diff --git a/exordos_core/compute/builders/pool.py b/exordos_core/compute/builders/pool.py
index 9db304a9..2733d287 100644
--- a/exordos_core/compute/builders/pool.py
+++ b/exordos_core/compute/builders/pool.py
@@ -299,10 +299,21 @@ def _actualize_machine_derivatives_on_create_update(
             # Don't swith boot mode for the core set as the update procedure
             # is performed by guest machine driver.
             if not self._is_core_machine(machine):
-                _, guest_actual = machine_guest_pair
+                guest_target, guest_actual = machine_guest_pair
+                # A machine that is still being installed has asked for a
+                # network boot and has not reported back yet. Any update
+                # that reaches it meanwhile (an element re-rendering its
+                # node, say) must not take it out of that boot mode: it
+                # would be rebuilt off a disk Seed OS never wrote.
+                if (
+                    guest_actual is None
+                    and guest_target.boot == nc.BootAlternative.network
+                ):
+                    boot = nc.BootAlternative.network.value
+                    port = models.Port.from_boot_network()
                 # The image is changed, so the machine should be booted in the
                 # `network` boot mode and flashed with a new image.
-                if guest_actual and guest_actual.image != resolved_image:
+                elif guest_actual and guest_actual.image != resolved_image:
                     boot = nc.BootAlternative.network.value
                     # Any port for the boot network is fine. The port will be replaced
                     # after the machine is flashed and switched to the main network.
diff --git a/exordos_core/tests/unit/compute/test_pool_builder_boot.py b/exordos_core/tests/unit/compute/test_pool_builder_boot.py
new file mode 100644
index 00000000..2935727e
--- /dev/null
+++ b/exordos_core/tests/unit/compute/test_pool_builder_boot.py
@@ -0,0 +1,102 @@
+#    Copyright 2026 Genesis Corporation.
+#
+#    All Rights Reserved.
+#
+#    Licensed under the Apache License, Version 2.0 (the "License"); you may
+#    not use this file except in compliance with the License. You may obtain
+#    a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#    License for the specific language governing permissions and limitations
+#    under the License.
+
+"""Which boot mode an update leaves a machine in (compute/builders/pool)."""
+
+from unittest import mock
+import uuid as sys_uuid
+
+import pytest
+
+from exordos_core.compute import constants as nc
+from exordos_core.compute.builders import pool as pool_builder
+
+IMAGE = "http://repo/exordos-base.raw.zst"
+
+
+@pytest.fixture
+def builder():
+    return pool_builder.PoolBuilderService.__new__(pool_builder.PoolBuilderService)
+
+
+def _machine(name="worker-a"):
+    machine = mock.MagicMock()
+    machine.uuid = sys_uuid.uuid4()
+    machine.name = name
+    machine.node.uuid = sys_uuid.uuid4()
+    return machine
+
+
+def _guest(boot, image=IMAGE):
+    guest = mock.MagicMock()
+    guest.boot = boot
+    guest.image = image
+    return guest
+
+
+def _derivatives(builder, machine, guest_pair):
+    port, volume = mock.MagicMock(), mock.MagicMock()
+    volume.image = IMAGE
+    with (
+        mock.patch.object(
+            builder, "_get_or_fetch_machine_ctx", return_value=(port, volume)
+        ),
+        mock.patch.object(pool_builder.ua_models, "UniversalAgent") as agent,
+        mock.patch.object(pool_builder.models.Port, "from_boot_network"),
+        mock.patch.object(
+            pool_builder.pool_models.PoolMachine, "from_machine_and_port"
+        ),
+        mock.patch.object(pool_builder.pool_models, "GuestMachine"),
+        mock.patch.object(builder, "_agent_by_pool", return_value=sys_uuid.uuid4()),
+    ):
+        agent.objects.get_one_or_none.return_value = mock.MagicMock()
+        builder._actualize_machine_derivatives_on_create_update(
+            machine, machine_guest_pair=guest_pair
+        )
+    return machine.boot
+
+
+def test_an_update_keeps_a_machine_that_is_still_installing_on_the_network(builder):
+    """Seed OS has not reported back yet: taking the machine off the network
+    boot would rebuild it from a disk nothing has written."""
+    machine = _machine()
+    boot = _derivatives(
+        builder, machine, guest_pair=(_guest(nc.BootAlternative.network), None)
+    )
+    assert boot == nc.BootAlternative.network.value
+
+
+def test_an_update_leaves_an_installed_machine_on_its_disk(builder):
+    machine = _machine()
+    boot = _derivatives(
+        builder,
+        machine,
+        guest_pair=(_guest(nc.BootAlternative.hd0), _guest(nc.BootAlternative.hd0)),
+    )
+    assert boot == nc.BootAlternative.hd0.value
+
+
+def test_a_changed_image_sends_the_machine_back_to_the_network(builder):
+    machine = _machine()
+    boot = _derivatives(
+        builder,
+        machine,
+        guest_pair=(
+            _guest(nc.BootAlternative.hd0),
+            _guest(nc.BootAlternative.hd0, image="http://repo/other.raw.zst"),
+        ),
+    )
+    assert boot == nc.BootAlternative.network.value