diff --git a/src/dvsim/flow/base.py b/src/dvsim/flow/base.py
index a84ae674..ff126f08 100644
--- a/src/dvsim/flow/base.py
+++ b/src/dvsim/flow/base.py
@@ -422,7 +422,7 @@ def deploy_objects(self) -> Mapping[str, CompletedJobStatus]:
                 json.dumps(
                     # Sort on full name to ensure consistent ordering
                     sorted(
-                        [d.model_dump() for d in deploy],
+                        [d.dump() for d in deploy],
                         key=lambda d: d["full_name"],
                     ),
                     indent=2,
@@ -445,16 +445,19 @@ def _gen_results(self, results: Mapping[str, CompletedJobStatus]) -> str:
         prints the full list of failures for debug / triage to the final
         report, which is in markdown format.
 
-        Results:
-            dictionary mapping deployed item names to job status.
+        Args:
+            results: dictionary mapping deployed item names to completed job status.
+
+        Returns:
+            Results as a formatted string
 
         """
 
     def gen_results(self, results: Mapping[str, CompletedJobStatus]) -> None:
-        """Public facing API for _gen_results().
+        """Generate flow results.
 
         Args:
-            results: dictionary mapping deployed item names to job status.
+            results: dictionary mapping deployed item names to completed job status.
 
         """
         for item in self.cfgs:
diff --git a/src/dvsim/job/deploy.py b/src/dvsim/job/deploy.py
index 53944224..511f157a 100644
--- a/src/dvsim/job/deploy.py
+++ b/src/dvsim/job/deploy.py
@@ -11,6 +11,8 @@
 from pathlib import Path
 from typing import TYPE_CHECKING, ClassVar
 
+from pydantic import BaseModel
+from pydantic.config import ConfigDict
 from tabulate import tabulate
 
 from dvsim.job.time import JobTime
@@ -26,6 +28,21 @@
 
 if TYPE_CHECKING:
     from dvsim.flow.sim import SimCfg
+    from dvsim.modes import BuildMode
+
+
+class WorkspaceConfig(BaseModel):
+    """Workspace configuration."""
+
+    model_config = ConfigDict(frozen=True, extra="forbid")
+
+    project: str
+    timestamp: str
+
+    project_root: Path
+    scratch_root: Path
+    scratch_path: Path
+
 
 __all__ = (
     "CompileSim",
@@ -101,6 +118,14 @@ def __init__(self, sim_cfg: "SimCfg") -> None:
         # Job's wall clock time (a.k.a CPU time, or runtime).
         self.job_runtime = JobTime()
 
+        self.workspace_cfg = WorkspaceConfig(
+            project=sim_cfg.name,
+            project_root=sim_cfg.proj_root,
+            scratch_root=Path(sim_cfg.scratch_root),
+            scratch_path=Path(sim_cfg.scratch_path),
+            timestamp=sim_cfg.args.timestamp,
+        )
+
     def _define_attrs(self) -> None:
         """Define the attributes this instance needs to have.
 
@@ -293,7 +318,7 @@ def pre_launch(self, launcher: Launcher) -> None:
         This is invoked by launcher::_pre_launch().
         """
 
-    def post_finish(self, status) -> None:
+    def post_finish(self, status: str) -> None:
         """Perform additional post-finish activities (callback).
 
         This is invoked by launcher::_post_finish().
@@ -328,12 +353,9 @@ def extract_info_from_log(self, job_runtime_secs: int, log_text: list) -> None:
             log.warning(f"{self.full_name}: {e} Using dvsim-maintained job_runtime instead.")
             self.job_runtime.set(job_runtime_secs, "s")
 
-    def model_dump(self) -> Mapping:
+    def dump(self) -> Mapping:
         """Dump the deployment object to mapping object.
 
-        This method matches the interface provided by pydantic models to dump a
-        subset of the class attributes
-
         Returns:
             Representation of a deployment object as a dict.
 
@@ -371,6 +393,20 @@ def __init__(self, build_mode, sim_cfg) -> None:
                 self.build_timeout_mins,
             )
 
+    @staticmethod
+    def new(build_mode_obj: "BuildMode", sim_cfg: "SimCfg") -> "CompileSim":
+        """Create a new CompileSim object.
+
+        Args:
+            build_mode_obj: build mode instance
+            sim_cfg: Simulation config object
+
+        Returns:
+            new CompileSim object.
+
+        """
+        return CompileSim(build_mode=build_mode_obj, sim_cfg=sim_cfg)
+
     def _define_attrs(self) -> None:
         """Define attributes."""
         super()._define_attrs()
@@ -711,6 +747,10 @@ def __init__(self, run_items, sim_cfg) -> None:
                 else:
                     self.cov_db_dirs.append(run.cov_db_dir)
 
+        # Sort the cov_db_dir except for the first directory
+        if len(self.cov_db_dirs) > 1:
+            self.cov_db_dirs = [self.cov_db_dirs[0], *sorted(self.cov_db_dirs[1:])]
+
         # Early lookup the cov_merge_db_dir, which is a mandatory misc
         # attribute anyway. We need it to compute additional cov db dirs.
         self.cov_merge_db_dir = subst_wildcards("{cov_merge_db_dir}", sim_cfg.__dict__)
diff --git a/src/dvsim/launcher/base.py b/src/dvsim/launcher/base.py
index f5bc73c7..b852442f 100644
--- a/src/dvsim/launcher/base.py
+++ b/src/dvsim/launcher/base.py
@@ -19,7 +19,7 @@
 from dvsim.utils import clean_odirs, mk_symlink, rm_path
 
 if TYPE_CHECKING:
-    from dvsim.job.deploy import Deploy
+    from dvsim.job.deploy import Deploy, WorkspaceConfig
 
 
 class LauncherError(Exception):
@@ -67,7 +67,7 @@ class Launcher(ABC):
     poll_freq = 1
 
     # Points to the python virtual env area.
-    pyvenv = None
+    pyvenv: Path | None = None
 
     # If a history of previous invocations is to be maintained, then keep no
     # more than this many directories.
@@ -97,18 +97,18 @@ def __init__(self, deploy: "Deploy") -> None:
             deploy: deployment object that will be launched.
 
