diff --git a/craft_application/__init__.py b/craft_application/__init__.py
index 8c46c00d1..48fe2f7cf 100644
--- a/craft_application/__init__.py
+++ b/craft_application/__init__.py
@@ -30,6 +30,7 @@
     ServiceFactory,
 )
 from craft_application._config import ConfigModel
+from craft_application.util import is_managed_mode
 
 try:
     from ._version import __version__
@@ -54,4 +55,5 @@
     "PackageService",
     "ProviderService",
     "ServiceFactory",
+    "is_managed_mode",
 ]
diff --git a/craft_application/application.py b/craft_application/application.py
index 8faf06541..16a28b0ba 100644
--- a/craft_application/application.py
+++ b/craft_application/application.py
@@ -25,6 +25,7 @@
 import subprocess
 import sys
 import traceback
+import warnings
 from collections.abc import Iterable, Sequence
 from dataclasses import dataclass, field
 from functools import cached_property
@@ -33,6 +34,7 @@
 
 import craft_cli
 import craft_parts
+import craft_platforms
 import craft_providers
 from craft_parts.plugins.plugins import PluginType
 from platformdirs import user_cache_path
@@ -152,7 +154,7 @@ def __init__(
         # This may be overridden by specific application implementations.
         self.project_dir = pathlib.Path.cwd()
 
-        if self.is_managed():
+        if util.is_managed_mode():
             self._work_dir = pathlib.Path("/root")
         else:
             self._work_dir = pathlib.Path.cwd()
@@ -280,7 +282,7 @@ def _merge_defaults(
     @property
     def log_path(self) -> pathlib.Path | None:
         """Get the path to this process's log file, if any."""
-        if self.is_managed():
+        if util.is_managed_mode():
             return util.get_managed_logpath(self.app)
         return None
 
@@ -381,7 +383,7 @@ def get_project(
         with project_path.open() as file:
             yaml_data = util.safe_yaml_load(file)
 
-        host_arch = util.get_host_architecture()
+        host_arch = craft_platforms.DebianArchitecture.from_host().value
         build_planner = self.app.BuildPlannerClass.from_yaml_data(
             yaml_data, project_path
         )
@@ -432,7 +434,13 @@ def project(self) -> models.Project:
 
     def is_managed(self) -> bool:
         """Shortcut to tell whether we're running in managed mode."""
-        return self.services.get_class("provider").is_managed()
+        warnings.warn(
+            DeprecationWarning(
+                "app.is_managed is deprecated. Use craft_application.is_managed_mode() instead."
+            ),
+            stacklevel=2,
+        )
+        return util.is_managed_mode()
 
     def run_managed(self, platform: str | None, build_for: str | None) -> None:
         """Run the application in a managed instance."""
@@ -604,7 +612,7 @@ def _pre_run(self, dispatcher: craft_cli.Dispatcher) -> None:
         # Some commands might have a project_dir parameter. Those commands and
         # only those commands should get a project directory, but only when
         # not managed.
-        if self.is_managed():
+        if util.is_managed_mode():
             self.project_dir = pathlib.Path("/root/project")
         elif project_dir := getattr(args, "project_dir", None):
             self.project_dir = pathlib.Path(project_dir).expanduser().resolve()
@@ -669,7 +677,7 @@ def _run_inner(self) -> int:
             # command runs in the outer instance
             craft_cli.emit.debug(f"Running {self.app.name} {command.name} on host")
             return_code = dispatcher.run() or os.EX_OK
-        elif not self.is_managed():
+        elif not util.is_managed_mode():
             # command runs in inner instance, but this is the outer instance
             self.run_managed(platform, build_for)
             return_code = os.EX_OK
@@ -735,7 +743,7 @@ def _emit_error(
             error.__cause__ = cause
 
         # Do not report the internal logpath if running inside an instance
-        if self.is_managed():
+        if util.is_managed_mode():
             error.logpath_report = False
 
         craft_cli.emit.error(error)
@@ -843,7 +851,7 @@ def _set_global_environment(self, info: craft_parts.ProjectInfo) -> None:
     def _render_secrets(self, yaml_data: dict[str, Any]) -> None:
         """Render build-secrets, in-place."""
         secret_values = secrets.render_secrets(
-            yaml_data, managed_mode=self.is_managed()
+            yaml_data, managed_mode=util.is_managed_mode()
         )
 
         num_secrets = len(secret_values.secret_strings)
diff --git a/craft_application/services/fetch.py b/craft_application/services/fetch.py
index f50edda46..93c885e9f 100644
--- a/craft_application/services/fetch.py
+++ b/craft_application/services/fetch.py
@@ -84,7 +84,7 @@ def setup(self) -> None:
         """Start the fetch-service process with proper arguments."""
         super().setup()
 
