Add option to skip loading experiment position presets

.gitignore

@@ -121,3 +121,6 @@ hutch_python/tests/tst/db.txt
 
 # unit test artifacts
 *.sqlite
+
+# ignore _version.py
+_version.py

docs/source/upcoming_release_notes/409-Add_option_to_skip_loading_experiment_position_presets.rst

@@ -0,0 +1,22 @@
+409 Add option to skip loading experiment position presets
+#################
+
+API Changes
+-----------
+- N/A
+
+Features
+--------
+- Added an option (available in conf.yml) to skip loading experiment motor position presets.
+
+Bugfixes
+--------
+- N/A
+
+Maintenance
+-----------
+- N/A
+
+Contributors
+------------
+janeliu-slac

docs/source/yaml_files.rst

@@ -4,7 +4,8 @@ Yaml Files
 ``hutch-python`` uses a ``conf.yml`` file for basic configuration. This is a
 standard yaml file with the following valid keys:
 ``hutch``, ``db``, ``load``, ``load_level``, ``experiment``, ``obj_config``,
-``daq_type``, ``daq_host``, and ``daq_platform``, ``exclude_devices``.
+``daq_type``, ``daq_host``, ``daq_platform``, ``exclude_devices``,
+``additional_devices``, and ``load_experiment_presets``.
 
 
 hutch
@@ -179,7 +180,7 @@ at load time. The list uses the following format:
 
 
 additional_devices
-------------
+------------------
 The ``additional_devices`` key is optional. This key allows hutch-python to
 load additional devices that are on a different beamline or in a different
 hutch/area. The first entry below ``additional_devices`` is a search name,
@@ -212,6 +213,45 @@ In the example below hutch-python will load all devices from "tmo_sqr1_search",
          name: crix_*
 
 
+load_experiment_presets
+-----------------------
+The ``load_experiment_presets`` key determines whether hutch-python loads
+position presets for the active experiment. It takes a boolean value.
+
+Position presets are saved locations that can be called by commands such as
+``motor.mv_sample()``. Hutch-python supports two types of position presets.
+
+- Beamline presets are permanent positions shared across experiments.
+- Experiment presets are temporary positions associated with the active
+  experiment.
+
+.. code-block:: YAML
+
+   load_experiment_presets: false
+
+When set to ``false``, hutch-python still loads beamline presets. It does not
+configure or read the active experiment's preset directory. This can improve
+startup performance when the experiment directory contains many preset files.
+
+When set to ``true``, hutch-python makes both beamline and active experiment
+presets available.
+
+.. code-block:: YAML
+
+   load_experiment_presets: true
+
+The default is ``true``. Existing configurations that omit this key retain
+their current behavior.
+
+Use the unquoted YAML values ``true`` and ``false``. Quoted values such as
+``"false"`` are strings rather than Boolean values and are invalid for this
+setting.
+
+This setting affects only position presets. It does not disable loading the
+experiment Python file, questionnaire objects, or other experiment
+configuration.
+
+
 Full File Example
 -----------------
 

hutch_python/constants.py

@@ -40,7 +40,8 @@
     'obj_config',
     'session_timer',
     'exclude_devices',
-    'additional_devices'
+    'additional_devices',
+    'load_experiment_presets'
 )
 NO_LOG_EXCEPTIONS = (KeyboardInterrupt, SystemExit)
 LOG_DOMAINS = {".pcdsn", ".slac.stanford.edu"}

hutch_python/load_conf.py

@@ -582,26 +582,57 @@ def load_conf(conf, hutch_dir=None, args=None):
             all_objects='Namespace of all loaded objects.',
         )
 