         """
-        cfg = deploy.sim_cfg
+        workspace_cfg = deploy.workspace_cfg
 
         # One-time preparation of the workspace.
         if not Launcher.workspace_prepared:
-            # TODO: CLI args should be processed far earlier than this
-            self.prepare_workspace(cfg.project, cfg.proj_root, cfg.args)
+            self.prepare_workspace(workspace_cfg)
             Launcher.workspace_prepared = True
 
         # One-time preparation of the workspace, specific to the cfg.
-        if cfg not in Launcher.workspace_prepared_for_cfg:
-            self.prepare_workspace_for_cfg(cfg)
-            Launcher.workspace_prepared_for_cfg.add(cfg)
+        project = workspace_cfg.project
+        if project not in Launcher.workspace_prepared_for_cfg:
+            self.prepare_workspace_for_cfg(workspace_cfg)
+            Launcher.workspace_prepared_for_cfg.add(project)
 
         # Store the deploy object handle.
         self.deploy = deploy
@@ -155,34 +155,40 @@ def set_pyvenv(project: str) -> None:
         # The code below allows each launcher variant to set its own virtualenv
         # because the loading / activating mechanism could be different between
         # them.
-        Launcher.pyvenv = os.environ.get(
-            f"{project.upper()}_PYVENV_{Launcher.variant.upper()}",
-        )
+        common_venv = f"{project.upper()}_PYVENV"
+        variant = Launcher.variant.upper()
+
+        venv_path = os.environ.get(f"{common_venv}_{variant}")
+
+        if not venv_path:
+            venv_path = os.environ.get(common_venv)
 
-        if not Launcher.pyvenv:
-            Launcher.pyvenv = os.environ.get(f"{project.upper()}_PYVENV")
+        if venv_path:
+            Launcher.pyvenv = Path(venv_path)
 
     @staticmethod
     @abstractmethod
-    def prepare_workspace(project: str, repo_top: str, args: Mapping) -> None:
+    def prepare_workspace(cfg: "WorkspaceConfig") -> None:
         """Prepare the workspace based on the chosen launcher's needs.
 
         This is done once for the entire duration for the flow run.
 
         Args:
-            project: the name of the project.
-            repo_top: the path to the repository.
-            args: command line args passed to dvsim.
+            cfg: workspace configuration
 
         """
 
     @staticmethod
     @abstractmethod
-    def prepare_workspace_for_cfg(cfg: Mapping) -> None:
+    def prepare_workspace_for_cfg(cfg: "WorkspaceConfig") -> None:
         """Prepare the workspace for a cfg.
 
         This is invoked once for each cfg.
         'cfg' is the flow configuration object.
+
+        Args:
+            cfg: workspace configuration
+
         """
 
     def __str__(self) -> str:
@@ -250,6 +256,10 @@ def poll(self) -> str | None:
         """Poll the launched job for completion.
 
         Invokes _check_status() and _post_finish() when the job completes.
+
+        Returns:
+            status of the job or None
+
         """
 
     @abstractmethod
diff --git a/src/dvsim/launcher/fake.py b/src/dvsim/launcher/fake.py
index 8bd38446..82e1da96 100644
--- a/src/dvsim/launcher/fake.py
+++ b/src/dvsim/launcher/fake.py
@@ -4,14 +4,14 @@
 
 """Fake Launcher that returns random results."""
 
-from collections.abc import Mapping
 from random import choice, random
 from typing import TYPE_CHECKING
 
 from dvsim.launcher.base import ErrorMessage, Launcher
 
 if TYPE_CHECKING:
-    from dvsim.job.deploy import CovReport, Deploy, RunTest
+    from dvsim.job.deploy import CovReport, Deploy, RunTest, WorkspaceConfig
+
 
 __all__ = ("FakeLauncher",)
 
@@ -75,22 +75,23 @@ def kill(self) -> None:
         )
 
     @staticmethod
-    def prepare_workspace(project: str, repo_top: str, args: Mapping) -> None:
+    def prepare_workspace(cfg: "WorkspaceConfig") -> None:
         """Prepare the workspace based on the chosen launcher's needs.
 
         This is done once for the entire duration for the flow run.
 
         Args:
-            project: the name of the project.
-            repo_top: the path to the repository.
-            args: command line args passed to dvsim.
+            cfg: workspace configuration
 
         """
 
     @staticmethod
-    def prepare_workspace_for_cfg(cfg: Mapping) -> None:
+    def prepare_workspace_for_cfg(cfg: "WorkspaceConfig") -> None:
         """Prepare the workspace for a cfg.
 
         This is invoked once for each cfg.
-        'cfg' is the flow configuration object.
+
+        Args:
+            cfg: workspace configuration
+
         """
diff --git a/src/dvsim/launcher/local.py b/src/dvsim/launcher/local.py
index 8ea688ce..bc703f4d 100644
--- a/src/dvsim/launcher/local.py
+++ b/src/dvsim/launcher/local.py
@@ -8,14 +8,13 @@
 import os
 import shlex
 import subprocess
-from collections.abc import Mapping
 from pathlib import Path
 from typing import TYPE_CHECKING
 
 from dvsim.launcher.base import ErrorMessage, Launcher, LauncherBusyError, LauncherError
 
 if TYPE_CHECKING:
-    from dvsim.job.deploy import Deploy
+    from dvsim.job.deploy import Deploy, WorkspaceConfig
 
 
 class LocalLauncher(Launcher):
@@ -184,22 +183,23 @@ def _close_job_log_file(self) -> None:
             self._log_file.close()
 
     @staticmethod
-    def prepare_workspace(project: str, repo_top: str, args: Mapping) -> None:
+    def prepare_workspace(cfg: "WorkspaceConfig") -> None:
         """Prepare the workspace based on the chosen launcher's needs.
 
