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, 39 insertions, 0 deletions

diff --git a/packages/meshbay-hub/tests/membership.py b/packages/meshbay-hub/tests/membership.py
new file mode 100644
index 0000000..041eb74
--- /dev/null
+++ b/packages/meshbay-hub/tests/membership.py
@@ -0,0 +1,39 @@
+"""
+Making somebody a member, the way the product does it.
+
+An owner adding a username creates an *invitation*; the account becomes a
+member only when it accepts (`POST /v1/groups/{id}/invitation/accept`). Tests
+that need a member go through both steps, with a token of the invitee's own —
+a shortcut that wrote `GroupMember` directly would test a hub where adding
+someone still made them a member without asking, which is the hole this
+closed.
+"""
+
+from meshbay_hub.auth import issue_access_token
+from meshbay_hub.db.engine import get_session_factory
+from meshbay_hub.db.models import User
+from sqlalchemy import select
+
+
+async def token_of(username: str) -> str:
+    async with get_session_factory()() as db:
+        uid = await db.scalar(select(User.id).where(User.username == username))
+    assert uid, f"no such account {username!r}"
+    return issue_access_token(uid)
+
+
+async def accept_invitation(client, group_id: str, username: str) -> None:
+    tok = await token_of(username)
+    r = await client.post(f"/v1/groups/{group_id}/invitation/accept",
+                          headers={"Authorization": f"Bearer {tok}"})
+    assert r.status_code == 200, r.text
+
+
+async def add_member(client, group_id: str, username: str, owner_headers: dict):
+    """Invite, then accept as the invitee. Returns the invitation response."""
+    r = await client.post(f"/v1/groups/{group_id}/members/{username}", json={},
+                          headers=owner_headers)
+    assert r.status_code in (200, 201), r.text
+    if r.json().get("status") == "invited":
+        await accept_invitation(client, group_id, username)
+    return r