From fafebf715da9e947c58177613b077e03cc8bbaae Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Robert=20Sch=C3=BCtz?= <nix@dotlambda.de>
Date: Thu, 27 Nov 2025 21:44:11 -0800
Subject: [PATCH 1/2] lib.concatAttrValues: init

This is useful for adding all optional-dependencies to the
nativeCheckInputs of Python packages.
---
 lib/default.nix |  1 +
 lib/lists.nix   | 24 +++++++++++++++++++++++-
 2 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/lib/default.nix b/lib/default.nix
index e10332ca58dd..044277fa24f5 100644
--- a/lib/default.nix
+++ b/lib/default.nix
@@ -303,6 +303,7 @@ let
         elem
         elemAt
         isList
+        concatAttrValues
         ;
       inherit (self.strings)
         concatStrings
diff --git a/lib/lists.nix b/lib/lists.nix
index fa2a526d1602..3be3715b9200 100644
--- a/lib/lists.nix
+++ b/lib/lists.nix
@@ -10,7 +10,7 @@ let
     id
     warn
     ;
-  inherit (lib.attrsets) mapAttrs attrNames;
+  inherit (lib.attrsets) mapAttrs attrNames attrValues;
   inherit (lib) max;
 in
 rec {
@@ -1997,4 +1997,26 @@ rec {
   */
   mutuallyExclusive = a: b: length a == 0 || !(any (x: elem x a) b);
 
+  /**
+    Concatenate all attributes of an attribute set.
+    This assumes that every attribute of the set is a list.
+
+    # Inputs
+
+    `set`
+
+    : Attribute set with attributes that are lists
+
+    # Examples
+    :::{.example}
+    ## `lib.concatAttrValues` usage example
+
+    ```nix
+    concatAttrValues { a = [ 1 2 ]; b = [ 3 ]; }
+    => [ 1 2 3 ]
+    ```
+
+    :::
+  */
+  concatAttrValues = set: concatLists (attrValues set);
 }

From 82c4e4f1ef9a89c1573b245d226d689651df569f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Robert=20Sch=C3=BCtz?= <nix@dotlambda.de>
Date: Thu, 27 Nov 2025 21:52:04 -0800
Subject: [PATCH 2/2] treewide: use lib.concatAttrValues to obtain all
 optional-dependencies

---
 .../networking/instant-messengers/pantalaimon/default.nix     | 2 +-
 pkgs/by-name/al/alpaca/package.nix                            | 2 +-
 pkgs/by-name/ca/calibre-web/package.nix                       | 2 +-
 pkgs/by-name/es/esptool/package.nix                           | 2 +-
 pkgs/by-name/ma/matrix-synapse-unwrapped/package.nix          | 2 +-
 pkgs/by-name/me/mediagoblin/package.nix                       | 2 +-
 pkgs/by-name/me/meerk40t/package.nix                          | 2 +-
 pkgs/by-name/mo/modelscan/package.nix                         | 2 +-
 pkgs/by-name/mu/music-assistant/package.nix                   | 2 +-
 pkgs/by-name/nb/nbqa/package.nix                              | 2 +-
 pkgs/by-name/pr/pretalx/package.nix                           | 2 +-
 pkgs/by-name/pr/pretix/package.nix                            | 2 +-
 pkgs/by-name/py/pyhanko-cli/package.nix                       | 2 +-
 pkgs/by-name/yt/yt-dlp/package.nix                            | 2 +-
 pkgs/development/python-modules/adb-shell/default.nix         | 2 +-
 pkgs/development/python-modules/aioboto3/default.nix          | 2 +-
 pkgs/development/python-modules/aiocache/default.nix          | 2 +-
 pkgs/development/python-modules/aioftp/default.nix            | 2 +-
 pkgs/development/python-modules/aiogram/default.nix           | 2 +-
 pkgs/development/python-modules/aiohomeconnect/default.nix    | 2 +-
 .../python-modules/aiohttp-client-cache/default.nix           | 2 +-
 pkgs/development/python-modules/aiohttp-fast-zlib/default.nix | 2 +-
 pkgs/development/python-modules/aiojobs/default.nix           | 2 +-
 pkgs/development/python-modules/aiomisc/default.nix           | 2 +-
 pkgs/development/python-modules/aioprometheus/default.nix     | 2 +-
 pkgs/development/python-modules/aiorpcx/default.nix           | 2 +-
 pkgs/development/python-modules/aiortm/default.nix            | 2 +-
 pkgs/development/python-modules/aiovlc/default.nix            | 2 +-
 pkgs/development/python-modules/alpha-vantage/default.nix     | 2 +-
 pkgs/development/python-modules/apischema/default.nix         | 2 +-
 pkgs/development/python-modules/apispec/default.nix           | 2 +-
 pkgs/development/python-modules/apptools/default.nix          | 2 +-
 pkgs/development/python-modules/arelle/default.nix            | 2 +-
 pkgs/development/python-modules/argilla/default.nix           | 2 +-
 pkgs/development/python-modules/asn1tools/default.nix         | 2 +-
 pkgs/development/python-modules/asyncssh/default.nix          | 2 +-
 pkgs/development/python-modules/avwx-engine/default.nix       | 2 +-
 pkgs/development/python-modules/azure-core/default.nix        | 2 +-
 pkgs/development/python-modules/azure-kusto-data/default.nix  | 2 +-
 .../development/python-modules/azure-kusto-ingest/default.nix | 2 +-
 pkgs/development/python-modules/banks/default.nix             | 2 +-
 pkgs/development/python-modules/basedmypy/default.nix         | 2 +-
 pkgs/development/python-modules/bc-detect-secrets/default.nix | 2 +-
 pkgs/development/python-modules/beanhub-cli/default.nix       | 4 ++--
 pkgs/development/python-modules/beautifulsoup4/default.nix    | 2 +-
 pkgs/development/python-modules/betterproto/default.nix       | 2 +-
 pkgs/development/python-modules/bimmer-connected/default.nix  | 2 +-
 pkgs/development/python-modules/black/default.nix             | 2 +-
 pkgs/development/python-modules/bpython/default.nix           | 2 +-
 .../python-modules/busylight-for-humans/default.nix           | 2 +-
 pkgs/development/python-modules/bytewax/default.nix           | 2 +-
 pkgs/development/python-modules/cachecontrol/default.nix      | 2 +-
 pkgs/development/python-modules/canals/default.nix            | 2 +-
 pkgs/development/python-modules/canmatrix/default.nix         | 2 +-
 pkgs/development/python-modules/cartopy/default.nix           | 2 +-
 pkgs/development/python-modules/cassandra-driver/default.nix  | 2 +-
 pkgs/development/python-modules/catppuccin/default.nix        | 2 +-
 pkgs/development/python-modules/celery/default.nix            | 2 +-
 pkgs/development/python-modules/cement/default.nix            | 2 +-
 pkgs/development/python-modules/certomancer/default.nix       | 2 +-
 pkgs/development/python-modules/cf-xarray/default.nix         | 2 +-
 pkgs/development/python-modules/cfn-lint/default.nix          | 2 +-
 pkgs/development/python-modules/channels/default.nix          | 2 +-
 pkgs/development/python-modules/cli-helpers/default.nix       | 2 +-
 .../python-modules/coinmetrics-api-client/default.nix         | 2 +-
 pkgs/development/python-modules/comicapi/default.nix          | 2 +-
 pkgs/development/python-modules/configargparse/default.nix    | 2 +-
 pkgs/development/python-modules/confluent-kafka/default.nix   | 2 +-
 pkgs/development/python-modules/connexion/default.nix         | 2 +-
 pkgs/development/python-modules/construct/default.nix         | 2 +-
 pkgs/development/python-modules/control/default.nix           | 2 +-
 .../python-modules/cyclonedx-python-lib/default.nix           | 2 +-
 pkgs/development/python-modules/cyclopts/default.nix          | 2 +-
 pkgs/development/python-modules/dask-awkward/default.nix      | 2 +-
 pkgs/development/python-modules/dataclass-wizard/default.nix  | 2 +-
 .../python-modules/datamodel-code-generator/default.nix       | 2 +-
 pkgs/development/python-modules/dateparser/default.nix        | 2 +-
 pkgs/development/python-modules/deepdiff/default.nix          | 2 +-
 .../python-modules/dependency-injector/default.nix            | 2 +-
 pkgs/development/python-modules/diffusers/default.nix         | 2 +-
 .../python-modules/dissect-cobaltstrike/default.nix           | 2 +-
 pkgs/development/python-modules/django-allauth/default.nix    | 2 +-
 pkgs/development/python-modules/django-bootstrap5/default.nix | 2 +-
 .../python-modules/django-import-export/default.nix           | 2 +-
 pkgs/development/python-modules/django-redis/default.nix      | 2 +-
 pkgs/development/python-modules/django-storages/default.nix   | 2 +-
 pkgs/development/python-modules/django-stubs/default.nix      | 2 +-
 pkgs/development/python-modules/django-tables2/default.nix    | 2 +-
 pkgs/development/python-modules/django/4.nix                  | 2 +-
 pkgs/development/python-modules/django/5_1.nix                | 2 +-
 pkgs/development/python-modules/django/5_2.nix                | 2 +-
 .../python-modules/djangorestframework-stubs/default.nix      | 2 +-
 pkgs/development/python-modules/docker/default.nix            | 2 +-
 pkgs/development/python-modules/dockerflow/default.nix        | 2 +-
 pkgs/development/python-modules/dparse/default.nix            | 2 +-
 pkgs/development/python-modules/dramatiq-abort/default.nix    | 2 +-
 pkgs/development/python-modules/dsnap/default.nix             | 2 +-
 pkgs/development/python-modules/dulwich/default.nix           | 2 +-
 pkgs/development/python-modules/edalize/default.nix           | 2 +-
 pkgs/development/python-modules/energyflow/default.nix        | 2 +-
 pkgs/development/python-modules/fastavro/default.nix          | 2 +-
 pkgs/development/python-modules/fastmcp/default.nix           | 2 +-
 pkgs/development/python-modules/fickling/default.nix          | 2 +-
 pkgs/development/python-modules/flask-dance/default.nix       | 2 +-
 .../development/python-modules/flask-jwt-extended/default.nix | 2 +-
 pkgs/development/python-modules/flask/default.nix             | 2 +-
 pkgs/development/python-modules/flow-record/default.nix       | 2 +-
 pkgs/development/python-modules/fnllm/default.nix             | 2 +-
 pkgs/development/python-modules/foolscap/default.nix          | 2 +-
 pkgs/development/python-modules/frictionless/default.nix      | 2 +-
 pkgs/development/python-modules/githubkit/default.nix         | 2 +-
 pkgs/development/python-modules/glom/default.nix              | 2 +-
 pkgs/development/python-modules/google-auth/default.nix       | 2 +-
 .../python-modules/google-cloud-spanner/default.nix           | 2 +-
 pkgs/development/python-modules/groq/default.nix              | 2 +-
 pkgs/development/python-modules/gruut/default.nix             | 2 +-
 pkgs/development/python-modules/gstools/default.nix           | 2 +-
 pkgs/development/python-modules/gunicorn/default.nix          | 2 +-
 pkgs/development/python-modules/hishel/default.nix            | 2 +-
 pkgs/development/python-modules/httpcore/default.nix          | 2 +-
 pkgs/development/python-modules/httpx/default.nix             | 2 +-
 pkgs/development/python-modules/hypercorn/default.nix         | 2 +-
 pkgs/development/python-modules/igraph/default.nix            | 2 +-
 pkgs/development/python-modules/imageio/default.nix           | 2 +-
 pkgs/development/python-modules/inline-snapshot/default.nix   | 2 +-
 pkgs/development/python-modules/intake/default.nix            | 2 +-
 pkgs/development/python-modules/iplotx/default.nix            | 2 +-
 pkgs/development/python-modules/joserfc/default.nix           | 2 +-
 pkgs/development/python-modules/jupyter-events/default.nix    | 2 +-
 pkgs/development/python-modules/kafka-python-ng/default.nix   | 2 +-
 pkgs/development/python-modules/keystoneauth1/default.nix     | 4 ++--
 pkgs/development/python-modules/kombu/default.nix             | 2 +-
 pkgs/development/python-modules/kserve/default.nix            | 2 +-
 pkgs/development/python-modules/kubernetes/default.nix        | 2 +-
 pkgs/development/python-modules/lance-namespace/default.nix   | 2 +-
 pkgs/development/python-modules/langgraph-cli/default.nix     | 2 +-
 pkgs/development/python-modules/libpass/default.nix           | 2 +-
 pkgs/development/python-modules/limits/default.nix            | 2 +-
 .../development/python-modules/llama-stack-client/default.nix | 2 +-
 pkgs/development/python-modules/logbook/default.nix           | 2 +-
 pkgs/development/python-modules/mako/default.nix              | 2 +-
 pkgs/development/python-modules/manifest-ml/default.nix       | 2 +-
 pkgs/development/python-modules/markdown2/default.nix         | 2 +-
 pkgs/development/python-modules/mashumaro/default.nix         | 2 +-
 pkgs/development/python-modules/mastodon-py/default.nix       | 2 +-
 pkgs/development/python-modules/mcp/default.nix               | 2 +-
 pkgs/development/python-modules/meshtastic/default.nix        | 2 +-
 pkgs/development/python-modules/minari/default.nix            | 2 +-
 pkgs/development/python-modules/mir-eval/default.nix          | 2 +-
 pkgs/development/python-modules/mne/default.nix               | 2 +-
 pkgs/development/python-modules/mocket/default.nix            | 2 +-
 pkgs/development/python-modules/modern-colorthief/default.nix | 2 +-
 pkgs/development/python-modules/moviepy/default.nix           | 2 +-
 pkgs/development/python-modules/mrjob/default.nix             | 2 +-
 pkgs/development/python-modules/mypy/default.nix              | 2 +-
 pkgs/development/python-modules/narwhals/default.nix          | 2 +-
 pkgs/development/python-modules/nibe/default.nix              | 2 +-
 pkgs/development/python-modules/nicegui/default.nix           | 2 +-
 pkgs/development/python-modules/noisereduce/default.nix       | 2 +-
 pkgs/development/python-modules/nox/default.nix               | 2 +-
 pkgs/development/python-modules/numcodecs/default.nix         | 2 +-
 pkgs/development/python-modules/nutils/default.nix            | 2 +-
 pkgs/development/python-modules/oauthenticator/default.nix    | 2 +-
 pkgs/development/python-modules/oauthlib/default.nix          | 2 +-
 pkgs/development/python-modules/odc-loader/default.nix        | 2 +-
 pkgs/development/python-modules/okonomiyaki/default.nix       | 2 +-
 pkgs/development/python-modules/openapi-core/default.nix      | 2 +-
 pkgs/development/python-modules/outlines-core/default.nix     | 2 +-
 pkgs/development/python-modules/pandas/default.nix            | 2 +-
 pkgs/development/python-modules/paramiko/default.nix          | 2 +-
 pkgs/development/python-modules/persist-queue/default.nix     | 2 +-
 pkgs/development/python-modules/pettingzoo/default.nix        | 2 +-
 pkgs/development/python-modules/piccolo/default.nix           | 2 +-
 pkgs/development/python-modules/pillow/default.nix            | 2 +-
 pkgs/development/python-modules/pins/default.nix              | 2 +-
 pkgs/development/python-modules/pipdeptree/default.nix        | 2 +-
 .../development/python-modules/planetary-computer/default.nix | 2 +-
 pkgs/development/python-modules/plotly/default.nix            | 2 +-
 pkgs/development/python-modules/plumbum/default.nix           | 2 +-
 pkgs/development/python-modules/powerapi/default.nix          | 2 +-
 pkgs/development/python-modules/pproxy/default.nix            | 2 +-
 pkgs/development/python-modules/prance/default.nix            | 2 +-
 pkgs/development/python-modules/prometheus-client/default.nix | 2 +-
 pkgs/development/python-modules/prowlpy/default.nix           | 2 +-
 pkgs/development/python-modules/pulsar-client/default.nix     | 2 +-
 pkgs/development/python-modules/py-sucks/default.nix          | 2 +-
 pkgs/development/python-modules/pycyphal/default.nix          | 2 +-
 pkgs/development/python-modules/pydantic/1.nix                | 2 +-
 pkgs/development/python-modules/pydantic/default.nix          | 2 +-
 pkgs/development/python-modules/pydruid/default.nix           | 2 +-
 pkgs/development/python-modules/pyecharts/default.nix         | 2 +-
 pkgs/development/python-modules/pygal/default.nix             | 2 +-
 pkgs/development/python-modules/pyhanko/default.nix           | 2 +-
 pkgs/development/python-modules/pyjwt/default.nix             | 2 +-
 pkgs/development/python-modules/pymatgen/default.nix          | 2 +-
 pkgs/development/python-modules/pymbolic/default.nix          | 2 +-
 pkgs/development/python-modules/pymodbus/default.nix          | 2 +-
 pkgs/development/python-modules/pymorphy3/default.nix         | 2 +-
 pkgs/development/python-modules/pynws/default.nix             | 2 +-
 pkgs/development/python-modules/pypiserver/default.nix        | 2 +-
 pkgs/development/python-modules/pyproject-parser/default.nix  | 2 +-
 pkgs/development/python-modules/pyrate-limiter/default.nix    | 2 +-
 pkgs/development/python-modules/pytablewriter/default.nix     | 2 +-
 pkgs/development/python-modules/pytest-aio/default.nix        | 2 +-
 pkgs/development/python-modules/pytest-benchmark/default.nix  | 2 +-
 pkgs/development/python-modules/pytest-jupyter/default.nix    | 2 +-
 .../development/python-modules/pytest-regressions/default.nix | 2 +-
 pkgs/development/python-modules/pytest-variables/default.nix  | 2 +-
 pkgs/development/python-modules/python-benedict/default.nix   | 2 +-
 pkgs/development/python-modules/python-dali/default.nix       | 2 +-
 pkgs/development/python-modules/python-engineio/default.nix   | 2 +-
 pkgs/development/python-modules/python-jose/default.nix       | 2 +-
 .../python-modules/python-matter-server/default.nix           | 2 +-
 pkgs/development/python-modules/python-socketio/default.nix   | 2 +-
 pkgs/development/python-modules/pythonfinder/default.nix      | 2 +-
 pkgs/development/python-modules/pytoolconfig/default.nix      | 2 +-
 .../python-modules/pytorch-metric-learning/default.nix        | 2 +-
 pkgs/development/python-modules/pyutil/default.nix            | 2 +-
 pkgs/development/python-modules/pywinrm/default.nix           | 2 +-
 pkgs/development/python-modules/qcelemental/default.nix       | 2 +-
 pkgs/development/python-modules/qcengine/default.nix          | 2 +-
 pkgs/development/python-modules/qrcode/default.nix            | 2 +-
 pkgs/development/python-modules/qutip/default.nix             | 2 +-
 pkgs/development/python-modules/ratarmountcore/default.nix    | 2 +-
 pkgs/development/python-modules/renault-api/default.nix       | 2 +-
 pkgs/development/python-modules/reptor/default.nix            | 2 +-
 pkgs/development/python-modules/sagemaker-core/default.nix    | 2 +-
 pkgs/development/python-modules/scholarly/default.nix         | 2 +-
 pkgs/development/python-modules/schwifty/default.nix          | 2 +-
 pkgs/development/python-modules/seabreeze/default.nix         | 2 +-
 pkgs/development/python-modules/seasonal/default.nix          | 2 +-
 pkgs/development/python-modules/securesystemslib/default.nix  | 2 +-
 .../python-modules/sentence-transformers/default.nix          | 2 +-
 pkgs/development/python-modules/sfrbox-api/default.nix        | 2 +-
 pkgs/development/python-modules/shiny/default.nix             | 2 +-
 pkgs/development/python-modules/shinychat/default.nix         | 2 +-
 pkgs/development/python-modules/simpful/default.nix           | 2 +-
 pkgs/development/python-modules/slack-bolt/default.nix        | 2 +-
 pkgs/development/python-modules/slixmpp/default.nix           | 2 +-
 pkgs/development/python-modules/smart-open/default.nix        | 2 +-
 pkgs/development/python-modules/smolagents/default.nix        | 2 +-
 pkgs/development/python-modules/social-auth-core/default.nix  | 2 +-
 pkgs/development/python-modules/speechrecognition/default.nix | 2 +-
 pkgs/development/python-modules/splinter/default.nix          | 2 +-
 pkgs/development/python-modules/sqlalchemy-utils/default.nix  | 2 +-
 pkgs/development/python-modules/sqlfmt/default.nix            | 2 +-
 pkgs/development/python-modules/sqlframe/default.nix          | 2 +-
 pkgs/development/python-modules/starlette/default.nix         | 2 +-
 pkgs/development/python-modules/static3/default.nix           | 2 +-
 pkgs/development/python-modules/stm32loader/default.nix       | 2 +-
 .../development/python-modules/strawberry-graphql/default.nix | 2 +-
 pkgs/development/python-modules/tabulate/default.nix          | 2 +-
 .../python-modules/textual-fastdatatable/default.nix          | 2 +-
 pkgs/development/python-modules/tianshou/default.nix          | 2 +-
 pkgs/development/python-modules/timezonefinder/default.nix    | 2 +-
 .../python-modules/trino-python-client/default.nix            | 2 +-
 pkgs/development/python-modules/tweepy/default.nix            | 2 +-
 pkgs/development/python-modules/typed-settings/default.nix    | 2 +-
 pkgs/development/python-modules/typepy/default.nix            | 2 +-
 pkgs/development/python-modules/types-lxml/default.nix        | 2 +-
 pkgs/development/python-modules/ufmt/default.nix              | 2 +-
 pkgs/development/python-modules/ufolib2/default.nix           | 2 +-
 pkgs/development/python-modules/upcloud-api/default.nix       | 2 +-
 pkgs/development/python-modules/uplink/default.nix            | 2 +-
 pkgs/development/python-modules/urllib3-future/default.nix    | 2 +-
 pkgs/development/python-modules/urllib3/default.nix           | 2 +-
 pkgs/development/python-modules/urwid/default.nix             | 2 +-
 pkgs/development/python-modules/validators/default.nix        | 2 +-
 pkgs/development/python-modules/valkey/default.nix            | 2 +-
 pkgs/development/python-modules/visions/default.nix           | 2 +-
 pkgs/development/python-modules/w1thermsensor/default.nix     | 2 +-
 pkgs/development/python-modules/watermark/default.nix         | 2 +-
 pkgs/development/python-modules/werkzeug/default.nix          | 2 +-
 pkgs/development/python-modules/whey/default.nix              | 2 +-
 pkgs/development/python-modules/wtforms/default.nix           | 2 +-
 pkgs/development/python-modules/wyoming/default.nix           | 2 +-
 pkgs/development/python-modules/xarray-einstats/default.nix   | 2 +-
 pkgs/development/python-modules/zeep/default.nix              | 2 +-
 pkgs/development/python-modules/zope-security/default.nix     | 2 +-
 pkgs/tools/security/cve-bin-tool/default.nix                  | 2 +-
 pkgs/top-level/all-packages.nix                               | 2 +-
 281 files changed, 283 insertions(+), 283 deletions(-)