         This is done once for the entire duration for the flow run.
 
         Args:
-            project: the name of the project.
-            repo_top: the path to the repository.
-            args: command line args passed to dvsim.
+            cfg: workspace configuration
 
         """
 
     @staticmethod
-    def prepare_workspace_for_cfg(cfg: Mapping) -> None:
+    def prepare_workspace_for_cfg(cfg: "WorkspaceConfig") -> None:
         """Prepare the workspace for a cfg.
 
         This is invoked once for each cfg.
-        'cfg' is the flow configuration object.
+
+        Args:
+            cfg: workspace configuration
+
         """
diff --git a/src/dvsim/launcher/lsf.py b/src/dvsim/launcher/lsf.py
index e2933c7a..e8d5277c 100644
--- a/src/dvsim/launcher/lsf.py
+++ b/src/dvsim/launcher/lsf.py
@@ -7,19 +7,27 @@
 import subprocess
 import tarfile
 from pathlib import Path
+from typing import TYPE_CHECKING, ClassVar
 
 from dvsim.launcher.base import ErrorMessage, Launcher, LauncherError
 from dvsim.logging import log
 from dvsim.utils import clean_odirs
 
+if TYPE_CHECKING:
+    from dvsim.job.deploy import Deploy, WorkspaceConfig
+
+__all__ = ("LsfLauncher",)
+
 
 class LsfLauncher(Launcher):
+    """Launcher for IBM Spectrum LSF."""
+
     # A hidden directory specific to a cfg, where we put individual 'job'
     # scripts.
-    jobs_dir = {}
+    jobs_dir: ClassVar = {}
 
     # All launcher instances available for lookup.
-    jobs = {}
+    jobs: ClassVar = {}
 
     # When the job completes, we try to read the job script output to determine
     # the outcome. It may not have been completely written the first time we
@@ -32,40 +40,63 @@ class LsfLauncher(Launcher):
     #       `DVSIM_LSF_CFG` environment variable.
 
     @staticmethod
-    def prepare_workspace(project, repo_top, args) -> None:
+    def prepare_workspace(cfg: "WorkspaceConfig") -> None:
+        """Prepare the workspace for a cfg.
+
+        This is invoked once for each cfg.
+        'cfg' is the flow configuration object.
+
+        Args:
+            cfg: workspace configuration
+
+        """
         # Since we dispatch to remote machines, a project specific python
         # virtualenv is exists, needs to be activated when launching the job.
-        Launcher.set_pyvenv(project)
-        if Launcher.pyvenv is None:
+        Launcher.set_pyvenv(cfg.project)
+
+        pyvenv = Launcher.pyvenv
+        if pyvenv is None:
             return
 
         # If it is already a dir, then nothing to be done.
-        if os.path.isdir(Launcher.pyvenv):  # noqa: PTH112
+        if pyvenv.is_dir():
             return
 
         # If not, then it needs to be a valid tarball. Extract it in the
         # scratch area if it does not exist.
-        stem = Path(Launcher.pyvenv).stem
+        stem = pyvenv.stem
         if stem.endswith("tar"):
             stem = stem[:-4]
-        path = Path(args.scratch_root, stem)
+
+        path = cfg.scratch_root / stem
         if not path.is_dir():
-            log.info("[prepare_workspace]: [pyvenv]: Extracting %s", Launcher.pyvenv)
+            log.info("[prepare_workspace]: [pyvenv]: Extracting %s", pyvenv)
             with tarfile.open(Launcher.pyvenv, mode="r") as tar:
-                tar.extractall(args.scratch_root)
+                tar.extractall(cfg.scratch_root)
+
             log.info("[prepare_workspace]: [pyvenv]: Done: %s", path)
+
         Launcher.pyvenv = path
 
     @staticmethod
-    def prepare_workspace_for_cfg(cfg) -> None:
+    def prepare_workspace_for_cfg(cfg: "WorkspaceConfig") -> None:
+        """Prepare the workspace for a cfg.
+
+        This is invoked once for each cfg.
+        'cfg' is the flow configuration object.
+
+        Args:
+            cfg: workspace configuration
+
+        """
         # Create the job dir.
-        LsfLauncher.jobs_dir[cfg] = Path(cfg.scratch_path, "lsf", cfg.timestamp)
-        clean_odirs(odir=LsfLauncher.jobs_dir[cfg], max_odirs=2)
-        os.makedirs(Path(LsfLauncher.jobs_dir[cfg]), exist_ok=True)
+        LsfLauncher.jobs_dir[cfg.project] = cfg.scratch_path / "lsf" / cfg.timestamp
+        clean_odirs(odir=LsfLauncher.jobs_dir[cfg.project], max_odirs=2)
+        os.makedirs(Path(LsfLauncher.jobs_dir[cfg.project]), exist_ok=True)
 
     @staticmethod
-    def make_job_script(cfg, job_name):
-        """Creates the job script.
+    def make_job_script(cfg: "WorkspaceConfig", job_name: str):
+        """Create the job script.
 
         Once all jobs in the array are launched, the job script can be created.
         It is a bash script that takes the job index as a single argument.
@@ -76,7 +107,13 @@ def make_job_script(cfg, job_name):
         creating individual scripts for each job which incurs additional file
         I/O overhead when the scratch area is on NFS, causing a slowdown.
 
