[Feature 07] Storage & Idempotency

[onlyhyde]

Overview

Implement persistent storage for transaction records and idempotency keys using SQLite.

Implementation Details

Files:

• internal/storage/interface.go - Storage interface
• internal/storage/sqlite.go - SQLite implementation
• internal/middleware/idempotency.go - Idempotency middleware

Storage Interface

type Storage interface {
    // Transactions
    CreateTransaction(ctx, tx *TransactionRecord) error
    UpdateTransaction(ctx, id string, updates map[string]interface{}) error
    GetTransaction(ctx, id string) (*TransactionRecord, error)
    GetTransactionByHash(ctx, txHash string) (*TransactionRecord, error)
    ListTransactions(ctx, filters map[string]interface{}, limit, offset int) ([]*TransactionRecord, error)

    // Idempotency
    GetIdempotencyKey(ctx, key string) (*IdempotencyRecord, error)
    SetIdempotencyKey(ctx, record *IdempotencyRecord) error
    CleanupExpiredIdempotencyKeys(ctx) error

    // Lifecycle
    Close() error
    Migrate(ctx) error
}

Data Models

TransactionRecord:

• ID, Network, TxHash, From, To, Amount, Asset
• Status (pending, confirmed, failed)
• CreatedAt, ConfirmedAt, ErrorMessage

IdempotencyRecord:

• Key, Response, CreatedAt, ExpiresAt

SQLite Setup

• WAL mode for better concurrency
• Parameterized queries (prevent SQL injection)
• Indexes on tx_hash, status, expires_at

Idempotency Middleware

• Check Idempotency-Key header on POST requests
• Return cached response if key exists
• Store response after successful processing
• Set X-Idempotency-Replayed: true header on replay

Acceptance Criteria

• Storage interface defined
• SQLite implementation with migrations
• Parameterized queries (no SQL injection)
• Idempotency middleware
• Cleanup job for expired keys
• Unit tests for storage operations
• Integration tests

Dependencies

• [Feature 03] API Server #22 API Server

Branch

feature/storage