// Correct: exported fields with json tags
type OrderResult struct {
    ID     string  `json:"id"`
    Amount float64 `json:"amount"`
}

// Broken on resume: unexported fields are lost
type badResult struct {
    id string  // json.Unmarshal cannot see this
}

// Correct: context-aware HTTP call
Execute: func(ctx context.Context) (string, error) {
    req, _ := http.NewRequestWithContext(ctx, "POST", url, body)
    resp, err := client.Do(req)
    // ...
}

// Broken: ignores context, blocks indefinitely
Execute: func(ctx context.Context) (string, error) {
    resp, err := http.Post(url, "application/json", body) // no context!
    // ...
}

// Setup (once per application)
db, _ := sql.Open("postgres", "postgres://localhost/mydb")
storage, _ := saga.NewPostgresStorage(db, "transactions")
lock := saga.NewPostgresLock(db)

// Define and run a saga
tx, err := saga.NewTransaction("order-123", storage, saga.TransactionOptions{
    IdempotencyKey: "order-123-v1",
    Lock:           lock,
    Input:          map[string]any{"orderId": "123", "amount": 99.99},
})
if err != nil {
    log.Fatal(err)
}

err = tx.Run(ctx, func(ctx context.Context, tx *saga.Transaction) error {
    // Step 1: Reserve inventory
    reservation, err := saga.Step(ctx, tx, "reserve-inventory", saga.StepDefinition[string]{
        IdempotencyKey: "reserve-123",
        Execute: func(ctx context.Context) (string, error) {
            return inventory.Reserve(ctx, "SKU-001", 1)
        },
        Compensate: func(ctx context.Context, id string) error {
            return inventory.Release(ctx, id)
        },
    })
    if err != nil {
        return err
    }

    // Step 2: Charge payment (with retry)
    _, err = saga.Step(ctx, tx, "charge-payment", saga.StepDefinition[string]{
        IdempotencyKey: "charge-123",
        Execute: func(ctx context.Context) (string, error) {
            return gateway.Charge(ctx, 99.99)
        },
        Compensate: func(ctx context.Context, chargeID string) error {
            return gateway.Refund(ctx, chargeID)
        },
        Retry: &saga.RetryPolicy{Attempts: 3, BackoffMs: 1000},
    })
    if err != nil {
        return err
    }

    // Step 3: Ship order
    _, err = saga.Step(ctx, tx, "ship-order", saga.StepDefinition[string]{
        IdempotencyKey: "ship-123",
        Execute: func(ctx context.Context) (string, error) {
            return shipping.Ship(ctx, reservation)
        },
        Compensate: func(ctx context.Context, trackingID string) error {
            return shipping.Cancel(ctx, trackingID)
        },
    })
    return err
})

if errors.Is(err, saga.ErrExecutionTimeout) {
    // Workflow exceeded 15-minute limit
}

var compErr *saga.CompensationFailedError
if errors.As(err, &compErr) {
    log.Printf("Compensation failed at step: %s", compErr.FailedStep)
}