Implemented admin pane + user permission

internal/access/access.go

@@ -1,32 +1,114 @@
-// Package access implements uopi's global user-access policy: every user is
-// trusted (full write) by default, while a configured blacklist can downgrade
-// specific users to read-only or no access. It also resolves the per-request
-// user identity and the user→group memberships defined in config.
+// Package access implements uopi's role-based access policy. Access is granted
+// through group memberships: every user belongs implicitly to the built-in
+// "public" group (granting the baseline viewer role), and may additionally be
+// assigned a higher role in any number of named groups. Roles form a cumulative
+// ladder — viewer < operator < logic-editor < auditor < admin — where each level
+// includes all powers below it. A user's effective capability is the highest
+// role they hold across all their groups.
 //
-// This is the foundation layer (Phase 1). Per-panel ownership/ACL evaluation is
-// layered on top of this in a later phase.
+// Groups can be nested: a member of a parent group holds that role on every
+// descendant group too (unless the descendant assigns them a different role),
+// so an admin of an organisation group administers its sub-teams.
+//
+// As a bootstrap convenience, a policy with no role assignments at all is treated
+// as fully open (everyone is admin), matching an unconfigured/dev deployment.
+// Assigning any role switches to strict mode where unlisted users are viewers.
+//
+// The policy is seeded from the TOML config at startup but is runtime-mutable
+// through the admin pane: once EnablePersistence is called, every mutation is
+// written to a JSON sidecar ({storageDir}/access.json) which, when present on a
+// later startup, becomes the source of truth (the TOML config is then only a
+// bootstrap seed). All access is guarded by an RWMutex and safe for concurrent
+// use; the *Policy pointer is stable so existing shared-pointer wiring is
+// preserved.
 package access
 
 import (
 	"context"
+	"encoding/json"
+	"errors"
+	"os"
+	"path/filepath"
 	"sort"
 	"strings"
+	"sync"
 )
 
-// Level is a global access level. Higher levels include lower ones.
+// PublicGroup is the built-in group every user implicitly belongs to. It cannot
+// be renamed or deleted and is always a top-level (parentless) group.
+const PublicGroup = "public"
+
+// Role is a cumulative access level granted by a group membership. Higher roles
+// include every power of the lower ones.
+type Role int
+
+const (
+	// RoleViewer permits reads only (no signal writes). It is the baseline every
+	// user receives via the public group.
+	RoleViewer Role = iota
+	// RoleOperator adds signal writes (full HMI interaction).
+	RoleOperator
+	// RoleLogic adds editing panel and server-side control logic.
+	RoleLogic
+	// RoleAuditor adds viewing the audit log.
+	RoleAuditor
+	// RoleAdmin adds managing users, groups and access, and viewing server stats.
+	RoleAdmin
+)
+
+// RoleNames lists the role tokens from lowest to highest, for the admin UI.
+var RoleNames = []string{"viewer", "operator", "logiceditor", "auditor", "admin"}
+
+// String renders the role using the tokens accepted by ParseRole.
+func (r Role) String() string {
+	switch r {
+	case RoleOperator:
+		return "operator"
+	case RoleLogic:
+		return "logiceditor"
+	case RoleAuditor:
+		return "auditor"
+	case RoleAdmin:
+		return "admin"
+	default:
+		return "viewer"
+	}
+}
+
+// ParseRole maps a config/JSON token to a Role. Unknown values fall back to the
+// least-privileged viewer.
+func ParseRole(s string) Role {
+	switch strings.ToLower(strings.TrimSpace(s)) {
+	case "operator", "write", "operate", "rw":
+		return RoleOperator
+	case "logiceditor", "logic", "logic_editor", "editor":
+		return RoleLogic
+	case "auditor", "audit":
+		return RoleAuditor
+	case "admin", "administrator":
+		return RoleAdmin
+	default:
+		return RoleViewer
+	}
+}
+
+// Level is a coarse global access level retained for the rest of the codebase
+// (WebSocket auth, middleware, per-panel ACL capping). It is derived from a
+// user's effective role: viewer → read-only, operator and above → write.
 type Level int
 
 const (
-	// LevelNone denies all access.
+	// LevelNone denies all access. Never produced by the role model, but kept so
+	// existing switch statements remain exhaustive.
 	LevelNone Level = iota
-	// LevelRead permits reads only (no create/update/delete/share, no signal writes).
+	// LevelRead permits reads only.
 	LevelRead
-	// LevelWrite permits full access. This is the default for any user not blacklisted.
+	// LevelWrite permits full write access.
 	LevelWrite
 )
 
-// String renders the level using the same tokens accepted by ParseLevel and
-// surfaced to the frontend via /api/v1/me.
+// String renders the level using the tokens surfaced to the frontend via
+// /api/v1/me.
 func (l Level) String() string {
 	switch l {
 	case LevelNone:
@@ -38,88 +120,218 @@ func (l Level) String() string {
 	}
 }
 
