Phase 1 abgeschlossen: Node-Identitaet in Control Core verkabelt (§3.6, §6.3)

- NodeIdentity/NodeRole in hms_domain: persistente node_id aus
  userdata/identity, Rollen RENDER_NODE/COORDINATOR/CONTROL_DESK,
  plausible Kombinationen validiert, keine Auto-Leader-Wahl (§6.3)
- Control Core: create_app(identity) injizierbar; Dev-Modus ephemeral;
  Registry registriert eigene Node; neue Endpunkte /system/identity
  (ohne Secrets, §27.1) und /cluster/nodes (UI-Kategorien §6.3)
- 16 neue/aktualisierte Integrationstests; Gesamtsuite 199 gruen

tests/unit/test_node_identity.py

@@ -0,0 +1,96 @@
+"""Unit-Tests Node-Identität und Rollen (PLAN.md §3.6, §6.3, §10.1)."""
+
+from __future__ import annotations
+
+import uuid
+from pathlib import Path
+
+import pytest
+from hms_domain import NodeIdentity, NodeRole
+
+
+def _roles(*r: NodeRole) -> frozenset[NodeRole]:
+    return frozenset(r)
+
+
+# ---------- Persistenz (§3.6, §6.3) ----------
+
+
+def test_load_or_create_persists_across_restart(tmp_path: Path) -> None:
+    identity_dir = tmp_path / "userdata" / "identity"
+    first = NodeIdentity.load_or_create(
+        identity_dir, "Show Server A", _roles(NodeRole.RENDER_NODE, NodeRole.COORDINATOR)
+    )
+    second = NodeIdentity.load_or_create(
+        identity_dir, "Show Server A", _roles(NodeRole.RENDER_NODE, NodeRole.COORDINATOR)
+    )
+    assert first.node_id == second.node_id  # persistente node_id (§3.6)
+    uuid.UUID(first.node_id)  # gültige UUID
+
+
+def test_identity_file_location_per_spec(tmp_path: Path) -> None:
+    """node_id liegt unter userdata/identity/ (§9-Struktur)."""
+    identity_dir = tmp_path / "userdata" / "identity"
+    NodeIdentity.load_or_create(identity_dir, "N", _roles(NodeRole.RENDER_NODE))
+    assert (identity_dir / "node_id").is_file()
+
+
+def test_two_nodes_get_distinct_persistent_ids(tmp_path: Path) -> None:
+    a = NodeIdentity.load_or_create(tmp_path / "a", "Node A", _roles(NodeRole.RENDER_NODE))
+    b = NodeIdentity.load_or_create(tmp_path / "b", "Node B", _roles(NodeRole.RENDER_NODE))
+    assert a.node_id != b.node_id  # doppelte node_id wäre Fehler (§6.3)
+
+
+# ---------- Rollen (§6.3) ----------
+
+
+@pytest.mark.parametrize(
+    "roles",
+    [
+        _roles(NodeRole.RENDER_NODE),
+        _roles(NodeRole.COORDINATOR),
+        _roles(NodeRole.CONTROL_DESK),
+        _roles(NodeRole.RENDER_NODE, NodeRole.COORDINATOR),
+        _roles(NodeRole.CONTROL_DESK, NodeRole.COORDINATOR),
+    ],
+)
+def test_valid_role_combinations_accepted(roles) -> None:
+    identity = NodeIdentity.ephemeral("Test Node", roles)
+    assert identity.roles == roles
+
+
+@pytest.mark.parametrize(
+    "roles",
+    [
+        frozenset(),  # keine Rolle
+        _roles(NodeRole.RENDER_NODE, NodeRole.CONTROL_DESK),  # Desk + Renderer unplausibel
+    ],
+)
+def test_invalid_role_combinations_rejected(roles) -> None:
+    with pytest.raises(ValueError):
+        NodeIdentity.ephemeral("Test Node", roles)
+
+
+def test_role_properties() -> None:
+    render_only = NodeIdentity.ephemeral("R", _roles(NodeRole.RENDER_NODE))
+    coord_only = NodeIdentity.ephemeral("C", _roles(NodeRole.COORDINATOR))
+    both = NodeIdentity.ephemeral("B", _roles(NodeRole.RENDER_NODE, NodeRole.COORDINATOR))
+    assert render_only.renders_locally and not render_only.is_coordinator
+    assert coord_only.is_coordinator and not coord_only.renders_locally
+    assert both.is_coordinator and both.renders_locally  # §6.3: Coordinator auf Render-Node
+
+
+def test_display_name_editable_without_identity_change(tmp_path: Path) -> None:
+    """Umbenennung ändert die node_id nicht (§10.1: Name ist kein Identitätsteil
+    für Parameterpfade)."""
+    identity_dir = tmp_path / "identity"
+    a = NodeIdentity.load_or_create(identity_dir, "Alter Name", _roles(NodeRole.RENDER_NODE))
+    b = NodeIdentity.load_or_create(identity_dir, "Neuer Name", _roles(NodeRole.RENDER_NODE))
+    assert a.node_id == b.node_id
+    assert a.display_name != b.display_name
+
+
+def test_ephemeral_distinct_ids() -> None:
+    a = NodeIdentity.ephemeral("A", _roles(NodeRole.RENDER_NODE))
+    b = NodeIdentity.ephemeral("B", _roles(NodeRole.RENDER_NODE))
+    assert a.node_id != b.node_id  # Tests dürfen niemals dieselbe ID teilen