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Critter Stack in Review: message loss fixes, clean shutdown and multi-tenancy

JasperFx shipped 72 tagged releases across Wolverine, Marten and shared libraries between October 12 and 30. The headline theme is a durable inbox and outbox hardening pass that closed about a dozen ways messages could go missing or run twice, much of it driven by community bug reports. For .NET developers running durable messaging, the review also covers performance fixes, cleaner shutdown and multi-tenant Marten changes.

CritterWatch 1.1 groups dead letters by failure cause and acts on each group at once

CritterWatch 1.1 groups dead letters by the failure that produced them, merging matches across every monitored service and database into one row. An operator can replay, archive, restore or discard a whole group as a single tracked operation with a required reason. The release also exposes the same loop through MCP, so teams running Wolverine can handle incidents faster and check whether replayed messages failed again.

Wolverine Best Practices Revisited: A-Frame and Handler Design

JasperFx rewrote the Wolverine best practices guide from scratch, replacing the 2023 version. The new guide centers on the A-Frame Architecture and gives concrete advice on splitting handlers, error handling, and at-least-once messaging rules. It is a practical reference for .NET teams building messaging systems with Wolverine.

CritterWatch 1.1, Bobcat 1.0 and AI Skills 1.17 ship; Stoat preview arrives

JasperFx shipped a coordinated Critter Stack release wave: CritterWatch 1.1, Bobcat 1.0, AI Skills 1.17 and a Stoat 0.5.0 preview. CritterWatch's MCP server now exposes 83 tools, and Bobcat 1.0 turns existing test methods into executable specifications. Worth a look if you run Wolverine or Marten in production or write integration tests on the .NET stack.

Succeeding with test automation using Bobcat

The Critter Stack team has described the test automation strategy behind Bobcat, its new spec-driven integration testing framework for .NET. The post, written by Jeremy Miller, lays out practices for tests that ship confidence, are cheap to write, run fast, stay reliable and explain their failures. It is a useful reference for .NET teams who want their CI results to be trusted as a merge gate.

Rebuilding Marten Projections Without Downtime with Wolverine 6.51 Warm-up Nodes

Wolverine 6.51 adds a warm-up node role for blue/green deployments. New nodes join the cluster only to rebuild new projection versions in Marten or Polecat, without handling messages or subscriptions. Combined with versioned projections and a side-effect gate, teams can catch up read models before switching traffic. This is a practical path to zero-downtime releases for event-sourced systems.

Serverless Wolverine Gets a Transactional Outbox in Wolverine 6.51

Wolverine 6.51 adds the DurabilityMode.ServerlessWithOutbox mode, letting handlers running on Cloud Run, AWS Lambda or Azure Functions keep the transactional outbox without always-on background agents. An externally triggered durability pass recovers messages that failed to send, and push receivers accept broker deliveries over HTTP. It is a useful option for teams on tight serverless budgets.