diff --git a/pkgs/applications/networking/instant-messengers/pantalaimon/default.nix b/pkgs/applications/networking/instant-messengers/pantalaimon/default.nix
index 105f579db066..0d249008961f 100644
--- a/pkgs/applications/networking/instant-messengers/pantalaimon/default.nix
+++ b/pkgs/applications/networking/instant-messengers/pantalaimon/default.nix
@@ -65,7 +65,7 @@ python3Packages.buildPythonApplication rec {
       pytest-aiohttp
       pytestCheckHook
     ]
-    ++ lib.flatten (lib.attrValues optional-dependencies);
+    ++ lib.concatAttrValues optional-dependencies;
 
   nativeBuildInputs = lib.optionals enableDbusUi [
     wrapGAppsHook3
diff --git a/pkgs/by-name/al/alpaca/package.nix b/pkgs/by-name/al/alpaca/package.nix
index 508f03ffc0a0..ca26df86d19d 100644
--- a/pkgs/by-name/al/alpaca/package.nix
+++ b/pkgs/by-name/al/alpaca/package.nix
@@ -96,7 +96,7 @@ pythonPackages.buildPythonApplication rec {
       gst-python
       opencv4
     ]
-    ++ lib.flatten (builtins.attrValues optional-dependencies);
+    ++ lib.concatAttrValues optional-dependencies;
 
   optional-dependencies = with pythonPackages; {
     speech-to-text = [
diff --git a/pkgs/by-name/ca/calibre-web/package.nix b/pkgs/by-name/ca/calibre-web/package.nix
index 00bf55796d76..bba0eb9d865e 100644
--- a/pkgs/by-name/ca/calibre-web/package.nix
+++ b/pkgs/by-name/ca/calibre-web/package.nix
@@ -136,7 +136,7 @@ python3Packages.buildPythonApplication rec {
     "unidecode"
   ];
 
-  nativeCheckInputs = lib.flatten (lib.attrValues optional-dependencies);
+  nativeCheckInputs = lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "calibreweb" ];
 
diff --git a/pkgs/by-name/es/esptool/package.nix b/pkgs/by-name/es/esptool/package.nix
index 4b726bd6d9f0..412a00946b52 100644
--- a/pkgs/by-name/es/esptool/package.nix
+++ b/pkgs/by-name/es/esptool/package.nix
@@ -82,7 +82,7 @@ python3Packages.buildPythonApplication rec {
       requests
       softhsm
     ]
-    ++ lib.flatten (lib.attrValues optional-dependencies);
+    ++ lib.concatAttrValues optional-dependencies;
 
   preCheck = ''
     export PATH="$out/bin:$PATH"
diff --git a/pkgs/by-name/ma/matrix-synapse-unwrapped/package.nix b/pkgs/by-name/ma/matrix-synapse-unwrapped/package.nix
index 3017cea5e195..0e86cf4450a8 100644
--- a/pkgs/by-name/ma/matrix-synapse-unwrapped/package.nix
+++ b/pkgs/by-name/ma/matrix-synapse-unwrapped/package.nix
@@ -135,7 +135,7 @@ python3Packages.buildPythonApplication rec {
     mock
     parameterized
   ])
-  ++ lib.filter (pkg: !pkg.meta.broken) (lib.flatten (lib.attrValues optional-dependencies));
+  ++ lib.filter (pkg: !pkg.meta.broken) (lib.concatAttrValues optional-dependencies);
 
   doCheck = !stdenv.hostPlatform.isDarwin;
 
diff --git a/pkgs/by-name/me/mediagoblin/package.nix b/pkgs/by-name/me/mediagoblin/package.nix
index 2add18b3d539..43cc073f3ded 100644
--- a/pkgs/by-name/me/mediagoblin/package.nix
+++ b/pkgs/by-name/me/mediagoblin/package.nix
@@ -163,7 +163,7 @@ python.pkgs.buildPythonApplication rec {
 
       poppler-utils
     ]
-    ++ lib.flatten (lib.attrValues optional-dependencies);
+    ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "mediagoblin" ];
 
diff --git a/pkgs/by-name/me/meerk40t/package.nix b/pkgs/by-name/me/meerk40t/package.nix
index 82ed2e612e6c..ee05c2862b23 100644
--- a/pkgs/by-name/me/meerk40t/package.nix
+++ b/pkgs/by-name/me/meerk40t/package.nix
@@ -40,7 +40,7 @@ python3Packages.buildPythonApplication rec {
       setuptools
       wxpython
     ]
-    ++ lib.flatten (lib.attrValues optional-dependencies);
+    ++ lib.concatAttrValues optional-dependencies;
 
   optional-dependencies = with python3Packages; {
     cam = [
diff --git a/pkgs/by-name/mo/modelscan/package.nix b/pkgs/by-name/mo/modelscan/package.nix
index 1a7b96927377..62a59749f058 100644
--- a/pkgs/by-name/mo/modelscan/package.nix
+++ b/pkgs/by-name/mo/modelscan/package.nix
@@ -41,7 +41,7 @@ python3.pkgs.buildPythonApplication rec {
       dill
       pytestCheckHook
     ]
-    ++ lib.flatten (builtins.attrValues optional-dependencies);
+    ++ lib.concatAttrValues optional-dependencies;
 
   # tensorflow doesn0t support Python 3.12
   doCheck = false;
diff --git a/pkgs/by-name/mu/music-assistant/package.nix b/pkgs/by-name/mu/music-assistant/package.nix
index 396bd10622cb..b30abadac299 100644
--- a/pkgs/by-name/mu/music-assistant/package.nix
+++ b/pkgs/by-name/mu/music-assistant/package.nix
@@ -154,7 +154,7 @@ python.pkgs.buildPythonApplication rec {
       syrupy
       pytest-timeout
     ]
-    ++ lib.flatten (lib.attrValues optional-dependencies)
+    ++ lib.concatAttrValues optional-dependencies
     ++ (providerPackages.jellyfin python.pkgs)
     ++ (providerPackages.opensubsonic python.pkgs);
 
diff --git a/pkgs/by-name/nb/nbqa/package.nix b/pkgs/by-name/nb/nbqa/package.nix
index f9dd52c2f360..2e711ecf7c9b 100644
--- a/pkgs/by-name/nb/nbqa/package.nix
+++ b/pkgs/by-name/nb/nbqa/package.nix
@@ -70,7 +70,7 @@ let
         pytestCheckHook
         yapf
       ])
-      ++ lib.flatten (lib.attrValues optional-dependencies)
+      ++ lib.concatAttrValues optional-dependencies
       ++ [
         addBinToPathHook
         versionCheckHook
diff --git a/pkgs/by-name/pr/pretalx/package.nix b/pkgs/by-name/pr/pretalx/package.nix
index 027b0bd60961..d20227d64687 100644
--- a/pkgs/by-name/pr/pretalx/package.nix
+++ b/pkgs/by-name/pr/pretalx/package.nix
@@ -220,7 +220,7 @@ python.pkgs.buildPythonApplication rec {
       pytestCheckHook
       responses
     ]
-    ++ lib.flatten (lib.attrValues optional-dependencies);
+    ++ lib.concatAttrValues optional-dependencies;
 
   disabledTests = [
     # tries to run npm run i18n:extract
diff --git a/pkgs/by-name/pr/pretix/package.nix b/pkgs/by-name/pr/pretix/package.nix
index 6e4cf62463c7..0287b863ae2b 100644
--- a/pkgs/by-name/pr/pretix/package.nix
+++ b/pkgs/by-name/pr/pretix/package.nix
@@ -256,7 +256,7 @@ python.pkgs.buildPythonApplication rec {
       fakeredis
       responses
     ]
-    ++ lib.flatten (lib.attrValues optional-dependencies);
+    ++ lib.concatAttrValues optional-dependencies;
 
   pytestFlags = [
     "--reruns=3"
diff --git a/pkgs/by-name/py/pyhanko-cli/package.nix b/pkgs/by-name/py/pyhanko-cli/package.nix
index 93c275e08ea0..9b8945f0bb5c 100644
--- a/pkgs/by-name/py/pyhanko-cli/package.nix
+++ b/pkgs/by-name/py/pyhanko-cli/package.nix
@@ -38,7 +38,7 @@ python3Packages.buildPythonApplication rec {
       click
       platformdirs
     ]
-    ++ lib.flatten (lib.attrValues pyhanko.optional-dependencies);
+    ++ lib.concatAttrValues pyhanko.optional-dependencies;
 
   nativeCheckInputs = with python3Packages; [
     pytestCheckHook
diff --git a/pkgs/by-name/yt/yt-dlp/package.nix b/pkgs/by-name/yt/yt-dlp/package.nix
index 977dd7b10ce5..d87ae42abe57 100644
--- a/pkgs/by-name/yt/yt-dlp/package.nix
+++ b/pkgs/by-name/yt/yt-dlp/package.nix
@@ -48,7 +48,7 @@ python3Packages.buildPythonApplication rec {
   ];
 
