Fix panic on server atomic save edits on MacOS

An atomic save (write temp file, rename into place) unlinks the inode the
watcher holds, so kqueue reports Remove for a file that's still on disk.
That took the delete branch and wiped the entire taxonomy subtree; the
following assemble then panicked in createMissingTaxonomies, where the
shifting tree.Get hit a not yet assembled *pageMetaSource.

Treat Remove of a path that still exists as an update, and use the
non-shifting GetRaw when checking for the auto created taxonomy node.

Fixes #15130

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

hugolib/content_map_page_assembler.go

@@ -362,7 +362,7 @@ func (a *allPagesAssembler) doCreatePages(prefix string, depth int) error {
 
 		switch v := n.(type) {
 		case contentNodeSeq, contentNodes:
-			return handleContentNodeSeq(contentNodeToSeq(v))
+			return handleContentNodeSeq(cnh.contentNodeToSeq(v))
 		case *pageMetaSource:
 			n2, err = handlePageMetaSource(v, nil, false)
 			if err != nil {
@@ -781,7 +781,7 @@ func (a *allPagesAssembler) doCreatePages(prefix string, depth int) error {
 
 				if _, found := nodes[p.s.siteVector]; !found {
 					var rs *resourceSource
-					match := cnh.findContentNodeForSiteVector(p.s.siteVector, duplicateResourceFiles, contentNodeToSeq(n))
+					match := cnh.findContentNodeForSiteVector(p.s.siteVector, duplicateResourceFiles, cnh.contentNodeToSeq(n))
 					if match == nil {
 						return true
 					}
@@ -1385,8 +1385,11 @@ func (a *allPagesAssembler) createMissingTaxonomies() error {
 	for viewName, languages := range viewLanguages {
 		key := viewName.pluralTreeKey
 		if a.h.isRebuild() {
-			if v := tree.Get(key); v != nil {
-				// Already there.
+			// Note that we cannot use tree.Get here, as the tree at this point
+			// may hold not yet assembled *pageMetaSource nodes.
+			// We're only interested in whether the auto created (not file backed)
+			// taxonomy node is still there.
+			if n, found := tree.GetRaw(key); found && cnh.hasAutoContentNode(n) {
 				continue
 			}
 		}

hugolib/content_map_page_contentnode.go

@@ -28,6 +28,7 @@ var _ contentNode = (*contentNodeSeq)(nil)
 
 var (
 	_ contentNode                      = (*resourceSource)(nil)
+	_ contentNodeContentWeightProvider = (*pageMetaSource)(nil)
 	_ contentNodeContentWeightProvider = (*pageState)(nil)
 	_ contentNodeForSites              = (*pageState)(nil)
 	_ contentNodePage                  = (*contentNodes)(nil)
@@ -395,7 +396,15 @@ func contentNodeToContentNodesPage(n contentNode) (contentNodesMap, bool) {
 	}
 }
 
-func contentNodeToSeq(n contentNodeForEach) contentNodeSeq {
+// hasAutoContentNode reports whether n holds at least one node that is not backed by a file.
+func (h helperContentNode) hasAutoContentNode(n contentNodeForEach) bool {
+	return !n.forEeachContentNode(func(_ sitesmatrix.Vector, nn contentNode) bool {
+		wp, ok := nn.(contentNodeContentWeightProvider)
+		return ok && wp.contentWeight() > 0
+	})
+}
+
+func (h helperContentNode) contentNodeToSeq(n contentNodeForEach) contentNodeSeq {
 	if nn, ok := n.(contentNodeSeq); ok {
 		return nn
 	}
@@ -406,7 +415,7 @@ func contentNodeToSeq(n contentNodeForEach) contentNodeSeq {
 	}
 }
 
-func contentNodeToSeq2(n contentNodeForEach) contentNodeSeq2 {
+func (h helperContentNode) contentNodeToSeq2(n contentNodeForEach) contentNodeSeq2 {
 	if nn, ok := n.(contentNodeSeq2); ok {
 		return nn
 	}

hugolib/content_map_page_contentnodeshifter.go

@@ -105,7 +105,7 @@ func (s *contentNodeShifter) ForEeachInAllDimensions(n contentNode, f func(conte
 
 func (s *contentNodeShifter) ForEeachInDimension(n contentNode, vec sitesmatrix.Vector, d int, f func(contentNode) bool) {
 LOOP1:
-	for vec2, v := range contentNodeToSeq2(n) {
+	for vec2, v := range cnh.contentNodeToSeq2(n) {
 		for i, v := range vec2 {
 			if i != d && v != vec[i] {
 				continue LOOP1
@@ -170,7 +170,7 @@ func (s *contentNodeShifter) Shift(n contentNode, siteVector sitesmatrix.Vector,
 		}
 		// The exact match is an auto page (not backed by a file).
 		// Check if there's a file-backed complement that should take precedence.
-		if vvv := cnh.findContentNodeForSiteVector(siteVector, fallback, contentNodeToSeq(n)); vvv != nil {
+		if vvv := cnh.findContentNodeForSiteVector(siteVector, fallback, cnh.contentNodeToSeq(n)); vvv != nil {
 			return vvv, true
 		}
 		return exact, true
@@ -180,7 +180,7 @@ func (s *contentNodeShifter) Shift(n contentNode, siteVector sitesmatrix.Vector,
 		return nil, false
 	}
 
