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, 3 deletions

diff --git a/packages/meshbay-node/tests/test_windows_node_lifecycle.py b/packages/meshbay-node/tests/test_windows_node_lifecycle.py
index 6ca301b..d98fd01 100644
--- a/packages/meshbay-node/tests/test_windows_node_lifecycle.py
+++ b/packages/meshbay-node/tests/test_windows_node_lifecycle.py
@@ -314,9 +314,10 @@ def test_signing_in_sets_up_this_machines_node():
     assert "process.platform !== 'win32' || !hasBundledNode()" in ensure
     # A node set up for someone else is left as it is...
     assert ensure.index("return { state: 'other_account' }") < ensure.index("provisionNode(")
-    # ...and so is an account already linked to another node.
-    assert "if (linked && linked !== p.pk_node_ed25519) return { state: 'other_node' };" in ensure
-    assert ensure.index("state: 'other_node'") < ensure.index("linkNodeKeyAndAwaitRunning(")
+    # An account with nodes on other machines keeps them: this one's key is
+    # added beside theirs, so there is no other node to protect from it.
+    assert "other_node" not in ensure
+    assert "linkNodeKeyAndAwaitRunning(" in ensure
     # Started however this machine is set up, through the CLI like every start.
     assert "winNodeStartVia(['autostart', 'start'])" in ensure
     # One start at a time.