Merge branch 'Features/Backend/Posix-DB-Projection'

.gitignore

@@ -27,3 +27,5 @@ tmp/
 bin/
 
 .cgcignore
+
+POSIX/

Backend/cmd/posix/main.go

@@ -0,0 +1,52 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"log"
+	"os"
+
+	"moku-backend/internal/config"
+	"moku-backend/internal/database"
+	"moku-backend/internal/posixproj"
+)
+
+func main() {
+	command := "rebuild"
+	if len(os.Args) > 1 {
+		command = os.Args[1]
+	}
+
+	switch command {
+	case "rebuild":
+		if err := rebuildProjection(context.Background()); err != nil {
+			log.Fatalf("rebuild POSIX projection: %v", err)
+		}
+	default:
+		log.Fatalf("unsupported posix command %q (supported: rebuild)", command)
+	}
+}
+
+func rebuildProjection(ctx context.Context) error {
+	cfg := config.Load()
+
+	db, err := database.NewPostgres(cfg.PostgresURL)
+	if err != nil {
+		return fmt.Errorf("connect database: %w", err)
+	}
+	defer db.Close()
+
+	summary, err := posixproj.NewProjector(db, cfg.POSIXRoot).RebuildWithSummary(ctx)
+	if err != nil {
+		return err
+	}
+
+	fmt.Printf(
+		"POSIX projection rebuilt from %s\n  total nodes: %d\n  directories: %d\n  files: %d\n",
+		cfg.POSIXRoot,
+		summary.TotalNodes,
+		summary.DirectoryCount,
+		summary.FileCount,
+	)
+	return nil
+}

Backend/db/migrations/000004_posix_nodes.sql

@@ -0,0 +1,45 @@
+-- +goose Up
+
+CREATE TYPE posix_node_kind AS ENUM ('directory', 'file');
+
+CREATE TABLE IF NOT EXISTS posix_nodes (
+  id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+  path TEXT NOT NULL UNIQUE,
+  parent_path TEXT,
+  name TEXT NOT NULL,
+  depth INTEGER NOT NULL,
+  node_kind posix_node_kind NOT NULL,
+  logical_type TEXT NOT NULL DEFAULT 'generic',
+  file_role TEXT,
+  resource_id TEXT,
+  resource_name TEXT,
+  resource_slug TEXT,
+  installation_id TEXT,
+  organization_id TEXT,
+  organization_slug TEXT,
+  department_slug TEXT,
+  team_slug TEXT,
+  project_slug TEXT,
+  personal_slug TEXT,
+  content_json JSONB,
+  size_bytes BIGINT NOT NULL DEFAULT 0,
+  checksum TEXT,
+  created_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+  updated_at TIMESTAMPTZ NOT NULL DEFAULT NOW()
+);
+
+CREATE INDEX IF NOT EXISTS idx_posix_nodes_parent_path ON posix_nodes (parent_path);
+CREATE INDEX IF NOT EXISTS idx_posix_nodes_logical_type ON posix_nodes (logical_type);
+CREATE INDEX IF NOT EXISTS idx_posix_nodes_project_slug ON posix_nodes (project_slug);
+CREATE INDEX IF NOT EXISTS idx_posix_nodes_department_slug ON posix_nodes (department_slug);
+CREATE INDEX IF NOT EXISTS idx_posix_nodes_team_slug ON posix_nodes (team_slug);
+
+-- +goose Down
+
+DROP INDEX IF EXISTS idx_posix_nodes_team_slug;
+DROP INDEX IF EXISTS idx_posix_nodes_department_slug;
+DROP INDEX IF EXISTS idx_posix_nodes_project_slug;
+DROP INDEX IF EXISTS idx_posix_nodes_logical_type;
+DROP INDEX IF EXISTS idx_posix_nodes_parent_path;
+DROP TABLE IF EXISTS posix_nodes;
+DROP TYPE IF EXISTS posix_node_kind;

Backend/internal/bootstrap/service.go

@@ -4,13 +4,17 @@ package bootstrap
 
 import (
 	"context"
+	"encoding/json"
 	"errors"
 	"fmt"
+	"os"
+	"path/filepath"
 	"strings"
 
 	"github.com/jackc/pgx/v5"
 
 	"moku-backend/internal/database"
+	"moku-backend/internal/posixproj"
 )
 
 const (
@@ -42,6 +46,7 @@ var (
 
 type Service struct {
 	db        *database.DB
+	posixRoot string
 }
 
 type SaveInstanceInput struct {
@@ -172,8 +177,8 @@ type namedRecord struct {
 	Slug string `json:"slug"`
 }
 
-func NewService(db *database.DB) *Service {
+func NewService(db *database.DB, posixRoot string) *Service {
-	return &Service{db: db}
+	return &Service{db: db, posixRoot: strings.TrimSpace(posixRoot)}
 }
 
 func (service *Service) SaveInstance(ctx context.Context, input SaveInstanceInput) (InstallationRecord, error) {
@@ -405,6 +410,14 @@ func (service *Service) SaveStructure(ctx context.Context, input SaveStructureIn
 		return StructureRecord{}, err
 	}
 
+	if err := service.ensureBootstrapPOSIXSkeleton(installation, admin, organization, department, team, project); err != nil {
+		return StructureRecord{}, err
+	}
+
+	if err := posixproj.NewProjector(service.db, service.posixRoot).Rebuild(ctx); err != nil {
+		return StructureRecord{}, fmt.Errorf("rebuild POSIX projection: %w", err)
+	}
+
 	return StructureRecord{
 		Installation: installation,
 		Organization: organization,
@@ -901,3 +914,173 @@ func personalHomeTitle(displayName string) string {
 
 	return fmt.Sprintf("%s's Home", trimmedDisplayName)
 }
+
+func (service *Service) ensureBootstrapPOSIXSkeleton(
+	installation InstallationRecord,
+	admin AdminSummary,
+	organization namedRecord,
+	department namedRecord,
+	team namedRecord,
+	project namedRecord,
+) error {
+	rootPath := strings.TrimSpace(service.posixRoot)
+	if rootPath == "" {
+		return nil
+	}
+
+	if err := os.MkdirAll(rootPath, 0o755); err != nil {
+		return fmt.Errorf("create POSIX root: %w", err)
+	}
+
+	if err := writeJSONFile(filepath.Join(rootPath, "settings.json"), map[string]any{
+		"installation": map[string]any{
+			"id":             installation.ID,
+			"name":           installation.Name,
+			"mode":           installation.Mode,
+			"access":         installation.Access,
+			"protocol":       installation.Protocol,
+			"host":           installation.Host,
+			"isBootstrapped": installation.IsBootstrapped,
+		},
+		"organization": map[string]any{
+			"id":   organization.ID,
+			"name": organization.Name,
+			"slug": organization.Slug,
+		},
+	}); err != nil {
+		return fmt.Errorf("write tenant settings.json: %w", err)
+	}
+
+	if err := writeJSONFile(filepath.Join(rootPath, "layout.json"), map[string]any{
+		"version": 1,
+		"type":    "tenant-layout",
+		"home": map[string]any{
+			"defaultProjectSlug": project.Slug,
+		},
+	}); err != nil {
+		return fmt.Errorf("write tenant layout.json: %w", err)
+	}
+
+	if err := os.MkdirAll(filepath.Join(rootPath, "catalog", "packs"), 0o755); err != nil {
+		return fmt.Errorf("create catalog packs root: %w", err)
+	}
+
+	if err := os.MkdirAll(filepath.Join(rootPath, "catalog", "standalone"), 0o755); err != nil {
+		return fmt.Errorf("create catalog standalone root: %w", err)
+	}
+
+	departmentPath := filepath.Join(rootPath, "departments", slugDir("department", department.Slug))
+	teamPath := filepath.Join(departmentPath, "teams", slugDir("team", team.Slug))
+	projectPath := filepath.Join(rootPath, "projects", slugDir("project", project.Slug))
+	usersPath := filepath.Join(rootPath, "users")
+
+	for _, dirPath := range []string{
+		departmentPath,
+		teamPath,
+		projectPath,
+		filepath.Join(projectPath, "tree"),
+		filepath.Join(usersPath, "personals"),
+	} {
+		if err := os.MkdirAll(dirPath, 0o755); err != nil {
+			return fmt.Errorf("create POSIX directory %s: %w", dirPath, err)
+		}
+	}
+
+	if err := writeJSONFile(filepath.Join(departmentPath, "settings.json"), map[string]any{
+		"id":   department.ID,
+		"name": department.Name,
+		"slug": department.Slug,
+		"type": "department",
+	}); err != nil {
+		return fmt.Errorf("write department settings.json: %w", err)
+	}
+
+	if err := writeJSONFile(filepath.Join(departmentPath, "users.json"), map[string]any{
+		"owners": []map[string]string{{
+			"id":          admin.ID,
+			"email":       admin.Email,
+			"displayName": admin.DisplayName,
+		}},
+	}); err != nil {
+		return fmt.Errorf("write department users.json: %w", err)
+	}
+
+	if err := writeJSONFile(filepath.Join(teamPath, "settings.json"), map[string]any{
+		"id":   team.ID,
+		"name": team.Name,
+		"slug": team.Slug,
+		"type": "team",
+	}); err != nil {
+		return fmt.Errorf("write team settings.json: %w", err)
+	}
+
+	if err := writeJSONFile(filepath.Join(teamPath, "users.json"), map[string]any{
+		"owners": []map[string]string{{
+			"id":          admin.ID,
+			"email":       admin.Email,
+			"displayName": admin.DisplayName,
+		}},
+	}); err != nil {
+		return fmt.Errorf("write team users.json: %w", err)
+	}
+
+	if err := writeJSONFile(filepath.Join(projectPath, "settings.json"), map[string]any{
+		"id":   project.ID,
+		"name": project.Name,
+		"slug": project.Slug,
+		"type": "project",
+	}); err != nil {
+		return fmt.Errorf("write project settings.json: %w", err)
+	}
+
+	if err := writeJSONFile(filepath.Join(projectPath, "home.json"), map[string]any{
+		"type":    "project-home",
+		"project": project.Slug,
+		"widgets": []any{},
+	}); err != nil {
+		return fmt.Errorf("write project home.json: %w", err)
+	}
+
+	if err := writeJSONFile(filepath.Join(usersPath, "settings.json"), map[string]any{
+		"primaryAdminId": admin.ID,
+	}); err != nil {
+		return fmt.Errorf("write users settings.json: %w", err)
+	}
+
+	if err := writeJSONFile(filepath.Join(usersPath, "data.json"), map[string]any{
+		"users": []map[string]string{{
+			"id":          admin.ID,
+			"email":       admin.Email,
+			"displayName": admin.DisplayName,
+		}},
+	}); err != nil {
+		return fmt.Errorf("write users data.json: %w", err)
+	}
+
+	return nil
+}
+
+func slugDir(prefix, slug string) string {
+	trimmedSlug := strings.TrimSpace(slug)
+	if trimmedSlug == "" {
+		return prefix
+	}
+
+	return fmt.Sprintf("%s-%s", prefix, trimmedSlug)
+}
+
+func writeJSONFile(path string, payload any) error {
+	parentDir := filepath.Dir(path)
+	if err := os.MkdirAll(parentDir, 0o755); err != nil {
+		return err
+	}
+
+	data, err := json.MarshalIndent(payload, "", "  ")
+	if err != nil {
+		return err
+	}
+
+	data = append(data, '\n')
+
+	return os.WriteFile(path, data, 0o644)
+}

