Refactor: add stable folder layout foundation

Backend/internal/bootstrap/service_test.go

@@ -2,8 +2,10 @@ package bootstrap
 
 import (
 	"encoding/json"
+	"errors"
 	"os"
 	"path/filepath"
+	"strings"
 	"testing"
 )
 
@@ -58,6 +60,10 @@ func TestEnsureBootstrapPOSIXSkeletonInitializesEmptyRoot(t *testing.T) {
 		filepath.Join(rootPath, "users", "settings.json"),
 		filepath.Join(rootPath, "users", "data.json"),
 		filepath.Join(rootPath, "users", "personals"),
+		filepath.Join(rootPath, "users", "personals", "personal-ronald", "settings.json"),
+		filepath.Join(rootPath, "users", "personals", "personal-ronald", "layout.json"),
+		filepath.Join(rootPath, "users", "personals", "personal-ronald", "home.json"),
+		filepath.Join(rootPath, "users", "personals", "personal-ronald", "tree"),
 	}
 
 	for _, path := range requiredPaths {
@@ -101,6 +107,25 @@ func TestEnsureBootstrapPOSIXSkeletonInitializesEmptyRoot(t *testing.T) {
 	if usersSettings["primaryAdminId"] != "admin-1" {
 		t.Fatalf("expected primary admin id admin-1, got %#v", usersSettings["primaryAdminId"])
 	}
+
+	personalSettings := readJSONFileForTest[map[string]any](t, filepath.Join(rootPath, "users", "personals", "personal-ronald", "settings.json"))
+	if personalSettings["type"] != "personal" {
+		t.Fatalf("expected personal settings type personal, got %#v", personalSettings["type"])
+	}
+	if personalSettings["name"] != "Ronald" {
+		t.Fatalf("expected personal name Ronald, got %#v", personalSettings["name"])
+	}
+	if personalSettings["slug"] != "ronald" {
+		t.Fatalf("expected personal slug ronald, got %#v", personalSettings["slug"])
+	}
+
+	personalHome := readJSONFileForTest[map[string]any](t, filepath.Join(rootPath, "users", "personals", "personal-ronald", "home.json"))
+	if personalHome["type"] != "personal-home" {
+		t.Fatalf("expected personal home type personal-home, got %#v", personalHome["type"])
+	}
+	if personalHome["title"] != "Ronald's Home" {
+		t.Fatalf("expected personal home title Ronald's Home, got %#v", personalHome["title"])
+	}
 }
 
 func TestCreateProjectHierarchyFolderOnDiskCreatesExpectedFolderShape(t *testing.T) {
@@ -142,6 +167,9 @@ func TestCreateProjectHierarchyFolderOnDiskCreatesExpectedFolderShape(t *testing
 	}
 
 	folderPayload := readJSONFileForTest[map[string]any](t, filepath.Join(createdFolderPath, "folder.json"))
+	if strings.TrimSpace(asStringForTest(folderPayload["id"])) == "" {
+		t.Fatalf("expected created folder to have stable id, got %#v", folderPayload["id"])
+	}
 	if folderPayload["name"] != "Design System" {
 		t.Fatalf("expected folder name Design System, got %#v", folderPayload["name"])
 	}
@@ -161,11 +189,307 @@ func TestCreateProjectHierarchyFolderOnDiskCreatesExpectedFolderShape(t *testing
 	}
 }
 
+func TestCreateProjectTreeFolderOnDiskCreatesExpectedFolderShape(t *testing.T) {
+	rootPath := filepath.Join(t.TempDir(), "POSIX")
+	service := NewService(nil, rootPath)
+
+	err := service.ensureBootstrapPOSIXSkeleton(
+		InstallationRecord{ID: "installation-1", Name: "MangoPig", Mode: "personal", Access: "local", Protocol: "http", Host: "localhost", IsBootstrapped: true},
+		AdminSummary{ID: "admin-1", Email: "ronald@example.com", DisplayName: "Ronald"},
+		namedRecord{ID: "org-1", Name: "Primary Organization", Slug: "primary-organization"},
+		namedRecord{ID: "dept-1", Name: "Primary Department", Slug: "primary-department"},
+		namedRecord{ID: "team-1", Name: "Primary Team", Slug: "primary-team"},
+		namedRecord{ID: "project-1", Name: "Primary Project", Slug: "primary-project"},
+	)
+	if err != nil {
+		t.Fatalf("ensure bootstrap POSIX skeleton: %v", err)
+	}
+
+	createdPath, createdSlug, err := service.createProjectTreeFolderOnDisk("primary-project", "", "Docs")
+	if err != nil {
+		t.Fatalf("createProjectTreeFolderOnDisk root folder: %v", err)
+	}
+	if createdPath != "projects/project-primary-project/tree/folder-docs" {
+		t.Fatalf("unexpected created path: %s", createdPath)
+	}
+	if createdSlug != "docs" {
+		t.Fatalf("unexpected created slug: %s", createdSlug)
+	}
+
+	createdFolderPath := filepath.Join(rootPath, "projects", "project-primary-project", "tree", "folder-docs")
+	for _, path := range []string{
+		filepath.Join(createdFolderPath, "folder.json"),
+		filepath.Join(createdFolderPath, "acl.json"),
+		filepath.Join(createdFolderPath, "children"),
+	} {
+		if _, err := os.Stat(path); err != nil {
+			t.Fatalf("expected path to exist %s: %v", path, err)
+		}
+	}
+
+	nestedPath, nestedSlug, err := service.createProjectTreeFolderOnDisk("primary-project", createdPath, "Research")
+	if err != nil {
+		t.Fatalf("createProjectTreeFolderOnDisk nested folder: %v", err)
+	}
+	if nestedPath != "projects/project-primary-project/tree/folder-docs/children/folder-research" {
+		t.Fatalf("unexpected nested path: %s", nestedPath)
+	}
+	if nestedSlug != "research" {
+		t.Fatalf("unexpected nested slug: %s", nestedSlug)
+	}
+}
+
+func TestRenameProjectHierarchyFolderOnDiskRenamesFolderShape(t *testing.T) {
+	rootPath := filepath.Join(t.TempDir(), "POSIX")
+	service := NewService(nil, rootPath)
+
+	err := service.ensureBootstrapPOSIXSkeleton(
+		InstallationRecord{ID: "installation-1", Name: "MangoPig", Mode: "personal", Access: "local", Protocol: "http", Host: "localhost", IsBootstrapped: true},
+		AdminSummary{ID: "admin-1", Email: "ronald@example.com", DisplayName: "Ronald"},
+		namedRecord{ID: "org-1", Name: "Primary Organization", Slug: "primary-organization"},
+		namedRecord{ID: "dept-1", Name: "Primary Department", Slug: "primary-department"},
+		namedRecord{ID: "team-1", Name: "Primary Team", Slug: "primary-team"},
+		namedRecord{ID: "project-1", Name: "Primary Project", Slug: "primary-project"},
+	)
+	if err != nil {
+		t.Fatalf("ensure bootstrap POSIX skeleton: %v", err)
+	}
+
+	createdPath, _, err := service.createProjectHierarchyFolderOnDisk("primary-project", "", "Design System")
+	if err != nil {
+		t.Fatalf("createProjectHierarchyFolderOnDisk root folder: %v", err)
+	}
+
+	nestedPath, _, err := service.createProjectHierarchyFolderOnDisk("primary-project", createdPath, "Research")
+	if err != nil {
+		t.Fatalf("createProjectHierarchyFolderOnDisk nested folder: %v", err)
+	}
+
+	previousPath, renamedPath, err := service.renameProjectHierarchyFolderOnDisk("primary-project", createdPath, "Platform Design")
+	if err != nil {
+		t.Fatalf("renameProjectHierarchyFolderOnDisk: %v", err)
+	}
+	if previousPath != createdPath {
+		t.Fatalf("expected previous path %s, got %s", createdPath, previousPath)
+	}
+	if renamedPath != "projects/project-primary-project/children/folder-platform-design" {
+		t.Fatalf("unexpected renamed path: %s", renamedPath)
+	}
+
+	if _, err := os.Stat(filepath.Join(rootPath, filepath.FromSlash(createdPath))); !os.IsNotExist(err) {
+		t.Fatalf("expected previous folder path to be gone, got err=%v", err)
+	}
+
+	renamedFolderPath := filepath.Join(rootPath, filepath.FromSlash(renamedPath))
+	if _, err := os.Stat(filepath.Join(renamedFolderPath, "children", filepath.Base(nestedPath))); err != nil {
+		t.Fatalf("expected nested child folder to move with renamed parent: %v", err)
+	}
+
+	folderPayload := readJSONFileForTest[map[string]any](t, filepath.Join(renamedFolderPath, "folder.json"))
+	if strings.TrimSpace(asStringForTest(folderPayload["id"])) == "" {
+		t.Fatalf("expected renamed folder to preserve stable id, got %#v", folderPayload["id"])
+	}
+	if folderPayload["name"] != "Platform Design" {
+		t.Fatalf("expected renamed folder name Platform Design, got %#v", folderPayload["name"])
+	}
+	if folderPayload["slug"] != "platform-design" {
+		t.Fatalf("expected renamed folder slug platform-design, got %#v", folderPayload["slug"])
+	}
+	if folderPayload["type"] != "folder" {
+		t.Fatalf("expected renamed folder type folder, got %#v", folderPayload["type"])
+	}
+}
+
+func TestRenameProjectTreeFolderOnDiskRenamesFolderShape(t *testing.T) {
+	rootPath := filepath.Join(t.TempDir(), "POSIX")
+	service := NewService(nil, rootPath)
+
+	err := service.ensureBootstrapPOSIXSkeleton(
+		InstallationRecord{ID: "installation-1", Name: "MangoPig", Mode: "personal", Access: "local", Protocol: "http", Host: "localhost", IsBootstrapped: true},
+		AdminSummary{ID: "admin-1", Email: "ronald@example.com", DisplayName: "Ronald"},
+		namedRecord{ID: "org-1", Name: "Primary Organization", Slug: "primary-organization"},
+		namedRecord{ID: "dept-1", Name: "Primary Department", Slug: "primary-department"},
+		namedRecord{ID: "team-1", Name: "Primary Team", Slug: "primary-team"},
+		namedRecord{ID: "project-1", Name: "Primary Project", Slug: "primary-project"},
+	)
+	if err != nil {
+		t.Fatalf("ensure bootstrap POSIX skeleton: %v", err)
+	}
+
+	createdPath, _, err := service.createProjectTreeFolderOnDisk("primary-project", "", "Docs")
+	if err != nil {
+		t.Fatalf("createProjectTreeFolderOnDisk root folder: %v", err)
+	}
+
+	previousPath, renamedPath, err := service.renameProjectTreeFolderOnDisk("primary-project", createdPath, "Specifications")
+	if err != nil {
+		t.Fatalf("renameProjectTreeFolderOnDisk: %v", err)
+	}
+	if previousPath != createdPath {
+		t.Fatalf("expected previous path %s, got %s", createdPath, previousPath)
+	}
+	if renamedPath != "projects/project-primary-project/tree/folder-specifications" {
+		t.Fatalf("unexpected renamed path: %s", renamedPath)
+	}
+
+	folderPayload := readJSONFileForTest[map[string]any](t, filepath.Join(rootPath, filepath.FromSlash(renamedPath), "folder.json"))
+	if folderPayload["name"] != "Specifications" {
+		t.Fatalf("expected renamed folder name Specifications, got %#v", folderPayload["name"])
+	}
+	if folderPayload["slug"] != "specifications" {
+		t.Fatalf("expected renamed folder slug specifications, got %#v", folderPayload["slug"])
+	}
+}
+
+func TestMoveProjectHierarchyFolderOnDiskMovesFolderToNewParent(t *testing.T) {
+	rootPath := filepath.Join(t.TempDir(), "POSIX")
+	service := NewService(nil, rootPath)
+
+	err := service.ensureBootstrapPOSIXSkeleton(
+		InstallationRecord{ID: "installation-1", Name: "MangoPig", Mode: "personal", Access: "local", Protocol: "http", Host: "localhost", IsBootstrapped: true},
+		AdminSummary{ID: "admin-1", Email: "ronald@example.com", DisplayName: "Ronald"},
+		namedRecord{ID: "org-1", Name: "Primary Organization", Slug: "primary-organization"},
+		namedRecord{ID: "dept-1", Name: "Primary Department", Slug: "primary-department"},
+		namedRecord{ID: "team-1", Name: "Primary Team", Slug: "primary-team"},
+		namedRecord{ID: "project-1", Name: "Primary Project", Slug: "primary-project"},
+	)
+	if err != nil {
+		t.Fatalf("ensure bootstrap POSIX skeleton: %v", err)
+	}
+
+	designPath, _, err := service.createProjectHierarchyFolderOnDisk("primary-project", "", "Design")
+	if err != nil {
+		t.Fatalf("create design folder: %v", err)
+	}
+	operationsPath, _, err := service.createProjectHierarchyFolderOnDisk("primary-project", "", "Operations")
+	if err != nil {
+		t.Fatalf("create operations folder: %v", err)
+	}
+	researchPath, _, err := service.createProjectHierarchyFolderOnDisk("primary-project", designPath, "Research")
+	if err != nil {
+		t.Fatalf("create research folder: %v", err)
+	}
+	nestedPath, _, err := service.createProjectHierarchyFolderOnDisk("primary-project", researchPath, "Interview Notes")
+	if err != nil {
+		t.Fatalf("create nested folder: %v", err)
+	}
+
+	previousPath, movedPath, err := service.moveProjectHierarchyFolderOnDisk("primary-project", researchPath, operationsPath)
+	if err != nil {
+		t.Fatalf("moveProjectHierarchyFolderOnDisk: %v", err)
+	}
+	if previousPath != researchPath {
+		t.Fatalf("expected previous path %s, got %s", researchPath, previousPath)
+	}
+	if movedPath != "projects/project-primary-project/children/folder-operations/children/folder-research" {
+		t.Fatalf("unexpected moved path: %s", movedPath)
+	}
+
+	if _, err := os.Stat(filepath.Join(rootPath, filepath.FromSlash(researchPath))); !os.IsNotExist(err) {
+		t.Fatalf("expected previous folder path to be gone, got err=%v", err)
+	}
+
+	movedFolderPath := filepath.Join(rootPath, filepath.FromSlash(movedPath))
+	if _, err := os.Stat(filepath.Join(movedFolderPath, "children", filepath.Base(nestedPath))); err != nil {
+		t.Fatalf("expected nested child folder to move with moved parent: %v", err)
+	}
+
+	folderPayload := readJSONFileForTest[map[string]any](t, filepath.Join(movedFolderPath, "folder.json"))
+	if strings.TrimSpace(asStringForTest(folderPayload["id"])) == "" {
+		t.Fatalf("expected moved folder to preserve stable id, got %#v", folderPayload["id"])
+	}
+	if folderPayload["name"] != "Research" {
+		t.Fatalf("expected moved folder name Research, got %#v", folderPayload["name"])
+	}
+	if folderPayload["slug"] != "research" {
+		t.Fatalf("expected moved folder slug research, got %#v", folderPayload["slug"])
+	}
+	if folderPayload["type"] != "folder" {
+		t.Fatalf("expected moved folder type folder, got %#v", folderPayload["type"])
+	}
+}
+
+func TestMoveProjectTreeFolderOnDiskMovesFolderToNewParent(t *testing.T) {
+	rootPath := filepath.Join(t.TempDir(), "POSIX")
+	service := NewService(nil, rootPath)
+
+	err := service.ensureBootstrapPOSIXSkeleton(
+		InstallationRecord{ID: "installation-1", Name: "MangoPig", Mode: "personal", Access: "local", Protocol: "http", Host: "localhost", IsBootstrapped: true},
+		AdminSummary{ID: "admin-1", Email: "ronald@example.com", DisplayName: "Ronald"},
+		namedRecord{ID: "org-1", Name: "Primary Organization", Slug: "primary-organization"},
+		namedRecord{ID: "dept-1", Name: "Primary Department", Slug: "primary-department"},
+		namedRecord{ID: "team-1", Name: "Primary Team", Slug: "primary-team"},
+		namedRecord{ID: "project-1", Name: "Primary Project", Slug: "primary-project"},
+	)
+	if err != nil {
+		t.Fatalf("ensure bootstrap POSIX skeleton: %v", err)
+	}
+
+	docsPath, _, err := service.createProjectTreeFolderOnDisk("primary-project", "", "Docs")
+	if err != nil {
+		t.Fatalf("create docs folder: %v", err)
+	}
+	archivePath, _, err := service.createProjectTreeFolderOnDisk("primary-project", "", "Archive")
+	if err != nil {
+		t.Fatalf("create archive folder: %v", err)
+	}
+
+	previousPath, movedPath, err := service.moveProjectTreeFolderOnDisk("primary-project", docsPath, archivePath)
+	if err != nil {
+		t.Fatalf("moveProjectTreeFolderOnDisk: %v", err)
+	}
+	if previousPath != docsPath {
+		t.Fatalf("expected previous path %s, got %s", docsPath, previousPath)
+	}
+	if movedPath != "projects/project-primary-project/tree/folder-archive/children/folder-docs" {
+		t.Fatalf("unexpected moved path: %s", movedPath)
+	}
+
+	folderPayload := readJSONFileForTest[map[string]any](t, filepath.Join(rootPath, filepath.FromSlash(movedPath), "folder.json"))
+	if folderPayload["name"] != "Docs" {
+		t.Fatalf("expected moved folder name Docs, got %#v", folderPayload["name"])
+	}
+	if folderPayload["slug"] != "docs" {
+		t.Fatalf("expected moved folder slug docs, got %#v", folderPayload["slug"])
+	}
+}
+
+func TestMoveProjectHierarchyFolderOnDiskRejectsDescendantTarget(t *testing.T) {
+	rootPath := filepath.Join(t.TempDir(), "POSIX")
+	service := NewService(nil, rootPath)
+
+	err := service.ensureBootstrapPOSIXSkeleton(
+		InstallationRecord{ID: "installation-1", Name: "MangoPig", Mode: "personal", Access: "local", Protocol: "http", Host: "localhost", IsBootstrapped: true},
+		AdminSummary{ID: "admin-1", Email: "ronald@example.com", DisplayName: "Ronald"},
+		namedRecord{ID: "org-1", Name: "Primary Organization", Slug: "primary-organization"},
+		namedRecord{ID: "dept-1", Name: "Primary Department", Slug: "primary-department"},
+		namedRecord{ID: "team-1", Name: "Primary Team", Slug: "primary-team"},
+		namedRecord{ID: "project-1", Name: "Primary Project", Slug: "primary-project"},
+	)
+	if err != nil {
+		t.Fatalf("ensure bootstrap POSIX skeleton: %v", err)
+	}
+
+	parentPath, _, err := service.createProjectHierarchyFolderOnDisk("primary-project", "", "Parent")
+	if err != nil {
+		t.Fatalf("create parent folder: %v", err)
+	}
+	childPath, _, err := service.createProjectHierarchyFolderOnDisk("primary-project", parentPath, "Child")
+	if err != nil {
+		t.Fatalf("create child folder: %v", err)
+	}
+
+	_, _, err = service.moveProjectHierarchyFolderOnDisk("primary-project", parentPath, childPath)
+	if !errors.Is(err, ErrInvalidProjectFolderMove) {
+		t.Fatalf("expected ErrInvalidProjectFolderMove, got %v", err)
+	}
+}
+
 func TestBuildProjectHierarchyFolderTreeBuildsNestedStructure(t *testing.T) {
 	rows := []projectHierarchyFolderRow{
-		{Path: "projects/project-primary-project/children/folder-design", ParentPath: projectHierarchyRootPath("primary-project"), Label: "Design"},
-		{Path: "projects/project-primary-project/children/folder-design/children/folder-research", ParentPath: "projects/project-primary-project/children/folder-design/children", Label: "Research"},
-		{Path: "projects/project-primary-project/children/folder-ops", ParentPath: projectHierarchyRootPath("primary-project"), Label: "Ops"},
+		{ID: "folder-design-id", Path: "projects/project-primary-project/children/folder-design", ParentPath: projectHierarchyRootPath("primary-project"), Label: "Design"},
+		{ID: "folder-research-id", Path: "projects/project-primary-project/children/folder-design/children/folder-research", ParentPath: "projects/project-primary-project/children/folder-design/children", Label: "Research"},
+		{ID: "folder-ops-id", Path: "projects/project-primary-project/children/folder-ops", ParentPath: projectHierarchyRootPath("primary-project"), Label: "Ops"},
 	}
 
