fix: bound what one member can cost the others

2026-09-12T14:36:54Z

An availability review, prompted by the group claim above: a participant supplies input — who else bears the cost? Six answers where the cost fell on someone other than the sender, and none of them needs an attacker. AV3 `chat_notify` carried a `group_id` the hub believed, so any connected node could write a notification to every member of any group on the hub, carrying a display string of its choosing, with its account having no relation to that group. This is the group claim again, two hundred lines further down the same socket. Gated on what the node is registered for, and metered: the fan-out is one write per member. The budget expires by time rather than on disconnect, or reconnecting would refill it and a node token is good for an hour. AV4 A swarm source named its own `endpoint` as free text documented as "ip:port", so an account could publish a third party's address — H6's `peer_ip` defect, never applied here. Nothing dials a swarm source today, which is the only reason it was not already a reflection primitive. It is a transport and a port now, never a host, and the number of hashes one account may claim is bounded: rows were keyed (hash, account) with no cap at all. AV5 `handle_webrtc_answer` resolved any pending `peer_id` from any node's socket. The answer is the SDP a browser then connects to. That this had not happened rested on a uuid4 being unguessable. AV6 `relay_register` had no authentication of any kind: it compared `pk_relay` against the approved value, which is a *public* key, so anyone who could read it could rewrite where the hub tells nodes to send relayed traffic. The module docstring promised signed JWTs and `jwt` was imported and never used. AV7 The node held unlimited peer connections and kept one that never completed a handshake for the life of the daemon. H6 bounded what one unauthenticated peer costs; the hub's cap is three offers in flight per *account*, a limit on each caller and not on the machine, so an operator's exposure grew with the size of their groups. AV8 `invite-notify` put a request-supplied `group_name` into the subject of an email the hub sends under its own domain, to any account, with no rate limit. The name comes from the group row now. The tests are two accounts each, in one file that says why: a one-member test proves a one-member property, and every finding here needed a second person to exist at all. Each was checked against the unfixed code. Two did not survive that check and were rewritten — one re-enacted the disconnect path instead of running it (hence `forget_node`), the other called the reaper itself and would have passed with the call removed from `handle_offer`. Co-Authored-By: Claude Opus 5 Claude-Session: https://claude.ai/code/session_01T4YmK41VsEURWFdop4EEeT

meshbay.git/packages/meshbay-node/tests/test_peer_session_limits.py, branch 0.14

fix: bound what one member can cost the others