   # expose optional-dependencies, but provide all features
-  dependencies = lib.flatten (lib.attrValues optional-dependencies);
+  dependencies = lib.concatAttrValues optional-dependencies;
 
   optional-dependencies = {
     default = with python3Packages; [
diff --git a/pkgs/development/python-modules/adb-shell/default.nix b/pkgs/development/python-modules/adb-shell/default.nix
index c62ff7228b50..09f226fd0026 100644
--- a/pkgs/development/python-modules/adb-shell/default.nix
+++ b/pkgs/development/python-modules/adb-shell/default.nix
@@ -50,7 +50,7 @@ buildPythonPackage rec {
     pycryptodome
     pytestCheckHook
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "adb_shell" ];
 
diff --git a/pkgs/development/python-modules/aioboto3/default.nix b/pkgs/development/python-modules/aioboto3/default.nix
index f11a8f308862..5bf77e926d61 100644
--- a/pkgs/development/python-modules/aioboto3/default.nix
+++ b/pkgs/development/python-modules/aioboto3/default.nix
@@ -56,7 +56,7 @@ buildPythonPackage rec {
     pytestCheckHook
   ]
   ++ moto.optional-dependencies.server
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   disabledTests = [
     "test_patches"
diff --git a/pkgs/development/python-modules/aiocache/default.nix b/pkgs/development/python-modules/aiocache/default.nix
index 60352c2de8df..c4af88bf2cbf 100644
--- a/pkgs/development/python-modules/aiocache/default.nix
+++ b/pkgs/development/python-modules/aiocache/default.nix
@@ -47,7 +47,7 @@ buildPythonPackage rec {
     pytestCheckHook
     redisTestHook
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pytestFlags = [
     "-Wignore::DeprecationWarning"
diff --git a/pkgs/development/python-modules/aioftp/default.nix b/pkgs/development/python-modules/aioftp/default.nix
index 2e287cefdf2b..0dd62b68739c 100644
--- a/pkgs/development/python-modules/aioftp/default.nix
+++ b/pkgs/development/python-modules/aioftp/default.nix
@@ -40,7 +40,7 @@ buildPythonPackage rec {
     pytestCheckHook
     trustme
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   disabledTests = lib.optionals stdenv.hostPlatform.isDarwin [
     # uses 127.0.0.2, which macos doesn't like
diff --git a/pkgs/development/python-modules/aiogram/default.nix b/pkgs/development/python-modules/aiogram/default.nix
index ceef494e840b..6db1be8e5a48 100644
--- a/pkgs/development/python-modules/aiogram/default.nix
+++ b/pkgs/development/python-modules/aiogram/default.nix
@@ -77,7 +77,7 @@ buildPythonPackage rec {
     pytestCheckHook
     pytz
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "aiogram" ];
 
diff --git a/pkgs/development/python-modules/aiohomeconnect/default.nix b/pkgs/development/python-modules/aiohomeconnect/default.nix
index 391199f1b664..b3f1b2d1fb51 100644
--- a/pkgs/development/python-modules/aiohomeconnect/default.nix
+++ b/pkgs/development/python-modules/aiohomeconnect/default.nix
@@ -54,7 +54,7 @@ buildPythonPackage rec {
     pytest-httpx
     pytestCheckHook
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "aiohomeconnect" ];
 
diff --git a/pkgs/development/python-modules/aiohttp-client-cache/default.nix b/pkgs/development/python-modules/aiohttp-client-cache/default.nix
index 7356919847e0..6a80eb170645 100644
--- a/pkgs/development/python-modules/aiohttp-client-cache/default.nix
+++ b/pkgs/development/python-modules/aiohttp-client-cache/default.nix
@@ -67,7 +67,7 @@ buildPythonPackage rec {
     pytest-aiohttp
     pytestCheckHook
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pytestFlags = [ "--asyncio-mode=auto" ];
 
diff --git a/pkgs/development/python-modules/aiohttp-fast-zlib/default.nix b/pkgs/development/python-modules/aiohttp-fast-zlib/default.nix
index c09037e69f58..b95c98d4bd28 100644
--- a/pkgs/development/python-modules/aiohttp-fast-zlib/default.nix
+++ b/pkgs/development/python-modules/aiohttp-fast-zlib/default.nix
@@ -34,7 +34,7 @@ buildPythonPackage rec {
     zlib_ng = [ zlib-ng ];
   };
 
-  nativeCheckInputs = [ pytestCheckHook ] ++ lib.flatten (lib.attrValues optional-dependencies);
+  nativeCheckInputs = [ pytestCheckHook ] ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "aiohttp_fast_zlib" ];
 
diff --git a/pkgs/development/python-modules/aiojobs/default.nix b/pkgs/development/python-modules/aiojobs/default.nix
index bdfdf0c16571..321d70bbd61b 100644
--- a/pkgs/development/python-modules/aiojobs/default.nix
+++ b/pkgs/development/python-modules/aiojobs/default.nix
@@ -38,7 +38,7 @@ buildPythonPackage rec {
     pytest-aiohttp
     pytest-cov-stub
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "aiojobs" ];
 
diff --git a/pkgs/development/python-modules/aiomisc/default.nix b/pkgs/development/python-modules/aiomisc/default.nix
index f34541fad92f..7b2efe7507d3 100644
--- a/pkgs/development/python-modules/aiomisc/default.nix
+++ b/pkgs/development/python-modules/aiomisc/default.nix
@@ -42,7 +42,7 @@ buildPythonPackage rec {
     pytestCheckHook
     setproctitle
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   optional-dependencies = {
     aiohttp = [ aiohttp ];
diff --git a/pkgs/development/python-modules/aioprometheus/default.nix b/pkgs/development/python-modules/aioprometheus/default.nix
index d1d429e484eb..930ab1bbf080 100644
--- a/pkgs/development/python-modules/aioprometheus/default.nix
+++ b/pkgs/development/python-modules/aioprometheus/default.nix
@@ -47,7 +47,7 @@ buildPythonPackage rec {
     fastapi
     uvicorn
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "aioprometheus" ];
 
diff --git a/pkgs/development/python-modules/aiorpcx/default.nix b/pkgs/development/python-modules/aiorpcx/default.nix
index c217cdfe6f3b..a6b04230c5ba 100644
--- a/pkgs/development/python-modules/aiorpcx/default.nix
+++ b/pkgs/development/python-modules/aiorpcx/default.nix
@@ -28,7 +28,7 @@ buildPythonPackage rec {
     pytest-asyncio_0
     pytestCheckHook
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   disabledTests = [
     # network access
diff --git a/pkgs/development/python-modules/aiortm/default.nix b/pkgs/development/python-modules/aiortm/default.nix
index a55633c9f229..2df8d7df31ad 100644
--- a/pkgs/development/python-modules/aiortm/default.nix
+++ b/pkgs/development/python-modules/aiortm/default.nix
@@ -50,7 +50,7 @@ buildPythonPackage rec {
     pytest-cov-stub
     pytestCheckHook
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "aiortm" ];
 
diff --git a/pkgs/development/python-modules/aiovlc/default.nix b/pkgs/development/python-modules/aiovlc/default.nix
index 5f91b6c75d26..b954f6792f73 100644
--- a/pkgs/development/python-modules/aiovlc/default.nix
+++ b/pkgs/development/python-modules/aiovlc/default.nix
@@ -37,7 +37,7 @@ buildPythonPackage rec {
     pytest-timeout
     pytestCheckHook
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "aiovlc" ];
 
diff --git a/pkgs/development/python-modules/alpha-vantage/default.nix b/pkgs/development/python-modules/alpha-vantage/default.nix
index 8225ce7ca654..e8071644058b 100644
--- a/pkgs/development/python-modules/alpha-vantage/default.nix
+++ b/pkgs/development/python-modules/alpha-vantage/default.nix
@@ -50,7 +50,7 @@ buildPythonPackage rec {
     requests-mock
     pytestCheckHook
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   # Starting with 3.0.0 most tests require an API key
   doCheck = false;
diff --git a/pkgs/development/python-modules/apischema/default.nix b/pkgs/development/python-modules/apischema/default.nix
index b470b3454d8c..633e10805283 100644
--- a/pkgs/development/python-modules/apischema/default.nix
+++ b/pkgs/development/python-modules/apischema/default.nix
@@ -39,7 +39,7 @@ buildPythonPackage rec {
     pytest-asyncio
     pytest8_3CheckHook
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "apischema" ];
 
diff --git a/pkgs/development/python-modules/apispec/default.nix b/pkgs/development/python-modules/apispec/default.nix
index 7d6e14079f73..fc47c87d7f98 100644
--- a/pkgs/development/python-modules/apispec/default.nix
+++ b/pkgs/development/python-modules/apispec/default.nix
@@ -43,7 +43,7 @@ buildPythonPackage rec {
     mock
     pytestCheckHook
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "apispec" ];
 
diff --git a/pkgs/development/python-modules/apptools/default.nix b/pkgs/development/python-modules/apptools/default.nix
index 1abfe191134c..ff9a12ce32ed 100644
--- a/pkgs/development/python-modules/apptools/default.nix
+++ b/pkgs/development/python-modules/apptools/default.nix
@@ -46,7 +46,7 @@ buildPythonPackage rec {
     preferences = [ configobj ];
   };
 
-  nativeCheckInputs = [ pytestCheckHook ] ++ lib.flatten (lib.attrValues optional-dependencies);
+  nativeCheckInputs = [ pytestCheckHook ] ++ lib.concatAttrValues optional-dependencies;
 
   preCheck = ''
     export HOME=$TMP
diff --git a/pkgs/development/python-modules/arelle/default.nix b/pkgs/development/python-modules/arelle/default.nix
index 9654ad7f97c4..1f78aed68688 100644
--- a/pkgs/development/python-modules/arelle/default.nix
+++ b/pkgs/development/python-modules/arelle/default.nix
@@ -143,7 +143,7 @@ buildPythonPackage rec {
     pytestCheckHook
     boto3
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   disabledTestPaths = [
     "tests/integration_tests"
diff --git a/pkgs/development/python-modules/argilla/default.nix b/pkgs/development/python-modules/argilla/default.nix
index cc036c8c036c..7d7a1c73c02a 100644
--- a/pkgs/development/python-modules/argilla/default.nix
+++ b/pkgs/development/python-modules/argilla/default.nix
@@ -181,7 +181,7 @@ buildPythonPackage rec {
     pytest-asyncio
     factory-boy
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   disabledTestPaths = [ "tests/server/datasets/test_dao.py" ];
 
diff --git a/pkgs/development/python-modules/asn1tools/default.nix b/pkgs/development/python-modules/asn1tools/default.nix
index f03d39d05379..f5e1cac08acb 100644
--- a/pkgs/development/python-modules/asn1tools/default.nix
+++ b/pkgs/development/python-modules/asn1tools/default.nix
@@ -49,7 +49,7 @@ buildPythonPackage rec {
     pytestCheckHook
     versionCheckHook
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
   versionCheckProgramArg = "--version";
 
   pythonImportsCheck = [ "asn1tools" ];
diff --git a/pkgs/development/python-modules/asyncssh/default.nix b/pkgs/development/python-modules/asyncssh/default.nix
index 57566cfb675c..b2bd21365dfe 100644
--- a/pkgs/development/python-modules/asyncssh/default.nix
+++ b/pkgs/development/python-modules/asyncssh/default.nix
@@ -57,7 +57,7 @@ buildPythonPackage rec {
     openssl
     pytestCheckHook
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   patches = [
     # Reverts https://github.com/ronf/asyncssh/commit/4b3dec994b3aa821dba4db507030b569c3a32730
diff --git a/pkgs/development/python-modules/avwx-engine/default.nix b/pkgs/development/python-modules/avwx-engine/default.nix
index 781362fc6503..a0bd074e9294 100644
--- a/pkgs/development/python-modules/avwx-engine/default.nix
+++ b/pkgs/development/python-modules/avwx-engine/default.nix
@@ -59,7 +59,7 @@ buildPythonPackage rec {
     pytestCheckHook
     time-machine
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "avwx" ];
 
diff --git a/pkgs/development/python-modules/azure-core/default.nix b/pkgs/development/python-modules/azure-core/default.nix
index 4f4e81311ed0..7513c365d737 100644
--- a/pkgs/development/python-modules/azure-core/default.nix
+++ b/pkgs/development/python-modules/azure-core/default.nix
@@ -64,7 +64,7 @@ buildPythonPackage rec {
     pytestCheckHook
     trio
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   # test server needs to be available
   preCheck = ''
diff --git a/pkgs/development/python-modules/azure-kusto-data/default.nix b/pkgs/development/python-modules/azure-kusto-data/default.nix
index 5fa85ce9827d..dc2697774353 100644
--- a/pkgs/development/python-modules/azure-kusto-data/default.nix
+++ b/pkgs/development/python-modules/azure-kusto-data/default.nix
@@ -56,7 +56,7 @@ buildPythonPackage rec {
     pytest-asyncio
     pytestCheckHook
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "azure.kusto.data" ];
 
diff --git a/pkgs/development/python-modules/azure-kusto-ingest/default.nix b/pkgs/development/python-modules/azure-kusto-ingest/default.nix
index c59e9a57eb39..e648edd2fa9d 100644
--- a/pkgs/development/python-modules/azure-kusto-ingest/default.nix
+++ b/pkgs/development/python-modules/azure-kusto-ingest/default.nix
@@ -55,7 +55,7 @@ buildPythonPackage rec {
     pytestCheckHook
     responses
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "azure.kusto.ingest" ];
 
diff --git a/pkgs/development/python-modules/banks/default.nix b/pkgs/development/python-modules/banks/default.nix
index d002be189ec9..83db9ac6b498 100644
--- a/pkgs/development/python-modules/banks/default.nix
+++ b/pkgs/development/python-modules/banks/default.nix
@@ -52,7 +52,7 @@ buildPythonPackage rec {
     pytest-asyncio
     pytestCheckHook
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "banks" ];
 
diff --git a/pkgs/development/python-modules/basedmypy/default.nix b/pkgs/development/python-modules/basedmypy/default.nix
index 0ffba2cfe3a5..f71c4c195fc8 100644
--- a/pkgs/development/python-modules/basedmypy/default.nix
+++ b/pkgs/development/python-modules/basedmypy/default.nix
@@ -104,7 +104,7 @@ buildPythonPackage rec {
     setuptools
     tomli
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   disabledTests = lib.optionals (pythonAtLeast "3.12") [
     # cannot find distutils, and distutils cannot find types
diff --git a/pkgs/development/python-modules/bc-detect-secrets/default.nix b/pkgs/development/python-modules/bc-detect-secrets/default.nix
index bf6a2f864b5f..6f82d3c805d3 100644
--- a/pkgs/development/python-modules/bc-detect-secrets/default.nix
+++ b/pkgs/development/python-modules/bc-detect-secrets/default.nix
@@ -50,7 +50,7 @@ buildPythonPackage rec {
     responses
     writableTmpDirAsHomeHook
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   disabledTests = [
     # Tests are failing for various reasons (missing git repo, missing test data, etc.)
diff --git a/pkgs/development/python-modules/beanhub-cli/default.nix b/pkgs/development/python-modules/beanhub-cli/default.nix
index 5b814c7023c8..1fff5fbcbf64 100644
--- a/pkgs/development/python-modules/beanhub-cli/default.nix
+++ b/pkgs/development/python-modules/beanhub-cli/default.nix
@@ -72,7 +72,7 @@ buildPythonPackage rec {
     starlette-wtf
     uvicorn
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   optional-dependencies = {
     login = [
@@ -100,7 +100,7 @@ buildPythonPackage rec {
     pytest-mock
     pytestCheckHook
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "beanhub_cli" ];
 
diff --git a/pkgs/development/python-modules/beautifulsoup4/default.nix b/pkgs/development/python-modules/beautifulsoup4/default.nix
index 47d807412197..a82044e74eea 100644
--- a/pkgs/development/python-modules/beautifulsoup4/default.nix
+++ b/pkgs/development/python-modules/beautifulsoup4/default.nix
@@ -77,7 +77,7 @@ buildPythonPackage rec {
   nativeCheckInputs = [
     pytestCheckHook
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   disabledTests = [
     # fail with latest libxml, by not actually rejecting
diff --git a/pkgs/development/python-modules/betterproto/default.nix b/pkgs/development/python-modules/betterproto/default.nix
index ef4839a39ec3..53df463ec585 100644
--- a/pkgs/development/python-modules/betterproto/default.nix
+++ b/pkgs/development/python-modules/betterproto/default.nix
@@ -59,7 +59,7 @@ buildPythonPackage rec {
     pytestCheckHook
     tomlkit
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "betterproto" ];
 
diff --git a/pkgs/development/python-modules/bimmer-connected/default.nix b/pkgs/development/python-modules/bimmer-connected/default.nix
index d6be72425424..9bd324394aaf 100644
--- a/pkgs/development/python-modules/bimmer-connected/default.nix
+++ b/pkgs/development/python-modules/bimmer-connected/default.nix
@@ -58,7 +58,7 @@ buildPythonPackage rec {
     respx
     time-machine
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   disabledTests = [
     # presumably regressed in pytest-asyncio 0.23.0
diff --git a/pkgs/development/python-modules/black/default.nix b/pkgs/development/python-modules/black/default.nix
index 70fac527e59e..8cab13d38ac0 100644
--- a/pkgs/development/python-modules/black/default.nix
+++ b/pkgs/development/python-modules/black/default.nix
@@ -90,7 +90,7 @@ buildPythonPackage rec {
     pytestCheckHook
     parameterized
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pytestFlags = [
     "-Wignore::DeprecationWarning"
diff --git a/pkgs/development/python-modules/bpython/default.nix b/pkgs/development/python-modules/bpython/default.nix
index 68798c64e1ed..f6e22a704a62 100644
--- a/pkgs/development/python-modules/bpython/default.nix
+++ b/pkgs/development/python-modules/bpython/default.nix
@@ -60,7 +60,7 @@ buildPythonPackage rec {
   nativeCheckInputs = [
     pytestCheckHook
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "bpython" ];
 
diff --git a/pkgs/development/python-modules/busylight-for-humans/default.nix b/pkgs/development/python-modules/busylight-for-humans/default.nix
index 4f43864ea06f..b0018008f1f7 100644
--- a/pkgs/development/python-modules/busylight-for-humans/default.nix
+++ b/pkgs/development/python-modules/busylight-for-humans/default.nix
@@ -55,7 +55,7 @@ buildPythonPackage rec {
     pytest-mock
     udevCheckHook
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   disabledTestPaths = [ "tests/test_pydantic_models.py" ];
 
