Wallets service balances

[MaryammAli]

Persist Wallet Balances Using TypeORM

Overview

This PR replaces the in-memory wallet balance storage implementation with persistent database-backed storage using TypeORM entities and repositories.

Problem Addressed

The current WalletsService stores balances in a plain in-memory Map, causing all wallet data to be lost whenever the application restarts, crashes, or scales horizontally.

This creates a critical data-loss issue for the wallet system and makes balances unreliable in any real deployment environment.

Changes Made

• Added a new WalletBalance TypeORM entity with the following fields:

  • id
  • accountId
  • currency
  • balance
  • createdAt
  • updatedAt

• Refactored WalletsService to use InjectRepository(WalletBalance) for all balance operations.

• Replaced in-memory balance handling with persistent database reads/writes.

• Implemented transactional adjustBalance updates with optimistic locking to prevent race conditions and concurrent update inconsistencies.

• Replaced:

  • getBalance
  • getBalancesForAccount

  with TypeORM-backed queries.

• Added TypeOrmModule.forFeature([WalletBalance]) to the wallet module.

• Added a TypeORM migration for wallet balance persistence.

• Added unit tests covering:

  • balance persistence
  • concurrent updates
  • retrieval queries
  • transactional behavior

Key Files Updated

• src/wallet/wallets.service.ts
• src/wallet/wallets.types.ts
• src/wallet/wallets.module.ts
• New WalletBalance entity and migration files

Acceptance Criteria

• Wallet balances persist across application restarts.
• adjustBalance operations are atomic and concurrency-safe.
• Existing wallet service methods pass unit tests against a test database.
• TypeORM migration file is included in the PR.

Notes

• This update significantly improves wallet reliability and production readiness.
• Existing wallet APIs remain compatible while moving persistence to the database layer.
• Optimistic locking helps prevent incorrect balance totals during concurrent balance updates.
  Closes [Wave 200pts] WalletsService: balances are stored in-memory Map — all wallet data lost on every restart #549

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@MaryammAli Great news! 🎉 Based on an automated assessment of this PR, the linked Wave issue(s) no longer count against your application limits.

You can now already apply to more issues while waiting for a review of this PR. Keep up the great work! 🚀

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[portableDD]

@MaryammAli please resolve conflict

[MaryammAli]

@portableDD
conflict resolved

[MaryammAli]

@portableDD
conflict resolved