diff --git a/brainbox/processing.py b/brainbox/processing.py
index a20cb1222..79b769abb 100644
--- a/brainbox/processing.py
+++ b/brainbox/processing.py
@@ -1,17 +1,16 @@
-'''
-Processes data from one form into another, e.g. taking spike times and binning them into
-non-overlapping bins and convolving spike times with a gaussian kernel.
-'''
+"""Process data from one form into another.
+
+For example, taking spike times and binning them into non-overlapping bins and convolving spike
+times with a gaussian kernel.
+"""
 
 import numpy as np
 import pandas as pd
 from scipy import interpolate, sparse
 from brainbox import core
-from iblutil.numerical import bincount2D as _bincount2D
+from iblutil.numerical import bincount2D
 from iblutil.util import Bunch
 import logging
-import warnings
-import traceback
 
 _logger = logging.getLogger(__name__)
 
@@ -118,35 +117,6 @@ def sync(dt, times=None, values=None, timeseries=None, offsets=None, interp='zer
     return syncd
 
 
-def bincount2D(x, y, xbin=0, ybin=0, xlim=None, ylim=None, weights=None):
-    """
-    Computes a 2D histogram by aggregating values in a 2D array.
-
-    :param x: values to bin along the 2nd dimension (c-contiguous)
-    :param y: values to bin along the 1st dimension
-    :param xbin:
-        scalar: bin size along 2nd dimension
-        0: aggregate according to unique values
-        array: aggregate according to exact values (count reduce operation)
-    :param ybin:
-        scalar: bin size along 1st dimension
-        0: aggregate according to unique values
-        array: aggregate according to exact values (count reduce operation)
-    :param xlim: (optional) 2 values (array or list) that restrict range along 2nd dimension
-    :param ylim: (optional) 2 values (array or list) that restrict range along 1st dimension
-    :param weights: (optional) defaults to None, weights to apply to each value for aggregation
-    :return: 3 numpy arrays MAP [ny,nx] image, xscale [nx], yscale [ny]
-    """
-    for line in traceback.format_stack():
-        print(line.strip())
-    warning_text = """Future warning: bincount2D() is now a part of iblutil.
-                    brainbox.processing.bincount2D will be removed in future versions.
-                    Please replace imports with iblutil.numerical.bincount2D."""
-    _logger.warning(warning_text)
-    warnings.warn(warning_text, FutureWarning)
-    return _bincount2D(x, y, xbin, ybin, xlim, ylim, weights)
-
-
 def compute_cluster_average(spike_clusters, spike_var):
     """
     Quickish way to compute the average of some quantity across spikes in each cluster given
@@ -197,7 +167,7 @@ def bin_spikes(spikes, binsize, interval_indices=False):
 
 
 def get_units_bunch(spks_b, *args):
-    '''
+    """
     Returns a bunch, where the bunch keys are keys from `spks` with labels of spike information
     (e.g. unit IDs, times, features, etc.), and the values for each key are arrays with values for
     each unit: these arrays are ordered and can be indexed by unit id.
@@ -223,18 +193,18 @@ def get_units_bunch(spks_b, *args):
     --------
     1) Create a units bunch given a spikes bunch, and get the amps for unit #4 from the units
     bunch.
-        >>> import brainbox as bb
-        >>> import alf.io as aio
+        >>> from brainbox import processing
+        >>> import one.alf.io as alfio
         >>> import ibllib.ephys.spikes as e_spks
         (*Note, if there is no 'alf' directory, make 'alf' directory from 'ks2' output directory):
         >>> e_spks.ks2_to_alf(path_to_ks_out, path_to_alf_out)
-        >>> spks_b = aio.load_object(path_to_alf_out, 'spikes')
-        >>> units_b = bb.processing.get_units_bunch(spks_b)
+        >>> spks_b = alfio.load_object(path_to_alf_out, 'spikes')
+        >>> units_b = processing.get_units_bunch(spks_b)
         # Get amplitudes for unit 4.
         >>> amps = units_b['amps']['4']
 
     TODO add computation time estimate?
-    '''
+    """
 
     # Initialize `units`
     units_b = Bunch()
@@ -261,7 +231,7 @@ def get_units_bunch(spks_b, *args):
 
 
 def filter_units(units_b, t, **kwargs):
-    '''
+    """
     Filters units according to some parameters. **kwargs are the keyword parameters used to filter
     the units.
 
