diff --git a/docker/build.sh b/docker/build.sh
index d0b1f46bfe..4afe95fe2d 100755
--- a/docker/build.sh
+++ b/docker/build.sh
@@ -27,6 +27,7 @@ IMAGES=(
   gcr.io/clusterfuzz-images/oss-fuzz/worker
   gcr.io/clusterfuzz-images/ci
   gcr.io/clusterfuzz-images/utask-main-scheduler
+  gcr.io/clusterfuzz-images/tworker
   gcr.io/clusterfuzz-images/fuchsia
 )
 
diff --git a/docker/tworker/Dockerfile b/docker/tworker/Dockerfile
new file mode 100644
index 0000000000..0c9c008cf3
--- /dev/null
+++ b/docker/tworker/Dockerfile
@@ -0,0 +1,17 @@
+# Copyright 2024 Google LLC
+#
+# 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.
+FROM gcr.io/clusterfuzz-images/base
+
+# Worker that only reads from queues, preprocesses and postprocesses.
+ENV TWORKER=1
diff --git a/src/clusterfuzz/_internal/base/tasks/__init__.py b/src/clusterfuzz/_internal/base/tasks/__init__.py
index bc0a269c7c..378ba94c96 100644
--- a/src/clusterfuzz/_internal/base/tasks/__init__.py
+++ b/src/clusterfuzz/_internal/base/tasks/__init__.py
@@ -83,6 +83,7 @@
 
 POSTPROCESS_QUEUE = 'postprocess'
 UTASK_MAINS_QUEUE = 'utask_main'
+PREPROCESS_QUEUE = 'preprocess'
 
 # See https://github.com/google/clusterfuzz/issues/3347 for usage
 SUBQUEUE_IDENTIFIER = ':'
@@ -281,8 +282,7 @@ def is_done_collecting_messages():
 def get_postprocess_task():
   """Gets a postprocess task if one exists."""
   # This should only be run on non-preemptible bots.
-  if not (task_utils.is_remotely_executing_utasks() or
-          task_utils.get_opted_in_tasks()):
+  if not task_utils.is_remotely_executing_utasks():
     return None
   # Postprocess is platform-agnostic, so we run all such tasks on our
   # most generic and plentiful bots only. In other words, we avoid
@@ -304,9 +304,29 @@ def allow_all_tasks():
   return not environment.get_value('PREEMPTIBLE')
 
 
+def get_preprocess_task():
+  pubsub_puller = PubSubPuller(PREPROCESS_QUEUE)
+  messages = pubsub_puller.get_messages(max_messages=1)
+  if not messages:
+    return None
+  task = get_task_from_message(messages[0])
+  if task:
+    logs.info('Pulled from preprocess queue.')
+  return task
+
+
+def tworker_get_task():
+  assert environment.is_tworker()
+  task = get_postprocess_task()
+  if task:
+    return task
+
+  return get_preprocess_task()
+
+
 def get_task():
-  """Returns an ordinary (non-postprocess, non-utask_main) task that is pulled
-  from a ClusterFuzz task queue."""
+  """Returns an ordinary (non-utask_main) task that is pulled from a ClusterFuzz
+  task queue."""
   task = get_command_override()
   if task:
     return task
@@ -319,6 +339,7 @@ def get_task():
     task = get_postprocess_task()
     if task:
       return task
+
     # Check the high-end jobs queue for bots with multiplier greater than 1.
     thread_multiplier = environment.get_value('THREAD_MULTIPLIER')
     if thread_multiplier and thread_multiplier > 1:
@@ -368,8 +389,7 @@ def __init__(self,
                eta=None,
                is_command_override=False,
                high_end=False,
-               extra_info=None,
-               is_from_queue=False):
+               extra_info=None):
     self.command = command
     self.argument = argument
     self.job = job
@@ -378,16 +398,6 @@ def __init__(self,
     self.high_end = high_end
     self.extra_info = extra_info
 
-    # is_from_queue is a temporary hack to keep track of which fuzz tasks came
-    # from the queue. Previously all fuzz tasks were picked by the bot when
-    # there was nothing on the queue. With the rearchitecture, we want fuzz
-    # tasks that were put on the queue by the schedule_fuzz cron job to be
-    # executed on batch. is_from_queue is used to do this.
-    # TODO(b/378684001): This code is very ugly, get rid of it when no more
-    # fuzz tasks are executed on the bots themselves (i.e. when the rearch
-    # is complete).
-    self.is_from_queue = is_from_queue
-
   def __repr__(self):
     return f'Task: {self.command} {self.argument} {self.job}'
 
@@ -428,13 +438,11 @@ def lease(self):
 class PubSubTask(Task):
   """A Pub/Sub task."""
 