 	folders := buildProjectHierarchyFolderTree(rows, projectHierarchyRootPath("primary-project"))
@@ -178,6 +502,64 @@ func TestBuildProjectHierarchyFolderTreeBuildsNestedStructure(t *testing.T) {
 	if len(folders[0].Children) != 1 || folders[0].Children[0].Label != "Research" {
 		t.Fatalf("unexpected nested folder structure: %#v", folders[0].Children)
 	}
+	if folders[0].ID != "folder-design-id" || folders[0].Path != "projects/project-primary-project/children/folder-design" {
+		t.Fatalf("expected design folder to retain stable id/path, got %#v", folders[0])
+	}
+	if folders[0].Children[0].ID != "folder-research-id" || folders[1].ID != "folder-ops-id" {
+		t.Fatalf("expected nested/top-level folder ids to be preserved, got %#v / %#v", folders[0].Children[0], folders[1])
+	}
+}
+
+func TestApplyProjectHierarchyFolderOrderingOrdersRootAndChildrenByStableID(t *testing.T) {
+	folders := []ProjectHierarchyFolderRecord{
+		{
+			ID:    "folder-design-id",
+			Path:  "projects/project-primary-project/children/folder-design",
+			Label: "Design",
+			Children: []ProjectHierarchyFolderRecord{
+				{ID: "folder-research-id", Path: "projects/project-primary-project/children/folder-design/children/folder-research", Label: "Research"},
+				{ID: "folder-assets-id", Path: "projects/project-primary-project/children/folder-design/children/folder-assets", Label: "Assets"},
+			},
+		},
+		{ID: "folder-ops-id", Path: "projects/project-primary-project/children/folder-ops", Label: "Ops"},
+		{ID: "folder-qa-id", Path: "projects/project-primary-project/children/folder-qa", Label: "QA"},
+	}
+
+	ordered := applyProjectHierarchyFolderOrdering(folders, map[string][]string{
+		projectFolderOrderRootKey: {"folder-qa-id", "folder-design-id"},
+		"folder-design-id":        {"folder-assets-id", "folder-research-id"},
+	})
+
+	if len(ordered) != 3 {
+		t.Fatalf("expected 3 ordered root folders, got %d", len(ordered))
+	}
+	if ordered[0].ID != "folder-qa-id" || ordered[1].ID != "folder-design-id" || ordered[2].ID != "folder-ops-id" {
+		t.Fatalf("unexpected ordered root ids: %#v", ordered)
+	}
+	if len(ordered[1].Children) != 2 {
+		t.Fatalf("expected design folder children to be preserved, got %#v", ordered[1].Children)
+	}
+	if ordered[1].Children[0].ID != "folder-assets-id" || ordered[1].Children[1].ID != "folder-research-id" {
+		t.Fatalf("unexpected ordered child ids: %#v", ordered[1].Children)
+	}
+}
+
+func TestInsertFolderOrderReordersWithinSameParent(t *testing.T) {
+	folderOrder := map[string][]string{
+		projectFolderOrderRootKey: {"folder-a", "folder-b", "folder-c"},
+	}
+
+	insertFolderOrder(folderOrder, "", "folder-c", 0)
+
+	got := folderOrder[projectFolderOrderRootKey]
+	if len(got) != 3 || got[0] != "folder-c" || got[1] != "folder-a" || got[2] != "folder-b" {
+		t.Fatalf("unexpected reordered root children: %#v", got)
+	}
+}
+
+func asStringForTest(value any) string {
+	text, _ := value.(string)
+	return text
 }
 
 func readJSONFileForTest[T any](t *testing.T, path string) T {

Backend/internal/httpx/api_project_routes.go

@@ -17,6 +17,23 @@ type createProjectFolderRequest struct {
 	ParentFolderID string `json:"parentFolderId"`
 }
 
+type renameProjectFolderRequest struct {
+	FolderID string `json:"folderId"`
+	Name     string `json:"name"`
+}
+
+type deleteProjectFolderRequest struct {
+	FolderID string `json:"folderId"`
+}
+
+type moveProjectFolderRequest struct {
+	FolderID       string `json:"folderId"`
+	FolderNodeID   string `json:"folderNodeId"`
+	ParentFolderID string `json:"parentFolderId"`
+	ParentNodeID   string `json:"parentNodeId"`
+	TargetIndex    int    `json:"targetIndex"`
+}
+
 func (routes apiRoutes) handleProjectFolders(w http.ResponseWriter, r *http.Request) {
 	projectID := strings.TrimSpace(chi.URLParam(r, "projectId"))
 	if projectID == "" {
@@ -26,7 +43,7 @@ func (routes apiRoutes) handleProjectFolders(w http.ResponseWriter, r *http.Requ
 
 	folders, err := routes.bootstrapService().GetProjectHierarchyFolders(r.Context(), projectID)
 	if err != nil {
-		routes.writeProjectFolderError(w, r, err)
+		routes.writeProjectFolderError(w, r, err, "load")
 		return
 	}
 
@@ -66,7 +83,7 @@ func (routes apiRoutes) handleCreateProjectFolder(w http.ResponseWriter, r *http
 		Name:           payload.Name,
 	})
 	if err != nil {
-		routes.writeProjectFolderError(w, r, err)
+		routes.writeProjectFolderError(w, r, err, "persist")
 		return
 	}
 
@@ -79,20 +96,370 @@ func (routes apiRoutes) handleCreateProjectFolder(w http.ResponseWriter, r *http
 	})
 }
 