@@ -299,24 +269,24 @@ def filter_units(units_b, t, **kwargs):
     Examples
     --------
     1) Filter units according to the default parameters.
-        >>> import brainbox as bb
-        >>> import alf.io as aio
+        >>> from brainbox import processing
+        >>> import one.alf.io as alfio
         >>> import ibllib.ephys.spikes as e_spks
         (*Note, if there is no 'alf' directory, make 'alf' directory from 'ks2' output directory):
         >>> e_spks.ks2_to_alf(path_to_ks_out, path_to_alf_out)
         # Get a spikes bunch, units bunch, and filter the units.
-        >>> spks_b = aio.load_object(path_to_alf_out, 'spikes')
-        >>> units_b = bb.processing.get_units_bunch(spks_b, ['times', 'amps', 'clusters'])
+        >>> spks_b = alfio.load_object(path_to_alf_out, 'spikes')
+        >>> units_b = processing.get_units_bunch(spks_b, ['times', 'amps', 'clusters'])
         >>> T = spks_b['times'][-1] - spks_b['times'][0]
-        >>> filtered_units = bb.processing.filter_units(units_b, T)
+        >>> filtered_units = processing.filter_units(units_b, T)
 
     2) Filter units with no minimum amplitude, a minimum firing rate of 1 Hz, and a max false
     positive rate of 0.2, given a refractory period of 2 ms.
-        >>> filtered_units  = bb.processing.filter_units(units_b, T, min_amp=0, min_fr=1)
+        >>> filtered_units  = processing.filter_units(units_b, T, min_amp=0, min_fr=1)
 
     TODO: `units_b` input arg could eventually be replaced by `clstrs_b` if the required metrics
           are in `clstrs_b['metrics']`
-    '''
+    """
 
     # Set params
     params = {'min_amp': 50e-6, 'min_fr': 0.5, 'max_fpr': 0.2, 'rp': 0.002}  # defaults
diff --git a/brainbox/tests/test_processing.py b/brainbox/tests/test_processing.py
index 970aaeb34..d136d3d1f 100644
--- a/brainbox/tests/test_processing.py
+++ b/brainbox/tests/test_processing.py
@@ -1,7 +1,6 @@
 from brainbox import processing, core
 import unittest
 import numpy as np
-import datetime
 
 
 class TestProcessing(unittest.TestCase):
@@ -63,15 +62,6 @@ def test_sync(self):
         self.assertTrue(times2.min() >= resamp2.times.min())
         self.assertTrue(times2.max() <= resamp2.times.max())
 
-    def test_bincount2D_deprecation(self):
-        # Timer to remove bincount2D (now in iblutil)
-        # Once this test fails:
-        # - Remove the bincount2D method in processing.py
-        # - Remove the import from iblutil at the top of that file
-        # - Delete this test
-        if datetime.datetime.now() > datetime.datetime(2024, 6, 30):
-            raise NotImplementedError
-
     def test_compute_cluster_averag(self):
         # Create fake data for 3 clusters
         clust1 = np.ones(40)
@@ -103,11 +93,6 @@ def test_compute_cluster_averag(self):
         self.assertEqual(avg_val[2], 0.75)
         self.assertTrue(np.all(count == (40, 40, 50)))
 
-    def test_deprecations(self):
-        """Ensure removal of bincount2D function."""
-        from datetime import datetime
-        self.assertTrue(datetime.today() < datetime(2024, 8, 1), 'remove brainbox.processing.bincount2D')
-
 
 if __name__ == '__main__':
     np.random.seed(0)
diff --git a/ibllib/io/extractors/mesoscope.py b/ibllib/io/extractors/mesoscope.py
index b258af3ab..ebaeb7e91 100644
--- a/ibllib/io/extractors/mesoscope.py
+++ b/ibllib/io/extractors/mesoscope.py
@@ -51,6 +51,7 @@ def patch_imaging_meta(meta: dict) -> dict:
         for fov in meta.get('FOV', []):
             if 'roiUuid' in fov:
                 fov['roiUUID'] = fov.pop('roiUuid')
+    assert 'nFrames' in meta, '"nFrames" key missing from meta data; rawImagingData.meta.json likely an old version'
     return meta
 
 
@@ -753,6 +754,15 @@ def get_timeshifts(raw_imaging_meta):
         Calculate the time shifts for each field of view (FOV) and the relative offsets for each
         scan line.
 
+        For a 2 scan field, 2 depth recording (so 4 FOVs):
+
+        Frame 1, lines 1-512 correspond to FOV_00
+        Frame 1, lines 551-1062 correspond to FOV_01
+        Frame 2, lines 1-512 correspond to FOV_02
+        Frame 2, lines 551-1062 correspond to FOV_03
+        Frame 3, lines 1-512 correspond to FOV_00
+        ...
+
         Parameters
         ----------
         raw_imaging_meta : dict
@@ -772,26 +782,27 @@ def get_timeshifts(raw_imaging_meta):
         FOVs = raw_imaging_meta['FOV']
 
         # Double-check meta extracted properly
-        raw_meta = raw_imaging_meta['rawScanImageMeta']
-        artist = raw_meta['Artist']
-        assert sum(x['enable'] for x in artist['RoiGroups']['imagingRoiGroup']['rois']) == len(FOVs)
-
+        # assert meta.FOV.Zs is ascending but use slice_id field. This may not be necessary but is expected.
+        slice_ids = np.array([fov['slice_id'] for fov in FOVs])
+        assert np.all(np.diff([x['Zs'] for x in FOVs]) >= 0), 'FOV depths not in ascending order'
+        assert np.all(np.diff(slice_ids) >= 0), 'slice IDs not ordered'
         # Number of scan lines per FOV, i.e. number of Y pixels / image height
         n_lines = np.array([x['nXnYnZ'][1] for x in FOVs])
-        n_valid_lines = np.sum(n_lines)  # Number of lines imaged excluding flybacks
-        # Number of lines during flyback
-        n_lines_per_gap = int((raw_meta['Height'] - n_valid_lines) / (len(FOVs) - 1))
-        # The start and end indices of each FOV in the raw images
-        fov_start_idx = np.insert(np.cumsum(n_lines[:-1] + n_lines_per_gap), 0, 0)
-        fov_end_idx = fov_start_idx + n_lines
-        line_period = raw_imaging_meta['scanImageParams']['hRoiManager']['linePeriod']
-
-        line_indices = []
-        fov_time_shifts = fov_start_idx * line_period
-        line_time_shifts = []
 
