Fix rebuild with resources.Concat

Fixes #12017

resources/resource.go

@@ -171,7 +171,7 @@ func (fd *ResourceSourceDescriptor) init(r *Spec) error {
 	fd.MediaType = mediaType
 
 	if fd.DependencyManager == nil {
-		fd.DependencyManager = identity.NopManager
+		fd.DependencyManager = r.Cfg.NewIdentityManager("resource")
 	}
 
 	return nil

resources/resource_cache.go

@@ -39,7 +39,7 @@ func newResourceCache(rs *Spec, memCache *dynacache.Cache) *ResourceCache {
 		cacheResources: dynacache.GetOrCreatePartition[string, resource.Resources](
 			memCache,
 			"/ress",
-			dynacache.OptionsPartition{ClearWhen: dynacache.ClearOnChange, Weight: 40},
+			dynacache.OptionsPartition{ClearWhen: dynacache.ClearOnRebuild, Weight: 40},
 		),
 		cacheResourceTransformation: dynacache.GetOrCreatePartition[string, *resourceAdapterInner](
 			memCache,

resources/resource_factories/bundler/bundler.go

@@ -20,6 +20,7 @@ import (
 	"path"
 
 	"github.com/gohugoio/hugo/common/hugio"
+	"github.com/gohugoio/hugo/identity"
 	"github.com/gohugoio/hugo/media"
 	"github.com/gohugoio/hugo/resources"
 	"github.com/gohugoio/hugo/resources/resource"
@@ -86,13 +87,32 @@ func (c *Client) Concat(targetPath string, r resource.Resources) (resource.Resou
 
 		// The given set of resources must be of the same Media Type.
 		// We may improve on that in the future, but then we need to know more.
-		for i, r := range r {
-			if i > 0 && r.MediaType().Type != resolvedm.Type {
-				return nil, fmt.Errorf("resources in Concat must be of the same Media Type, got %q and %q", r.MediaType().Type, resolvedm.Type)
+		for i, rr := range r {
+			if i > 0 && rr.MediaType().Type != resolvedm.Type {
+				return nil, fmt.Errorf("resources in Concat must be of the same Media Type, got %q and %q", rr.MediaType().Type, resolvedm.Type)
 			}
-			resolvedm = r.MediaType()
+			resolvedm = rr.MediaType()
 		}
 
+		idm := c.rs.Cfg.NewIdentityManager("concat")
+		// Add the concatenated resources as dependencies to the composite resource
+		// so that we can track changes to the individual resources.
+		idm.AddIdentityForEach(identity.ForEeachIdentityProviderFunc(
+			func(f func(identity.Identity) bool) bool {
+				var terminate bool
+				for _, rr := range r {
+					identity.WalkIdentitiesShallow(rr, func(depth int, id identity.Identity) bool {
+						terminate = f(id)
+						return terminate
+					})
+					if terminate {
+						break
+					}
+				}
+				return terminate
+			},
+		))
+
 		concatr := func() (hugio.ReadSeekCloser, error) {
 			var rcsources []hugio.ReadSeekCloser
 			for _, s := range r {
@@ -136,6 +156,7 @@ func (c *Client) Concat(targetPath string, r resource.Resources) (resource.Resou
 				LazyPublish:        true,
 				OpenReadSeekCloser: concatr,
 				TargetPath:         targetPath,
+				DependencyManager:  idm,
 			})
 		if err != nil {
 			return nil, err

resources/resource_factories/create/create.go

@@ -63,13 +63,6 @@ func (c *Client) Copy(r resource.Resource, targetPath string) (resource.Resource
 	})
 }
 
-func (c *Client) newDependencyManager() identity.Manager {
-	if c.rs.Cfg.Running() {
-		return identity.NewManager("resources")
-	}
-	return identity.NopManager
-}
-
 // Get creates a new Resource by opening the given pathname in the assets filesystem.
 func (c *Client) Get(pathname string) (resource.Resource, error) {
 	pathname = path.Clean(pathname)
@@ -79,7 +72,8 @@ func (c *Client) Get(pathname string) (resource.Resource, error) {
 		// The resource file will not be read before it gets used (e.g. in .Content),
 		// so we need to check that the file exists here.
 		filename := filepath.FromSlash(pathname)
-		if _, err := c.rs.BaseFs.Assets.Fs.Stat(filename); err != nil {
+		fi, err := c.rs.BaseFs.Assets.Fs.Stat(filename)
+		if err != nil {
 			if os.IsNotExist(err) {
 				return nil, nil
 			}
@@ -87,14 +81,16 @@ func (c *Client) Get(pathname string) (resource.Resource, error) {
 			return nil, err
 		}
 
+		pi := fi.(hugofs.FileMetaInfo).Meta().PathInfo
+
 		return c.rs.NewResource(resources.ResourceSourceDescriptor{
 			LazyPublish: true,
 			OpenReadSeekCloser: func() (hugio.ReadSeekCloser, error) {
 				return c.rs.BaseFs.Assets.Fs.Open(filename)
 			},
-			GroupIdentity:     identity.StringIdentity(key),
-			DependencyManager: c.newDependencyManager(),
-			TargetPath:        pathname,
+			Path:          pi,
+			GroupIdentity: pi,
+			TargetPath:    pathname,
 		})
 	})
 }