-func (routes apiRoutes) writeProjectFolderError(w http.ResponseWriter, r *http.Request, err error) {
+func (routes apiRoutes) handleDeleteProjectFolder(w http.ResponseWriter, r *http.Request) {
+	projectID := strings.TrimSpace(chi.URLParam(r, "projectId"))
+	if projectID == "" {
+		WriteError(w, http.StatusBadRequest, RequestIDFromContext(r.Context()), "invalid_request", "Project ID is required.")
+		return
+	}
+
+	payload := decodeDeleteProjectFolderRequest(r)
+	if strings.TrimSpace(payload.FolderID) == "" {
+		WriteError(w, http.StatusBadRequest, RequestIDFromContext(r.Context()), "invalid_request", "Folder ID is required.")
+		return
+	}
+
+	result, err := routes.bootstrapService().DeleteProjectFolder(r.Context(), bootstrapservice.DeleteProjectFolderInput{
+		ProjectID: projectID,
+		FolderID:  payload.FolderID,
+	})
+	if err != nil {
+		routes.writeProjectFolderError(w, r, err, "delete")
+		return
+	}
+
+	WriteJSON(w, http.StatusOK, map[string]any{
+		"data": result,
+		"meta": map[string]any{
+			"resource":  "project-folder-delete",
+			"persisted": true,
+		},
+	})
+}
+
+func (routes apiRoutes) handleRenameProjectFolder(w http.ResponseWriter, r *http.Request) {
+	projectID := strings.TrimSpace(chi.URLParam(r, "projectId"))
+	if projectID == "" {
+		WriteError(w, http.StatusBadRequest, RequestIDFromContext(r.Context()), "invalid_request", "Project ID is required.")
+		return
+	}
+
+	payload, ok := decodeRenameProjectFolderRequest(w, r)
+	if !ok {
+		return
+	}
+
+	payload.FolderID = strings.TrimSpace(payload.FolderID)
+	payload.Name = strings.TrimSpace(payload.Name)
+	if payload.FolderID == "" {
+		WriteError(w, http.StatusBadRequest, RequestIDFromContext(r.Context()), "invalid_request", "Folder ID is required.")
+		return
+	}
+	if payload.Name == "" {
+		WriteError(w, http.StatusBadRequest, RequestIDFromContext(r.Context()), "invalid_request", "Folder name is required.")
+		return
+	}
+
+	result, err := routes.bootstrapService().RenameProjectFolder(r.Context(), bootstrapservice.RenameProjectFolderInput{
+		ProjectID: projectID,
+		FolderID:  payload.FolderID,
+		Name:      payload.Name,
+	})
+	if err != nil {
+		routes.writeProjectFolderError(w, r, err, "rename")
+		return
+	}
+
+	WriteJSON(w, http.StatusOK, map[string]any{
+		"data": result,
+		"meta": map[string]any{
+			"resource":  "project-folder-rename",
+			"persisted": true,
+		},
+	})
+}
+
+func (routes apiRoutes) handleMoveProjectFolder(w http.ResponseWriter, r *http.Request) {
+	projectID := strings.TrimSpace(chi.URLParam(r, "projectId"))
+	if projectID == "" {
+		WriteError(w, http.StatusBadRequest, RequestIDFromContext(r.Context()), "invalid_request", "Project ID is required.")
+		return
+	}
+
+	payload, ok := decodeMoveProjectFolderRequest(w, r)
+	if !ok {
+		return
+	}
+
+	payload.FolderID = strings.TrimSpace(payload.FolderID)
+	payload.FolderNodeID = strings.TrimSpace(payload.FolderNodeID)
+	payload.ParentFolderID = strings.TrimSpace(payload.ParentFolderID)
+	payload.ParentNodeID = strings.TrimSpace(payload.ParentNodeID)
+	if payload.FolderID == "" {
+		WriteError(w, http.StatusBadRequest, RequestIDFromContext(r.Context()), "invalid_request", "Folder ID is required.")
+		return
+	}
+
+	result, err := routes.bootstrapService().MoveProjectFolder(r.Context(), bootstrapservice.MoveProjectFolderInput{
+		ProjectID:      projectID,
+		FolderID:       payload.FolderID,
+		FolderNodeID:   payload.FolderNodeID,
+		ParentFolderID: payload.ParentFolderID,
+		ParentNodeID:   payload.ParentNodeID,
+		TargetIndex:    payload.TargetIndex,
+	})
+	if err != nil {
+		routes.writeProjectFolderError(w, r, err, "move")
+		return
+	}
+
+	WriteJSON(w, http.StatusOK, map[string]any{
+		"data": result,
+		"meta": map[string]any{
+			"resource":  "project-folder-move",
+			"persisted": true,
+		},
+	})
+}
+
+func (routes apiRoutes) handleProjectTreeFolders(w http.ResponseWriter, r *http.Request) {
+	projectID := strings.TrimSpace(chi.URLParam(r, "projectId"))
+	if projectID == "" {
+		WriteError(w, http.StatusBadRequest, RequestIDFromContext(r.Context()), "invalid_request", "Project ID is required.")
+		return
+	}
+
+	folders, err := routes.bootstrapService().GetProjectTreeFolders(r.Context(), projectID)
+	if err != nil {
+		routes.writeProjectFolderError(w, r, err, "load")
+		return
+	}
+
+	WriteJSON(w, http.StatusOK, map[string]any{
+		"data": map[string]any{
+			"projectId": projectID,
+			"folders":   folders,
+		},
+		"meta": map[string]any{
+			"resource": "project-tree-folders",
+		},
+	})
+}
+
+func (routes apiRoutes) handleCreateProjectTreeFolder(w http.ResponseWriter, r *http.Request) {
+	projectID := strings.TrimSpace(chi.URLParam(r, "projectId"))
+	if projectID == "" {
+		WriteError(w, http.StatusBadRequest, RequestIDFromContext(r.Context()), "invalid_request", "Project ID is required.")
+		return
+	}
+
+	payload, ok := decodeProjectFolderRequest(w, r)
+	if !ok {
+		return
+	}
+
+	payload.Name = strings.TrimSpace(payload.Name)
+	payload.ParentFolderID = strings.TrimSpace(payload.ParentFolderID)
+	if payload.Name == "" {
+		WriteError(w, http.StatusBadRequest, RequestIDFromContext(r.Context()), "invalid_request", "Folder name is required.")
+		return
+	}
+
+	result, err := routes.bootstrapService().CreateProjectTreeFolder(r.Context(), bootstrapservice.CreateProjectFolderInput{
+		ProjectID:      projectID,
+		ParentFolderID: payload.ParentFolderID,
+		Name:           payload.Name,
+	})
+	if err != nil {
+		routes.writeProjectFolderError(w, r, err, "persist")
+		return
+	}
+
+	WriteJSON(w, http.StatusCreated, map[string]any{
+		"data": result,
+		"meta": map[string]any{
+			"resource":  "project-tree-folder-create",
+			"persisted": true,
+		},
+	})
+}
+
+func (routes apiRoutes) handleDeleteProjectTreeFolder(w http.ResponseWriter, r *http.Request) {
+	projectID := strings.TrimSpace(chi.URLParam(r, "projectId"))
+	if projectID == "" {
+		WriteError(w, http.StatusBadRequest, RequestIDFromContext(r.Context()), "invalid_request", "Project ID is required.")
+		return
+	}
+
+	payload := decodeDeleteProjectFolderRequest(r)
+	if strings.TrimSpace(payload.FolderID) == "" {
+		WriteError(w, http.StatusBadRequest, RequestIDFromContext(r.Context()), "invalid_request", "Folder ID is required.")
+		return
+	}
+
+	result, err := routes.bootstrapService().DeleteProjectTreeFolder(r.Context(), bootstrapservice.DeleteProjectFolderInput{
+		ProjectID: projectID,
+		FolderID:  payload.FolderID,
+	})
+	if err != nil {
+		routes.writeProjectFolderError(w, r, err, "delete")
+		return
+	}
+
+	WriteJSON(w, http.StatusOK, map[string]any{
+		"data": result,
+		"meta": map[string]any{
+			"resource":  "project-tree-folder-delete",
+			"persisted": true,
+		},
+	})
+}
+
+func (routes apiRoutes) handleRenameProjectTreeFolder(w http.ResponseWriter, r *http.Request) {
+	projectID := strings.TrimSpace(chi.URLParam(r, "projectId"))
+	if projectID == "" {
+		WriteError(w, http.StatusBadRequest, RequestIDFromContext(r.Context()), "invalid_request", "Project ID is required.")
+		return
+	}
+
+	payload, ok := decodeRenameProjectFolderRequest(w, r)
+	if !ok {
+		return
+	}
+
+	payload.FolderID = strings.TrimSpace(payload.FolderID)
+	payload.Name = strings.TrimSpace(payload.Name)
+	if payload.FolderID == "" {
+		WriteError(w, http.StatusBadRequest, RequestIDFromContext(r.Context()), "invalid_request", "Folder ID is required.")
+		return
+	}
+	if payload.Name == "" {
+		WriteError(w, http.StatusBadRequest, RequestIDFromContext(r.Context()), "invalid_request", "Folder name is required.")
+		return
+	}
+
+	result, err := routes.bootstrapService().RenameProjectTreeFolder(r.Context(), bootstrapservice.RenameProjectFolderInput{
+		ProjectID: projectID,
+		FolderID:  payload.FolderID,
+		Name:      payload.Name,
+	})
+	if err != nil {
+		routes.writeProjectFolderError(w, r, err, "rename")
+		return
+	}
+
+	WriteJSON(w, http.StatusOK, map[string]any{
+		"data": result,
+		"meta": map[string]any{
+			"resource":  "project-tree-folder-rename",
+			"persisted": true,
+		},
+	})
+}
+
+func (routes apiRoutes) handleMoveProjectTreeFolder(w http.ResponseWriter, r *http.Request) {
+	projectID := strings.TrimSpace(chi.URLParam(r, "projectId"))
+	if projectID == "" {
+		WriteError(w, http.StatusBadRequest, RequestIDFromContext(r.Context()), "invalid_request", "Project ID is required.")
+		return
+	}
+
+	payload, ok := decodeMoveProjectFolderRequest(w, r)
+	if !ok {
+		return
+	}
+
+	payload.FolderID = strings.TrimSpace(payload.FolderID)
+	payload.FolderNodeID = strings.TrimSpace(payload.FolderNodeID)
+	payload.ParentFolderID = strings.TrimSpace(payload.ParentFolderID)
+	payload.ParentNodeID = strings.TrimSpace(payload.ParentNodeID)
+	if payload.FolderID == "" {
+		WriteError(w, http.StatusBadRequest, RequestIDFromContext(r.Context()), "invalid_request", "Folder ID is required.")
+		return
+	}
+
+	result, err := routes.bootstrapService().MoveProjectTreeFolder(r.Context(), bootstrapservice.MoveProjectFolderInput{
+		ProjectID:      projectID,
+		FolderID:       payload.FolderID,
+		FolderNodeID:   payload.FolderNodeID,
+		ParentFolderID: payload.ParentFolderID,
+		ParentNodeID:   payload.ParentNodeID,
+		TargetIndex:    payload.TargetIndex,
+	})
+	if err != nil {
+		routes.writeProjectFolderError(w, r, err, "move")
+		return
+	}
+
+	WriteJSON(w, http.StatusOK, map[string]any{
+		"data": result,
+		"meta": map[string]any{
+			"resource":  "project-tree-folder-move",
+			"persisted": true,
+		},
+	})
+}
+
+func (routes apiRoutes) writeProjectFolderError(w http.ResponseWriter, r *http.Request, err error, operation string) {
 	switch {
 	case errors.Is(err, bootstrapservice.ErrProjectNotFound), errors.Is(err, bootstrapservice.ErrProjectFolderNotFound):
 		WriteError(w, http.StatusNotFound, RequestIDFromContext(r.Context()), "not_found", err.Error())
+	case errors.Is(err, bootstrapservice.ErrInvalidProjectFolderMove):
+		WriteError(w, http.StatusBadRequest, RequestIDFromContext(r.Context()), "invalid_request", err.Error())
 	default:
-		routes.cfg.Logger.Error("persist project folder", "error", err, "path", r.URL.Path)
-		message := "Failed to persist project folder."
+		routes.cfg.Logger.Error(operation+" project folder", "error", err, "path", r.URL.Path)
+		message := "Failed to " + operation + " project folder."
 		if routes.cfg.Config.IsDevelopment() {
 			message = message + " " + err.Error()
 		}
-		WriteError(w, http.StatusInternalServerError, RequestIDFromContext(r.Context()), "project_folder_persist_failed", message)
+		WriteError(w, http.StatusInternalServerError, RequestIDFromContext(r.Context()), "project_folder_"+operation+"_failed", message)
 	}
 }
 
+func decodeMoveProjectFolderRequest(w http.ResponseWriter, r *http.Request) (moveProjectFolderRequest, bool) {
+	var payload moveProjectFolderRequest
+
+	decoder := json.NewDecoder(r.Body)
+	decoder.DisallowUnknownFields()
+
+	if err := decoder.Decode(&payload); err != nil {
+		if errors.Is(err, io.EOF) {
+			WriteError(w, http.StatusBadRequest, RequestIDFromContext(r.Context()), "invalid_json", "The request body is required and must be valid JSON.")
+			return payload, false
+		}
+
+		WriteError(w, http.StatusBadRequest, RequestIDFromContext(r.Context()), "invalid_json", "The request body must be valid JSON.")
+		return payload, false
+	}
+
+	if err := decoder.Decode(&struct{}{}); !errors.Is(err, io.EOF) {
+		WriteError(w, http.StatusBadRequest, RequestIDFromContext(r.Context()), "invalid_json", "The request body must contain a single JSON object.")
+		return payload, false
+	}
+
+	return payload, true
+}
+
+func decodeDeleteProjectFolderRequest(r *http.Request) deleteProjectFolderRequest {
+	return deleteProjectFolderRequest{
+		FolderID: strings.TrimSpace(r.URL.Query().Get("folderId")),
+	}
+}
+
+func decodeRenameProjectFolderRequest(w http.ResponseWriter, r *http.Request) (renameProjectFolderRequest, bool) {
+	var payload renameProjectFolderRequest
+
+	decoder := json.NewDecoder(r.Body)
+	decoder.DisallowUnknownFields()
+
+	if err := decoder.Decode(&payload); err != nil {
+		if errors.Is(err, io.EOF) {
+			WriteError(w, http.StatusBadRequest, RequestIDFromContext(r.Context()), "invalid_json", "The request body is required and must be valid JSON.")
+			return payload, false
+		}
+
+		WriteError(w, http.StatusBadRequest, RequestIDFromContext(r.Context()), "invalid_json", "The request body must be valid JSON.")
+		return payload, false
+	}
+
+	if err := decoder.Decode(&struct{}{}); !errors.Is(err, io.EOF) {
+		WriteError(w, http.StatusBadRequest, RequestIDFromContext(r.Context()), "invalid_json", "The request body must contain a single JSON object.")
+		return payload, false
+	}
+
+	return payload, true
+}
+
 func decodeProjectFolderRequest(w http.ResponseWriter, r *http.Request) (createProjectFolderRequest, bool) {
 	var payload createProjectFolderRequest
 

