[pavelzw]

Description

Stacked on #7385.

pixi publish (and pixi build, which forwards to it) built with exclude_newer: None, so neither the workspace's exclude-newer nor any other cutoff applied to the build and host dependencies of published packages. The same package built as a source dependency of the workspace did honor the cutoff, so publish could build against packages the workspace considers too new.

Publish now resolves the exclude-newer of the workspace's default environment (with channel cutoffs and exemptions, like a solve of that environment) and passes it to both the backend metadata and the package builds.

Standalone packages

Publishing a package without a workspace isn't supported yet: pixi publish on a package-only pixi.toml or a bare recipe.yaml fails with could not find pixi.toml or pyproject.toml with tool.pixi. Once it is, such a build has no manifest cutoff, and the default-exclude-newer of the configuration (#7385) is the natural fallback, like for pixi exec. That's not part of this PR, as there is no code path for it yet.

How Has This Been Tested?

Integration test: a package with a host dependency from a channel whose packages are all newer than the channel's exclude-newer fails to publish with "uploaded after the cutoff date", and publishes once the cutoff is removed.

AI Disclosure

• This PR contains AI-generated content.
  • I have tested any AI-generated content in my PR.
  • I take responsibility for any AI-generated content in my PR.

Tools: Claude Code

Checklist:

• I have performed a self-review of my own code
• I have made corresponding changes to the documentation
• I have added sufficient tests to cover my changes.
• I have verified that changes that would impact the JSON schema have been made in schema/model.py.

[pavelzw]

right now, pixi publish only works if there is a workspace anyway. in that case, we can also use the exclude-newer from said workspace.
might make things simpler?