How to make Shared Tree Shaking work with custom splitChunks cacheGroups?

[evynore]

Hi,

We're using Module Federation Enhanced's Shared Tree Shaking together with Rspack.

However, Shared Tree Shaking appears to stop working when custom splitChunks.cacheGroups are configured for chunk grouping.

This creates a tradeoff:

With Shared Tree Shaking enabled and default chunking, builds generate a very large number of small chunks.
With custom splitChunks.cacheGroups, chunk count becomes manageable, but Shared Tree Shaking no longer seems to be applied.

Is this limitation expected?

If so, is there a recommended way to make Shared Tree Shaking work together with custom splitChunks.cacheGroups?

If this combination is not currently supported, would you consider adding support for it in the future?

Thanks.

[UnknownHawkins]

Probably answer: It's expected; you need to keep the shared modules in the same cacheGroup that Module Federation uses (defaultVendors or defaultShared). If you define custom cacheGroups, make sure they don't split the shared modules across chunks; you can set enforce: true and priority: 20 to override default, but still need to keep them in the same group. Or you can disable tree shaking and use `rspack