `onNewTx()`
+
+---
+
+## Part 3: Methods Missing from IHathorWallet Interface
+
+The following methods exist in BOTH facades but are NOT in the interface:
+
+| Method | HathorWallet | WalletServiceWallet | Should Add to Interface? |
+|--------|-------------|---------------------|--------------------------|
+| `getMintAuthority()` | ✅ | ✅ | **YES** |
+| `getMeltAuthority()` | ✅ | ✅ | **YES** |
+| `getAuthorityUtxo()` | ✅ | ✅ | **YES** |
+| `markUtxoSelected()` | ✅ | ✅ (no-op) | Consider |
+| `handleSendPreparedTransaction()` | ✅ | ✅ | Consider |
+| `isReady()` | ✅ | ✅ | **YES** |
+| `getTokenData()` | ✅ | ❌ | No |
+| `clearSensitiveData()` | ✅ | ✅ | Consider |
+| `isHardwareWallet()` | ✅ | ✅ | Consider |
+| `setState()` | ✅ | ✅ | No (internal) |
+
+---
+
+## Part 4: Interface Type Issues
+
+### 4.1 Missing Return Types in IHathorWallet
+
+```typescript
+// These methods lack proper return type annotations:
+getNetworkObject();  // Return type missing
+getPrivateKeyFromAddress(address: string, options: { pinCode?: string });  // Return type missing
+```
+
+### 4.2 Loose `any`/`options` Types
+
+Many methods use untyped `options` parameter:
+```typescript
+prepareCreateNewToken(name: string, symbol: string, amount: OutputValueType, options): Promise<CreateTokenTransaction>;
+createNewToken(name: string, symbol: string, amount: OutputValueType, options): Promise<Transaction>;
+createNFT(name: string, symbol: string, amount: OutputValueType, data: string, options): Promise<Transaction>;
+prepareMintTokensData(token: string, amount: OutputValueType, options): Promise<Transaction>;
+mintTokens(token: string, amount: OutputValueType, options): Promise<Transaction>;
+prepareMeltTokensData(token: string, amount: OutputValueType, options): Promise<Transaction>;
+meltTokens(token: string, amount: OutputValueType, options): Promise<Transaction>;
+getTxBalance(tx: IHistoryTx, optionsParams): Promise<{ [tokenId: string]: OutputValueType }>;
+```
+
+### 4.3 FIXME Comments in Interface
+
+The interface has explicit FIXME comments acknowledging inconsistencies:
+```typescript
+getCurrentAddress(options?: { markAsUsed: boolean }): AddressInfoObject | Promise<unknown>; // FIXME: Should have a single return type
+getNextAddress(): AddressInfoObject | Promise<unknown>; // FIXME: Should have a single return type;
+getFullHistory(): TransactionFullObject[] | Promise<unknown>; // FIXME: Should have a single return type;
+```
+
+---
+
+## Part 5: Options Parameter Differences
+
+### 5.1 `sendTransaction()` Options
+
+| Option | HathorWallet | WalletServiceWallet | Interface |
+|--------|-------------|---------------------|-----------|
+| `token` | ✅ | ✅ | ✅ |
+| `changeAddress` | ✅ (`null` allowed) | ✅ | ✅ |
+| `pinCode` | ✅ (`null` allowed) | ✅ | ❌ Missing |
+
+### 5.2 `sendManyOutputsTransaction()` Options
+
+| Option | HathorWallet | WalletServiceWallet | Interface |
+|--------|-------------|---------------------|-----------|
+| `inputs` | ✅ | ✅ | ✅ |
+| `changeAddress` | ✅ (`null` allowed) | ✅ | ✅ |
+| `pinCode` | ✅ (`null` allowed) | ✅ | ❌ Missing |
+| `startMiningTx` | ✅ | ❌ | ❌ |
+
+### 5.3 Token Creation Options
+
+HathorWallet uses `CreateTokenOptions`:
+- `address`, `changeAddress`, `startMiningTx`, `pinCode`
+- `createMint`, `mintAuthorityAddress`, `allowExternalMintAuthorityAddress`
+- `createMelt`, `meltAuthorityAddress`, `allowExternalMeltAuthorityAddress`
+- `data`, `isCreateNFT`, `signTx`, `tokenVersion`
+
+WalletServiceWallet uses inline options object with similar but not identical fields.