Backend/internal/httpx/api_routes.go

@@ -36,6 +36,14 @@ func (routes apiRoutes) Register(router chi.Router) {
 		apiRouter.Route("/projects/{projectId}", func(projectRouter chi.Router) {
 			projectRouter.Get("/folders", routes.handleProjectFolders)
 			projectRouter.Post("/folders", routes.handleCreateProjectFolder)
+			projectRouter.Patch("/folders", routes.handleRenameProjectFolder)
+			projectRouter.Patch("/folders/move", routes.handleMoveProjectFolder)
+			projectRouter.Delete("/folders", routes.handleDeleteProjectFolder)
+			projectRouter.Get("/tree/folders", routes.handleProjectTreeFolders)
+			projectRouter.Post("/tree/folders", routes.handleCreateProjectTreeFolder)
+			projectRouter.Patch("/tree/folders", routes.handleRenameProjectTreeFolder)
+			projectRouter.Patch("/tree/folders/move", routes.handleMoveProjectTreeFolder)
+			projectRouter.Delete("/tree/folders", routes.handleDeleteProjectTreeFolder)
 		})
 
 		if routes.cfg.Config.IsDevelopment() {

Backend/internal/posixproj/projector.go

@@ -411,7 +411,7 @@ func classifyPath(relPath string, isDir bool) (logicalType, fileRole string) {
 				return "hierarchy_folder", ""
 			}
 			if hasTreeAncestor && strings.HasPrefix(name, "folder-") {
-				return "folder", ""
+				return "hierarchy_folder", ""
 			}
 			if hasTreeAncestor && strings.HasPrefix(name, "item-") {
 				return "item", ""
@@ -425,7 +425,7 @@ func classifyPath(relPath string, isDir bool) (logicalType, fileRole string) {
 				return "item", fileRole
 			}
 			if strings.HasPrefix(parentName, "folder-") {
-				return "folder", fileRole
+				return "hierarchy_folder", fileRole
 			}
 		}
 		return "project", fileRole

Backend/internal/posixproj/projector_test.go

@@ -16,6 +16,7 @@ func TestScanRootBuildsProjectedNodesFromBootstrapShape(t *testing.T) {
 	mustMkdirAll(t, filepath.Join(root, "projects", "project-primary-project", "children", "folder-design", "children", "project-web", "children"))
 	mustMkdirAll(t, filepath.Join(root, "projects", "project-primary-project", "children", "folder-design", "children", "project-web", "tree"))
 	mustMkdirAll(t, filepath.Join(root, "projects", "project-primary-project", "tree"))
+	mustMkdirAll(t, filepath.Join(root, "projects", "project-primary-project", "tree", "folder-docs", "children"))
 	mustMkdirAll(t, filepath.Join(root, "projects", "project-primary-project", "tree", "folder-docs", "item-roadmap"))
 	mustMkdirAll(t, filepath.Join(root, "users", "personals"))
 
@@ -185,10 +186,15 @@ func TestScanRootBuildsProjectedNodesFromBootstrapShape(t *testing.T) {
 	}
 
 	treeFolder := index["projects/project-primary-project/tree/folder-docs"]
-	if treeFolder.LogicalType != "folder" || treeFolder.ProjectSlug != "primary-project" {
+	if treeFolder.LogicalType != "hierarchy_folder" || treeFolder.ProjectSlug != "primary-project" {
 		t.Fatalf("unexpected tree folder node: %#v", treeFolder)
 	}
 
+	treeFolderACL := index["projects/project-primary-project/tree/folder-docs/folder.json"]
+	if treeFolderACL.LogicalType != "hierarchy_folder" || treeFolderACL.FileRole != "folder" {
+		t.Fatalf("unexpected tree folder file classification: %#v", treeFolderACL)
+	}
+
 	treeItem := index["projects/project-primary-project/tree/folder-docs/item-roadmap/item.json"]
 	if treeItem.LogicalType != "item" || treeItem.FileRole != "item" {
 		t.Fatalf("unexpected tree item classification: %#v", treeItem)

Frontend/src/components/shell/ProjectSelector/ProjectSelector.module.scss

@@ -1,3 +1,5 @@
+@use "../shared/tree-nav" as treeNav;
+
 .root {
   display: grid;
   --project-drawer-gap: var(--space-3);
@@ -191,12 +193,9 @@
 }
 
 .treeSectionLabel {
-  @include text-caption;
+	@include treeNav.section-label;
   margin: 0;
   padding: 0 var(--space-3);
-  color: var(--color-text-subtle);
-  text-transform: uppercase;
-  letter-spacing: 0.04em;
 }
 
 .treeSectionHeader {
@@ -248,133 +247,72 @@
 }
 
 .treeList {
-  list-style: none;
-  display: grid;
-  gap: var(--space-1);
-  padding: 0;
+	@include treeNav.tree-list;
 }
 
 .treeEmptySlot {
-	min-height: calc(var(--control-size-lg) - var(--space-2));
-	padding-left: calc(var(--space-3) + (var(--tree-depth, 0) * var(--space-4)));
-	border-radius: var(--radius-lg);
-	border: 1px dashed color-mix(in srgb, var(--color-border) 38%, transparent);
-	opacity: 0.35;
+	@include treeNav.empty-slot;
 }
 
 .treeInputRow {
-	width: 100%;
-	min-width: 0;
-	display: grid;
-	grid-template-columns: auto minmax(0, 1fr);
-	align-items: center;
-	gap: var(--space-2);
-	min-height: calc(var(--control-size-lg) - var(--space-2));
-	padding: var(--space-2) var(--space-3);
-	padding-left: calc(var(--space-3) + (var(--tree-depth, 0) * var(--space-4)));
-	border: 1px solid color-mix(in srgb, var(--color-border) 42%, transparent);
-	border-radius: var(--radius-lg);
-	background: color-mix(in srgb, var(--color-surface) 94%, transparent);
+	@include treeNav.input-row;
 }
 
 .treeInput {
-	width: 100%;
-	min-width: 0;
-	border: 0;
-	background: transparent;
-	color: var(--color-text);
-	font: inherit;
-	outline: none;
-}
-
-.treeInput::placeholder {
-	color: var(--color-text-muted);
+	@include treeNav.input;
 }
 
 .treeItem {
-  width: 100%;
-  min-width: 0;
-  display: grid;
-  grid-template-columns: auto auto minmax(0, 1fr) auto;
-  align-items: center;
-  gap: var(--space-2);
-  min-height: calc(var(--control-size-lg) - var(--space-2));
-  padding: var(--space-2) var(--space-3);
-  padding-left: calc(var(--space-3) + (var(--tree-depth, 0) * var(--space-4)));
-  border: 1px solid transparent;
-  border-radius: var(--radius-lg);
-  background: transparent;
-  color: var(--color-text-muted);
-  transition:
-    background 160ms var(--easing-standard),
-    color 160ms var(--easing-standard),
-    border-color 160ms var(--easing-standard),
-    box-shadow 160ms var(--easing-standard),
-    transform 180ms var(--easing-standard);
-  text-align: left;
+	@include treeNav.item;
 }
 
 .treeItem:hover,
 .treeItem:focus-visible {
-  background: color-mix(in srgb, var(--color-surface-hover) 80%, var(--color-accent-soft) 20%);
-  color: var(--color-text);
-  box-shadow: inset 0 1px 0 color-mix(in srgb, white 4%, transparent);
+	@include treeNav.item-hover;
 }
 
 .treeItemFolder {
-  color: var(--color-text);
+	@include treeNav.item-folder;
 }
 
 .treeItemDragging {
-	opacity: 0.45;
-	transform: scale(0.985);
-	box-shadow: none;
+	@include treeNav.item-dragging;
 }
 
 .treeItemDropBefore {
-	box-shadow: inset 0 2px 0 color-mix(in srgb, var(--color-accent-strong) 78%, transparent);
+	@include treeNav.item-drop-before;
 }
 
 .treeItemDropAfter {
-	box-shadow: inset 0 -2px 0 color-mix(in srgb, var(--color-accent-strong) 78%, transparent);
+	@include treeNav.item-drop-after;
 }
 
 .treeItemDropInside {
-	border-color: color-mix(in srgb, var(--color-accent-strong) 55%, transparent);
-	background: color-mix(in srgb, var(--color-accent-soft) 36%, var(--color-surface));
-	color: var(--color-text);
-	box-shadow: inset 0 1px 0 color-mix(in srgb, white 4%, transparent);
+	@include treeNav.item-drop-inside;
 }
 
 .folderChevron {
-  color: var(--color-text-muted);
-  transition: transform 160ms var(--easing-standard);
+	@include treeNav.folder-chevron;
 }
 
 .folderChevronOpen {
-  transform: rotate(90deg);
+	@include treeNav.folder-chevron-open;
 }
 
 .treeItemActive {
-  border-color: var(--color-border);
-  background: var(--color-surface);
-  color: var(--color-text);
-  box-shadow: inset 0 1px 0 color-mix(in srgb, white 4%, transparent);
+	@include treeNav.item-active;
 }
 
 .icon {
-  color: inherit;
-  opacity: 0.85;
+	@include treeNav.icon;
 }
 
 .label {
-  @include text-label;
-  min-width: 0;
+	@include treeNav.label;
 }
 
 .itemMeta {
-  @include text-caption;
-  color: var(--color-text-muted);
+	@include treeNav.item-meta;
 }
 
 @media (max-width: 720px) {

Frontend/src/components/shell/ProjectSelector/ProjectSelector.tsx

@@ -5,6 +5,17 @@ import { ChevronDown, ChevronRight, Folder, LayoutGrid, ListCollapse, UnfoldVert
 import { ProjectContextMenu } from "../ProjectContextMenu/ProjectContextMenu";
 import { useAppShellData } from "../data/app-shell.context";
 import { resolveAPIBase } from "../../../lib/api";
+import {
+	collectBranchNodeIds,
+	findTreeNodeDepth,
+	findTreeNodeLocation,
+	getPointerRelativeY,
+	isUuidString,
+	moveTreeNode,
+	resolveTreeDropTarget,
+	type NavTreeAdapter,
+	type NavTreeDropTarget,
+} from "../shared/navTreeDnd";
 import {
 	createProjectFolderTarget,
 	createProjectSurfaceTarget,
@@ -25,6 +36,7 @@ type ProjectSelectorProps = {
 type ProjectFolderNode = {
 	kind: "folder";
 	id: string;
+	path: string;
 	label: string;
 	meta?: string;
 	children: ProjectTreeNode[];
@@ -39,6 +51,7 @@ type ProjectTreeNode = ProjectFolderNode | ProjectLeafNode;
 
 type PersistedProjectFolderRecord = {
 	id: string;
+	path: string;
 	label: string;
 	children: PersistedProjectFolderRecord[];
 };
@@ -46,6 +59,10 @@ type PersistedProjectFolderRecord = {
 type ProjectFoldersResponse = {
 	data?: {
 		folders?: PersistedProjectFolderRecord[];
+		renamedFolder?: PersistedProjectFolderRecord;
+		movedFolder?: PersistedProjectFolderRecord;
+		previousFolderId?: string;
+		previousFolderPath?: string;
 	};
 	error?: string;
 	message?: string;
@@ -56,24 +73,18 @@ type PendingProjectFolderDraft = {
 	depth: number;
 };
 
-type ProjectDragTarget = {
-	parentId: string | null;
-	index: number;
-	intent: "before" | "after" | "inside";
-	targetNodeId?: string;
+type PendingProjectFolderRename = {
+	folderId: string;
+	depth: number;
 };
 
+type ProjectDragTarget = NavTreeDropTarget;
+
 type ProjectDragState = {
 	draggedNodeId: string;
 	dropTarget: ProjectDragTarget | null;
 };
 
-type ProjectNodeLocation = {
-	parentId: string | null;
-	index: number;
-	node: ProjectTreeNode;
-};
-
 const LONG_PRESS_MS = 320;
 
 const getProjectTreeNodeId = (node: ProjectTreeNode): string =>
@@ -83,6 +94,7 @@ const buildPersistedFolderNodes = (folders: readonly PersistedProjectFolderRecor
 	folders.map((folder) => ({
 		kind: "folder",
 		id: folder.id,
+		path: folder.path,
 		label: folder.label,
 		children: buildPersistedFolderNodes(folder.children ?? []),
 	}));
@@ -98,198 +110,20 @@ const buildProjectTree = (
 	...buildPersistedFolderNodes(folders),
 ];
 
-const collectProjectFolderIds = (nodes: readonly ProjectTreeNode[]): string[] => {
-	const ids: string[] = [];
-
-	for (const node of nodes) {
-		if (node.kind !== "folder") {
-			continue;
-		}
-
-		ids.push(node.id);
-		ids.push(...collectProjectFolderIds(node.children));
-	}
-
-	return ids;
-};
-
 const readPersistedFolders = (body: ProjectFoldersResponse): PersistedProjectFolderRecord[] =>
 	Array.isArray(body.data?.folders) ? body.data.folders : [];
 
