feat(protocol): bind the MNP token to the node it is for (E10)

2026-09-26T00:03:50Z

The audience split stopped a member's node credential from opening the hub API. It did not stop the credential being *replayed to another node*: the MNP token carried the member's whole group set and named no node, so a token handed to node A's operator could be presented to node B the member also belongs to. That does not read content on B — the handshake still requires proving node B's group key, which the operator lacks — but it reaches B's pre-proof window and fetches the member's *encrypted* keypair bundle for B (offline-attackable, bounded, audited): a disclosure §2.4 says should not follow from hosting a member on A. The token now names the node it is minted for (a `node` claim = that node's Ed25519 key), and authorize_token refuses one that names a different key. The client already knows the target node's key (from /v1/groups/{id}/nodes) and asks for a token bound to it: POST /v1/nodes/mnp-token takes node_pk, and transport.connect threads it (group-page, the connection pool and rewrap pass n.pk_node; reconnect preserves it). A token that names no node is still accepted, because the hub only mints one for the authenticated requester, so an unbound token grants nothing across accounts — which also keeps non-binding callers working with no churn. Done before deploy, so it folds into the MNP 4.0 flag day rather than needing its own. Docs: §5.2, register E10, MESHBAY_NODE_PROTOCOL.md §6.3. test_handshake.py and test_mnp_token.py hold the binding (a token for node A is refused by node B, accepted by node A; an unbound token still works); red before, green after. common/node/hub suites green. Co-Authored-By: Claude Opus 4.8

fix(hub): present a node-audience token in the handshake, not the hub session token

2026-09-25T15:24:16Z

A member authenticated to a node in the MNP handshake with its hub *session* token — scope=user, valid at the hub API for hours. A node operator is in the threat model, so this handed them a live hub credential for the member: enough to enumerate the member's other groups, act as them, and (before the previous commit closed it) take the account over. The node genuinely needs a hub-signed membership assertion, so the fix is to make that a separate credential that opens nothing at the hub API. Two audiences signed by the one hub key (meshbay_common/tokens.py): - HUB_API_AUD — session tokens (login, device-auth, node-auth, refresh), used for hub calls and signaling. decode_access_token now binds this audience, so an MNP token cannot be replayed against the hub API. - MNP_AUD — a short-lived token a member presents to a node and nothing else, from POST /v1/nodes/mnp-token. authorize_token now binds this audience, so a session token presented to a node is refused. This closes the disclosure. The node's own self-decode (hub_client.py) reads its node token with audience=HUB_API_AUD. The client fetches the MNP token inside transport.connect() (and on every reconnect) using the session token, so callers are unchanged and signaling keeps using the session token. No regression to a long session: the MNP token is checked once, at the handshake, before any proof — a film already playing is not re-authenticated, so a 15-minute token does not interrupt a 4-hour film; reconnects refetch a fresh one. Denylist and membership checks are unchanged (the MNP token carries sub/jti/groups). Tests: authorize_token refuses a session/no-audience token and accepts an MNP token; the hub API refuses an MNP token; POST /v1/nodes/mnp-token is minted only for a member's own session. Verified red-before/green-after; common, node and hub suites green (the pre-existing test_cli_golden failure is an argparse/pytest prog artifact unrelated to this change). Still to do before deploy (B2): bump the MNP version and client.minimum so a stale desktop client is told to update rather than getting a handshake refusal, update docs/MESHBAY_DESIGN.md and MESHBAY_NODE_PROTOCOL.md, and validate against a real node locally, then deploy hub+node+SPA atomically. Co-Authored-By: Claude Opus 4.8

meshbay.git/packages/meshbay-hub/tests/test_mnp_token.py, branch main

feat(protocol): bind the MNP token to the node it is for (E10)

fix(hub): present a node-audience token in the handshake, not the hub session token