Backend/internal/bootstrap/service_test.go

@@ -0,0 +1,113 @@
+package bootstrap
+
+import (
+	"encoding/json"
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+func TestEnsureBootstrapPOSIXSkeletonInitializesEmptyRoot(t *testing.T) {
+	rootPath := filepath.Join(t.TempDir(), "POSIX")
+	t.Setenv("POSIX_ROOT", rootPath)
+
+	if _, err := os.Stat(rootPath); !os.IsNotExist(err) {
+		t.Fatalf("expected isolated POSIX root to start absent, got err=%v", err)
+	}
+
+	service := NewService(nil, os.Getenv("POSIX_ROOT"))
+
+	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)
+	}
+
+	requiredPaths := []string{
+		filepath.Join(rootPath, "settings.json"),
+		filepath.Join(rootPath, "layout.json"),
+		filepath.Join(rootPath, "catalog", "packs"),
+		filepath.Join(rootPath, "catalog", "standalone"),
+		filepath.Join(rootPath, "departments", "department-primary-department", "settings.json"),
+		filepath.Join(rootPath, "departments", "department-primary-department", "users.json"),
+		filepath.Join(rootPath, "departments", "department-primary-department", "teams", "team-primary-team", "settings.json"),
+		filepath.Join(rootPath, "departments", "department-primary-department", "teams", "team-primary-team", "users.json"),
+		filepath.Join(rootPath, "projects", "project-primary-project", "settings.json"),
+		filepath.Join(rootPath, "projects", "project-primary-project", "home.json"),
+		filepath.Join(rootPath, "projects", "project-primary-project", "tree"),
+		filepath.Join(rootPath, "users", "settings.json"),
+		filepath.Join(rootPath, "users", "data.json"),
+		filepath.Join(rootPath, "users", "personals"),
+	}
+
+	for _, path := range requiredPaths {
+		if _, err := os.Stat(path); err != nil {
+			t.Fatalf("expected path to exist %s: %v", path, err)
+		}
+	}
+
+	settingsPayload := readJSONFileForTest[map[string]any](t, filepath.Join(rootPath, "settings.json"))
+	installationPayload, ok := settingsPayload["installation"].(map[string]any)
+	if !ok {
+		t.Fatalf("settings.json missing installation object: %#v", settingsPayload)
+	}
+	if installationPayload["name"] != "MangoPig" {
+		t.Fatalf("expected installation name MangoPig, got %#v", installationPayload["name"])
+	}
+	if installationPayload["isBootstrapped"] != true {
+		t.Fatalf("expected installation to be bootstrapped, got %#v", installationPayload["isBootstrapped"])
+	}
+
+	layoutPayload := readJSONFileForTest[map[string]any](t, filepath.Join(rootPath, "layout.json"))
+	homePayload, ok := layoutPayload["home"].(map[string]any)
+	if !ok {
+		t.Fatalf("layout.json missing home object: %#v", layoutPayload)
+	}
+	if homePayload["defaultProjectSlug"] != "primary-project" {
+		t.Fatalf("expected default project slug primary-project, got %#v", homePayload["defaultProjectSlug"])
+	}
+
+	projectSettings := readJSONFileForTest[map[string]any](t, filepath.Join(rootPath, "projects", "project-primary-project", "settings.json"))
+	if projectSettings["type"] != "project" {
+		t.Fatalf("expected project settings type project, got %#v", projectSettings["type"])
+	}
+
+	usersSettings := readJSONFileForTest[map[string]any](t, filepath.Join(rootPath, "users", "settings.json"))
+	if usersSettings["primaryAdminId"] != "admin-1" {
+		t.Fatalf("expected primary admin id admin-1, got %#v", usersSettings["primaryAdminId"])
+	}
+}
+
+func readJSONFileForTest[T any](t *testing.T, path string) T {
+	t.Helper()
+
+	data, err := os.ReadFile(path)
+	if err != nil {
+		t.Fatalf("read %s: %v", path, err)
+	}
+
+	var payload T
+	if err := json.Unmarshal(data, &payload); err != nil {
+		t.Fatalf("unmarshal %s: %v", path, err)
+	}
+
+	return payload
+}

Backend/internal/config/config.go

@@ -17,6 +17,7 @@ type Config struct {
 	APIPort         string
 	PostgresURL     string
 	ValkeyURL       string
+	POSIXRoot       string
 	ShutdownTimeout time.Duration
 }
 
@@ -29,6 +30,7 @@ func Load() *Config {
 		APIPort:         getEnv("BACKEND_API_PORT", "8081"),
 		PostgresURL:     getEnv("DATABASE_URL", "postgres://moku:moku_dev_password@localhost:5432/moku?sslmode=disable"),
 		ValkeyURL:       getEnv("VALKEY_URL", "redis://localhost:6379/0"),
+		POSIXRoot:       getEnv("POSIX_ROOT", "../POSIX"),
 		ShutdownTimeout: getDurationEnv("BACKEND_SHUTDOWN_TIMEOUT", 10*time.Second),
 	}
 }

Backend/internal/httpx/api_bootstrap_routes.go

@@ -341,7 +341,7 @@ func (routes apiRoutes) handleBootstrapStructureStep(w http.ResponseWriter, r *h
 }
 
 func (routes apiRoutes) bootstrapService() *bootstrapservice.Service {
-	return bootstrapservice.NewService(routes.cfg.Database)
+	return bootstrapservice.NewService(routes.cfg.Database, routes.cfg.Config.POSIXRoot)
 }
 
 func (routes apiRoutes) writeBootstrapStepResponse(w http.ResponseWriter, status int, step string, payload any) {