-const cloneProjectTreeNode = (node: ProjectTreeNode): ProjectTreeNode => {
-	if (node.kind === "project") {
-		return {
-			kind: "project",
-			item: { ...node.item },
-		};
-	}
-
-	return {
-		kind: "folder",
-		id: node.id,
-		label: node.label,
-		meta: node.meta,
-		children: node.children.map(cloneProjectTreeNode),
-	};
-};
-
-const findProjectNodeLocation = (
-	nodes: readonly ProjectTreeNode[],
-	nodeId: string,
-	parentId: string | null = null,
-): ProjectNodeLocation | null => {
-	for (let index = 0; index < nodes.length; index += 1) {
-		const node = nodes[index];
-
-		if (getProjectTreeNodeId(node) === nodeId) {
-			return { parentId, index, node };
-		}
-
-		if (node.kind === "folder") {
-			const nestedLocation = findProjectNodeLocation(node.children, nodeId, node.id);
-
-			if (nestedLocation) {
-				return nestedLocation;
-			}
-		}
-	}
-
-	return null;
-};
-
-const findProjectNodeDepth = (nodes: readonly ProjectTreeNode[], nodeId: string, depth = 0): number | null => {
-	for (const node of nodes) {
-		if (getProjectTreeNodeId(node) === nodeId) {
-			return depth;
-		}
-
-		if (node.kind === "folder") {
-			const nestedDepth = findProjectNodeDepth(node.children, nodeId, depth + 1);
-
-			if (nestedDepth !== null) {
-				return nestedDepth;
-			}
-		}
-	}
-
-	return null;
-};
-
-const projectTreeContainsNode = (nodes: readonly ProjectTreeNode[], nodeId: string): boolean => {
-	for (const node of nodes) {
-		if (getProjectTreeNodeId(node) === nodeId) {
-			return true;
-		}
-
-		if (node.kind === "folder" && projectTreeContainsNode(node.children, nodeId)) {
-			return true;
-		}
-	}
-
-	return false;
-};
-
-const removeProjectTreeNode = (
-	nodes: readonly ProjectTreeNode[],
-	nodeId: string,
-): { nodes: ProjectTreeNode[]; removed: ProjectTreeNode | null } => {
-	const nextNodes: ProjectTreeNode[] = [];
-	let removed: ProjectTreeNode | null = null;
-
-	for (const node of nodes) {
-		if (getProjectTreeNodeId(node) === nodeId) {
-			removed = node;
-			continue;
-		}
-
-		if (node.kind === "folder") {
-			const result = removeProjectTreeNode(node.children, nodeId);
-
-			if (result.removed) {
-				removed = result.removed;
-				nextNodes.push({
-					...node,
-					children: result.nodes,
-				});
-				continue;
-			}
-		}
-
-		nextNodes.push(node);
-	}
-
-	return { nodes: nextNodes, removed };
-};
-
-const insertProjectTreeNode = (
-	nodes: readonly ProjectTreeNode[],
-	parentId: string | null,
-	index: number,
-	nodeToInsert: ProjectTreeNode,
-): ProjectTreeNode[] => {
-	if (parentId === null) {
-		const nextNodes = [...nodes];
-		nextNodes.splice(Math.max(0, Math.min(index, nextNodes.length)), 0, nodeToInsert);
-		return nextNodes;
-	}
-
-	return nodes.map((node) => {
-		if (node.kind !== "folder") {
-			return node;
-		}
-
-		if (node.id === parentId) {
-			const nextChildren = [...node.children];
-			nextChildren.splice(Math.max(0, Math.min(index, nextChildren.length)), 0, nodeToInsert);
-			return {
+const projectTreeAdapter: NavTreeAdapter<ProjectTreeNode> = {
+	getNodeId: getProjectTreeNodeId,
+	isBranchNode: (node) => node.kind === "folder",
+	getChildren: (node) => (node.kind === "folder" ? node.children : []),
+	withChildren: (node, children) =>
+		node.kind === "folder"
+			? {
 				...node,
-				children: nextChildren,
-			};
-		}
-
-		return {
-			...node,
-			children: insertProjectTreeNode(node.children, parentId, index, nodeToInsert),
-		};
-	});
-};
-
-const moveProjectTreeNode = (
-	nodes: readonly ProjectTreeNode[],
-	draggedNodeId: string,
-	dropTarget: ProjectDragTarget,
-): ProjectTreeNode[] => {
-	const location = findProjectNodeLocation(nodes, draggedNodeId);
-
-	if (!location) {
-		return [...nodes];
-	}
-
-	if (
-		location.node.kind === "folder" &&
-		dropTarget.parentId !== null &&
-		(projectTreeContainsNode(location.node.children, dropTarget.parentId) || dropTarget.parentId === location.node.id)
-	) {
-		return [...nodes];
-	}
-
-	let normalizedIndex = dropTarget.index;
-
-	if (dropTarget.parentId === location.parentId && dropTarget.index > location.index) {
-		normalizedIndex -= 1;
-	}
-
-	if (dropTarget.parentId === location.parentId && normalizedIndex === location.index) {
-		return [...nodes];
-	}
-
-	const removalResult = removeProjectTreeNode(nodes, draggedNodeId);
-
-	if (!removalResult.removed) {
-		return [...nodes];
-	}
-
-	return insertProjectTreeNode(removalResult.nodes, dropTarget.parentId, normalizedIndex, removalResult.removed);
+				children: [...children],
+			}
+			: node,
 };
 
 const ProjectFolderDraftRow = (props: {
@@ -351,6 +185,11 @@ const ProjectFolderBranch = (props: {
 	onPendingFolderNameChange: (value: string) => void;
 	onSubmitPendingFolder: () => void;
 	onCancelPendingFolder: () => void;
+	pendingFolderRename: PendingProjectFolderRename | null;
+	pendingFolderRenameName: string;
+	onPendingFolderRenameChange: (value: string) => void;
+	onSubmitPendingFolderRename: () => void;
+	onCancelPendingFolderRename: () => void;
 	dragState: ProjectDragState | null;
 	isTreeClickSuppressed: () => boolean;
 }): JSX.Element => (
@@ -375,51 +214,65 @@ const ProjectFolderBranch = (props: {
 
 				if (node.kind === "folder") {
 					const isCollapsed = (): boolean => props.isFolderCollapsed(node.id);
+					const isRenaming = (): boolean => props.pendingFolderRename?.folderId === node.id;
 
 					return (
 						<li>
-							<button
-								type="button"
-								classList={{
-									[styles.treeItem]: true,
-									[styles.treeItemFolder]: true,
-									[styles.treeItemDragging]: isDraggedNode(),
-									[styles.treeItemDropBefore]: dropIntent() === "before",
-								[styles.treeItemDropAfter]: dropIntent() === "after",
-								[styles.treeItemDropInside]: dropIntent() === "inside",
-							}}
-							style={{ "--tree-depth": String(props.depth) }}
-							aria-expanded={!isCollapsed()}
-							onClick={() => {
-								if (props.dragState || props.isTreeClickSuppressed()) {
-									return;
-								}
+							<Show
+								when={isRenaming()}
+								fallback={
+									<button
+										type="button"
+										classList={{
+											[styles.treeItem]: true,
+											[styles.treeItemFolder]: true,
+											[styles.treeItemDragging]: isDraggedNode(),
+											[styles.treeItemDropBefore]: dropIntent() === "before",
+											[styles.treeItemDropAfter]: dropIntent() === "after",
+											[styles.treeItemDropInside]: dropIntent() === "inside",
+										}}
+										style={{ "--tree-depth": String(props.depth) }}
+										aria-expanded={!isCollapsed()}
+										onClick={() => {
+											if (props.dragState || props.isTreeClickSuppressed()) {
+												return;
+											}
 
-								props.onToggleFolder(node.id);
-							}}
-								onContextMenu={(event): void => props.onOpenFolderMenu(event, node)}
-								onPointerDown={(event): void => props.onNodePointerDown(event, node.id)}
-								onPointerMove={(event): void =>
-									props.onNodePointerMove(event, props.parentId, indexAccessor(), node)
-								}
-								onPointerEnter={(event): void =>
-									props.onNodePointerMove(event, props.parentId, indexAccessor(), node)
+											props.onToggleFolder(node.id);
+										}}
+										onContextMenu={(event): void => props.onOpenFolderMenu(event, node)}
+										onPointerDown={(event): void => props.onNodePointerDown(event, node.id)}
+										onPointerMove={(event): void =>
+											props.onNodePointerMove(event, props.parentId, indexAccessor(), node)
+										}
+										onPointerEnter={(event): void =>
+											props.onNodePointerMove(event, props.parentId, indexAccessor(), node)
+										}
+									>
+										<ChevronRight
+											classList={{
+												[styles.folderChevron]: true,
+												[styles.folderChevronOpen]: !isCollapsed(),
+											}}
+											size={16}
+											strokeWidth={2}
+										/>
+										<Folder class={styles.icon} size={18} strokeWidth={2} />
+										<span class={styles.label}>{node.label}</span>
+										<Show when={node.meta}>
+											<span class={styles.itemMeta}>{node.meta}</span>
+										</Show>
+									</button>
 								}
 							>
-								<ChevronRight
-									classList={{
-										[styles.folderChevron]: true,
-										[styles.folderChevronOpen]: !isCollapsed(),
-									}}
-									size={16}
-									strokeWidth={2}
+								<ProjectFolderDraftRow
+									depth={props.pendingFolderRename?.depth ?? props.depth}
+									value={props.pendingFolderRenameName}
+									onInput={props.onPendingFolderRenameChange}
+									onSubmit={props.onSubmitPendingFolderRename}
+									onCancel={props.onCancelPendingFolderRename}
 								/>
-								<Folder class={styles.icon} size={18} strokeWidth={2} />
-								<span class={styles.label}>{node.label}</span>
-								<Show when={node.meta}>
-									<span class={styles.itemMeta}>{node.meta}</span>
-								</Show>
-							</button>
+							</Show>
 
 							<Show when={!isCollapsed() && ((node.children?.length ?? 0) > 0 || props.pendingFolderDraft?.parentId === node.id)}>
 								<ProjectFolderBranch
@@ -439,6 +292,11 @@ const ProjectFolderBranch = (props: {
 									onPendingFolderNameChange={props.onPendingFolderNameChange}
 									onSubmitPendingFolder={props.onSubmitPendingFolder}
 									onCancelPendingFolder={props.onCancelPendingFolder}
+									pendingFolderRename={props.pendingFolderRename}
+									pendingFolderRenameName={props.pendingFolderRenameName}
+									onPendingFolderRenameChange={props.onPendingFolderRenameChange}
+									onSubmitPendingFolderRename={props.onSubmitPendingFolderRename}
+									onCancelPendingFolderRename={props.onCancelPendingFolderRename}
 									dragState={props.dragState}
 									isTreeClickSuppressed={props.isTreeClickSuppressed}
 								/>
@@ -509,6 +367,8 @@ export const ProjectSelector = (props: ProjectSelectorProps): JSX.Element => {
 	);
 	const [pendingFolderDraft, setPendingFolderDraft] = createSignal<PendingProjectFolderDraft | null>(null);
 	const [pendingFolderName, setPendingFolderName] = createSignal("");
+	const [pendingFolderRename, setPendingFolderRename] = createSignal<PendingProjectFolderRename | null>(null);
+	const [pendingFolderRenameName, setPendingFolderRenameName] = createSignal("");
 	const [dragState, setDragState] = createSignal<ProjectDragState | null>(null);
 	const [suppressNextTreeClick, setSuppressNextTreeClick] = createSignal(false);
 	let rootRef: HTMLDivElement | undefined;
@@ -550,7 +410,7 @@ export const ProjectSelector = (props: ProjectSelectorProps): JSX.Element => {
 
 	const syncProjectTree = (): void => {
 		const nextTree = buildProjectTree(appShellData.projectItems(), persistedFolders());
-		const availableFolderIds = new Set(collectProjectFolderIds(nextTree));
+		const availableFolderIds = new Set(collectBranchNodeIds(nextTree, projectTreeAdapter));
 
 		setProjectTreeNodes(nextTree);
 		setCollapsedFolderIds((current) => current.filter((folderId) => availableFolderIds.has(folderId)));
@@ -560,10 +420,12 @@ export const ProjectSelector = (props: ProjectSelectorProps): JSX.Element => {
 		setCollapsedFolderIds([]);
 		setPendingFolderDraft(null);
 		setPendingFolderName("");
+		setPendingFolderRename(null);
+		setPendingFolderRenameName("");
 		setDragState(null);
 	};
 
-	const folderIds = (): string[] => collectProjectFolderIds(projectTreeNodes());
+	const folderIds = (): string[] => collectBranchNodeIds(projectTreeNodes(), projectTreeAdapter);
 
 	const expandAllFolders = (): void => {
 		setCollapsedFolderIds([]);
@@ -599,6 +461,11 @@ export const ProjectSelector = (props: ProjectSelectorProps): JSX.Element => {
 			return;
 		}
 