-	if vvv := cnh.findContentNodeForSiteVector(siteVector, fallback, contentNodeToSeq(n)); vvv != nil {
+	if vvv := cnh.findContentNodeForSiteVector(siteVector, fallback, cnh.contentNodeToSeq(n)); vvv != nil {
 		return vvv, true
 	}
 

hugolib/integrationtest_builder.go

@@ -231,11 +231,12 @@ type IntegrationTestBuilder struct {
 
 	Cfg IntegrationTestConfig
 
-	changedFiles []string
-	createdFiles []string
-	removedFiles []string
-	renamedFiles []string
-	renamedDirs  []string
+	changedFiles     []string
+	createdFiles     []string
+	removedFiles     []string
+	renamedFiles     []string
+	atomicSavedFiles []string
+	renamedDirs      []string
 
 	buildCount   int
 	GCCount      int
@@ -748,6 +749,14 @@ func (s *IntegrationTestBuilder) EditFileReplaceAll(filename, old, new string) *
 	})
 }
 
+// EditFileAtomicReplaceAll edits a file and simulates an editor atomic save by
+// emitting a fsnotify.Remove event for an existing path (see changeEvents).
+func (s *IntegrationTestBuilder) EditFileAtomicReplaceAll(filename, old, new string) *IntegrationTestBuilder {
+	return s.EditFileAtomicReplaceFunc(filename, func(s string) string {
+		return strings.ReplaceAll(s, old, new)
+	})
+}
+
 func (s *IntegrationTestBuilder) EditFileReplaceFunc(filename string, replacementFunc func(s string) string) *IntegrationTestBuilder {
 	absFilename := s.absFilename(filename)
 	b, err := afero.ReadFile(s.fs.Source, absFilename)
@@ -758,6 +767,16 @@ func (s *IntegrationTestBuilder) EditFileReplaceFunc(filename string, replacemen
 	return s
 }
 
+func (s *IntegrationTestBuilder) EditFileAtomicReplaceFunc(filename string, replacementFunc func(s string) string) *IntegrationTestBuilder {
+	absFilename := s.absFilename(filename)
+	b, err := afero.ReadFile(s.fs.Source, absFilename)
+	s.Assert(err, qt.IsNil)
+	s.atomicSavedFiles = append(s.atomicSavedFiles, absFilename)
+	oldContent := string(b)
+	s.writeSource(absFilename, replacementFunc(oldContent))
+	return s
+}
+
 func (s *IntegrationTestBuilder) EditFileAppend(filename, contnt string) *IntegrationTestBuilder {
 	absFilename := s.absFilename(filename)
 	b, err := afero.ReadFile(s.fs.Source, absFilename)
@@ -1043,6 +1062,7 @@ func (s *IntegrationTestBuilder) reset() {
 	s.createdFiles = nil
 	s.removedFiles = nil
 	s.renamedFiles = nil
+	s.atomicSavedFiles = nil
 }
 
 func (s *IntegrationTestBuilder) build(cfg BuildCfg) error {
@@ -1091,6 +1111,15 @@ func (s *IntegrationTestBuilder) changeEvents() []fsnotify.Event {
 		})
 	}
 
+	for _, v := range s.atomicSavedFiles {
+		events = append(events, fsnotify.Event{
+			Name: v,
+			// The watcher was watching the inode that got replaced by the rename,
+			// so we get a Remove for a file that's still on disk.
+			Op: fsnotify.Remove,
+		})
+	}
+
 	for _, v := range s.renamedDirs {
 		events = append(events, fsnotify.Event{
 			Name: v,

hugolib/page.go

@@ -225,10 +225,7 @@ func (ps *pageState) forEeachContentNode(f func(v sitesmatrix.Vector, n contentN
 }
 
 func (ps *pageState) contentWeight() int {
-	if ps.m.f == nil {
-		return 0
-	}
-	return ps.m.f.FileInfo().Meta().Weight
+	return ps.m.pageMetaSource.contentWeight()
 }
 
 func (ps *pageState) nodeSourceEntryID() any {

hugolib/page__meta.go

@@ -98,6 +98,13 @@ func (m *pageMetaSource) String() string {
 	return fmt.Sprintf("pageMetaSource(%s)", m.pathInfo)
 }
 