diff --git a/pkgs/development/python-modules/bytewax/default.nix b/pkgs/development/python-modules/bytewax/default.nix
index ac39958242fb..fe984f43063c 100644
--- a/pkgs/development/python-modules/bytewax/default.nix
+++ b/pkgs/development/python-modules/bytewax/default.nix
@@ -84,7 +84,7 @@ buildPythonPackage rec {
     pytestCheckHook
     pytest-benchmark
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pytestFlags = [
     "--benchmark-disable"
diff --git a/pkgs/development/python-modules/cachecontrol/default.nix b/pkgs/development/python-modules/cachecontrol/default.nix
index cc614b5d954f..5872bd68c6a9 100644
--- a/pkgs/development/python-modules/cachecontrol/default.nix
+++ b/pkgs/development/python-modules/cachecontrol/default.nix
@@ -41,7 +41,7 @@ buildPythonPackage rec {
     cherrypy
     pytestCheckHook
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "cachecontrol" ];
 
diff --git a/pkgs/development/python-modules/canals/default.nix b/pkgs/development/python-modules/canals/default.nix
index 2864939e54ec..fc7a32dc0fb4 100644
--- a/pkgs/development/python-modules/canals/default.nix
+++ b/pkgs/development/python-modules/canals/default.nix
@@ -46,7 +46,7 @@ buildPythonPackage rec {
   nativeCheckInputs = [
     pytestCheckHook
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   disabledTestPaths = [
     # Test requires internet connection to mermaid.ink
diff --git a/pkgs/development/python-modules/canmatrix/default.nix b/pkgs/development/python-modules/canmatrix/default.nix
index cf08abf5766c..94195acf6388 100644
--- a/pkgs/development/python-modules/canmatrix/default.nix
+++ b/pkgs/development/python-modules/canmatrix/default.nix
@@ -57,7 +57,7 @@ buildPythonPackage rec {
     pytest-timeout
     pytestCheckHook
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pytestFlags = [
     # long_envvar_name_imports requires stable key value pair ordering
diff --git a/pkgs/development/python-modules/cartopy/default.nix b/pkgs/development/python-modules/cartopy/default.nix
index 9572ec1ab0b9..71791845c795 100644
--- a/pkgs/development/python-modules/cartopy/default.nix
+++ b/pkgs/development/python-modules/cartopy/default.nix
@@ -70,7 +70,7 @@ buildPythonPackage rec {
     pytest-mpl
     pytestCheckHook
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   preCheck = ''
     export FONTCONFIG_FILE=${fontconfig.out}/etc/fonts/fonts.conf
diff --git a/pkgs/development/python-modules/cassandra-driver/default.nix b/pkgs/development/python-modules/cassandra-driver/default.nix
index 7aefe2844a36..667b9cdde15f 100644
--- a/pkgs/development/python-modules/cassandra-driver/default.nix
+++ b/pkgs/development/python-modules/cassandra-driver/default.nix
@@ -66,7 +66,7 @@ buildPythonPackage rec {
     pyyaml
     sure
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   # This is used to determine the version of cython that can be used
   CASS_DRIVER_ALLOWED_CYTHON_VERSION = cython.version;
diff --git a/pkgs/development/python-modules/catppuccin/default.nix b/pkgs/development/python-modules/catppuccin/default.nix
index 84b5be78fc3f..2e588e3bbb8a 100644
--- a/pkgs/development/python-modules/catppuccin/default.nix
+++ b/pkgs/development/python-modules/catppuccin/default.nix
@@ -30,7 +30,7 @@ buildPythonPackage rec {
     rich = [ rich ];
   };
 
-  nativeCheckInputs = [ pytestCheckHook ] ++ lib.flatten (lib.attrValues optional-dependencies);
+  nativeCheckInputs = [ pytestCheckHook ] ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "catppuccin" ];
 
diff --git a/pkgs/development/python-modules/celery/default.nix b/pkgs/development/python-modules/celery/default.nix
index afd13b3844d2..ab0889594166 100644
--- a/pkgs/development/python-modules/celery/default.nix
+++ b/pkgs/development/python-modules/celery/default.nix
@@ -93,7 +93,7 @@ buildPythonPackage rec {
     pytest-xdist
     pytestCheckHook
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   disabledTestPaths = [
     # test_eventlet touches network
diff --git a/pkgs/development/python-modules/cement/default.nix b/pkgs/development/python-modules/cement/default.nix
index 864fc2df9c8d..972df6c10802 100644
--- a/pkgs/development/python-modules/cement/default.nix
+++ b/pkgs/development/python-modules/cement/default.nix
@@ -57,7 +57,7 @@ buildPythonPackage rec {
     pytestCheckHook
     requests
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "cement" ];
 
diff --git a/pkgs/development/python-modules/certomancer/default.nix b/pkgs/development/python-modules/certomancer/default.nix
index 6022ed98849f..52fc8038bbbc 100644
--- a/pkgs/development/python-modules/certomancer/default.nix
+++ b/pkgs/development/python-modules/certomancer/default.nix
@@ -72,7 +72,7 @@ buildPythonPackage rec {
     pytz
     requests
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "certomancer" ];
 
diff --git a/pkgs/development/python-modules/cf-xarray/default.nix b/pkgs/development/python-modules/cf-xarray/default.nix
index 1ca3d047413b..d7d5638c63e3 100644
--- a/pkgs/development/python-modules/cf-xarray/default.nix
+++ b/pkgs/development/python-modules/cf-xarray/default.nix
@@ -58,7 +58,7 @@ buildPythonPackage rec {
     pytestCheckHook
     scipy
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "cf_xarray" ];
 
diff --git a/pkgs/development/python-modules/cfn-lint/default.nix b/pkgs/development/python-modules/cfn-lint/default.nix
index 49345a232132..3b61fba76186 100644
--- a/pkgs/development/python-modules/cfn-lint/default.nix
+++ b/pkgs/development/python-modules/cfn-lint/default.nix
@@ -70,7 +70,7 @@ buildPythonPackage rec {
     mock
     pytestCheckHook
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   preCheck = ''
     export PATH=$out/bin:$PATH
diff --git a/pkgs/development/python-modules/channels/default.nix b/pkgs/development/python-modules/channels/default.nix
index efa8886f633b..0de401636e2b 100644
--- a/pkgs/development/python-modules/channels/default.nix
+++ b/pkgs/development/python-modules/channels/default.nix
@@ -41,7 +41,7 @@ buildPythonPackage rec {
     pytest-django
     pytestCheckHook
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   # won't run in sandbox
   disabledTestPaths = [
diff --git a/pkgs/development/python-modules/cli-helpers/default.nix b/pkgs/development/python-modules/cli-helpers/default.nix
index fdd1962b5c87..f9070cad7384 100644
--- a/pkgs/development/python-modules/cli-helpers/default.nix
+++ b/pkgs/development/python-modules/cli-helpers/default.nix
@@ -37,7 +37,7 @@ buildPythonPackage rec {
     pytestCheckHook
     mock
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   meta = with lib; {
     description = "Python helpers for common CLI tasks";
diff --git a/pkgs/development/python-modules/coinmetrics-api-client/default.nix b/pkgs/development/python-modules/coinmetrics-api-client/default.nix
index 61380e80a8ff..4f4caf6be44b 100644
--- a/pkgs/development/python-modules/coinmetrics-api-client/default.nix
+++ b/pkgs/development/python-modules/coinmetrics-api-client/default.nix
@@ -52,7 +52,7 @@ buildPythonPackage rec {
     pytestCheckHook
     pytest-mock
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "coinmetrics.api_client" ];
 
diff --git a/pkgs/development/python-modules/comicapi/default.nix b/pkgs/development/python-modules/comicapi/default.nix
index c7eebd06542a..d9b41abee266 100644
--- a/pkgs/development/python-modules/comicapi/default.nix
+++ b/pkgs/development/python-modules/comicapi/default.nix
@@ -64,7 +64,7 @@ buildPythonPackage rec {
     icu = lib.optional (stdenv.hostPlatform.isDarwin || stdenv.hostPlatform.isLinux) pyicu;
   };
 
-  nativeCheckInputs = [ pytestCheckHook ] ++ lib.flatten (lib.attrValues optional-dependencies);
+  nativeCheckInputs = [ pytestCheckHook ] ++ lib.concatAttrValues optional-dependencies;
 
   pythonRelaxDeps = [ "pycountry" ];
 
diff --git a/pkgs/development/python-modules/configargparse/default.nix b/pkgs/development/python-modules/configargparse/default.nix
index aa6531fdb91e..d835924a0750 100644
--- a/pkgs/development/python-modules/configargparse/default.nix
+++ b/pkgs/development/python-modules/configargparse/default.nix
@@ -31,7 +31,7 @@ buildPythonPackage rec {
     pytestCheckHook
     mock
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   disabledTests = lib.optionals (pythonAtLeast "3.13") [
     # regex mismatch
diff --git a/pkgs/development/python-modules/confluent-kafka/default.nix b/pkgs/development/python-modules/confluent-kafka/default.nix
index 0aeb5535f799..d73a38ce94b0 100644
--- a/pkgs/development/python-modules/confluent-kafka/default.nix
+++ b/pkgs/development/python-modules/confluent-kafka/default.nix
@@ -94,7 +94,7 @@ buildPythonPackage rec {
     requests-mock
     respx
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "confluent_kafka" ];
 
diff --git a/pkgs/development/python-modules/connexion/default.nix b/pkgs/development/python-modules/connexion/default.nix
index ff6280e4ea08..56667b26f7e5 100644
--- a/pkgs/development/python-modules/connexion/default.nix
+++ b/pkgs/development/python-modules/connexion/default.nix
@@ -74,7 +74,7 @@ buildPythonPackage rec {
     pytestCheckHook
     testfixtures
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "connexion" ];
 
diff --git a/pkgs/development/python-modules/construct/default.nix b/pkgs/development/python-modules/construct/default.nix
index 98bc1d47d66e..8accaee36821 100644
--- a/pkgs/development/python-modules/construct/default.nix
+++ b/pkgs/development/python-modules/construct/default.nix
@@ -48,7 +48,7 @@ buildPythonPackage rec {
   nativeCheckInputs = [
     pytestCheckHook
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "construct" ];
 
diff --git a/pkgs/development/python-modules/control/default.nix b/pkgs/development/python-modules/control/default.nix
index 4f766f00fcbd..31c77c2d3291 100644
--- a/pkgs/development/python-modules/control/default.nix
+++ b/pkgs/development/python-modules/control/default.nix
@@ -47,7 +47,7 @@ buildPythonPackage rec {
     pytest-timeout
     pytestCheckHook
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "control" ];
 
diff --git a/pkgs/development/python-modules/cyclonedx-python-lib/default.nix b/pkgs/development/python-modules/cyclonedx-python-lib/default.nix
index 277f0afd13cb..862271e58341 100644
--- a/pkgs/development/python-modules/cyclonedx-python-lib/default.nix
+++ b/pkgs/development/python-modules/cyclonedx-python-lib/default.nix
@@ -67,7 +67,7 @@ buildPythonPackage rec {
     pytestCheckHook
     xmldiff
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "cyclonedx" ];
 
diff --git a/pkgs/development/python-modules/cyclopts/default.nix b/pkgs/development/python-modules/cyclopts/default.nix
index 608a8006dfd7..8ec740d9d6a2 100644
--- a/pkgs/development/python-modules/cyclopts/default.nix
+++ b/pkgs/development/python-modules/cyclopts/default.nix
@@ -49,7 +49,7 @@ buildPythonPackage rec {
     pytest-mock
     pytestCheckHook
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "cyclopts" ];
 
diff --git a/pkgs/development/python-modules/dask-awkward/default.nix b/pkgs/development/python-modules/dask-awkward/default.nix
index 28c9fd9be2de..15accd1fb914 100644
--- a/pkgs/development/python-modules/dask-awkward/default.nix
+++ b/pkgs/development/python-modules/dask-awkward/default.nix
@@ -60,7 +60,7 @@ buildPythonPackage rec {
     pytestCheckHook
     uproot
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "dask_awkward" ];
 
diff --git a/pkgs/development/python-modules/dataclass-wizard/default.nix b/pkgs/development/python-modules/dataclass-wizard/default.nix
index 570aa2e304c7..24ff8142cc3d 100644
--- a/pkgs/development/python-modules/dataclass-wizard/default.nix
+++ b/pkgs/development/python-modules/dataclass-wizard/default.nix
@@ -41,7 +41,7 @@ buildPythonPackage rec {
     pytestCheckHook
     pytest-mock
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   disabledTests =
     [ ]
diff --git a/pkgs/development/python-modules/datamodel-code-generator/default.nix b/pkgs/development/python-modules/datamodel-code-generator/default.nix
index cd31504f1ae6..7fed821d24f6 100644
--- a/pkgs/development/python-modules/datamodel-code-generator/default.nix
+++ b/pkgs/development/python-modules/datamodel-code-generator/default.nix
@@ -76,7 +76,7 @@ buildPythonPackage rec {
     pytest-mock
     pytestCheckHook
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "datamodel_code_generator" ];
 
diff --git a/pkgs/development/python-modules/dateparser/default.nix b/pkgs/development/python-modules/dateparser/default.nix
index a874c2575860..7fa8566caa50 100644
--- a/pkgs/development/python-modules/dateparser/default.nix
+++ b/pkgs/development/python-modules/dateparser/default.nix
@@ -61,7 +61,7 @@ buildPythonPackage rec {
     requests
     ruamel-yaml
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   preCheck = ''
     export HOME="$TEMPDIR"
diff --git a/pkgs/development/python-modules/deepdiff/default.nix b/pkgs/development/python-modules/deepdiff/default.nix
index 94428d5daa3b..0c0478fc751c 100644
--- a/pkgs/development/python-modules/deepdiff/default.nix
+++ b/pkgs/development/python-modules/deepdiff/default.nix
@@ -68,7 +68,7 @@ buildPythonPackage rec {
     pandas
     uuid6
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   disabledTests = [
     # Require pytest-benchmark
diff --git a/pkgs/development/python-modules/dependency-injector/default.nix b/pkgs/development/python-modules/dependency-injector/default.nix
index 54154d299104..e5e0213cb6c7 100644
--- a/pkgs/development/python-modules/dependency-injector/default.nix
+++ b/pkgs/development/python-modules/dependency-injector/default.nix
@@ -49,7 +49,7 @@ buildPythonPackage rec {
     pytestCheckHook
     scipy
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "dependency_injector" ];
 
diff --git a/pkgs/development/python-modules/diffusers/default.nix b/pkgs/development/python-modules/diffusers/default.nix
index 700b044af452..d72e188c70b3 100644
--- a/pkgs/development/python-modules/diffusers/default.nix
+++ b/pkgs/development/python-modules/diffusers/default.nix
@@ -104,7 +104,7 @@ buildPythonPackage rec {
     torchsde
     transformers
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   preCheck =
     let
diff --git a/pkgs/development/python-modules/dissect-cobaltstrike/default.nix b/pkgs/development/python-modules/dissect-cobaltstrike/default.nix
index 4c8bdc38dfae..c2013888033b 100644
--- a/pkgs/development/python-modules/dissect-cobaltstrike/default.nix
+++ b/pkgs/development/python-modules/dissect-cobaltstrike/default.nix
@@ -69,7 +69,7 @@ buildPythonPackage rec {
     pytest-httpserver
     pytestCheckHook
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "dissect.cobaltstrike" ];
 
diff --git a/pkgs/development/python-modules/django-allauth/default.nix b/pkgs/development/python-modules/django-allauth/default.nix
index 62fee3d42d39..11c4227e4f3c 100644
--- a/pkgs/development/python-modules/django-allauth/default.nix
+++ b/pkgs/development/python-modules/django-allauth/default.nix
@@ -102,7 +102,7 @@ buildPythonPackage rec {
     pytestCheckHook
     pyyaml
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   disabledTests = [
     # Tests require network access
diff --git a/pkgs/development/python-modules/django-bootstrap5/default.nix b/pkgs/development/python-modules/django-bootstrap5/default.nix
index 538d2adc202e..8d9229ac9bb4 100644
--- a/pkgs/development/python-modules/django-bootstrap5/default.nix
+++ b/pkgs/development/python-modules/django-bootstrap5/default.nix
@@ -47,7 +47,7 @@ buildPythonPackage rec {
     pytest-django
     pytestCheckHook
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   preCheck = ''
     export DJANGO_SETTINGS_MODULE=tests.app.settings
diff --git a/pkgs/development/python-modules/django-import-export/default.nix b/pkgs/development/python-modules/django-import-export/default.nix
index 0c4e0ec27937..80c4a1c27fd2 100644
--- a/pkgs/development/python-modules/django-import-export/default.nix
+++ b/pkgs/development/python-modules/django-import-export/default.nix
@@ -49,7 +49,7 @@ buildPythonPackage rec {
     psycopg2
     pytz
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   checkPhase = ''
     runHook preCheck
diff --git a/pkgs/development/python-modules/django-redis/default.nix b/pkgs/development/python-modules/django-redis/default.nix
index c50ecf553d7f..681921f5be3e 100644
--- a/pkgs/development/python-modules/django-redis/default.nix
+++ b/pkgs/development/python-modules/django-redis/default.nix
@@ -63,7 +63,7 @@ buildPythonPackage rec {
     pytestCheckHook
     redisTestHook
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   # https://github.com/jazzband/django-redis/issues/777
   dontUsePytestXdist = true;
diff --git a/pkgs/development/python-modules/django-storages/default.nix b/pkgs/development/python-modules/django-storages/default.nix
index b30ada9f6cec..e3d35b8ec0dc 100644
--- a/pkgs/development/python-modules/django-storages/default.nix
+++ b/pkgs/development/python-modules/django-storages/default.nix
@@ -63,7 +63,7 @@ buildPythonPackage rec {
     pytestCheckHook
     rsa
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   checkInputs = [ pynacl ];
 