-// ParseLevel maps a config string to a Level. Unknown values restrict to
-// read-only, since the only reason to list a user is to limit them.
-func ParseLevel(s string) Level {
-	switch strings.ToLower(strings.TrimSpace(s)) {
-	case "noaccess", "none", "no":
-		return LevelNone
-	case "readonly", "read", "ro":
-		return LevelRead
-	case "write", "readwrite", "rw", "full":
+func roleToLevel(r Role) Level {
+	if r >= RoleOperator {
 		return LevelWrite
-	default:
-		return LevelRead
 	}
+	return LevelRead
 }
 
-// Policy holds the resolved global access configuration. It is immutable after
-// construction and safe for concurrent use.
+// group holds a group's parent (for nesting) and explicit per-user role
+// assignments.
+type group struct {
+	parent  string
+	members map[string]Role
+}
+
+// Policy holds the resolved role-based access configuration. It is safe for
+// concurrent use; reads take a shared lock and admin mutations take an exclusive
+// lock and persist to disk.
 type Policy struct {
-	defaultUser  string
-	blacklist    map[string]Level    // user → downgraded level
-	userGroups   map[string][]string // user → groups they belong to
-	groupNames   []string            // all configured group names (sorted)
-	logicEditors map[string]bool     // users + group names allowed to edit logic
-	auditReaders map[string]bool     // users + group names allowed to view the audit log
+	mu          sync.RWMutex
+	path        string // access.json path; "" disables persistence
+	defaultUser string // immutable after construction/load
+	groups      map[string]*group
 }
 
-// New builds a Policy. blacklist maps a username to a config level string;
-// groups maps a group name to its member usernames. logicEditors optionally
-// restricts who may edit panel/control logic (usernames or group names); empty
-// means no restriction.
-func New(defaultUser string, blacklist map[string]string, groups map[string][]string, logicEditors, auditReaders []string) *Policy {
+// GroupSpec seeds one group at construction time: its name, optional parent, and
+// explicit user→role assignments.
+type GroupSpec struct {
+	Name    string
+	Parent  string
+	Members map[string]Role
+}
+
+// New builds a Policy from group specs. The built-in public group is always
+// created. A spec listing the same user in multiple roles keeps the last one;
+// callers should pass the highest intended role.
+func New(defaultUser string, specs []GroupSpec) *Policy {
 	p := &Policy{
-		defaultUser:  strings.TrimSpace(defaultUser),
-		blacklist:    make(map[string]Level),
-		userGroups:   make(map[string][]string),
-		logicEditors: make(map[string]bool),
-		auditReaders: make(map[string]bool),
+		defaultUser: strings.TrimSpace(defaultUser),
+		groups:      make(map[string]*group),
 	}
-	for _, e := range logicEditors {
-		e = strings.TrimSpace(e)
-		if e != "" {
-			p.logicEditors[e] = true
-		}
-	}
-	for _, e := range auditReaders {
-		e = strings.TrimSpace(e)
-		if e != "" {
-			p.auditReaders[e] = true
-		}
-	}
-	for user, lvl := range blacklist {
-		u := strings.TrimSpace(user)
-		if u == "" {
+	for _, s := range specs {
+		name := strings.TrimSpace(s.Name)
+		if name == "" {
 			continue
 		}
-		p.blacklist[u] = ParseLevel(lvl)
-	}
-	for g, members := range groups {
-		g = strings.TrimSpace(g)
-		if g == "" {
-			continue
-		}
-		p.groupNames = append(p.groupNames, g)
-		for _, m := range members {
-			m = strings.TrimSpace(m)
-			if m == "" {
-				continue
+		g := p.ensureGroupLocked(name)
+		g.parent = strings.TrimSpace(s.Parent)
+		for u, r := range s.Members {
+			if u = strings.TrimSpace(u); u != "" {
+				g.members[u] = r
 			}
-			p.userGroups[m] = append(p.userGroups[m], g)
 		}
 	}
-	sort.Strings(p.groupNames)
+	p.ensureGroupLocked(PublicGroup).parent = ""
+	p.normalizeParentsLocked()
 	return p
 }
 
-// GroupNames returns a copy of every configured user-group name, sorted.
-func (p *Policy) GroupNames() []string {
-	out := make([]string, len(p.groupNames))
-	copy(out, p.groupNames)
-	return out
+// ensureGroupLocked returns the named group, creating an empty one if needed.
+// The caller must hold p.mu for writing (or be in construction).
+func (p *Policy) ensureGroupLocked(name string) *group {
+	g, ok := p.groups[name]
+	if !ok {
+		g = &group{members: make(map[string]Role)}
+		p.groups[name] = g
+	}
+	return g
 }
 