Backend/internal/posixproj/projector.go

@@ -0,0 +1,531 @@
+package posixproj
+
+import (
+	"context"
+	"crypto/sha256"
+	"encoding/hex"
+	"encoding/json"
+	"fmt"
+	"io/fs"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"moku-backend/internal/database"
+)
+
+const rootProjectionPath = "/"
+
+type Projector struct {
+	db   *database.DB
+	root string
+}
+
+type RebuildSummary struct {
+	TotalNodes      int
+	DirectoryCount  int
+	FileCount       int
+}
+
+type NodeKind string
+
+const (
+	NodeKindDirectory NodeKind = "directory"
+	NodeKindFile      NodeKind = "file"
+)
+
+type Scope struct {
+	InstallationID  string
+	OrganizationID  string
+	OrganizationSlug string
+	DepartmentSlug  string
+	TeamSlug        string
+	ProjectSlug     string
+	PersonalSlug    string
+}
+
+type Node struct {
+	Path            string
+	ParentPath      *string
+	Name            string
+	Depth           int
+	NodeKind        NodeKind
+	LogicalType     string
+	FileRole        string
+	ResourceID      string
+	ResourceName    string
+	ResourceSlug    string
+	InstallationID  string
+	OrganizationID  string
+	OrganizationSlug string
+	DepartmentSlug  string
+	TeamSlug        string
+	ProjectSlug     string
+	PersonalSlug    string
+	ContentJSON     []byte
+	SizeBytes       int64
+	Checksum        string
+}
+
+func NewProjector(db *database.DB, root string) *Projector {
+	return &Projector{db: db, root: strings.TrimSpace(root)}
+}
+
+func (projector *Projector) Rebuild(ctx context.Context) error {
+	_, err := projector.RebuildWithSummary(ctx)
+	return err
+}
+
+func (projector *Projector) RebuildWithSummary(ctx context.Context) (RebuildSummary, error) {
+	if projector == nil || projector.db == nil || projector.db.Pool == nil {
+		return RebuildSummary{}, nil
+	}
+
+	nodes, err := ScanRoot(projector.root)
+	if err != nil {
+		return RebuildSummary{}, err
+	}
+
+	summary := summarizeNodes(nodes)
+
+	tx, err := projector.db.Pool.Begin(ctx)
+	if err != nil {
+		return RebuildSummary{}, err
+	}
+	defer func() {
+		_ = tx.Rollback(ctx)
+	}()
+
+	if _, err := tx.Exec(ctx, `DELETE FROM posix_nodes;`); err != nil {
+		return RebuildSummary{}, fmt.Errorf("clear posix_nodes: %w", err)
+	}
+
+	for _, node := range nodes {
+		if _, err := tx.Exec(ctx, `
+			INSERT INTO posix_nodes (
+				path,
+				parent_path,
+				name,
+				depth,
+				node_kind,
+				logical_type,
+				file_role,
+				resource_id,
+				resource_name,
+				resource_slug,
+				installation_id,
+				organization_id,
+				organization_slug,
+				department_slug,
+				team_slug,
+				project_slug,
+				personal_slug,
+				content_json,
+				size_bytes,
+				checksum
+			) VALUES (
+				$1, $2, $3, $4, $5::posix_node_kind, $6, $7, $8, $9, $10,
+				$11, $12, $13, $14, $15, $16, $17, $18::jsonb, $19, $20
+			);
+		`,
+			node.Path,
+			node.ParentPath,
+			node.Name,
+			node.Depth,
+			string(node.NodeKind),
+			node.LogicalType,
+			node.FileRole,
+			node.ResourceID,
+			node.ResourceName,
+			node.ResourceSlug,
+			node.InstallationID,
+			node.OrganizationID,
+			node.OrganizationSlug,
+			node.DepartmentSlug,
+			node.TeamSlug,
+			node.ProjectSlug,
+			node.PersonalSlug,
+				node.ContentJSON,
+				node.SizeBytes,
+				node.Checksum,
+		); err != nil {
+			return RebuildSummary{}, fmt.Errorf("insert posix node %s: %w", node.Path, err)
+		}
+	}
+
+	if err := tx.Commit(ctx); err != nil {
+		return RebuildSummary{}, err
+	}
+
+	return summary, nil
+}
+
+func ScanRoot(root string) ([]Node, error) {
+	rootPath := strings.TrimSpace(root)
+	if rootPath == "" {
+		return nil, nil
+	}
+
+	info, err := os.Stat(rootPath)
+	if err != nil {
+		return nil, fmt.Errorf("stat POSIX root: %w", err)
+	}
+	if !info.IsDir() {
+		return nil, fmt.Errorf("POSIX root is not a directory: %s", rootPath)
+	}
+
+	rootScope, err := loadRootScope(rootPath)
+	if err != nil {
+		return nil, err
+	}
+
+	nodes := []Node{{
+		Path:             rootProjectionPath,
+		ParentPath:       nil,
+		Name:             filepath.Base(rootPath),
+		Depth:            0,
+		NodeKind:         NodeKindDirectory,
+		LogicalType:      "tenant_root",
+		InstallationID:   rootScope.InstallationID,
+		OrganizationID:   rootScope.OrganizationID,
+		OrganizationSlug: rootScope.OrganizationSlug,
+	}}
+
+	err = filepath.WalkDir(rootPath, func(path string, entry fs.DirEntry, walkErr error) error {
+		if walkErr != nil {
+			return walkErr
+		}
+		if path == rootPath {
+			return nil
+		}
+
+		relPath, err := filepath.Rel(rootPath, path)
+		if err != nil {
+			return err
+		}
+		relPath = filepath.ToSlash(relPath)
+		if relPath == "." {
+			return nil
+		}
+
+		node, err := buildNode(rootPath, relPath, entry, rootScope)
+		if err != nil {
+			return err
+		}
+
+		nodes = append(nodes, node)
+		return nil
+	})
+	if err != nil {
+		return nil, fmt.Errorf("scan POSIX root: %w", err)
+	}
+
+	return nodes, nil
+}
+
+func loadRootScope(rootPath string) (Scope, error) {
+	settingsPath := filepath.Join(rootPath, "settings.json")
+	content, err := os.ReadFile(settingsPath)
+	if err != nil {
+		if errorsIsNotExist(err) {
+			return Scope{}, nil
+		}
+		return Scope{}, fmt.Errorf("read root settings.json: %w", err)
+	}
+
+	var payload map[string]any
+	if err := json.Unmarshal(content, &payload); err != nil {
+		return Scope{}, fmt.Errorf("decode root settings.json: %w", err)
+	}
+
+	installation, _ := payload["installation"].(map[string]any)
+	organization, _ := payload["organization"].(map[string]any)
+
+	return Scope{
+		InstallationID:  stringValue(installation["id"]),
+		OrganizationID:  stringValue(organization["id"]),
+		OrganizationSlug: stringValue(organization["slug"]),
+	}, nil
+}
+
+func buildNode(rootPath, relPath string, entry fs.DirEntry, rootScope Scope) (Node, error) {
+	scope := deriveScope(relPath, rootScope)
+	parentPath := projectionParentPath(relPath)
+	logicalType, fileRole := classifyPath(relPath, entry.IsDir())
+
+	node := Node{
+		Path:             relPath,
+		ParentPath:       parentPath,
+		Name:             entry.Name(),
+		Depth:            strings.Count(relPath, "/") + 1,
+		NodeKind:         NodeKindDirectory,
+		LogicalType:      logicalType,
+		FileRole:         fileRole,
+		InstallationID:   scope.InstallationID,
+		OrganizationID:   scope.OrganizationID,
+		OrganizationSlug: scope.OrganizationSlug,
+		DepartmentSlug:   scope.DepartmentSlug,
+		TeamSlug:         scope.TeamSlug,
+		ProjectSlug:      scope.ProjectSlug,
+		PersonalSlug:     scope.PersonalSlug,
+	}
+
+	if entry.IsDir() {
+		return node, nil
+	}
+
+	absPath := filepath.Join(rootPath, filepath.FromSlash(relPath))
+	content, err := os.ReadFile(absPath)
+	if err != nil {
+		return Node{}, fmt.Errorf("read POSIX file %s: %w", relPath, err)
+	}
+
+	hash := sha256.Sum256(content)
+	node.NodeKind = NodeKindFile
+	node.SizeBytes = int64(len(content))
+	node.Checksum = hex.EncodeToString(hash[:])
+
+	if strings.EqualFold(filepath.Ext(entry.Name()), ".json") {
+		var payload map[string]any
+		if err := json.Unmarshal(content, &payload); err == nil {
+			jsonContent, err := json.Marshal(payload)
+			if err != nil {
+				return Node{}, fmt.Errorf("remarshal POSIX file %s: %w", relPath, err)
+			}
+			node.ContentJSON = jsonContent
+			node.ResourceID = stringValue(payload["id"])
+			node.ResourceName = stringValue(payload["name"])
+			node.ResourceSlug = stringValue(payload["slug"])
+			if node.ResourceID == "" && fileRole == "settings" && logicalType == "tenant" {
+				installation, _ := payload["installation"].(map[string]any)
+				organization, _ := payload["organization"].(map[string]any)
+				node.ResourceID = stringValue(installation["id"])
+				node.ResourceName = stringValue(installation["name"])
+				node.InstallationID = stringValue(installation["id"])
+				node.OrganizationID = stringValue(organization["id"])
+				node.OrganizationSlug = firstNonEmpty(node.OrganizationSlug, stringValue(organization["slug"]))
+			}
+			if node.ResourceID == "" && fileRole == "users" {
+				node.ResourceName = firstNonEmpty(node.ResourceName, parentEntityName(logicalType, scope))
+			}
+		}
+	}
+
+	if node.ResourceSlug == "" {
+		node.ResourceSlug = inferredResourceSlug(logicalType, scope)
+	}
+
+	return node, nil
+}
+
+func deriveScope(relPath string, rootScope Scope) Scope {
+	scope := rootScope
+	parts := strings.Split(relPath, "/")
+	if len(parts) >= 2 && parts[0] == "departments" && strings.HasPrefix(parts[1], "department-") {
+		scope.DepartmentSlug = strings.TrimPrefix(parts[1], "department-")
+	}
+	if len(parts) >= 4 && parts[0] == "departments" && parts[2] == "teams" && strings.HasPrefix(parts[3], "team-") {
+		scope.DepartmentSlug = strings.TrimPrefix(parts[1], "department-")
+		scope.TeamSlug = strings.TrimPrefix(parts[3], "team-")
+	}
+	if len(parts) >= 2 && parts[0] == "projects" && strings.HasPrefix(parts[1], "project-") {
+		scope.ProjectSlug = strings.TrimPrefix(parts[1], "project-")
+	}
+	if len(parts) >= 3 && parts[0] == "users" && parts[1] == "personals" && strings.HasPrefix(parts[2], "personal-") {
+		scope.PersonalSlug = strings.TrimPrefix(parts[2], "personal-")
+	}
+	return scope
+}
+
+func classifyPath(relPath string, isDir bool) (logicalType, fileRole string) {
+	parts := strings.Split(relPath, "/")
+	name := parts[len(parts)-1]
+	if !isDir {
+		fileRole = strings.TrimSuffix(name, filepath.Ext(name))
+	}
+
+	switch {
+	case relPath == "settings.json":
+		return "tenant", "settings"
+	case relPath == "layout.json":
+		return "tenant", "layout"
+	case len(parts) >= 1 && parts[0] == "catalog":
+		if isDir {
+			if len(parts) == 1 {
+				return "catalog", ""
+			}
+			if len(parts) >= 2 && parts[1] == "packs" {
+				if len(parts) == 2 {
+					return "catalog_packs", ""
+				}
+				if len(parts) == 3 {
+					return "catalog_pack", ""
+				}
+				if len(parts) >= 4 && parts[3] == "entries" {
+					return "catalog_pack_entries", ""
+				}
+				return "catalog_entry", ""
+			}
+			if len(parts) >= 2 && parts[1] == "standalone" {
+				if len(parts) == 2 {
+					return "catalog_standalone", ""
+				}
+				return "catalog_entry", ""
+			}
+		}
+		return "catalog", fileRole
+	case len(parts) >= 2 && parts[0] == "departments" && strings.HasPrefix(parts[1], "department-"):
+		if isDir {
+			if len(parts) == 2 {
+				return "department", ""
+			}
+			if len(parts) == 3 && parts[2] == "teams" {
+				return "department_teams", ""
+			}
+			if len(parts) >= 4 && strings.HasPrefix(parts[3], "team-") {
+				return "team", ""
+			}
+		}
+		if len(parts) >= 4 && strings.HasPrefix(parts[3], "team-") {
+			return "team", fileRole
+		}
+		return "department", fileRole
+	case len(parts) >= 2 && parts[0] == "projects" && strings.HasPrefix(parts[1], "project-"):
+		if isDir {
+			if len(parts) == 2 {
+				return "project", ""
+			}
+			if len(parts) == 3 && parts[2] == "tree" {
+				return "project_tree", ""
+			}
+			if strings.Contains(relPath, "/tree/") || strings.HasSuffix(relPath, "/tree") {
+				if strings.HasPrefix(name, "folder-") {
+					return "folder", ""
+				}
+				if strings.HasPrefix(name, "item-") {
+					return "item", ""
+				}
+			}
+		}
+		if strings.Contains(relPath, "/tree/") {
+			if strings.HasPrefix(parts[len(parts)-2], "item-") {
+				return "item", fileRole
+			}
+			if strings.HasPrefix(parts[len(parts)-2], "folder-") {
+				return "folder", fileRole
+			}
+		}
+		return "project", fileRole
+	case len(parts) >= 1 && parts[0] == "users":
+		if isDir {
+			if len(parts) == 1 {
+				return "users", ""
+			}
+			if len(parts) == 2 && parts[1] == "personals" {
+				return "personals", ""
+			}
+			if len(parts) >= 3 && parts[1] == "personals" && strings.HasPrefix(parts[2], "personal-") {
+				return "personal", ""
+			}
+			if strings.Contains(relPath, "/tree/") || strings.HasSuffix(relPath, "/tree") {
+				if strings.HasPrefix(name, "folder-") {
+					return "folder", ""
+				}
+				if strings.HasPrefix(name, "item-") {
+					return "item", ""
+				}
+			}
+		}
+		if len(parts) >= 3 && parts[1] == "personals" && strings.HasPrefix(parts[2], "personal-") {
+			if strings.Contains(relPath, "/tree/") {
+				if strings.HasPrefix(parts[len(parts)-2], "item-") {
+					return "item", fileRole
+				}
+				if strings.HasPrefix(parts[len(parts)-2], "folder-") {
+					return "folder", fileRole
+				}
+			}
+			return "personal", fileRole
+		}
+		return "users", fileRole
+	default:
+		if isDir {
+			return "directory", ""
+		}
+		return "file", fileRole
+	}
+}
+
+func projectionParentPath(relPath string) *string {
+	if relPath == "" || relPath == rootProjectionPath {
+		return nil
+	}
+	parent := filepath.ToSlash(filepath.Dir(relPath))
+	if parent == "." || parent == "" {
+		root := rootProjectionPath
+		return &root
+	}
+	return &parent
+}
+
+func inferredResourceSlug(logicalType string, scope Scope) string {
+	switch logicalType {
+	case "department":
+		return scope.DepartmentSlug
+	case "team":
+		return scope.TeamSlug
+	case "project":
+		return scope.ProjectSlug
+	case "personal":
+		return scope.PersonalSlug
+	default:
+		return ""
+	}
+}
+
+func parentEntityName(logicalType string, scope Scope) string {
+	switch logicalType {
+	case "department":
+		return scope.DepartmentSlug
+	case "team":
+		return scope.TeamSlug
+	case "project":
+		return scope.ProjectSlug
+	case "personal":
+		return scope.PersonalSlug
+	default:
+		return ""
+	}
+}
+
+func stringValue(value any) string {
+	stringValue, _ := value.(string)
+	return strings.TrimSpace(stringValue)
+}
+
+func firstNonEmpty(values ...string) string {
+	for _, value := range values {
+		trimmed := strings.TrimSpace(value)
+		if trimmed != "" {
+			return trimmed
+		}
+	}
+	return ""
+}
+
+func summarizeNodes(nodes []Node) RebuildSummary {
+	summary := RebuildSummary{TotalNodes: len(nodes)}
+	for _, node := range nodes {
+		switch node.NodeKind {
+		case NodeKindDirectory:
+			summary.DirectoryCount++
+		case NodeKindFile:
+			summary.FileCount++
+		}
+	}
+	return summary
+}
+
+func errorsIsNotExist(err error) bool {
+	return err != nil && os.IsNotExist(err)
+}

Backend/internal/posixproj/projector_test.go

@@ -0,0 +1,148 @@
+package posixproj
+
+import (
+	"encoding/json"
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+func TestScanRootBuildsProjectedNodesFromBootstrapShape(t *testing.T) {
+	root := filepath.Join(t.TempDir(), "POSIX")
+
+	mustMkdirAll(t, filepath.Join(root, "catalog", "packs"))
+	mustMkdirAll(t, filepath.Join(root, "catalog", "standalone"))
+	mustMkdirAll(t, filepath.Join(root, "departments", "department-primary-department", "teams", "team-primary-team"))
+	mustMkdirAll(t, filepath.Join(root, "projects", "project-primary-project", "tree"))
+	mustMkdirAll(t, filepath.Join(root, "users", "personals"))
+
+	mustWriteJSON(t, filepath.Join(root, "settings.json"), map[string]any{
+		"installation": map[string]any{
+			"id":             "installation-1",
+			"name":           "MangoPig",
+			"isBootstrapped": true,
+		},
+		"organization": map[string]any{
+			"id":   "org-1",
+			"name": "Primary Organization",
+			"slug": "primary-organization",
+		},
+	})
+	mustWriteJSON(t, filepath.Join(root, "layout.json"), map[string]any{
+		"type": "tenant-layout",
+		"home": map[string]any{"defaultProjectSlug": "primary-project"},
+	})
+	mustWriteJSON(t, filepath.Join(root, "departments", "department-primary-department", "settings.json"), map[string]any{
+		"id":   "dept-1",
+		"name": "Primary Department",
+		"slug": "primary-department",
+		"type": "department",
+	})
+	mustWriteJSON(t, filepath.Join(root, "departments", "department-primary-department", "users.json"), map[string]any{
+		"users": []map[string]any{{"id": "admin-1"}},
+	})
+	mustWriteJSON(t, filepath.Join(root, "departments", "department-primary-department", "teams", "team-primary-team", "settings.json"), map[string]any{
+		"id":   "team-1",
+		"name": "Primary Team",
+		"slug": "primary-team",
+		"type": "team",
+	})
+	mustWriteJSON(t, filepath.Join(root, "projects", "project-primary-project", "settings.json"), map[string]any{
+		"id":   "project-1",
+		"name": "Primary Project",
+		"slug": "primary-project",
+		"type": "project",
+	})
+	mustWriteJSON(t, filepath.Join(root, "projects", "project-primary-project", "home.json"), map[string]any{
+		"type":    "project-home",
+		"project": "primary-project",
+	})
+	mustWriteJSON(t, filepath.Join(root, "users", "settings.json"), map[string]any{
+		"primaryAdminId": "admin-1",
+	})
+	mustWriteJSON(t, filepath.Join(root, "users", "data.json"), map[string]any{
+		"users": []map[string]any{{"id": "admin-1", "email": "ronald@example.com"}},
+	})
+
+	nodes, err := ScanRoot(root)
+	if err != nil {
+		t.Fatalf("ScanRoot() error = %v", err)
+	}
+
+	index := make(map[string]Node, len(nodes))
+	for _, node := range nodes {
+		index[node.Path] = node
+	}
+
+	rootNode, ok := index[rootProjectionPath]
+	if !ok {
+		t.Fatalf("expected synthetic root node")
+	}
+	if rootNode.LogicalType != "tenant_root" {
+		t.Fatalf("expected root logical type tenant_root, got %q", rootNode.LogicalType)
+	}
+	if rootNode.OrganizationSlug != "primary-organization" {
+		t.Fatalf("expected root organization slug primary-organization, got %q", rootNode.OrganizationSlug)
+	}
+
+	tenantSettings := index["settings.json"]
+	if tenantSettings.LogicalType != "tenant" || tenantSettings.FileRole != "settings" {
+		t.Fatalf("unexpected tenant settings classification: %#v", tenantSettings)
+	}
+	if tenantSettings.InstallationID != "installation-1" {
+		t.Fatalf("expected installation id installation-1, got %q", tenantSettings.InstallationID)
+	}
+
+	deptSettings := index["departments/department-primary-department/settings.json"]
+	if deptSettings.DepartmentSlug != "primary-department" {
+		t.Fatalf("expected department slug primary-department, got %q", deptSettings.DepartmentSlug)
+	}
+	if deptSettings.ResourceID != "dept-1" {
+		t.Fatalf("expected department resource id dept-1, got %q", deptSettings.ResourceID)
+	}
+
+	teamSettings := index["departments/department-primary-department/teams/team-primary-team/settings.json"]
+	if teamSettings.TeamSlug != "primary-team" {
+		t.Fatalf("expected team slug primary-team, got %q", teamSettings.TeamSlug)
+	}
+
+	projectSettings := index["projects/project-primary-project/settings.json"]
+	if projectSettings.ProjectSlug != "primary-project" {
+		t.Fatalf("expected project slug primary-project, got %q", projectSettings.ProjectSlug)
+	}
+	if projectSettings.ResourceName != "Primary Project" {
+		t.Fatalf("expected project resource name Primary Project, got %q", projectSettings.ResourceName)
+	}
+
+	projectTree := index["projects/project-primary-project/tree"]
+	if projectTree.LogicalType != "project_tree" || projectTree.NodeKind != NodeKindDirectory {
+		t.Fatalf("unexpected project tree node: %#v", projectTree)
+	}
+
+	usersData := index["users/data.json"]
+	if usersData.LogicalType != "users" || usersData.FileRole != "data" {
+		t.Fatalf("unexpected users data classification: %#v", usersData)
+	}
+	if usersData.Checksum == "" || usersData.SizeBytes == 0 {
+		t.Fatalf("expected users/data.json checksum and size to be populated: %#v", usersData)
+	}
+}
+
+func mustMkdirAll(t *testing.T, path string) {
+	t.Helper()
+	if err := os.MkdirAll(path, 0o755); err != nil {
+		t.Fatalf("MkdirAll(%q) error = %v", path, err)
+	}
+}
+
+func mustWriteJSON(t *testing.T, path string, payload any) {
+	t.Helper()
+	bytes, err := json.MarshalIndent(payload, "", "  ")
+	if err != nil {
+		t.Fatalf("MarshalIndent(%q) error = %v", path, err)
+	}
+	bytes = append(bytes, '\n')
+	if err := os.WriteFile(path, bytes, 0o644); err != nil {
+		t.Fatalf("WriteFile(%q) error = %v", path, err)
+	}
+}