-    # Install Presets
+    # Configure saved motor positions. Presets are stored as YAML files under
+    # the hutch launch directory.
     if hutch_dir is not None:
+        # Log preset setup failures without stopping the entire session.
         with safe_load('position presets'):
             presets_dir = Path(hutch_dir) / 'presets'
+
+            # Beamline presets are permanent and shared by all experiments.
             beamline_presets = presets_dir / 'beamline'
+
+            # Preserve existing behavior unless the YAML configuration file
+            # explicitly disables experiment presets.
+            load_experiment_presets = conf.get('load_experiment_presets', True)
+            if not isinstance(load_experiment_presets, bool):
+                logger.error(
+                    'Invalid load_experiment_presets value %r; expected "true" '
+                    'or "false". Experiment presets will be loaded.',
+                    load_experiment_presets,
+                )
+                load_experiment_presets = True
+
+            # Preset root and permanent beamline directory are required.
             preset_paths = [presets_dir, beamline_presets]
-            if experiment is not None:
+
+            # Experiment presets are motor positions associated with the active
+            # experiment. Configure them only when an experiment is available
+            # and experiment preset loading is enabled.
+            if experiment is not None and load_experiment_presets:
                 experiment_presets = presets_dir / raw_expname
                 preset_paths.append(experiment_presets)
+
+            # Create any missing preset directories.
             for path in preset_paths:
                 if not path.exists():
                     path.mkdir()
                     path.chmod(0o777)
-            if experiment is None:
-                setup_preset_paths(hutch=beamline_presets,
-                                   defer_loading=True)
+
+            # Make both permanent beamline presets and active experiment
+            # presets available.
+            if experiment is not None and load_experiment_presets:
+                setup_preset_paths(
+                    hutch=beamline_presets,
+                    exp=experiment_presets,
+                    defer_loading=True,
+                )
             else:
-                setup_preset_paths(hutch=beamline_presets,
-                                   exp=experiment_presets,
-                                   defer_loading=True)
+                # Make only permanent beamline presets available.
+                setup_preset_paths(
+                    hutch=beamline_presets,
+                    defer_loading=True,
+                )
 
     # configure objects
     if obj_config is not None:

hutch_python/tests/test_load_conf.py

@@ -34,6 +34,63 @@ def test_file_load():
     assert len(Presets._paths) == 2
 
 
+def test_experiment_presets_disabled(monkeypatch, tmp_path):
+    # Check that an active experiment doesn't allow experiment presets to
+    # be configured when the setting is disabled.
+    setup_calls = []
+
+    def mock_setup_preset_paths(**kwargs):
+        setup_calls.append(kwargs)
+    monkeypatch.setattr(
+        'hutch_python.load_conf.setup_preset_paths',
+        mock_setup_preset_paths,
+    )
+    monkeypatch.setattr(
+        'hutch_python.load_conf.get_qs_objs',
+        lambda expname: {},
+    )
+    monkeypatch.setattr(
+        'hutch_python.load_conf.get_exp_objs',
+        lambda expname: SimpleNamespace(),
+    )
+    load_conf(
+        {
+            'hutch': 'tst',
+            'experiment': 'tstx010',
+            'load_experiment_presets': False,
+            'daq_type': 'nodaq',
+        },
+        hutch_dir=tmp_path,
+    )
+    beamline_path = tmp_path / 'presets' / 'beamline'
+    experiment_path = tmp_path / 'presets' / 'x010'
+    assert setup_calls == [{
+        'hutch': beamline_path,
+        'defer_loading': True,
+    }]
+    assert beamline_path.is_dir()
+    assert not experiment_path.exists()
+
+
+def test_presets_without_experiment(monkeypatch, tmp_path):
+    setup_calls = []
+    monkeypatch.setattr(
+        'hutch_python.load_conf.setup_preset_paths',
+        lambda **kwargs: setup_calls.append(kwargs),
+    )
+    load_conf(
+        {
+            'load_experiment_presets': True,
+            'daq_type': 'nodaq',
+        },
+        hutch_dir=tmp_path,
+    )
+    assert setup_calls == [{
+        'hutch': tmp_path / 'presets' / 'beamline',
+        'defer_loading': True,
+    }]
+
+
 def test_exp_override():
     logger.debug('test_exp_override')
     set_sim_mode(True)