-  def __init__(self, pubsub_message, is_from_queue=False):
+  def __init__(self, pubsub_message):
     self._pubsub_message = pubsub_message
     super().__init__(
-        self.attribute('command'),
-        self.attribute('argument'),
-        self.attribute('job'),
-        is_from_queue=is_from_queue)
+        self.attribute('command'), self.attribute('argument'),
+        self.attribute('job'))
 
     self.extra_info = {
         key: value
@@ -540,7 +548,7 @@ def initialize_task(message) -> PubSubTask:
   """Creates a task from |messages|."""
 
   if message.attributes.get('eventType') != 'OBJECT_FINALIZE':
-    return PubSubTask(message, is_from_queue=True)
+    return PubSubTask(message)
 
   # Handle postprocess task.
   # The GCS API for pub/sub notifications uses the data field unlike
@@ -549,7 +557,7 @@ def initialize_task(message) -> PubSubTask:
   name = data['name']
   bucket = data['bucket']
   output_url_argument = storage.get_cloud_storage_file_path(bucket, name)
-  return PostprocessPubSubTask(output_url_argument, message, is_from_queue=True)
+  return PostprocessPubSubTask(output_url_argument, message)
 
 
 class PostprocessPubSubTask(PubSubTask):
@@ -558,21 +566,14 @@ class PostprocessPubSubTask(PubSubTask):
   def __init__(self,
                output_url_argument,
                pubsub_message,
-               is_command_override=False,
-               is_from_queue=False):
+               is_command_override=False):
     command = 'postprocess'
     job_type = 'none'
     eta = None
     high_end = False
     grandparent_class = super(PubSubTask, self)
-    grandparent_class.__init__(
-        command,
-        output_url_argument,
-        job_type,
-        eta,
-        is_command_override,
-        high_end,
-        is_from_queue=is_from_queue)
+    grandparent_class.__init__(command, output_url_argument, job_type, eta,
+                               is_command_override, high_end)
     self._pubsub_message = pubsub_message
 
 
diff --git a/src/clusterfuzz/_internal/base/tasks/task_utils.py b/src/clusterfuzz/_internal/base/tasks/task_utils.py
index 9248dad52d..bc5b36f4a8 100644
--- a/src/clusterfuzz/_internal/base/tasks/task_utils.py
+++ b/src/clusterfuzz/_internal/base/tasks/task_utils.py
@@ -15,7 +15,6 @@
 any other module in tasks to prevent circular imports and issues with
 appengine."""
 
-from clusterfuzz._internal.config import local_config
 from clusterfuzz._internal.system import environment
 
 
@@ -26,25 +25,12 @@ def get_command_from_module(full_module_name: str) -> str:
   return module_name[:-len('_task')]
 
 
-def is_remotely_executing_utasks(task=None) -> bool:
+def is_remotely_executing_utasks() -> bool:
   """Returns True if the utask_main portions of utasks are being remotely
   executed on Google cloud batch."""
-  if bool(environment.is_production() and
-          environment.get_value('REMOTE_UTASK_EXECUTION')):
-    return True
-  if task is None:
-    return False
-  return bool(is_task_opted_into_uworker_execution(task))
-
-
-def get_opted_in_tasks():
-  return local_config.ProjectConfig().get('uworker_tasks', [])
-
-
-def is_task_opted_into_uworker_execution(task: str) -> bool:
-  # TODO(metzman): Remove this after OSS-Fuzz and Chrome are at parity.
-  uworker_tasks = get_opted_in_tasks()
-  return task in uworker_tasks
+  # TODO(metzman): REMOTE_UTASK_EXECUTION should be a config not an env var.
+  return (environment.is_production() and
+          environment.get_value('REMOTE_UTASK_EXECUTION'))
 
 
 class UworkerMsgParseError(RuntimeError):
diff --git a/src/clusterfuzz/_internal/bot/tasks/commands.py b/src/clusterfuzz/_internal/bot/tasks/commands.py
index 01d69c5c86..8c887dec1e 100644
--- a/src/clusterfuzz/_internal/bot/tasks/commands.py
+++ b/src/clusterfuzz/_internal/bot/tasks/commands.py
@@ -190,11 +190,25 @@ def start_web_server_if_needed():
     logs.error('Failed to start web server, skipping.')
 
