style: ruff's own fixes, mechanically applied

2026-09-19T12:24:13Z

`ruff check .` had gone unrun long enough to report 568 errors, which is the same as having no linter: the next real finding would have been invisible in the noise. This is the 521 it fixes by itself, in 173 files, and nothing else — the 98 it cannot fix are the next commit. What actually changed: import sorting (225), imports nobody used (87, none of them a re-export — no `__init__.py` is touched, which was the one way this could have broken an import elsewhere), `datetime.timezone.utc` to `datetime.UTC` (69) and `asyncio.TimeoutError` to `TimeoutError` (18), both plain aliases on the 3.12 this project requires, `Optional[X]` to `X | None` (24), and f-strings with nothing to interpolate (19). Checked rather than assumed: every module in the three packages still imports, and the suite is 2893 passed — the same count, test for test, as the merge before it. Co-Authored-By: Claude Opus 5

fix: an empty group claim is a claim on nothing

2026-09-12T14:36:54Z

A node that hosts no groups sends no `group_ids` on its hub socket, and the hub resolved the claim with `set(claimed_groups or authorized)` — so "I host nothing" arrived as "I host every group this account belongs to", other members' included. Such a node can serve none of them: it holds no GEK, and its own handshake refuses them with "Group not hosted on this node". `/v1/groups/{id}/nodes` answers in registration order and `_node_groups` is in-memory, so which node a client was sent to depended on who reconnected first after a hub restart. GroupPage took `nodes[0]` with no fallback. On 2026-09-11 a hub deploy at 20:14 reshuffled the registry, a second member's unconfigured node won the race, and a group stopped opening for everyone in it with its only real host online throughout. Any member could take one of their groups down, by accident, by leaving an empty node running. Four changes, because no one of them is sufficient: - the hub never widens an absent claim, and `update_groups` goes through the same ceiling as registration — it assigned its list verbatim, so the bound that makes C2 hold at authentication was one message wide - the node states the empty set rather than omitting the field - the refusal carries `not_hosted`, so a client can tell "try the next node" from "you, here, must do something first" - GroupPage walks the list instead of indexing into it The three lines involved date from 13, 20 and 23 August and each is defensible alone. The defect is in the seam, which is where the last two also were: a falsy empty collection must never mean "unspecified". Co-Authored-By: Claude Opus 5 Claude-Session: https://claude.ai/code/session_01T4YmK41VsEURWFdop4EEeT

meshbay.git/packages/meshbay-node/tests/test_hub_ws_group_claim.py, branch main

style: ruff's own fixes, mechanically applied

fix: an empty group claim is a claim on nothing