-        for ln, s, e in zip(n_lines, fov_start_idx, fov_end_idx):
-            line_indices.append(np.arange(s, e))
-            line_time_shifts.append(np.arange(0, ln) * line_period)
+        # We get indices from MATLAB extracted metadata so below two lines are no longer needed
+        # n_valid_lines = np.sum(n_lines)  # Number of lines imaged excluding flybacks
+        # n_lines_per_gap = int((raw_meta['Height'] - n_valid_lines) / (len(FOVs) - 1))  # N lines during flyback
+        line_period = raw_imaging_meta['scanImageParams']['hRoiManager']['linePeriod']
+        frame_time_shifts = slice_ids / raw_imaging_meta['scanImageParams']['hRoiManager']['scanFrameRate']
+
+        # Line indices are now extracted by the MATLAB function mesoscopeMetadataExtraction.m
+        # They are indexed from 1 so we subtract 1 to convert to zero-indexed
+        line_indices = [np.array(fov['lineIdx']) - 1 for fov in FOVs]  # Convert to zero-indexed from MATLAB 1-indexed
+        assert all(lns.size == n for lns, n in zip(line_indices, n_lines)), 'unexpected number of scan lines'
+        # The start indices of each FOV in the raw images
+        fov_start_idx = np.array([lns[0] for lns in line_indices])
+        roi_time_shifts = fov_start_idx * line_period   # The time offset for each FOV
+        fov_time_shifts = roi_time_shifts + frame_time_shifts
+        line_time_shifts = [(lns - ln0) * line_period for lns, ln0 in zip(line_indices, fov_start_idx)]
 
         return line_indices, fov_time_shifts, line_time_shifts
diff --git a/ibllib/pipes/local_server.py b/ibllib/pipes/local_server.py
index 6574f88f1..cf3f76437 100644
--- a/ibllib/pipes/local_server.py
+++ b/ibllib/pipes/local_server.py
@@ -152,7 +152,7 @@ def job_creator(root_path, one=None, dry=False, rerun=False):
     return pipes, all_datasets
 
 
-def task_queue(mode='all', lab=None, alyx=None):
+def task_queue(mode='all', lab=None, alyx=None, env=(None,)):
     """
     Query waiting jobs from the specified Lab
 
@@ -164,12 +164,18 @@ def task_queue(mode='all', lab=None, alyx=None):
         Lab name as per Alyx, otherwise try to infer from local Globus install.
     alyx : one.webclient.AlyxClient
         An Alyx instance.
+    env : list
+        One or more environments to filter by. See :prop:`ibllib.pipes.tasks.Task.env`.
 
     Returns
     -------
     list of dict
         A list of Alyx tasks associated with `lab` that have a 'Waiting' status.
     """
+    def predicate(task):
+        classe = tasks.str2class(task['executable'])
+        return (mode == 'all' or classe.job_size == mode) and classe.env in env
+
     alyx = alyx or AlyxClient(cache_rest=None)
     if lab is None:
         _logger.debug('Trying to infer lab from globus installation')
@@ -179,28 +185,12 @@ def task_queue(mode='all', lab=None, alyx=None):
         return  # if the lab is none, this will return empty tasks each time
     data_repo = get_local_data_repository(alyx)
     # Filter for tasks
-    tasks_all = alyx.rest('tasks', 'list', status='Waiting',
-                          django=f'session__lab__name__in,{lab},data_repository__name,{data_repo}', no_cache=True)
-    if mode == 'all':
-        waiting_tasks = tasks_all
-    else:
-        small_jobs = []
-        large_jobs = []
-        for t in tasks_all:
-            strmodule, strclass = t['executable'].rsplit('.', 1)
-            classe = getattr(importlib.import_module(strmodule), strclass)
-            job_size = classe.job_size
-            if job_size == 'small':
-                small_jobs.append(t)
-            else:
-                large_jobs.append(t)
-    if mode == 'small':
-        waiting_tasks = small_jobs
-    elif mode == 'large':
-        waiting_tasks = large_jobs
-
+    waiting_tasks = alyx.rest('tasks', 'list', status='Waiting',
+                              django=f'session__lab__name__in,{lab},data_repository__name,{data_repo}', no_cache=True)
+    # Filter tasks by size
+    filtered_tasks = filter(predicate, waiting_tasks)
     # Order tasks by priority
-    sorted_tasks = sorted(waiting_tasks, key=lambda d: d['priority'], reverse=True)
+    sorted_tasks = sorted(filtered_tasks, key=lambda d: d['priority'], reverse=True)
 