 
+def get_command_object(task_name):
+  """Returns the command object that execute can be called on."""
+  task = COMMAND_MAP.get(task_name)
+  if not environment.is_tworker():
+    return task
+
+  if isinstance(task, task_types.TrustedTask):
+    # We don't need to execute this remotely.
+    return task
+
+  # Force remote execution.
+  return task_types.UTask(task_name)
+
+
 def run_command(task_name, task_argument, job_name, uworker_env):
   """Runs the command."""
-  task = COMMAND_MAP.get(task_name)
+  task = get_command_object(task_name)
   if not task:
-    logs.error("Unknown command '%s'" % task_name)
+    logs.error(f'Unknown command "{task_name}"')
     return None
 
   # If applicable, ensure this is the only instance of the task running.
@@ -253,10 +267,8 @@ def process_command(task):
     logs.error('Empty task received.')
     return None
 
-  # TODO(b/378684001): Remove is_from_queue kludge.
   return process_command_impl(task.command, task.argument, task.job,
-                              task.high_end, task.is_command_override,
-                              task.is_from_queue)
+                              task.high_end, task.is_command_override)
 
 
 def _get_task_id(task_name, task_argument, job_name):
@@ -267,13 +279,12 @@ def _get_task_id(task_name, task_argument, job_name):
 # TODO(mbarbella): Rewrite this function to avoid nesting issues.
 @set_task_payload
 def process_command_impl(task_name, task_argument, job_name, high_end,
-                         is_command_override, is_from_queue):
+                         is_command_override):
   """Implementation of process_command."""
   uworker_env = None
   environment.set_value('TASK_NAME', task_name)
   environment.set_value('TASK_ARGUMENT', task_argument)
   environment.set_value('JOB_NAME', job_name)
-  environment.set_value('IS_FROM_QUEUE', is_from_queue)
   if task_name in {'uworker_main', 'postprocess'}:
     # We want the id of the task we are processing, not "uworker_main", or
     # "postprocess".
@@ -455,5 +466,3 @@ def process_command_impl(task_name, task_argument, job_name, high_end,
     cleanup_task_state()
     if 'CF_TASK_ID' in os.environ:
       del os.environ['CF_TASK_ID']
-    if 'IS_FROM_QUEUE' in os.environ:
-      del os.environ['IS_FROM_QUEUE']
diff --git a/src/clusterfuzz/_internal/bot/tasks/task_types.py b/src/clusterfuzz/_internal/bot/tasks/task_types.py
index 648baf9c23..a338ef0ac3 100644
--- a/src/clusterfuzz/_internal/bot/tasks/task_types.py
+++ b/src/clusterfuzz/_internal/bot/tasks/task_types.py
@@ -46,6 +46,7 @@ class TrustedTask(BaseTask):
   def execute(self, task_argument, job_type, uworker_env):
     # Simple tasks can just use the environment they don't need the uworker env.
     del uworker_env
+    assert not environment.is_tworker()
     self.module.execute_task(task_argument, job_type)
 
 
@@ -58,6 +59,8 @@ def execute(self, task_argument, job_type, uworker_env):
     raise NotImplementedError('Child class must implement.')
 
   def execute_locally(self, task_argument, job_type, uworker_env):
+    """Executes the utask locally (on this machine, not on batch)."""
+    assert not environment.is_tworker()
     uworker_input = utasks.tworker_preprocess_no_io(self.module, task_argument,
                                                     job_type, uworker_env)
     if uworker_input is None:
@@ -119,7 +122,7 @@ class UTask(BaseUTask):
 
   @staticmethod
   def is_execution_remote(command=None):
-    return task_utils.is_remotely_executing_utasks(command)
+    return task_utils.is_remotely_executing_utasks()
 
   def execute(self, task_argument, job_type, uworker_env):
     """Executes a utask."""
@@ -156,19 +159,6 @@ def preprocess(self, task_argument, job_type, uworker_env):
     return download_url
 
 
-# TODO(b/378684001): Remove this, it's needed for testing but is otherwise a bad
-# design.
-class UTaskMostlyLocalExecutor(UTask):
-
-  @staticmethod
-  def is_execution_remote(command=None):
-    del command
-    if environment.get_value('IS_FROM_QUEUE'):
-      logs.info('IS FROM QUEUE')
-      return True
-    return False
-
-
 class PostprocessTask(BaseTask):
   """Represents postprocessing of an untrusted task."""
 