diff --git a/pkgs/development/python-modules/django-stubs/default.nix b/pkgs/development/python-modules/django-stubs/default.nix
index 77e65134666e..f3fcced7acb3 100644
--- a/pkgs/development/python-modules/django-stubs/default.nix
+++ b/pkgs/development/python-modules/django-stubs/default.nix
@@ -54,7 +54,7 @@ buildPythonPackage rec {
     pytest-mypy-plugins
     pytestCheckHook
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   disabledTests = [
     # AttributeError: module 'django.contrib.auth.forms' has no attribute 'SetUnusablePasswordMixin'
diff --git a/pkgs/development/python-modules/django-tables2/default.nix b/pkgs/development/python-modules/django-tables2/default.nix
index 54c1082c4aba..72f43d6e6482 100644
--- a/pkgs/development/python-modules/django-tables2/default.nix
+++ b/pkgs/development/python-modules/django-tables2/default.nix
@@ -53,7 +53,7 @@ buildPythonPackage rec {
     pytest-django
     pytestCheckHook
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   meta = with lib; {
     changelog = "https://github.com/jieter/django-tables2/blob/v${version}/CHANGELOG.md";
diff --git a/pkgs/development/python-modules/django/4.nix b/pkgs/development/python-modules/django/4.nix
index 570ee2e03b8b..6ec59f663502 100644
--- a/pkgs/development/python-modules/django/4.nix
+++ b/pkgs/development/python-modules/django/4.nix
@@ -137,7 +137,7 @@ buildPythonPackage rec {
     tblib
     tzdata
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   doCheck =
     !stdenv.hostPlatform.isDarwin
diff --git a/pkgs/development/python-modules/django/5_1.nix b/pkgs/development/python-modules/django/5_1.nix
index 39f2df19b603..87f5fa371a59 100644
--- a/pkgs/development/python-modules/django/5_1.nix
+++ b/pkgs/development/python-modules/django/5_1.nix
@@ -114,7 +114,7 @@ buildPythonPackage rec {
     tblib
     tzdata
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   preCheck = ''
     # make sure the installed library gets imported
diff --git a/pkgs/development/python-modules/django/5_2.nix b/pkgs/development/python-modules/django/5_2.nix
index 52a828a21e09..9245e6fb1445 100644
--- a/pkgs/development/python-modules/django/5_2.nix
+++ b/pkgs/development/python-modules/django/5_2.nix
@@ -106,7 +106,7 @@ buildPythonPackage rec {
     tblib
     tzdata
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   preCheck = ''
     # make sure the installed library gets imported
diff --git a/pkgs/development/python-modules/djangorestframework-stubs/default.nix b/pkgs/development/python-modules/djangorestframework-stubs/default.nix
index e0be6cd948bc..27cd452e373c 100644
--- a/pkgs/development/python-modules/djangorestframework-stubs/default.nix
+++ b/pkgs/development/python-modules/djangorestframework-stubs/default.nix
@@ -57,7 +57,7 @@ buildPythonPackage rec {
     pytest-mypy-plugins
     pytestCheckHook
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   # Upstream recommends mypy > 1.7 which we don't have yet, thus all tests are failing with 3.14.5 and below
   doCheck = false;
diff --git a/pkgs/development/python-modules/docker/default.nix b/pkgs/development/python-modules/docker/default.nix
index 3f37e8a6b102..e848f3f1cdc4 100644
--- a/pkgs/development/python-modules/docker/default.nix
+++ b/pkgs/development/python-modules/docker/default.nix
@@ -58,7 +58,7 @@ buildPythonPackage rec {
   nativeCheckInputs = [
     pytestCheckHook
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   enabledTestPaths = [ "tests/unit" ];
 
diff --git a/pkgs/development/python-modules/dockerflow/default.nix b/pkgs/development/python-modules/dockerflow/default.nix
index 5e8efff7d224..0567f69ceaf5 100644
--- a/pkgs/development/python-modules/dockerflow/default.nix
+++ b/pkgs/development/python-modules/dockerflow/default.nix
@@ -74,7 +74,7 @@ buildPythonPackage rec {
     # fastapi
     httpx
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   disabledTests = [
     # AssertionError: assert 'c7a05e2b-8a21-4255-a3ed-92cea1e74a62' is None
diff --git a/pkgs/development/python-modules/dparse/default.nix b/pkgs/development/python-modules/dparse/default.nix
index 6c4ebf37ac13..d1e3cabd97b1 100644
--- a/pkgs/development/python-modules/dparse/default.nix
+++ b/pkgs/development/python-modules/dparse/default.nix
@@ -36,7 +36,7 @@ buildPythonPackage rec {
   nativeCheckInputs = [
     pytestCheckHook
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "dparse" ];
 
diff --git a/pkgs/development/python-modules/dramatiq-abort/default.nix b/pkgs/development/python-modules/dramatiq-abort/default.nix
index 655d2da4ec0f..b9a0d88c7086 100644
--- a/pkgs/development/python-modules/dramatiq-abort/default.nix
+++ b/pkgs/development/python-modules/dramatiq-abort/default.nix
@@ -29,7 +29,7 @@ buildPythonPackage rec {
   ];
 
   optional-dependencies = {
-    all = lib.flatten (lib.attrValues (lib.removeAttrs optional-dependencies [ "all" ]));
+    all = lib.concatAttrValues (lib.removeAttrs optional-dependencies [ "all" ]);
     gevent = [ gevent ];
     redis = [ redis ];
   };
diff --git a/pkgs/development/python-modules/dsnap/default.nix b/pkgs/development/python-modules/dsnap/default.nix
index 1b8a2bcf27a0..ce3778e9bae8 100644
--- a/pkgs/development/python-modules/dsnap/default.nix
+++ b/pkgs/development/python-modules/dsnap/default.nix
@@ -56,7 +56,7 @@ buildPythonPackage rec {
     mypy-boto3-ebs
     pytestCheckHook
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   # https://github.com/RhinoSecurityLabs/dsnap/issues/26
   # ImportError: cannot import name 'mock_iam' from 'moto'
diff --git a/pkgs/development/python-modules/dulwich/default.nix b/pkgs/development/python-modules/dulwich/default.nix
index 09dd99fbb1e3..75de539d6bb9 100644
--- a/pkgs/development/python-modules/dulwich/default.nix
+++ b/pkgs/development/python-modules/dulwich/default.nix
@@ -79,7 +79,7 @@ buildPythonPackage rec {
     glibcLocales
     pytestCheckHook
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   enabledTestPaths = [ "tests" ];
 
diff --git a/pkgs/development/python-modules/edalize/default.nix b/pkgs/development/python-modules/edalize/default.nix
index 05c8375351d6..90db9ac64aa3 100644
--- a/pkgs/development/python-modules/edalize/default.nix
+++ b/pkgs/development/python-modules/edalize/default.nix
@@ -53,7 +53,7 @@ buildPythonPackage rec {
     which
     yosys
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "edalize" ];
 
diff --git a/pkgs/development/python-modules/energyflow/default.nix b/pkgs/development/python-modules/energyflow/default.nix
index 2fe0be0ad329..41200e2890c5 100644
--- a/pkgs/development/python-modules/energyflow/default.nix
+++ b/pkgs/development/python-modules/energyflow/default.nix
@@ -65,7 +65,7 @@ buildPythonPackage rec {
     pytestCheckHook
     tf-keras
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   disabledTests = [
     # Issues with array
diff --git a/pkgs/development/python-modules/fastavro/default.nix b/pkgs/development/python-modules/fastavro/default.nix
index 04c419eaedcd..64b9eff1723c 100644
--- a/pkgs/development/python-modules/fastavro/default.nix
+++ b/pkgs/development/python-modules/fastavro/default.nix
@@ -57,7 +57,7 @@ buildPythonPackage rec {
     python-dateutil
     zlib-ng
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   # Fails with "AttributeError: module 'fastavro._read_py' has no attribute
   # 'CYTHON_MODULE'." Doesn't appear to be serious. See https://github.com/fastavro/fastavro/issues/112#issuecomment-387638676.
diff --git a/pkgs/development/python-modules/fastmcp/default.nix b/pkgs/development/python-modules/fastmcp/default.nix
index 14a43b3fa688..1048317f71a7 100644
--- a/pkgs/development/python-modules/fastmcp/default.nix
+++ b/pkgs/development/python-modules/fastmcp/default.nix
@@ -85,7 +85,7 @@ buildPythonPackage rec {
     pytestCheckHook
     writableTmpDirAsHomeHook
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies)
+  ++ lib.concatAttrValues optional-dependencies
   ++ inline-snapshot.optional-dependencies.dirty-equals;
 
   disabledTests = [
diff --git a/pkgs/development/python-modules/fickling/default.nix b/pkgs/development/python-modules/fickling/default.nix
index e4887b4a2836..1978b17eec50 100644
--- a/pkgs/development/python-modules/fickling/default.nix
+++ b/pkgs/development/python-modules/fickling/default.nix
@@ -44,7 +44,7 @@ buildPythonPackage rec {
     ];
   };
 
-  nativeCheckInputs = [ pytestCheckHook ] ++ lib.flatten (builtins.attrValues optional-dependencies);
+  nativeCheckInputs = [ pytestCheckHook ] ++ lib.concatAttrValues optional-dependencies;
 
   disabledTestPaths = [
     # https://github.com/trailofbits/fickling/issues/162
diff --git a/pkgs/development/python-modules/flask-dance/default.nix b/pkgs/development/python-modules/flask-dance/default.nix
index 5c6a15fe48e0..0171e1e2181b 100644
--- a/pkgs/development/python-modules/flask-dance/default.nix
+++ b/pkgs/development/python-modules/flask-dance/default.nix
@@ -81,7 +81,7 @@ buildPythonPackage rec {
     ];
   };
 
-  nativeCheckInputs = [ pytestCheckHook ] ++ lib.flatten (lib.attrValues optional-dependencies);
+  nativeCheckInputs = [ pytestCheckHook ] ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "flask_dance" ];
 
diff --git a/pkgs/development/python-modules/flask-jwt-extended/default.nix b/pkgs/development/python-modules/flask-jwt-extended/default.nix
index 5d0274321f88..86a28dd787b0 100644
--- a/pkgs/development/python-modules/flask-jwt-extended/default.nix
+++ b/pkgs/development/python-modules/flask-jwt-extended/default.nix
@@ -39,7 +39,7 @@ buildPythonPackage rec {
   nativeCheckInputs = [
     pytestCheckHook
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "flask_jwt_extended" ];
 
diff --git a/pkgs/development/python-modules/flask/default.nix b/pkgs/development/python-modules/flask/default.nix
index fb57596f1f97..dbfba4b33d95 100644
--- a/pkgs/development/python-modules/flask/default.nix
+++ b/pkgs/development/python-modules/flask/default.nix
@@ -55,7 +55,7 @@ buildPythonPackage rec {
     dotenv = [ python-dotenv ];
   };
 
-  nativeCheckInputs = [ pytestCheckHook ] ++ lib.flatten (lib.attrValues optional-dependencies);
+  nativeCheckInputs = [ pytestCheckHook ] ++ lib.concatAttrValues optional-dependencies;
 
   passthru.tests = {
     inherit
diff --git a/pkgs/development/python-modules/flow-record/default.nix b/pkgs/development/python-modules/flow-record/default.nix
index 9900ba47f2ae..a9f4da73a060 100644
--- a/pkgs/development/python-modules/flow-record/default.nix
+++ b/pkgs/development/python-modules/flow-record/default.nix
@@ -58,7 +58,7 @@ buildPythonPackage rec {
     elastic-transport
     pytest7CheckHook
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "flow.record" ];
 
diff --git a/pkgs/development/python-modules/fnllm/default.nix b/pkgs/development/python-modules/fnllm/default.nix
index dc413e2aca4d..df778008efef 100644
--- a/pkgs/development/python-modules/fnllm/default.nix
+++ b/pkgs/development/python-modules/fnllm/default.nix
@@ -62,7 +62,7 @@ buildPythonPackage rec {
     pytest-cov-stub
     pytestCheckHook
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "fnllm" ];
 
diff --git a/pkgs/development/python-modules/foolscap/default.nix b/pkgs/development/python-modules/foolscap/default.nix
index 2f4ed006b849..2af1174c66ca 100644
--- a/pkgs/development/python-modules/foolscap/default.nix
+++ b/pkgs/development/python-modules/foolscap/default.nix
@@ -52,7 +52,7 @@ buildPythonPackage rec {
     mock
     pytestCheckHook
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "foolscap" ];
 
diff --git a/pkgs/development/python-modules/frictionless/default.nix b/pkgs/development/python-modules/frictionless/default.nix
index 875d88119ace..269670c7981f 100644
--- a/pkgs/development/python-modules/frictionless/default.nix
+++ b/pkgs/development/python-modules/frictionless/default.nix
@@ -195,7 +195,7 @@ buildPythonPackage rec {
     openpyxl
     xlrd
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   disabledTestPaths = [
     # Requires optional dependencies that have not been packaged (commented out above)
diff --git a/pkgs/development/python-modules/githubkit/default.nix b/pkgs/development/python-modules/githubkit/default.nix
index 5c625b117c7b..0e1d6e1e150f 100644
--- a/pkgs/development/python-modules/githubkit/default.nix
+++ b/pkgs/development/python-modules/githubkit/default.nix
@@ -65,7 +65,7 @@ buildPythonPackage rec {
     pytest-cov-stub
     pytest-xdist
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "githubkit" ];
 
diff --git a/pkgs/development/python-modules/glom/default.nix b/pkgs/development/python-modules/glom/default.nix
index bd49c09f12c8..a095a1a5df12 100644
--- a/pkgs/development/python-modules/glom/default.nix
+++ b/pkgs/development/python-modules/glom/default.nix
@@ -41,7 +41,7 @@ buildPythonPackage rec {
   nativeCheckInputs = [
     pytestCheckHook
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   preCheck = ''
     # test_cli.py checks the output of running "glom"
diff --git a/pkgs/development/python-modules/google-auth/default.nix b/pkgs/development/python-modules/google-auth/default.nix
index d9e435c32486..4fdddd4302f7 100644
--- a/pkgs/development/python-modules/google-auth/default.nix
+++ b/pkgs/development/python-modules/google-auth/default.nix
@@ -77,7 +77,7 @@ buildPythonPackage rec {
     pytestCheckHook
     responses
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   disabledTestPaths = [
     "samples/"
diff --git a/pkgs/development/python-modules/google-cloud-spanner/default.nix b/pkgs/development/python-modules/google-cloud-spanner/default.nix
index 19263faa4656..b8ada5017686 100644
--- a/pkgs/development/python-modules/google-cloud-spanner/default.nix
+++ b/pkgs/development/python-modules/google-cloud-spanner/default.nix
@@ -79,7 +79,7 @@ buildPythonPackage rec {
     pytest-asyncio
     pytestCheckHook
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   preCheck = ''
     # prevent google directory from shadowing google imports
diff --git a/pkgs/development/python-modules/groq/default.nix b/pkgs/development/python-modules/groq/default.nix
index b2fb92b15eb8..700a323f475b 100644
--- a/pkgs/development/python-modules/groq/default.nix
+++ b/pkgs/development/python-modules/groq/default.nix
@@ -67,7 +67,7 @@ buildPythonPackage rec {
     pytestCheckHook
     respx
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "groq" ];
 