+// normalizeParentsLocked drops parent references to missing groups or that would
+// form a cycle, and forces the public group to be a root.
+func (p *Policy) normalizeParentsLocked() {
+	for name, g := range p.groups {
+		if name == PublicGroup {
+			g.parent = ""
+			continue
+		}
+		if g.parent == "" {
+			continue
+		}
+		if _, ok := p.groups[g.parent]; !ok || p.hasCycleLocked(name) {
+			g.parent = ""
+		}
+	}
+}
+
+// hasCycleLocked reports whether following parent links from start loops back.
+func (p *Policy) hasCycleLocked(start string) bool {
+	seen := make(map[string]bool)
+	for cur := start; cur != ""; {
+		if seen[cur] {
+			return true
+		}
+		seen[cur] = true
+		g, ok := p.groups[cur]
+		if !ok {
+			return false
+		}
+		cur = g.parent
+	}
+	return false
+}
+
+// ── effective role ─────────────────────────────────────────────────────────
+
+// configuredLocked reports whether any explicit role is assigned anywhere. An
+// unconfigured policy is treated as fully open (bootstrap-safe).
+func (p *Policy) configuredLocked() bool {
+	for _, g := range p.groups {
+		if len(g.members) > 0 {
+			return true
+		}
+	}
+	return false
+}
+
+// effectiveRoleLocked returns a user's highest role across all groups. Unlisted
+// users (and anonymous callers) get the viewer baseline once the policy is
+// configured; an unconfigured policy grants everyone admin.
+func (p *Policy) effectiveRoleLocked(user string) Role {
+	if !p.configuredLocked() {
+		return RoleAdmin
+	}
+	best := RoleViewer
+	if user = strings.TrimSpace(user); user == "" {
+		return best
+	}
+	for _, g := range p.groups {
+		if r, ok := g.members[user]; ok && r > best {
+			best = r
+		}
+	}
+	return best
+}
+
+// ── persistence ────────────────────────────────────────────────────────────
+
+// persisted is the on-disk schema for access.json.
+type persisted struct {
+	DefaultUser string                    `json:"defaultUser"`
+	Groups      map[string]persistedGroup `json:"groups"`
+}
+
+type persistedGroup struct {
+	Parent  string            `json:"parent"`
+	Members map[string]string `json:"members"` // user → role token
+}
+
+// EnablePersistence points the policy at {storageDir}/access.json. If the file
+// exists its contents replace the TOML-seeded state (the file is the source of
+// truth once written); otherwise the current state is kept and the file is only
+// created on the first mutation.
+func (p *Policy) EnablePersistence(storageDir string) error {
+	p.mu.Lock()
+	defer p.mu.Unlock()
+	p.path = filepath.Join(storageDir, "access.json")
+	data, err := os.ReadFile(p.path)
+	if errors.Is(err, os.ErrNotExist) {
+		return nil
+	}
+	if err != nil {
+		return err
+	}
+	var ps persisted
+	if err := json.Unmarshal(data, &ps); err != nil {
+		return err
+	}
+	p.defaultUser = strings.TrimSpace(ps.DefaultUser)
+	p.groups = make(map[string]*group)
+	for name, pg := range ps.Groups {
+		if name = strings.TrimSpace(name); name == "" {
+			continue
+		}
+		g := p.ensureGroupLocked(name)
+		g.parent = strings.TrimSpace(pg.Parent)
+		for u, token := range pg.Members {
+			if u = strings.TrimSpace(u); u != "" {
+				g.members[u] = ParseRole(token)
+			}
+		}
+	}
+	p.ensureGroupLocked(PublicGroup).parent = ""
+	p.normalizeParentsLocked()
+	return nil
+}
+
+// saveLocked atomically persists the current state when persistence is enabled.
+func (p *Policy) saveLocked() error {
+	if p.path == "" {
+		return nil
+	}
+	ps := persisted{DefaultUser: p.defaultUser, Groups: make(map[string]persistedGroup, len(p.groups))}
+	for name, g := range p.groups {
+		pg := persistedGroup{Parent: g.parent, Members: make(map[string]string, len(g.members))}
+		for u, r := range g.members {
+			pg.Members[u] = r.String()
+		}
+		ps.Groups[name] = pg
+	}
+	data, err := json.MarshalIndent(ps, "", "  ")
+	if err != nil {
+		return err
+	}
+	tmp := p.path + ".tmp"
+	if err := os.WriteFile(tmp, data, 0o644); err != nil {
+		return err
+	}
+	return os.Rename(tmp, p.path)
+}
+
+// ── reads ──────────────────────────────────────────────────────────────────
+
 // ResolveUser trims the proxy-provided header value and falls back to the
 // configured default_user when it is empty (e.g. unproxied/dev deployments).
 func (p *Policy) ResolveUser(headerValue string) string {
@@ -130,81 +342,335 @@ func (p *Policy) ResolveUser(headerValue string) string {
 	return u
 }
 
-// Level returns the global access level for a user. Users that are neither
-// blacklisted nor anonymous get full write access.
+// Level returns the coarse global access level for a user.
 func (p *Policy) Level(user string) Level {
-	user = strings.TrimSpace(user)
-	if user == "" {
-		// No identity at all (no proxy header, no default_user): trusted LAN.
-		return LevelWrite
-	}
-	if lvl, ok := p.blacklist[user]; ok {
-		return lvl
-	}
-	return LevelWrite
+	p.mu.RLock()
+	defer p.mu.RUnlock()
+	return roleToLevel(p.effectiveRoleLocked(user))
 }
 