Commands/Local/Dev/backend.just

@@ -9,18 +9,22 @@ migrate-up:
 migrate-down:
 	cd '{{backend_dir}}' && go run ./cmd/migrate down
 
-# Reset all embedded database migrations and reapply from scratch.
+# Reset all embedded database migrations.
 migrate-reset:
 	cd '{{backend_dir}}' && go run ./cmd/migrate reset
 
+# Reset embedded database migrations and apply them again from scratch.
+migrate-rebuild:
+	cd '{{backend_dir}}' && go run ./cmd/migrate reset && go run ./cmd/migrate up
+
 # Show the embedded database migration status.
 migrate-status:
 	cd '{{backend_dir}}' && go run ./cmd/migrate status
 
+# Rebuild the POSIX-to-DB projection from the current POSIX root.
+posix-rebuild:
+	cd '{{backend_dir}}' && go run ./cmd/posix rebuild
+
 # Format backend Go source files.
 fmt:
 	cd '{{backend_dir}}' && gofmt -w ./cmd ./db ./internal
-
-# Run backend test suite.
-test:
-	cd '{{backend_dir}}' && go test ./...

Commands/Test/backend.just

@@ -0,0 +1,11 @@
+project_root := justfile_directory()
+backend_dir := project_root + "/Backend"
+
+# Run the full backend test suite.
+[default]
+all:
+	cd '{{backend_dir}}' && go test ./...
+
+# Run the isolated POSIX bootstrap smoke test.
+posix-bootstrap:
+	cd '{{backend_dir}}' && go test ./internal/bootstrap -run TestEnsureBootstrapPOSIXSkeletonInitializesEmptyRoot -count=1 -v

Commands/Test/mod.just

@@ -0,0 +1 @@
+mod backend

Docker/docker-compose.local.dev.yaml

@@ -6,6 +6,7 @@ x-backend-service: &backend-service
   environment:
     DATABASE_URL: postgres://moku:moku_dev_password@postgres:5432/moku?sslmode=disable
     VALKEY_URL: redis://valkey:6379/0
+    POSIX_ROOT: /posix
   depends_on:
     postgres:
       condition: service_healthy
@@ -13,6 +14,7 @@ x-backend-service: &backend-service
       condition: service_healthy
   volumes:
     - ../Backend:/app
+    - ../POSIX:/posix
     - moku_work_backend_go_pkg:/go/pkg/mod
     - moku_work_backend_go_build:/root/.cache/go-build
 

Docker/docker-compose.local.prod.yaml

@@ -5,11 +5,14 @@ x-backend-service: &backend-service
   environment:
     DATABASE_URL: postgres://moku:moku_dev_password@postgres:5432/moku?sslmode=disable
     VALKEY_URL: redis://valkey:6379/0
+    POSIX_ROOT: /posix
   depends_on:
     postgres:
       condition: service_healthy
     valkey:
       condition: service_healthy
+  volumes:
+    - ../POSIX:/posix
 
 services:
   postgres:

Documentation/POSIX-Structure.md

@@ -0,0 +1,61 @@
+# POSIX Structure
+
+``` markdown
+Personal or Organization (server)/
+├── settings.json
+├── layout.json
+├── catalog/
+│   ├── packs/
+│   │   └── pack-<slug>/
+│   │       ├── manifest.json
+│   │       └── entries/
+│   │           └── app-<slug>/
+│   │               └── manifest.json
+│   └── standalone/
+│       └── app-<slug>/
+│           └── manifest.json
+├── departments/
+│   └── department-<slug>/
+│       ├── settings.json
+│       ├── users.json
+│       └── teams/
+│           └── team-<slug>/
+│               ├── settings.json
+│               └── users.json
+├── projects/
+│   └── project-<slug>/
+│       ├── settings.json
+│       ├── home.json
+│       └── tree/
+│           ├── item-<slug>/
+│           │   ├── item.json
+│           │   ├── schema.json
+│           │   └── data.json
+│           └── folder-<slug>/
+│               ├── folder.json
+│               └── item-<slug>/
+│                   ├── item.json
+│                   ├── schema.json
+│                   └── data.json
+└── users/
+    ├── settings.json
+    ├── data.json
+    └── personals/
+        └── personal-<slug>/
+            ├── layout.json
+            ├── settings.json
+            ├── home.json
+            └── tree/
+```
+
+## File Responsibilities
+
+- `settings.json` — Metadata and presentation config for the thing, such as display name, icon, description, and simple settings.
+- `layout.json` — Layout configuration for the current server or personal space.
+- `home.json` — Home surface configuration, such as widgets, sections, and how they are arranged.
+- `folder.json` — Metadata for a folder node in a tree.
+- `item.json` — Instance metadata for a created item, including what it is and how it should behave.
+- `schema.json` — The structure expected by that item's data.
+- `data.json` — The actual content or state data for that item.
+- `manifest.json` — Catalog definition metadata, including versioning, description, and capabilities for reusable apps or entries.
+- `users.json` — User membership or assignment data for departments and teams.

Documentation/TODO.md

@@ -4,87 +4,149 @@
 
 ### Version 0.1.0
 
-**Goal:** Barebone frontend with a real backend core.
+**Goal:** Finish the base application shell, auth, and platform foundations.
 
-#### Architecture
+#### Architecture and Delivery
 
-- [ ] Project-Structure
+- [x] Project-Structure
-- [ ] Stack-Decisions
+- [x] Stack-Decisions
-- [ ] Proxy
+- [x] Proxy
-  - [ ] Local-Prod-NGINX-Proxy
+  - [x] Local-Dev-Vite-Proxy
-  - [ ] Static-Frontend-Serving
+  - [x] Local-Prod-NGINX-Proxy
-- [ ] First-Request-Web-Loader
+- [x] First-Request-Web-Loader
-  - [ ] Bootstrap-Document
+  - [x] Bootstrap-Document
-  - [ ] Route-Intent-Handoff
+  - [x] Route-Intent-Handoff
-  - [ ] Tiny-First-Paint-Budget
+  - [x] Tiny-First-Paint-Budget
-- [ ] Dev-and-Prod-Builds
+- [x] Dev-and-Prod-Builds
   - [x] Local-Dev-Just-Commands
   - [x] Local-Dev-Docker-Compose
-  - [ ] Local-Prod-Just-Commands
+  - [x] Local-Prod-Just-Commands
-  - [ ] Local-Prod-Docker-Compose
+  - [x] Local-Prod-Docker-Compose
-  - [ ] Frontend-Production-Dockerfile
+  - [x] Frontend-Production-Dockerfile
-  - [ ] Frontend-docker-bake
+  - [x] Frontend-docker-bake
 
-#### Backend
+#### Backend — Done Foundations
+
+- [x] Bootstrap-Persistence
+  - [x] Installation-Step
+  - [x] Mode-Step
+  - [x] Admin-Step
+  - [x] Structure-Step
+  - [x] Bootstrap-State-Authority
+  - [x] Development-Bootstrap-Reset
+- [x] Base-Schema
+  - [x] Installations
+  - [x] Users
+  - [x] User-Homes
+  - [x] Organizations
+  - [x] Departments
+  - [x] Teams
+  - [x] Projects
+  - [x] Workspaces
+  - [x] Membership-Tables
+- [x] App-Shell-Read-API
+  - [x] App-Shell-State-Endpoint
+  - [x] Bootstrap-Read-Endpoints
+  - [x] Shell-Tree-Hydration
+- [x] Web-Route-Scaffolds
+  - [x] Session-Endpoint-Scaffold
+  - [x] Bootstrap-Endpoint-Scaffold
+  - [x] Current-User-Endpoint-Scaffold
+
+#### Backend — Remaining for 0.1.0
 
 - [ ] Auth
   - [ ] Session-Flow
   - [ ] Login-Logout-Foundation
   - [ ] Authentication
-- [ ] User
+- [ ] Current-User-Implementation
-  - [ ] Base-Model
+- [ ] POSIX-Lite-File-Persistence-Foundation
+  - [ ] Mounted-Storage-Root-Config
+  - [ ] Project-Folder-Creation-On-Backend
+  - [ ] moku.project.json
+  - [ ] Item-Folder-Creation
+  - [ ] item.json
+  - [ ] schema.json
+  - [ ] data.json
+  - [ ] DB-To-Files-Write-Flow
+- [ ] User-and-Workspace-Domain-Readiness
   - [ ] Base-Workspace
-    - [ ] Folders-and-Subfolders
   - [ ] Boards
   - [ ] Dashboard
-- [ ] Organization
-  - [ ] Base-Model
-  - [ ] Access-Rules-and-Membership
-- [ ] Workspace
-  - [ ] Folders-and-Subfolders
 - [ ] API
+  - [ ] Real-Organizations-Read-Endpoint
+  - [ ] Real-Workspaces-Read-Endpoint
+  - [ ] Tree-Mutation-Endpoints
+  - [ ] Project-Creation-Endpoint
 
-#### Frontend
+#### Frontend — Done Foundations
 
 - [x] Foundation
 - [x] Typography
 - [x] Icons
-- [ ] App Shell
+- [x] App-Shell
+  - [x] Left-Rail
+  - [x] Top-Bar
+  - [x] Server-Dock
+  - [x] Department-Selector
+  - [x] Theme-Toggle
+  - [x] Notifications-Menu
+  - [x] Profile-Menu
+- [x] Responsive-Shell
+  - [x] Collapsible-Shell
+  - [x] Mobile-Bottom-Nav
+  - [x] Mobile-Workspace-Browser
+  - [x] Mobile-Workspace-Views
+- [x] Context-Menus
+  - [x] Workspace-Context-Menu
+  - [x] Project-Context-Menu
+- [x] Bootstrap-Workspace-Home
+  - [x] Bootstrap-Wizard
+  - [x] Bootstrap-Step-Submission
+  - [x] App-Shell-Reload-After-Bootstrap
+- [x] Project-Menu
+  - [x] Folders-and-Subfolders
+  - [x] Rooted-From-Department
+  - [x] Long-Press-Drag-and-Drop
+- [x] Workspace-Tree
+  - [x] Folders-and-Subfolders
+  - [x] Long-Press-Drag-and-Drop
+- [x] App-Shell-Hydration
+
+#### Frontend — Remaining for 0.1.0
+
 - [ ] Primitives
   - [ ] Button
   - [ ] IconButton
   - [ ] Input
   - [ ] Surface
-- [ ] Nav-Bar
 - [ ] Workspace-Switching
-- [ ] Workspace-Home
+- [ ] Real-Workspace-Home
+- [ ] Real-Workspace-Tree-Hydration
+- [ ] Create-Project-Flow
+- [ ] Persist-Tree-Mutations
+- [ ] Connect-Tree-Interactions-To-Backend-Data
 
