inngest-middlewarelisted

# Inngest Middleware Master Inngest middleware to handle cross-cutting concerns like logging, error tracking, dependency injection, and data transformation. Middleware runs at key points in the function lifecycle, enabling powerful patterns for observability and shared functionality. > **These skills are focused on TypeScript.** For Python or Go, refer to the [Inngest documentation](https://www.inngest.com/llms.txt) for language-specific guidance. Core concepts apply across all languages. > **Note:** The middleware system was significantly rewritten in v4. The lifecycle hooks documented here reflect the v4 API. If migrating from v3, consult the [migration guide](https://www.inngest.com/docs-markdown/reference/typescript/v4/migrations/v3-to-v4) for details on breaking changes. ## What is Middleware? Middleware allows code to run at various points in an Inngest client's lifecycle - during function execution, event sending, and more. Think of middleware as hooks into the Inngest execution pipeline. **When to use middleware:** - **Observability:** Add logging, tracing, or metrics - **Dependency injection:** Share client instances across functions - **Data transformation:** Encrypt/decrypt, validate, or enrich data - **Error handling:** Custom error tracking and alerting - **Authentication:** Validate user context or permissions ## Middleware Lifecycle Middleware can be registered at **client-level** (affects all functions) or **function-level** (affects specific function