@@ -211,7 +201,7 @@ def execute(self, task_argument, job_type, uworker_env):
     'analyze': UTask,
     'blame': TrustedTask,
     'corpus_pruning': UTask,
-    'fuzz': UTaskMostlyLocalExecutor,
+    'fuzz': UTaskLocalExecutor,
     'impact': TrustedTask,
     'minimize': UTask,
     'progression': UTask,
diff --git a/src/clusterfuzz/_internal/cron/schedule_fuzz.py b/src/clusterfuzz/_internal/cron/schedule_fuzz.py
index d5116e197e..6d8269357a 100644
--- a/src/clusterfuzz/_internal/cron/schedule_fuzz.py
+++ b/src/clusterfuzz/_internal/cron/schedule_fuzz.py
@@ -20,7 +20,6 @@
 
 from googleapiclient import discovery
 
-from clusterfuzz._internal.base import concurrency
 from clusterfuzz._internal.base import tasks
 from clusterfuzz._internal.base import utils
 from clusterfuzz._internal.config import local_config
@@ -167,14 +166,12 @@ def get_fuzz_tasks(self) -> Dict[str, tasks.Task]:
 
     choices = random.choices(
         fuzz_task_candidates, weights=weights, k=num_instances)
-    queues_to_tasks = collections.defaultdict(list)
-    for fuzz_task_candidate in choices:
-      queue_tasks = queues_to_tasks[fuzz_task_candidate.queue]
-
-      task = tasks.Task('fuzz', fuzz_task_candidate.fuzzer,
-                        fuzz_task_candidate.job)
-      queue_tasks.append(task)
-    return queues_to_tasks
+    fuzz_tasks = [
+        tasks.Task('fuzz', fuzz_task_candidate.fuzzer, fuzz_task_candidate.job)
+        for fuzz_task_candidate in choices
+    ]
+    # TODO(metzman): Remove the queue stuff if it's uneeded for Chrome.
+    return fuzz_tasks
 
 
 def get_fuzz_tasks(available_cpus: int) -> [tasks.Task]:
@@ -210,10 +207,8 @@ def schedule_fuzz_tasks() -> bool:
     logs.error('No fuzz tasks found to schedule.')
     return False
 
-  # TODO(b/378684001): Change this to using one queue when oss-fuzz's untrusted
-  # worker model is deleted.
-  with concurrency.make_pool() as pool:
-    list(pool.map(bulk_add, fuzz_tasks.items()))
+  logs.info(f'Adding {fuzz_tasks} to preprocess queue.')
+  tasks.bulk_add_tasks(fuzz_tasks, queue=tasks.PREPROCESS_QUEUE, eta_now=True)
   logs.info(f'Scheduled {len(fuzz_tasks)} fuzz tasks.')
 
   end = time.time()
@@ -222,11 +217,5 @@ def schedule_fuzz_tasks() -> bool:
   return True
 
 
-def bulk_add(queue_and_tasks):
-  queue, task_list = queue_and_tasks
-  logs.info(f'Adding {task_list} to {queue}.')
-  tasks.bulk_add_tasks(task_list, queue=queue, eta_now=True)
-
-
 def main():
   return schedule_fuzz_tasks()
diff --git a/src/clusterfuzz/_internal/system/environment.py b/src/clusterfuzz/_internal/system/environment.py
index e889749f20..abaae14a2e 100644
--- a/src/clusterfuzz/_internal/system/environment.py
+++ b/src/clusterfuzz/_internal/system/environment.py
@@ -1177,3 +1177,7 @@ def can_testcase_run_on_platform(testcase_platform_id, current_platform_id):
                                                      current_platform_id)
 
   return False
+
+
+def is_tworker():
+  return get_value('TWORKER', False)
diff --git a/src/clusterfuzz/_internal/tests/appengine/common/tasks_test.py b/src/clusterfuzz/_internal/tests/appengine/common/tasks_test.py
index 6769fb75b6..2a99dc9dfb 100644
--- a/src/clusterfuzz/_internal/tests/appengine/common/tasks_test.py
+++ b/src/clusterfuzz/_internal/tests/appengine/common/tasks_test.py
@@ -52,13 +52,11 @@ def setUp(self):
         'clusterfuzz._internal.base.persistent_cache.get_value',
         'clusterfuzz._internal.base.persistent_cache.set_value',
         'clusterfuzz._internal.base.utils.utcnow',
-        'clusterfuzz._internal.base.tasks.task_utils.get_opted_in_tasks',
         'time.sleep',
     ])
 
     self.mock.get_value.return_value = None
     self.mock.sleep.return_value = None
-    self.mock.get_opted_in_tasks.return_value = False
     data_types.Job(name='job').put()
 