diff --git a/pkgs/development/python-modules/gruut/default.nix b/pkgs/development/python-modules/gruut/default.nix
index 723a15efea81..34db362216ec 100644
--- a/pkgs/development/python-modules/gruut/default.nix
+++ b/pkgs/development/python-modules/gruut/default.nix
@@ -92,7 +92,7 @@ buildPythonPackage rec {
   nativeCheckInputs = [
     pytestCheckHook
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   disabledTests = [
     # https://github.com/rhasspy/gruut/issues/25
diff --git a/pkgs/development/python-modules/gstools/default.nix b/pkgs/development/python-modules/gstools/default.nix
index 3e4a42c032b1..d3f5d03de164 100644
--- a/pkgs/development/python-modules/gstools/default.nix
+++ b/pkgs/development/python-modules/gstools/default.nix
@@ -65,7 +65,7 @@ buildPythonPackage rec {
     pytestCheckHook
     pytest-cov-stub
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   meta = {
     description = "Geostatistical toolbox";
diff --git a/pkgs/development/python-modules/gunicorn/default.nix b/pkgs/development/python-modules/gunicorn/default.nix
index e5d6bff39640..c665a41d6f57 100644
--- a/pkgs/development/python-modules/gunicorn/default.nix
+++ b/pkgs/development/python-modules/gunicorn/default.nix
@@ -52,7 +52,7 @@ buildPythonPackage rec {
     pytestCheckHook
     pytest-cov-stub
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   meta = {
     description = "WSGI HTTP Server for UNIX, fast clients and sleepy applications";
diff --git a/pkgs/development/python-modules/hishel/default.nix b/pkgs/development/python-modules/hishel/default.nix
index eaf719c49358..ce93ef214501 100644
--- a/pkgs/development/python-modules/hishel/default.nix
+++ b/pkgs/development/python-modules/hishel/default.nix
@@ -50,7 +50,7 @@ buildPythonPackage rec {
     pytestCheckHook
     trio
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "hishel" ];
 
diff --git a/pkgs/development/python-modules/httpcore/default.nix b/pkgs/development/python-modules/httpcore/default.nix
index 100a3d25e772..10f8b37b2c4a 100644
--- a/pkgs/development/python-modules/httpcore/default.nix
+++ b/pkgs/development/python-modules/httpcore/default.nix
@@ -60,7 +60,7 @@ buildPythonPackage rec {
     pytest-trio
     pytestCheckHook
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "httpcore" ];
 
diff --git a/pkgs/development/python-modules/httpx/default.nix b/pkgs/development/python-modules/httpx/default.nix
index 74eeaedd9281..1ac2ea694b2a 100644
--- a/pkgs/development/python-modules/httpx/default.nix
+++ b/pkgs/development/python-modules/httpx/default.nix
@@ -79,7 +79,7 @@ buildPythonPackage rec {
     trustme
     uvicorn
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   # testsuite wants to find installed packages for testing entrypoint
   preCheck = ''
diff --git a/pkgs/development/python-modules/hypercorn/default.nix b/pkgs/development/python-modules/hypercorn/default.nix
index 2d468bd64d74..ae8b9cf44396 100644
--- a/pkgs/development/python-modules/hypercorn/default.nix
+++ b/pkgs/development/python-modules/hypercorn/default.nix
@@ -57,7 +57,7 @@ buildPythonPackage rec {
     pytest-trio
     pytestCheckHook
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   __darwinAllowLocalNetworking = true;
 
diff --git a/pkgs/development/python-modules/igraph/default.nix b/pkgs/development/python-modules/igraph/default.nix
index 59974797d4e5..e5e2c82463c6 100644
--- a/pkgs/development/python-modules/igraph/default.nix
+++ b/pkgs/development/python-modules/igraph/default.nix
@@ -62,7 +62,7 @@ buildPythonPackage rec {
   nativeCheckInputs = [
     pytestCheckHook
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   disabledTests = [
     "testAuthorityScore"
diff --git a/pkgs/development/python-modules/imageio/default.nix b/pkgs/development/python-modules/imageio/default.nix
index 40e134e303f1..ac008f45da4f 100644
--- a/pkgs/development/python-modules/imageio/default.nix
+++ b/pkgs/development/python-modules/imageio/default.nix
@@ -94,7 +94,7 @@ buildPythonPackage rec {
     writableTmpDirAsHomeHook
   ]
   ++ fsspec.optional-dependencies.github
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pytestFlags = [ "--test-images=file://${test_images}" ];
 
diff --git a/pkgs/development/python-modules/inline-snapshot/default.nix b/pkgs/development/python-modules/inline-snapshot/default.nix
index 3e2c78c98cce..2b495f7dc510 100644
--- a/pkgs/development/python-modules/inline-snapshot/default.nix
+++ b/pkgs/development/python-modules/inline-snapshot/default.nix
@@ -58,7 +58,7 @@ buildPythonPackage rec {
     pytestCheckHook
     time-machine
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   optional-dependencies = {
     black = [ black ];
diff --git a/pkgs/development/python-modules/intake/default.nix b/pkgs/development/python-modules/intake/default.nix
index 04101b3c90af..d4f4b05437c9 100644
--- a/pkgs/development/python-modules/intake/default.nix
+++ b/pkgs/development/python-modules/intake/default.nix
@@ -63,7 +63,7 @@ buildPythonPackage rec {
     intake-parquet
     pytestCheckHook
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   optional-dependencies = {
     server = [
diff --git a/pkgs/development/python-modules/iplotx/default.nix b/pkgs/development/python-modules/iplotx/default.nix
index 37e0f98ec8c0..6f69ca7818f2 100644
--- a/pkgs/development/python-modules/iplotx/default.nix
+++ b/pkgs/development/python-modules/iplotx/default.nix
@@ -55,7 +55,7 @@ buildPythonPackage rec {
     "test_labels_and_colors"
   ];
 
-  nativeCheckInputs = [ pytestCheckHook ] ++ lib.flatten (lib.attrValues optional-dependencies);
+  nativeCheckInputs = [ pytestCheckHook ] ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "iplotx" ];
 
diff --git a/pkgs/development/python-modules/joserfc/default.nix b/pkgs/development/python-modules/joserfc/default.nix
index 5cbe913821b5..6c7580873c31 100644
--- a/pkgs/development/python-modules/joserfc/default.nix
+++ b/pkgs/development/python-modules/joserfc/default.nix
@@ -34,7 +34,7 @@ buildPythonPackage rec {
     drafts = [ pycryptodome ];
   };
 
-  nativeCheckInputs = [ pytestCheckHook ] ++ lib.flatten (lib.attrValues optional-dependencies);
+  nativeCheckInputs = [ pytestCheckHook ] ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "joserfc" ];
 
diff --git a/pkgs/development/python-modules/jupyter-events/default.nix b/pkgs/development/python-modules/jupyter-events/default.nix
index 895ceafa250e..7af4f0f6ecf7 100644
--- a/pkgs/development/python-modules/jupyter-events/default.nix
+++ b/pkgs/development/python-modules/jupyter-events/default.nix
@@ -64,7 +64,7 @@ buildPythonPackage rec {
     pytest-console-scripts
     pytestCheckHook
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   preCheck = ''
     export PATH="$out/bin:$PATH"
diff --git a/pkgs/development/python-modules/kafka-python-ng/default.nix b/pkgs/development/python-modules/kafka-python-ng/default.nix
index 81036644f108..82579c97b01d 100644
--- a/pkgs/development/python-modules/kafka-python-ng/default.nix
+++ b/pkgs/development/python-modules/kafka-python-ng/default.nix
@@ -45,7 +45,7 @@ buildPythonPackage rec {
     pytestCheckHook
     xxhash
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   meta = {
     changelog = "https://github.com/wbarnha/kafka-python-ng/releases/tag/v${version}";
diff --git a/pkgs/development/python-modules/keystoneauth1/default.nix b/pkgs/development/python-modules/keystoneauth1/default.nix
index 9fa03f7c7158..bf3ee99c9cbc 100644
--- a/pkgs/development/python-modules/keystoneauth1/default.nix
+++ b/pkgs/development/python-modules/keystoneauth1/default.nix
@@ -46,7 +46,7 @@ buildPythonPackage rec {
     typing-extensions
   ]
   # TODO: remove this workaround and fix breakages
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   optional-dependencies = {
     betamax = [
@@ -69,7 +69,7 @@ buildPythonPackage rec {
     testresources
     testtools
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   # test_keystoneauth_betamax_fixture is incompatible with urllib3 2.0.0
   # https://bugs.launchpad.net/keystoneauth/+bug/2020112
diff --git a/pkgs/development/python-modules/kombu/default.nix b/pkgs/development/python-modules/kombu/default.nix
index e40453eeee4c..b5878244d4c7 100644
--- a/pkgs/development/python-modules/kombu/default.nix
+++ b/pkgs/development/python-modules/kombu/default.nix
@@ -83,7 +83,7 @@ buildPythonPackage rec {
     hypothesis
     pytestCheckHook
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "kombu" ];
 
diff --git a/pkgs/development/python-modules/kserve/default.nix b/pkgs/development/python-modules/kserve/default.nix
index c547a18e5cff..23df8624b55e 100644
--- a/pkgs/development/python-modules/kserve/default.nix
+++ b/pkgs/development/python-modules/kserve/default.nix
@@ -130,7 +130,7 @@ buildPythonPackage rec {
     pytestCheckHook
     tomlkit
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "kserve" ];
 
diff --git a/pkgs/development/python-modules/kubernetes/default.nix b/pkgs/development/python-modules/kubernetes/default.nix
index 7861d5e2ff1b..a744f4086c65 100644
--- a/pkgs/development/python-modules/kubernetes/default.nix
+++ b/pkgs/development/python-modules/kubernetes/default.nix
@@ -61,7 +61,7 @@ buildPythonPackage rec {
     mock
     pytestCheckHook
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   disabledTests = lib.optionals stdenv.hostPlatform.isDarwin [
     # AssertionError: <class 'urllib3.poolmanager.ProxyManager'> != <class 'urllib3.poolmanager.Poolmanager'>
diff --git a/pkgs/development/python-modules/lance-namespace/default.nix b/pkgs/development/python-modules/lance-namespace/default.nix
index 12198c334963..38c262fada14 100644
--- a/pkgs/development/python-modules/lance-namespace/default.nix
+++ b/pkgs/development/python-modules/lance-namespace/default.nix
@@ -74,7 +74,7 @@ buildPythonPackage rec {
     pylance
     pytestCheckHook
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   # Tests require pylance, which is a circular dependency
   doCheck = false;
diff --git a/pkgs/development/python-modules/langgraph-cli/default.nix b/pkgs/development/python-modules/langgraph-cli/default.nix
index d3a285ec519a..4ed6fcf9e26c 100644
--- a/pkgs/development/python-modules/langgraph-cli/default.nix
+++ b/pkgs/development/python-modules/langgraph-cli/default.nix
@@ -56,7 +56,7 @@ buildPythonPackage rec {
     pytestCheckHook
     docker-compose
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   enabledTestPaths = [ "tests/unit_tests" ];
 
diff --git a/pkgs/development/python-modules/libpass/default.nix b/pkgs/development/python-modules/libpass/default.nix
index 5f02a27cc3a3..8839bed97133 100644
--- a/pkgs/development/python-modules/libpass/default.nix
+++ b/pkgs/development/python-modules/libpass/default.nix
@@ -37,7 +37,7 @@ buildPythonPackage rec {
     pytest-xdist
     pytestCheckHook
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "passlib" ];
 
diff --git a/pkgs/development/python-modules/limits/default.nix b/pkgs/development/python-modules/limits/default.nix
index 6a6bf2ab4373..cc4dbd03f3f8 100644
--- a/pkgs/development/python-modules/limits/default.nix
+++ b/pkgs/development/python-modules/limits/default.nix
@@ -97,7 +97,7 @@ buildPythonPackage rec {
     pytest-lazy-fixtures
     pytestCheckHook
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pytestFlags = [ "--benchmark-disable" ];
 
diff --git a/pkgs/development/python-modules/llama-stack-client/default.nix b/pkgs/development/python-modules/llama-stack-client/default.nix
index ccf1ff2bc72e..572a79537e89 100644
--- a/pkgs/development/python-modules/llama-stack-client/default.nix
+++ b/pkgs/development/python-modules/llama-stack-client/default.nix
@@ -83,7 +83,7 @@ buildPythonPackage rec {
     pytestCheckHook
     respx
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "llama_stack_client" ];
 
diff --git a/pkgs/development/python-modules/logbook/default.nix b/pkgs/development/python-modules/logbook/default.nix
index bc286c00dc00..a5ec93ce6652 100644
--- a/pkgs/development/python-modules/logbook/default.nix
+++ b/pkgs/development/python-modules/logbook/default.nix
@@ -55,7 +55,7 @@ buildPythonPackage rec {
     pytestCheckHook
     pytest-rerunfailures
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   # Some of the tests use localhost networking.
   __darwinAllowLocalNetworking = true;
diff --git a/pkgs/development/python-modules/mako/default.nix b/pkgs/development/python-modules/mako/default.nix
index d5a4895cab57..26722271b75d 100644
--- a/pkgs/development/python-modules/mako/default.nix
+++ b/pkgs/development/python-modules/mako/default.nix
@@ -49,7 +49,7 @@ buildPythonPackage rec {
     mock
     pytestCheckHook
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   disabledTests = lib.optionals isPyPy [
     # https://github.com/sqlalchemy/mako/issues/315
diff --git a/pkgs/development/python-modules/manifest-ml/default.nix b/pkgs/development/python-modules/manifest-ml/default.nix
index 5520d57aaad6..f21bb697429a 100644
--- a/pkgs/development/python-modules/manifest-ml/default.nix
+++ b/pkgs/development/python-modules/manifest-ml/default.nix
@@ -85,7 +85,7 @@ buildPythonPackage rec {
   nativeCheckInputs = [
     pytestCheckHook
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   preCheck = ''
     export HOME=$TMPDIR
diff --git a/pkgs/development/python-modules/markdown2/default.nix b/pkgs/development/python-modules/markdown2/default.nix
index e4a6cfd497a0..34eb306ee685 100644
--- a/pkgs/development/python-modules/markdown2/default.nix
+++ b/pkgs/development/python-modules/markdown2/default.nix
@@ -34,7 +34,7 @@ buildPythonPackage rec {
     code_syntax_highlighting = [ pygments ];
     wavedrom = [ wavedrom ];
     latex = [ latex2mathml ];
-    all = lib.flatten (lib.attrValues (lib.removeAttrs optional-dependencies [ "all" ]));
+    all = lib.concatAttrValues (lib.removeAttrs optional-dependencies [ "all" ]);
   };
 
   meta = {
diff --git a/pkgs/development/python-modules/mashumaro/default.nix b/pkgs/development/python-modules/mashumaro/default.nix
index 499193da4cf0..80f763451ffe 100644
--- a/pkgs/development/python-modules/mashumaro/default.nix
+++ b/pkgs/development/python-modules/mashumaro/default.nix
@@ -45,7 +45,7 @@ buildPythonPackage rec {
     pytest-mock
     pytestCheckHook
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "mashumaro" ];
 
diff --git a/pkgs/development/python-modules/mastodon-py/default.nix b/pkgs/development/python-modules/mastodon-py/default.nix
index 99790de5f2f5..ccf75e802b79 100644
--- a/pkgs/development/python-modules/mastodon-py/default.nix
+++ b/pkgs/development/python-modules/mastodon-py/default.nix
@@ -56,7 +56,7 @@ buildPythonPackage rec {
     pytest-vcr
     requests-mock
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   # disabledTests = [
   #   "test_notifications_dismiss_pre_2_9_2"
diff --git a/pkgs/development/python-modules/mcp/default.nix b/pkgs/development/python-modules/mcp/default.nix
index 3a5adae06097..a1561ed3d4f0 100644
--- a/pkgs/development/python-modules/mcp/default.nix
+++ b/pkgs/development/python-modules/mcp/default.nix
@@ -109,7 +109,7 @@ buildPythonPackage rec {
     pytestCheckHook
     requests
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   disabledTests = [
     # attempts to run the package manager uv
diff --git a/pkgs/development/python-modules/meshtastic/default.nix b/pkgs/development/python-modules/meshtastic/default.nix
index 4686169c3865..f95265c204d4 100644
--- a/pkgs/development/python-modules/meshtastic/default.nix
+++ b/pkgs/development/python-modules/meshtastic/default.nix
@@ -91,7 +91,7 @@ buildPythonPackage rec {
     hypothesis
     pytestCheckHook
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   preCheck = ''
     export PATH="$PATH:$out/bin";
diff --git a/pkgs/development/python-modules/minari/default.nix b/pkgs/development/python-modules/minari/default.nix
index bfbac43d3340..e71d3f557ec5 100644
--- a/pkgs/development/python-modules/minari/default.nix
+++ b/pkgs/development/python-modules/minari/default.nix
@@ -80,7 +80,7 @@ buildPythonPackage rec {
     jaxlib
     pytestCheckHook
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   disabledTests = [
     # Require internet access
diff --git a/pkgs/development/python-modules/mir-eval/default.nix b/pkgs/development/python-modules/mir-eval/default.nix
index ef580ec384ee..e72fe775c5fc 100644
--- a/pkgs/development/python-modules/mir-eval/default.nix
+++ b/pkgs/development/python-modules/mir-eval/default.nix
@@ -39,7 +39,7 @@ buildPythonPackage rec {
     pytest-cov-stub
     pytest-mpl
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   preCheck = ''
     pushd tests
diff --git a/pkgs/development/python-modules/mne/default.nix b/pkgs/development/python-modules/mne/default.nix
index 1a55f3a2a85f..d4869fc287fb 100644
--- a/pkgs/development/python-modules/mne/default.nix
+++ b/pkgs/development/python-modules/mne/default.nix
@@ -78,7 +78,7 @@ buildPythonPackage rec {
     pytest-timeout
     writableTmpDirAsHomeHook
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   preCheck = ''
     export MNE_SKIP_TESTING_DATASET_TESTS=true
diff --git a/pkgs/development/python-modules/mocket/default.nix b/pkgs/development/python-modules/mocket/default.nix
index 0f23f05161c8..44c957292faa 100644
--- a/pkgs/development/python-modules/mocket/default.nix
+++ b/pkgs/development/python-modules/mocket/default.nix
@@ -73,7 +73,7 @@ buildPythonPackage rec {
     requests
     sure
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   # Skip http tests, they require network access
   env.SKIP_TRUE_HTTP = true;
diff --git a/pkgs/development/python-modules/modern-colorthief/default.nix b/pkgs/development/python-modules/modern-colorthief/default.nix
index 52932819ae48..a79d66a51e64 100644
--- a/pkgs/development/python-modules/modern-colorthief/default.nix
+++ b/pkgs/development/python-modules/modern-colorthief/default.nix
@@ -38,7 +38,7 @@ buildPythonPackage rec {
     ];
   };
 