-        Returns the path to the job script.
+        Args:
+            cfg: workspace configuration
+            job_name: name of the job to run
+
+        Returns:
+            the path to the job script.
+
         """
         lines = ["#!/usr/bin/env bash\nset -e\n"]
 
@@ -95,10 +132,11 @@ def make_job_script(cfg, job_name):
         if Launcher.pyvenv:
             lines += ["deactivate\n"]
 
-        job_script = Path(LsfLauncher.jobs_dir[cfg], job_name)
+        job_script = LsfLauncher.jobs_dir[cfg] / job_name
         try:
             with open(job_script, "w", encoding="utf-8") as f:
                 f.writelines(lines)
+
         except OSError as e:
             err_msg = f"ERROR: Failed to write {job_script}:\n{e}"
             LsfLauncher._post_finish_job_array(cfg, job_name, err_msg)
@@ -107,7 +145,13 @@ def make_job_script(cfg, job_name):
         log.verbose("[job_script]: %s", job_script)
         return job_script
 
-    def __init__(self, deploy) -> None:
+    def __init__(self, deploy: "Deploy") -> None:
+        """Initialise the LSF Launcher.
+
+        Args:
+            deploy: job to remotely deploy.
+
+        """
         super().__init__(deploy)
 
         # Maintain the job script output as an instance variable for polling
@@ -136,10 +180,11 @@ def __init__(self, deploy) -> None:
         self.index = len(job_name_list)
 
     def _do_launch(self) -> None:
+        """Launch the job."""
         # Add self to the list of jobs.
         job_name = self.deploy.job_name
-        cfg = self.deploy.sim_cfg
-        job_total = len(LsfLauncher.jobs[cfg][job_name])
+        cfg = self.deploy.workspace_cfg
+        job_total = len(LsfLauncher.jobs[cfg.project][job_name])
 
         # The actual launching of the bsub command cannot happen until the
         # Scheduler has dispatched ALL jobs in the array.
@@ -211,13 +256,15 @@ def _do_launch(self) -> None:
             # Need to mark all jobs in this range with this fail pattern.
             err_msg = e.stderr.decode("utf-8").strip()
             self._post_finish_job_array(cfg, job_name, err_msg)
-            raise LauncherError(err_msg)
+
+            raise LauncherError(err_msg) from e
 
         # Extract the job ID.
         result = p.stdout.decode("utf-8").strip()
         job_id = result.split("Job <")[1].split(">")[0]
         if not job_id:
             self._post_finish_job_array(cfg, job_name, "Job ID not found!")
+            err_msg = f"job (id:{job_id}) not found"
             raise LauncherError(err_msg)
 
         for job in LsfLauncher.jobs[cfg][job_name]:
@@ -225,7 +272,13 @@ def _do_launch(self) -> None:
             job.job_id = f"{job_id}[{job.index}]"
             job._link_odir("D")
 
-    def poll(self):
+    def poll(self) -> str | None:
+        """Poll the status of the job.
+
+        Returns:
+            status of the job or None
+
+        """
         # It is possible we may have determined the status already.
         if self.status:
             return self.status
@@ -243,6 +296,7 @@ def poll(self):
             try:
                 if not self.bsub_out.stat().st_size:
                     return "D"
+
             except FileNotFoundError:
                 return "D"
 
@@ -250,6 +304,7 @@ def poll(self):
             # file for reading.
             try:
                 self.bsub_out_fd = open(self.bsub_out)
+
             except OSError as e:
                 self._post_finish(
                     "F",
@@ -283,7 +338,7 @@ def poll(self):
         # will resume reading it again at the next poll. We will do this upto
         # max_poll_retries times before giving up and flagging an error.
         #
-        # TODO: Consider using the IBM Plarform LSF Python APIs instead.
+        # TODO: Consider using the IBM Platform LSF Python APIs instead.
         #       (deferred due to shortage of time / resources).
         # TODO: Parse job telemetry data for performance insights.
 
@@ -306,15 +361,18 @@ def poll(self):
         if self.num_poll_retries == LsfLauncher.max_poll_retries:
             self._post_finish(
                 "F",
-                "ERROR: Reached max retries while "
-                f"reading job script output {self.bsub_out} to determine"
-                " the outcome.",
+                ErrorMessage(
+                    message="ERROR: Reached max retries while "
+                    f"reading job script output {self.bsub_out} to determine"
+                    " the outcome.",
+                    context=[],
+                ),
             )
             return "F"
 
         return "D"
 
-    def _get_job_exit_code(self):
+    def _get_job_exit_code(self) -> int | None:
         """Read the job script output to retrieve the exit code.
 
         Also read the error message if any, which will appear at the beginning
@@ -337,7 +395,9 @@ def _get_job_exit_code(self):
         indicating whether it was successful or it failed with an exit code
         is used to return the exit code.
 
-        Returns the exit code if found, else None.
+        Returns:
+            the exit code if found, else None.
+
         """
         # Job script output must have been opened already.
         assert self.bsub_out_fd
@@ -364,6 +424,7 @@ def _get_job_exit_code(self):
         return None
 
     def kill(self) -> None:
+        """Kill the remote job."""
         if self.job_id:
             try:
                 subprocess.run(
@@ -376,9 +437,10 @@ def kill(self) -> None:
         else:
             log.error("Job ID for %s not found", self.deploy.full_name)
 
-        self._post_finish("K", "Job killed!")
+        self._post_finish("K", ErrorMessage(message="Job killed!", context=[]))
 
-    def _post_finish(self, status, err_msg) -> None:
+    def _post_finish(self, status: str, err_msg: ErrorMessage) -> None:
+        """Tidy up after the job is complete."""
         if self.bsub_out_fd:
             self.bsub_out_fd.close()
         if self.exit_code is None:
@@ -386,12 +448,20 @@ def _post_finish(self, status, err_msg) -> None:
         super()._post_finish(status, err_msg)
 
     @staticmethod
-    def _post_finish_job_array(cfg, job_name, err_msg) -> None:
+    def _post_finish_job_array(
+        cfg: "WorkspaceConfig",
+        job_name: str,
+        err_msg: str,
+    ) -> None:
         """On LSF error, mark all jobs in this array as killed.
 