-// LogicRestricted reports whether a logic-editor allowlist is configured. When
-// false, any write-capable user may edit panel/control logic.
-func (p *Policy) LogicRestricted() bool {
-	return len(p.logicEditors) > 0
+// EffectiveRole returns the highest role a user holds across all groups.
+func (p *Policy) EffectiveRole(user string) Role {
+	p.mu.RLock()
+	defer p.mu.RUnlock()
+	return p.effectiveRoleLocked(user)
 }
 
-// CanEditLogic reports whether a user may add or edit panel logic and
-// server-side control logic. When no allowlist is configured everyone with
-// write access qualifies; otherwise the user (or one of their groups) must be
-// listed. Anonymous/trusted-LAN callers (user=="") are always permitted.
+// CanEditLogic reports whether a user may add or edit panel and control logic
+// (logic-editor role or higher).
 func (p *Policy) CanEditLogic(user string) bool {
-	user = strings.TrimSpace(user)
-	if user == "" {
-		return true
-	}
-	if !p.LogicRestricted() {
-		return true
-	}
-	if p.logicEditors[user] {
-		return true
-	}
-	for _, g := range p.userGroups[user] {
-		if p.logicEditors[g] {
-			return true
-		}
-	}
-	return false
+	p.mu.RLock()
+	defer p.mu.RUnlock()
+	return p.effectiveRoleLocked(user) >= RoleLogic
 }
 
-// CanViewAudit reports whether a user may view the audit log. When no reader
-// allowlist is configured everyone with read access qualifies; otherwise the
-// user (or one of their groups) must be listed. Anonymous/trusted-LAN callers
-// (user=="") are always permitted.
+// CanViewAudit reports whether a user may view the audit log (auditor or admin).
 func (p *Policy) CanViewAudit(user string) bool {
-	user = strings.TrimSpace(user)
-	if user == "" {
-		return true
-	}
-	if len(p.auditReaders) == 0 {
-		return true
-	}
-	if p.auditReaders[user] {
-		return true
-	}
-	for _, g := range p.userGroups[user] {
-		if p.auditReaders[g] {
-			return true
-		}
-	}
-	return false
+	p.mu.RLock()
+	defer p.mu.RUnlock()
+	return p.effectiveRoleLocked(user) >= RoleAuditor
 }
 
-// GroupsOf returns a copy of the groups a user belongs to.
-func (p *Policy) GroupsOf(user string) []string {
-	src := p.userGroups[strings.TrimSpace(user)]
-	out := make([]string, len(src))
-	copy(out, src)
+// CanAdmin reports whether a user may use the admin pane (admin role).
+func (p *Policy) CanAdmin(user string) bool {
+	p.mu.RLock()
+	defer p.mu.RUnlock()
+	return p.effectiveRoleLocked(user) >= RoleAdmin
+}
+
+// GroupNames returns a copy of every group name, sorted.
+func (p *Policy) GroupNames() []string {
+	p.mu.RLock()
+	defer p.mu.RUnlock()
+	return p.groupNamesLocked()
+}
+
+func (p *Policy) groupNamesLocked() []string {
+	out := make([]string, 0, len(p.groups))
+	for n := range p.groups {
+		out = append(out, n)
+	}
+	sort.Strings(out)
 	return out
 }
 