+		if (!isUuidString(projectId)) {
+			setPersistedFolders([]);
+			return;
+		}
+
 		try {
 			const response = await fetch(`${resolveAPIBase()}/projects/${projectId}/folders`, {
 				headers: {
@@ -712,9 +579,48 @@ export const ProjectSelector = (props: ProjectSelectorProps): JSX.Element => {
 			}
 
 			suppressTreeClickTemporarily();
-			setProjectTreeNodes((current) =>
-				moveProjectTreeNode(current, nextDragState.draggedNodeId, nextDragState.dropTarget as ProjectDragTarget),
-			);
+
+			const currentNodes = projectTreeNodes();
+			const draggedLocation = findTreeNodeLocation(currentNodes, nextDragState.draggedNodeId, projectTreeAdapter);
+			const canPersistMove = isUuidString(selectedProject().id);
+			const draggedFolderPath = draggedLocation?.node.kind === "folder" ? draggedLocation.node.path : null;
+			const previewNodes = moveTreeNode(currentNodes, nextDragState.draggedNodeId, nextDragState.dropTarget as ProjectDragTarget, projectTreeAdapter);
+			const previewLocation = findTreeNodeLocation(previewNodes, nextDragState.draggedNodeId, projectTreeAdapter);
+			const persistedParentLocation = previewLocation?.parentId
+				? findTreeNodeLocation(previewNodes, previewLocation.parentId, projectTreeAdapter)
+				: null;
+			const persistedParentFolderPath =
+				persistedParentLocation?.node.kind === "folder" ? persistedParentLocation.node.path : null;
+			const previewSiblings = previewLocation?.parentId
+				? persistedParentLocation?.node.kind === "folder"
+					? persistedParentLocation.node.children
+					: []
+				: previewNodes;
+			const targetIndex = previewLocation
+				? previewSiblings
+					.slice(0, previewLocation.index)
+					.filter((node) => node.kind === "folder").length
+				: 0;
+
+			if (
+				canPersistMove &&
+				draggedLocation?.node.kind === "folder" &&
+				draggedFolderPath &&
+				(!previewLocation?.parentId || persistedParentLocation?.node.kind === "folder")
+			) {
+				void movePersistedFolder(
+					draggedFolderPath,
+					persistedParentFolderPath,
+					draggedLocation.node.id,
+					persistedParentLocation?.node.kind === "folder" ? persistedParentLocation.node.id : null,
+					targetIndex,
+				);
+			} else {
+				setProjectTreeNodes((current) =>
+					moveTreeNode(current, nextDragState.draggedNodeId, nextDragState.dropTarget as ProjectDragTarget, projectTreeAdapter),
+				);
+			}
+
 			setDragState(null);
 		};
 
@@ -765,7 +671,7 @@ export const ProjectSelector = (props: ProjectSelectorProps): JSX.Element => {
 	};
 
 	const selectProject = (projectId: string): void => {
-		const location = findProjectNodeLocation(projectTreeNodes(), projectId);
+		const location = findTreeNodeLocation(projectTreeNodes(), projectId, projectTreeAdapter);
 
 		if (!location || location.node.kind !== "project") {
 			return;
@@ -780,13 +686,28 @@ export const ProjectSelector = (props: ProjectSelectorProps): JSX.Element => {
 			setCollapsedFolderIds((current) => current.filter((id) => id !== parentId));
 		}
 
+		setPendingFolderRename(null);
+		setPendingFolderRenameName("");
 		setPendingFolderName("");
 		setPendingFolderDraft({ parentId, depth });
 	};
 
+	const beginFolderRename = (folderId: string, label: string, depth: number): void => {
+		setPendingFolderDraft(null);
+		setPendingFolderName("");
+		setPendingFolderRename({ folderId, depth });
+		setPendingFolderRenameName(label);
+	};
+
+	const resolveFolderPath = (folderId: string): string | null => {
+		const location = findTreeNodeLocation(projectTreeNodes(), folderId, projectTreeAdapter);
+		return location && location.node.kind === "folder" ? location.node.path : null;
+	};
+
 	const submitPendingFolder = async (): Promise<void> => {
 		const name = pendingFolderName().trim();
 		const draft = pendingFolderDraft();
+		const projectId = selectedProject().id;
 
 		if (!draft) {
 			return;
@@ -798,8 +719,19 @@ export const ProjectSelector = (props: ProjectSelectorProps): JSX.Element => {
 			return;
 		}
 
+		if (!isUuidString(projectId)) {
+			cancelPendingFolder();
+			return;
+		}
+
+		const parentFolderPath = draft.parentId ? resolveFolderPath(draft.parentId) : null;
+		if (draft.parentId && !parentFolderPath) {
+			cancelPendingFolder();
+			return;
+		}
+
 		try {
-			const response = await fetch(`${resolveAPIBase()}/projects/${selectedProject().id}/folders`, {
+			const response = await fetch(`${resolveAPIBase()}/projects/${projectId}/folders`, {
 				method: "POST",
 				headers: {
 					Accept: "application/json",
@@ -807,7 +739,7 @@ export const ProjectSelector = (props: ProjectSelectorProps): JSX.Element => {
 				},
 				body: JSON.stringify({
 					name,
-					parentFolderId: draft.parentId,
+					parentFolderId: parentFolderPath,
 				}),
 			});
 
@@ -825,28 +757,173 @@ export const ProjectSelector = (props: ProjectSelectorProps): JSX.Element => {
 		}
 	};
 
+	const deletePersistedFolder = async (folderId: string): Promise<void> => {
+		const projectId = selectedProject().id;
+		if (!folderId || !isUuidString(projectId)) {
+			return;
+		}
+
+		const folderPath = resolveFolderPath(folderId);
+		if (!folderPath) {
+			return;
+		}
+
+		try {
+			const response = await fetch(
+				`${resolveAPIBase()}/projects/${projectId}/folders?folderId=${encodeURIComponent(folderPath)}`,
+				{
+					method: "DELETE",
+					headers: {
+						Accept: "application/json",
+					},
+				},
+			);
+
+			const body = (await response.json()) as ProjectFoldersResponse;
+
+			if (!response.ok) {
+				throw new Error(body.message || "Failed to delete project folder.");
+			}
+
+			setPersistedFolders(readPersistedFolders(body));
+			setCollapsedFolderIds((current) => current.filter((id) => id !== folderId));
+		} catch (error) {
+			console.error(error);
+		}
+	};
+
+	const movePersistedFolder = async (
+		folderPath: string,
+		parentFolderPath: string | null,
+		folderNodeId: string,
+		parentNodeId: string | null,
+		targetIndex: number,
+	): Promise<void> => {
+		const projectId = selectedProject().id;
+		if (!folderPath || !folderNodeId || !isUuidString(projectId)) {
+			return;
+		}
+
+		try {
+			const response = await fetch(`${resolveAPIBase()}/projects/${projectId}/folders/move`, {
+				method: "PATCH",
+				headers: {
+					Accept: "application/json",
+					"Content-Type": "application/json",
+				},
+				body: JSON.stringify({
+					folderId: folderPath,
+					folderNodeId,
+					parentFolderId: parentFolderPath,
+					parentNodeId,
+					targetIndex,
+				}),
+			});
+
+			const body = (await response.json()) as ProjectFoldersResponse;
+
+			if (!response.ok) {
+				throw new Error(body.message || "Failed to move project folder.");
+			}
+
+			setPersistedFolders(readPersistedFolders(body));
+		} catch (error) {
+			console.error(error);
+		}
+	};
+
+	const submitPendingFolderRename = async (): Promise<void> => {
+		const draft = pendingFolderRename();
+		const name = pendingFolderRenameName().trim();
+		const projectId = selectedProject().id;
+
+		if (!draft) {
+			return;
+		}
+
+		if (!name) {
+			setPendingFolderRename(null);
+			setPendingFolderRenameName("");
+			return;
+		}
+
+		if (!isUuidString(projectId)) {
+			cancelPendingFolderRename();
+			return;
+		}
+
+		const folderPath = resolveFolderPath(draft.folderId);
+		if (!folderPath) {
+			cancelPendingFolderRename();
+			return;
+		}
+
+		try {
+			const response = await fetch(`${resolveAPIBase()}/projects/${projectId}/folders`, {
+				method: "PATCH",
+				headers: {
+					Accept: "application/json",
+					"Content-Type": "application/json",
+				},
+				body: JSON.stringify({
+					folderId: folderPath,
+					name,
+				}),
+			});
+
+			const body = (await response.json()) as ProjectFoldersResponse;
+
+			if (!response.ok) {
+				throw new Error(body.message || "Failed to rename project folder.");
+			}
+
+			setPersistedFolders(readPersistedFolders(body));
+			setPendingFolderRename(null);
+			setPendingFolderRenameName("");
+		} catch (error) {
+			console.error(error);
+		}
+	};
+
 	const cancelPendingFolder = (): void => {
 		setPendingFolderDraft(null);
 		setPendingFolderName("");
 	};
 
-	const handleContextActionSelect = (action: { id: string; label: string }, target: ProjectMenuTarget): void => {
-		if (action.id !== "new-folder") {
-			return;
-		}
+	const cancelPendingFolderRename = (): void => {
+		setPendingFolderRename(null);
+		setPendingFolderRenameName("");
+	};
 
-		switch (target.kind) {
-			case "surface":
-				beginFolderDraft(null, 0);
+	const handleContextActionSelect = (action: { id: string; label: string }, target: ProjectMenuTarget): void => {
+		switch (action.id) {
+			case "new-folder":
+				switch (target.kind) {
+					case "surface":
+						beginFolderDraft(null, 0);
+						return;
+					case "folder":
+						beginFolderDraft(target.id, (findTreeNodeDepth(projectTreeNodes(), target.id, projectTreeAdapter) ?? 0) + 1);
+						return;
+					case "project": {
+						const parentId = findTreeNodeLocation(projectTreeNodes(), target.id, projectTreeAdapter)?.parentId ?? null;
+						beginFolderDraft(parentId, parentId ? (findTreeNodeDepth(projectTreeNodes(), parentId, projectTreeAdapter) ?? 0) + 1 : 0);
+						return;
+					}
+				}
 				return;
-			case "folder":
-				beginFolderDraft(target.id, (findProjectNodeDepth(projectTreeNodes(), target.id) ?? 0) + 1);
+			case "delete-folder":
+				if (target.kind === "folder") {
+					void deletePersistedFolder(target.id);
+				}
 				return;
-			case "project": {
-				const parentId = findProjectNodeLocation(projectTreeNodes(), target.id)?.parentId ?? null;
-				beginFolderDraft(parentId, parentId ? (findProjectNodeDepth(projectTreeNodes(), parentId) ?? 0) + 1 : 0);
+			case "rename-folder":
+				if (target.kind === "folder") {
+					beginFolderRename(target.id, target.label, findTreeNodeDepth(projectTreeNodes(), target.id, projectTreeAdapter) ?? 0);
+				}
+				return;
+			default:
 				return;
-			}
 		}
 	};
 
@@ -886,50 +963,20 @@ export const ProjectSelector = (props: ProjectSelectorProps): JSX.Element => {
 			return;
 		}
 
-		const currentTarget = event.currentTarget;
-		if (!(currentTarget instanceof HTMLElement)) {
+		const relativeY = getPointerRelativeY(event);
+		if (relativeY === null) {
 			return;
 		}
 
-		const bounds = currentTarget.getBoundingClientRect();
-		const relativeY = bounds.height <= 0 ? 0.5 : (event.clientY - bounds.top) / bounds.height;
-		let nextTarget: ProjectDragTarget;
-
-		if (node.kind === "folder") {
-			if (relativeY < 0.28) {
-				nextTarget = {
-					parentId,
-					index,
-					intent: "before",
-					targetNodeId: node.id,
-				};
-			} else if (relativeY > 0.72) {
-				nextTarget = {
-					parentId,
-					index: index + 1,
-					intent: "after",
-					targetNodeId: node.id,
-				};
-			} else {
-				nextTarget = {
-					parentId: node.id,
-					index: node.children.length,
-					intent: "inside",
-					targetNodeId: node.id,
-				};
-			}
-		} else {
-			nextTarget = {
-				parentId,
-				index: relativeY < 0.5 ? index : index + 1,
-				intent: relativeY < 0.5 ? "before" : "after",
-				targetNodeId: node.item.id,
-			};
-		}
-
 		setDragState({
 			...nextDragState,
-			dropTarget: nextTarget,
+			dropTarget: resolveTreeDropTarget({
+				parentId,
+				index,
+				node,
+				relativeY,
+				adapter: projectTreeAdapter,
+			}),
 		});
 	};
 
@@ -1047,6 +1094,11 @@ export const ProjectSelector = (props: ProjectSelectorProps): JSX.Element => {
 								onPendingFolderNameChange={setPendingFolderName}
 								onSubmitPendingFolder={submitPendingFolder}
 								onCancelPendingFolder={cancelPendingFolder}
+								pendingFolderRename={pendingFolderRename()}
+								pendingFolderRenameName={pendingFolderRenameName()}
+								onPendingFolderRenameChange={setPendingFolderRenameName}
+								onSubmitPendingFolderRename={submitPendingFolderRename}
+								onCancelPendingFolderRename={cancelPendingFolderRename}
 								dragState={dragState()}
 								isTreeClickSuppressed={suppressNextTreeClick}
 							/>

Frontend/src/components/shell/WorkspaceSidebar/WorkspaceSidebar.module.scss

@@ -1,3 +1,5 @@
+@use "../shared/tree-nav" as treeNav;
+
 .sidebar {
   --sidebar-nav-item-min-height: var(--control-size-lg);
   position: relative;
@@ -117,56 +119,25 @@
 }
 
 .treeSectionLabel {
-  @include text-caption;
+	@include treeNav.section-label;
   margin: var(--space-3) 0 var(--space-2);
   padding: 0 var(--space-3);
-  color: var(--color-text-subtle);
-  text-transform: uppercase;
-  letter-spacing: 0.04em;
 }
 
 .treeList {
-  list-style: none;
-  display: grid;
-  gap: var(--space-1);
-  padding: 0;
+	@include treeNav.tree-list;
 }
 
