2 files changed, 82 insertions, 0 deletions
diff --git a/packages/meshbay-hub/src/meshbay_hub/db/migrations/versions/e5a2b7d31f88_user_device_auth_keys.py b/packages/meshbay-hub/src/meshbay_hub/db/migrations/versions/e5a2b7d31f88_user_device_auth_keys.py
new file mode 100644
index 0000000..ddada15
--- /dev/null
+++ b/packages/meshbay-hub/src/meshbay_hub/db/migrations/versions/e5a2b7d31f88_user_device_auth_keys.py
@@ -0,0 +1,47 @@
+"""user device auth keys
+
+Device Ed25519 authentication to the hub, so a client signs in without
+re-deriving a key from the passphrase every time.
+
+Deliberately **not** the key directory that was H3: nothing reads this but the
+hub itself, nobody wraps a group key for it, and it is a different key from the
+per-node identity keys, which never leave the device-node relationship. See
+`docs/desktop-client-v1.md` §5.
+
+`create_all()` is not a migration — it creates missing tables and never a
+missing column, so a schema change without a file here reaches the tests (fresh
+DB every run) and never reaches the deployed hub.
+
+Revision ID: e5a2b7d31f88
+Revises: 3dc91cd4ea52
+"""
+
+from typing import Sequence, Union
+
+import sqlalchemy as sa
+from alembic import op
+
+revision: str = "e5a2b7d31f88"
+down_revision: Union[str, Sequence[str], None] = "3dc91cd4ea52"
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    op.create_table(
+        "user_devices",
+        sa.Column("id", sa.String(36), primary_key=True),
+        sa.Column("user_id", sa.String(36), sa.ForeignKey("users.id"),
+                  nullable=False),
+        sa.Column("pk_auth_ed25519", sa.String(64), nullable=False, unique=True),
+        sa.Column("label", sa.String(64), nullable=False, server_default=""),
+        sa.Column("created_at", sa.DateTime(timezone=True), nullable=False,
+                  server_default=sa.func.now()),
+        sa.Column("last_seen", sa.DateTime(timezone=True), nullable=True),
+    )
+    op.create_index("ix_user_devices_user", "user_devices", ["user_id"])
+
+
+def downgrade() -> None:
+    op.drop_index("ix_user_devices_user", table_name="user_devices")
+    op.drop_table("user_devices")
diff --git a/packages/meshbay-hub/src/meshbay_hub/db/models.py b/packages/meshbay-hub/src/meshbay_hub/db/models.py
index a220a64..12507a6 100644
--- a/packages/meshbay-hub/src/meshbay_hub/db/models.py
+++ b/packages/meshbay-hub/src/meshbay_hub/db/models.py
@@ -178,6 +178,41 @@ class FederatedGroup(Base):
     )
 
 
+class UserDevice(Base):
+    """
+    A device's key for authenticating **to the hub**, and nothing else.
+
+    This is not a reintroduction of the key directory that was H3, and the
+    distinction is worth being precise about because it looks like one:
+
+      * **Nobody reads this but the hub.** No endpoint publishes it, nothing
+        wraps a group key for it, and no node ever asks for it. H3 was a
+        directory *others* read from, where a substituted key was handed the
+        GEK by an honest member.
+      * **It is not a node identity key.** Those are generated per node, pinned
+        there, and never leave that relationship (`docs/per-node-identity-v1.md`).
+        A device holds one of these *plus* a different key per node, so nothing
+        here correlates a person across operators.
+
+    What it does cost, stated plainly: the hub now knows how many devices an
+    account has and when each one last signed in. That is new metadata, and it
+    is the price of not deriving a key from the passphrase on every sign-in.
+    """
+
+    __tablename__ = "user_devices"
+
+    id:         Mapped[str] = mapped_column(String(36), primary_key=True, default=_uuid)
+    user_id:    Mapped[str] = mapped_column(ForeignKey("users.id"), nullable=False)
+    # base64 raw Ed25519, unique so one device key belongs to one account
+    pk_auth_ed25519: Mapped[str] = mapped_column(String(64), unique=True, nullable=False)
+    label:      Mapped[str] = mapped_column(String(64), default="")
+    created_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), default=_now)
+    last_seen:  Mapped[datetime | None] = mapped_column(
+        DateTime(timezone=True), nullable=True)
+
+    __table_args__ = (Index("ix_user_devices_user", "user_id"),)
+
+
 class SwarmSource(Base):
     """
     Tracks which nodes can serve a given content hash (public swarm).