diff --git a/allspice/allspice.py b/allspice/allspice.py
index 81cddc0..c5820e6 100644
--- a/allspice/allspice.py
+++ b/allspice/allspice.py
@@ -1,6 +1,6 @@
 import json
 import logging
-from typing import Dict, List, Optional, Union
+from typing import Any, Dict, List, Mapping, Optional, Union
 
 import requests
 import urllib3
@@ -92,7 +92,7 @@ def __get_url(self, endpoint):
         self.logger.debug("Url: %s" % url)
         return url
 
-    def __get(self, endpoint: str, params=frozendict()) -> requests.Response:
+    def __get(self, endpoint: str, params: Mapping = frozendict()) -> requests.Response:
         request = self.requests.get(self.__get_url(endpoint), headers=self.headers, params=params)
         if request.status_code not in [200, 201]:
             message = f"Received status code: {request.status_code} ({request.url})"
@@ -116,7 +116,7 @@ def parse_result(result) -> Dict:
             return json.loads(result.text)
         return {}
 
-    def requests_get(self, endpoint: str, params=frozendict(), sudo=None):
+    def requests_get(self, endpoint: str, params: Mapping = frozendict(), sudo=None):
         combined_params = {}
         combined_params.update(params)
         if sudo:
@@ -202,7 +202,9 @@ def requests_post(
         :return: The JSON response parsed as a dict
         """
 
-        args = {
+        # This should ideally be a TypedDict of the type of arguments taken by
+        # `requests.post`.
+        args: dict[str, Any] = {
             "headers": self.headers.copy(),
         }
         if data is not None:
@@ -258,14 +260,14 @@ def get_users(self) -> List[User]:
         results = self.requests_get(AllSpice.GET_USERS_ADMIN)
         return [User.parse_response(self, result) for result in results]
 
-    def get_user_by_email(self, email: str) -> User:
+    def get_user_by_email(self, email: str) -> Optional[User]:
         users = self.get_users()
         for user in users:
             if user.email == email or email in user.emails:
                 return user
         return None
 
-    def get_user_by_name(self, username: str) -> User:
+    def get_user_by_name(self, username: str) -> Optional[User]:
         users = self.get_users()
         for user in users:
             if user.username == username:
diff --git a/allspice/apiobject.py b/allspice/apiobject.py
index afdf66e..955242e 100644
--- a/allspice/apiobject.py
+++ b/allspice/apiobject.py
@@ -10,6 +10,7 @@
     Any,
     ClassVar,
     Dict,
+    FrozenSet,
     List,
     Literal,
     Optional,
@@ -19,6 +20,11 @@
     Union,
 )
 
+try:
+    from typing_extensions import Self
+except ImportError:
+    from typing import Self
+
 from .baseapiobject import ApiObject, ReadonlyApiObject
 from .exceptions import ConflictException, NotFoundException
 
@@ -70,7 +76,7 @@ def __hash__(self):
         return hash(self.allspice_client) ^ hash(self.name)
 
     @classmethod
-    def request(cls, allspice_client, name: str) -> "Organization":
+    def request(cls, allspice_client, name: str) -> Self:
         return cls._request(allspice_client, {"name": name})
 
     @classmethod
@@ -131,7 +137,7 @@ def create_repo(
         else:
             self.allspice_client.logger.error(result["message"])
             raise Exception("Repository not created... (gitea: %s)" % result["message"])
-        return Repository.parse_response(self, result)
+        return Repository.parse_response(self.allspice_client, result)
 
     def get_repositories(self) -> List["Repository"]:
         results = self.allspice_client.requests_get_paginated(
@@ -359,7 +365,7 @@ def create_repo(
         else:
             self.allspice_client.logger.error(result["message"])
             raise Exception("Repository not created... (gitea: %s)" % result["message"])
-        return Repository.parse_response(self, result)
+        return Repository.parse_response(self.allspice_client, result)
 
     def get_repositories(self) -> List["Repository"]:
         """Get all Repositories owned by this User."""
@@ -381,7 +387,7 @@ def get_teams(self) -> List["Team"]:
     def get_accessible_repos(self) -> List["Repository"]:
         """Get all Repositories accessible by the logged in User."""
         results = self.allspice_client.requests_get("/user/repos", sudo=self)
-        return [Repository.parse_response(self, result) for result in results]
+        return [Repository.parse_response(self.allspice_client, result) for result in results]
 
     def __request_emails(self):
         result = self.allspice_client.requests_get(User.USER_MAIL % self.login)
@@ -562,7 +568,7 @@ def __hash__(self):
             if r["email"] == ""
             else User.parse_response(allspice_client, r)
         ),
-        "updated_at": lambda allspice_client, t: Util.convert_time(t),
+        "updated_at": lambda _, t: Util.convert_time(t),
     }
 
