diff --git a/server/app.py b/server/app.py
index a1296ff..04d32f2 100644
--- a/server/app.py
+++ b/server/app.py
@@ -30,10 +30,12 @@ from flask import (
     make_response,
     redirect,
     request,
+    Response,
     send_file,
     url_for,
 )
 from flask.templating import render_template
+from flask.typing import ResponseReturnValue
 from markupsafe import Markup
 from pony.flask import Pony
 from pony import orm
@@ -137,16 +139,18 @@ def environ_timedelta_seconds(value: Union[int, str, timedelta]) -> int:
     return environ_timedelta(value) // timedelta(seconds=1)
 
 
-ConfigKeySetter: Callable[[str, Any], Any]
+ConfigKeySetter = Callable[[str, Any], None]
 ConfigSingleTranslator = Callable[[Any], Any]
 ConfigTranslatorIterable = Iterable[ConfigSingleTranslator]
 ConfigTranslatorCreator = Callable[[str], ConfigTranslatorIterable]
 
 
 def config_suffixer(
-    setter: ConfigKeySetter, prefix: str, lower: bool = True
+    setter: ConfigKeySetter,
+    prefix: str,
+    lower: bool = True,
 ) -> ConfigTranslatorCreator:
-    def creator(key: str):
+    def creator(key: str) -> ConfigTranslatorIterable:
         if not key.startswith(prefix):
             raise Exception(f"Environment key {key!r} is missing suffix {prefix!r}")
         new_key = key[len(prefix) :]
@@ -156,21 +160,21 @@ def config_suffixer(
     return creator
 
 
-def celery_config_setter(key: str, val: Any):
+def celery_config_setter(key: str, val: Any) -> None:
     flask_app.config["CELERY"][key] = val
 
 
 celery_config_same = config_suffixer(celery_config_setter, "CELERY_")
 
 
-def flask_config_setter(key: str, val: Any):
+def flask_config_setter(key: str, val: Any) -> None:
     flask_app.config[key] = val
 
 
 flask_config_same = config_suffixer(flask_config_setter, "FLASK_", lower=False)
 
 
-def pony_config_setter(key: str, val: Any):
+def pony_config_setter(key: str, val: Any) -> None:
     flask_app.config["PONY"][key] = val
 
 
@@ -238,8 +242,12 @@ def encode_options(opts: Mapping[str, Any]) -> str:
 
 
 @flask_app.template_global()
-def this_url(changed_args: Mapping[str, str] = {}):
-    view_args = dict(request.view_args)
+def this_url(changed_args: Mapping[str, str] = {}) -> str:
+    if request.endpoint is None:
+        raise Exception(
+            "this_url can only be used after successful endpoint matching (request.endpoint is still None)"
+        )
+    view_args = dict(request.view_args or {})
     get_args = request.args.to_dict()
     get_args.update(changed_args)
     return url_for(request.endpoint, **view_args) + (
@@ -248,7 +256,7 @@ def this_url(changed_args: Mapping[str, str] = {}):
 
 
 @flask_app.template_filter()
-def as_link(uri: str):
+def as_link(uri: str) -> Markup:
     uri = Markup.escape(uri)
     return Markup(f'<a href="{uri}">{uri}</a>')
 
@@ -265,7 +273,7 @@ TIMEDELTA_FORMAT = (
 
 
 @flask_app.template_filter("timedelta")
-def _filter_timedelta(seconds: Optional[int]) -> str:
+def _filter_timedelta(seconds: Optional[int]) -> Optional[str]:
     if seconds is None:
         return None
     delta = timedelta(seconds=seconds)
@@ -292,12 +300,12 @@ def _select_ids(cls: Type[T], ids: Iterable[int]) -> Query[T]:
 
 
 @flask_app.teardown_request
-def merge_query_stats(*_, **__):
+def merge_query_stats(*_: Any, **__: Any) -> None:
     db.merge_local_stats()
 
 
 @flask_app.route("/")
-def dashboard():
+def dashboard() -> ResponseReturnValue:
     # config
     began_limit = 8
     pinned_limit = 16
@@ -313,18 +321,19 @@ def dashboard():
     pinned_collections: Iterable[MediaCollection] = orm.select(
         m for m in MediaCollection if m.pinned and not m.ignored
     ).order_by(MediaCollection.release_date, MediaCollection.title, MediaCollection.id)
-    links_from_pinned_collections = set[MediaCollectionLink]()
+    links_from_pinned_collections_set = set[MediaCollectionLink]()
     for coll in pinned_collections:
         next_link = coll.next_episode
         if (
             next_link is not None
-            and next_link not in links_from_pinned_collections
+            and next_link not in links_from_pinned_collections_set
             and next_link.element not in already_listed
             and next_link.element.can_considered
         ):
-            links_from_pinned_collections.add(next_link)
+            links_from_pinned_collections_set.add(next_link)
     links_from_pinned_collections = sorted(
-        links_from_pinned_collections, key=lambda l: l.element.release_date
+        links_from_pinned_collections_set,
+        key=lambda l: l.element.release_date,
     )[:pinned_limit]
     already_listed.update(link.element for link in links_from_pinned_collections)
     # for media
@@ -341,7 +350,7 @@ def dashboard():
     )
 
 
-def _list_collections(collections: Iterable[MediaCollection]):
+def _list_collections(collections: Iterable[MediaCollection]) -> ResponseReturnValue:
     return render_template(
         "collection_list.htm",
         collection_list=list(collections),
@@ -350,7 +359,7 @@ def _list_collections(collections: Iterable[MediaCollection]):
 
 def _list_collections_by_filter(
     filter: Callable[[MediaCollection], bool] = lambda _: True,
-):
+) -> ResponseReturnValue:
     collection_list: Iterable[MediaCollection] = orm.select(
         c for c in MediaCollection if filter(c)
     ).order_by(
@@ -362,22 +371,22 @@ def _list_collections_by_filter(
 
 
 @flask_app.route("/collection")
-def list_collection():
+def list_collection() -> ResponseReturnValue:
     return _list_collections_by_filter(lambda coll: coll.is_root_collection)
 
 
 @flask_app.route("/collection/all")
-def list_collection_all():
+def list_collection_all() -> ResponseReturnValue:
     return _list_collections_by_filter()
 
 
 @flask_app.route("/collection/extract")
-def extract_collection():
+def extract_collection() -> ResponseReturnValue:
     return render_template("collection_extract.htm")
 
 
 @flask_app.route("/collection/overview")
-def list_collection_overview():
+def list_collection_overview() -> ResponseReturnValue:
     data = request.args.to_dict()
     ids = _parse_cs_ids(data.get("ids", "NULL"))
     if not ids:
@@ -394,14 +403,14 @@ def list_collection_overview():
 
 
 @flask_app.route("/collection/to_watch")
-def list_collections_with_unwatched():
+def list_collections_with_unwatched() -> ResponseReturnValue:
     return _list_collections_by_filter(
         lambda coll: coll.is_root_collection and not coll.ignored and not coll.completed
     )
 
 
 @flask_app.route("/collection/pinned")
-def list_pinned_collection():
+def list_pinned_collection() -> ResponseReturnValue:
     collection_list: Iterable[MediaCollection] = orm.select(
         c for c in MediaCollection if c.pinned
     ).order_by(
@@ -413,7 +422,7 @@ def list_pinned_collection():
 
 
 @flask_app.route("/collection/<int:collection_id>")
-def show_collection(collection_id):
+def show_collection(collection_id: int) -> ResponseReturnValue:
     SMALL_COLLECTION_MAX_COUNT = 100
     collection: MediaCollection = MediaCollection.get(id=collection_id)
     if collection is None:
@@ -433,7 +442,7 @@ def show_collection(collection_id):
 
 
 @flask_app.route("/collection/<int:collection_id>/episodes")
-def show_collection_episodes(collection_id):
+def show_collection_episodes(collection_id: int) -> ResponseReturnValue:
     collection: MediaCollection = MediaCollection.get(id=collection_id)
     if collection is None:
         return make_response(f"Not found", 404)
@@ -448,7 +457,7 @@ def show_collection_episodes(collection_id):
 
 
 @flask_app.route("/media")
-def list_media():
+def list_media() -> ResponseReturnValue:
     media_list: Iterable[MediaElement] = get_all_considered(
         "elem.release_date DESC, elem.id"
     )
@@ -460,7 +469,7 @@ def list_media():
 
 @flask_app.route("/media/short")
 @flask_app.route("/media/short/<int:seconds>")
-def list_short_media(seconds: int = 10 * 60):
+def list_short_media(seconds: int = 10 * 60) -> ResponseReturnValue:
     media_list: Iterable[MediaElement] = get_all_considered(
         filter_by=f"(length - progress) <= {seconds}",
         order_by="elem.release_date DESC, elem.id",
@@ -468,12 +477,13 @@ def list_short_media(seconds: int = 10 * 60):
     return render_template(
         "media_list.htm",
         media_list=list(itertools.islice(media_list, 100)),
+        check_considered=False,
     )
 
 
 @flask_app.route("/media/long")
 @flask_app.route("/media/long/<int:seconds>")
-def list_long_media(seconds: int = 10 * 60):
+def list_long_media(seconds: int = 10 * 60) -> ResponseReturnValue:
     media_list: Iterable[MediaElement] = get_all_considered(
         filter_by=f"{seconds} <= (length - progress)",
         order_by="elem.release_date DESC, elem.id",
@@ -485,7 +495,7 @@ def list_long_media(seconds: int = 10 * 60):
 
 
 @flask_app.route("/media/unsorted")
-def list_unsorted_media():
+def list_unsorted_media() -> ResponseReturnValue:
     media_list: Iterable[MediaElement] = orm.select(
         m for m in MediaElement if len(m.collection_links) == 0
     ).order_by(orm.desc(MediaElement.release_date), MediaElement.id)
@@ -496,12 +506,12 @@ def list_unsorted_media():
 
 
 @flask_app.route("/media/extract")
-def extract_media():
+def extract_media() -> ResponseReturnValue:
     return render_template("media_extract.htm")
 
 
 @flask_app.route("/media/<int:media_id>")
-def show_media(media_id):
+def show_media(media_id: int) -> ResponseReturnValue:
     element: MediaElement = MediaElement.get(id=media_id)
     if element is None:
         return make_response(f"Not found", 404)
@@ -509,7 +519,7 @@ def show_media(media_id):
 
 
 @flask_app.route("/media/<int:media_id>/thumbnail")
-def show_media_thumb(media_id: int):
+def show_media_thumb(media_id: int) -> ResponseReturnValue:
     element: MediaElement = MediaElement.get(id=media_id)
     if element is None:
         # TODO add default thumbnail if not found
@@ -529,7 +539,7 @@ def show_media_thumb(media_id: int):
 
 
 @flask_app.route("/api/refresh/collections", methods=["POST"])
-def refresh_collections():
+def refresh_collections() -> ResponseReturnValue:
     collection_ids = set[int](
         orm.select(c.id for c in MediaCollection if c.keep_updated)
     )
@@ -575,7 +585,7 @@ def refresh_collections():
 
 
 @flask_app.route("/api/refresh/collection/<int:collection_id>", methods=["POST"])
-def force_refresh_collection(collection_id: int):
+def force_refresh_collection(collection_id: int) -> ResponseReturnValue:
     coll: MediaCollection = MediaCollection.get(id=collection_id)
     if coll is None:
         return "404 Not Found", 404
@@ -584,7 +594,7 @@ def force_refresh_collection(collection_id: int):
 
 
 @flask_app.route("/api/refresh/media/<int:media_id>", methods=["POST"])
-def force_refresh_media(media_id: int):
+def force_refresh_media(media_id: int) -> ResponseReturnValue:
     elem: MediaElement = MediaElement.get(id=media_id)
     if elem is None:
         return "404 Not Found", 404
@@ -593,7 +603,7 @@ def force_refresh_media(media_id: int):
 
 
 @flask_app.route("/stats")
-def show_stats():
+def show_stats() -> ResponseReturnValue:
     elements: List[MediaElement] = MediaElement.select()
     collections: List[MediaCollection] = MediaCollection.select()
     return render_template(
@@ -627,7 +637,7 @@ def show_stats():
 
 
 @flask_app.route("/stats/queries")
-def show_stats_queries():
+def show_stats_queries() -> ResponseReturnValue:
     stats = sorted(db.global_stats.values(), key=lambda s: s.sum_time, reverse=True)
     return render_template(
         "stats/queries.htm",
@@ -636,7 +646,7 @@ def show_stats_queries():
 
 
 @flask_app.route("/tag")
-def show_tag():
+def show_tag() -> ResponseReturnValue:
     tag_list: List[Tag] = Tag.select()
     return render_template(
         "tag_list.htm",
@@ -645,7 +655,7 @@ def show_tag():
 
 
 @flask_app.route("/debug/test")
-def test():
+def test() -> ResponseReturnValue:
     first: MediaElement = MediaElement.select().first()
     return {
         "data": first.to_dict(),
@@ -655,7 +665,7 @@ def test():
 # TODO add table for failed attempts so these may be resolved afterwards with increasing delays (add to MediaElement with flag "retrieved" and "last_updated" as date to resolve last try)
 
 
-def redirect_back_or_okay():
+def redirect_back_or_okay() -> Response:
     if "redirect" not in request.form:
         return make_response(
             {
@@ -664,13 +674,18 @@ def redirect_back_or_okay():
             200,
         )
     uri = request.form.get("redirect", type=str)
+    if uri is None:
+        raise Exception(f"IllegalState: uri should be set as checked before, but isn't")
     if not uri.startswith("/"):
-        return "400 Bad Request : Invalid Redirect Specified", 400
+        return make_response(
+            "400 Bad Request : Invalid Redirect Specified",
+            400,
+        )
     return redirect(uri)
 
 
 @flask_app.route("/api/collection/list")
-def api_collection_list():
+def api_collection_list() -> ResponseReturnValue:
     collection_list: Iterable[MediaCollection] = MediaCollection.select()
     return {
         "status": True,
@@ -688,7 +703,7 @@ def api_collection_list():
 
 
 @flask_app.route("/api/collection/extract", methods=["POST"])
-def api_collection_extract():
+def api_collection_extract() -> ResponseReturnValue:
     data = request.form.to_dict()
     if "uri" not in data:
         return {
@@ -704,7 +719,7 @@ def api_collection_extract():
     return redirect_back_or_okay()
 
 @flask_app.route("/api/collection/<int:collection_id>", methods=["GET", "POST"])
-def api_collection_element(collection_id: int):
+def api_collection_element(collection_id: int) -> ResponseReturnValue:
     collection: MediaCollection = MediaCollection.get(id=collection_id)
     if collection is None:
         return {
@@ -763,7 +778,7 @@ def api_collection_element(collection_id: int):
                 for m in query:
                     m.ignored = True
             del data["mark_unmarked_as"]
-        KEY_CONVERTER = {
+        KEY_CONVERTER: Mapping[str, Callable[[str], Any]] = {
             "title": str,
             "notes": str,
             "pinned": environ_bool,
@@ -791,7 +806,7 @@ def api_collection_element(collection_id: int):
 
 @flask_app.route("/api/collection/<int:collection_id>", methods=["DELETE"])
 @flask_app.route("/api/collection/<int:collection_id>/delete", methods=["POST"])
-def api_collection_delete(collection_id: int):
+def api_collection_delete(collection_id: int) -> ResponseReturnValue:
     collection: MediaCollection = MediaCollection.get(id=collection_id)
     if collection is None:
         return {
@@ -803,7 +818,7 @@ def api_collection_delete(collection_id: int):
 
 
 @flask_app.route("/api/media/list")
-def api_media_list():
+def api_media_list() -> ResponseReturnValue:
     media_list: Iterable[MediaElement] = MediaElement.select()
     return {
         "status": True,
@@ -821,7 +836,7 @@ def api_media_list():
 
 
 @flask_app.route("/api/media/extract", methods=["POST"])
-def api_media_extract():
+def api_media_extract() -> ResponseReturnValue:
     data = request.form.to_dict()
     if "uri" not in data:
         return {
@@ -835,7 +850,7 @@ def api_media_extract():
     return redirect_back_or_okay()
 
 @flask_app.route("/api/media/<int:media_id>", methods=["GET", "POST"])
-def api_media_element(media_id: int):
+def api_media_element(media_id: int) -> ResponseReturnValue:
     element: MediaElement = MediaElement.get(id=media_id)
     if element is None:
         return {
@@ -872,7 +887,7 @@ def api_media_element(media_id: int):
         data = request.form.to_dict()
         if "redirect" in data:
             del data["redirect"]
-        KEY_CONVERTER = {
+        KEY_CONVERTER: Mapping[str, Callable[[str], Any]] = {
             "title": str,
             "notes": str,
             "progress": environ_timedelta_seconds,