 .treeEmptySlot {
-	min-height: calc(var(--control-size-lg) - var(--space-2));
-	padding-left: calc(var(--space-3) + (var(--tree-depth, 0) * var(--space-4)));
-	border-radius: var(--radius-lg);
-	border: 1px dashed color-mix(in srgb, var(--color-border) 38%, transparent);
-	opacity: 0.35;
+	@include treeNav.empty-slot;
 }
 
 .treeInputRow {
-	width: 100%;
-	min-width: 0;
-	display: grid;
-	grid-template-columns: auto minmax(0, 1fr);
-	align-items: center;
-	gap: var(--space-2);
-	min-height: calc(var(--control-size-lg) - var(--space-2));
-	padding: var(--space-2) var(--space-3);
-	padding-left: calc(var(--space-3) + (var(--tree-depth, 0) * var(--space-4)));
-	border: 1px solid color-mix(in srgb, var(--color-border) 42%, transparent);
-	border-radius: var(--radius-lg);
-	background: color-mix(in srgb, var(--color-surface) 94%, transparent);
+	@include treeNav.input-row;
 }
 
 .treeInput {
-	width: 100%;
-	min-width: 0;
-	border: 0;
-	background: transparent;
-	color: var(--color-text);
-	font: inherit;
-	outline: none;
-}
-
-.treeInput::placeholder {
-	color: var(--color-text-muted);
+	@include treeNav.input;
 }
 
 .navItem {
@@ -184,74 +155,44 @@
 }
 
 .treeItem {
-  width: 100%;
-  min-width: 0;
-  display: grid;
-  grid-template-columns: auto auto minmax(0, 1fr) auto;
-  align-items: center;
-  gap: var(--space-2);
-  min-height: calc(var(--control-size-lg) - var(--space-2));
-  padding: var(--space-2) var(--space-3);
-  padding-left: calc(var(--space-3) + (var(--tree-depth, 0) * var(--space-4)));
-  border: 1px solid transparent;
-  border-radius: var(--radius-lg);
-  background: transparent;
-  color: var(--color-text-muted);
-  text-align: left;
-  transition:
-    background 160ms var(--easing-standard),
-    color 160ms var(--easing-standard),
-    border-color 160ms var(--easing-standard),
-    box-shadow 160ms var(--easing-standard),
-    transform 180ms var(--easing-standard);
+	@include treeNav.item;
 }
 
 .treeItem:hover,
 .treeItem:focus-visible {
-  background: color-mix(in srgb, var(--color-surface-hover) 80%, var(--color-accent-soft) 20%);
-  color: var(--color-text);
-  box-shadow: inset 0 1px 0 color-mix(in srgb, white 4%, transparent);
+	@include treeNav.item-hover;
 }
 
 .treeItemFolder {
-  color: var(--color-text);
+	@include treeNav.item-folder;
 }
 
 .treeItemDragging {
-	opacity: 0.45;
-	transform: scale(0.985);
-	box-shadow: none;
+	@include treeNav.item-dragging;
 }
 
 .treeItemDropBefore {
-	box-shadow: inset 0 2px 0 color-mix(in srgb, var(--color-accent-strong) 78%, transparent);
+	@include treeNav.item-drop-before;
 }
 
 .treeItemDropAfter {
-	box-shadow: inset 0 -2px 0 color-mix(in srgb, var(--color-accent-strong) 78%, transparent);
+	@include treeNav.item-drop-after;
 }
 
 .treeItemDropInside {
-	border-color: color-mix(in srgb, var(--color-accent-strong) 55%, transparent);
-	background: color-mix(in srgb, var(--color-accent-soft) 36%, var(--color-surface));
-	color: var(--color-text);
-	box-shadow: inset 0 1px 0 color-mix(in srgb, white 4%, transparent);
+	@include treeNav.item-drop-inside;
 }
 
 .folderChevron {
-  color: var(--color-text-muted);
-  transition: transform 160ms var(--easing-standard);
+	@include treeNav.folder-chevron;
 }
 
 .folderChevronOpen {
-  transform: rotate(90deg);
+	@include treeNav.folder-chevron-open;
 }
 
 .treeItemActive {
-  border-color: var(--color-border);
-  background: var(--color-surface);
-  color: var(--color-text);
-  box-shadow: inset 0 1px 0 color-mix(in srgb, white 4%, transparent);
+	@include treeNav.item-active;
 }
 
 .navItemActive {
@@ -262,18 +203,15 @@
 }
 
 .icon {
-  color: inherit;
-  opacity: 0.85;
+	@include treeNav.icon;
 }
 
 .label {
-  @include text-label;
-  min-width: 0;
+	@include treeNav.label;
 }
 
 .itemMeta {
-  @include text-caption;
-  color: var(--color-text-muted);
+	@include treeNav.item-meta;
 }
 
 .sidebarCollapsed {

Frontend/src/components/shell/data/shell.data.ts

@@ -9,6 +9,7 @@ import {
 	Home,
 	Keyboard,
 	LayoutGrid,
+	ListCollapse,
 	LogOut,
 	Repeat,
 	Search,
@@ -128,6 +129,7 @@ export type WorkspaceStaticItem = SidebarItem & {
 
 export type WorkspaceFolderNode = {
 	id: string;
+	path?: string;
 	label: string;
 	kind: "folder";
 	icon: ShellIcon;
@@ -476,6 +478,7 @@ export const workspaceTree: readonly WorkspaceTreeNode[] = [
 
 export const workspaceSidebarHeaderActions: readonly SidebarHeaderAction[] = [
 	{ id: "search-workspace", label: "Search workspace", icon: Search },
+	{ id: "toggle-workspace-folders", label: "Collapse all folders", icon: ListCollapse },
 ] as const;
 
 export const mobileBottomNavItems: readonly MobileBottomNavItem[] = [
@@ -595,6 +598,12 @@ const getProjectCreateActions = (): readonly ProjectContextMenuAction[] =>
 		{ id: "new-folder", label: "New folder" },
 	] as const;
 
+const getProjectFolderDangerActions = (): readonly ProjectContextMenuAction[] =>
+	[
+		{ id: "rename-folder", label: "Rename", shortcut: { modifiers: ["meta"], key: "r" } },
+		{ id: "delete-folder", label: "Delete", shortcut: { modifiers: ["meta"], key: "delete" }, tone: "danger" },
+	] as const;
+
 export const createProjectSurfaceTarget = (label = "Projects"): ProjectMenuTarget => ({
 	id: "project-surface",
 	label,
@@ -641,6 +650,10 @@ export const getProjectContextMenuSections = (target: ProjectMenuTarget): readon
 					id: "create",
 					items: createActions,
 				},
+				{
+					id: "organize",
+					items: getProjectFolderDangerActions(),
+				},
 			] as const;
 		case "project":
 			return [

Frontend/src/components/shell/shared/_tree-nav.scss

@@ -0,0 +1,188 @@
+@use "../../../styles/tools/mixins" as *;
+
+@mixin section-label {
+	@include text-caption;
+	color: var(--color-text-subtle);
+	text-transform: uppercase;
+	letter-spacing: 0.04em;
+}
+
+@mixin tree-list {
+	list-style: none;
+	display: grid;
+	gap: var(--space-1);
+	padding: 0;
+}
+
+@mixin empty-slot {
+	min-height: calc(var(--control-size-lg) - var(--space-2));
+	padding-left: calc(var(--space-3) + (var(--tree-depth, 0) * var(--space-4)));
+	border-radius: var(--radius-lg);
+	border: 1px dashed color-mix(in srgb, var(--color-border) 38%, transparent);
+	opacity: 0.35;
+}
+
+@mixin input-row {
+	width: 100%;
+	min-width: 0;
+	display: grid;
+	grid-template-columns: auto minmax(0, 1fr);
+	align-items: center;
+	gap: var(--space-2);
+	min-height: calc(var(--control-size-lg) - var(--space-2));
+	padding: var(--space-2) var(--space-3);
+	padding-left: calc(var(--space-3) + (var(--tree-depth, 0) * var(--space-4)));
+	border: 1px solid color-mix(in srgb, var(--color-border) 42%, transparent);
+	border-radius: var(--radius-lg);
+	background: color-mix(in srgb, var(--color-surface) 94%, transparent);
+}
+
+@mixin input {
+	width: 100%;
+	min-width: 0;
+	border: 0;
+	background: transparent;
+	color: var(--color-text);
+	font: inherit;
+	outline: none;
+
+	&::placeholder {
+		color: var(--color-text-muted);
+	}
+}
+
+@mixin item {
+	width: 100%;
+	min-width: 0;
+	display: grid;
+	position: relative;
+	isolation: isolate;
+	grid-template-columns: auto auto minmax(0, 1fr) auto;
+	align-items: center;
+	gap: var(--space-2);
+	min-height: calc(var(--control-size-lg) - var(--space-2));
+	padding: var(--space-2) var(--space-3);
+	padding-left: calc(var(--space-3) + (var(--tree-depth, 0) * var(--space-4)));
+	border: 0;
+	border-radius: 0;
+	background: transparent;
+	color: var(--color-text-muted);
+	text-align: left;
+	transition:
+		color 160ms var(--easing-standard),
+		box-shadow 160ms var(--easing-standard),
+		transform 180ms var(--easing-standard);
+
+	&::after {
+		content: "";
+		position: absolute;
+		inset: 0;
+		border: 1px solid transparent;
+		border-radius: var(--radius-lg);
+		background: transparent;
+		transition:
+			background 160ms var(--easing-standard),
+			border-color 160ms var(--easing-standard),
+			box-shadow 160ms var(--easing-standard);
+		pointer-events: none;
+		z-index: 0;
+	}
+
+	> * {
+		position: relative;
+		z-index: 1;
+	}
+}
+
+@mixin item-hover {
+	color: var(--color-text);
+
+	&::after {
+		background: color-mix(in srgb, var(--color-surface-hover) 80%, var(--color-accent-soft) 20%);
+		box-shadow: inset 0 1px 0 color-mix(in srgb, white 4%, transparent);
+	}
+}
+
+@mixin item-folder {
+	color: var(--color-text);
+}
+
+@mixin item-dragging {
+	opacity: 0.45;
+	transform: scale(0.985);
+	box-shadow: none;
+}
+
+@mixin item-drop-before {
+	&::before {
+		content: "";
+		position: absolute;
+		left: calc(var(--space-3) + (var(--tree-depth, 0) * var(--space-4)));
+		right: var(--space-3);
+		top: calc((var(--space-1) * -0.5) - 1px);
+		height: 2px;
+		border-radius: 999px;
+		background: color-mix(in srgb, var(--color-accent-strong) 78%, transparent);
+		pointer-events: none;
+		z-index: 2;
+	}
+}
+
+@mixin item-drop-after {
+	&::before {
+		content: "";
+		position: absolute;
+		left: calc(var(--space-3) + (var(--tree-depth, 0) * var(--space-4)));
+		right: var(--space-3);
+		bottom: calc((var(--space-1) * -0.5) - 1px);
+		height: 2px;
+		border-radius: 999px;
+		background: color-mix(in srgb, var(--color-accent-strong) 78%, transparent);
+		pointer-events: none;
+		z-index: 2;
+	}
+}
+
+@mixin item-drop-inside {
+	color: var(--color-text);
+
+	&::after {
+		border-color: color-mix(in srgb, var(--color-accent-strong) 55%, transparent);
+		background: color-mix(in srgb, var(--color-accent-soft) 36%, var(--color-surface));
+		box-shadow: inset 0 1px 0 color-mix(in srgb, white 4%, transparent);
+	}
+}
+
+@mixin folder-chevron {
+	color: var(--color-text-muted);
+	transition: transform 160ms var(--easing-standard);
+}
+
+@mixin folder-chevron-open {
+	transform: rotate(90deg);
+}
+
+@mixin item-active {
+	color: var(--color-text);
+
+	&::after {
+		border-color: var(--color-border);
+		background: var(--color-surface);
+		box-shadow: inset 0 1px 0 color-mix(in srgb, white 4%, transparent);
+	}
+}
+
+@mixin icon {
+	color: inherit;
+	opacity: 0.85;
+}
+
+@mixin label {
+	@include text-label;
+	min-width: 0;
+}
+
+@mixin item-meta {
+	@include text-caption;
+	color: var(--color-text-muted);
+}