     @classmethod
@@ -747,7 +753,6 @@ def get_issues(
             setattr(issue, "_repository", self)
             # This is mostly for compatibility with an older implementation
             Issue._add_read_property("repo", self, issue)
-            Issue._add_read_property("owner", self.owner, issue)
             issues.append(issue)
 
         return issues
@@ -909,7 +914,7 @@ def create_design_review(
         :return: The created Design Review
         """
 
-        data = {
+        data: dict[str, Any] = {
             "title": title,
         }
 
@@ -1002,11 +1007,11 @@ def remove_collaborator(self, user_name: str):
 
     def transfer_ownership(
         self,
-        new_owner: Union["User", "Organization"],
-        new_teams: Set["Team"] = frozenset(),
+        new_owner: Union[User, Organization],
+        new_teams: Set[Team] | FrozenSet[Team] = frozenset(),
     ):
         url = Repository.REPO_TRANSFER.format(owner=self.owner.username, repo=self.name)
-        data = {"new_owner": new_owner.username}
+        data: dict[str, Any] = {"new_owner": new_owner.username}
         if isinstance(new_owner, Organization):
             new_team_ids = [team.id for team in new_teams if team in new_owner.get_teams()]
             data["team_ids"] = new_team_ids
@@ -1014,10 +1019,10 @@ def transfer_ownership(
         # TODO: make sure this instance is either updated or discarded
 
     def get_git_content(
-        self: Optional[str] = None,
+        self,
         ref: Optional["Ref"] = None,
         commit: "Optional[Commit]" = None,
-    ) -> List["Content"]:
+    ) -> List[Content]:
         """
         Get a list of all files in the repository.
 
@@ -1430,8 +1435,8 @@ def __hash__(self):
         return hash(self.allspice_client) ^ hash(self.id)
 
     _fields_to_parsers: ClassVar[dict] = {
-        "closed_at": lambda allspice_client, t: Util.convert_time(t),
-        "due_on": lambda allspice_client, t: Util.convert_time(t),
+        "closed_at": lambda _, t: Util.convert_time(t),
+        "due_on": lambda _, t: Util.convert_time(t),
     }
 
     _patchable_fields: ClassVar[set[str]] = {
@@ -1508,10 +1513,10 @@ def __init__(self, allspice_client):
     def __eq__(self, other):
         if not isinstance(other, Comment):
             return False
-        return self.repo == other.repo and self.id == other.id
+        return self.repository == other.repository and self.id == other.id
 
     def __hash__(self):
-        return hash(self.repo) ^ hash(self.id)
+        return hash(self.repository) ^ hash(self.id)
 
     @classmethod
     def request(cls, allspice_client, owner: str, repo: str, id: str) -> "Comment":
@@ -1580,7 +1585,7 @@ def create_attachment(self, file: IO, name: Optional[str] = None) -> Attachment:
         :return: The created attachment.
         """
 
-        args = {
+        args: dict[str, Any] = {
             "files": {"attachment": file},
         }
         if name is not None:
@@ -1702,6 +1707,9 @@ def get_statuses(self) -> List[CommitStatus]:
     @cached_property
     def _fields_for_path(self) -> dict[str, str]:
         matches = self.URL_REGEXP.search(self.url)
+        if not matches:
+            raise ValueError(f"Invalid commit URL: {self.url}")
+
         return {
             "owner": matches.group(1),
             "repo": matches.group(2),
@@ -1717,7 +1725,7 @@ class CommitStatusState(Enum):
     WARNING = "warning"
 