-        if not self._services.get_class("provider").is_managed():
+        if not util.is_managed_mode():
             # Early fail if the fetch-service is not installed.
             fetch.verify_installed()
 
@@ -153,7 +153,7 @@ def create_project_manifest(self, artifacts: list[pathlib.Path]) -> None:
 
         Only supports a single generated artifact, and only in managed runs.
         """
-        if not self._services.ProviderClass.is_managed():
+        if not util.is_managed_mode():
             emit.debug("Unable to generate the project manifest on the host.")
             return
 
diff --git a/craft_application/services/provider.py b/craft_application/services/provider.py
index 4405bc3f1..6ffa51ee0 100644
--- a/craft_application/services/provider.py
+++ b/craft_application/services/provider.py
@@ -24,6 +24,7 @@
 import pkgutil
 import sys
 import urllib.request
+import warnings
 from collections.abc import Generator, Iterable
 from pathlib import Path
 from typing import TYPE_CHECKING
@@ -85,7 +86,13 @@ def __init__(
     @classmethod
     def is_managed(cls) -> bool:
         """Determine whether we're running in managed mode."""
-        return os.getenv(cls.managed_mode_env_var) == "1"
+        warnings.warn(
+            DeprecationWarning(
+                "ProviderService.is_managed() is deprecated. Use craft_application.is_managed_mode() instead."
+            ),
+            stacklevel=2,
+        )
+        return util.is_managed_mode()
 
     def setup(self) -> None:
         """Application-specific service setup."""
@@ -223,7 +230,7 @@ def get_provider(self, name: str | None = None) -> craft_providers.Provider:
         if self._provider is not None:
             return self._provider
 
-        if self.is_managed():
+        if util.is_managed_mode():
             raise CraftError("Cannot nest managed environments.")
 
         # (1) use provider specified in the function argument,
diff --git a/craft_application/util/platforms.py b/craft_application/util/platforms.py
index 8deee64ea..8e6fc26b3 100644
--- a/craft_application/util/platforms.py
+++ b/craft_application/util/platforms.py
@@ -20,9 +20,11 @@
 import functools
 import os
 import platform
+import warnings
 from typing import Final
 
-from craft_parts.utils import os_utils
+import craft_platforms
+import distro
 from craft_providers import bases
 
 from .string import strtobool
@@ -33,8 +35,13 @@
 @functools.lru_cache(maxsize=1)
 def get_host_architecture() -> str:
     """Get host architecture in deb format."""
-    machine = platform.machine()
-    return _ARCH_TRANSLATIONS_PLATFORM_TO_DEB.get(machine, machine)
+    warnings.warn(
+        DeprecationWarning(
+            "get_host_architecture() is deprecated. Use craft_platforms.DebianArchitecture.from_host()"
+        ),
+        stacklevel=2,
+    )
+    return craft_platforms.DebianArchitecture.from_host().value
 
 
 def convert_architecture_deb_to_platform(arch: str) -> str:
@@ -54,10 +61,16 @@ def is_valid_architecture(arch: str) -> bool:
 @functools.lru_cache(maxsize=1)
 def get_host_base() -> bases.BaseName:
     """Get the craft-providers base for the running host."""
-    release = os_utils.OsRelease()
-    os_id = release.id()
-    version_id = release.version_id()
-    return bases.BaseName(os_id, version_id)
+    warnings.warn(
+        PendingDeprecationWarning(
+            "get_host_base() is pending deprecation. Use craft_platforms.DistroBase.from_linux_distribution(distro.LinuxDistribution())"
+        ),
+        stacklevel=2,
+    )
+    distro_base = craft_platforms.DistroBase.from_linux_distribution(
+        distro.LinuxDistribution(include_lsb=False, include_uname=False)
+    )
+    return bases.BaseName(distro_base.distribution, distro_base.series)
 
 
 def get_hostname(hostname: str | None = None) -> str:
diff --git a/craft_application/util/string.py b/craft_application/util/string.py
index 2913afa12..549fe6c7e 100644
--- a/craft_application/util/string.py
+++ b/craft_application/util/string.py
@@ -31,7 +31,7 @@ def strtobool(value: str) -> bool:
     value = value.strip().lower()
     if value in {"true", "t", "yes", "y", "on", "1"}:
         return True
-    if value in {"false", "f", "no", "n", "off", "0"}:
+    if value in {"false", "f", "no", "n", "off", "0", "", "none"}:
         return False
     raise ValueError(f"Invalid boolean value: {value}")
 
diff --git a/docs/conf.py b/docs/conf.py
index 527df7a9b..e9273ec10 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -39,7 +39,15 @@
 
 extensions = [
     "canonical_sphinx",
+    "sphinx.ext.intersphinx",
 ]
+
+intersphinx_mapping = {
+    "craft-platforms": (
+        "https://canonical-craft-platforms.readthedocs-hosted.com/en/latest",
+        None,
+    )
+}
 # endregion
 
