Allow future versions of pixi to read old pixi.toml files

[Yura52]

Problem description

Since backward incompatible changes in file formats are possible, pixi.toml written today can become invalid for future versions of pixi. It would be nice to guarantee that pixi.toml files, no matter how old, will remain compatible with future versions of pixi. More details, motivation and ideas can be found in this discussion.

P.S. My understanding is that pixi.lock are guaranteed to be compatible with future versions of pixi by setting the "version" key (example). If this is not true, than this issue applies to pixi.lock as well.

[gzm55]

Is it possible to lock the pixi binary version and toml version inside a pixi project (a directory with pixi.toml) with some in-project config and entrypoint script, then the new version binary should provide the migration method to convert old version pixi.toml to new version.

[baszalmstra]

I can safely say that with every change we make strive to be backward compatible. However, we cannot guarantee this while we are very actively developing on pixi. If however, breaking changes are made we will make the path to upgrade very easy.

I can see a future where we will add a version to the pixi.toml. But as long as we don't make backward-incompatible changes we most likely won't be adding it because there is no need (the absence of the field would imply version 0).

[baszalmstra]

Closing this for now.