 ### Version 0.2.0
 
-**Goal:** First real work surface.
+**Goal:** Build the plugin app system on top of the base platform. And core app plugins like calendar, board, docs and text channels
-
-- [ ] Table
-- [ ] CVA
-- [ ] Storyboard
-- [ ] Theme-System
-  - [ ] Theme-Registry
-  - [ ] Built-In-Theme-Presets
-  - [ ] Active-Theme-Persistence
-  - [ ] Theme-Switcher
-  - [ ] Theme-JSON-Upload
-  - [ ] Theme-JSON-Import-Validation
-  - [ ] Community-Theme-Readiness
 
 ### Version 0.3.0
 
-**Goal:** Documents and system hardening.
+**Goal:** Communications and Collaboration (Email System, Reminder System, and Live Collaboration on Documents)
-
-- [ ] Document
-- [ ] Accessibility-Rules
-- [ ] Motion-Foundation
 
 ### Version 0.4.0
 
-- [ ] Gantt-Board
+**Goal:** Introduce the POSIX-based file system drive direction with OnlyOffice + S3 blob storage + Per File Versioning
-- [ ] Calendar
+
-- [ ] Timeline
+### Version 0.5.0
+
+**Goal:** File Sharing and Per File Permissions
+
+### Version 0.6.0
+
+**Goal:** Git as a core plugin
+
+### Version 0.7.0
+
+**Goal:** Full Automation System (Extensive)

Env/.env.example

@@ -10,6 +10,7 @@ BACKEND_SHUTDOWN_TIMEOUT=10s
 
 DATABASE_URL=postgres://moku:moku_dev_password@localhost:5432/moku?sslmode=disable
 VALKEY_URL=redis://localhost:6379/0
+POSIX_ROOT=../POSIX
 
 VITE_API_BASE_URL=/v1
 

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

@@ -9,6 +9,15 @@
   justify-items: center;
 }
 
+.rootDragMode {
+	user-select: none;
+	cursor: grabbing;
+}
+
+.rootDragMode .treeItem {
+	cursor: grabbing;
+}
+
 .trigger {
   width: 100%;
   min-width: 0;
@@ -197,6 +206,43 @@
   padding: 0;
 }
 
+.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;
+}
+
+.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);
+}
+
+.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);
+}
+
 .treeItem {
   width: 100%;
   min-width: 0;
@@ -215,20 +261,43 @@
     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;
 }
 
 .treeItem:hover,
 .treeItem:focus-visible {
-  background: var(--color-surface-hover);
+  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);
 }
 
 .treeItemFolder {
   color: var(--color-text);
 }
 
+.treeItemDragging {
+	opacity: 0.45;
+	transform: scale(0.985);
+	box-shadow: none;
+}
+
+.treeItemDropBefore {
+	box-shadow: inset 0 2px 0 color-mix(in srgb, var(--color-accent-strong) 78%, transparent);
+}
+
+.treeItemDropAfter {
+	box-shadow: inset 0 -2px 0 color-mix(in srgb, var(--color-accent-strong) 78%, transparent);
+}
+
+.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);
+}
+
 .folderChevron {
   color: var(--color-text-muted);
   transition: transform 160ms var(--easing-standard);

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

@@ -1,6 +1,6 @@
 // Path: Frontend/src/components/shell/ProjectSelector/ProjectSelector.tsx
 
-import { For, Show, createEffect, createMemo, createSignal, onCleanup, onMount, type JSX } from "solid-js";
+import { For, Show, createEffect, createSignal, onCleanup, onMount, type JSX } from "solid-js";
 import { ChevronDown, ChevronRight, Folder, LayoutGrid } from "../../../lib/icons";
 import { ProjectContextMenu } from "../ProjectContextMenu/ProjectContextMenu";
 import { useAppShellData } from "../data/app-shell.context";
@@ -21,38 +21,503 @@ type ProjectSelectorProps = {
 	onClose: () => void;
 };
 
+type ProjectFolderNode = {
+	kind: "folder";
+	id: string;
+	label: string;
+	meta?: string;
+	children: ProjectTreeNode[];
+};
+
+type ProjectLeafNode = {
+	kind: "project";
+	item: ProjectItem;
+};
+
+type ProjectTreeNode = ProjectFolderNode | ProjectLeafNode;
+
+type PendingProjectFolderDraft = {
+	parentId: string | null;
+	depth: number;
+};
+
+type ProjectDragTarget = {
+	parentId: string | null;
+	index: number;
+	intent: "before" | "after" | "inside";
+	targetNodeId?: string;
+};
+
+type ProjectDragState = {
+	draggedNodeId: string;
+	dropTarget: ProjectDragTarget | null;
+};
+
+type ProjectNodeLocation = {
+	parentId: string | null;
+	index: number;
+	node: ProjectTreeNode;
+};
+
+const LONG_PRESS_MS = 320;
+
+const createProjectFolderId = (): string => `project-folder-${Math.random().toString(36).slice(2, 10)}`;
+
+const getProjectTreeNodeId = (node: ProjectTreeNode): string =>
+	node.kind === "folder" ? node.id : node.item.id;
+
+const buildProjectTree = (items: readonly ProjectItem[]): ProjectTreeNode[] =>
+	items.map((item) => ({
+		kind: "project",
+		item,
+	}));
+
+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 insertProjectFolderNode = (
+	nodes: readonly ProjectTreeNode[],
+	parentId: string | null,
+	folder: ProjectFolderNode,
+): ProjectTreeNode[] => {
+	if (parentId === null) {
+		return [...nodes, folder];
+	}
+
+	return nodes.map((node) => {
+		if (node.kind !== "folder") {
+			return node;
+		}
+
+		if (node.id === parentId) {
+			return {
+				...node,
+				children: [...node.children, folder],
+			};
+		}
+
+		return {
+			...node,
+			children: insertProjectFolderNode(node.children, parentId, folder),
+		};
+	});
+};
+
+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 {
+				...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);
+};
+
+const ProjectFolderDraftRow = (props: {
+	depth: number;
+	value: string;
+	onInput: (value: string) => void;
+	onSubmit: () => void;
+	onCancel: () => void;
+}): JSX.Element => {
+	let inputRef: HTMLInputElement | undefined;
+
+	queueMicrotask(() => inputRef?.focus());
+
+	return (
+		<li>
+			<div class={styles.treeInputRow} style={{ "--tree-depth": String(props.depth) }}>
+				<Folder class={styles.icon} size={18} strokeWidth={2} />
+				<input
+					ref={inputRef}
+					type="text"
+					class={styles.treeInput}
+					value={props.value}
+					placeholder="Folder name"
+					onInput={(event): void => props.onInput(event.currentTarget.value)}
+					onBlur={props.onSubmit}
+					onKeyDown={(event): void => {
+						if (event.key === "Enter") {
+							event.preventDefault();
+							event.currentTarget.blur();
+							return;
+						}
+
+						if (event.key === "Escape") {
+							event.preventDefault();
+							props.onCancel();
+							event.currentTarget.blur();
+						}
+					}}
+				/>
+			</div>
+		</li>
+	);
+};
+
+const ProjectFolderBranch = (props: {
+	nodes: readonly ProjectTreeNode[];
+	depth: number;
+	parentId: string | null;
+	selectedProjectId: string;
+	isFolderCollapsed: (folderId: string) => boolean;
+	onToggleFolder: (folderId: string) => void;
+	onSelectProject: (projectId: string) => void;
+	onOpenFolderMenu: (event: MouseEvent, folder: ProjectFolderNode) => void;
+	onOpenProjectMenu: (event: MouseEvent, item: ProjectItem) => void;
+	onNodePointerDown: (event: PointerEvent, nodeId: string) => void;
+	onNodePointerMove: (event: PointerEvent, parentId: string | null, index: number, node: ProjectTreeNode) => void;
+	pendingFolderDraft: PendingProjectFolderDraft | null;
+	pendingFolderName: string;
+	onPendingFolderNameChange: (value: string) => void;
+	onSubmitPendingFolder: () => void;
+	onCancelPendingFolder: () => void;
+	dragState: ProjectDragState | null;
+}): JSX.Element => (
+	<ul class={styles.treeList} role="list">
+		<Show when={props.nodes.length === 0 && props.pendingFolderDraft?.parentId !== props.parentId}>
+			<li>
+				<div class={styles.treeEmptySlot} style={{ "--tree-depth": String(props.depth) }} />
+			</li>
+		</Show>
+
+		<For each={props.nodes}>
+			{(node, indexAccessor): JSX.Element => {
+				const nodeId = (): string => getProjectTreeNodeId(node);
+				const isDraggedNode = (): boolean => props.dragState?.draggedNodeId === nodeId();
+				const dropIntent = (): ProjectDragTarget["intent"] | null => {
+					if (props.dragState?.dropTarget?.targetNodeId !== nodeId()) {
+						return null;
+					}
+
+					return props.dragState.dropTarget.intent;
+				};
+
+				if (node.kind === "folder") {
+					const isCollapsed = (): boolean => props.isFolderCollapsed(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 || suppressNextTreeClick()) {
+										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)
+								}
+							>
+								<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>
+
+							<Show when={!isCollapsed() && (node.children.length > 0 || props.pendingFolderDraft?.parentId === node.id)}>
+								<ProjectFolderBranch
+									nodes={node.children}
+									depth={props.depth + 1}
+									parentId={node.id}
+									selectedProjectId={props.selectedProjectId}
+									isFolderCollapsed={props.isFolderCollapsed}
+									onToggleFolder={props.onToggleFolder}
+									onSelectProject={props.onSelectProject}
+									onOpenFolderMenu={props.onOpenFolderMenu}
+									onOpenProjectMenu={props.onOpenProjectMenu}
+									onNodePointerDown={props.onNodePointerDown}
+									onNodePointerMove={props.onNodePointerMove}
+									pendingFolderDraft={props.pendingFolderDraft}
+									pendingFolderName={props.pendingFolderName}
+									onPendingFolderNameChange={props.onPendingFolderNameChange}
+									onSubmitPendingFolder={props.onSubmitPendingFolder}
+									onCancelPendingFolder={props.onCancelPendingFolder}
+									dragState={props.dragState}
+								/>
+							</Show>
+						</li>
+					);
+				}
+
+				return (
+					<li>
+						<button
+							type="button"
+							classList={{
+								[styles.treeItem]: true,
+								[styles.treeItemActive]: props.selectedProjectId === node.item.id,
+								[styles.treeItemDragging]: isDraggedNode(),
+								[styles.treeItemDropBefore]: dropIntent() === "before",
+								[styles.treeItemDropAfter]: dropIntent() === "after",
+							}}
+							style={{ "--tree-depth": String(props.depth) }}
+							onClick={(): void => {
+								if (props.dragState || suppressNextTreeClick()) {
+									return;
+								}
+
+								props.onSelectProject(node.item.id);
+							}}
+							onContextMenu={(event): void => props.onOpenProjectMenu(event, node.item)}
+							onPointerDown={(event): void => props.onNodePointerDown(event, node.item.id)}
+							onPointerMove={(event): void =>
+								props.onNodePointerMove(event, props.parentId, indexAccessor(), node)
+							}
+							onPointerEnter={(event): void =>
+								props.onNodePointerMove(event, props.parentId, indexAccessor(), node)
+							}
+						>
+							<LayoutGrid class={styles.icon} size={18} strokeWidth={2} />
+							<span class={styles.label}>{node.item.name}</span>
+							<Show when={node.item.meta}>
+								<span class={styles.itemMeta}>{node.item.meta}</span>
+							</Show>
+						</button>
+					</li>
+				);
+			}}
+		</For>
+
+		<Show when={props.pendingFolderDraft?.parentId === props.parentId}>
+			<ProjectFolderDraftRow
+				depth={props.pendingFolderDraft?.depth ?? props.depth}
+				value={props.pendingFolderName}
+				onInput={props.onPendingFolderNameChange}
+				onSubmit={props.onSubmitPendingFolder}
+				onCancel={props.onCancelPendingFolder}
+			/>
+		</Show>
+	</ul>
+);
+
 export const ProjectSelector = (props: ProjectSelectorProps): JSX.Element => {
 	const appShellData = useAppShellData();
 	const [selectedProject, setSelectedProject] = createSignal(appShellData.activeProject());
 	const [drawerTop, setDrawerTop] = createSignal<number>(0);
 	const [collapsedFolderIds, setCollapsedFolderIds] = createSignal<readonly string[]>([]);
+	const [projectTreeNodes, setProjectTreeNodes] = createSignal<ProjectTreeNode[]>(
+		buildProjectTree(appShellData.projectItems()),
+	);
+	const [pendingFolderDraft, setPendingFolderDraft] = createSignal<PendingProjectFolderDraft | null>(null);
+	const [pendingFolderName, setPendingFolderName] = createSignal("");
+	const [dragState, setDragState] = createSignal<ProjectDragState | null>(null);
+	const [suppressNextTreeClick, setSuppressNextTreeClick] = createSignal(false);
 	let rootRef: HTMLDivElement | undefined;
 	let triggerRef: HTMLButtonElement | undefined;
 	let contextMenuRef: HTMLDivElement | undefined;
+	let longPressTimer: number | undefined;
+	let suppressClickTimer: number | undefined;
 	const contextMenu = createProjectContextMenuController();
 