 # region Options for extensions
diff --git a/docs/reference/changelog.rst b/docs/reference/changelog.rst
index fc026206d..82206fdd6 100644
--- a/docs/reference/changelog.rst
+++ b/docs/reference/changelog.rst
@@ -4,6 +4,27 @@
 Changelog
 *********
 
+4.10.0 (YYYY-Mon-DD)
+--------------------
+
+Application
+===========
+
+- Deprecate ``Application.is_managed()`` in favour of :func:`is_managed_mode()`
+
+Services
+========
+
+- Deprecate ``ProviderService.is_managed()`` in favour of :func:`is_managed_mode()`
+
+Utilities
+=========
+
+- Deprecate ``get_host_architecture()`` in favour of
+  :external+craft-platforms:meth:`craft_platforms.DebianArchitecture.from_host()`
+- Warn that ``get_host_base()`` is pending deprecation in favour of
+  :external+craft-platforms:meth:`craft_platforms.DistroBase.from_linux_distribution()`
+
 4.9.1 (2025-Feb-12)
 -------------------
 
@@ -23,7 +44,7 @@ Application
 ===========
 
 - Add a feature to allow `Python plugins
-  https://packaging.python.org/en/latest/guides/creating-and-discovering-plugins/>`_
+  <https://packaging.python.org/en/latest/guides/creating-and-discovering-plugins/>`_
   to extend or modify the behaviour of applications that use craft-application as a
   framework. The plugin packages must be installed in the same virtual environment
   as the application.
diff --git a/tests/conftest.py b/tests/conftest.py
index d0643ad02..29983872a 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -21,12 +21,14 @@
 import pathlib
 import shutil
 import subprocess
+import warnings
 from dataclasses import dataclass
 from importlib import metadata
 from typing import TYPE_CHECKING, Any
 from unittest.mock import Mock
 
 import craft_parts
+import craft_platforms
 import jinja2
 import pydantic
 import pytest
@@ -45,8 +47,12 @@
 
 def _create_fake_build_plan(num_infos: int = 1) -> list[models.BuildInfo]:
     """Create a build plan that is able to execute on the running system."""
-    arch = util.get_host_architecture()
-    base = util.get_host_base()
+    with warnings.catch_warnings():
+        warnings.simplefilter("ignore", DeprecationWarning)
+        arch = util.get_host_architecture()
+    with warnings.catch_warnings():
+        warnings.simplefilter("ignore", PendingDeprecationWarning)
+        base = util.get_host_base()
     return [models.BuildInfo("foo", arch, arch, base)] * num_infos
 
 
@@ -133,7 +139,7 @@ def app_metadata_docs(features) -> craft_application.AppMetadata:
 
 @pytest.fixture
 def fake_project() -> models.Project:
-    arch = util.get_host_architecture()
+    arch = craft_platforms.DebianArchitecture.from_host().value
     return models.Project(
         name="full-project",  # pyright: ignore[reportArgumentType]
         title="A fully-defined project",  # pyright: ignore[reportArgumentType]
@@ -161,7 +167,7 @@ def fake_build_plan(request) -> list[models.BuildInfo]:
 @pytest.fixture
 def full_build_plan(mocker) -> list[models.BuildInfo]:
     """A big build plan with multiple bases and build-for targets."""
-    host_arch = util.get_host_architecture()
+    host_arch = craft_platforms.DebianArchitecture.from_host().value
     build_plan = []
     for release in ("20.04", "22.04", "24.04"):
         build_plan.extend(
@@ -280,6 +286,8 @@ def pack(
         def metadata(self) -> models.BaseMetadata:
             return models.BaseMetadata()
 
+    services.ServiceFactory.register("package", FakePackageService)
+
     return FakePackageService
 
 
@@ -305,6 +313,7 @@ def __init__(
                 **kwargs,
             )
 
+    services.ServiceFactory.register("lifecycle", FakeLifecycleService)
     return FakeLifecycleService
 
 
@@ -314,6 +323,7 @@ class FakeInitService(services.InitService):
         def _get_loader(self, template_dir: pathlib.Path) -> jinja2.BaseLoader:
             return FileSystemLoader(tmp_path / "templates" / template_dir)
 