-        err_msg is the error message indicating the cause of failure.
+        Args:
+            cfg: workspace configuration
+            job_name: name of the job to run
+            err_msg: is the error message indicating the cause of failure.
+
         """
-        for job in LsfLauncher.jobs[cfg][job_name]:
+        for job in LsfLauncher.jobs[cfg.project][job_name]:
             job._post_finish(
                 "F",
                 ErrorMessage(line_number=None, message=err_msg, context=[err_msg]),
diff --git a/src/dvsim/launcher/nc.py b/src/dvsim/launcher/nc.py
index 2a5af9f7..ba7cc865 100644
--- a/src/dvsim/launcher/nc.py
+++ b/src/dvsim/launcher/nc.py
@@ -9,12 +9,15 @@
 import pathlib
 import subprocess
 import sys
-from collections.abc import Mapping
+from typing import TYPE_CHECKING
 
 from dvsim.launcher.base import ErrorMessage, Launcher, LauncherError
 from dvsim.logging import log
 from dvsim.utils import rm_path
 
+if TYPE_CHECKING:
+    from dvsim.job.deploy import WorkspaceConfig
+
 
 class NcLauncher(Launcher):
     """Implementation of Launcher to launch jobs using altair nc."""
@@ -45,7 +48,7 @@ def create_run_sh(self, full_path, cmd) -> None:
             "echo Launch end : `date`",
             "echo CPU time : $SECONDS sec",
         ]
-        with open(run_file, "w") as f:
+        with pathlib.Path(run_file).open("w") as f:
             f.write("\n".join(lines))
         pathlib.Path(run_file).chmod(0o755)
 
@@ -266,22 +269,23 @@ def _close_process(self) -> None:
             self.process.stdout.close()
 
     @staticmethod
-    def prepare_workspace(project: str, repo_top: str, args: Mapping) -> None:
+    def prepare_workspace(cfg: "WorkspaceConfig") -> None:
         """Prepare the workspace based on the chosen launcher's needs.
 
         This is done once for the entire duration for the flow run.
 
         Args:
-            project: the name of the project.
-            repo_top: the path to the repository.
-            args: command line args passed to dvsim.
+            cfg: workspace configuration
 
         """
 
     @staticmethod
-    def prepare_workspace_for_cfg(cfg: Mapping) -> None:
+    def prepare_workspace_for_cfg(cfg: "WorkspaceConfig") -> None:
         """Prepare the workspace for a cfg.
 
         This is invoked once for each cfg.
-        'cfg' is the flow configuration object.
+
+        Args:
+            cfg: workspace configuration
+
         """
diff --git a/src/dvsim/launcher/sge/launcher.py b/src/dvsim/launcher/sge/launcher.py
index 0d759762..3989d175 100644
--- a/src/dvsim/launcher/sge/launcher.py
+++ b/src/dvsim/launcher/sge/launcher.py
@@ -8,12 +8,15 @@
 import pathlib
 import shlex
 import subprocess
-from collections.abc import Mapping
 from subprocess import PIPE, Popen
+from typing import TYPE_CHECKING
 
 from dvsim.launcher.base import ErrorMessage, Launcher, LauncherError
 from dvsim.launcher.sge.engine import *  # noqa: F403
 
+if TYPE_CHECKING:
+    from dvsim.job.deploy import WorkspaceConfig
+
 global job_name
 
 pid = os.getpid()
@@ -167,22 +170,23 @@ def _close_process(self) -> None:
             self.process.stdout.close()
 
     @staticmethod
-    def prepare_workspace(project: str, repo_top: str, args: Mapping) -> None:
+    def prepare_workspace(cfg: "WorkspaceConfig") -> None:
         """Prepare the workspace based on the chosen launcher's needs.
 
         This is done once for the entire duration for the flow run.
 
         Args:
-            project: the name of the project.
-            repo_top: the path to the repository.
-            args: command line args passed to dvsim.
+            cfg: workspace configuration
 
         """
 
     @staticmethod
-    def prepare_workspace_for_cfg(cfg: Mapping) -> None:
+    def prepare_workspace_for_cfg(cfg: "WorkspaceConfig") -> None:
         """Prepare the workspace for a cfg.
 
         This is invoked once for each cfg.
-        'cfg' is the flow configuration object.
+
+        Args:
+            cfg: workspace configuration
+
         """
diff --git a/src/dvsim/launcher/slurm.py b/src/dvsim/launcher/slurm.py
index e631a556..d246d31d 100644
--- a/src/dvsim/launcher/slurm.py
+++ b/src/dvsim/launcher/slurm.py
@@ -7,11 +7,14 @@
 import shlex
 import shutil
 import subprocess
-from collections.abc import Mapping
+from typing import TYPE_CHECKING
 
 from dvsim.launcher.base import ErrorMessage, Launcher, LauncherError
 from dvsim.logging import log
 
+if TYPE_CHECKING:
+    from dvsim.job.deploy import WorkspaceConfig
+
 SLURM_QUEUE = os.environ.get("SLURM_QUEUE", "hw-m")
 SLURM_MEM = os.environ.get("SLURM_MEM", "16G")
 SLURM_MINCPUS = os.environ.get("SLURM_MINCPUS", "8")
@@ -149,22 +152,23 @@ def _close_process(self) -> None:
             self.process.stdout.close()
 
     @staticmethod
-    def prepare_workspace(project: str, repo_top: str, args: Mapping) -> None:
+    def prepare_workspace(cfg: "WorkspaceConfig") -> None:
         """Prepare the workspace based on the chosen launcher's needs.
 
         This is done once for the entire duration for the flow run.
 
