CosmJS 0.24, 0.25 and 0.26 all plan to support Cosmos SDK 0.40-0.42 under the name "Stargate".

Cosmos SDK 0.43 introduced some breaking changes in protobuf types, such that a client lib may only support either 0.42 or 0.43, but not both with the same code. It would require either making a new post-stargate package (which will become quite heavy to maintain, especially when 0.44 breaks it again), or making Stargate only support 0.43 and deprecating 0.42 support.

The most important chain to support is the Cosmos Hub. And ideally the majority of other mainnets. The question is when to enable 0.43 support and how. This issue is here to collect discussions on that point, as I know other projects have questions on this.