+    services.ServiceFactory.register("init", FakeInitService)
     return FakeInitService
 
 
@@ -324,6 +334,7 @@ class FakeRemoteBuild(services.RemoteBuildService):
         def _get_lp_client(self) -> launchpad.Launchpad:
             return Mock(spec=launchpad.Launchpad)
 
+    services.ServiceFactory.register("remote_build", FakeRemoteBuild)
     return FakeRemoteBuild
 
 
@@ -337,10 +348,6 @@ def fake_services(
     fake_init_service_class,
     fake_remote_build_service_class,
 ):
-    services.ServiceFactory.register("package", fake_package_service_class)
-    services.ServiceFactory.register("lifecycle", fake_lifecycle_service_class)
-    services.ServiceFactory.register("init", fake_init_service_class)
-    services.ServiceFactory.register("remote_build", fake_remote_build_service_class)
     factory = services.ServiceFactory(app_metadata, project=fake_project)
     factory.update_kwargs(
         "lifecycle", work_dir=tmp_path, cache_dir=tmp_path / "cache", build_plan=[]
diff --git a/tests/integration/services/test_service_factory.py b/tests/integration/services/test_service_factory.py
index d48240b5f..0ded2b077 100644
--- a/tests/integration/services/test_service_factory.py
+++ b/tests/integration/services/test_service_factory.py
@@ -28,12 +28,11 @@ def test_gets_dataclass_services(
     fake_lifecycle_service_class,
     fake_provider_service_class,
 ):
+    services.ServiceFactory.register("lifecycle", fake_lifecycle_service_class)
+    services.ServiceFactory.register("provider", fake_provider_service_class)
     factory = services.ServiceFactory(
         app_metadata,
         project=fake_project,
-        PackageClass=fake_package_service_class,
-        LifecycleClass=fake_lifecycle_service_class,
-        ProviderClass=fake_provider_service_class,
     )
 
     check.is_instance(factory.package, services.PackageService)
@@ -49,7 +48,6 @@ def test_gets_registered_services(
     fake_lifecycle_service_class,
     fake_provider_service_class,
 ):
-    services.ServiceFactory.register("package", fake_package_service_class)
     services.ServiceFactory.register("lifecycle", fake_lifecycle_service_class)
     services.ServiceFactory.register("provider", fake_provider_service_class)
     factory = services.ServiceFactory(
@@ -63,10 +61,10 @@ def test_gets_registered_services(
 
 
 def test_real_service_error(app_metadata, fake_project):
+    services.ServiceFactory.register("package", services.PackageService)
     factory = services.ServiceFactory(
         app_metadata,
         project=fake_project,
-        PackageClass=services.PackageService,
     )
 
     with pytest.raises(
diff --git a/tests/integration/test_application.py b/tests/integration/test_application.py
index 406ee327a..5853c2284 100644
--- a/tests/integration/test_application.py
+++ b/tests/integration/test_application.py
@@ -29,7 +29,7 @@
 from craft_application.util import yaml
 
 
-class TestableApplication(craft_application.Application):
+class FakeApplication(craft_application.Application):
     """An application modified for integration tests.
 
     Modifications are:
@@ -38,7 +38,7 @@ class TestableApplication(craft_application.Application):
 
     def _pre_run(self, dispatcher: craft_cli.Dispatcher) -> None:
         super()._pre_run(dispatcher)
-        if self.is_managed():
+        if util.is_managed_mode():
             self.project_dir = pathlib.Path.cwd()
 
 
@@ -47,10 +47,8 @@ def create_app(app_metadata, fake_package_service_class):
     def _inner():
         # Create a factory without a project, to simulate a real application use
         # and force loading from disk.
-        services = craft_application.ServiceFactory(
-            app_metadata, PackageClass=fake_package_service_class
-        )
-        return TestableApplication(app_metadata, services)
+        services = craft_application.ServiceFactory(app_metadata)
+        return FakeApplication(app_metadata, services)
 
     return _inner
 
@@ -143,7 +141,7 @@ class _FakeCommand(craft_application.commands.AppCommand):
     ids=lambda ordered: f"keep_order={ordered}",
 )
 def test_registering_new_commands(
-    app: TestableApplication,
+    app: FakeApplication,
     monkeypatch: pytest.MonkeyPatch,
     capsys: pytest.CaptureFixture[str],
     *,
@@ -456,7 +454,7 @@ def test_build_secrets_managed(
     app = setup_secrets_project(destructive_mode=False)
 
     monkeypatch.setenv("CRAFT_MANAGED_MODE", "1")
-    assert app.is_managed()
+    assert util.is_managed_mode()
     app._work_dir = tmp_path
 
