pqdevnet0: container specs

[unnawut]

🗒️ Description

Introducing the 1st draft of the container specs for pqdevnet-0.

🔗 Related Issues or PRs

• See the original question(s) at PQ Interop #4 | August 6, 2025 ethereum/pm#1663 (comment)

✅ Checklist

• Ran tox checks to avoid unnecessary CI fails:

  uvx --with=tox-uv tox

• Considered adding appropriate tests for the changes.
• Considered updating the online docs in the ./docs/ directory.

[fselmo]

Hey @unnawut. This looks good to me. It would be nice to try to share some types that the execution-specs team put together specifically for Ethereum types. I added that as a comment here. That would help with homogeneity across spec repos for users and for spec readers.

I'm also not sure if the pqdevnet should be under subspecs but feel free to arrange these dirs however you see best. If these are more general types, perhaps they belong under the lean_spec directory. But there's no reason they can't be moved to a broader scope when it makes sense to.

[unnawut]

From interop call Guillaume pointed out that zeam uses the union type for optional field which makes sense.

I'll try it out and update this PR accordingly.

[fselmo]

@unnawut ethereum/py-ssz also includes some relevant types that can potentially be leveraged here. I wonder at what point it makes sense to move these to ethereum-types as well but at least for now, things like List with max length, bitlist, etc could be useful. I would still pull things like U64, and whatever is already available, from ethereum-types, rather than py-ssz, to better align with the execution-specs types.

You can ignore my comment about moving types into ethereum-types (unless it makes sense for you to add more types there) as that's out of the scope for you and more of a thought for Python maintainers. But if it makes sense to use these types, that can also be a dependency that can be used in this repo and if they move, we can update here when the time comes.

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edit: I also ran the github workflow which triggered some fails on lint / formatting. I gave you write permissions here as well so this should run automatically for you on subsequent PRs.

[unnawut]

Closing in favor of #8. Will reopen this PR when there's more clarity around the specs format.