feat: add multi-unit support (sat, usd, auth, etc.) by 4xvgal · Pull Request #88 · cashubtc/coco

4xvgal · 2026-02-06T07:35:30Z

Description

This PR adds multi-unit support to the coco, allowing wallets to handle multiple currency units (sat, usd, auth,
etc.) per mint. Each mint can have multiple keysets with different units, and this implementation enables filtering proofs
and balances by unit.

Key changes:

Added unit field to SendOperation and MeltOperation types
Updated WalletService to cache wallets per mintUrl:unit combination
Added unit-based proof filtering in ProofService
Updated all repository implementations to persist the unit field
Maintained full backward compatibility with 'sat' as the default unit

Notes to the reviewers

Backward Compatibility: All unit parameters default to 'sat', so existing code continues to work without changes. When
reading old database rows without a unit field, it defaults to 'sat'.
No Database Migration Required: The unit field is optional in row types and defaults to 'sat' when null/undefined.
Existing data works seamlessly.
API Changes:
- WalletApi.send(mintUrl, amount, unit = 'sat') - added optional unit parameter
- ProofService.selectProofsToSend(mintUrl, amount, unit = 'sat', includeFees) - unit is now the 3rd parameter
- New methods: getBalancesByUnit(), getSupportedUnits(mintUrl), getReadyProofsByUnit(mintUrl, unit)
Test Coverage: Added multi-unit test suite in ProofService.test.ts with 4 new tests covering unit-based balance and
proof filtering.

Suggested CHANGELOG Updates

ADDED

WalletApi.getBalancesByUnit() - Get balances grouped by mint and unit
WalletApi.getSupportedUnits(mintUrl) - Get list of supported units for a mint
ProofService.getBalancesByUnit() - Get all balances grouped by mint and unit
ProofService.getReadyProofsByUnit(mintUrl, unit) - Get ready proofs filtered by unit
unit field to SendOperation and MeltOperation types
Multi-unit test suite in ProofService.test.ts

MODIFIED

WalletService.getWallet(mintUrl, unit = 'sat') - Added optional unit parameter
WalletService.getWalletWithActiveKeysetId(mintUrl, unit = 'sat') - Added optional unit parameter
WalletService.clearCache(mintUrl, unit?) - Added optional unit parameter
WalletService.refreshWallet(mintUrl, unit = 'sat') - Added optional unit parameter
ProofService.getBalance(mintUrl, unit = 'sat') - Added optional unit parameter
ProofService.selectProofsToSend(mintUrl, amount, unit = 'sat', includeFees) - Added unit parameter
WalletApi.send(mintUrl, amount, unit = 'sat') - Added optional unit parameter
SendOperationService.init(mintUrl, amount, unit = 'sat') - Added optional unit parameter
SendOperationService.send(mintUrl, amount, unit = 'sat') - Added optional unit parameter
MeltOperationService.init(mintUrl, method, methodData, unit = 'sat') - Added optional unit parameter
All repository implementations (sqlite3, expo-sqlite, indexeddb) to support unit field

REMOVED

None

Support multiple currency units per mint by adding unit field to operations and filtering proofs by keyset unit. Backward compatible with 'sat' as default.

changeset-bot · 2026-02-06T07:35:37Z

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Egge21M

Thank you so much for taking on this challenge! It would be amazing to have this in for the stable v1 release.

packages/sqlite3/src/repositories/SendOperationRepository.ts

packages/core/operations/send/SendOperationService.ts

packages/core/services/ProofService.ts

- Add unit parameter to MintQuoteService.createMintQuote (default: 'sat') - Update redeemMintQuote to use quote.unit when getting wallet - Add unit parameter to QuotesApi.createMintQuote - Add unit tests for createMintQuote with different units - Complete multi-unit integration tests (remove TODO placeholders)

packages/core/services/MintQuoteService.ts

Egge21M · 2026-02-12T11:32:48Z

packages/sqlite3/src/repositories/MeltOperationRepository.ts

@@ -82,6 +84,7 @@ const operationToParams = (operation: MeltOperation): unknown[] => {
    return [
      operation.id,


operationToParams() now includes operation.unit, but the create() INSERT column list still omits unit while passing params. That creates a bindings-count mismatch at runtime when persisting melt operations. Add unit to the INSERT columns/placeholders to match params.

