[Host.Outbox.MongoDb] MongoDb Outbox plugin

[zarusz]

Add MongoDB Transactional Outbox Plugin

Adds SlimMessageBus.Host.Outbox.MongoDb — a new outbox plugin backed by MongoDB, mirroring the existing SQL/PostgreSQL plugins.

What's new

• AddOutboxUsingMongoDb() — configures the outbox with a MongoDB collection (smb_outbox) and an optional global lock collection (smb_outbox_lock)
• UseMongoDbTransaction() — wraps consumers in a MongoDB multi-document transaction (requires replica set); the outbox insert automatically participates in the active session
• IClientSessionHandle? constructor injection — consumers can inject the active session directly without any SMB dependency; works because of the core change below
• Versioned migrations — MongoDbOutboxMigrationService tracks applied schema changes in smb_outbox_migrations; can be disabled via EnableMigration = false
• Integration tests — Testcontainers (mongo:8.0) with per-test database isolation

Core SMB change

Consumer instances are now resolved from DI after all interceptors have run (lazy via ConsumerContext.ConsumerFactory), rather than before. This enables interceptors to set up ambient state (e.g. open a DB transaction) that is visible when the consumer's constructor fires.

[sonarqubecloud]

Quality Gate passed

Issues
9 New issues
0 Accepted issues

Measures
0 Security Hotspots
78.5% Coverage on New Code
1.6% Duplication on New Code

See analysis details on SonarQube Cloud