-  nativeCheckInputs = [ pytestCheckHook ] ++ lib.attrValues optional-dependencies;
+  nativeCheckInputs = [ pytestCheckHook ] ++ lib.concatAttrValues optional-dependencies;
 
   disabledTestPaths = [
     # Requires `fast_colorthief`, which isn't packaged
diff --git a/pkgs/development/python-modules/moviepy/default.nix b/pkgs/development/python-modules/moviepy/default.nix
index e393427e61d9..1c1977195699 100644
--- a/pkgs/development/python-modules/moviepy/default.nix
+++ b/pkgs/development/python-modules/moviepy/default.nix
@@ -70,7 +70,7 @@ buildPythonPackage rec {
     pytest-timeout
     pytestCheckHook
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   # See https://github.com/NixOS/nixpkgs/issues/381908 and https://github.com/NixOS/nixpkgs/issues/385450.
   pytestFlags = [ "--timeout=600" ];
diff --git a/pkgs/development/python-modules/mrjob/default.nix b/pkgs/development/python-modules/mrjob/default.nix
index fa36ae67a44a..2c0978688800 100644
--- a/pkgs/development/python-modules/mrjob/default.nix
+++ b/pkgs/development/python-modules/mrjob/default.nix
@@ -72,7 +72,7 @@ buildPythonPackage rec {
     unittestCheckHook
     warcio
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   unittestFlagsArray = [ "-v" ];
 
diff --git a/pkgs/development/python-modules/mypy/default.nix b/pkgs/development/python-modules/mypy/default.nix
index a5aefa297340..6c61c08f53fb 100644
--- a/pkgs/development/python-modules/mypy/default.nix
+++ b/pkgs/development/python-modules/mypy/default.nix
@@ -110,7 +110,7 @@ buildPythonPackage rec {
     setuptools
     tomli
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   disabledTests = [
     # fails with typing-extensions>=4.10
diff --git a/pkgs/development/python-modules/narwhals/default.nix b/pkgs/development/python-modules/narwhals/default.nix
index 049411653ca0..89901dab34c9 100644
--- a/pkgs/development/python-modules/narwhals/default.nix
+++ b/pkgs/development/python-modules/narwhals/default.nix
@@ -57,7 +57,7 @@ buildPythonPackage rec {
     pytest-env
     pytestCheckHook
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "narwhals" ];
 
diff --git a/pkgs/development/python-modules/nibe/default.nix b/pkgs/development/python-modules/nibe/default.nix
index 3207956ae829..7c94bfeed8aa 100644
--- a/pkgs/development/python-modules/nibe/default.nix
+++ b/pkgs/development/python-modules/nibe/default.nix
@@ -56,7 +56,7 @@ buildPythonPackage rec {
     pytest-asyncio
     pytestCheckHook
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "nibe" ];
 
diff --git a/pkgs/development/python-modules/nicegui/default.nix b/pkgs/development/python-modules/nicegui/default.nix
index 21535d27fe8a..f4a97b00f078 100644
--- a/pkgs/development/python-modules/nicegui/default.nix
+++ b/pkgs/development/python-modules/nicegui/default.nix
@@ -105,7 +105,7 @@ buildPythonPackage rec {
     webdriver-manager
     writableTmpDirAsHomeHook
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "nicegui" ];
 
diff --git a/pkgs/development/python-modules/noisereduce/default.nix b/pkgs/development/python-modules/noisereduce/default.nix
index 8ceb9cccd102..269d8db25d17 100644
--- a/pkgs/development/python-modules/noisereduce/default.nix
+++ b/pkgs/development/python-modules/noisereduce/default.nix
@@ -38,7 +38,7 @@ buildPythonPackage rec {
     PyTorch = [ torch ];
   };
 
-  nativeCheckInputs = [ pytestCheckHook ] ++ lib.flatten (builtins.attrValues optional-dependencies);
+  nativeCheckInputs = [ pytestCheckHook ] ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "noisereduce" ];
 
diff --git a/pkgs/development/python-modules/nox/default.nix b/pkgs/development/python-modules/nox/default.nix
index e34ef6f7d9b1..e160bb53c32a 100644
--- a/pkgs/development/python-modules/nox/default.nix
+++ b/pkgs/development/python-modules/nox/default.nix
@@ -68,7 +68,7 @@ buildPythonPackage rec {
     pytestCheckHook
     writableTmpDirAsHomeHook
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "nox" ];
 
diff --git a/pkgs/development/python-modules/numcodecs/default.nix b/pkgs/development/python-modules/numcodecs/default.nix
index ae55cda810bf..70f5a96196be 100644
--- a/pkgs/development/python-modules/numcodecs/default.nix
+++ b/pkgs/development/python-modules/numcodecs/default.nix
@@ -62,7 +62,7 @@ buildPythonPackage rec {
     pytestCheckHook
     importlib-metadata
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   # https://github.com/NixOS/nixpkgs/issues/255262
   preCheck = "pushd $out";
diff --git a/pkgs/development/python-modules/nutils/default.nix b/pkgs/development/python-modules/nutils/default.nix
index 2c720c5cc3d7..0a493af3926a 100644
--- a/pkgs/development/python-modules/nutils/default.nix
+++ b/pkgs/development/python-modules/nutils/default.nix
@@ -53,7 +53,7 @@ buildPythonPackage rec {
     pkgs.graphviz
     pytestCheckHook
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   disabledTests = [
     # Error: invalid value 'x' for farg: loading 'x' as float
diff --git a/pkgs/development/python-modules/oauthenticator/default.nix b/pkgs/development/python-modules/oauthenticator/default.nix
index 63afaab59a7c..f1077f87f572 100644
--- a/pkgs/development/python-modules/oauthenticator/default.nix
+++ b/pkgs/development/python-modules/oauthenticator/default.nix
@@ -58,7 +58,7 @@ buildPythonPackage rec {
     pytestCheckHook
     requests-mock
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   disabledTests = [
     # Tests are outdated, https://github.com/jupyterhub/oauthenticator/issues/432
diff --git a/pkgs/development/python-modules/oauthlib/default.nix b/pkgs/development/python-modules/oauthlib/default.nix
index c34c9ccfc667..5c41ef0edf3a 100644
--- a/pkgs/development/python-modules/oauthlib/default.nix
+++ b/pkgs/development/python-modules/oauthlib/default.nix
@@ -43,7 +43,7 @@ buildPythonPackage rec {
     mock
     pytestCheckHook
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   disabledTests = [
     # too narrow time comparison issues
diff --git a/pkgs/development/python-modules/odc-loader/default.nix b/pkgs/development/python-modules/odc-loader/default.nix
index 6fb6f3422ca8..22ea63f4a7d2 100644
--- a/pkgs/development/python-modules/odc-loader/default.nix
+++ b/pkgs/development/python-modules/odc-loader/default.nix
@@ -50,7 +50,7 @@ buildPythonPackage rec {
   optional-dependencies = {
     botocore = [ botocore ];
     zarr = [ zarr ];
-    all = lib.flatten (lib.attrValues (lib.removeAttrs optional-dependencies [ "all" ]));
+    all = lib.concatAttrValues (lib.removeAttrs optional-dependencies [ "all" ]);
   };
 
   nativeCheckInputs = [
diff --git a/pkgs/development/python-modules/okonomiyaki/default.nix b/pkgs/development/python-modules/okonomiyaki/default.nix
index 5ee380a8c820..bd258fea9fea 100644
--- a/pkgs/development/python-modules/okonomiyaki/default.nix
+++ b/pkgs/development/python-modules/okonomiyaki/default.nix
@@ -57,7 +57,7 @@ buildPythonPackage rec {
     pytestCheckHook
     testfixtures
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   preCheck = ''
     substituteInPlace okonomiyaki/runtimes/tests/test_runtime.py \
diff --git a/pkgs/development/python-modules/openapi-core/default.nix b/pkgs/development/python-modules/openapi-core/default.nix
index 639d273bb3df..b62745c9691b 100644
--- a/pkgs/development/python-modules/openapi-core/default.nix
+++ b/pkgs/development/python-modules/openapi-core/default.nix
@@ -83,7 +83,7 @@ buildPythonPackage rec {
     responses
     webob
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   disabledTestPaths = [
     # Requires secrets and additional configuration
diff --git a/pkgs/development/python-modules/outlines-core/default.nix b/pkgs/development/python-modules/outlines-core/default.nix
index cca2b10ff673..945875486443 100644
--- a/pkgs/development/python-modules/outlines-core/default.nix
+++ b/pkgs/development/python-modules/outlines-core/default.nix
@@ -97,7 +97,7 @@ buildPythonPackage rec {
     rm -rf outlines_core
   '';
 
-  nativeCheckInputs = [ pytestCheckHook ] ++ lib.flatten (lib.attrValues optional-dependencies);
+  nativeCheckInputs = [ pytestCheckHook ] ++ lib.concatAttrValues optional-dependencies;
 
   disabledTests = [
     # Tests that need to download from Hugging Face Hub.
diff --git a/pkgs/development/python-modules/pandas/default.nix b/pkgs/development/python-modules/pandas/default.nix
index 970a880d0fe6..f6445d838ee2 100644
--- a/pkgs/development/python-modules/pandas/default.nix
+++ b/pkgs/development/python-modules/pandas/default.nix
@@ -184,7 +184,7 @@ let
       pytest-xdist
       pytestCheckHook
     ]
-    ++ lib.flatten (lib.attrValues optional-dependencies)
+    ++ lib.concatAttrValues optional-dependencies
     ++ lib.optionals (stdenv.hostPlatform.isLinux) [
       # for locale executable
       glibc
diff --git a/pkgs/development/python-modules/paramiko/default.nix b/pkgs/development/python-modules/paramiko/default.nix
index 7cb53debdf75..1c96cda8a4da 100644
--- a/pkgs/development/python-modules/paramiko/default.nix
+++ b/pkgs/development/python-modules/paramiko/default.nix
@@ -48,7 +48,7 @@ buildPythonPackage rec {
     pytestCheckHook
     pytest-relaxed
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "paramiko" ];
 
diff --git a/pkgs/development/python-modules/persist-queue/default.nix b/pkgs/development/python-modules/persist-queue/default.nix
index 72c662c2680f..41aff20516e1 100644
--- a/pkgs/development/python-modules/persist-queue/default.nix
+++ b/pkgs/development/python-modules/persist-queue/default.nix
@@ -44,7 +44,7 @@ buildPythonPackage rec {
     pytest-asyncio
     pytestCheckHook
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "persistqueue" ];
 
diff --git a/pkgs/development/python-modules/pettingzoo/default.nix b/pkgs/development/python-modules/pettingzoo/default.nix
index e8fa3a1ed962..ad3ab0ca58e9 100644
--- a/pkgs/development/python-modules/pettingzoo/default.nix
+++ b/pkgs/development/python-modules/pettingzoo/default.nix
@@ -53,7 +53,7 @@ buildPythonPackage rec {
   ];
 
   optional-dependencies = {
-    all = lib.flatten (lib.attrValues (lib.removeAttrs optional-dependencies [ "all" ]));
+    all = lib.concatAttrValues (lib.removeAttrs optional-dependencies [ "all" ]);
     atari = [
       # multi-agent-ale-py
       pygame
diff --git a/pkgs/development/python-modules/piccolo/default.nix b/pkgs/development/python-modules/piccolo/default.nix
index 714116e2d0f0..7e803cc6d87a 100644
--- a/pkgs/development/python-modules/piccolo/default.nix
+++ b/pkgs/development/python-modules/piccolo/default.nix
@@ -59,7 +59,7 @@ buildPythonPackage rec {
     pytestCheckHook
     python-dateutil
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "piccolo" ];
 
diff --git a/pkgs/development/python-modules/pillow/default.nix b/pkgs/development/python-modules/pillow/default.nix
index a2cfc6de6be0..556236b3b998 100644
--- a/pkgs/development/python-modules/pillow/default.nix
+++ b/pkgs/development/python-modules/pillow/default.nix
@@ -109,7 +109,7 @@ buildPythonPackage rec {
     pytestCheckHook
     numpy
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   disabledTests = [
     # Code quality mismathch 9 vs 10
diff --git a/pkgs/development/python-modules/pins/default.nix b/pkgs/development/python-modules/pins/default.nix
index 122fb5d04f48..8910dc7d6146 100644
--- a/pkgs/development/python-modules/pins/default.nix
+++ b/pkgs/development/python-modules/pins/default.nix
@@ -76,7 +76,7 @@ buildPythonPackage rec {
     pytest-parallel
     pytestCheckHook
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "pins" ];
 
diff --git a/pkgs/development/python-modules/pipdeptree/default.nix b/pkgs/development/python-modules/pipdeptree/default.nix
index 0d6be4e00581..b3115c303aa7 100644
--- a/pkgs/development/python-modules/pipdeptree/default.nix
+++ b/pkgs/development/python-modules/pipdeptree/default.nix
@@ -55,7 +55,7 @@ buildPythonPackage rec {
     pytestCheckHook
     virtualenv
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "pipdeptree" ];
 
diff --git a/pkgs/development/python-modules/planetary-computer/default.nix b/pkgs/development/python-modules/planetary-computer/default.nix
index 7bc6d0d61641..375d06d21c83 100644
--- a/pkgs/development/python-modules/planetary-computer/default.nix
+++ b/pkgs/development/python-modules/planetary-computer/default.nix
@@ -55,7 +55,7 @@ buildPythonPackage rec {
   optional-dependencies = {
     adlfs = [ adlfs ];
     azure = [ azure-storage-blob ];
-    all = lib.flatten (lib.attrValues (lib.removeAttrs optional-dependencies [ "all" ]));
+    all = lib.concatAttrValues (lib.removeAttrs optional-dependencies [ "all" ]);
   };
 
   pythonImportsCheck = [
diff --git a/pkgs/development/python-modules/plotly/default.nix b/pkgs/development/python-modules/plotly/default.nix
index 72713af57622..5d60007138e4 100644
--- a/pkgs/development/python-modules/plotly/default.nix
+++ b/pkgs/development/python-modules/plotly/default.nix
@@ -90,7 +90,7 @@ buildPythonPackage rec {
     which
     xarray
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   disabledTests = [
     # failed pinning test, sensitive to dep versions
diff --git a/pkgs/development/python-modules/plumbum/default.nix b/pkgs/development/python-modules/plumbum/default.nix
index 64750378f233..45173aec4cba 100644
--- a/pkgs/development/python-modules/plumbum/default.nix
+++ b/pkgs/development/python-modules/plumbum/default.nix
@@ -43,7 +43,7 @@ buildPythonPackage rec {
     pytest-timeout
     pytestCheckHook
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   preCheck = ''
     export HOME=$TMP
diff --git a/pkgs/development/python-modules/powerapi/default.nix b/pkgs/development/python-modules/powerapi/default.nix
index b7b8b5835ea7..aeae78b3f09f 100644
--- a/pkgs/development/python-modules/powerapi/default.nix
+++ b/pkgs/development/python-modules/powerapi/default.nix
@@ -51,7 +51,7 @@ buildPythonPackage rec {
     pytestCheckHook
     pytest-timeout
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "powerapi" ];
 
diff --git a/pkgs/development/python-modules/pproxy/default.nix b/pkgs/development/python-modules/pproxy/default.nix
index f652fa2b13ac..8a379777a2fa 100644
--- a/pkgs/development/python-modules/pproxy/default.nix
+++ b/pkgs/development/python-modules/pproxy/default.nix
@@ -37,7 +37,7 @@ buildPythonPackage rec {
     daemon = [ python-daemon ];
   };
 