         Args:
-            project: the name of the project.
-            repo_top: the path to the repository.
-            args: command line args passed to dvsim.
+            cfg: workspace configuration
 
         """
 
     @staticmethod
-    def prepare_workspace_for_cfg(cfg: Mapping) -> None:
+    def prepare_workspace_for_cfg(cfg: "WorkspaceConfig") -> None:
         """Prepare the workspace for a cfg.
 
         This is invoked once for each cfg.
-        'cfg' is the flow configuration object.
+
+        Args:
+            cfg: workspace configuration
+
         """
diff --git a/src/dvsim/scheduler.py b/src/dvsim/scheduler.py
index dc5bf0d2..de5f9041 100644
--- a/src/dvsim/scheduler.py
+++ b/src/dvsim/scheduler.py
@@ -91,7 +91,14 @@ def __init__(
         *,
         interactive: bool,
     ) -> None:
-        """Initialise a job scheduler."""
+        """Initialise a job scheduler.
+
+        Args:
+            items: sequence of jobs to deploy.
+            launcher_cls: Launcher class to use to deploy the jobs.
+            interactive: launch the tools in interactive mode.
+
+        """
         self.items: Sequence[Deploy] = items
 
         # 'scheduled[target][cfg]' is a list of Deploy objects for the chosen
@@ -148,7 +155,7 @@ def __init__(
             msg = self.msg_fmt.format(0, 0, 0, 0, 0, self._total[target])
             self.status_printer.init_target(target=target, msg=msg)
 
-        # A map from the Deploy object names tracked by this class to their
+        # A map from the Deployment names tracked by this class to their
         # current status. This status is 'Q', 'D', 'P', 'F' or 'K',
         # corresponding to membership in the dicts above. This is not
         # per-target.
@@ -271,8 +278,13 @@ def _enqueue_successors(self, item: Deploy | None = None) -> None:
         them to _queued.
         """
         for next_item in self._get_successors(item):
-            assert next_item.full_name not in self.item_status
-            assert next_item not in self._queued[next_item.target]
+            if (
+                next_item.full_name in self.item_status
+                or next_item in self._queued[next_item.target]
+            ):
+                msg = f"Job {next_item.full_name} already scheduled"
+                raise RuntimeError(msg)
+
             self.item_status[next_item.full_name] = "Q"
             self._queued[next_item.target].append(next_item)
             self._unschedule_item(next_item)
@@ -281,6 +293,10 @@ def _cancel_successors(self, item: Deploy) -> None:
         """Cancel an item's successors.
 
         Recursively move them from _scheduled or _queued to _killed.
+
+        Args:
+            item: job whose successors are to be canceled.
+
         """
         items = list(self._get_successors(item))
         while items:
@@ -291,14 +307,17 @@ def _cancel_successors(self, item: Deploy) -> None:
     def _get_successors(self, item: Deploy | None = None) -> Sequence[Deploy]:
         """Find immediate successors of an item.
 
-        'item' is a job that has completed. We choose the target that follows
-        the 'item''s current target and find the list of successors whose
-        dependency list contains 'item'. If 'item' is None, we pick successors
-        from all cfgs, else we pick successors only from the cfg to which the
-        item belongs.
+        We choose the target that follows the 'item''s current target and find
+        the list of successors whose dependency list contains 'item'. If 'item'
+        is None, we pick successors from all cfgs, else we pick successors only
+        from the cfg to which the item belongs.
+
+        Args:
+            item: is a job that has completed.
+
+        Returns:
+            list of item's successors, or an empty list if there are none.
 
-        Returns the list of item's successors, or an empty list if there are
-        none.
         """
         if item is None:
             target = next(iter(self._scheduled))
@@ -320,8 +339,10 @@ def _get_successors(self, item: Deploy | None = None) -> Sequence[Deploy]:
             while not found:
                 if target == item.target:
                     found = True
+
                 try:
                     target = next(target_iterator)
+
                 except StopIteration:
                     return []
 
@@ -349,7 +370,15 @@ def _get_successors(self, item: Deploy | None = None) -> Sequence[Deploy]:
         return successors
 
     def _ok_to_enqueue(self, item: Deploy) -> bool:
-        """Return true if ALL dependencies of item are complete."""
+        """Check if all dependencies jobs are completed.
+
+        Args:
+            item: is a deployment job.
+
+        Returns:
+            true if ALL dependencies of item are complete.
+
+        """
         for dep in item.dependencies:
             # Ignore dependencies that were not scheduled to run.
             if dep not in self.items:
@@ -366,11 +395,18 @@ def _ok_to_enqueue(self, item: Deploy) -> bool:
         return True
 
     def _ok_to_run(self, item: Deploy) -> bool:
-        """Return true if the required dependencies have passed.
+        """Check if a job is ready to start.
 
         The item's needs_all_dependencies_passing setting is used to figure
         out whether we can run this item or not, based on its dependent jobs'
         statuses.
+
+        Args:
+            item: is a deployment job.
+
+        Returns:
+            true if the required dependencies have passed.
+
         """
         # 'item' can run only if its dependencies have passed (their results
         # should already show up in the item to status map).
@@ -395,7 +431,9 @@ def _ok_to_run(self, item: Deploy) -> bool:
     def _poll(self, hms: str) -> bool:
         """Check for running items that have finished.
 