-// ── request-scoped user identity ────────────────────────────────────────────
+// GroupsOf returns the groups a user effectively belongs to: every group they
+// are an explicit member of, plus that group's descendants (membership flows
+// parent→child). The implicit public-group viewer baseline is not included.
+// Used by per-panel/folder sharing rules.
+func (p *Policy) GroupsOf(user string) []string {
+	p.mu.RLock()
+	defer p.mu.RUnlock()
+	if user = strings.TrimSpace(user); user == "" {
+		return nil
+	}
+	set := make(map[string]bool)
+	for name, g := range p.groups {
+		if _, ok := g.members[user]; ok {
+			set[name] = true
+			p.addDescendantsLocked(name, set)
+		}
+	}
+	out := make([]string, 0, len(set))
+	for n := range set {
+		out = append(out, n)
+	}
+	sort.Strings(out)
+	return out
+}
+
+// addDescendantsLocked adds every transitive child of parent into set.
+func (p *Policy) addDescendantsLocked(parent string, set map[string]bool) {
+	for name, g := range p.groups {
+		if g.parent == parent && !set[name] {
+			set[name] = true
+			p.addDescendantsLocked(name, set)
+		}
+	}
+}
+
+// ── admin snapshot ─────────────────────────────────────────────────────────
+
+// MemberInfo is one user's role within a group.
+type MemberInfo struct {
+	User string `json:"user"`
+	Role string `json:"role"`
+}
+
+// GroupInfo describes one group for the admin pane.
+type GroupInfo struct {
+	Name    string       `json:"name"`
+	Parent  string       `json:"parent"`
+	Members []MemberInfo `json:"members"`
+}
+
+// UserInfo describes one user's memberships and resulting effective role.
+type UserInfo struct {
+	Name          string            `json:"name"`
+	EffectiveRole string            `json:"effectiveRole"`
+	Roles         map[string]string `json:"roles"` // group → role token
+}
+
+// AccessSnapshot is the full mutable access state, rendered for the admin pane.
+type AccessSnapshot struct {
+	DefaultUser string      `json:"defaultUser"`
+	PublicGroup string      `json:"publicGroup"`
+	Roles       []string    `json:"roles"` // role ladder, low→high
+	Configured  bool        `json:"configured"`
+	Users       []UserInfo  `json:"users"`
+	Groups      []GroupInfo `json:"groups"`
+}
+
+// Snapshot returns a copy of the full access configuration for the admin pane.
+func (p *Policy) Snapshot() AccessSnapshot {
+	p.mu.RLock()
+	defer p.mu.RUnlock()
+
+	snap := AccessSnapshot{
+		DefaultUser: p.defaultUser,
+		PublicGroup: PublicGroup,
+		Roles:       append([]string(nil), RoleNames...),
+		Configured:  p.configuredLocked(),
+	}
+
+	userSet := make(map[string]bool)
+	for _, name := range p.groupNamesLocked() {
+		g := p.groups[name]
+		gi := GroupInfo{Name: name, Parent: g.parent}
+		users := make([]string, 0, len(g.members))
+		for u := range g.members {
+			users = append(users, u)
+			userSet[u] = true
+		}
+		sort.Strings(users)
+		for _, u := range users {
+			gi.Members = append(gi.Members, MemberInfo{User: u, Role: g.members[u].String()})
+		}
+		snap.Groups = append(snap.Groups, gi)
+	}
+
+	users := make([]string, 0, len(userSet))
+	for u := range userSet {
+		users = append(users, u)
+	}
+	sort.Strings(users)
+	for _, u := range users {
+		ui := UserInfo{Name: u, EffectiveRole: p.effectiveRoleLocked(u).String(), Roles: make(map[string]string)}
+		for name, g := range p.groups {
+			if r, ok := g.members[u]; ok {
+				ui.Roles[name] = r.String()
+			}
+		}
+		snap.Users = append(snap.Users, ui)
+	}
+	return snap
+}
+
+// ── mutations (admin pane) ─────────────────────────────────────────────────
+
+// ErrNotFound is returned when a named group does not exist.
+var ErrNotFound = errors.New("group not found")
+
+// SetMemberRole assigns a user a role within an existing group.
+func (p *Policy) SetMemberRole(groupName, user string, role Role) error {
+	groupName, user = strings.TrimSpace(groupName), strings.TrimSpace(user)
+	if groupName == "" {
+		return errors.New("empty group name")
+	}
+	if user == "" {
+		return errors.New("empty user")
+	}