     return sorted_tasks
 
@@ -252,8 +242,7 @@ def tasks_runner(subjects_path, tasks_dict, one=None, dry=False, count=5, time_o
         if dry:
             print(session_path, tdict['name'])
         else:
-            task, dsets = tasks.run_alyx_task(tdict=tdict, session_path=session_path,
-                                              one=one, **kwargs)
+            task, dsets = tasks.run_alyx_task(tdict=tdict, session_path=session_path, one=one, **kwargs)
             if dsets:
                 all_datasets.extend(dsets)
                 c += 1
diff --git a/ibllib/pipes/mesoscope_tasks.py b/ibllib/pipes/mesoscope_tasks.py
index 906ab7f27..0f83cbe44 100644
--- a/ibllib/pipes/mesoscope_tasks.py
+++ b/ibllib/pipes/mesoscope_tasks.py
@@ -193,11 +193,12 @@ def _run(self, remove_uncompressed=False, verify_output=True, clobber=False, **k
 
 
 class MesoscopePreprocess(base_tasks.MesoscopeTask):
-    """Run suite2p preprocessing on tif files"""
+    """Run suite2p preprocessing on tif files."""
 
     priority = 80
     cpu = -1
     job_size = 'large'
+    env = 'suite2p'
 
     @property
     def signature(self):
@@ -426,10 +427,7 @@ def _consolidate_exptQC(exptQC):
 
         # Concatenate frames
         frameQC = np.concatenate([e['frameQC_frames'] for e in exptQC], axis=0)
-
-        # Transform to bad_frames as expected by suite2p
         bad_frames = np.where(frameQC != 0)[0]
-
         return frameQC, frameQC_names, bad_frames
 
     def get_default_tau(self):
@@ -555,7 +553,7 @@ def _run(self, run_suite2p=True, rename_files=True, use_badframes=True, **kwargs
         """ Metadata and parameters """
         # Load metadata and make sure all metadata is consistent across FOVs
         meta_files = sorted(self.session_path.glob(f'{self.device_collection}/*rawImagingData.meta.*'))
-        collections = set(f.parts[-2] for f in meta_files)
+        collections = sorted(set(f.parts[-2] for f in meta_files))
         # Check there is exactly 1 meta file per collection
         assert len(meta_files) == len(list(self.session_path.glob(self.device_collection))) == len(collections)
         rawImagingData = [mesoscope.patch_imaging_meta(alfio.load_file_content(filepath)) for filepath in meta_files]
@@ -576,19 +574,31 @@ def _run(self, run_suite2p=True, rename_files=True, use_badframes=True, **kwargs
         self.kwargs = {**self.kwargs, **db}
 
         """ Bad frames """
+        # exptQC.mat contains experimenter QC values that may not affect ROI detection (e.g. noises, pauses)
         qc_paths = (self.session_path.joinpath(f[1], 'exptQC.mat')
                     for f in self.input_files if f[0] == 'exptQC.mat')
         qc_paths = sorted(map(str, filter(Path.exists, qc_paths)))
         exptQC = [loadmat(p, squeeze_me=True, simplify_cells=True) for p in qc_paths]
         if len(exptQC) > 0:
-            frameQC, frameQC_names, bad_frames = self._consolidate_exptQC(exptQC)
+            frameQC, frameQC_names, _ = self._consolidate_exptQC(exptQC)
         else:
             _logger.warning('No frame QC (exptQC.mat) files found.')
-            frameQC, bad_frames = np.array([], dtype='u1'), np.array([], dtype='i8')
+            frameQC = np.array([], dtype='u1')
             frameQC_names = pd.DataFrame(columns=['qc_values', 'qc_labels'])
+
         # If applicable, save as bad_frames.npy in first raw_imaging_folder for suite2p
-        if len(bad_frames) > 0 and use_badframes is True:
-            np.save(Path(db['data_path'][0]).joinpath('bad_frames.npy'), bad_frames)
+        # badframes.mat contains QC values that do affect ROI detection (e.g. no PMT, lens artefacts)
+        badframes = np.array([], dtype='i8')
+        total_frames = 0
+        # Ensure all indices are relative to total cumulative frames
+        for m, collection in zip(rawImagingData, collections):
+            badframes_path = self.session_path.joinpath(collection, 'badframes.mat')
+            if badframes_path.exists():
+                raw_mat = loadmat(badframes_path, squeeze_me=True, simplify_cells=True)['badframes']
+                badframes = np.r_[badframes, raw_mat + total_frames]
+            total_frames += m['nFrames']
+        if len(badframes) > 0 and use_badframes is True:
+            np.save(Path(db['data_path'][0]).joinpath('bad_frames.npy'), badframes)
 
