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, 6 deletions

diff --git a/packages/meshbay-hub/tests/test_group_leave_and_quota.py b/packages/meshbay-hub/tests/test_group_leave_and_quota.py
index 8af830d..e4efc09 100644
--- a/packages/meshbay-hub/tests/test_group_leave_and_quota.py
+++ b/packages/meshbay-hub/tests/test_group_leave_and_quota.py
@@ -17,6 +17,7 @@ import hashlib
 from datetime import UTC, datetime
 
 import pytest
+from membership import add_member
 from meshbay_hub.api.groups import MAX_PUBLIC_GROUPS
 from meshbay_hub.db.models import Group, GroupMember, User
 from sqlalchemy import select
@@ -55,7 +56,7 @@ async def test_a_member_can_leave(client, db_session):
     owner = await _user(client, "owner1_test")
     member = await _user(client, "member1_test")
     gid = await _group(client, owner, "readers")
-    await client.post(f"/v1/groups/{gid}/members/member1_test", json={}, headers=owner)
+    await add_member(client, gid, 'member1_test', owner)
 
     # Marked hosted, or the member would not see the group in the first place
     # and the assertion below would hold whether or not leaving worked.
@@ -80,7 +81,7 @@ async def test_leaving_removes_only_that_membership_row(client, db_session):
     owner = await _user(client, "owner2_test")
     member = await _user(client, "member2_test")
     gid = await _group(client, owner, "still-here")
-    await client.post(f"/v1/groups/{gid}/members/member2_test", json={}, headers=owner)
+    await add_member(client, gid, 'member2_test', owner)
 
     await client.post(f"/v1/groups/{gid}/leave", headers=member)
 
@@ -100,8 +101,8 @@ async def test_leaving_does_not_touch_the_account_or_its_other_groups(client, db
     elsewhere = await _user(client, "owner3b_test")
     gid = await _group(client, owner, "leaving")
     other = await _group(client, elsewhere, "staying")
-    await client.post(f"/v1/groups/{gid}/members/member3_test", json={}, headers=owner)
-    await client.post(f"/v1/groups/{other}/members/member3_test", json={}, headers=elsewhere)
+    await add_member(client, gid, 'member3_test', owner)
+    await add_member(client, other, 'member3_test', elsewhere)
 
     await client.post(f"/v1/groups/{gid}/leave", headers=member)
 
@@ -130,7 +131,7 @@ async def test_leaving_twice_is_refused(client):
     owner = await _user(client, "owner5_test")
     member = await _user(client, "member5_test")
     gid = await _group(client, owner, "once")
-    await client.post(f"/v1/groups/{gid}/members/member5_test", json={}, headers=owner)
+    await add_member(client, gid, 'member5_test', owner)
 
     assert (await client.post(f"/v1/groups/{gid}/leave",
                               headers=member)).status_code == 200
@@ -203,7 +204,7 @@ async def test_the_cap_is_per_owner(client):
     b = await _user(client, "ownerb2_test")
     for i in range(MAX_PUBLIC_GROUPS):
         gid = await _group(client, a, f"a-pub-{i}", visibility="public")
-        await client.post(f"/v1/groups/{gid}/members/ownerb2_test", json={}, headers=a)
+        await add_member(client, gid, 'ownerb2_test', a)
 
     r = await client.post("/v1/groups",
                           json={"name": "b-first", "visibility": "public",