Fixed. Unit column and placeholder added to the INSERT statement.
Coulumn count 18 matches operationToParams()

Egge21M · 2026-02-12T11:32:48Z

packages/expo-sqlite/src/repositories/MeltOperationRepository.ts

@@ -82,6 +84,7 @@ const operationToParams = (operation: MeltOperation): unknown[] => {
    return [
      operation.id,


Same issue as sqlite3 repo: operationToParams() includes unit, but create() INSERT still has the old column list. This will fail with a parameter/placeholder mismatch on melt operation creation. Please include unit in INSERT columns/placeholders.

same as above, unit added.

Egge21M · 2026-02-12T11:32:48Z

packages/expo-sqlite/src/repositories/SendOperationRepository.ts

@@ -67,6 +69,7 @@ function operationToParams(op: SendOperation): unknown[] {
    return [
      op.id,


operationToParams() now returns op.unit, but create() INSERT still omits the unit column. That causes binding mismatch when creating send operations in expo-sqlite. Add unit to the INSERT column list and placeholders.

unit added to INSERT column list (13 columns, 13 params)

Egge21M · 2026-02-12T11:32:48Z

packages/core/repositories/memory/MemoryProofRepository.ts

    return results;
  }

-  async getAvailableProofs(mintUrl: string): Promise<CoreProof[]> {


ProofRepository now requires getAvailableProofs(mintUrl, unit), but this implementation still declares only mintUrl. This breaks assignability/typecheck (and bypasses unit filtering in memory adapter). Please update the signature and filter ready proofs by unit via keyset mapping, consistent with other repositories.

Matched Decalres

Signature updated to getAvailableProofts(mintUrl, unit). Filters proofs by resolving proof.id -> keyset -> keyset.unit, consistent with SQL JOIN approach in other repositories

Egge21M

Great progress on multi-unit support, but there are a few correctness gaps we need to tackle before merging. One is technically not a bug, but a "behavior" issue that I think should be fixed

Egge21M · 2026-02-18T09:19:56Z

packages/indexeddb/src/repositories/ProofRepository.ts

+    // First, get keyset IDs for this unit
+    const keysets = (await (this.db as any)
+      .table('coco_cashu_keysets')
+      .where('[mintUrl+unit]')


This compound index is not part of the schema

Egge21M · 2026-02-18T09:27:18Z

packages/core/services/ProofService.ts

+    if (!unit || unit.trim().length === 0) {
+      throw new ProofValidationError('unit is required');
+    }
+    const keysetIds = await this.getKeysetIdsForUnit(mintUrl, unit);


This turns the getBalance() call into something that relies on networking. Looking at the big picture of supporting as many offline-first use cases as we can, we should avoid network calls when acting on local data.

Balance is the sum of all proofs that we have stored. We should not have any proofs of unknown keysets stored. So I think it would be best to have this act only on local data (even if there is a tiny chance of it being incomplete)

Egge21M · 2026-02-18T09:29:39Z

packages/core/services/ProofService.ts

   * Gets balances for all mints by summing ready proof amounts.
   * @returns An object mapping mint URLs to their balances
   */
  async getBalances(): Promise<{ [mintUrl: string]: number }> {


This will mix units and sum them up into one number. I don't think that is desirable. We should probably add a unit param with default sat for backwards compatibility here

Egge21M

I did a more thorough review and noticed that there are still a few places where coco assumes sat as unit and things will break.

