fix: resolve relative file: dependencies correctly with install-strategy=linked

[manzoorwanijk]

In continuation of our exploration of using install-strategy=linked in the Gutenberg monorepo, which powers the WordPress Block Editor, this is a follow up of the fixes from #8996.

When using install-strategy=linked, relative file: dependencies (e.g., file:./project2) fail with ENOENT because the path is resolved one level above the project root. For example, file:./project2 becomes file:../project2, causing npm to look for /Users/dan/Source/project2 instead of /Users/dan/Source/project1/project2.

In the isolated reifier, non-workspace file: dependencies are incorrectly classified as "external" dependencies. This routes them through the store extraction path (pacote.extract) instead of symlinking them directly like workspaces. A Link node's resolved value is relative to its node_modules/ location — that relative path becomes invalid when used from the store context.

This PR treats local file: dep targets found in fsChildren as local dependencies (alongside workspaces) so they get symlinked directly instead of extracted into the store:

• _makeIdealGraph: Skip nodes from root.external if they (or their Link target) are in idealTree.fsChildren.
• assignCommonProperties: Classify deps whose targets are in node.fsChildren as local dependencies instead of external.

References

Fixes #7549

[wraithgar]

manually applied just the code changes to my refactor branch and tests all passed.

$ git diff
diff --git a/workspaces/arborist/lib/arborist/isolated-reifier.js b/workspaces/arborist/lib/arborist/isolated-reifier.js
index 4fafe7736..dd0adb954 100644
--- a/workspaces/arborist/lib/arborist/isolated-reifier.js
+++ b/workspaces/arborist/lib/arborist/isolated-reifier.js
@@ -100,6 +100,9 @@ module.exports = cls => class IsolatedReifier extends cls {
 
     this.idealGraph.workspaces = await Promise.all(Array.from(idealTree.fsChildren.values(), w => this.workspaceProxy(w)))
     const processed = new Set()
+    // local `file:` deps are in fsChildren but are not workspaces.
+    // they are already handled as workspace-like proxies above and should not go through the external/store extraction path.
+    const localFsChildren = new Set(idealTree.fsChildren)
     const queue = [idealTree, ...idealTree.fsChildren]
     while (queue.length !== 0) {
       const next = queue.pop()
@@ -112,7 +115,7 @@ module.exports = cls => class IsolatedReifier extends cls {
           queue.push(edge.to)
         }
       })
-      if (!next.isProjectRoot && !next.isWorkspace && !next.inert) {
+      if (!next.isProjectRoot && !next.isWorkspace && !next.inert && !localFsChildren.has(next) && !localFsChildren.has(next.target)) {
         this.idealGraph.external.push(await this.externalProxy(next))
       }
     }
@@ -208,8 +211,11 @@ module.exports = cls => class IsolatedReifier extends cls {
 
     if (populateDeps) {
       const optionalDeps = edges.filter(edge => edge.optional).map(edge => edge.to.target)
-      result.localDependencies = await Promise.all(nonOptionalDeps.filter(n => n.isWorkspace).map(n => this.workspaceProxy(n)))
-      result.externalDependencies = await Promise.all(nonOptionalDeps.filter(n => !n.isWorkspace && !n.inert).map(n => this.externalProxy(n)))
+      // local file: deps (non-workspace fsChildren) should be treated as local dependencies, not external, so they get symlinked directly instead of being extracted into the store.
+      const fsChildSet = new Set(node.fsChildren)
+      const isLocal = (n) => n.isWorkspace || fsChildSet.has(n)
+      result.localDependencies = await Promise.all(nonOptionalDeps.filter(isLocal).map(n => this.workspaceProxy(n)))
+      result.externalDependencies = await Promise.all(nonOptionalDeps.filter(n => !isLocal(n) && !n.inert).map(n => this.externalProxy(n)))
       result.externalOptionalDependencies = await Promise.all(optionalDeps.filter(n => !n.inert).map(n => this.externalProxy(n)))
       result.dependencies = [
         ...result.externalDependencies,

[wraithgar]

We landed the refactor which means it's time to resolve conflicts. If you're comfortable doing that go ahead. If you're not just let us know and we'll help.