+	p.mu.Lock()
+	defer p.mu.Unlock()
+	g, ok := p.groups[groupName]
+	if !ok {
+		return ErrNotFound
+	}
+	g.members[user] = role
+	return p.saveLocked()
+}
+
+// RemoveMember drops a user's explicit role in a group.
+func (p *Policy) RemoveMember(groupName, user string) error {
+	groupName, user = strings.TrimSpace(groupName), strings.TrimSpace(user)
+	p.mu.Lock()
+	defer p.mu.Unlock()
+	g, ok := p.groups[groupName]
+	if !ok {
+		return ErrNotFound
+	}
+	delete(g.members, user)
+	return p.saveLocked()
+}
+
+// SetUserRoles replaces a user's full set of memberships: the user is placed in
+// exactly the listed groups with the given roles and removed from all others.
+// Listed groups that do not exist are created.
+func (p *Policy) SetUserRoles(user string, roles map[string]Role) error {
+	user = strings.TrimSpace(user)
+	if user == "" {
+		return errors.New("empty user")
+	}
+	p.mu.Lock()
+	defer p.mu.Unlock()
+	want := make(map[string]Role, len(roles))
+	for g, r := range roles {
+		if g = strings.TrimSpace(g); g != "" {
+			want[g] = r
+			p.ensureGroupLocked(g)
+		}
+	}
+	for name, g := range p.groups {
+		if r, ok := want[name]; ok {
+			g.members[user] = r
+		} else {
+			delete(g.members, user)
+		}
+	}
+	p.normalizeParentsLocked()
+	return p.saveLocked()
+}
+
+// CreateGroup adds an empty group with an optional parent if it does not exist.
+func (p *Policy) CreateGroup(name, parent string) error {
+	name, parent = strings.TrimSpace(name), strings.TrimSpace(parent)
+	if name == "" {
+		return errors.New("empty group name")
+	}
+	p.mu.Lock()
+	defer p.mu.Unlock()
+	if _, ok := p.groups[name]; ok {
+		return nil
+	}
+	g := p.ensureGroupLocked(name)
+	g.parent = parent
+	p.normalizeParentsLocked()
+	return p.saveLocked()
+}
+
+// SetGroup replaces an existing group's parent and members. The public group's
+// parent is always forced to root.
+func (p *Policy) SetGroup(name, parent string, members map[string]Role) error {
+	name, parent = strings.TrimSpace(name), strings.TrimSpace(parent)
+	if name == "" {
+		return errors.New("empty group name")
+	}
+	p.mu.Lock()
+	defer p.mu.Unlock()
+	g, ok := p.groups[name]
+	if !ok {
+		return ErrNotFound
+	}
+	if name != PublicGroup {
+		g.parent = parent
+	}
+	g.members = make(map[string]Role, len(members))
+	for u, r := range members {
+		if u = strings.TrimSpace(u); u != "" {
+			g.members[u] = r
+		}
+	}
+	p.normalizeParentsLocked()
+	return p.saveLocked()
+}
+
+// RenameGroup renames a group, re-pointing any children at the new name. The
+// public group cannot be renamed.
+func (p *Policy) RenameGroup(oldName, newName string) error {
+	oldName, newName = strings.TrimSpace(oldName), strings.TrimSpace(newName)
+	if oldName == "" || newName == "" {
+		return errors.New("empty group name")
+	}
+	if oldName == PublicGroup {
+		return errors.New("cannot rename the public group")
+	}
+	p.mu.Lock()
+	defer p.mu.Unlock()
+	g, ok := p.groups[oldName]
+	if !ok {
+		return ErrNotFound
+	}
+	if oldName == newName {
+		return nil
+	}
+	if _, exists := p.groups[newName]; exists {
+		return errors.New("group already exists: " + newName)
+	}
+	delete(p.groups, oldName)
+	p.groups[newName] = g
+	for _, other := range p.groups {
+		if other.parent == oldName {
+			other.parent = newName
+		}
+	}
+	return p.saveLocked()
+}
+
+// DeleteGroup removes a group, reparenting its children to the deleted group's
+// parent. The public group cannot be deleted; member users keep other groups.
+func (p *Policy) DeleteGroup(name string) error {
+	name = strings.TrimSpace(name)
+	if name == PublicGroup {
+		return errors.New("cannot delete the public group")
+	}
+	p.mu.Lock()
+	defer p.mu.Unlock()
+	g, ok := p.groups[name]
+	if !ok {
+		return ErrNotFound
+	}
+	parent := g.parent
+	delete(p.groups, name)
+	for _, other := range p.groups {
+		if other.parent == name {
+			other.parent = parent
+		}
+	}
+	p.normalizeParentsLocked()
+	return p.saveLocked()
+}
+
+// ── request-scoped user identity ───────────────────────────────────────────
 
