feat(hub): one account, several linked nodes

An account links up to MAX_NODES_PER_ACCOUNT node keys (node_keys table)
instead of the one users.pk_node_ed25519; the migration carries each
account's key over and the downgrade keeps the last one linked.
/v1/nodes/auth accepts any linked key, and its token names the key that
won it (nk). PUT /me/node_key adds a key, idempotently, 409 past the
limit; DELETE /me/node_key names the key: a browser session any of its
own, a node only its own. Unlinking a key closes that node's socket and
refuses its tokens at once, on REST and on the socket; the account's other
nodes are untouched. /pubkeys no longer gives a node key to other accounts,
and gives the caller its last linked one, which installed desktop apps read.

The node reports waiting_for_node_key while its key is unlinked and signs
in again as soon as the hub says so, so a key linked again is back within
seconds; unlinking itself signs in first to hold a token naming its key.

Profile -> Linked nodes lists each node (connected, last seen, IP, linked
since, This machine in the desktop app) with Copy and Unlink, and adds a
key by hand. The Node page banner, Create group and the desktop app add
this machine's key instead of replacing another's. Messages that pointed
at Settings -> Link Node point at Profile -> Linked nodes.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

1 files changed, 4 insertions, 2 deletions

diff --git a/packages/meshbay-hub/tests/test_node_auth.py b/packages/meshbay-hub/tests/test_node_auth.py
index fb05f9b..7b51d14 100644
--- a/packages/meshbay-hub/tests/test_node_auth.py
+++ b/packages/meshbay-hub/tests/test_node_auth.py
@@ -225,9 +225,11 @@ async def test_node_scope_allows_pubkey_lookup(client):
     r = await client.get("/v1/users/op4_test/pubkeys",
                          headers={"Authorization": f"Bearer {node_token}"})
     assert r.status_code == 200
-    # An account id and the node's linking key — no user identity keys (H3).
+    # An account id and no user identity keys (H3). Its own latest node key, for
+    # the desktop applications already installed; nobody else sees it.
     assert "pk_ed25519" not in r.json()
-    assert r.json()["pk_node_ed25519"] is not None
+    assert r.json()["username"] == "op4_test"
+    assert r.json()["pk_node_ed25519"]
 
 
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