         """ Suite2p """
         # Create alf it is doesn't exist
@@ -625,10 +635,10 @@ def signature(self):
                             (f'_{self.sync_namespace}_DAQdata.timestamps.npy', self.sync_collection, True),
                             (f'_{self.sync_namespace}_DAQdata.meta.json', self.sync_collection, True),
                             ('_ibl_rawImagingData.meta.json', self.device_collection, True),
-                            ('rawImagingData.times_scanImage.npy', self.device_collection, True),
+                            ('rawImagingData.times_scanImage.npy', self.device_collection, True, True),  # register raw
                             (f'_{self.sync_namespace}_softwareEvents.log.htsv', self.sync_collection, False), ],
             'output_files': [('mpci.times.npy', 'alf/mesoscope/FOV*', True),
-                             ('mpciStack.timeshift.npy', 'alf/mesoscope/FOV*', True), ]
+                             ('mpciStack.timeshift.npy', 'alf/mesoscope/FOV*', True),]
         }
         return signature
 
diff --git a/ibllib/pipes/tasks.py b/ibllib/pipes/tasks.py
index c55305e11..a409ed1ea 100644
--- a/ibllib/pipes/tasks.py
+++ b/ibllib/pipes/tasks.py
@@ -88,6 +88,7 @@
 from iblutil.util import Bunch
 import one.params
 from one.api import ONE
+from one.util import ensure_list
 from one import webclient
 
 _logger = logging.getLogger(__name__)
@@ -107,9 +108,10 @@ class Task(abc.ABC):
     time_elapsed_secs = None
     time_out_secs = 3600 * 2  # time-out after which a task is considered dead
     version = ibllib.__version__
-    signature = {'input_files': [], 'output_files': []}  # list of tuples (filename, collection, required_flag)
-    force = False  # whether or not to re-download missing input files on local server if not present
+    signature = {'input_files': [], 'output_files': []}  # list of tuples (filename, collection, required_flag[, register])
+    force = False  # whether to re-download missing input files on local server if not present
     job_size = 'small'  # either 'small' or 'large', defines whether task should be run as part of the large or small job services
+    env = None  # the environment name within which to run the task (NB: the env is not activated automatically!)
 
     def __init__(self, session_path, parents=None, taskid=None, one=None,
                  machine=None, clobber=True, location='server', **kwargs):
@@ -172,6 +174,13 @@ def run(self, **kwargs):
             -1: Errored
             -2: Didn't run as a lock was encountered
             -3: Incomplete
+
+        Notes
+        -----
+        - The `run_alyx_task` will update the Alyx Task status depending on both status and outputs
+          (i.e. the output of subclassed `_run` method):
+          Assuming a return value of 0... if Task.outputs is None, the status will be Empty;
+          if Task.outputs is a list (empty or otherwise), the status will be Complete.
         """
         # if task id of one properties are not available, local run only without alyx
         use_alyx = self.one is not None and self.taskid is not None
@@ -200,12 +209,13 @@ def run(self, **kwargs):
         start_time = time.time()
         try:
             setup = self.setUp(**kwargs)
+            self.outputs = self._input_files_to_register()
             _logger.info(f'Setup value is: {setup}')
             self.status = 0
             if not setup:
                 # case where outputs are present but don't have input files locally to rerun task
                 # label task as complete
-                _, self.outputs = self.assert_expected_outputs()
+                _, outputs = self.assert_expected_outputs()
             else:
                 # run task
                 if self.gpu >= 1:
@@ -217,8 +227,15 @@ def run(self, **kwargs):
                         _logger.removeHandler(ch)
                         ch.close()
                         return self.status
-                self.outputs = self._run(**kwargs)
+                outputs = self._run(**kwargs)
                 _logger.info(f'Job {self.__class__} complete')
+            if outputs is None:
+                # If run method returns None and no raw input files were registered, self.outputs
+                # should be None, meaning task will have an 'Empty' status. If run method returns
+                # a list, the status will be 'Complete' regardless of whether there are output files.
+                self.outputs = outputs if not self.outputs else self.outputs  # ensure None if no inputs registered
+            else:
+                self.outputs.extend(ensure_list(outputs))  # Add output files to list of inputs to register
         except Exception:
             _logger.error(traceback.format_exc())
             _logger.info(f'Job {self.__class__} errored')
@@ -262,6 +279,41 @@ def register_datasets(self, **kwargs):
         _ = self.register_images()
         return self.data_handler.uploadData(self.outputs, self.version, **kwargs)
 
+    def _input_files_to_register(self, assert_all_exist=False):
+        """
+        Return input datasets to be registered to Alyx.
+
+        These datasets are typically raw data files and are registered even if the task fails to complete.
+
+        Parameters
+        ----------
+        assert_all_exist
+            Raise AssertionError if not all required input datasets exist on disk.
+
+        Returns
+        -------
+        list of pathlib.Path
+            A list of input files to register.
+        """
+        try:
+            input_files = self.input_files
+        except AttributeError:
+            raise RuntimeError('Task.setUp must be run before calling this method.')
+        to_register, missing = [], []
+        for filename, collection, required, _ in filter(lambda f: len(f) > 3 and f[3], input_files):
+            filepath = self.session_path.joinpath(collection, filename)
+            if filepath.exists():
+                to_register.append(filepath)
+            elif required:
+                missing.append(filepath)
+        if any(missing):
+            missing_str = ', '.join(map(lambda x: x.relative_to(self.session_path).as_posix(), missing))
+            if assert_all_exist:
+                raise AssertionError(f'Missing required input files: {missing_str}')
+            else:
+                _logger.error(f'Missing required input files: {missing_str}')
+        return list(set(to_register) - set(missing))
+
     def register_images(self, **kwargs):
         """
         Registers images to alyx database
@@ -540,7 +592,8 @@ def make_graph(self, out_dir=None, show=True):
 
     def create_alyx_tasks(self, rerun__status__in=None, tasks_list=None):
         """
-        Instantiate the pipeline and create the tasks in Alyx, then create the jobs for the session
+        Instantiate the pipeline and create the tasks in Alyx, then create the jobs for the session.
+
         If the jobs already exist, they are left untouched. The re-run parameter will re-init the
         job by emptying the log and set the status to Waiting.
 