 type ctxKey struct{}
 

internal/access/access_test.go

@@ -1,35 +1,266 @@
 package access
 
-import "testing"
+import (
+	"os"
+	"path/filepath"
+	"sync"
+	"testing"
+)
 
-func TestCanEditLogic(t *testing.T) {
-	groups := map[string][]string{"ops": {"carol"}}
+// spec is a small helper to build a GroupSpec.
+func spec(name, parent string, members map[string]Role) GroupSpec {
+	return GroupSpec{Name: name, Parent: parent, Members: members}
+}
 
-	// No allowlist configured: everyone with write access may edit logic.
-	open := New("", nil, groups, nil, nil)
+func TestUnconfiguredIsOpen(t *testing.T) {
+	// No roles assigned anywhere → fully open (everyone is admin), matching a
+	// fresh/dev deployment.
+	p := New("", nil)
 	for _, u := range []string{"", "alice", "carol"} {
-		if !open.CanEditLogic(u) {
-			t.Errorf("unrestricted: CanEditLogic(%q) = false, want true", u)
+		if !p.CanAdmin(u) {
+			t.Errorf("unconfigured: CanAdmin(%q) = false, want true", u)
 		}
-	}
-	if open.LogicRestricted() {
-		t.Error("LogicRestricted() = true with no allowlist")
-	}
-
-	// Allowlist by username and by group name.
-	p := New("", nil, groups, []string{"alice", "ops"}, nil)
-	if !p.LogicRestricted() {
-		t.Error("LogicRestricted() = false with allowlist set")
-	}
-	cases := map[string]bool{
-		"":      true,  // anonymous / trusted LAN
-		"alice": true,  // listed user
-		"carol": true,  // member of listed group "ops"
-		"bob":   false, // not listed
-	}
-	for u, want := range cases {
-		if got := p.CanEditLogic(u); got != want {
-			t.Errorf("CanEditLogic(%q) = %v, want %v", u, got, want)
+		if p.Level(u) != LevelWrite {
+			t.Errorf("unconfigured: Level(%q) = %v, want write", u, p.Level(u))
 		}
 	}
 }
+
+func TestRoleLadder(t *testing.T) {
+	p := New("", []GroupSpec{
+		spec("public", "", map[string]Role{"adm": RoleAdmin}),
+		spec("ops", "", map[string]Role{
+			"viewer": RoleViewer,
+			"op":     RoleOperator,
+			"logic":  RoleLogic,
+			"aud":    RoleAuditor,
+		}),
+	})
+
+	// Configured now → unlisted users (and anonymous) are viewers (read-only).
+	if p.Level("") != LevelRead {
+		t.Errorf("anonymous Level = %v, want read", p.Level(""))
+	}
+	if p.Level("nobody") != LevelRead {
+		t.Errorf("unlisted Level = %v, want read", p.Level("nobody"))
+	}
+
+	cases := []struct {
+		user      string
+		level     Level
+		editLogic bool
+		audit     bool
+		admin     bool
+	}{
+		{"viewer", LevelRead, false, false, false},
+		{"op", LevelWrite, false, false, false},
+		{"logic", LevelWrite, true, false, false},
+		{"aud", LevelWrite, true, true, false},
+		{"adm", LevelWrite, true, true, true},
+	}
+	for _, c := range cases {
+		if p.Level(c.user) != c.level {
+			t.Errorf("%s: Level = %v, want %v", c.user, p.Level(c.user), c.level)
+		}
+		if p.CanEditLogic(c.user) != c.editLogic {
+			t.Errorf("%s: CanEditLogic = %v, want %v", c.user, p.CanEditLogic(c.user), c.editLogic)
+		}
+		if p.CanViewAudit(c.user) != c.audit {
+			t.Errorf("%s: CanViewAudit = %v, want %v", c.user, p.CanViewAudit(c.user), c.audit)
+		}
+		if p.CanAdmin(c.user) != c.admin {
+			t.Errorf("%s: CanAdmin = %v, want %v", c.user, p.CanAdmin(c.user), c.admin)
+		}
+	}
+}
+
+func TestEffectiveRoleIsMaxAcrossGroups(t *testing.T) {
+	p := New("", []GroupSpec{
+		spec("public", "", map[string]Role{"x": RoleViewer}),
+		spec("a", "", map[string]Role{"x": RoleOperator}),
+		spec("b", "", map[string]Role{"x": RoleAuditor}),
+	})
+	if got := p.EffectiveRole("x"); got != RoleAuditor {
+		t.Errorf("EffectiveRole(x) = %v, want auditor (max across groups)", got)
+	}
+}
+
+func TestNestingInheritsMembership(t *testing.T) {
+	// org → team-a → squad-1. A member of org is effectively in the descendants
+	// too (membership flows parent→child), surfaced via GroupsOf for panel ACLs.
+	p := New("", []GroupSpec{
+		spec("org", "", map[string]Role{"boss": RoleAdmin}),
+		spec("team-a", "org", nil),
+		spec("squad-1", "team-a", nil),
+	})
+	groups := p.GroupsOf("boss")
+	for _, want := range []string{"org", "team-a", "squad-1"} {
+		if !containsStr(groups, want) {
+			t.Errorf("GroupsOf(boss) = %v, missing %q", groups, want)
+		}
+	}
+}
+
+func TestMutationsRoundTrip(t *testing.T) {
+	p := New("", []GroupSpec{
+		spec("public", "", map[string]Role{"root": RoleAdmin}),
+		spec("ops", "", map[string]Role{"carol": RoleOperator}),
+	})
+
+	// Set a user's full membership set: dave operator in ops, admin in eng (new).
+	if err := p.SetUserRoles("dave", map[string]Role{"ops": RoleOperator, "eng": RoleAdmin}); err != nil {
+		t.Fatal(err)
+	}
+	if g := p.GroupsOf("dave"); !containsStr(g, "ops") || !containsStr(g, "eng") {
+		t.Errorf("GroupsOf(dave) = %v, want ops+eng", g)