     @classmethod
-    def try_init(cls, value: str) -> Union[CommitStatusState, str]:
+    def try_init(cls, value: str) -> CommitStatusState | str:
         """
         Try converting a string to the enum, and if that fails, return the
         string itself.
@@ -1726,7 +1734,7 @@ def try_init(cls, value: str) -> Union[CommitStatusState, str]:
         try:
             return cls(value)
         except ValueError:
-            value
+            return value
 
 
 class CommitStatus(ReadonlyApiObject):
@@ -1838,10 +1846,10 @@ def __init__(self, allspice_client):
     def __eq__(self, other):
         if not isinstance(other, Issue):
             return False
-        return self.repo == other.repo and self.id == other.id
+        return self.repository == other.repository and self.id == other.id
 
     def __hash__(self):
-        return hash(self.repo) ^ hash(self.id)
+        return hash(self.repository) ^ hash(self.id)
 
     _fields_to_parsers: ClassVar[dict] = {
         "milestone": lambda allspice_client, m: Milestone.parse_response(allspice_client, m),
@@ -1880,9 +1888,10 @@ def request(cls, allspice_client, owner: str, repo: str, number: str):
         api_object = cls._request(allspice_client, {"owner": owner, "repo": repo, "index": number})
         # The repository in the response is a RepositoryMeta object, so request
         # the full repository object and add it to the issue object.
-        repo = Repository.request(allspice_client, owner, repo)
-        setattr(api_object, "_repository", repo)
-        cls._add_read_property("repo", repo, api_object)
+        repository = Repository.request(allspice_client, owner, repo)
+        setattr(api_object, "_repository", repository)
+        # For legacy reasons
+        cls._add_read_property("repo", repository, api_object)
         return api_object
 
     @classmethod
@@ -1895,9 +1904,13 @@ def create_issue(cls, allspice_client, repo: Repository, title: str, body: str =
         cls._add_read_property("repo", repo, issue)
         return issue
 
+    @property
+    def owner(self) -> Organization | User:
+        return self.repository.owner
+
     def get_time_sum(self, user: User) -> int:
         results = self.allspice_client.requests_get(
-            Issue.GET_TIME % (self.owner.username, self.repo.name, self.number)
+            Issue.GET_TIME % (self.owner.username, self.repository.name, self.number)
         )
         return sum(result["time"] for result in results if result and result["user_id"] == user.id)
 
@@ -1921,7 +1934,7 @@ def get_comments(self) -> List[Comment]:
 
         results = self.allspice_client.requests_get(
             self.GET_COMMENTS.format(
-                owner=self.owner.username, repo=self.repo.name, index=self.number
+                owner=self.owner.username, repo=self.repository.name, index=self.number
             )
         )
 
@@ -1931,7 +1944,7 @@ def create_comment(self, body: str) -> Comment:
         """https://hub.allspice.io/api/swagger#/issue/issueCreateComment"""
 
         path = self.GET_COMMENTS.format(
-            owner=self.owner.username, repo=self.repo.name, index=self.number
+            owner=self.owner.username, repo=self.repository.name, index=self.number
         )
 
         response = self.allspice_client.requests_post(path, data={"body": body})
@@ -2004,10 +2017,10 @@ def __init__(self, allspice_client):
     def __eq__(self, other):
         if not isinstance(other, DesignReview):
             return False
-        return self.repo == other.repo and self.id == other.id
+        return self.repository == other.repository and self.id == other.id
 
     def __hash__(self):
-        return hash(self.repo) ^ hash(self.id)
+        return hash(self.repository) ^ hash(self.id)
 
     @classmethod
     def parse_response(cls, allspice_client, result) -> "DesignReview":
@@ -2224,6 +2237,7 @@ class Release(ApiObject):
     prerelease: bool
     published_at: str
     repo: Optional["Repository"]
+    repository: Optional["Repository"]
     tag_name: str
     tarball_url: str
     target_commitish: str
@@ -2262,6 +2276,8 @@ def __hash__(self):
     @classmethod
     def parse_response(cls, allspice_client, result, repo) -> Release:
         release = super().parse_response(allspice_client, result)
+        Release._add_read_property("repository", repo, release)
+        # For legacy reasons
         Release._add_read_property("repo", repo, release)
         setattr(
             release,
@@ -2283,8 +2299,8 @@ def request(
     ) -> Release:
         args = {"owner": owner, "repo": repo, "id": id}
         release_response = cls._get_gitea_api_object(allspice_client, args)
-        repo = Repository.request(allspice_client, owner, repo)
-        release = cls.parse_response(allspice_client, release_response, repo)
+        repository = Repository.request(allspice_client, owner, repo)
+        release = cls.parse_response(allspice_client, release_response, repository)
         return release
 
     def commit(self):
@@ -2302,7 +2318,7 @@ def create_asset(self, file: IO, name: Optional[str] = None) -> ReleaseAsset:
         :return: The created asset.
         """
 