-	const projectFolders = createMemo(() => {
+	const clearLongPressTimer = (): void => {
-		const sections = new Map<string, ProjectItem[]>();
+		if (longPressTimer !== undefined) {
+			window.clearTimeout(longPressTimer);
+			longPressTimer = undefined;
+		}
+	};
 
-		for (const item of appShellData.projectItems()) {
+	const suppressTreeClickTemporarily = (): void => {
-			const key = item.parentLabel || item.groupLabel || "Projects";
+		setSuppressNextTreeClick(true);
-			const existing = sections.get(key);
 
-			if (existing) {
+		if (suppressClickTimer !== undefined) {
-				existing.push(item);
+			window.clearTimeout(suppressClickTimer);
-				continue;
 		}
 
-			sections.set(key, [item]);
+		suppressClickTimer = window.setTimeout(() => {
-		}
+			setSuppressNextTreeClick(false);
-
+			suppressClickTimer = undefined;
-		return Array.from(sections.entries()).map(([label, items]) => ({
+		}, 80);
-			id: label.toLowerCase().replace(/\s+/g, "-"),
+	};
-			label,
-			meta: items[0]?.groupLabel && items[0].groupLabel !== label ? items[0].groupLabel : undefined,
-			items,
-		}));
-	});
 
 	const isFolderCollapsed = (folderId: string): boolean => collapsedFolderIds().includes(folderId);
 
@@ -66,6 +531,14 @@ export const ProjectSelector = (props: ProjectSelectorProps): JSX.Element => {
 		setSelectedProject(appShellData.activeProject());
 	});
 
+	createEffect(() => {
+		setProjectTreeNodes(buildProjectTree(appShellData.projectItems()));
+		setCollapsedFolderIds([]);
+		setPendingFolderDraft(null);
+		setPendingFolderName("");
+		setDragState(null);
+	});
+
 	onMount(() => {
 		if (triggerRef) {
 			const updateDrawerTop = (): void => {
@@ -109,8 +582,39 @@ export const ProjectSelector = (props: ProjectSelectorProps): JSX.Element => {
 			props.onClose();
 		};
 
+		const handlePointerUp = (): void => {
+			clearLongPressTimer();
+
+			const nextDragState = dragState();
+
+			if (!nextDragState?.dropTarget) {
+				if (nextDragState) {
+					suppressTreeClickTemporarily();
+				}
+				setDragState(null);
+				return;
+			}
+
+			suppressTreeClickTemporarily();
+			setProjectTreeNodes((current) =>
+				moveProjectTreeNode(current, nextDragState.draggedNodeId, nextDragState.dropTarget as ProjectDragTarget),
+			);
+			setDragState(null);
+		};
+
 		const handleEscape = (event: KeyboardEvent): void => {
-			if (event.key !== "Escape" || !props.isOpen) {
+			if (event.key !== "Escape") {
+				return;
+			}
+
+			clearLongPressTimer();
+
+			if (dragState()) {
+				setDragState(null);
+				return;
+			}
+
+			if (!props.isOpen) {
 				return;
 			}
 
@@ -119,10 +623,18 @@ export const ProjectSelector = (props: ProjectSelectorProps): JSX.Element => {
 		};
 
 		document.addEventListener("pointerdown", handlePointerDown);
+		window.addEventListener("pointerup", handlePointerUp);
+		window.addEventListener("pointercancel", handlePointerUp);
 		window.addEventListener("keydown", handleEscape);
 
 		onCleanup(() => {
+			clearLongPressTimer();
+			if (suppressClickTimer !== undefined) {
+				window.clearTimeout(suppressClickTimer);
+			}
 			document.removeEventListener("pointerdown", handlePointerDown);
+			window.removeEventListener("pointerup", handlePointerUp);
+			window.removeEventListener("pointercancel", handlePointerUp);
 			window.removeEventListener("keydown", handleEscape);
 		});
 	});
@@ -137,18 +649,74 @@ export const ProjectSelector = (props: ProjectSelectorProps): JSX.Element => {
 	};
 
 	const selectProject = (projectId: string): void => {
-		const nextProject = appShellData.projectItems().find((item): boolean => item.id === projectId);
+		const location = findProjectNodeLocation(projectTreeNodes(), projectId);
 
-		if (!nextProject) {
+		if (!location || location.node.kind !== "project") {
 			return;
 		}
 
-		setSelectedProject({ id: nextProject.id, name: nextProject.name });
+		setSelectedProject({ id: location.node.item.id, name: location.node.item.name });
 		props.onClose();
 	};
 
-	const handleContextActionSelect = (_action: { id: string; label: string }, _target: ProjectMenuTarget): void => {
+	const beginFolderDraft = (parentId: string | null, depth: number): void => {
-		// Initial implementation keeps the project menu aligned with workspace-menu IA.
+		if (parentId) {
+			setCollapsedFolderIds((current) => current.filter((id) => id !== parentId));
+		}
+
+		setPendingFolderName("");
+		setPendingFolderDraft({ parentId, depth });
+	};
+
+	const submitPendingFolder = (): void => {
+		const name = pendingFolderName().trim();
+		const draft = pendingFolderDraft();
+
+		if (!draft) {
+			return;
+		}
+
+		if (!name) {
+			setPendingFolderDraft(null);
+			setPendingFolderName("");
+			return;
+		}
+
+		setProjectTreeNodes((current) =>
+			insertProjectFolderNode(current, draft.parentId, {
+				kind: "folder",
+				id: createProjectFolderId(),
+				label: name,
+				children: [],
+			}),
+		);
+		setPendingFolderDraft(null);
+		setPendingFolderName("");
+	};
+
+	const cancelPendingFolder = (): void => {
+		setPendingFolderDraft(null);
+		setPendingFolderName("");
+	};
+
+	const handleContextActionSelect = (action: { id: string; label: string }, target: ProjectMenuTarget): void => {
+		if (action.id !== "new-folder") {
+			return;
+		}
+
+		switch (target.kind) {
+			case "surface":
+				beginFolderDraft(null, 0);
+				return;
+			case "folder":
+				beginFolderDraft(target.id, (findProjectNodeDepth(projectTreeNodes(), target.id) ?? 0) + 1);
+				return;
+			case "project": {
+				const parentId = findProjectNodeLocation(projectTreeNodes(), target.id)?.parentId ?? null;
+				beginFolderDraft(parentId, parentId ? (findProjectNodeDepth(projectTreeNodes(), parentId) ?? 0) + 1 : 0);
+				return;
+			}
+		}
 	};
 
 	const handleSurfaceContextMenu = (event: MouseEvent): void => {
@@ -156,12 +724,83 @@ export const ProjectSelector = (props: ProjectSelectorProps): JSX.Element => {
 		contextMenu.openMenu(event, createProjectSurfaceTarget("Projects"));
 	};
 
+	const handleNodePointerDown = (event: PointerEvent, nodeId: string): void => {
+		if (event.button !== 0 || pendingFolderDraft()) {
+			return;
+		}
+
+		clearLongPressTimer();
+		longPressTimer = window.setTimeout(() => {
+			suppressTreeClickTemporarily();
+			setDragState({ draggedNodeId: nodeId, dropTarget: null });
+		}, LONG_PRESS_MS);
+	};
+
+	const handleNodePointerMove = (
+		event: PointerEvent,
+		parentId: string | null,
+		index: number,
+		node: ProjectTreeNode,
+	): void => {
+		const nextDragState = dragState();
+
+		if (!nextDragState) {
+			return;
+		}
+
+		if (nextDragState.draggedNodeId === getProjectTreeNodeId(node)) {
+			return;
+		}
+
+		const bounds = event.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,
+		});
+	};
+
 	return (
 		<div
 			ref={rootRef}
 			classList={{
 				[styles.root]: true,
 				[styles.rootCompact]: !!props.compact,
+				[styles.rootDragMode]: !!dragState(),
 			}}
 			style={{
 				"--project-drawer-top": `${drawerTop()}px`,
@@ -226,79 +865,31 @@ export const ProjectSelector = (props: ProjectSelectorProps): JSX.Element => {
 								<div class={styles.treeSectionLabel}>Projects</div>
 							</Show>
 
-							<ul class={styles.treeList} role="list">
+							<ProjectFolderBranch
-								<For each={projectFolders()}>
+								nodes={projectTreeNodes()}
-									{(folder): JSX.Element => {
+								depth={0}
-										const isCollapsed = (): boolean => isFolderCollapsed(folder.id);
+								parentId={null}
-
+								selectedProjectId={selectedProject().id}
-										return (
+								isFolderCollapsed={isFolderCollapsed}
-										<li>
+								onToggleFolder={toggleFolder}
-											<button
+								onSelectProject={selectProject}
-												type="button"
+								onOpenFolderMenu={(event, folder): void => {
-												classList={{
-													[styles.treeItem]: true,
-													[styles.treeItemFolder]: true,
-												}}
-												aria-expanded={!isCollapsed()}
-												onClick={() => toggleFolder(folder.id)}
-												onContextMenu={(event): void => {
 									event.stopPropagation();
 									contextMenu.openMenu(event, createProjectFolderTarget(folder.id, folder.label));
 								}}
-											>
+								onOpenProjectMenu={(event, item): void => {
-												<ChevronRight
-													classList={{
-														[styles.folderChevron]: true,
-														[styles.folderChevronOpen]: !isCollapsed(),
-													}}
-													size={16}
-													strokeWidth={2}
-												/>
-												<Folder class={styles.icon} size={18} strokeWidth={2} />
-												<span class={styles.label}>{folder.label}</span>
-												<Show when={folder.meta}>
-													<span class={styles.itemMeta}>{folder.meta}</span>
-												</Show>
-											</button>
-
-											<Show when={!isCollapsed()}>
-												<ul class={styles.treeList} role="list">
-													<For each={folder.items}>
-														{(item): JSX.Element => {
-															const isSelected = (): boolean => selectedProject().id === item.id;
-
-															return (
-																<li>
-																	<button
-																		type="button"
-																		classList={{
-																			[styles.treeItem]: true,
-																			[styles.treeItemActive]: isSelected(),
-																		}}
-																		style={{ "--tree-depth": "1" }}
-																		onClick={(): void => selectProject(item.id)}
-																		onContextMenu={(event): void => {
 									event.stopPropagation();
 									contextMenu.openMenu(event, createProjectTarget(item));
 								}}
-																	>
+								onNodePointerDown={handleNodePointerDown}
-																		<LayoutGrid class={styles.icon} size={18} strokeWidth={2} />
+								onNodePointerMove={handleNodePointerMove}
-																		<span class={styles.label}>{item.name}</span>
+								pendingFolderDraft={pendingFolderDraft()}
-																		<Show when={item.meta}>
+								pendingFolderName={pendingFolderName()}
-																			<span class={styles.itemMeta}>{item.meta}</span>
+								onPendingFolderNameChange={setPendingFolderName}
-																		</Show>
+								onSubmitPendingFolder={submitPendingFolder}
-																	</button>
+								onCancelPendingFolder={cancelPendingFolder}
-																</li>
+								dragState={dragState()}
-															);
+							/>
-														}}
-													</For>
-												</ul>
-											</Show>
-										</li>
-										);
-									}}
-								</For>
-							</ul>
 						</div>
 					</div>
 				</>

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

@@ -12,6 +12,15 @@
   isolation: isolate;
 }
 
+.sidebarDragMode {
+	user-select: none;
+	cursor: grabbing;
+}
+
+.sidebarDragMode .treeItem {
+	cursor: grabbing;
+}
+
 .header {
   display: grid;
   gap: var(--space-3);
@@ -123,6 +132,43 @@
   padding: 0;
 }
 
+.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;
+}
+
+.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);
+}
+
+.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);
+}
+
 .navItem {
   width: 100%;
   min-width: 0;
@@ -141,7 +187,7 @@
   width: 100%;
   min-width: 0;
   display: grid;
-  grid-template-columns: auto minmax(0, 1fr) auto;
+  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));
@@ -156,19 +202,51 @@
     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);
 }
 