     # Before running the application, configure its environment "as if" the host app
diff --git a/tests/unit/services/test_fetch.py b/tests/unit/services/test_fetch.py
index 51748b2fe..bdae19639 100644
--- a/tests/unit/services/test_fetch.py
+++ b/tests/unit/services/test_fetch.py
@@ -37,7 +37,7 @@
 from craft_providers import bases
 from freezegun import freeze_time
 
-from craft_application import ProviderService, fetch, services
+from craft_application import fetch, services, util
 from craft_application.models import BuildInfo
 from craft_application.services import fetch as service_module
 
@@ -180,7 +180,7 @@ def test_warning_experimental(mocker, fetch_service, run_on_host, emitter):
     mocker.patch.object(fetch, "start_service")
     mocker.patch.object(fetch, "verify_installed")
     mocker.patch.object(fetch, "_get_service_base_dir", return_value=pathlib.Path())
-    mocker.patch.object(ProviderService, "is_managed", return_value=not run_on_host)
+    mocker.patch.object(util, "is_managed_mode", return_value=not run_on_host)
 
     fetch_service.setup()
 
@@ -197,7 +197,7 @@ def test_warning_experimental(mocker, fetch_service, run_on_host, emitter):
 def test_setup_managed(mocker, fetch_service):
     """The fetch-service process should only be checked/started when running on the host."""
     mock_start = mocker.patch.object(fetch, "start_service")
-    mocker.patch.object(ProviderService, "is_managed", return_value=True)
+    mocker.patch.object(util, "is_managed_mode", return_value=True)
 
     fetch_service.setup()
 
diff --git a/tests/unit/services/test_provider.py b/tests/unit/services/test_provider.py
index f53f7dce3..f4ca14cc4 100644
--- a/tests/unit/services/test_provider.py
+++ b/tests/unit/services/test_provider.py
@@ -207,7 +207,10 @@ def test_is_managed(managed_value, expected, monkeypatch):
         provider.ProviderService.managed_mode_env_var, str(managed_value)
     )
 
-    assert provider.ProviderService.is_managed() == expected
+    with pytest.warns(
+        DeprecationWarning, match=r"ProviderService.is_managed\(\) is deprecated."
+    ):
+        assert provider.ProviderService.is_managed() == expected
 
 
 def test_forward_environment_variables(monkeypatch, provider_service):
@@ -307,20 +310,20 @@ def test_get_existing_provider(self, provider_service):
 
         assert provider_service.get_provider() == expected
 
-    def test_get_provider_managed_mode(self, provider_service):
+    def test_get_provider_managed_mode(self, provider_service, monkeypatch):
         """Raise an error when running in managed mode."""
         provider_service._provider = None
-        provider_service.is_managed = lambda: True
+        monkeypatch.setattr("craft_application.util.is_managed_mode", lambda: True)
 
         with pytest.raises(errors.CraftError) as raised:
             provider_service.get_provider()
 
         assert raised.value == errors.CraftError("Cannot nest managed environments.")
 
-    def test_get_provider_from_argument(self, provider_service, providers):
+    def test_get_provider_from_argument(self, provider_service, providers, monkeypatch):
         """(1) use provider specified in the function argument."""
         provider_service._provider = None
-        provider_service.is_managed = lambda: False
+        monkeypatch.setattr("craft_application.util.is_managed_mode", lambda: False)
 
         result = provider_service.get_provider(name=providers.name)
 
@@ -329,7 +332,7 @@ def test_get_provider_from_argument(self, provider_service, providers):
     def test_get_provider_from_env(self, monkeypatch, provider_service, providers):
         """(2) get the provider from the environment (CRAFT_BUILD_ENVIRONMENT)."""
         provider_service._provider = None
-        provider_service.is_managed = lambda: False
+        monkeypatch.setattr("craft_application.util.is_managed_mode", lambda: False)
         monkeypatch.setenv("CRAFT_BUILD_ENVIRONMENT", providers.name)
 
         result = provider_service.get_provider()
@@ -339,7 +342,7 @@ def test_get_provider_from_env(self, monkeypatch, provider_service, providers):
     def test_get_provider_from_snap(self, mocker, provider_service, providers):
         """(3) use provider specified with snap configuration."""
         provider_service._provider = None
-        provider_service.is_managed = lambda: False
+        mocker.patch("craft_application.util.is_managed_mode", return_value=False)
         mocker.patch(
             "craft_application.services.provider.snap_config.get_snap_config",
             return_value=snap_config.SnapConfig(provider=providers.name),
@@ -354,7 +357,7 @@ def test_get_provider_no_snap_config(self, mocker, provider_service, emitter):
 