@@ -682,6 +735,24 @@ def name(self):
         return self.__class__.__name__
 
 
+def str2class(task_executable: str):
+    """
+    Convert task name to class.
+
+    Parameters
+    ----------
+    task_executable : str
+        A Task class name, e.g. 'ibllib.pipes.behavior_tasks.TrialRegisterRaw'.
+
+    Returns
+    -------
+    class
+        The imported class.
+    """
+    strmodule, strclass = task_executable.rsplit('.', 1)
+    return getattr(importlib.import_module(strmodule), strclass)
+
+
 def run_alyx_task(tdict=None, session_path=None, one=None, job_deck=None,
                   max_md5_size=None, machine=None, clobber=True, location='server', mode='log'):
     """
@@ -714,8 +785,8 @@ def run_alyx_task(tdict=None, session_path=None, one=None, job_deck=None,
 
     Returns
     -------
-    Task
-        The instantiated task object that was run.
+    dict
+        The updated task dict.
     list of pathlib.Path
         A list of registered datasets.
     """
@@ -736,9 +807,7 @@ def run_alyx_task(tdict=None, session_path=None, one=None, job_deck=None,
                 tdict = one.alyx.rest('tasks', 'partial_update', id=tdict['id'], data={'status': 'Held'})
             return tdict, registered_dsets
     # creates the job from the module name in the database
-    exec_name = tdict['executable']
-    strmodule, strclass = exec_name.rsplit('.', 1)
-    classe = getattr(importlib.import_module(strmodule), strclass)
+    classe = str2class(tdict['executable'])
     tkwargs = tdict.get('arguments') or {}  # if the db field is null it returns None
     task = classe(session_path, one=one, taskid=tdict['id'], machine=machine, clobber=clobber,
                   location=location, **tkwargs)
@@ -748,7 +817,7 @@ def run_alyx_task(tdict=None, session_path=None, one=None, job_deck=None,
     patch_data = {'time_elapsed_secs': task.time_elapsed_secs, 'log': task.log,
                   'version': task.version}
     # if there is no data to register, set status to Empty
-    if task.outputs is None:
+    if task.outputs is None:  # NB: an empty list is still considered Complete.
         patch_data['status'] = 'Empty'
     # otherwise register data and set (provisional) status to Complete
     else:
diff --git a/ibllib/tests/extractors/test_mesoscope.py b/ibllib/tests/extractors/test_mesoscope.py
new file mode 100644
index 000000000..b9447b630
--- /dev/null
+++ b/ibllib/tests/extractors/test_mesoscope.py
@@ -0,0 +1,64 @@
+"""Tests for ibllib.io.extractors.mesoscope module."""
+import unittest
+from itertools import repeat, chain
+
+import numpy as np
+
+from ibllib.io.extractors import mesoscope
+
+
+class TestMesoscopeSyncTimeline(unittest.TestCase):
+    """Tests for MesoscopeSyncTimeline extractor class."""
+    def setUp(self) -> None:
+        """Simulate for meta data for 9 FOVs at 3 different depths.
+
+        These simulated values match those from SP048/2024-02-05/001.
+        """
+        n_lines_flyback = 75
+        self.n_lines = 512
+        self.n_FOV = 9
+        n_depths = 3
+        assert self.n_FOV > n_depths and self.n_FOV % n_depths == 0
+        reps = int(self.n_FOV / n_depths)
+        start_depth = 60
+        delta_depth = 40
+        self.line_period = 4.158e-05
+
+        self.meta = {
+            'scanImageParams': {'hRoiManager': {'linePeriod': self.line_period, 'scanFrameRate': 13.6803}},
+            'FOV': []
+        }
+        nXnYnZ = [self.n_lines, self.n_lines, 1]
+        for i, slice_id in enumerate(chain.from_iterable(map(lambda x: list(repeat(x, reps)), range(n_depths)))):
+            offset = (i % n_depths) * (self.n_lines + n_lines_flyback) - ((i % n_depths) - 1)
+            offset = offset or 1  # start at 1 for MATLAB indexing
+            fov = {'slice_id': slice_id, 'Zs': start_depth + (delta_depth * slice_id),
+                   'nXnYnZ': nXnYnZ, 'lineIdx': list(range(offset, self.n_lines + offset))}
+            self.meta['FOV'].append(fov)
+
+    def test_get_timeshifts_multidepth(self):
+        """Test MescopeSyncTimeline.get_timeshifts method.
+
+        This tests output when given multiple FOVs at different depths. The tasks/mesoscope_tasks.py
+        module in iblscripts more thoroughly tests single-depth imaging with real data.
+        """
+        line_indices, fov_time_shifts, line_time_shifts = mesoscope.MesoscopeSyncTimeline.get_timeshifts(self.meta)
+        expected = [np.array(x['lineIdx']) for x in self.meta['FOV']]
+        self.assertTrue(np.all(x == y) for x, y in zip(expected, line_indices))
+        self.assertEqual(self.n_FOV, len(fov_time_shifts))
+        self.assertEqual(self.n_FOV, len(line_time_shifts))
+        self.assertTrue(all(len(x) == self.n_lines for x in line_time_shifts))
+
+        expected = self.line_period * np.arange(self.n_lines)
+        for i, line_shifts in enumerate(line_time_shifts):
+            with self.subTest(f'FOV == {i}'):
+                self.assertEqual(self.n_lines, len(line_shifts))
+                np.testing.assert_almost_equal(expected, line_shifts)
+
+        # NB: The following values are fixed for the setup parameters
+        expected = [0., 0.02436588, 0.04873176, 0.07309781, 0.09746369, 0.12182957, 0.14619562, 0.1705615, 0.19492738]
+        np.testing.assert_almost_equal(expected, fov_time_shifts)
+
+
+if __name__ == '__main__':
+    unittest.main()
diff --git a/ibllib/tests/test_mesoscope.py b/ibllib/tests/test_mesoscope.py
index 7ae3e5cd4..95afe8a4a 100644
--- a/ibllib/tests/test_mesoscope.py
+++ b/ibllib/tests/test_mesoscope.py
@@ -1,4 +1,4 @@
-"""Tests for ibllib.pipes.mesoscope_tasks"""
+"""Tests for ibllib.pipes.mesoscope_tasks."""
 import sys
 import unittest
 from unittest import mock
@@ -68,6 +68,7 @@ def test_meta(self):
         }
 
