feat(orders): saga de orquestração liga o checkout ponta a ponta (fase 4b)

[thomasmoreira]

Summary by CodeRabbit

• New Features
  • Orders now progress through a coordinated workflow handling stock reservation, payment processing, and confirmation.
  • Automatic stock release when payment fails, ensuring inventory is properly restored during checkout.

[coderabbitai]

Caution

Review failed

Pull request was closed or merged during review

📝 Walkthrough

Walkthrough

This PR implements distributed order orchestration via a saga pattern. It introduces saga persistence, a coordinator that drives state transitions and emits corresponding outbox events, event consumers that respond to external service outcomes, and integration that ties saga initialization into order creation with comprehensive end-to-end tests.

Changes

Order Saga Orchestration

Layer / File(s)	Summary
Saga Persistence Model and Database src/Services/Orders/Saga/OrderSagaInstance.cs, src/Services/Orders/Infrastructure/OrderSagaInstanceConfiguration.cs, src/Services/Orders/Infrastructure/OrdersDbContext.cs, src/Services/Orders/Migrations/20260608171930_AddSagaState.cs, src/Services/Orders/Migrations/20260608171930_AddSagaState.Designer.cs, src/Services/Orders/Migrations/OrdersDbContextModelSnapshot.cs	OrderSagaInstance persists saga state (OrderId and State enum) in the orders.saga_state table. EF Core configuration maps the entity, context exposes a DbSet<OrderSagaInstance>, and migrations establish the table schema.
Saga Orchestration and Compensation Logic src/Contracts/CheckoutEvents.cs, src/Services/Orders/Saga/OrderSagaCoordinator.cs	OrderSagaCoordinator handles saga state transitions by loading persisted saga instances, advancing them via OrderSagaTrigger, and applying state-dependent side effects: confirms orders and emits OrderConfirmed, cancels orders and emits OrderCancelled, or compensates by emitting ReleaseStockRequested. The new ReleaseStockRequested contract carries order and stock details for compensation.
Event Consumers and Order Integration src/Services/Orders/Consumers/OrderSagaConsumers.cs, src/Services/Orders/Features/PlaceOrder.cs, src/Services/Orders/Program.cs	Five sealed consumers (StockReservedSagaConsumer, StockReservationFailedSagaConsumer, PaymentChargedSagaConsumer, PaymentFailedSagaConsumer, StockReleasedSagaConsumer) translate integration events into saga triggers. PlaceOrder initializes saga instances alongside order creation. Program.cs registers the coordinator, consumers, and RabbitMQ consumer for the "orders" queue.
Integration Tests tests/Integration/OrderSagaOrchestrationTests.cs	End-to-end tests boot Postgres, migrate schema, and validate three scenarios: happy path (stock + payment success → confirmed), stock failure (→ cancelled), and payment failure (→ compensation via release event, then cancelled).

Estimated code review effort

🎯 4 (Complex) | ⏱️ ~60 minutes

Poem

🐰 A saga's dance through states so grand,
Stock and payment, hand in hand,
Compensating when things go wrong,
Outbox events, steady and strong!
Distributed yet consistent, we prance,
In orchestrated sync—the rabbit's chance!

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 10.71% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title in Portuguese describes the implementation of an order saga orchestration that connects the checkout end-to-end (phase 4b), which directly aligns with the changeset that adds saga coordination, consumers, state persistence, and integration tests.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch feat/orders-saga

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