feat(admin/users): editable member drawer + mailbox & ownership management

Rebuild the /admin/users detail drawer from a read-only profile into an
editable, Office 365-style panel with four sections:

- Username & mail: read-only primary for mailbox users; editable sign-in
  (Authentik-only) for mailbox-less identities; "Create mailbox" provisions
  a Stalwart inbox for an external-login admin
- Aliases: list/add/remove mailbox aliases (Stalwart), domain-scoped
- Role: member/admin toggle with a primary-account lock (owner, mailbox-less
  bootstrap admin, self) and a last-admin guard
- Contact information: display name, first/last name, phone, alternative
  email — mirrored best-effort to Authentik attributes + mailbox name

Ownership transfer: "Make owner" (row menu + drawer) plus an owner-side
"Transfer ownership" picker, gated to tenant admins / platform admins so a
departed owner can be replaced; promotes the target and demotes the prior
owner to admin.

Backend (platform-api): contact fields on User; AuthentikClient.updateUser;
StalwartClient.setMailboxName; UsersService updateTenantMember,
changeMemberPrimaryEmail, list/add/removeMemberAlias, createMailboxForMember,
transferOwnership; new DTOs and tenant-member routes. All mutations audited.

Portal: Nuxt proxies for the new endpoints + extended TenantUserDoc.

services/platform-api/src/users/dto/change-primary-email.dto.ts

@@ -0,0 +1,10 @@
+import { IsEmail, MaxLength } from 'class-validator'
+
+// Change a mailbox-less member's primary email (their Authentik sign-in
+// identity + our User.email). Refused server-side for members who have a
+// Stalwart mailbox — there the primary address IS the inbox.
+export class ChangePrimaryEmailDto {
+  @IsEmail()
+  @MaxLength(200)
+  email!: string
+}

services/platform-api/src/users/dto/create-mailbox.dto.ts

@@ -0,0 +1,19 @@
+import { IsOptional, IsString, Matches, MaxLength } from 'class-validator'
+
+// Provision a Stalwart mailbox for an existing member who doesn't have one yet
+// (e.g. the bootstrap admin who signs in with an external email). The mailbox
+// is `localPart@domain` on one of the tenant's provisioned domains; the
+// member's sign-in identity is left untouched.
+export class CreateMailboxDto {
+  @IsString()
+  @MaxLength(64)
+  @Matches(/^[a-zA-Z0-9._-]+$/, {
+    message: 'address prefix may only contain letters, numbers, dots, hyphens and underscores',
+  })
+  localPart!: string
+
+  // Optional explicit domain (must belong to the tenant); omitted = primary.
+  @IsOptional()
+  @IsString()
+  domain?: string
+}

services/platform-api/src/users/dto/member-alias.dto.ts

@@ -0,0 +1,23 @@
+import { IsEmail, IsString, Matches, MaxLength } from 'class-validator'
+
+// Add an alias address (localPart@domain) that delivers to the member's
+// mailbox. The domain must be one of this tenant's provisioned mail domains.
+export class AddAliasDto {
+  @IsString()
+  @MaxLength(64)
+  @Matches(/^[a-zA-Z0-9._-]+$/, {
+    message: 'alias prefix may only contain letters, numbers, dots, hyphens and underscores',
+  })
+  localPart!: string
+
+  @IsString()
+  @MaxLength(255)
+  domain!: string
+}
+
+// Remove an alias by its full address.
+export class RemoveAliasDto {
+  @IsEmail()
+  @MaxLength(320)
+  address!: string
+}

services/platform-api/src/users/dto/update-tenant-member.dto.ts

@@ -0,0 +1,43 @@
+import { IsEmail, IsIn, IsOptional, IsString, MaxLength, MinLength, ValidateIf } from 'class-validator'
+
+// Patch a workspace member's directory profile + in-tenant role. Every field is
+// optional — the drawer saves contact info and role independently, so a request
+// may carry just one section's worth. Empty strings are allowed (and clear the
+// field) for the free-text fields; alternativeEmail must be a valid email when
+// non-empty.
+export class UpdateTenantMemberDto {
+  @IsOptional()
+  @IsString()
+  @MinLength(1)
+  @MaxLength(120)
+  name?: string
+
+  @IsOptional()
+  @IsString()
+  @MaxLength(80)
+  firstName?: string
+
+  @IsOptional()
+  @IsString()
+  @MaxLength(80)
+  lastName?: string
+
+  @IsOptional()
+  @IsString()
+  @MaxLength(40)
+  phone?: string
+
+  // '' clears it; any other value must look like an email.
+  @IsOptional()
+  @ValidateIf((o) => o.alternativeEmail !== '')
+  @IsEmail()
+  @MaxLength(200)
+  alternativeEmail?: string
+
+  // In-tenant role only. Owner is intentionally excluded — ownership transfer
+  // is a separate, guarded flow; this section never promotes to / demotes from
+  // owner.
+  @IsOptional()
+  @IsIn(['admin', 'member'])
+  role?: 'admin' | 'member'
+}

services/platform-api/src/users/tenant-members.controller.ts

@@ -3,8 +3,10 @@ import {
   Controller,
   Delete,
   ForbiddenException,
+  Get,
   HttpCode,
   Param,
+  Patch,
   Post,
   Req,
   UseGuards,
@@ -15,8 +17,13 @@ import { CurrentUser } from '../auth/current-user.decorator.js'
 import { JwtAuthGuard } from '../auth/jwt-auth.guard.js'
 import type { AuthentikJwtPayload } from '../auth/jwt-payload.interface.js'
 import type { AuditActor } from '../audit/audit.service.js'
+import { roleForTenant } from '../schemas/user.schema.js'
 import { TenantsService } from '../tenants/tenants.service.js'
+import { ChangePrimaryEmailDto } from './dto/change-primary-email.dto.js'
+import { CreateMailboxDto } from './dto/create-mailbox.dto.js'
 import { CreateTenantMemberDto } from './dto/create-tenant-member.dto.js'
+import { AddAliasDto, RemoveAliasDto } from './dto/member-alias.dto.js'
+import { UpdateTenantMemberDto } from './dto/update-tenant-member.dto.js'
 import { UsersService } from './users.service.js'
 
 function auditActor(
@@ -163,4 +170,143 @@ export class TenantMembersController {
       auditActor(actor, req),
     )
   }
+
+  // Update a member's directory profile (display name + contact info) and/or
+  // in-tenant role. Returns the fresh user doc with the tenant-scoped role,
+  // mirroring GET :slug/users so the UI can swap the row in place.
+  @Patch(':userId')
+  async update(
+    @Param('slug') slug: string,
+    @Param('userId') userId: string,
+    @Body() dto: UpdateTenantMemberDto,
+    @CurrentUser() jwt: AuthentikJwtPayload,
+    @Req() req: Parameters<typeof clientIp>[0],
+  ) {
+    const { actor, tenant } = await this.gate(slug, jwt)
+    const updated = await this.users.updateTenantMember(
+      { _id: tenant._id, slug: tenant.slug },
+      userId,
+      dto,
+      auditActor(actor, req),
+    )
+    return { ...updated.toObject(), tenantRole: roleForTenant(updated, tenant._id) }
+  }
+
+  // Change a mailbox-less member's primary email (Authentik identity only).
+  @Patch(':userId/primary-email')
+  async changePrimaryEmail(
+    @Param('slug') slug: string,
+    @Param('userId') userId: string,
+    @Body() dto: ChangePrimaryEmailDto,
+    @CurrentUser() jwt: AuthentikJwtPayload,
+    @Req() req: Parameters<typeof clientIp>[0],
+  ) {
+    const { actor, tenant } = await this.gate(slug, jwt)
+    const updated = await this.users.changeMemberPrimaryEmail(
+      { _id: tenant._id, slug: tenant.slug },
+      userId,
+      dto.email,
+      auditActor(actor, req),
+    )
+    return { ...updated.toObject(), tenantRole: roleForTenant(updated, tenant._id) }
+  }
+
+  // Transfer workspace ownership to this member. Gated to tenant admins / the
+  // current owner / platform admins — NOT only the owner, since the common case
+  // is the owner having left. Demotes the previous owner to admin.
+  @Post(':userId/make-owner')
+  async makeOwner(
+    @Param('slug') slug: string,
+    @Param('userId') userId: string,
+    @CurrentUser() jwt: AuthentikJwtPayload,
+    @Req() req: Parameters<typeof clientIp>[0],
+  ) {
+    const { actor, tenant } = await this.gate(slug, jwt)
+    const actorRole = roleForTenant(actor, tenant._id)
+    if (!actor.platformAdmin && actorRole !== 'admin' && actorRole !== 'owner') {
+      throw new ForbiddenException('Only an admin or the owner can transfer ownership.')
+    }
+    const res = await this.users.transferOwnership(
+      { _id: tenant._id, slug: tenant.slug },
+      userId,
+      auditActor(actor, req),
+    )
+    return {
+      newOwner: { ...res.newOwner.toObject(), tenantRole: roleForTenant(res.newOwner, tenant._id) },
+      previousOwners: res.previousOwners.map((u) => ({
+        ...u.toObject(),
+        tenantRole: roleForTenant(u, tenant._id),
+      })),
+    }
+  }
+
+  // Provision a mailbox for a member who has none (e.g. the bootstrap admin who
+  // signs in with an external email). Returns the new address + a one-time
+  // password, plus the refreshed user doc so the UI can flip the panel.
+  @Post(':userId/mailbox')
+  async createMailbox(
+    @Param('slug') slug: string,
+    @Param('userId') userId: string,
+    @Body() dto: CreateMailboxDto,
+    @CurrentUser() jwt: AuthentikJwtPayload,
+    @Req() req: Parameters<typeof clientIp>[0],
+  ) {
+    const { actor, tenant } = await this.gate(slug, jwt)
+    const res = await this.users.createMailboxForMember(
+      { _id: tenant._id, slug: tenant.slug },
+      userId,
+      dto,
+      auditActor(actor, req),
+    )
+    return {
+      email: res.email,
+      tempPassword: res.tempPassword,
+      user: { ...res.user.toObject(), tenantRole: roleForTenant(res.user, tenant._id) },
+    }
+  }
+
+  // Mailbox aliases (extra addresses that deliver to the member's inbox).
+  @Get(':userId/aliases')
+  async listAliases(
+    @Param('slug') slug: string,
+    @Param('userId') userId: string,
+    @CurrentUser() jwt: AuthentikJwtPayload,
+  ) {
+    const { tenant } = await this.gate(slug, jwt)
+    return this.users.listMemberAliases({ _id: tenant._id, slug: tenant.slug }, userId)
+  }
+
+  @Post(':userId/aliases')
+  async addAlias(
+    @Param('slug') slug: string,
+    @Param('userId') userId: string,
+    @Body() dto: AddAliasDto,
+    @CurrentUser() jwt: AuthentikJwtPayload,
+    @Req() req: Parameters<typeof clientIp>[0],
+  ) {
+    const { actor, tenant } = await this.gate(slug, jwt)
+    return this.users.addMemberAlias(
+      { _id: tenant._id, slug: tenant.slug },
+      userId,
+      dto,
+      auditActor(actor, req),
+    )
+  }
+
+  @Delete(':userId/aliases')
+  async removeAlias(
+    @Param('slug') slug: string,
+    @Param('userId') userId: string,
+    @Body() dto: RemoveAliasDto,
+    @CurrentUser() jwt: AuthentikJwtPayload,
+    @Req() req: Parameters<typeof clientIp>[0],
+  ) {
+    const { actor, tenant } = await this.gate(slug, jwt)
+    return this.users.removeMemberAlias(
+      { _id: tenant._id, slug: tenant.slug },
+      userId,
+      dto.address,
+      auditActor(actor, req),
+    )
+  }
 }

services/platform-api/src/users/users.service.ts

@@ -19,7 +19,7 @@ import { Partner, PartnerDocument } from '../schemas/partner.schema.js'
 import { Price, PriceDocument } from '../schemas/price.schema.js'
 import { Subscription, SubscriptionDocument } from '../schemas/subscription.schema.js'
 import { Tenant, TenantDocument } from '../schemas/tenant.schema.js'
-import { User, UserDocument } from '../schemas/user.schema.js'
+import { User, UserDocument, roleForTenant } from '../schemas/user.schema.js'
 import type { CreateUserDto } from './dto/create-user.dto.js'
 import type { InviteOperatorDto } from './dto/invite-operator.dto.js'
 import type { InvitePartnerUserDto } from './dto/invite-partner-user.dto.js'
@@ -974,6 +974,418 @@ export class UsersService {
     return { email: user.email, tempPassword }
   }
 
+  // Update a member's directory profile (display name + contact info) and/or
+  // their in-tenant role. Contact info is mirrored to Authentik attributes and
+  // the mailbox display name on a best-effort basis — the DB is authoritative,
+  // so an unreachable Authentik/Stalwart never blocks the local save. Returns
+  // the updated doc so the caller can echo the fresh state back to the UI.
+  async updateTenantMember(
+    tenant: { _id: Types.ObjectId; slug: string },
+    userId: string,
+    dto: {
+      name?: string
+      firstName?: string
+      lastName?: string
+      phone?: string
+      alternativeEmail?: string
+      role?: 'admin' | 'member'
+    },
+    actor?: AuditActor,
+  ): Promise<UserDocument> {
+    const { user } = await this.loadMember(tenant, userId)
+
+    // Role change (in-tenant). The workspace's primary account — its owner and
+    // the mailbox-less bootstrap admin (invited on a private email to set the
+    // workspace up) — has an immutable role; so does the actor's own account
+    // (no self-demotion). Contact-info edits on these accounts are still
+    // allowed — only the role is frozen. We also never strip the last
+    // admin/owner so a workspace can't lock itself out.
+    if (dto.role !== undefined) {
+      const current = roleForTenant(user, tenant._id)
+      const isPrimary = current === 'owner' || (!user.stalwartAccountId && !user.mailboxAddress)
+      if (isPrimary) {
+        throw new ForbiddenException('The primary account’s role can’t be changed.')
+      }
+      if (actor?.userId && actor.userId === String(user._id)) {
+        throw new ForbiddenException('You can’t change your own role.')
+      }
+      if (dto.role === 'member' && current === 'admin') {
+        const tenantUsers = await this.userModel.find({ tenantIds: tenant._id }).exec()
+        const otherAdmins = tenantUsers.filter(
+          (u) =>
+            !u._id.equals(user._id) &&
+            ['admin', 'owner'].includes(roleForTenant(u, tenant._id)),
+        )
+        if (otherAdmins.length === 0) {
+          throw new ConflictException('Can’t remove the last admin of this workspace.')
+        }
+      }
+    }
+
+    const set: Record<string, unknown> = {}
+    if (dto.name !== undefined) set.name = dto.name
+    if (dto.firstName !== undefined) set.firstName = dto.firstName
+    if (dto.lastName !== undefined) set.lastName = dto.lastName
+    if (dto.phone !== undefined) set.phone = dto.phone
+    if (dto.alternativeEmail !== undefined) set.alternativeEmail = dto.alternativeEmail
+    if (dto.role !== undefined) set[`tenantRoles.${tenant._id}`] = dto.role
+
+    if (Object.keys(set).length === 0) return user
+
+    const updated = await this.userModel
+      .findOneAndUpdate({ _id: user._id }, { $set: set }, { new: true, runValidators: true })
+      .exec()
+    if (!updated) throw new NotFoundException('User not found')
+
+    // Best-effort Authentik sync: display name + contact attributes.
+    const attrs: Record<string, unknown> = {}
+    if (dto.firstName !== undefined) attrs.firstName = dto.firstName
+    if (dto.lastName !== undefined) attrs.lastName = dto.lastName
+    if (dto.phone !== undefined) attrs.phone = dto.phone
+    if (dto.alternativeEmail !== undefined) attrs.alternativeEmail = dto.alternativeEmail
+    if (user.authentikUserPk && (dto.name !== undefined || Object.keys(attrs).length > 0)) {
+      await this.authentik
+        .updateUser(user.authentikUserPk, {
+          name: dto.name,
+          attributesMerge: Object.keys(attrs).length > 0 ? attrs : undefined,
+        })
+        .catch((err) =>
+          this.logger.warn(
+            `Authentik profile sync failed for ${user.email}: ${(err as Error).message}`,
+          ),
+        )
+    }
+
+    // Best-effort mailbox display-name sync.
+    if (dto.name !== undefined && this.stalwart.configured && user.stalwartAccountId) {
+      await this.stalwart
+        .setMailboxName(user.stalwartAccountId, dto.name)
+        .catch((err) =>
+          this.logger.warn(
+            `Mailbox name sync failed for ${user.email}: ${(err as Error).message}`,
+          ),
+        )
+    }
+
+    void this.audit.record(
+      {
+        action: 'tenant.user_updated',
+        resourceType: 'user',
+        resourceId: updated.authentikSubjectId,
+        resourceName: updated.email,
+        tenantSlug: tenant.slug,
+        metadata: {
+          fields: Object.keys(set),
+          ...(dto.role !== undefined ? { role: dto.role } : {}),
+        },
+      },
+      actor,
+    )
+
+    return updated
+  }
+
+  // Change a mailbox-less member's primary email — their Authentik sign-in
+  // username + email, kept aligned, plus our User.email. This is ONLY for
+  // identities with no Stalwart mailbox (e.g. the bootstrap admin invited on a
+  // private email): for a real mailbox, the primary address IS the inbox, so
+  // moving it would split sign-in from delivery and we refuse. Authentik's
+  // stable `uid` (our authentikSubjectId) is unaffected by an email change, so
+  // the user's identity survives the rename.
+  async changeMemberPrimaryEmail(
+    tenant: { _id: Types.ObjectId; slug: string },
+    userId: string,
+    newEmailRaw: string,
+    actor?: AuditActor,
+  ): Promise<UserDocument> {
+    const { user } = await this.loadMember(tenant, userId)
+
+    if (user.stalwartAccountId || user.mailboxAddress) {
+      throw new BadRequestException(
+        'This member has a mailbox — their primary address is their inbox and can’t be changed here. Add an alias instead.',
+      )
+    }
+    if (!user.authentikUserPk) {
+      throw new BadRequestException('This member isn’t linked to an identity yet.')
+    }
+
+    const newEmail = newEmailRaw.trim().toLowerCase()
+    if (!/^[^\s@]+@[^\s@]+\.[^\s@]+$/.test(newEmail)) {
+      throw new BadRequestException('Enter a valid email address.')
+    }
+    if (newEmail === user.email.toLowerCase()) return user
+
+    // Not already taken — in Authentik or our own collection.
+    const existingAk = await this.authentik.findUserByEmail(newEmail)
+    if (existingAk && existingAk.uid !== user.authentikSubjectId) {
+      throw new ConflictException(`${newEmail} is already in use.`)
+    }
+    const existingLocal = await this.userModel
+      .findOne({ email: newEmail, _id: { $ne: user._id } })
+      .exec()
+    if (existingLocal) throw new ConflictException(`${newEmail} is already in use.`)
+
+    // Identity source first — if Authentik rejects, abort before our record so
+    // the two never diverge.
+    await this.authentik.updateUser(user.authentikUserPk, { username: newEmail, email: newEmail })
+
+    const prevEmail = user.email
+    user.email = newEmail
+    await user.save()
+
+    void this.audit.record(
+      {
+        action: 'tenant.user_primary_email_changed',
+        resourceType: 'user',
+        resourceId: user.authentikSubjectId,
+        resourceName: newEmail,
+        tenantSlug: tenant.slug,
+        metadata: { from: prevEmail, to: newEmail },
+      },
+      actor,
+    )
+
+    return user
+  }
+
+  // List a member's mailbox aliases as full addresses. Aliases live in Stalwart
+  // as {name, domainId}; we resolve domainId → domain name via this tenant's
+  // domains so the UI gets `info@acme.dk`, not an opaque id. Members without a
+  // mailbox (SSO-only) come back with hasMailbox=false and no aliases.
+  async listMemberAliases(
+    tenant: { _id: Types.ObjectId; slug: string },
+    userId: string,
+  ): Promise<{ hasMailbox: boolean; primary: string; aliases: string[] }> {
+    const { user } = await this.loadMember(tenant, userId)
+    const primary = user.mailboxAddress ?? user.email
+    if (!this.stalwart.configured || !user.stalwartAccountId) {
+      return { hasMailbox: false, primary, aliases: [] }
+    }
+    const [accounts, domains] = await Promise.all([
+      this.stalwart.listAccountsWithAliases(),
+      this.domainModel.find({ tenantId: tenant._id }, { domain: 1, stalwartId: 1 }).exec(),
+    ])
+    const acct = accounts.find((a) => a.id === user.stalwartAccountId)
+    if (!acct) return { hasMailbox: true, primary, aliases: [] }
+    const domainById = new Map(
+      domains.filter((d) => d.stalwartId).map((d) => [d.stalwartId as string, d.domain]),
+    )
+    const aliases = acct.aliases
+      .map((a) => {
+        const dom = domainById.get(a.domainId)
+        return dom ? `${a.name}@${dom}` : null
+      })
+      .filter((x): x is string => x !== null)
+    return { hasMailbox: true, primary: acct.emailAddress || primary, aliases }
+  }
+
+  // Add an alias to a member's mailbox. The alias domain must be one of this
+  // tenant's provisioned mail domains, and the address must be free. Returns
+  // the refreshed alias view.
+  async addMemberAlias(
+    tenant: { _id: Types.ObjectId; slug: string },
+    userId: string,
+    dto: { localPart: string; domain: string },
+    actor?: AuditActor,
+  ): Promise<{ hasMailbox: boolean; primary: string; aliases: string[] }> {
+    const { user } = await this.loadMember(tenant, userId)
+    if (!this.stalwart.configured || !user.stalwartAccountId) {
+      throw new BadRequestException('This member has no mailbox to attach an alias to.')
+    }
+    const localPart = dto.localPart.trim().toLowerCase()
+    if (!/^[a-z0-9._-]+$/.test(localPart)) {
+      throw new BadRequestException(
+        'The alias prefix may only contain letters, numbers, dots, hyphens and underscores.',
+      )
+    }
+    const domain = dto.domain.trim().toLowerCase()
+    const domainDoc = await this.domainModel.findOne({ tenantId: tenant._id, domain }).exec()
+    if (!domainDoc?.stalwartId) {
+      throw new BadRequestException(`${domain} isn’t a provisioned mail domain for this workspace.`)
+    }
+    const address = `${localPart}@${domain}`
+    const taken = await this.stalwart.findAccountIdByEmail(address)
+    if (taken) throw new ConflictException(`${address} is already in use.`)
+
+    await this.stalwart.addAlias(user.stalwartAccountId, localPart, domainDoc.stalwartId)
+    void this.audit.record(
+      {
+        action: 'tenant.user_alias_added',
+        resourceType: 'user',
+        resourceId: user.authentikSubjectId,
+        resourceName: user.email,
+        tenantSlug: tenant.slug,
+        metadata: { alias: address },
+      },
+      actor,
+    )
+    return this.listMemberAliases(tenant, userId)
+  }
+
+  // Remove an alias (by full address) from a member's mailbox.
+  async removeMemberAlias(
+    tenant: { _id: Types.ObjectId; slug: string },
+    userId: string,
+    addressRaw: string,
+    actor?: AuditActor,
+  ): Promise<{ hasMailbox: boolean; primary: string; aliases: string[] }> {
+    const { user } = await this.loadMember(tenant, userId)
+    if (!this.stalwart.configured || !user.stalwartAccountId) {
+      throw new BadRequestException('This member has no mailbox.')
+    }
+    const [localPart, domain] = addressRaw.trim().toLowerCase().split('@')
+    if (!localPart || !domain) throw new BadRequestException('Invalid alias address.')
+    const domainDoc = await this.domainModel.findOne({ tenantId: tenant._id, domain }).exec()
+    if (!domainDoc?.stalwartId) {
+      throw new BadRequestException(`${domain} isn’t a mail domain for this workspace.`)
+    }
+    await this.stalwart.removeAlias(user.stalwartAccountId, localPart, domainDoc.stalwartId)
+    void this.audit.record(
+      {
+        action: 'tenant.user_alias_removed',
+        resourceType: 'user',
+        resourceId: user.authentikSubjectId,
+        resourceName: user.email,
+        tenantSlug: tenant.slug,
+        metadata: { alias: `${localPart}@${domain}` },
+      },
+      actor,
+    )
+    return this.listMemberAliases(tenant, userId)
+  }
+
+  // Provision a Stalwart mailbox for a member who doesn't have one yet — the
+  // bootstrap admin who signs in with an external email, typically. Their
+  // sign-in identity (Authentik username/email + User.email) is left untouched;
+  // we only attach a mailbox on a tenant domain and store its handles, so they
+  // can use webmail/IMAP and (the point of it) receive aliases. A fresh temp
+  // password is set on the mailbox and returned once for hand-off.
+  async createMailboxForMember(
+    tenant: { _id: Types.ObjectId; slug: string },
+    userId: string,
+    dto: { localPart: string; domain?: string },
+    actor?: AuditActor,
+  ): Promise<{ email: string; tempPassword: string; user: UserDocument }> {
+    const { user } = await this.loadMember(tenant, userId)
+    if (user.stalwartAccountId || user.mailboxAddress) {
+      throw new ConflictException('This member already has a mailbox.')
+    }
+    if (!this.stalwart.configured) {
+      throw new BadRequestException('Mail provisioning is disabled — can’t create a mailbox right now.')
+    }
+
+    // Resolve the target domain — named, else primary, else oldest (mirrors
+    // createTenantMember).
+    let domainDoc: DomainDocument | null
+    if (dto.domain) {
+      domainDoc = await this.domainModel
+        .findOne({ tenantId: tenant._id, domain: dto.domain.toLowerCase() })
+        .exec()
+    } else {
+      domainDoc = await this.domainModel.findOne({ tenantId: tenant._id, isPrimary: true }).exec()
+      if (!domainDoc) {
+        domainDoc = await this.domainModel
+          .findOne({ tenantId: tenant._id })
+          .sort({ createdAt: 1 })
+          .exec()
+      }
+    }
+    if (!domainDoc) {
+      throw new BadRequestException('Add a domain to this workspace before creating a mailbox.')
+    }
+    if (!domainDoc.stalwartId) {
+      throw new BadRequestException(`${domainDoc.domain} isn’t a provisioned mail domain for this workspace.`)
+    }
+
+    const localPart = dto.localPart.trim().toLowerCase()
+    if (!/^[a-z0-9._-]+$/.test(localPart)) {
+      throw new BadRequestException(
+        'The address prefix may only contain letters, numbers, dots, hyphens and underscores.',
+      )
+    }
+    const email = `${localPart}@${domainDoc.domain}`
+    const taken = await this.stalwart.findAccountIdByEmail(email)
+    if (taken) throw new ConflictException(`${email} is already in use.`)
+
+    const tempPassword = generateTempPassword()
+    const mbx = await this.stalwart.createMailbox({
+      domainId: domainDoc.stalwartId,
+      localPart,
+      fullName: user.name,
+      password: tempPassword,
+    })
+
+    user.mailboxAddress = email
+    user.stalwartAccountId = mbx.id
+    user.provisioning = { ...(user.provisioning ?? {}), stalwart: 'ok' }
+    await user.save()
+
+    void this.audit.record(
+      {
+        action: 'tenant.user_mailbox_created',
+        resourceType: 'user',
+        resourceId: user.authentikSubjectId,
+        resourceName: email,
+        tenantSlug: tenant.slug,
+        metadata: { mailbox: email, signIn: user.email },
+      },
+      actor,
+    )
+
+    return { email, tempPassword, user }
+  }
+
+  // Transfer workspace ownership to another member. The named member becomes
+  // 'owner' for this tenant; any existing owner is demoted to 'admin' (never
+  // removed — they keep access until an admin decides otherwise). Built for the
+  // "owner left the company" case, so the actor doesn't have to BE the owner —
+  // the controller gates it to tenant admins / platform admins. Only the
+  // per-tenant role moves; the legacy global `role` and every other tenant's
+  // role are untouched.
+  async transferOwnership(
+    tenant: { _id: Types.ObjectId; slug: string },
+    newOwnerUserId: string,
+    actor?: AuditActor,
+  ): Promise<{ newOwner: UserDocument; previousOwners: UserDocument[] }> {
+    const { user: newOwner } = await this.loadMember(tenant, newOwnerUserId)
+    if (roleForTenant(newOwner, tenant._id) === 'owner') {
+      throw new ConflictException('This member is already the owner.')
+    }
+
+    const tenantUsers = await this.userModel.find({ tenantIds: tenant._id }).exec()
+    const previousOwners = tenantUsers.filter(
+      (u) => roleForTenant(u, tenant._id) === 'owner' && !u._id.equals(newOwner._id),
+    )
+
+    await this.userModel
+      .updateOne({ _id: newOwner._id }, { $set: { [`tenantRoles.${tenant._id}`]: 'owner' } })
+      .exec()
+    for (const prev of previousOwners) {
+      await this.userModel
+        .updateOne({ _id: prev._id }, { $set: { [`tenantRoles.${tenant._id}`]: 'admin' } })
+        .exec()
+    }
+
+    void this.audit.record(
+      {
+        action: 'tenant.ownership_transferred',
+        resourceType: 'user',
+        resourceId: newOwner.authentikSubjectId,
+        resourceName: newOwner.email,
+        tenantSlug: tenant.slug,
+        metadata: { to: newOwner.email, from: previousOwners.map((p) => p.email) },
+      },
+      actor,
+    )
+
+    // Return fresh docs so the caller's roleForTenant() reflects the new state.
+    const freshNewOwner = await this.userModel.findById(newOwner._id).exec()
+    const freshPrev = previousOwners.length
+      ? await this.userModel.find({ _id: { $in: previousOwners.map((p) => p._id) } }).exec()
+      : []
+    return { newOwner: freshNewOwner ?? newOwner, previousOwners: freshPrev }
+  }
+
   async inviteTenantAdmin(
     tenant: { _id: Types.ObjectId; slug: string; authentikGroupId?: string },
     dto: { name: string; email: string },