-        Returns True if something changed.
+        Returns:
+            True if something changed.
+
         """
         max_poll = min(
             self.launcher_cls.max_poll,
@@ -615,6 +653,11 @@ def _cancel_item(self, item: Deploy, *, cancel_successors: bool = True) -> None:
 
         Supplied item may be in _scheduled list or the _queued list. From
         either, we move it straight to _killed.
+
+        Args:
+            item: is a deployment job.
+            cancel_successors: if set then cancel successors as well (True).
+
         """
         self.item_status[item.full_name] = "K"
         self._killed[item.target].add(item)
@@ -627,7 +670,12 @@ def _cancel_item(self, item: Deploy, *, cancel_successors: bool = True) -> None:
             self._cancel_successors(item)
 
     def _kill_item(self, item: Deploy) -> None:
-        """Kill a running item and cancel all of its successors."""
+        """Kill a running item and cancel all of its successors.
+
+        Args:
+            item: is a deployment job.
+
+        """
         self._launchers[item.full_name].kill()
         self.item_status[item.full_name] = "K"
         self._killed[item.target].add(item)
diff --git a/src/dvsim/sim_utils.py b/src/dvsim/sim_utils.py
index 1c4f3149..48ee6c87 100644
--- a/src/dvsim/sim_utils.py
+++ b/src/dvsim/sim_utils.py
@@ -6,15 +6,19 @@
 
 import re
 from collections import OrderedDict
+from collections.abc import Sequence
+from io import TextIOWrapper
 from pathlib import Path
 
 
-def get_cov_summary_table(cov_report_txt: Path, tool: str):
+def get_cov_summary_table(
+    txt_cov_report: Path,
+    tool: str,
+) -> tuple[Sequence[Sequence[str]], str]:
     """Capture the summary results as a list of lists.
 
     The text coverage report is passed as input to the function, in addition to
-    the tool used. The tool returns a 2D list if the coverage report file was read
-    and the coverage was extracted successfully.
+    the tool used.
 
     Returns:
         tuple of, List of metrics and values, and final coverage total
@@ -23,7 +27,7 @@ def get_cov_summary_table(cov_report_txt: Path, tool: str):
         the appropriate exception if the coverage summary extraction fails.
 
     """
-    with Path(cov_report_txt).open() as f:
+    with Path(txt_cov_report).open() as f:
         if tool == "xcelium":
             return xcelium_cov_summary_table(f)
 
@@ -35,7 +39,8 @@ def get_cov_summary_table(cov_report_txt: Path, tool: str):
 
 
 # Same desc as above, but specific to Xcelium and takes an opened input stream.
-def xcelium_cov_summary_table(buf):
+def xcelium_cov_summary_table(buf: TextIOWrapper) -> tuple[Sequence[Sequence[str]], str]:
+    """Capture the summary results as a list of lists from Xcelium."""
     for line in buf:
         if "name" in line:
             # Strip the line and remove the unwanted "* Covered" string.
@@ -87,7 +92,8 @@ def xcelium_cov_summary_table(buf):
 
 
 # Same desc as above, but specific to VCS and takes an opened input stream.
-def vcs_cov_summary_table(buf):
+def vcs_cov_summary_table(buf: TextIOWrapper) -> tuple[Sequence[Sequence[str]], str]:
+    """Capture the summary results as a list of lists from VCS."""
     for line in buf:
         match = re.match("total coverage summary", line, re.IGNORECASE)
         if match:
@@ -124,7 +130,7 @@ def get_job_runtime(log_text: list, tool: str) -> tuple[float, str]:
         tool: is the EDA tool used to run the job.
 
     Returns:
-        the runtime, units as a tuple.
+        a tuple of (runtime, units).
 
     Raises:
         NotImplementedError: exception if the EDA tool is not supported.
@@ -184,8 +190,7 @@ def xcelium_job_runtime(log_text: list) -> tuple[float, str]:
     """
     pattern = r"^TOOL:\s*xrun.*: Exiting on .*\(total:\s*(\d+):(\d+):(\d+)\)\s*$"
     for line in reversed(log_text):
-        m = re.search(pattern, line)
-        if m:
+        if m := re.search(pattern, line):
             t = int(m.group(1)) * 3600 + int(m.group(2)) * 60 + int(m.group(3))
             return t, "s"
     msg = "Job runtime not found in the log."
@@ -265,9 +270,10 @@ def vcs_simulated_time(log_text: list) -> tuple[float, str]:
     next_line = ""
 
     for line in reversed(log_text):
-        if "V C S   S i m u l a t i o n   R e p o r t" in line and (
-            m := re.search(pattern, next_line)
-        ):
+        if "V C S   S i m u l a t i o n   R e p o r t" not in line:
+            continue
+
+        if m := re.search(pattern, next_line):
             return float(m.group(1)), m.group(2).lower()
 