     client = pubsub.PubSubClient()
diff --git a/src/clusterfuzz/_internal/tests/appengine/handlers/cron/schedule_fuzz_test.py b/src/clusterfuzz/_internal/tests/appengine/handlers/cron/schedule_fuzz_test.py
index ae74ec4ddd..a849875c0b 100644
--- a/src/clusterfuzz/_internal/tests/appengine/handlers/cron/schedule_fuzz_test.py
+++ b/src/clusterfuzz/_internal/tests/appengine/handlers/cron/schedule_fuzz_test.py
@@ -69,16 +69,12 @@ def test_get_fuzz_tasks(self):
 
     num_cpus = 10
     scheduler = schedule_fuzz.OssfuzzFuzzTaskScheduler(num_cpus)
-    results = scheduler.get_fuzz_tasks()
+    tasks = scheduler.get_fuzz_tasks()
     comparable_results = []
-    for tasks in results.values():
-      comparable_tasks = []
-      for task in tasks:
-        comparable_tasks.append((task.command, task.argument, task.job))
-      comparable_results.append(comparable_tasks)
-
-    expected_results = [[('fuzz', 'libFuzzer', 'myjob')] * 5]
-    self.assertListEqual(list(results.keys()), ['jobs-linux'])
+    for task in tasks:
+      comparable_results.append((task.command, task.argument, task.job))
+
+    expected_results = [('fuzz', 'libFuzzer', 'myjob')] * 5
     self.assertListEqual(comparable_results, expected_results)
 
 
diff --git a/src/clusterfuzz/_internal/tests/core/base/tasks/task_utils_test.py b/src/clusterfuzz/_internal/tests/core/base/tasks/task_utils_test.py
index 8c914203b9..31a37c8efd 100644
--- a/src/clusterfuzz/_internal/tests/core/base/tasks/task_utils_test.py
+++ b/src/clusterfuzz/_internal/tests/core/base/tasks/task_utils_test.py
@@ -12,12 +12,10 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 """Tests for task_utils."""
-import os
 import unittest
 
 from clusterfuzz._internal.base.tasks import task_utils
 from clusterfuzz._internal.bot.tasks import commands
-from clusterfuzz._internal.tests.test_libs import helpers
 
 
 class GetCommandFromModuleTest(unittest.TestCase):
@@ -35,19 +33,3 @@ def test_get_command_from_module(self):
       task_utils.get_command_from_module('postprocess')
     with self.assertRaises(ValueError):
       task_utils.get_command_from_module('uworker_main')
-
-
-class IsTaskOptedIntoUworkerExecution(unittest.TestCase):
-  """Tests that is_task_opted_into_uworker_execution only returns True for the
-  tasks we are testing in oss-fuzz."""
-
-  def setUp(self):
-    helpers.patch_environ(self)
-
-  def test_opt_in(self):
-    os.environ['JOB_NAME'] = 'libfuzzer_asan_skia'
-    self.assertTrue(task_utils.is_task_opted_into_uworker_execution('analyze'))
-
-  def test_no_opt_in(self):
-    os.environ['JOB_NAME'] = 'libfuzzer_asan_skia'
-    self.assertFalse(task_utils.is_task_opted_into_uworker_execution('fuzz'))
diff --git a/src/python/bot/startup/run_bot.py b/src/python/bot/startup/run_bot.py
index 886ee44120..8c674fba2c 100644
--- a/src/python/bot/startup/run_bot.py
+++ b/src/python/bot/startup/run_bot.py
@@ -29,7 +29,7 @@
 
 from clusterfuzz._internal.base import dates
 from clusterfuzz._internal.base import errors
-from clusterfuzz._internal.base import tasks as taskslib
+from clusterfuzz._internal.base import tasks
 from clusterfuzz._internal.base import untrusted
 from clusterfuzz._internal.base import utils
 from clusterfuzz._internal.base.tasks import task_utils
@@ -89,7 +89,7 @@ def schedule_utask_mains():
   from clusterfuzz._internal.google_cloud_utils import batch
 
   logs.info('Attempting to combine batch tasks.')
-  utask_mains = taskslib.get_utask_mains()
+  utask_mains = tasks.get_utask_mains()
   if not utask_mains:
     logs.info('No utask mains.')
     return
@@ -135,7 +135,11 @@ def task_loop():
         schedule_utask_mains()
         continue
 
-      task = taskslib.get_task()
+      if environment.is_tworker():
+        task = tasks.tworker_get_task()
+      else:
+        task = tasks.get_task()
+
       if not task:
         continue