+func (m *pageMetaSource) contentWeight() int {
+	if m.f == nil {
+		return 0
+	}
+	return m.f.FileInfo().Meta().Weight
+}
+
 func (m *pageMetaSource) nodeCategoryPage() {
 	// Marker method.
 }

hugolib/page_test.go

@@ -2341,3 +2341,30 @@ layouts/s1/p3/_views/a.html
 	b.AssertFileContent("public/s1/p2/index.html", "p2: layouts/s1/_views/a.html")    // fails
 	b.AssertFileContent("public/s1/p3/index.html", "p3: layouts/s1/p3/_views/a.html") // fails
 }
+
+func TestPageConttentWeight(t *testing.T) {
+	files := `
+-- hugo.toml --
+-- content/mysection/page1.md --
+-- content/myothersection/page2.md --
+-- content/myothersection/_index.md --
+-- layouts/all.html --
+All.
+`
+	b := Test(t, files)
+
+	check := func(p page.Page, ok bool) {
+		cw := p.(contentNodeContentWeightProvider).contentWeight()
+		b.Assert(ok, qt.Equals, cw > 0)
+	}
+
+	s := b.H.Sites[0]
+	for _, p := range s.RegularPages() {
+		check(p, true)
+	}
+	check(s.home, false)
+	mysection, _ := s.GetPage("mysection")
+	check(mysection, false)
+	myothersection, _ := s.GetPage("myothersection") // backed by a content file.
+	check(myothersection, true)
+}

hugolib/rebuild_test.go

@@ -897,6 +897,17 @@ func TestRebuildEditSectionRemoveDate(t *testing.T) {
 	b.AssertFileContent("public/mysection/index.html", "all. My Section|Param: |Lastmod: 2021-02-01|")
 }
 
+// Atomic save (write temp file, then rename into place) of a section's branch bundle.
+// See issue 15130.
+func TestRebuildEditAtomicSection(t *testing.T) {
+	t.Parallel()
+	b := TestRunning(t, rebuildBasicFiles)
+	b.AssertFileContent("public/mysection/index.html", "My Section")
+	b.EditFileAtomicReplaceAll("content/mysection/_index.md", "My Section", "My Changed Section").Build()
+	b.AssertRenderCountPage(5)
+	b.AssertFileContent("public/mysection/index.html", "My Changed Section")
+}
+
 func TestRebuildVariations(t *testing.T) {
 	// t.Parallel() not supported, see https://github.com/fortytw2/leaktest/issues/4
 	// This leaktest seems to be a little bit shaky on Travis.
@@ -2170,3 +2181,33 @@ Foo.
 	b.EditFileReplaceAll("layouts/tags/list.html", "Foo", "Bar").Build()
 	b.AssertFileContent("public/tags/index.html", "Bar.")
 }
+
+// Atomic save (write temp file, then rename into place) of a content backed taxonomy root.
+// See issue 15130.
+func TestRebuildEditAtomicTaxonomyRoot(t *testing.T) {
+	t.Parallel()
+	files := `
+-- hugo.toml --
+baseURL = "https://example.com"
+disableLiveReload = true
+[taxonomies]
+object = "objects"
+-- content/objects/_index.md --
+---
+title: "Objects"
+---
+Objects content.
+-- content/p1.md --
+---
+title: "P1"
+objects: ["o1"]
+---
+-- layouts/all.html --
+{{ .Title }}|{{ .Kind }}|{{ .Content }}
+`
+	b := TestRunning(t, files)
+	b.AssertFileContent("public/objects/index.html", "Objects|taxonomy|<p>Objects content.</p>")
+	b.EditFileAtomicReplaceAll("content/objects/_index.md", "Objects content.", "Objects content edited.").Build()
+	b.AssertFileContent("public/objects/index.html", "Objects|taxonomy|<p>Objects content edited.</p>")
+	b.AssertFileContent("public/objects/o1/index.html", "O1|term|")
+}

hugolib/site.go

@@ -1257,20 +1257,14 @@ func (h *HugoSites) fileEventsApplyInfo(events []fsnotify.Event) []fileEventInfo
 		removed := false
 		added := false
 
-		if ev.Op&fsnotify.Remove == fsnotify.Remove {
-			removed = true
-		}
-
 		fi, statErr := h.Fs.Source.Stat(ev.Name)
 
-		// Some editors (Vim) sometimes issue only a Rename operation when writing an existing file
-		// Sometimes a rename operation means that file has been renamed other times it means
-		// it's been updated.
-		if ev.Op.Has(fsnotify.Rename) {
-			// If the file is still on disk, it's only been updated, if it's not, it's been moved
-			if statErr != nil {
-				removed = true
-			}
+		// Some editors (Vim) sometimes issue only a Rename operation when writing an existing file,
+		// and an atomic save (write temp file, then rename it into place) makes the watcher
+		// report the replaced file as removed (kqueue/macOS).
+		// So, if the file is still on disk, it's only been updated, if it's not, it's gone.
+		if ev.Op.Has(fsnotify.Remove) || ev.Op.Has(fsnotify.Rename) {
+			removed = statErr != nil
 		}
 		if ev.Op.Has(fsnotify.Create) {
 			added = true