         meta = {
+            'nFrames': 2000,
             'scanImageParams': {'hStackManager': {'zs': 320},
                                 'hRoiManager': {'scanVolumeRate': 6.8}},
             'FOV': [{'topLeftDeg': [-1, 1.3], 'topRightDeg': [3, 1.3], 'bottomLeftDeg': [-1, 5.2],
@@ -256,10 +257,10 @@ class TestImagingMeta(unittest.TestCase):
     """Test raw imaging metadata versioning."""
     def test_patch_imaging_meta(self):
         """Test for ibllib.io.extractors.mesoscope.patch_imaging_meta function."""
-        meta = {'version': '0.1.0', 'FOV': [{'roiUuid': None}, {'roiUUID': None}]}
+        meta = {'version': '0.1.0', 'nFrames': 2000, 'FOV': [{'roiUuid': None}, {'roiUUID': None}]}
         new_meta = mesoscope.patch_imaging_meta(meta)
         self.assertEqual(set(chain(*map(dict.keys, new_meta['FOV']))), {'roiUUID'})
-        meta = {'FOV': [
+        meta = {'nFrames': 2000, 'FOV': [
             dict.fromkeys(['topLeftDeg', 'topRightDeg', 'bottomLeftDeg', 'bottomRightDeg']),
             dict.fromkeys(['topLeftMM', 'topRightMM', 'bottomLeftMM', 'bottomRightMM'])
         ]}
diff --git a/ibllib/tests/test_pipes.py b/ibllib/tests/test_pipes.py
index 14d0643af..9b1df5c1f 100644
--- a/ibllib/tests/test_pipes.py
+++ b/ibllib/tests/test_pipes.py
@@ -13,15 +13,15 @@
 from uuid import uuid4
 from datetime import datetime
 
+from one.webclient import AlyxClient
 from one.api import ONE, OneAlyx
 import iblutil.io.params as iopar
 from packaging.version import Version, InvalidVersion
 
 import ibllib.io.extractors.base
 import ibllib.tests.fixtures.utils as fu
-from ibllib.pipes import misc
+from ibllib.pipes import misc, local_server
 from ibllib.pipes.misc import sleepless
-from ibllib.pipes import local_server
 from ibllib.tests import TEST_DB
 import ibllib.pipes.scan_fix_passive_files as fix
 from ibllib.pipes.base_tasks import RegisterRawDataTask
@@ -41,6 +41,34 @@ def setUp(self):
         raw_behaviour_data.parent.joinpath('raw_session.flag').touch()
         fu.populate_task_settings(raw_behaviour_data, patch={'PYBPOD_PROTOCOL': 'ephys_optoChoiceWorld6.0.1'})
 