+	}
+	if !p.CanAdmin("dave") { // admin in eng
+		t.Error("CanAdmin(dave) = false after admin role in eng")
+	}
+
+	// Replacing membership removes dave from ops.
+	if err := p.SetUserRoles("dave", map[string]Role{"eng": RoleAdmin}); err != nil {
+		t.Fatal(err)
+	}
+	if containsStr(p.GroupsOf("dave"), "ops") {
+		t.Error("dave still in ops after membership replaced")
+	}
+
+	// Rename carries dave's admin grant from eng → engineering.
+	if err := p.RenameGroup("eng", "engineering"); err != nil {
+		t.Fatal(err)
+	}
+	if !p.CanAdmin("dave") {
+		t.Error("CanAdmin(dave) = false after eng renamed to engineering")
+	}
+	if !containsStr(p.GroupNames(), "engineering") || containsStr(p.GroupNames(), "eng") {
+		t.Errorf("GroupNames after rename = %v", p.GroupNames())
+	}
+
+	// Delete drops the group; dave loses admin but root (in public) keeps it.
+	if err := p.DeleteGroup("engineering"); err != nil {
+		t.Fatal(err)
+	}
+	if p.CanAdmin("dave") {
+		t.Error("CanAdmin(dave) = true after engineering deleted")
+	}
+	if !p.CanAdmin("root") {
+		t.Error("CanAdmin(root) = false; root grant in public should survive")
+	}
+	if err := p.DeleteGroup("nope"); err != ErrNotFound {
+		t.Errorf("DeleteGroup(nope) = %v, want ErrNotFound", err)
+	}
+}
+
+func TestPublicGroupProtected(t *testing.T) {
+	p := New("", []GroupSpec{spec("public", "", map[string]Role{"a": RoleAdmin})})
+	if err := p.DeleteGroup(PublicGroup); err == nil {
+		t.Error("DeleteGroup(public) = nil, want error")
+	}
+	if err := p.RenameGroup(PublicGroup, "other"); err == nil {
+		t.Error("RenameGroup(public) = nil, want error")
+	}
+	if !containsStr(p.GroupNames(), PublicGroup) {
+		t.Error("public group missing after protected mutations")
+	}
+}
+
+func TestParentCycleRejected(t *testing.T) {
+	p := New("", []GroupSpec{
+		spec("a", "", map[string]Role{"x": RoleViewer}),
+		spec("b", "a", nil),
+	})
+	// Making a's parent b would create a cycle a→b→a; it must be dropped to root.
+	if err := p.SetGroup("a", "b", map[string]Role{"x": RoleViewer}); err != nil {
+		t.Fatal(err)
+	}
+	snap := p.Snapshot()
+	for _, g := range snap.Groups {
+		if g.Name == "a" && g.Parent != "" {
+			t.Errorf("group a parent = %q, want root (cycle should be dropped)", g.Parent)
+		}
+	}
+}
+
+func TestPersistenceRoundTrip(t *testing.T) {
+	dir := t.TempDir()
+
+	p := New("admin", []GroupSpec{
+		spec("public", "", map[string]Role{"alice": RoleLogic}),
+		spec("ops", "", map[string]Role{"carol": RoleAdmin}),
+	})
+	if err := p.EnablePersistence(dir); err != nil {
+		t.Fatal(err)
+	}
+	// A mutation triggers the first write of access.json.
+	if err := p.SetUserRoles("dave", map[string]Role{"ops": RoleOperator}); err != nil {
+		t.Fatal(err)
+	}
+	if _, err := os.Stat(filepath.Join(dir, "access.json")); err != nil {
+		t.Fatalf("access.json not written: %v", err)
+	}
+
+	// A fresh policy loading the same dir should see the persisted state, not the
+	// (different) seed it was constructed with.
+	p2 := New("seed", []GroupSpec{spec("public", "", map[string]Role{"seeduser": RoleViewer})})
+	if err := p2.EnablePersistence(dir); err != nil {
+		t.Fatal(err)
+	}
+	if p2.ResolveUser("") != "admin" {
+		t.Errorf("default user = %q, want admin", p2.ResolveUser(""))
+	}
+	if !p2.CanEditLogic("alice") || p2.CanEditLogic("zed") {
+		t.Error("logic-editor role not persisted")
+	}
+	if !p2.CanAdmin("carol") {
+		t.Error("admin role not persisted")
+	}
+	if !containsStr(p2.GroupsOf("dave"), "ops") {
+		t.Error("dave membership not persisted")
+	}
+	if p2.EffectiveRole("seeduser") != RoleViewer || p2.Level("seeduser") != LevelRead {
+		// seeduser came from the discarded seed; should be an unlisted viewer now.
+		t.Error("persisted state did not supersede the seed")
+	}
+}
+
+func TestConcurrentAccess(t *testing.T) {
+	p := New("", []GroupSpec{
+		spec("public", "", map[string]Role{"root": RoleAdmin}),
+		spec("ops", "", map[string]Role{"carol": RoleOperator}),
+	})
+	if err := p.EnablePersistence(t.TempDir()); err != nil {
+		t.Fatal(err)
+	}
+	var wg sync.WaitGroup
+	for i := 0; i < 8; i++ {
+		wg.Add(2)
+		go func() {
+			defer wg.Done()
+			for j := 0; j < 100; j++ {
+				p.CanAdmin("carol")
+				p.Level("carol")
+				p.GroupsOf("carol")
+				p.Snapshot()
+			}
+		}()
+		go func() {
+			defer wg.Done()
+			for j := 0; j < 100; j++ {
+				p.SetMemberRole("ops", "carol", RoleAuditor)
+				p.SetUserRoles("carol", map[string]Role{"ops": RoleOperator, "eng": RoleAdmin})
+				p.RemoveMember("ops", "carol")
+			}
+		}()
+	}
+	wg.Wait()
+}
+
+func containsStr(xs []string, v string) bool {
+	for _, x := range xs {
+		if x == v {
+			return true
+		}
+	}
+	return false
+}