 .treeItem:hover,
 .treeItem:focus-visible {
-  background: var(--color-surface-hover);
+  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);
 }
 
 .treeItemFolder {
   color: var(--color-text);
 }
 
+.treeItemDragging {
+	opacity: 0.45;
+	transform: scale(0.985);
+	box-shadow: none;
+}
+
+.treeItemDropBefore {
+	box-shadow: inset 0 2px 0 color-mix(in srgb, var(--color-accent-strong) 78%, transparent);
+}
+
+.treeItemDropAfter {
+	box-shadow: inset 0 -2px 0 color-mix(in srgb, var(--color-accent-strong) 78%, transparent);
+}
+
+.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);
+}
+
+.folderChevron {
+  color: var(--color-text-muted);
+  transition: transform 160ms var(--easing-standard);
+}
+
+.folderChevronOpen {
+  transform: rotate(90deg);
+}
+
 .treeItemActive {
   border-color: var(--color-border);
   background: var(--color-surface);

Frontend/src/components/shell/WorkspaceSidebar/WorkspaceSidebar.tsx

@@ -1,7 +1,7 @@
 // Path: Frontend/src/components/shell/WorkspaceSidebar/WorkspaceSidebar.tsx
 
-import { For, Show, createMemo, createSignal, type JSX } from "solid-js";
+import { For, Show, createEffect, createSignal, onCleanup, onMount, type JSX } from "solid-js";
-import { ChevronLeft, ChevronRight } from "../../../lib/icons";
+import { ChevronLeft, ChevronRight, Folder } from "../../../lib/icons";
 import { useAppShellData } from "../data/app-shell.context";
 import { ProjectSelector } from "../ProjectSelector/ProjectSelector";
 import {
@@ -26,12 +26,276 @@ type WorkspaceSidebarProps = {
 	onToggleRailCollapse: () => void;
 };
 
+type PendingWorkspaceFolderDraft = {
+	parentId: string | null;
+	depth: number;
+};
+
+type WorkspaceDragTarget = {
+	parentId: string | null;
+	index: number;
+	intent: "before" | "after" | "inside";
+	targetNodeId?: string;
+};
+
+type WorkspaceDragState = {
+	draggedNodeId: string;
+	dropTarget: WorkspaceDragTarget | null;
+};
+
+type WorkspaceNodeLocation = {
+	parentId: string | null;
+	index: number;
+	node: WorkspaceTreeNode;
+};
+
+const LONG_PRESS_MS = 320;
+
+const createWorkspaceFolderId = (): string => `folder-${Math.random().toString(36).slice(2, 10)}`;
+
+const getWorkspaceTreeNodeId = (node: WorkspaceTreeNode): string => node.id;
+
+const insertWorkspaceFolderNode = (
+	nodes: readonly WorkspaceTreeNode[],
+	parentId: string | null,
+	folder: WorkspaceTreeNode,
+): readonly WorkspaceTreeNode[] => {
+	if (parentId === null) {
+		return [...nodes, folder];
+	}
+
+	return nodes.map((node) => {
+		if (node.kind !== "folder") {
+			return node;
+		}
+
+		if (node.id === parentId) {
+			return {
+				...node,
+				children: [...(node.children ?? []), folder],
+			};
+		}
+
+		return {
+			...node,
+			children: node.children ? insertWorkspaceFolderNode(node.children, parentId, folder) : node.children,
+		};
+	});
+};
+
+const findWorkspaceFolderDepth = (nodes: readonly WorkspaceTreeNode[], folderId: string, depth = 0): number | null => {
+	for (const node of nodes) {
+		if (node.kind !== "folder") {
+			continue;
+		}
+
+		if (node.id === folderId) {
+			return depth;
+		}
+
+		const nestedDepth = node.children ? findWorkspaceFolderDepth(node.children, folderId, depth + 1) : null;
+		if (nestedDepth !== null) {
+			return nestedDepth;
+		}
+	}
+
+	return null;
+};
+
+const findWorkspaceNodeLocation = (
+	nodes: readonly WorkspaceTreeNode[],
+	nodeId: string,
+	parentId: string | null = null,
+): WorkspaceNodeLocation | null => {
+	for (let index = 0; index < nodes.length; index += 1) {
+		const node = nodes[index];
+
+		if (node.id === nodeId) {
+			return { parentId, index, node };
+		}
+
+		if (node.kind === "folder" && node.children) {
+			const nestedLocation = findWorkspaceNodeLocation(node.children, nodeId, node.id);
+
+			if (nestedLocation) {
+				return nestedLocation;
+			}
+		}
+	}
+
+	return null;
+};
+
+const workspaceTreeContainsNode = (nodes: readonly WorkspaceTreeNode[], nodeId: string): boolean => {
+	for (const node of nodes) {
+		if (node.id === nodeId) {
+			return true;
+		}
+
+		if (node.kind === "folder" && node.children && workspaceTreeContainsNode(node.children, nodeId)) {
+			return true;
+		}
+	}
+
+	return false;
+};
+
+const removeWorkspaceTreeNode = (
+	nodes: readonly WorkspaceTreeNode[],
+	nodeId: string,
+): { nodes: WorkspaceTreeNode[]; removed: WorkspaceTreeNode | null } => {
+	const nextNodes: WorkspaceTreeNode[] = [];
+	let removed: WorkspaceTreeNode | null = null;
+
+	for (const node of nodes) {
+		if (node.id === nodeId) {
+			removed = node;
+			continue;
+		}
+
+		if (node.kind === "folder" && node.children) {
+			const result = removeWorkspaceTreeNode(node.children, nodeId);
+
+			if (result.removed) {
+				removed = result.removed;
+				nextNodes.push({
+					...node,
+					children: result.nodes,
+				});
+				continue;
+			}
+		}
+
+		nextNodes.push(node);
+	}
+
+	return { nodes: nextNodes, removed };
+};
+
+const insertWorkspaceTreeNode = (
+	nodes: readonly WorkspaceTreeNode[],
+	parentId: string | null,
+	index: number,
+	nodeToInsert: WorkspaceTreeNode,
+): WorkspaceTreeNode[] => {
+	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 {
+				...node,
+				children: nextChildren,
+			};
+		}
+
+		return {
+			...node,
+			children: node.children ? insertWorkspaceTreeNode(node.children, parentId, index, nodeToInsert) : node.children,
+		};
+	});
+};
+
+const moveWorkspaceTreeNode = (
+	nodes: readonly WorkspaceTreeNode[],
+	draggedNodeId: string,
+	dropTarget: WorkspaceDragTarget,
+): WorkspaceTreeNode[] => {
+	const location = findWorkspaceNodeLocation(nodes, draggedNodeId);
+
+	if (!location) {
+		return [...nodes];
+	}
+
+	if (
+		location.node.kind === "folder" &&
+		dropTarget.parentId !== null &&
+		((location.node.children && workspaceTreeContainsNode(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 = removeWorkspaceTreeNode(nodes, draggedNodeId);
+
+	if (!removalResult.removed) {
+		return [...nodes];
+	}
+
+	return insertWorkspaceTreeNode(removalResult.nodes, dropTarget.parentId, normalizedIndex, removalResult.removed);
+};
+
+const FolderDraftRow = (props: {
+	depth: number;
+	value: string;
+	onInput: (value: string) => void;
+	onSubmit: () => void;
+	onCancel: () => void;
+}): JSX.Element => {
+	let inputRef: HTMLInputElement | undefined;
+
+	queueMicrotask(() => inputRef?.focus());
+
+	return (
+		<li>
+			<div class={styles.treeInputRow} style={{ "--tree-depth": String(props.depth) }}>
+				<Folder class={styles.icon} size={18} strokeWidth={2} />
+				<input
+					ref={inputRef}
+					type="text"
+					class={styles.treeInput}
+					value={props.value}
+					placeholder="Folder name"
+					onInput={(event): void => props.onInput(event.currentTarget.value)}
+					onBlur={props.onSubmit}
+					onKeyDown={(event): void => {
+						if (event.key === "Enter") {
+							event.preventDefault();
+							event.currentTarget.blur();
+							return;
+						}
+
+						if (event.key === "Escape") {
+							event.preventDefault();
+							props.onCancel();
+							event.currentTarget.blur();
+						}
+					}}
+				/>
+			</div>
+		</li>
+	);
+};
+
 const isContextMenuKeyboardTrigger = (event: KeyboardEvent): boolean => event.key === "ContextMenu" || (event.shiftKey && event.key === "F10");
 
 const WorkspaceHomeEntry = (props: {
 	item: WorkspaceStaticItem;
 	onOpenContextMenu: (event: MouseEvent, target: WorkspaceContextMenuTarget) => void;
 	onOpenContextMenuFromKeyboard: (element: HTMLElement, target: WorkspaceContextMenuTarget) => void;
+	onNodePointerDown: (event: PointerEvent, nodeId: string) => void;
+	onNodePointerMove: (event: PointerEvent, parentId: string | null, index: number, node: WorkspaceTreeNode) => void;
+	dragState: WorkspaceDragState | null;
+	isTreeClickSuppressed: () => boolean;
 }): JSX.Element => {
 	const Icon = props.item.icon;
 	const target = createWorkspaceStaticTarget(props.item);
@@ -75,18 +339,41 @@ const WorkspaceHomeEntry = (props: {
 
 const WorkspaceTreeBranch = (props: {
 	nodes: readonly WorkspaceTreeNode[];
+	parentId?: string | null;
 	depth?: number;
+	isFolderCollapsed: (folderId: string) => boolean;
+	onToggleFolder: (folderId: string) => void;
+	pendingFolderDraft: PendingWorkspaceFolderDraft | null;
+	pendingFolderName: string;
+	onPendingFolderNameChange: (value: string) => void;
+	onSubmitPendingFolder: () => void;
+	onCancelPendingFolder: () => void;
 	onOpenContextMenu: (event: MouseEvent, target: WorkspaceContextMenuTarget) => void;
 	onOpenContextMenuFromKeyboard: (element: HTMLElement, target: WorkspaceContextMenuTarget) => void;
 }): JSX.Element => {
 	const depth = () => props.depth ?? 0;
+	const parentId = () => props.parentId ?? null;
 
 	return (
 		<ul class={styles.treeList} role="list">
+		<Show when={props.nodes.length === 0 && props.pendingFolderDraft?.parentId !== parentId()}>
+			<li>
+				<div class={styles.treeEmptySlot} style={{ "--tree-depth": String(depth()) }} />
+			</li>
+		</Show>
 			<For each={props.nodes}>
-				{(node): JSX.Element => {
+				{(node, indexAccessor): JSX.Element => {
 					const Icon = getWorkspaceNodeIcon(node);
 					const target = createWorkspaceTreeTarget(node);
+					const isCollapsed = (): boolean => (node.kind === "folder" ? props.isFolderCollapsed(node.id) : false);
+					const isDraggedNode = (): boolean => props.dragState?.draggedNodeId === node.id;
+					const dropIntent = (): WorkspaceDragTarget["intent"] | null => {
+						if (props.dragState?.dropTarget?.targetNodeId !== node.id) {
+							return null;
+						}
+
+						return props.dragState.dropTarget.intent;
+					};
 
 					return (
 						<li>
@@ -96,8 +383,13 @@ const WorkspaceTreeBranch = (props: {
 									[styles.treeItem]: true,
 									[styles.treeItemActive]: !!node.active,
 									[styles.treeItemFolder]: node.kind === "folder",
+									[styles.treeItemDragging]: isDraggedNode(),
+									[styles.treeItemDropBefore]: dropIntent() === "before",
+									[styles.treeItemDropAfter]: dropIntent() === "after",
+									[styles.treeItemDropInside]: dropIntent() === "inside",
 								}}
 								style={{ "--tree-depth": String(depth()) }}
+								aria-expanded={node.kind === "folder" ? !isCollapsed() : undefined}
 								aria-current={node.active ? "page" : undefined}
 								aria-label={node.label}
 								title={node.label}
@@ -105,10 +397,28 @@ const WorkspaceTreeBranch = (props: {
 								data-kind={node.kind}
 								data-item-type={node.kind === "item" ? node.itemType : undefined}
 								data-active={node.active ? "true" : "false"}
+								onClick={(): void => {
+									if (props.dragState || props.isTreeClickSuppressed()) {
+										return;
+									}
+
+									if (node.kind !== "folder") {
+										return;
+									}
+
+									props.onToggleFolder(node.id);
+								}}
 								onContextMenu={(event): void => {
 									event.stopPropagation();
 									props.onOpenContextMenu(event, target);
 								}}
+								onPointerDown={(event): void => props.onNodePointerDown(event, node.id)}
+								onPointerMove={(event): void =>
+									props.onNodePointerMove(event, parentId(), indexAccessor(), node)
+								}
+								onPointerEnter={(event): void =>
+									props.onNodePointerMove(event, parentId(), indexAccessor(), node)
+								}
 								onKeyDown={(event): void => {
 									if (!isContextMenuKeyboardTrigger(event)) {
 										return;
@@ -118,6 +428,16 @@ const WorkspaceTreeBranch = (props: {
 									props.onOpenContextMenuFromKeyboard(event.currentTarget, target);
 								}}
 							>
+								<Show when={node.kind === "folder"}>
+									<ChevronRight
+										classList={{
+											[styles.folderChevron]: true,
+											[styles.folderChevronOpen]: !isCollapsed(),
+										}}
+										size={16}
+										strokeWidth={2}
+									/>
+								</Show>
 								<Icon class={styles.icon} size={18} strokeWidth={2} />
 								<span class={styles.label}>{node.label}</span>
 								<Show when={node.meta}>
@@ -125,18 +445,40 @@ const WorkspaceTreeBranch = (props: {
 								</Show>
 							</button>
 
