"Why can't you nest a pipeline inside a pipeline?  What's the difference between a mode and a preset?  What's a solid?" As we look towards a 1.0 release, we want a set of core APIs that will stand the test of time.  In the last couple months, we've collected feedback from users on the least intuitive aspects of Dagster and used that feedback to plan a set of final changes to the core APIs. These changes are significant and impactful, including major renames (for example, 

@solid

 will become 

@op

) , unification of concepts such as modes and presets, and separation of DAG definitions from their resources and default config. Yesterday we published a blog post describing these changes and why we're making them, as well as a migration guide with side-by-side examples.  We believe these APIs, and the corresponding Dagit changes, are a huge step forward for testing, elegance, deployment, and verbosity.  While currently experimental in Dagster 0.12.x, they'll serve as the foundation of Dagster starting in 0.13.0.  We need your feedback to make this awesome. We’d love for you to try them out, and then to tell us how we can improve.