-        args = {"files": {"attachment": file}}
+        args: dict[str, Any] = {"files": {"attachment": file}}
         if name is not None:
             args["params"] = {"name": name}
 
@@ -2453,12 +2469,13 @@ def __init__(self, allspice_client):
         super().__init__(allspice_client)
 
     def __eq__(self, other):
-        if not isinstance(other, Team):
+        if not isinstance(other, Content):
             return False
-        return self.repo == self.repo and self.sha == other.sha and self.name == other.name
+
+        return self.sha == other.sha and self.name == other.name
 
     def __hash__(self):
-        return hash(self.repo) ^ hash(self.sha) ^ hash(self.name)
+        return hash(self.sha) ^ hash(self.name)
 
 
 Ref = Union[Branch, Commit, str]
diff --git a/allspice/baseapiobject.py b/allspice/baseapiobject.py
index 75e7b04..06b4935 100644
--- a/allspice/baseapiobject.py
+++ b/allspice/baseapiobject.py
@@ -1,4 +1,14 @@
-from typing import ClassVar, Optional
+from __future__ import annotations
+
+from typing import TYPE_CHECKING, Any, ClassVar, Mapping, Optional
+
+try:
+    from typing_extensions import Self
+except ImportError:
+    from typing import Self
+
+if TYPE_CHECKING:
+    from allspice.allspice import AllSpice
 
 from .exceptions import MissingEqualityImplementation, ObjectIsInvalid, RawRequestEndpointMissing
 
@@ -8,46 +18,51 @@ def __init__(self, allspice_client):
         self.allspice_client = allspice_client
         self.deleted = False  # set if .delete was called, so that an exception is risen
 
-    def __str__(self):
+    def __str__(self) -> str:
         return "AllSpiceObject (%s):" % (type(self))
 
-    def __eq__(self, other):
+    def __eq__(self, other) -> bool:
         """Compare only fields that are part of the gitea-data identity"""
         raise MissingEqualityImplementation()
 
-    def __hash__(self):
+    def __hash__(self) -> int:
         """Hash only fields that are part of the gitea-data identity"""
         raise MissingEqualityImplementation()
 
     _fields_to_parsers: ClassVar[dict] = {}
 
+    # TODO: This should probably be made an abstract function as all children
+    # redefine it.
     @classmethod
-    def request(cls, allspice_client):
-        if hasattr("API_OBJECT", cls):
-            return cls._request(allspice_client)
-        else:
-            raise RawRequestEndpointMissing()
+    def request(cls, allspice_client: AllSpice) -> Self:
+        # This never would've worked, so maybe we should remove this function
+        # outright.
+        return cls._request(allspice_client)
 
     @classmethod
-    def _request(cls, allspice_client, args):
+    def _request(cls, allspice_client: AllSpice, args: Mapping) -> Self:
         result = cls._get_gitea_api_object(allspice_client, args)
         api_object = cls.parse_response(allspice_client, result)
         return api_object
 
     @classmethod
-    def _get_gitea_api_object(cls, allspice_client, args):
+    def _get_gitea_api_object(cls, allspice_client: AllSpice, args: Mapping) -> Mapping:
         """Retrieving an object always as GET_API_OBJECT"""
-        return allspice_client.requests_get(cls.API_OBJECT.format(**args))
+        if hasattr(cls, "API_OBJECT"):
+            raw_request_endpoint = getattr(cls, "API_OBJECT")
+            return allspice_client.requests_get(raw_request_endpoint.format(**args))
+        else:
+            raise RawRequestEndpointMissing()
 
     @classmethod
-    def parse_response(cls, allspice_client, result) -> "ReadonlyApiObject":
+    def parse_response(cls, allspice_client: AllSpice, result: Mapping) -> Self:
         # allspice_client.logger.debug("Found api object of type %s (id: %s)" % (type(cls), id))
         api_object = cls(allspice_client)
         cls._initialize(allspice_client, api_object, result)
         return api_object
 
     @classmethod
-    def _initialize(cls, allspice_client, api_object, result):
+    def _initialize(cls, allspice_client: AllSpice, api_object: Self, result: Mapping):
         for name, value in result.items():
             if name in cls._fields_to_parsers and value is not None:
                 parse_func = cls._fields_to_parsers[name]
@@ -59,7 +74,7 @@ def _initialize(cls, allspice_client, api_object, result):
                 cls._add_read_property(name, None, api_object)
 
     @classmethod
-    def _add_read_property(cls, name, value, api_object):
+    def _add_read_property(cls, name: str, value: Any, api_object: ReadonlyApiObject):
         if not hasattr(api_object, name):
             setattr(api_object, "_" + name, value)
             prop = property((lambda n: lambda self: self._get_var(n))(name))
@@ -67,7 +82,7 @@ def _add_read_property(cls, name, value, api_object):
         else:
             raise AttributeError(f"Attribute {name} already exists on api object.")
 
-    def _get_var(self, name):
+    def _get_var(self, name: str) -> Any:
         if self.deleted:
             raise ObjectIsInvalid()
         return getattr(self, "_" + name)
@@ -76,21 +91,23 @@ def _get_var(self, name):
 class ApiObject(ReadonlyApiObject):
     _patchable_fields: ClassVar[set[str]] = set()
 
-    def __init__(self, allspice_client):
+    def __init__(self, allspice_client: AllSpice):
         super().__init__(allspice_client)
         self._dirty_fields = set()
 
-    def _commit(self, route_fields: dict, dirty_fields: Optional[dict] = None):
+    def _commit(self, route_fields: dict, dirty_fields: Optional[Mapping] = None):
         if self.deleted:
             raise ObjectIsInvalid()
         if not hasattr(self, "API_OBJECT"):
             raise RawRequestEndpointMissing()
 
+        raw_request_endpoint = getattr(self, "API_OBJECT")
+
         if dirty_fields is None:
             dirty_fields = self.get_dirty_fields()
 
         self.allspice_client.requests_patch(
-            self.API_OBJECT.format(**route_fields),
+            raw_request_endpoint.format(**route_fields),
             dirty_fields,
         )
         self._dirty_fields = set()
@@ -100,7 +117,7 @@ def commit(self):
 
     _parsers_to_fields: ClassVar[dict] = {}
 
-    def get_dirty_fields(self):
+    def get_dirty_fields(self) -> dict[str, Any]:
         dirty_fields_values = {}
         for field in self._dirty_fields:
             value = getattr(self, field)
@@ -111,13 +128,13 @@ def get_dirty_fields(self):
         return dirty_fields_values
 
     @classmethod
-    def _initialize(cls, allspice_client, api_object, result):
+    def _initialize(cls, allspice_client: AllSpice, api_object: Self, result: Mapping):
         super()._initialize(allspice_client, api_object, result)
         for name in cls._patchable_fields:
             cls._add_write_property(name, None, api_object)
 
     @classmethod
-    def _add_write_property(cls, name, value, api_object):
+    def _add_write_property(cls, name: str, value: Any, api_object: Self):
         if not hasattr(api_object, "_" + name):
             setattr(api_object, "_" + name, value)
         prop = property(
@@ -126,8 +143,8 @@ def _add_write_property(cls, name, value, api_object):
         )
         setattr(cls, name, prop)
 
-    def __set_var(self, name, i):
+    def __set_var(self, name: str, value: Any):
         if self.deleted:
             raise ObjectIsInvalid()
         self._dirty_fields.add(name)
-        setattr(self, "_" + name, i)
+        setattr(self, "_" + name, value)
diff --git a/allspice/utils/bom_generation.py b/allspice/utils/bom_generation.py
index 8695932..b1a85db 100644
--- a/allspice/utils/bom_generation.py
+++ b/allspice/utils/bom_generation.py
@@ -399,7 +399,7 @@ def generate_bom_for_system_capture(
 
 def _get_first_matching_key_value(
     alternatives: Union[list[str], str],
-    attributes: dict[str, str | None],
+    attributes: dict[str, str],
 ) -> Optional[str]:
     """
     Search for a series of alternative keys in a dictionary, and return the
@@ -437,7 +437,7 @@ def _map_attributes(
 
 def _group_entries(
     components: list[BomEntry],
-    group_by: list[str],
+    group_by: Optional[list[str]],
     columns_mapping: dict[str, ColumnConfig],
 ) -> list[BomEntry]:
     """
@@ -449,7 +449,7 @@ def _group_entries(
 
     # If grouping is off, we just add a quantity of 1 to each component and
     # return early.
-    if group_by is None:
+    if group_by is None or len(group_by) == 0:
         for component in components:
             component[QUANTITY_COLUMN_NAME] = "1"
         return components
@@ -496,7 +496,7 @@ def _group_entries(
     return rows
 
 
-def _remove_non_bom_components(components: list[dict[str, str]]) -> list[dict[str, str]]:
+def _remove_non_bom_components(components: list[ComponentAttributes]) -> list[ComponentAttributes]:
     """
     Filter out components of types that should not be included in the BOM.
     """
diff --git a/allspice/utils/list_components.py b/allspice/utils/list_components.py
index 9511a2c..da0afde 100644
--- a/allspice/utils/list_components.py
+++ b/allspice/utils/list_components.py
@@ -28,7 +28,7 @@
 # Maps a sheet name to a list of tuples, where each tuple is a child sheet and
 # the number of repetitions of that child sheet in the parent sheet.
 SchdocHierarchy = dict[str, list[tuple[str, int]]]
-ComponentAttributes = dict[str, str | None]
+ComponentAttributes = dict[str, str]
 
 
 class SupportedTool(Enum):
@@ -52,9 +52,9 @@ def list_components(
     repository: Repository,
     source_file: str,
     variant: Optional[str] = None,
-    ref: str = "main",
+    ref: Ref = "main",
     combine_multi_part: bool = False,
-) -> list[dict[str, str]]:
+) -> list[ComponentAttributes]:
     """
     Get a list of all components in a schematic.
 
@@ -128,9 +128,9 @@ def list_components_for_altium(
     repository: Repository,
     prjpcb_file: str,
     variant: Optional[str] = None,
-    ref: str = "main",
+    ref: Ref = "main",
     combine_multi_part: bool = False,
-) -> list[dict[str, str]]:
+) -> list[ComponentAttributes]:
     """
     Get a list of all components in an Altium project.
 
@@ -170,6 +170,9 @@ def list_components_for_altium(
                 f"Variant {variant} not found in PrjPcb file. "
                 "Please check the name of the variant."
             )
+    else:
+        # Ensuring variant_details is always bound, even if it is not used.
+        variant_details = None
 
     schdoc_files_in_proj = _extract_schdoc_list_from_prjpcb(prjpcb_ini)
     allspice_client.logger.info("Found %d SchDoc files", len(schdoc_files_in_proj))
@@ -213,6 +216,10 @@ def list_components_for_altium(
         components = _combine_multi_part_components_for_altium(components)
 
     if variant is not None:
+        if variant_details is None:
+            # This should never happen, but mypy doesn't know that.
+            raise ValueError(f"Variant {variant} not found in PrjPcb file.")
+
         components = _apply_variations(components, variant_details, allspice_client.logger)
 
     return components
@@ -222,9 +229,9 @@ def list_components_for_orcad(
     allspice_client: AllSpice,
     repository: Repository,
     dsn_path: str,
-    ref: str = "main",
+    ref: Ref = "main",
     combine_multi_part: bool = False,
-) -> list[dict[str, str]]:
+) -> list[ComponentAttributes]:
     """
     Get a list of all components in an OrCAD DSN schematic.
 
@@ -256,7 +263,7 @@ def list_components_for_system_capture(
     repository: Repository,
     sdax_path: str,
     ref: Ref = "main",
-) -> list[dict[str, str]]:
+) -> list[ComponentAttributes]:
     """
     Get a list of all components in a System Capture SDAX schematic.
 
@@ -310,7 +317,7 @@ def _list_components_multi_page_schematic(
     return components
 
 
-def _fetch_generated_json(repo: Repository, file_path: str, ref: str) -> dict:
+def _fetch_generated_json(repo: Repository, file_path: str, ref: Ref) -> dict:
     attempts = 0
     while attempts < 5:
         try:
@@ -635,10 +642,10 @@ def _extract_variations(
 
 
 def _apply_variations(
-    components: list[dict[str, str | None]],
+    components: list[dict[str, str]],
     variant_details: configparser.SectionProxy,
     logger: Logger,
-) -> list[dict[str, str | None]]:
+) -> list[dict[str, str]]:
     """
     Apply the variations of a specific variant to the components. This should be
     done before the components are mapped to columns or grouped.
@@ -661,7 +668,7 @@ def _apply_variations(
     patch_component_unique_id: dict[str, str] = {}
     # The keys are the same as above, and the values are a key-value of the
     # parameter to patch and the value to patch it to.
-    components_to_patch: dict[tuple[str, str], tuple[str, str]] = {}
+    components_to_patch: dict[tuple[str, str], list[tuple[str, str]]] = {}
 
     for key, value in variant_details.items():
         # Note that this is in lowercase, as configparser stores all keys in
diff --git a/allspice/utils/netlist_generation.py b/allspice/utils/netlist_generation.py
index 6b55687..3a4f228 100644
--- a/allspice/utils/netlist_generation.py
+++ b/allspice/utils/netlist_generation.py
@@ -28,7 +28,7 @@ class NetlistEntry:
     pins: list[str]
 
 
-Netlist = list[str]
+Netlist = dict[NetlistEntry, set[str]]
 
 
 def generate_netlist(
@@ -53,7 +53,17 @@ def generate_netlist(
     allspice_client.logger.info(f"Generating netlist for {repository.name=} on {ref=}")
     allspice_client.logger.info(f"Fetching {pcb_file=}")
 
-    pcb_components = _extract_all_pcb_components(allspice_client.logger, repository, ref, pcb_file)
+    if isinstance(pcb_file, Content):
+        pcb_file_path = pcb_file.path
+    else:
+        pcb_file_path = pcb_file
+
+    pcb_components = _extract_all_pcb_components(
+        allspice_client.logger,
+        repository,
+        ref,
+        pcb_file_path,
+    )
 
     return _group_netlist_entries(pcb_components)
 
@@ -96,7 +106,7 @@ def _extract_all_pcb_components(
     return components
 
 
-def _group_netlist_entries(components: list[PcbComponent]) -> dict[NetlistEntry]:
+def _group_netlist_entries(components: list[PcbComponent]) -> dict[NetlistEntry, set[str]]:
     """
     Group connected pins by the net
     """
diff --git a/requirements-test.txt b/requirements-test.txt
index 9171e24..0ce2ded 100644
--- a/requirements-test.txt
+++ b/requirements-test.txt
@@ -3,7 +3,10 @@ diff_cover~=9.1
 libcst~=1.4.0
 MonkeyType~=23.3
 pdoc~=14.5
+pyright~=1.1
 pytest-recording~=0.13
 pytest~=8.2
 ruff~=0.5
-syrupy~=4.6
\ No newline at end of file
+syrupy~=4.6
+types-requests~=2.32
+typing_extensions~=4.11; python_version < "3.11"
diff --git a/scripts/generate_attribute_types.py b/scripts/generate_attribute_types.py
index ad2680c..59ec9b2 100755
--- a/scripts/generate_attribute_types.py
+++ b/scripts/generate_attribute_types.py
@@ -28,6 +28,7 @@
 import monkeytype.stubs
 import monkeytype.typing
 import pytest
+from libcst import codemod
 from libcst.codemod.visitors import ApplyTypeAnnotationsVisitor
 
 HOOKED_FUNCTION_NAME = "parse_response"
@@ -305,7 +306,7 @@ def main():
 
     stub_module = cst.parse_module(module_stub.render())
     source_module = cst.parse_module(source)
-    context = cst.codemod.CodemodContext()
+    context = codemod.CodemodContext()
     CustomApplyTypeAnnotationsVisitor.store_stub_in_context(
         context,
         stub_module,
diff --git a/scripts/typecheck.sh b/scripts/typecheck.sh
new file mode 100755
index 0000000..f271eda
--- /dev/null
+++ b/scripts/typecheck.sh
@@ -0,0 +1,6 @@
+#!/usr/bin/env bash
+
+set -e
+set -u
+
+git ls-files | grep '\.py' | xargs pyright