         Instead, proceed to the next step."""
         provider_service._provider = None
-        provider_service.is_managed = lambda: False
+        mocker.patch("craft_application.util.is_managed_mode", return_value=False)
         mocker.patch(
             "craft_application.services.provider.snap_config.get_snap_config",
             return_value=None,
diff --git a/tests/unit/test_application.py b/tests/unit/test_application.py
index 4956711c3..90b203bea 100644
--- a/tests/unit/test_application.py
+++ b/tests/unit/test_application.py
@@ -33,6 +33,7 @@
 
 import craft_cli
 import craft_parts
+import craft_platforms
 import craft_providers
 import pydantic
 import pytest
@@ -60,12 +61,11 @@
     get_other_command_group,
 )
 from craft_application.models import BuildInfo
-from craft_application.util import (
-    get_host_architecture,  # pyright: ignore[reportGeneralTypeIssues]
-)
 from tests.conftest import FakeApplication
 from tests.unit.conftest import BASIC_PROJECT_YAML
 
+HOST_ARCH = craft_platforms.DebianArchitecture.from_host().value
+
 EMPTY_COMMAND_GROUP = craft_cli.CommandGroup("FakeCommands", [])
 
 FULL_PROJECT_YAML = """
@@ -505,9 +505,7 @@ def test_merge_default_commands_only(app):
     [(True, pathlib.PurePosixPath("/tmp/testcraft.log")), (False, None)],
 )
 def test_log_path(monkeypatch, app, provider_managed, expected):
-    monkeypatch.setattr(
-        app.services.get_class("provider"), "is_managed", lambda: provider_managed
-    )
+    monkeypatch.setattr(util, "is_managed_mode", lambda: provider_managed)
 
     actual = app.log_path
 
@@ -520,9 +518,8 @@ def test_run_managed_success(mocker, app, fake_project, fake_build_plan):
     app.project = fake_project
     app._build_plan = fake_build_plan
     mock_pause = mocker.spy(craft_cli.emit, "pause")
-    arch = get_host_architecture()
 
-    app.run_managed(None, arch)
+    app.run_managed(None, HOST_ARCH)
 
     assert (
         mock.call(
@@ -544,7 +541,7 @@ def test_run_managed_failure(app, fake_project, fake_build_plan):
     app._build_plan = fake_build_plan
 
     with pytest.raises(craft_providers.ProviderError) as exc_info:
-        app.run_managed(None, get_host_architecture())
+        app.run_managed(None, HOST_ARCH)
 
     assert exc_info.value.brief == "Failed to execute testcraft in instance."
 
@@ -584,7 +581,7 @@ def test_run_managed_secrets(
         secret_strings=set(),
     )
 
-    app.run_managed(None, get_host_architecture())
+    app.run_managed(None, HOST_ARCH)
 
     # Check that the encoded secrets were propagated to the managed instance.
     assert len(mock_execute.mock_calls) == 1
@@ -604,7 +601,7 @@ def test_run_managed_multiple(app, fake_project):
     app.services.provider = mock_provider
     app.set_project(fake_project)
 
-    arch = get_host_architecture()
+    arch = HOST_ARCH
     info1 = BuildInfo("a1", arch, "arch1", bases.BaseName("base", "1"))
     info2 = BuildInfo("a2", arch, "arch2", bases.BaseName("base", "2"))
     app._build_plan = [info1, info2]
@@ -624,7 +621,7 @@ def test_run_managed_specified_arch(app, fake_project):
     app.services.provider = mock_provider
     app.set_project(fake_project)
 
-    arch = get_host_architecture()
+    arch = HOST_ARCH
     info1 = BuildInfo("a1", arch, "arch1", bases.BaseName("base", "1"))
     info2 = BuildInfo("a2", arch, "arch2", bases.BaseName("base", "2"))
     app._build_plan = [info1, info2]
@@ -644,7 +641,7 @@ def test_run_managed_specified_platform(app, fake_project):
     app.services.provider = mock_provider
     app.set_project(fake_project)
 