+
+---
+
+## Part 6: Authority Methods Deep Dive
+
+Both facades have authority methods but with different return types:
+
+### HathorWallet
+```typescript
+getMintAuthority(tokenUid: string, options?: GetAuthorityOptions): Promise<IUtxo[]>
+getMeltAuthority(tokenUid: string, options?: GetAuthorityOptions): Promise<IUtxo[]>
+getAuthorityUtxo(tokenUid: string, authority: 'mint' | 'melt', options?: GetAuthorityOptions): Promise<IUtxo[]>
+
+// GetAuthorityOptions:
+{
+  many?: boolean;
+  only_available_utxos?: boolean;
+  filter_address?: string;
+}
+```
+
+### WalletServiceWallet
+```typescript
+getMintAuthority(tokenId: string, options?: { many?: boolean; skipSpent?: boolean }): Promise<AuthorityTxOutput[]>
+getMeltAuthority(tokenId: string, options?: { many?: boolean; skipSpent?: boolean }): Promise<AuthorityTxOutput[]>
+getAuthorityUtxo(tokenUid: string, authority: string, options?: {...}): Promise<AuthorityTxOutput[]>
+
+// AuthorityTxOutput:
+{
+  txId: string;
+  index: number;
+  address: string;
+  authorities: OutputValueType;
+}
+```
+
+### IUtxo vs AuthorityTxOutput
+
+| Field | IUtxo | AuthorityTxOutput |
+|-------|-------|-------------------|
+| txId | ✅ | ✅ |
+| index | ✅ | ✅ |
+| address | ✅ | ✅ |
+| authorities | ✅ | ✅ |
+| tokenId | ✅ | ❌ |
+| value | ✅ | ❌ |
+| timelock | ✅ | ❌ |
+| heightlock | ✅ | ❌ |
+| locked | ✅ | ❌ |
+| addressPath | ✅ | ❌ |
+
+---
+
+## Part 7: Prioritized Recommendations
+
+### Priority 1: Fix Critical Async/Sync Mismatches
+
+1. **Make `getCurrentAddress()` async in both facades**
+   - WalletServiceWallet needs to return `Promise<AddressInfoObject>`
+   - Update interface to `Promise<AddressInfoObject>`
+
+2. **Make `getNextAddress()` async in both facades**
+   - Same approach as above
+
+3. **Update `stop()` in interface to be async**
+   - Change interface from `void` to `Promise<void>`
+   - Both facades already return Promise
+
+### Priority 2: Unify Return Types
+
+1. **Standardize authority method returns**
+   - Define a common `AuthorityUtxo` type
+   - Update both facades to return the same structure
+   - Add methods to interface
+
+2. **Standardize `sendTransaction()` return type**
+   - Decide: `Transaction` or `Transaction | null`
+   - HathorWallet returns `null` on certain conditions
+
+### Priority 3: Add Missing Interface Methods
+
+```typescript
+// Add to IHathorWallet:
+getMintAuthority(tokenUid: string, options?: AuthorityOptions): Promise<AuthorityUtxo[]>;
+getMeltAuthority(tokenUid: string, options?: AuthorityOptions): Promise<AuthorityUtxo[]>;
+isReady(): boolean;
+```
+
+### Priority 4: Type the Options Parameters
+
+Create explicit types for all options objects and use them in the interface.
+
+### Priority 5: Implement Missing Methods in WalletServiceWallet
+
+- `getTx()` - Consider implementing via API
+- `getAddressInfo()` - Consider implementing via API
+- `consolidateUtxos()` - May require backend support
+- `getFullHistory()` - Consider implementing via API
+
+---
+
+## Part 8: Shared Test Compatibility Matrix
+
+Based on the current state, here's what can be tested with the shared test factory:
+
+| Test Category | Compatible | Notes |
+|---------------|------------|-------|
+| Lifecycle (`start`/`stop`/`isReady`) | ✅ | Need to handle async stop |
+| Balance Operations | ✅ | Compatible |
+| Address Operations | ⚠️ | Need Promise.resolve() wrapper |
+| Simple Transactions | ✅ | Return type differs but compatible |
+| Multi-output Transactions | ✅ | Return type differs but compatible |
+| UTXO Operations | ✅ | Compatible |
+| Token Creation | ✅ | Compatible |
+| Token Details | ✅ | Compatible |
+| Mint Tokens | ⚠️ | WalletService has sync issues |
+| Melt Tokens | ⚠️ | WalletService has sync issues |
+| Authority Operations | ⚠️ | Different return types |
+| UTXO Consolidation | ❌ | Not implemented in WalletService |
+| Full History | ❌ | Not implemented in WalletService |
+| Address Info | ❌ | Not implemented in WalletService |
+| Nano Contracts | ✅ | Both implement |
+
+---
+
+## Appendix A: Method Count Summary
+
+| Category | HathorWallet | WalletServiceWallet | IHathorWallet |
+|----------|-------------|---------------------|---------------|
+| Total Methods | ~113 | ~75 | ~52 |
+| Async Methods | ~97 | ~62 | ~45 |
+| Sync Methods | ~16 | ~13 | ~4 |
+| Not Implemented | 0 | 4 | N/A |
+
+---
+
+## Appendix B: Files Referenced
+
+- `src/new/wallet.ts` - HathorWallet (Fullnode Facade) - ~3,372 lines
+- `src/wallet/wallet.ts` - HathorWalletServiceWallet - ~3,002 lines
+- `src/wallet/types.ts` - IHathorWallet interface and related types
+- `src/new/types.ts` - HathorWallet-specific types
+- `src/types.ts` - Shared types (IUtxo, OutputValueType, etc.)
\ No newline at end of file