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Adding a second middleware broke our typescript types

Inngest engineers discovered that composing multiple TypeScript middleware functions caused step.run return types to collapse to empty objects due to non-idempotent Jsonify transformations. The issue stemmed from how TypeScript handled nested serialization types, where Jsonify<Jsonify<T>> failed to resolve correctly compared to a single application.

Background

Inngest is a serverless framework that allows developers to build durable background jobs and workflows using TypeScript. It relies heavily on type inference to ensure data integrity across distributed steps.

Source
Lobsters
Published
Jul 14, 2026 at 05:28 AM
Score
6.0 / 10