-    arch = get_host_architecture()
+    arch = HOST_ARCH
     info1 = BuildInfo("a1", arch, "arch1", bases.BaseName("base", "1"))
     info2 = BuildInfo("a2", arch, "arch2", bases.BaseName("base", "2"))
     app._build_plan = [info1, info2]
@@ -717,9 +714,7 @@ def test_get_arg_or_config(monkeypatch, app, parsed_args, environ, item, expecte
 def test_get_dispatcher_error(
     monkeypatch, check, capsys, app, mock_dispatcher, managed, error, exit_code, message
 ):
-    monkeypatch.setattr(
-        app.services.get_class("provider"), "is_managed", lambda: managed
-    )
+    monkeypatch.setattr(util, "is_managed_mode", lambda: managed)
     mock_dispatcher.pre_parse_args.side_effect = error
 
     with pytest.raises(SystemExit) as exc_info:
@@ -838,8 +833,8 @@ def test_set_verbosity_from_env_incorrect(monkeypatch, capsys, app):
     assert craft_cli.emit._mode == craft_cli.EmitterMode.BRIEF
 
 
-def test_pre_run_project_dir_managed(app):
-    app.is_managed = lambda: True
+def test_pre_run_project_dir_managed(monkeypatch, app):
+    monkeypatch.setattr(util, "is_managed_mode", lambda: True)
     dispatcher = mock.Mock(spec_set=craft_cli.Dispatcher)
 
     app._pre_run(dispatcher)
@@ -908,7 +903,7 @@ def test_run_success_managed(monkeypatch, app, fake_project, mocker):
 def test_run_success_managed_with_arch(monkeypatch, app, fake_project, mocker):
     mocker.patch.object(app, "get_project", return_value=fake_project)
     app.run_managed = mock.Mock()
-    arch = get_host_architecture()
+    arch = HOST_ARCH
     monkeypatch.setattr(sys, "argv", ["testcraft", "pull", f"--build-for={arch}"])
 
     pytest_check.equal(app.run(), 0)
@@ -932,12 +927,12 @@ def test_run_success_managed_with_platform(monkeypatch, app, fake_project, mocke
         ([], mock.call(None, None)),
         (["--platform=s390x"], mock.call("s390x", None)),
         (
-            ["--platform", get_host_architecture()],
-            mock.call(get_host_architecture(), None),
+            ["--platform", HOST_ARCH],
+            mock.call(HOST_ARCH, None),
         ),
         (
-            ["--build-for", get_host_architecture()],
-            mock.call(None, get_host_architecture()),
+            ["--build-for", HOST_ARCH],
+            mock.call(None, HOST_ARCH),
         ),
         (["--build-for", "s390x"], mock.call(None, "s390x")),
         (["--platform", "s390x,riscv64"], mock.call("s390x", None)),
@@ -1311,7 +1306,7 @@ def test_work_dir_project_non_managed(monkeypatch, app_metadata, fake_services):
     app = application.Application(app_metadata, fake_services)
     assert app._work_dir == pathlib.Path.cwd()
 
-    project = app.get_project(build_for=get_host_architecture())
+    project = app.get_project(build_for=HOST_ARCH)
 
     # Make sure the project is loaded correctly (from the cwd)
     assert project is not None
@@ -1326,7 +1321,7 @@ def test_work_dir_project_managed(monkeypatch, app_metadata, fake_services):
     app = application.Application(app_metadata, fake_services)
     assert app._work_dir == pathlib.PosixPath("/root")
 
-    project = app.get_project(build_for=get_host_architecture())
+    project = app.get_project(build_for=HOST_ARCH)
 
     # Make sure the project is loaded correctly (from the cwd)
     assert project is not None
@@ -1378,7 +1373,7 @@ def test_expand_environment_build_for_all(
             base: ubuntu@24.04
             platforms:
               platform1:
-                build-on: [{util.get_host_architecture()}]
+                build-on: [{HOST_ARCH}]
                 build-for: [all]
             parts:
               mypart:
@@ -1397,12 +1392,12 @@ def test_expand_environment_build_for_all(
     # Make sure the project is loaded correctly (from the cwd)
     assert project is not None
     assert project.parts["mypart"]["build-environment"] == [
-        {"BUILD_ON": util.get_host_architecture()},
-        {"BUILD_FOR": util.get_host_architecture()},
+        {"BUILD_ON": HOST_ARCH},
+        {"BUILD_FOR": HOST_ARCH},
     ]
     emitter.assert_debug(
         "Expanding environment variables with the host architecture "
-        f"{util.get_host_architecture()!r} as the build-for architecture "
+        f"{HOST_ARCH!r} as the build-for architecture "
         "because 'all' was specified."
     )
 
@@ -1410,14 +1405,14 @@ def test_expand_environment_build_for_all(
 @pytest.mark.usefixtures("environment_project")
 def test_application_expand_environment(app_metadata, fake_services):
     app = application.Application(app_metadata, fake_services)
-    project = app.get_project(build_for=get_host_architecture())
+    project = app.get_project(build_for=HOST_ARCH)
 