-							<Show when={node.children?.length}>
+							<Show when={node.kind === "folder" && !isCollapsed() && (((node.children?.length ?? 0) > 0) || props.pendingFolderDraft?.parentId === node.id)}>
 								<WorkspaceTreeBranch
 									nodes={node.children ?? []}
+									parentId={node.id}
 									depth={depth() + 1}
+									isFolderCollapsed={props.isFolderCollapsed}
+									onToggleFolder={props.onToggleFolder}
+									pendingFolderDraft={props.pendingFolderDraft}
+									pendingFolderName={props.pendingFolderName}
+									onPendingFolderNameChange={props.onPendingFolderNameChange}
+									onSubmitPendingFolder={props.onSubmitPendingFolder}
+									onCancelPendingFolder={props.onCancelPendingFolder}
 									onOpenContextMenu={props.onOpenContextMenu}
 									onOpenContextMenuFromKeyboard={props.onOpenContextMenuFromKeyboard}
+									onNodePointerDown={props.onNodePointerDown}
+									onNodePointerMove={props.onNodePointerMove}
+									dragState={props.dragState}
+									isTreeClickSuppressed={props.isTreeClickSuppressed}
 								/>
 							</Show>
 						</li>
 					);
 				}}
 			</For>
+
+			<Show when={props.pendingFolderDraft && props.pendingFolderDraft.parentId === parentId()}>
+				<FolderDraftRow
+					depth={props.pendingFolderDraft?.depth ?? depth()}
+					value={props.pendingFolderName}
+					onInput={props.onPendingFolderNameChange}
+					onSubmit={props.onSubmitPendingFolder}
+					onCancel={props.onCancelPendingFolder}
+				/>
+			</Show>
 		</ul>
 	);
 };
@@ -144,23 +486,209 @@ const WorkspaceTreeBranch = (props: {
 export const WorkspaceSidebar = (props: WorkspaceSidebarProps): JSX.Element => {
 	const appShellData = useAppShellData();
 	const [isProjectDrawerOpen, setIsProjectDrawerOpen] = createSignal(false);
+	const [workspaceTreeNodes, setWorkspaceTreeNodes] = createSignal<readonly WorkspaceTreeNode[]>(appShellData.workspaceTree());
+	const [collapsedFolderIds, setCollapsedFolderIds] = createSignal<readonly string[]>([]);
+	const [pendingFolderDraft, setPendingFolderDraft] = createSignal<PendingWorkspaceFolderDraft | null>(null);
+	const [pendingFolderName, setPendingFolderName] = createSignal("");
+	const [dragState, setDragState] = createSignal<WorkspaceDragState | null>(null);
+	const [suppressNextTreeClick, setSuppressNextTreeClick] = createSignal(false);
 	const contextMenu = createWorkspaceContextMenuController();
+	let longPressTimer: number | undefined;
+	let suppressClickTimer: number | undefined;
 	const railToggleLabel = (): string => (props.railCollapsed ? "Expand server rail" : "Collapse server rail");
-	const sidebarContextMenuTarget = createMemo(() => createWorkspaceSurfaceTarget(appShellData.activeProject()));
+	const sidebarContextMenuTarget = createWorkspaceSurfaceTarget(appShellData.activeProject());
-	const contextMenuTarget = createMemo(() => contextMenu.menuState()?.target ?? null);
+	const isFolderCollapsed = (folderId: string): boolean => collapsedFolderIds().includes(folderId);
-	const contextMenuPosition = createMemo(() => {
+	const toggleFolder = (folderId: string): void => {
-		const state = contextMenu.menuState();
+		setCollapsedFolderIds((current) =>
-
+			current.includes(folderId) ? current.filter((id) => id !== folderId) : [...current, folderId],
-		return state
+		);
-			? {
+	};
-				x: state.x,
+	const clearLongPressTimer = (): void => {
-				y: state.y,
+		if (longPressTimer !== undefined) {
+			window.clearTimeout(longPressTimer);
+			longPressTimer = undefined;
 		}
-			: null;
+	};
+	const suppressTreeClickTemporarily = (): void => {
+		setSuppressNextTreeClick(true);
+
+		if (suppressClickTimer !== undefined) {
+			window.clearTimeout(suppressClickTimer);
+		}
+
+		suppressClickTimer = window.setTimeout(() => {
+			setSuppressNextTreeClick(false);
+			suppressClickTimer = undefined;
+		}, 80);
+	};
+
+	createEffect(() => {
+		setWorkspaceTreeNodes(appShellData.workspaceTree());
+		setCollapsedFolderIds([]);
+		setPendingFolderDraft(null);
+		setPendingFolderName("");
+		setDragState(null);
 	});
 
-	const handleContextActionSelect = (_action: WorkspaceContextMenuAction, _target: WorkspaceContextMenuTarget): void => {
+	onMount(() => {
-		// Initial implementation only establishes the menu IA and placement.
+		const handlePointerUp = (): void => {
+			clearLongPressTimer();
+
+			const nextDragState = dragState();
+
+			if (!nextDragState?.dropTarget) {
+				if (nextDragState) {
+					suppressTreeClickTemporarily();
+				}
+				setDragState(null);
+				return;
+			}
+
+			suppressTreeClickTemporarily();
+			setWorkspaceTreeNodes((current) =>
+				moveWorkspaceTreeNode(current, nextDragState.draggedNodeId, nextDragState.dropTarget as WorkspaceDragTarget),
+			);
+			setDragState(null);
+		};
+
+		const handleEscape = (event: KeyboardEvent): void => {
+			if (event.key !== "Escape") {
+				return;
+			}
+
+			clearLongPressTimer();
+
+			if (dragState()) {
+				setDragState(null);
+			}
+		};
+
+		window.addEventListener("pointerup", handlePointerUp);
+		window.addEventListener("pointercancel", handlePointerUp);
+		window.addEventListener("keydown", handleEscape);
+
+		onCleanup(() => {
+			clearLongPressTimer();
+			if (suppressClickTimer !== undefined) {
+				window.clearTimeout(suppressClickTimer);
+			}
+			window.removeEventListener("pointerup", handlePointerUp);
+			window.removeEventListener("pointercancel", handlePointerUp);
+			window.removeEventListener("keydown", handleEscape);
+		});
+	});
+
+	const beginFolderDraft = (parentId: string | null, depth: number): void => {
+		if (parentId) {
+			setCollapsedFolderIds((current) => current.filter((id) => id !== parentId));
+		}
+
+		setPendingFolderName("");
+		setPendingFolderDraft({ parentId, depth });
+	};
+
+	const submitPendingFolder = (): void => {
+		const name = pendingFolderName().trim();
+		const draft = pendingFolderDraft();
+
+		if (!draft) {
+			return;
+		}
+
+		if (!name) {
+			setPendingFolderDraft(null);
+			setPendingFolderName("");
+			return;
+		}
+
+		setWorkspaceTreeNodes((current) =>
+			insertWorkspaceFolderNode(current, draft.parentId, {
+				id: createWorkspaceFolderId(),
+				label: name,
+				kind: "folder",
+				icon: Folder,
+				children: [],
+			}),
+		);
+		setPendingFolderDraft(null);
+		setPendingFolderName("");
+	};
+
+	const cancelPendingFolder = (): void => {
+		setPendingFolderDraft(null);
+		setPendingFolderName("");
+	};
+
+	const handleNodePointerDown = (event: PointerEvent, nodeId: string): void => {
+		if (event.button !== 0 || pendingFolderDraft()) {
+			return;
+		}
+
+		clearLongPressTimer();
+		longPressTimer = window.setTimeout(() => {
+			suppressTreeClickTemporarily();
+			setDragState({ draggedNodeId: nodeId, dropTarget: null });
+		}, LONG_PRESS_MS);
+	};
+
+	const handleNodePointerMove = (
+		event: PointerEvent,
+		parentId: string | null,
+		index: number,
+		node: WorkspaceTreeNode,
+	): void => {
+		const nextDragState = dragState();
+
+		if (!nextDragState || nextDragState.draggedNodeId === getWorkspaceTreeNodeId(node)) {
+			return;
+		}
+
+		const bounds = event.currentTarget.getBoundingClientRect();
+		const relativeY = bounds.height <= 0 ? 0.5 : (event.clientY - bounds.top) / bounds.height;
+		let nextTarget: WorkspaceDragTarget;
+
+		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.id,
+			};
+		}
+
+		setDragState({ ...nextDragState, dropTarget: nextTarget });
+	};
+
+	const handleContextActionSelect = (action: WorkspaceContextMenuAction, target: WorkspaceContextMenuTarget): void => {
+		if (action.id !== "new-folder") {
+			return;
+		}
+
+		switch (target.kind) {
+			case "workspace":
+			case "home":
+				beginFolderDraft(null, 0);
+				return;
+			case "folder":
+				beginFolderDraft(target.id, (findWorkspaceFolderDepth(workspaceTreeNodes(), target.id) ?? 0) + 1);
+				return;
+			case "settings":
+			case "item":
+				return;
+		}
 	};
 
 	return (
@@ -169,12 +697,13 @@ export const WorkspaceSidebar = (props: WorkspaceSidebarProps): JSX.Element => {
 				classList={{
 					[styles.sidebar]: true,
 					[styles.sidebarCollapsed]: props.collapsed,
+					[styles.sidebarDragMode]: !!dragState(),
 				}}
 				aria-label="Left workspace sidebar"
 				data-ui="workspace-sidebar"
 				data-collapsed={props.collapsed ? "true" : "false"}
 				onContextMenu={(event): void => {
-					contextMenu.openMenu(event, sidebarContextMenuTarget());
+					contextMenu.openMenu(event, sidebarContextMenuTarget);
 				}}
 			>
 				<div
@@ -256,9 +785,21 @@ export const WorkspaceSidebar = (props: WorkspaceSidebarProps): JSX.Element => {
 
 						<div data-slot="workspace-tree-root">
 							<WorkspaceTreeBranch
-							nodes={appShellData.workspaceTree()}
+								nodes={workspaceTreeNodes()}
+								parentId={null}
+								isFolderCollapsed={isFolderCollapsed}
+								onToggleFolder={toggleFolder}
+								pendingFolderDraft={pendingFolderDraft()}
+								pendingFolderName={pendingFolderName()}
+								onPendingFolderNameChange={setPendingFolderName}
+								onSubmitPendingFolder={submitPendingFolder}
+								onCancelPendingFolder={cancelPendingFolder}
 								onOpenContextMenu={contextMenu.openMenu}
 								onOpenContextMenuFromKeyboard={contextMenu.openMenuFromElement}
+								onNodePointerDown={handleNodePointerDown}
+								onNodePointerMove={handleNodePointerMove}
+								dragState={dragState()}
+								isTreeClickSuppressed={suppressNextTreeClick}
 							/>
 						</div>
 					</div>
@@ -266,8 +807,16 @@ export const WorkspaceSidebar = (props: WorkspaceSidebarProps): JSX.Element => {
 			</aside>
 
 			<WorkspaceContextMenu
-				target={contextMenuTarget()}
+				target={contextMenu.menuState()?.target ?? null}
-				position={contextMenuPosition()}
+				position={(() => {
+					const state = contextMenu.menuState();
+					return state
+						? {
+							x: state.x,
+							y: state.y,
+						}
+						: null;
+				})()}
 				menuRef={contextMenu.setMenuRef}
 				onClose={contextMenu.closeMenu}
 				onSelect={handleContextActionSelect}

Justfile

@@ -1,6 +1,7 @@
 set shell := ["bash", "-cu"]
 
 mod local "Commands/Local"
+mod test "Commands/Test"
 
 [default]
 help: