fix: only the owner decides who hosts a group, and nobody is made a member unasked

- hub: a node may host a group only if its account owns it or the owner
  approved that node (new `group_hosts`). Membership was the ceiling, and
  every member holds the group key, so any member's node could register as a
  host and be the one clients kept. A node claiming a group it may not host
  is recorded as a request; the owner is notified once and approves or
  refuses it (GET/POST/DELETE /v1/groups/{id}/hosts[/{node_id}]), which
  takes effect on a connected node at once.
- hub: an owner adding a username creates an invitation (new
  `group_invitations`), accepted or declined by the invitee
  (/v1/groups/invitations, /{id}/invitation/accept|decline). Until then the
  group is not listed, not dialled, not searched and not in any token.
  Invitation links, open joins and group creation still make members
  directly: they are the account's own act.
- hub: the MNP token names only the group it is minted for (group_id is now
  required), so a node operator no longer learns a member's other groups.
- SPA: invitations on the home page; invited people and host requests in
  the group's settings; the transport sends group_id. Ten catalogues.
- Browser probes for both screens, run in Chrome and Firefox.
- Design §5.2, §7.2, §7.3, AV32, AV33; protocol §6.3; user guide.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

1 files changed, 7 insertions, 0 deletions

diff --git a/packages/meshbay-hub/src/meshbay_hub/api/users.py b/packages/meshbay-hub/src/meshbay_hub/api/users.py
index 3e996a7..660bd76 100644
--- a/packages/meshbay-hub/src/meshbay_hub/api/users.py
+++ b/packages/meshbay-hub/src/meshbay_hub/api/users.py
@@ -35,6 +35,8 @@ from meshbay_hub.db.engine import get_db
 from meshbay_hub.db.models import (
     EmailVerification,
     Group,
+    GroupHost,
+    GroupInvitation,
     GroupInviteLink,
     GroupMember,
     IPLog,
@@ -1415,6 +1417,11 @@ async def erase_account(db: AsyncSession, user: User, owned_groups: str = "refus
     await db.execute(delete(GroupMember).where(GroupMember.user_id == user.id))
     await db.execute(delete(Notification).where(Notification.user_id == user.id))
     await db.execute(delete(RefreshToken).where(RefreshToken.user_id == user.id))
+    await db.execute(delete(GroupInvitation).where(GroupInvitation.user_id == user.id))
+    await db.execute(update(GroupInvitation).where(GroupInvitation.invited_by == user.id)
+                     .values(invited_by=None))
+    await db.execute(delete(GroupHost).where(
+        GroupHost.node_id.in_(select(Node.id).where(Node.user_id == user.id))))
     await db.execute(delete(Node).where(Node.user_id == user.id))
     await db.execute(delete(UserDevice).where(UserDevice.user_id == user.id))
     await db.execute(delete(EmailVerification).where(EmailVerification.user_id == user.id))