     # Make sure the project is loaded correctly (from the cwd)
     assert project is not None
     assert project.parts["mypart"]["source-tag"] == "v1.2.3"
     assert project.parts["mypart"]["build-environment"] == [
-        {"BUILD_ON": util.get_host_architecture()},
-        {"BUILD_FOR": util.get_host_architecture()},
+        {"BUILD_ON": HOST_ARCH},
+        {"BUILD_FOR": HOST_ARCH},
     ]
 
 
@@ -1456,7 +1451,7 @@ def test_application_build_secrets(app_metadata, fake_services, monkeypatch, moc
     spied_set_secrets = mocker.spy(craft_cli.emit, "set_secrets")
 
     app = application.Application(app_metadata, fake_services)
-    project = app.get_project(build_for=get_host_architecture())
+    project = app.get_project(build_for=HOST_ARCH)
 
     # Make sure the project is loaded correctly (from the cwd)
     assert project is not None
@@ -1571,7 +1566,7 @@ def test_extra_yaml_transform(tmp_path, app_metadata, fake_services):
     app.project_dir = tmp_path
     _ = app.get_project(build_for="s390x")
 
-    assert app.build_on == util.get_host_architecture()
+    assert app.build_on == HOST_ARCH
     assert app.build_for == "s390x"
 
 
@@ -1587,7 +1582,7 @@ def test_mandatory_adoptable_fields(tmp_path, app_metadata, fake_services):
     app.project_dir = tmp_path
 
     with pytest.raises(errors.CraftValidationError) as exc_info:
-        _ = app.get_project(build_for=get_host_architecture())
+        _ = app.get_project(build_for=HOST_ARCH)
 
     assert (
         str(exc_info.value)
@@ -1748,18 +1743,18 @@ def test_process_grammar_to_all(tmp_path, app_metadata, fake_services):
         base: ubuntu@24.04
         platforms:
           myplatform:
-            build-on: [{util.get_host_architecture()}]
+            build-on: [{HOST_ARCH}]
             build-for: [all]
         parts:
           mypart:
             plugin: nil
             build-packages:
             - test-package
-            - on {util.get_host_architecture()} to all:
+            - on {HOST_ARCH} to all:
               - on-host-to-all
             - to all:
               - to-all
-            - on {util.get_host_architecture()} to s390x:
+            - on {HOST_ARCH} to s390x:
               - on-host-to-s390x
             - to s390x:
               - on-amd64-to-s390x
@@ -1869,7 +1864,7 @@ def test_process_yaml_from_extra_transform(
     ]
     assert project.parts["mypart"]["build-environment"] == [
         # evaluate project variables
-        {"hello": get_host_architecture()},
+        {"hello": HOST_ARCH},
         # render secrets
         {"MY_VAR": "secret-value"},
     ]
@@ -1919,7 +1914,7 @@ def environment_partitions_project(monkeypatch, tmp_path):
 @pytest.mark.usefixtures("environment_partitions_project")
 def test_partition_application_expand_environment(app_metadata, fake_services):
     app = FakePartitionsApplication(app_metadata, fake_services)
-    project = app.get_project(build_for=get_host_architecture())
+    project = app.get_project(build_for=HOST_ARCH)
 
     assert craft_parts.Features().enable_partitions is True
     # Make sure the project is loaded correctly (from the cwd)
@@ -2168,7 +2163,7 @@ def test_clean_platform(monkeypatch, tmp_path, app_metadata, fake_services, mock
     """Test that calling "clean --platform=x" correctly filters the build plan."""
     data = util.safe_yaml_load(StringIO(BASIC_PROJECT_YAML))
     # Put a few different platforms on the project
-    arch = util.get_host_architecture()
+    arch = HOST_ARCH
     build_on_for = {
         "build-on": [arch],
         "build-for": [arch],
diff --git a/tests/unit/util/test_string.py b/tests/unit/util/test_string.py
index 36953a1ea..8916cff4d 100644
--- a/tests/unit/util/test_string.py
+++ b/tests/unit/util/test_string.py
@@ -52,6 +52,8 @@
         ("Off", False),
         ("0", False),
         ("0  ", False),
+        ("", False),
+        (" ", False),
     ],
 )
 def test_strtobool(data, expected):
@@ -66,8 +68,6 @@ def test_strtobool(data, expected):
         (None),
         ({}),
         ([]),
-        (""),
-        (" "),
         ("invalid"),
         ("2"),
         ("-"),