Frontend/src/components/shell/shared/navTreeDnd.ts

@@ -0,0 +1,278 @@
+export type NavTreeDropIntent = "before" | "after" | "inside";
+
+export type NavTreeDropTarget = {
+	parentId: string | null;
+	index: number;
+	intent: NavTreeDropIntent;
+	targetNodeId?: string;
+};
+
+export type NavTreeDragState = {
+	draggedNodeId: string;
+	dropTarget: NavTreeDropTarget | null;
+};
+
+export type NavTreeLocation<TNode> = {
+	parentId: string | null;
+	index: number;
+	node: TNode;
+};
+
+export type NavTreeAdapter<TNode> = {
+	getNodeId: (node: TNode) => string;
+	isBranchNode: (node: TNode) => boolean;
+	getChildren: (node: TNode) => readonly TNode[];
+	withChildren: (node: TNode, children: readonly TNode[]) => TNode;
+};
+
+const UUID_PATTERN = /^[0-9a-f]{8}-[0-9a-f]{4}-[1-5][0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$/i;
+
+export const isUuidString = (value: string | null | undefined): boolean => {
+	if (typeof value !== "string") {
+		return false;
+	}
+
+	return UUID_PATTERN.test(value.trim());
+};
+
+export const collectBranchNodeIds = <TNode>(
+	nodes: readonly TNode[],
+	adapter: NavTreeAdapter<TNode>,
+): string[] => {
+	const ids: string[] = [];
+
+	for (const node of nodes) {
+		if (!adapter.isBranchNode(node)) {
+			continue;
+		}
+
+		ids.push(adapter.getNodeId(node));
+		ids.push(...collectBranchNodeIds(adapter.getChildren(node), adapter));
+	}
+
+	return ids;
+};
+
+export const findTreeNodeLocation = <TNode>(
+	nodes: readonly TNode[],
+	nodeId: string,
+	adapter: NavTreeAdapter<TNode>,
+	parentId: string | null = null,
+): NavTreeLocation<TNode> | null => {
+	for (let index = 0; index < nodes.length; index += 1) {
+		const node = nodes[index];
+
+		if (adapter.getNodeId(node) === nodeId) {
+			return { parentId, index, node };
+		}
+
+		if (!adapter.isBranchNode(node)) {
+			continue;
+		}
+
+		const nestedLocation = findTreeNodeLocation(adapter.getChildren(node), nodeId, adapter, adapter.getNodeId(node));
+		if (nestedLocation) {
+			return nestedLocation;
+		}
+	}
+
+	return null;
+};
+
+export const findTreeNodeDepth = <TNode>(
+	nodes: readonly TNode[],
+	nodeId: string,
+	adapter: NavTreeAdapter<TNode>,
+	depth = 0,
+): number | null => {
+	for (const node of nodes) {
+		if (adapter.getNodeId(node) === nodeId) {
+			return depth;
+		}
+
+		if (!adapter.isBranchNode(node)) {
+			continue;
+		}
+
+		const nestedDepth = findTreeNodeDepth(adapter.getChildren(node), nodeId, adapter, depth + 1);
+		if (nestedDepth !== null) {
+			return nestedDepth;
+		}
+	}
+
+	return null;
+};
+
+export const treeContainsNode = <TNode>(
+	nodes: readonly TNode[],
+	nodeId: string,
+	adapter: NavTreeAdapter<TNode>,
+): boolean => {
+	for (const node of nodes) {
+		if (adapter.getNodeId(node) === nodeId) {
+			return true;
+		}
+
+		if (adapter.isBranchNode(node) && treeContainsNode(adapter.getChildren(node), nodeId, adapter)) {
+			return true;
+		}
+	}
+
+	return false;
+};
+
+export const removeTreeNode = <TNode>(
+	nodes: readonly TNode[],
+	nodeId: string,
+	adapter: NavTreeAdapter<TNode>,
+): { nodes: TNode[]; removed: TNode | null } => {
+	const nextNodes: TNode[] = [];
+	let removed: TNode | null = null;
+
+	for (const node of nodes) {
+		if (adapter.getNodeId(node) === nodeId) {
+			removed = node;
+			continue;
+		}
+
+		if (adapter.isBranchNode(node)) {
+			const result = removeTreeNode(adapter.getChildren(node), nodeId, adapter);
+
+			if (result.removed) {
+				removed = result.removed;
+				nextNodes.push(adapter.withChildren(node, result.nodes));
+				continue;
+			}
+		}
+
+		nextNodes.push(node);
+	}
+
+	return { nodes: nextNodes, removed };
+};
+
+export const insertTreeNode = <TNode>(
+	nodes: readonly TNode[],
+	parentId: string | null,
+	index: number,
+	nodeToInsert: TNode,
+	adapter: NavTreeAdapter<TNode>,
+): TNode[] => {
+	if (parentId === null) {
+		const nextNodes = [...nodes];
+		nextNodes.splice(Math.max(0, Math.min(index, nextNodes.length)), 0, nodeToInsert);
+		return nextNodes;
+	}
+
+	return nodes.map((node) => {
+		if (!adapter.isBranchNode(node)) {
+			return node;
+		}
+
+		if (adapter.getNodeId(node) === parentId) {
+			const nextChildren = [...adapter.getChildren(node)];
+			nextChildren.splice(Math.max(0, Math.min(index, nextChildren.length)), 0, nodeToInsert);
+			return adapter.withChildren(node, nextChildren);
+		}
+
+		return adapter.withChildren(node, insertTreeNode(adapter.getChildren(node), parentId, index, nodeToInsert, adapter));
+	});
+};
+
+export const moveTreeNode = <TNode>(
+	nodes: readonly TNode[],
+	draggedNodeId: string,
+	dropTarget: NavTreeDropTarget,
+	adapter: NavTreeAdapter<TNode>,
+): TNode[] => {
+	const location = findTreeNodeLocation(nodes, draggedNodeId, adapter);
+
+	if (!location) {
+		return [...nodes];
+	}
+
+	if (
+		adapter.isBranchNode(location.node) &&
+		dropTarget.parentId !== null &&
+		(treeContainsNode(adapter.getChildren(location.node), dropTarget.parentId, adapter) ||
+			dropTarget.parentId === adapter.getNodeId(location.node))
+	) {
+		return [...nodes];
+	}
+
+	let normalizedIndex = dropTarget.index;
+	if (dropTarget.parentId === location.parentId && dropTarget.index > location.index) {
+		normalizedIndex -= 1;
+	}
+
+	if (dropTarget.parentId === location.parentId && normalizedIndex === location.index) {
+		return [...nodes];
+	}
+
+	const removalResult = removeTreeNode(nodes, draggedNodeId, adapter);
+	if (!removalResult.removed) {
+		return [...nodes];
+	}
+
+	return insertTreeNode(removalResult.nodes, dropTarget.parentId, normalizedIndex, removalResult.removed, adapter);
+};
+
+export const getPointerRelativeY = (event: PointerEvent): number | null => {
+	const currentTarget = event.currentTarget;
+	if (!(currentTarget instanceof HTMLElement)) {
+		return null;
+	}
+
+	const bounds = currentTarget.getBoundingClientRect();
+	return bounds.height <= 0 ? 0.5 : (event.clientY - bounds.top) / bounds.height;
+};
+
+export const resolveTreeDropTarget = <TNode>(params: {
+	parentId: string | null;
+	index: number;
+	node: TNode;
+	relativeY: number;
+	adapter: NavTreeAdapter<TNode>;
+	beforeThreshold?: number;
+	beforeThresholdFirstSibling?: number;
+	afterThreshold?: number;
+}): NavTreeDropTarget => {
+	const {
+		parentId,
+		index,
+		node,
+		relativeY,
+		adapter,
+		beforeThreshold = 0.28,
+		beforeThresholdFirstSibling = 0.42,
+		afterThreshold = 0.72,
+	} = params;
+
+	const targetNodeId = adapter.getNodeId(node);
+
+	if (adapter.isBranchNode(node)) {
+		const nextBeforeThreshold = index === 0 ? beforeThresholdFirstSibling : beforeThreshold;
+
+		if (relativeY < nextBeforeThreshold) {
+			return { parentId, index, intent: "before", targetNodeId };
+		}
+
+		if (relativeY > afterThreshold) {
+			return { parentId, index: index + 1, intent: "after", targetNodeId };
+		}
+
+		return {
+			parentId: targetNodeId,
+			index: adapter.getChildren(node).length,
+			intent: "inside",
+			targetNodeId,
+		};
+	}
+
+	return {
+		parentId,
+		index: relativeY < 0.5 ? index : index + 1,
+		intent: relativeY < 0.5 ? "before" : "after",
+		targetNodeId,
+	};
+};

Frontend/src/components/workspace-home/WorkspaceHome/WorkspaceHome.tsx

@@ -21,6 +21,29 @@ type BootstrapSubmissionState = {
 	error: string;
 };
 
+type InstanceForm = {
+	protocol: "http" | "https";
+	access: "local" | "remote";
+	host: string;
+};
+
+type ModeForm = {
+	mode: "personal" | "organizational";
+	name: string;
+};
+
+type AdminForm = {
+	displayName: string;
+	email: string;
+	password: string;
+};
+
+type StructureForm = {
+	departmentName: string;
+	teamName: string;
+	projectName: string;
+};
+
 const bootstrapStepDefinitions: readonly BootstrapStepDefinition[] = [
 	{
 		id: "instance",
@@ -44,37 +67,37 @@ const bootstrapStepDefinitions: readonly BootstrapStepDefinition[] = [
 	},
 ];
 
-const defaultInstanceForm = {
+const defaultInstanceForm: InstanceForm = {
 	protocol: "http",
 	access: "local",
 	host: "localhost",
-} as const;
+};
 
-const defaultModeForm = {
+const defaultModeForm: ModeForm = {
 	mode: "personal",
 	name: "",
-} as const;
+};
 
-const defaultAdminForm = {
+const defaultAdminForm: AdminForm = {
 	displayName: "Admin",
 	email: "admin@example.com",
 	password: "",
-} as const;
+};
 
 const personalStructureDefaults = {
 	departmentName: "Default",
 	teamName: "Personal",
-} as const;
+};
 
 const organizationalStructureDefaults = {
 	departmentName: "Department",
 	teamName: "Team",
-} as const;
+};
 
-const defaultStructureForm = {
+const defaultStructureForm: StructureForm = {
 	...personalStructureDefaults,
 	projectName: "Project",
-} as const;
+};
 
 const initialSubmissionState = (): BootstrapSubmissionState => ({
 	status: "idle",
@@ -148,10 +171,10 @@ type WorkspaceHomeProps = {
 
 export const WorkspaceHome = (props: WorkspaceHomeProps): JSX.Element => {
 	const appShellData = useAppShellData();
-	const [instanceForm, setInstanceForm] = createStore({ ...defaultInstanceForm });
-	const [modeForm, setModeForm] = createStore({ ...defaultModeForm });
-	const [adminForm, setAdminForm] = createStore({ ...defaultAdminForm });
-	const [structureForm, setStructureForm] = createStore({ ...defaultStructureForm });
+	const [instanceForm, setInstanceForm] = createStore<InstanceForm>({ ...defaultInstanceForm });
+	const [modeForm, setModeForm] = createStore<ModeForm>({ ...defaultModeForm });
+	const [adminForm, setAdminForm] = createStore<AdminForm>({ ...defaultAdminForm });
+	const [structureForm, setStructureForm] = createStore<StructureForm>({ ...defaultStructureForm });
 	const [stepState, setStepState] = createStore<Record<BootstrapStepKey, BootstrapSubmissionState>>({
 		instance: initialSubmissionState(),
 		mode: initialSubmissionState(),
@@ -363,7 +386,13 @@ export const WorkspaceHome = (props: WorkspaceHomeProps): JSX.Element => {
 					<h1 class={styles.title}>{isBootstrapComplete() ? appShellData.activeServer().name : bootstrapTargetLabel()}</h1>
 					<Show when={isBootstrapStateResolved() && !isBootstrapComplete()}>
 						<div class={styles.heroActions}>
-							<button type="button" class={styles.primaryButton} onClick={(): void => setIsWizardOpen(true)}>
+						<button
+							type="button"
+							class={styles.primaryButton}
+							onClick={(): void => {
+								setIsWizardOpen(true);
+							}}
+						>
 								Open bootstrap wizard
 							</button>
 						</div>
@@ -384,7 +413,13 @@ export const WorkspaceHome = (props: WorkspaceHomeProps): JSX.Element => {
 									</h2>
 								</div>
 								<Show when={canDismissWizard()}>
-									<button type="button" class={styles.wizardCloseButton} onClick={(): void => setIsWizardOpen(false)}>
+									<button
+										type="button"
+										class={styles.wizardCloseButton}
+										onClick={(): void => {
+											setIsWizardOpen(false);
+										}}
+									>
 										Close
 									</button>
 								</Show>
@@ -433,14 +468,24 @@ export const WorkspaceHome = (props: WorkspaceHomeProps): JSX.Element => {
 											<>
 												<label class={styles.field}>
 													<span class={styles.fieldLabel}>Protocol</span>
-													<select value={instanceForm.protocol} onInput={(event): void => setInstanceForm("protocol", event.currentTarget.value)}>
+												<select
+													value={instanceForm.protocol}
+													onInput={(event): void =>
+														setInstanceForm("protocol", event.currentTarget.value as InstanceForm["protocol"])
+													}
+												>
 														<option value="http">http</option>
 														<option value="https">https</option>
 													</select>
 												</label>
 												<label class={styles.field}>
 													<span class={styles.fieldLabel}>Access</span>
-													<select value={instanceForm.access} onInput={(event): void => setInstanceForm("access", event.currentTarget.value)}>
+												<select
+													value={instanceForm.access}
+													onInput={(event): void =>
+														setInstanceForm("access", event.currentTarget.value as InstanceForm["access"])
+													}
+												>
 														<option value="local">local</option>
 														<option value="remote">remote</option>
 													</select>
@@ -461,7 +506,10 @@ export const WorkspaceHome = (props: WorkspaceHomeProps): JSX.Element => {
 							<>
 								<label class={styles.field}>
 									<span class={styles.fieldLabel}>Mode</span>
-									<select value={modeForm.mode} onInput={(event): void => setModeForm("mode", event.currentTarget.value)}>
+								<select
+									value={modeForm.mode}
+									onInput={(event): void => setModeForm("mode", event.currentTarget.value as ModeForm["mode"])}
+								>
 										<option value="personal">personal</option>
 										<option value="organizational">organizational</option>
 									</select>
@@ -553,7 +601,9 @@ export const WorkspaceHome = (props: WorkspaceHomeProps): JSX.Element => {
 												type="button"
 												class={styles.secondaryButton}
 												disabled={isFirstStep()}
-												onClick={(): void => setCurrentStepIndex((index) => Math.max(index - 1, 0))}
+												onClick={(): void => {
+													setCurrentStepIndex((index) => Math.max(index - 1, 0));
+												}}
 											>
 												Back
 											</button>