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, 6 insertions, 11 deletions

diff --git a/packages/meshbay-hub/tests/test_hub_api.py b/packages/meshbay-hub/tests/test_hub_api.py
index 162b074..378bbb8 100644
--- a/packages/meshbay-hub/tests/test_hub_api.py
+++ b/packages/meshbay-hub/tests/test_hub_api.py
@@ -3,13 +3,14 @@ Integration tests for the Hub API.
 Uses SQLite in-memory + httpx.AsyncClient — no PostgreSQL, no network.
 """
 
-from meshbay_common.tokens import HUB_API_AUD
 from datetime import UTC
 
 import pytest
 from cryptography.hazmat.primitives.asymmetric.ed25519 import Ed25519PrivateKey
 from cryptography.hazmat.primitives.asymmetric.x25519 import X25519PrivateKey
+from membership import add_member
 from meshbay_common.crypto import pk_to_b64
+from meshbay_common.tokens import HUB_API_AUD
 from meshbay_hub.api.deps import set_admin_usernames
 
 
@@ -272,8 +273,7 @@ async def test_group_member_add(client):
     group_id = r.json()["group_id"]
 
     # Add bob as member (hub handles membership only, GEK exchange is P2P)
-    r = await client.post(f"/v1/groups/{group_id}/members/bob2_test",
-                          json={}, headers=a_hdrs)
+    r = await add_member(client, group_id, 'bob2_test', a_hdrs)
     assert r.status_code == 201
 
     # Verify bob is in the group
@@ -314,8 +314,7 @@ async def test_non_admin_cannot_add_member(client):
     group_id = r.json()["group_id"]
 
     # Dan (non-admin) tries to add a member → 403
-    r = await client.post(f"/v1/groups/{group_id}/members/charlie_test",
-                          json={},
+    r = await client.post(f"/v1/groups/{group_id}/members/charlie_test", json={},
                           headers={"Authorization": f"Bearer {dan_token}"})
     assert r.status_code == 403
 
@@ -352,9 +351,7 @@ async def test_jwt_contains_groups_claim(client):
                           headers={"Authorization": f"Bearer {alice_token}"})
     group_id = r.json()["group_id"]
 
-    await client.post(f"/v1/groups/{group_id}/members/grp_bob_test",
-                      json={},
-                      headers={"Authorization": f"Bearer {alice_token}"})
+    await add_member(client, group_id, 'grp_bob_test', {"Authorization": f"Bearer {alice_token}"})
 
     # Login again — groups should contain the new group
     r = await client.post("/v1/users/login", json={
@@ -400,9 +397,7 @@ async def test_my_groups(client, db_session):
     r = await client.post("/v1/groups", json={"name": "mg-group"},
                           headers={"Authorization": f"Bearer {alice_token}"})
     group_id = r.json()["group_id"]
-    await client.post(f"/v1/groups/{group_id}/members/mg_bob_test",
-                      json={},
-                      headers={"Authorization": f"Bearer {alice_token}"})
+    await add_member(client, group_id, 'mg_bob_test', {"Authorization": f"Bearer {alice_token}"})
 
     # A group no node has announced is shown to its owner only — a member would
     # otherwise see a name they cannot open. Stamped here so the rest of this