fix(arborist): surface undeclared workspaces under the linked strategy

[manzoorwanijk]

In continuation of our exploration of using install-strategy=linked in the Gutenberg monorepo, which powers the WordPress Block Editor.

Under install-strategy=linked, a declared workspace that the root does not depend on is installed on disk but was invisible to npm ls --all, npm ls --workspaces, and npm query ':root > *', all of which reported an empty tree. The hoisted strategy lists every workspace.

Undeclared workspaces are intentionally not symlinked into the root node_modules under the linked strategy, so when loadActual rebuilds the actual tree (from the filesystem scan or the hidden lockfile, neither of which records a node_modules/<ws> entry) the root's workspace edges resolve to nothing and the workspaces drop out of the tree that ls and query traverse. npm ls then hid those missing edges entirely to avoid a false UNMET DEPENDENCY.

The fix adds loadActual post-processing that, for the linked strategy, synthesizes an in-memory Link at node_modules/<ws> for each undeclared workspace so its root edge resolves, matching the logical layout the regular package-lock.json already records. This is introspection-only and writes nothing to disk. A declared workspace whose root link is genuinely missing is left alone so it still reports UNMET, an existing root child of the same name is never replaced, and a workspace that was not loaded is skipped. With the edges now resolving, the workspace-skip branch that npm ls used to suppress them is removed.

References

Fixes #9618

[manzoorwanijk]

@owlstronaut let us wrap this up. It may also need a manual backport.

EDIT: I am done for the day, please feel free to create a manual backport if needed, otherwise I will do it tomorrow.

[github-actions]

⚠️ Backport to release/v11 failed.

This usually means the cherry-pick had conflicts. Please create a manual backport:

git fetch origin release/v11
git checkout -b backport/v11/9657 origin/release/v11
git cherry-pick -x ae6dbeb12a6f4b313a28c99068e34ba834ae91d1
# resolve any conflicts, then:
git push origin backport/v11/9657

Error details

Command failed: git cherry-pick -x ae6dbeb12a6f4b313a28c99068e34ba834ae91d1
error: could not apply ae6dbeb12... fix(arborist): surface undeclared workspaces under the linked strategy (#9657)
hint: After resolving the conflicts, mark them with
hint: "git add/rm <pathspec>", then run
hint: "git cherry-pick --continue".
hint: You can instead skip this commit with "git cherry-pick --skip".
hint: To abort and get back to the state before "git cherry-pick",
hint: run "git cherry-pick --abort".
hint: Disable this message with "git config set advice.mergeConflict false"

[owlstronaut]

@manzoorwanijk I'll let you do it so my approval lets me merge it as well 😆

[manzoorwanijk]

Here is it is #9669