+    @mock.patch('ibllib.pipes.local_server.get_local_data_repository')
+    def test_task_queue(self, lab_repo_mock):
+        """Test ibllib.pipes.local_server.task_queue function."""
+        lab_repo_mock.return_value = 'foo_repo'
+        tasks = [
+            {'executable': 'ibllib.pipes.mesoscope_tasks.MesoscopePreprocess', 'priority': 80},
+            {'executable': 'ibllib.pipes.ephys_preprocessing.SpikeSorting', 'priority': SpikeSorting.priority},
+            {'executable': 'ibllib.pipes.base_tasks.RegisterRawDataTask', 'priority': RegisterRawDataTask.priority}
+        ]
+        alyx = mock.Mock(spec=AlyxClient)
+        alyx.rest.return_value = tasks
+        queue = local_server.task_queue(lab='foolab', alyx=alyx)
+        alyx.rest.assert_called()
+        self.assertEqual('Waiting', alyx.rest.call_args.kwargs.get('status'))
+        self.assertIn('foolab', alyx.rest.call_args.kwargs.get('django', ''))
+        self.assertIn('foo_repo', alyx.rest.call_args.kwargs.get('django', ''))
+        # Expect to return tasks in descending priority order, without mesoscope task (different env)
+        self.assertEqual([tasks[2], tasks[1]], queue)
+        # Expect only mesoscope task returned when relevant env passed
+        queue = local_server.task_queue(lab='foolab', alyx=alyx, env=('suite2p',))
+        self.assertEqual([tasks[0]], queue)
+        # Expect no tasks as mesoscope task is a large job
+        queue = local_server.task_queue(mode='small', lab='foolab', alyx=alyx, env=('suite2p',))
+        self.assertEqual([], queue)
+        # Expect only register task as it's the only small job
+        queue = local_server.task_queue(mode='small', lab='foolab', alyx=alyx)
+        self.assertEqual([tasks[2]], queue)
+
     @mock.patch('ibllib.pipes.local_server.IBLRegistrationClient')
     @mock.patch('ibllib.pipes.local_server.make_pipeline')
     def test_job_creator(self, pipeline_mock, _):
diff --git a/ibllib/tests/test_tasks.py b/ibllib/tests/test_tasks.py
index 602579922..482697b39 100644
--- a/ibllib/tests/test_tasks.py
+++ b/ibllib/tests/test_tasks.py
@@ -1,3 +1,4 @@
+"""Test ibllib.pipes.tasks module and Task class."""
 import shutil
 import tempfile
 import unittest
@@ -112,6 +113,7 @@ class TaskGpuLock(ibllib.pipes.tasks.Task):
     def setUp(self):
         self.make_lock_file()
         self.data_handler = self.get_data_handler()
+        self.input_files = []
         return True
 
     def _run(self, overwrite=False):
@@ -356,5 +358,51 @@ def test_get_device_collection(self):
         self.assertEqual('raw_ephys_data/probe00', collection)
 
 
+class TestTask(unittest.TestCase):
+    def setUp(self):
+        tmpdir = tempfile.TemporaryDirectory()
+        self.addCleanup(tmpdir.cleanup)
+        self.tmpdir = Path(tmpdir.name)
+        self.session_path = self.tmpdir.joinpath('subject', '1900-01-01', '001')
+        self.session_path.mkdir(parents=True)
+
+    def test_input_files_to_register(self):
+        """Test for Task._input_files_to_register method."""
+        task = Task00(self.session_path)
+        self.assertRaises(RuntimeError, task._input_files_to_register)
+        task.input_files = [('register.optional.ext', 'alf', False, True),
+                            ('register.optional_foo.ext', 'alf', False, True),
+                            ('register.required.ext', 'alf', True, True),
+                            ('ignore.required.ext', 'alf', True),
+                            ('ignore.optional.ext', 'alf', False)]
+        self.session_path.joinpath('alf').mkdir()
+        for f in task.input_files:
+            self.session_path.joinpath(f[1], f[0]).touch()
+        files = task._input_files_to_register(assert_all_exist=True)
+        expected = [self.session_path.joinpath('alf', 'register.required.ext'),
+                    self.session_path.joinpath('alf', 'register.optional.ext'),
+                    self.session_path.joinpath('alf', 'register.optional_foo.ext')]
+        self.assertCountEqual(files, expected)
+        expected[2].unlink()
+        with self.assertNoLogs(ibllib.pipes.tasks.__name__, level='ERROR'):
+            files = task._input_files_to_register(assert_all_exist=True)
+            self.assertCountEqual(files, expected[:2])
+        expected[0].unlink()
+        with self.assertLogs(ibllib.pipes.tasks.__name__, level='ERROR'):
+            files = task._input_files_to_register(assert_all_exist=False)
+        self.assertEqual(files, expected[1:2])
+        self.assertRaises(AssertionError, task._input_files_to_register, assert_all_exist=True)
+
+
+class TestMisc(unittest.TestCase):
+    """Tests for misc functions in ibllib.pipes.tasks module."""
+
+    def test_str2class(self):
+        """Test ibllib.pipes.tasks.str2class function."""
+        task_str = 'ibllib.pipes.base_tasks.ExperimentDescriptionRegisterRaw'
+        self.assertIs(ibllib.pipes.tasks.str2class(task_str), ExperimentDescriptionRegisterRaw)
+        self.assertRaises(AttributeError, ibllib.pipes.tasks.str2class, 'ibllib.pipes.base_tasks.Foo')
+
+
 if __name__ == '__main__':
     unittest.main(exit=False, verbosity=2)