We use CDK for our integration tests and it support custom units. I think it would be easy to spot these issues by running the whole integration suite using a custom unit like "USD" against a USD cdk mint once.

Please let me know if you need help adjusting the integration test to do that

Egge21M · 2026-02-18T15:52:22Z

packages/core/services/ProofService.ts

    }
  }

  async createOutputsAndIncrementCounters(


This method is a critical part of all receive/swap flows and right now it defaults to sat.

Egge21M · 2026-02-18T15:53:58Z

packages/core/services/MintQuoteService.ts

-      const { wallet } = await this.walletService.getWalletWithActiveKeysetId(mintUrl);
+      const unit = quote.unit || 'sat';
+      const { wallet } = await this.walletService.getWalletWithActiveKeysetId(mintUrl, unit);
      const { keep } = await this.proofService.createOutputsAndIncrementCounters(mintUrl, {


The created outputs will be for unit: "sat". See: https://github.com/cashubtc/coco/pull/88/changes#r2823058504

Egge21M · 2026-02-18T15:55:23Z

packages/core/services/TransactionService.ts

    this.logger = logger;
  }

  async receive(token: Token | string): Promise<void> {


This method still assumes sat for all token

Egge21M · 2026-02-18T15:57:49Z

packages/core/services/ProofService.ts

    return preparedProofs;
  }

  async createBlankOutputs(amount: number, mintUrl: string): Promise<OutputData[]> {


This assumes sat unit

Egge21M · 2026-02-18T15:58:24Z

packages/core/services/ProofService.ts

   * @param serializedOutputData - The serialized output data containing secrets and blinding factors
   * @returns The recovered proofs (only unspent ones)
   */
  async recoverProofsFromOutputData(


This assumes sat unit

Egge21M · 2026-02-18T16:18:01Z

packages/core/services/HistoryService.ts

    const entry: Omit<ReceiveHistoryEntry, 'id'> = {
      type: 'receive',
      createdAt: Date.now(),
      unit: token.unit || 'sat',


This will default to sat as TransactionService.receive emits the event without unit

feat: add multi-unit support (sat, usd, etc.)

9da5602

Support multiple currency units per mint by adding unit field to operations and filtering proofs by keyset unit. Backward compatible with 'sat' as default.

github-project-automation bot added this to coco Feb 6, 2026

github-project-automation bot moved this to Backlog in coco Feb 6, 2026

Egge21M requested changes Feb 6, 2026

View reviewed changes

packages/sqlite3/src/repositories/SendOperationRepository.ts Show resolved Hide resolved

packages/core/operations/send/SendOperationService.ts Show resolved Hide resolved

packages/core/services/ProofService.ts Outdated Show resolved Hide resolved

4xvgal and others added 2 commits February 9, 2026 18:35

Merge branch 'master' into feat-multi-unit

03cb6c2

This was referenced Feb 10, 2026

DRAFT - feat: add CAT/BAT (NUT-21/22) authentication support #92

Closed

feat: add CAT/BAT (NUT-21/22) authentication support #94

Draft

Egge21M requested changes Feb 12, 2026

View reviewed changes

Egge21M requested a review from robwoodgate February 12, 2026 12:29

fix: align unit column in repository INSERT/query across all adapters

8ec98fe

4xvgal force-pushed the feat-multi-unit branch from ed7a0fb to 8ec98fe Compare February 13, 2026 09:21

Egge21M requested changes Feb 18, 2026

View reviewed changes

		@@ -82,6 +84,7 @@ const operationToParams = (operation: MeltOperation): unknown[] => {
		return [
		operation.id,

		@@ -67,6 +69,7 @@ function operationToParams(op: SendOperation): unknown[] {
		return [
		op.id,

Conversation

4xvgal commented Feb 6, 2026

Description

Key changes:

Notes to the reviewers

Suggested CHANGELOG Updates

ADDED

MODIFIED

REMOVED

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changeset-bot bot commented Feb 6, 2026 •

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