feat(hub): group names unique per owner, shown as name@owner

A group's identity stays its UUID. What changes is that "the name is
unique" — until now an unenforced expectation — becomes real, scoped to the
owner account, and the owner's username is surfaced so two groups called
"photos" on different nodes can be told apart.

Hub:
- `groups` gains a functional unique index `uq_groups_owner_name` on
  `(admin_id, lower(name))` (model + migration c3d4e5f6a7b8). The migration
  pre-flights: if the data already clashes it aborts and lists the
  offending (admin_id, name) pairs rather than renaming anyone's group.
  meshbay.org checked clean.
- `create_group` trims the name, rejects blank (422) and an owner-scoped
  case-insensitive clash (409), with an IntegrityError backstop for the
  race, and returns `owner_username`.
- `owner_username` added to `/v1/groups/mine`, `GET /v1/groups` (local
  rows), `POST /v1/groups/{id}/join`, `GET /v1/admin/groups`.

SPA:
- new `static/group-name.js` — `<GroupName name owner [inline]>` renders the
  name with the `@owner` handle on a smaller grey line under it.
- used in the sidebar, the group-page header, Explore cards, the Admin
  groups table, and cross-group Search (via a widened `cacheGroupIndex`
  carrying the owner). Delete/leave confirmations show `name@owner` inline.
- federated Explore rows show `@<source_hub>` instead of an account.

Design record and the locked decisions: ~/next/groupnames.md (out of repo).
MNP unchanged. Tests: test_group_name_unique.py, test_group_name_migration.py.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_018gKJ85aZyvEwarXMFzFEwi

1 files changed, 78 insertions, 0 deletions

diff --git a/packages/meshbay-hub/tests/test_group_name_unique.py b/packages/meshbay-hub/tests/test_group_name_unique.py
new file mode 100644
index 0000000..2bc109c
--- /dev/null
+++ b/packages/meshbay-hub/tests/test_group_name_unique.py
@@ -0,0 +1,78 @@
+"""
+A group name is unique per owner account, case-insensitively — the group's
+identity stays its UUID, this only makes `name@owner` a dependable handle.
+"""
+
+import base64
+import hashlib
+
+import pytest
+
+
+def _auth_key(password: str, username: str) -> str:
+    salt = hashlib.sha256(f"meshbay:auth:v1:{username}".encode()).digest()
+    return base64.b64encode(
+        hashlib.pbkdf2_hmac("sha512", password.encode(), salt, 600_000, 32)).decode()
+
+
+async def _user(client, username, password="a-long-enough-passphrase"):
+    await client.post("/v1/users/register", json={
+        "username": username, "email": f"{username}@example.com",
+        "auth_key": _auth_key(password, username)})
+    r = await client.post("/v1/users/login", json={
+        "username": username, "auth_key": _auth_key(password, username)})
+    return {"Authorization": f"Bearer {r.json()['access_token']}"}
+
+
+async def _create(client, headers, name):
+    return await client.post("/v1/groups", json={"name": name}, headers=headers)
+
+
+@pytest.mark.asyncio
+async def test_same_owner_same_name_is_refused(client):
+    alice = await _user(client, "alice")
+    r1 = await _create(client, alice, "photos")
+    assert r1.status_code == 201
+    assert r1.json()["owner_username"] == "alice"
+
+    r2 = await _create(client, alice, "photos")
+    assert r2.status_code == 409
+    assert "photos" in r2.json()["detail"]
+
+
+@pytest.mark.asyncio
+async def test_same_owner_different_case_is_refused(client):
+    alice = await _user(client, "alice")
+    assert (await _create(client, alice, "Photos")).status_code == 201
+    assert (await _create(client, alice, "  photos ")).status_code == 409
+
+
+@pytest.mark.asyncio
+async def test_two_owners_may_share_a_name(client):
+    alice = await _user(client, "alice")
+    bob = await _user(client, "bob")
+    assert (await _create(client, alice, "photos")).status_code == 201
+    assert (await _create(client, bob, "photos")).status_code == 201
+
+
+@pytest.mark.asyncio
+async def test_name_is_trimmed_on_create(client):
+    alice = await _user(client, "alice")
+    r = await _create(client, alice, "  spaced out  ")
+    assert r.status_code == 201
+    assert r.json()["name"] == "spaced out"
+
+
+@pytest.mark.asyncio
+async def test_blank_name_is_refused(client):
+    alice = await _user(client, "alice")
+    assert (await _create(client, alice, "   ")).status_code == 422
+
+
+@pytest.mark.asyncio
+async def test_owner_username_is_reported_in_listings(client):
+    alice = await _user(client, "alice")
+    await _create(client, alice, "photos")
+
+    mine = (await client.get("/v1/groups/mine", headers=alice)).json()["groups"]
+    assert mine and mine[0]["owner_username"] == "alice"