         next_line = line
diff --git a/tests/job/test_deploy.py b/tests/job/test_deploy.py
new file mode 100644
index 00000000..7f3c8254
--- /dev/null
+++ b/tests/job/test_deploy.py
@@ -0,0 +1,219 @@
+# Copyright lowRISC contributors (OpenTitan project).
+# Licensed under the Apache License, Version 2.0, see LICENSE for details.
+# SPDX-License-Identifier: Apache-2.0
+
+"""Test Job deployment models."""
+
+from collections.abc import Mapping
+
+import pytest
+from hamcrest import assert_that, equal_to
+
+from dvsim.job.deploy import CompileSim
+
+__all__ = ()
+
+
+class FakeCliArgs:
+    """Fake CLI args."""
+
+    def __init__(self) -> None:
+        """Initialise fake command line arguments."""
+        self.build_timeout_mins = None
+        self.timestamp = "timestamp"
+
+
+class FakeSimCfg:
+    """Fake sim configuration."""
+
+    def __init__(self) -> None:
+        """Initialise fake sim configuration."""
+        self.name = "flow_name"
+        self.variant = "variant"
+
+        self.args = FakeCliArgs()
+        self.dry_run = True
+        self.gui = False
+
+        self.scratch_path = "/scratch_path"
+        self.scratch_root = "/scratch_root"
+        self.proj_root = "/project"
+
+        self.exports = []
+
+        self.flow_makefile = "path/to/makefile"
+        self.build_cmd = "path/to/{build_mode}/build_cmd"
+        self.pre_build_cmds = ["A", "B"]
+        self.post_build_cmds = ["C", "D"]
+        self.build_dir = "build/dir"
+        self.build_pass_patterns = None
+        self.build_fail_patterns = None
+        self.build_seed = 123
+
+        self.sv_flist_gen_cmd = "gen_cmd"
+        self.sv_flist_gen_opts = []
+        self.sv_flist_gen_dir = "path/to/gen"
+
+        self.cov = True
+        self.cov_db_dir = "path"
+
+
+class FakeBuildMode:
+    """Fake BuildMode."""
+
+    def __init__(self) -> None:
+        """Initialise fake BuildMode."""
+        self.name = "build_name"
+        self.build_timeout_mins = 500
+        self.build_mode = "build_mode"
+        self.build_opts = ["-b path/here", '-a "Quoted"']
+
+
+def _build_compile_sim(
+    *,
+    build_overrides: Mapping | None = None,
+    sim_overrides: Mapping | None = None,
+    cli_args_overrides: Mapping | None = None,
+) -> CompileSim:
+    """Build CompileSim object.
+
+    Test helper that takes overrides to apply on top of the default values for
+    the BuildMode and SimCfg fake objects.
+    """
+    cli_args = FakeCliArgs()
+    if cli_args_overrides:
+        for arg, value in cli_args_overrides.items():
+            setattr(cli_args, arg, value)
+
+    build_mode_obj = FakeBuildMode()
+    if build_overrides:
+        for arg, value in build_overrides.items():
+            setattr(build_mode_obj, arg, value)
+
+    sim_cfg = FakeSimCfg()
+    if sim_overrides:
+        for arg, value in sim_overrides.items():
+            setattr(sim_cfg, arg, value)
+
+    # Override the cli args in the sim configuration
+    sim_cfg.args = cli_args
+
+    return CompileSim.new(
+        build_mode_obj=build_mode_obj,
+        sim_cfg=sim_cfg,
+    )
+
+
+class TestCompileSim:
+    """Test CompileSim."""
+
+    @staticmethod
+    @pytest.mark.parametrize(
+        ("build_overrides", "sim_overrides", "exp_cmd"),
+        [
+            (
+                {"dry_run": True},
+                {},
+                "make -f path/to/makefile build "
+                "-n "
+                "build_cmd=path/to/build_name/build_cmd "
+                "build_dir=build/dir "
+                "build_opts='-b path/here -a \"Quoted\"' "
+                "post_build_cmds='C && D' "
+                "pre_build_cmds='A && B' "
+                "proj_root=/project "
+                "sv_flist_gen_cmd=gen_cmd "
+                "sv_flist_gen_dir=path/to/gen "
+                "sv_flist_gen_opts=''",
+            ),
+            (
+                {"dry_run": False},
+                {},
+                "make -f path/to/makefile build "
+                "build_cmd=path/to/build_name/build_cmd "
+                "build_dir=build/dir "
+                "build_opts='-b path/here -a \"Quoted\"' "
+                "post_build_cmds='C && D' "
+                "pre_build_cmds='A && B' "
+                "proj_root=/project "
+                "sv_flist_gen_cmd=gen_cmd "
+                "sv_flist_gen_dir=path/to/gen "
+                "sv_flist_gen_opts=''",
+            ),
+        ],
+    )
+    def test_cmd(build_overrides: Mapping, sim_overrides: Mapping, exp_cmd: str) -> None:
+        """Test that a CompileSim has the expected cmd."""
+        job = _build_compile_sim(
+            build_overrides=build_overrides,
+            sim_overrides=sim_overrides,
+        )
+
+        assert_that(job.cmd, equal_to(exp_cmd))
+
+    @staticmethod
+    @pytest.mark.parametrize(
+        ("build_overrides", "sim_overrides", "name", "full_name"),
+        [
+            ({"name": "fred"}, {"variant": None}, "fred", "flow_name:fred"),
+            ({"name": "fred"}, {"variant": "v1"}, "fred", "flow_name_v1:fred"),
+            ({"name": "fred"}, {"name": "flow", "variant": None}, "fred", "flow:fred"),
+            ({"name": "george"}, {"variant": None}, "george", "flow_name:george"),
+            ({"name": "george"}, {"variant": "v2"}, "george", "flow_name_v2:george"),
+        ],
+    )
+    def test_names(
+        build_overrides: Mapping,
+        sim_overrides: Mapping,
+        name: str,
+        full_name: str,
+    ) -> None:
+        """Test that a CompileSim ends up with the expected names."""
+        job = _build_compile_sim(
+            build_overrides=build_overrides,
+            sim_overrides=sim_overrides,
+        )
+
+        assert_that(job.name, equal_to(name))
+        assert_that(job.qual_name, equal_to(name))
+        assert_that(job.full_name, equal_to(full_name))
+
+    @staticmethod
+    @pytest.mark.parametrize(
+        ("sim_overrides", "seed"),
+        [
+            ({"build_seed": 123}, 123),
+            ({"build_seed": 631}, 631),
+        ],
+    )
+    def test_seed(
+        sim_overrides: Mapping,
+        seed: int,
+    ) -> None:
+        """Test that a CompileSim ends up with the expected seed."""
+        job = _build_compile_sim(
+            sim_overrides=sim_overrides,
+        )
+
+        assert_that(job.seed, equal_to(seed))
+
+    @staticmethod
+    @pytest.mark.parametrize(
+        ("cli_args_overrides", "build_overrides", "timeout"),
+        [
+            ({"build_timeout_mins": 111}, {}, 111),
+            ({}, {"build_timeout_mins": 112}, 112),
+        ],
+    )
+    def test_timeout(
+        cli_args_overrides: Mapping,
+        build_overrides: Mapping,
+        timeout: int,
+    ) -> None:
+        """Test that a CompileSim ends up with the expected timeout."""
+        job = _build_compile_sim(
+            build_overrides=build_overrides,
+            cli_args_overrides=cli_args_overrides,
+        )
+
+        assert_that(job.build_timeout_mins, equal_to(timeout))