-  nativeCheckInputs = lib.flatten (lib.attrValues optional-dependencies);
+  nativeCheckInputs = lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "pproxy" ];
 
diff --git a/pkgs/development/python-modules/prance/default.nix b/pkgs/development/python-modules/prance/default.nix
index 05ff1289ca24..f789a3fab12d 100644
--- a/pkgs/development/python-modules/prance/default.nix
+++ b/pkgs/development/python-modules/prance/default.nix
@@ -55,7 +55,7 @@ buildPythonPackage rec {
     pytest-cov-stub
     pytestCheckHook
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   # Disable tests that require network
   disabledTestPaths = [ "tests/test_convert.py" ];
diff --git a/pkgs/development/python-modules/prometheus-client/default.nix b/pkgs/development/python-modules/prometheus-client/default.nix
index 88e9c6fff24e..0eb0ae66474f 100644
--- a/pkgs/development/python-modules/prometheus-client/default.nix
+++ b/pkgs/development/python-modules/prometheus-client/default.nix
@@ -29,7 +29,7 @@ buildPythonPackage rec {
 
   __darwinAllowLocalNetworking = true;
 
-  nativeCheckInputs = [ pytestCheckHook ] ++ lib.flatten (lib.attrValues optional-dependencies);
+  nativeCheckInputs = [ pytestCheckHook ] ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "prometheus_client" ];
 
diff --git a/pkgs/development/python-modules/prowlpy/default.nix b/pkgs/development/python-modules/prowlpy/default.nix
index 1c854f0136e8..b08a4663bed0 100644
--- a/pkgs/development/python-modules/prowlpy/default.nix
+++ b/pkgs/development/python-modules/prowlpy/default.nix
@@ -48,7 +48,7 @@ buildPythonPackage rec {
     pytestCheckHook
     respx
   ]
-  ++ lib.concatLists (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   # tests fail without this
   pytestFlags = [ "-v" ];
diff --git a/pkgs/development/python-modules/pulsar-client/default.nix b/pkgs/development/python-modules/pulsar-client/default.nix
index 2919a84f8e79..7a6e46e99efc 100644
--- a/pkgs/development/python-modules/pulsar-client/default.nix
+++ b/pkgs/development/python-modules/pulsar-client/default.nix
@@ -67,7 +67,7 @@ buildPythonPackage rec {
       ratelimit
     ];
     avro = [ fastavro ];
-    all = lib.flatten (lib.attrValues (lib.removeAttrs optional-dependencies [ "all" ]));
+    all = lib.concatAttrValues (lib.removeAttrs optional-dependencies [ "all" ]);
   };
 
   nativeCheckInputs = [
diff --git a/pkgs/development/python-modules/py-sucks/default.nix b/pkgs/development/python-modules/py-sucks/default.nix
index 07301cf2090a..9d9373a3e33b 100644
--- a/pkgs/development/python-modules/py-sucks/default.nix
+++ b/pkgs/development/python-modules/py-sucks/default.nix
@@ -45,7 +45,7 @@ buildPythonPackage rec {
     requests-mock
     pytestCheckHook
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   disabledTests = [
     # assumes $HOME is at a specific place
diff --git a/pkgs/development/python-modules/pycyphal/default.nix b/pkgs/development/python-modules/pycyphal/default.nix
index 8a5a10f2cfba..32d68cf73ce8 100644
--- a/pkgs/development/python-modules/pycyphal/default.nix
+++ b/pkgs/development/python-modules/pycyphal/default.nix
@@ -56,7 +56,7 @@ buildPythonPackage rec {
     pytestCheckHook
     pytest-asyncio
   ]
-  ++ builtins.foldl' (x: y: x ++ y) [ ] (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   preCheck = ''
     export HOME=$TMPDIR
diff --git a/pkgs/development/python-modules/pydantic/1.nix b/pkgs/development/python-modules/pydantic/1.nix
index 40a02a959e62..da0ff4c6f6a6 100644
--- a/pkgs/development/python-modules/pydantic/1.nix
+++ b/pkgs/development/python-modules/pydantic/1.nix
@@ -51,7 +51,7 @@ buildPythonPackage rec {
     pytest7CheckHook
     writableTmpDirAsHomeHook
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   enableParallelBuilding = true;
 
diff --git a/pkgs/development/python-modules/pydantic/default.nix b/pkgs/development/python-modules/pydantic/default.nix
index 5f0d1c58efe6..ec6694213699 100644
--- a/pkgs/development/python-modules/pydantic/default.nix
+++ b/pkgs/development/python-modules/pydantic/default.nix
@@ -71,7 +71,7 @@ buildPythonPackage rec {
     pytestCheckHook
     rich
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies)
+  ++ lib.concatAttrValues optional-dependencies
   ++ lib.optionals (pythonOlder "3.10") [ eval-type-backport ];
 
   preCheck = ''
diff --git a/pkgs/development/python-modules/pydruid/default.nix b/pkgs/development/python-modules/pydruid/default.nix
index 9b4df9aaf703..b60ea009655d 100644
--- a/pkgs/development/python-modules/pydruid/default.nix
+++ b/pkgs/development/python-modules/pydruid/default.nix
@@ -42,7 +42,7 @@ buildPythonPackage rec {
     pytestCheckHook
     pycurl
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "pydruid" ];
 
diff --git a/pkgs/development/python-modules/pyecharts/default.nix b/pkgs/development/python-modules/pyecharts/default.nix
index 06f7db4eb268..b3d04bbfc070 100644
--- a/pkgs/development/python-modules/pyecharts/default.nix
+++ b/pkgs/development/python-modules/pyecharts/default.nix
@@ -46,7 +46,7 @@ buildPythonPackage rec {
     pytestCheckHook
     requests
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "pyecharts" ];
 
diff --git a/pkgs/development/python-modules/pygal/default.nix b/pkgs/development/python-modules/pygal/default.nix
index e6aeafc66b03..9912c2131dd7 100644
--- a/pkgs/development/python-modules/pygal/default.nix
+++ b/pkgs/development/python-modules/pygal/default.nix
@@ -50,7 +50,7 @@ buildPythonPackage rec {
     pyquery
     pytestCheckHook
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   preCheck = ''
     # necessary on darwin to pass the testsuite
diff --git a/pkgs/development/python-modules/pyhanko/default.nix b/pkgs/development/python-modules/pyhanko/default.nix
index 5d91680adc2b..9e7aaadbfe34 100644
--- a/pkgs/development/python-modules/pyhanko/default.nix
+++ b/pkgs/development/python-modules/pyhanko/default.nix
@@ -99,7 +99,7 @@ buildPythonPackage rec {
     passthru.testData
     signxml
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   disabledTestPaths = [
     # ModuleNotFoundError: No module named 'csc_dummy'
diff --git a/pkgs/development/python-modules/pyjwt/default.nix b/pkgs/development/python-modules/pyjwt/default.nix
index d4628b4466bb..ce6e51b99bbe 100644
--- a/pkgs/development/python-modules/pyjwt/default.nix
+++ b/pkgs/development/python-modules/pyjwt/default.nix
@@ -38,7 +38,7 @@ buildPythonPackage rec {
 
   optional-dependencies.crypto = [ cryptography ];
 
-  nativeCheckInputs = [ pytestCheckHook ] ++ (lib.flatten (lib.attrValues optional-dependencies));
+  nativeCheckInputs = [ pytestCheckHook ] ++ (lib.concatAttrValues optional-dependencies);
 
   disabledTests = [
     # requires internet connection
diff --git a/pkgs/development/python-modules/pymatgen/default.nix b/pkgs/development/python-modules/pymatgen/default.nix
index 4497c333346a..38f1a7e95e3c 100644
--- a/pkgs/development/python-modules/pymatgen/default.nix
+++ b/pkgs/development/python-modules/pymatgen/default.nix
@@ -127,7 +127,7 @@ buildPythonPackage rec {
     pytestCheckHook
     pytest-xdist
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   preCheck =
     # ensure tests can find these
diff --git a/pkgs/development/python-modules/pymbolic/default.nix b/pkgs/development/python-modules/pymbolic/default.nix
index 8be9ffbd8c0e..86f95d813991 100644
--- a/pkgs/development/python-modules/pymbolic/default.nix
+++ b/pkgs/development/python-modules/pymbolic/default.nix
@@ -44,7 +44,7 @@ buildPythonPackage rec {
     numpy = [ numpy ];
   };
 
-  nativeCheckInputs = [ pytestCheckHook ] ++ lib.flatten (builtins.attrValues optional-dependencies);
+  nativeCheckInputs = [ pytestCheckHook ] ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "pymbolic" ];
 
diff --git a/pkgs/development/python-modules/pymodbus/default.nix b/pkgs/development/python-modules/pymodbus/default.nix
index 1be0a2a6731c..292aac9fffea 100644
--- a/pkgs/development/python-modules/pymodbus/default.nix
+++ b/pkgs/development/python-modules/pymodbus/default.nix
@@ -50,7 +50,7 @@ buildPythonPackage rec {
     sqlalchemy
     twisted
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   preCheck = ''
     pushd test
diff --git a/pkgs/development/python-modules/pymorphy3/default.nix b/pkgs/development/python-modules/pymorphy3/default.nix
index a2273ea72efa..a14b16e5cf7e 100644
--- a/pkgs/development/python-modules/pymorphy3/default.nix
+++ b/pkgs/development/python-modules/pymorphy3/default.nix
@@ -47,7 +47,7 @@ buildPythonPackage rec {
   nativeCheckInputs = [
     pytestCheckHook
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "pymorphy3" ];
 
diff --git a/pkgs/development/python-modules/pynws/default.nix b/pkgs/development/python-modules/pynws/default.nix
index b9da7fcbceea..38013d15ea7b 100644
--- a/pkgs/development/python-modules/pynws/default.nix
+++ b/pkgs/development/python-modules/pynws/default.nix
@@ -48,7 +48,7 @@ buildPythonPackage rec {
     pytest-cov-stub
     pytestCheckHook
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "pynws" ];
 
diff --git a/pkgs/development/python-modules/pypiserver/default.nix b/pkgs/development/python-modules/pypiserver/default.nix
index 121801f3b9ac..bfa5c7d55902 100644
--- a/pkgs/development/python-modules/pypiserver/default.nix
+++ b/pkgs/development/python-modules/pypiserver/default.nix
@@ -57,7 +57,7 @@ buildPythonPackage rec {
     webtest
     build
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   __darwinAllowLocalNetworking = true;
 
diff --git a/pkgs/development/python-modules/pyproject-parser/default.nix b/pkgs/development/python-modules/pyproject-parser/default.nix
index 95a7a7e4c2c6..d05c1ca6fc1e 100644
--- a/pkgs/development/python-modules/pyproject-parser/default.nix
+++ b/pkgs/development/python-modules/pyproject-parser/default.nix
@@ -46,7 +46,7 @@ buildPythonPackage rec {
   ];
 
   optional-dependencies = {
-    all = lib.flatten (lib.attrValues (lib.removeAttrs optional-dependencies [ "all" ]));
+    all = lib.concatAttrValues (lib.removeAttrs optional-dependencies [ "all" ]);
     cli = [
       click
       consolekit
diff --git a/pkgs/development/python-modules/pyrate-limiter/default.nix b/pkgs/development/python-modules/pyrate-limiter/default.nix
index 95261eed47c2..fe0c175048fd 100644
--- a/pkgs/development/python-modules/pyrate-limiter/default.nix
+++ b/pkgs/development/python-modules/pyrate-limiter/default.nix
@@ -61,7 +61,7 @@ buildPythonPackage rec {
     pytest-xdist
     redisTestHook
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   disabledTestPaths = [
     # Slow: > 1.5 seconds/test run standalone on a fast machine
diff --git a/pkgs/development/python-modules/pytablewriter/default.nix b/pkgs/development/python-modules/pytablewriter/default.nix
index 7b638dd962da..99043a10cf4e 100644
--- a/pkgs/development/python-modules/pytablewriter/default.nix
+++ b/pkgs/development/python-modules/pytablewriter/default.nix
@@ -85,7 +85,7 @@ buildPythonPackage rec {
   nativeCheckInputs = [
     pytestCheckHook
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "pathvalidate" ];
 
diff --git a/pkgs/development/python-modules/pytest-aio/default.nix b/pkgs/development/python-modules/pytest-aio/default.nix
index d70e7bf6495c..8216ac5e5075 100644
--- a/pkgs/development/python-modules/pytest-aio/default.nix
+++ b/pkgs/development/python-modules/pytest-aio/default.nix
@@ -44,7 +44,7 @@ buildPythonPackage rec {
     pytestCheckHook
     trio-asyncio
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "pytest_aio" ];
 
diff --git a/pkgs/development/python-modules/pytest-benchmark/default.nix b/pkgs/development/python-modules/pytest-benchmark/default.nix
index 1b14abd0d189..065649d70b48 100644
--- a/pkgs/development/python-modules/pytest-benchmark/default.nix
+++ b/pkgs/development/python-modules/pytest-benchmark/default.nix
@@ -56,7 +56,7 @@ buildPythonPackage rec {
     nbmake
     pytestCheckHook
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   preCheck = ''
     export PATH="$out/bin:$PATH"
diff --git a/pkgs/development/python-modules/pytest-jupyter/default.nix b/pkgs/development/python-modules/pytest-jupyter/default.nix
index 041d29b89d2f..671c0f865a79 100644
--- a/pkgs/development/python-modules/pytest-jupyter/default.nix
+++ b/pkgs/development/python-modules/pytest-jupyter/default.nix
@@ -60,7 +60,7 @@ let
       pytest-timeout
       pytestCheckHook
     ]
-    ++ lib.flatten (builtins.attrValues optional-dependencies);
+    ++ lib.concatAttrValues optional-dependencies;
 
     passthru.tests = {
       check = self.overridePythonAttrs (_: {
diff --git a/pkgs/development/python-modules/pytest-regressions/default.nix b/pkgs/development/python-modules/pytest-regressions/default.nix
index ac36a4ae5657..13c0f38a506a 100644
--- a/pkgs/development/python-modules/pytest-regressions/default.nix
+++ b/pkgs/development/python-modules/pytest-regressions/default.nix
@@ -58,7 +58,7 @@ buildPythonPackage rec {
     pandas
     pytestCheckHook
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pytestFlags = [
     "-Wignore::DeprecationWarning"
diff --git a/pkgs/development/python-modules/pytest-variables/default.nix b/pkgs/development/python-modules/pytest-variables/default.nix
index 84e628e00a5f..ad438b6eb44c 100644
--- a/pkgs/development/python-modules/pytest-variables/default.nix
+++ b/pkgs/development/python-modules/pytest-variables/default.nix
@@ -39,7 +39,7 @@ buildPythonPackage rec {
     yaml = [ pyyaml ];
   };
 
-  nativeCheckInputs = [ pytestCheckHook ] ++ lib.flatten (builtins.attrValues optional-dependencies);
+  nativeCheckInputs = [ pytestCheckHook ] ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "pytest_variables" ];
 
diff --git a/pkgs/development/python-modules/python-benedict/default.nix b/pkgs/development/python-modules/python-benedict/default.nix
index e6f648e91ce1..225e24a69cfa 100644
--- a/pkgs/development/python-modules/python-benedict/default.nix
+++ b/pkgs/development/python-modules/python-benedict/default.nix
@@ -93,7 +93,7 @@ buildPythonPackage rec {
     pytestCheckHook
     python-decouple
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   disabledTests = [
     # Tests require network access
diff --git a/pkgs/development/python-modules/python-dali/default.nix b/pkgs/development/python-modules/python-dali/default.nix
index 1ac761317224..d527252626bb 100644
--- a/pkgs/development/python-modules/python-dali/default.nix
+++ b/pkgs/development/python-modules/python-dali/default.nix
@@ -45,7 +45,7 @@ buildPythonPackage rec {
     pytestCheckHook
     pytest-asyncio
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "dali" ];
 
diff --git a/pkgs/development/python-modules/python-engineio/default.nix b/pkgs/development/python-modules/python-engineio/default.nix
index fb0b279437df..788c1d5e06c4 100644
--- a/pkgs/development/python-modules/python-engineio/default.nix
+++ b/pkgs/development/python-modules/python-engineio/default.nix
@@ -49,7 +49,7 @@ buildPythonPackage rec {
     pytest-asyncio
     pytestCheckHook
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   preCheck = lib.optionalString stdenv.hostPlatform.isLinux ''
     echo "nameserver 127.0.0.1" > resolv.conf
diff --git a/pkgs/development/python-modules/python-jose/default.nix b/pkgs/development/python-modules/python-jose/default.nix
index 539d1e5644bb..d4f2093c2a3c 100644
--- a/pkgs/development/python-modules/python-jose/default.nix
+++ b/pkgs/development/python-modules/python-jose/default.nix
@@ -54,7 +54,7 @@ buildPythonPackage rec {
   nativeCheckInputs = [
     pytestCheckHook
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "jose" ];
 
diff --git a/pkgs/development/python-modules/python-matter-server/default.nix b/pkgs/development/python-modules/python-matter-server/default.nix
index cd72b8277920..811cebe76442 100644
--- a/pkgs/development/python-modules/python-matter-server/default.nix
+++ b/pkgs/development/python-modules/python-matter-server/default.nix
@@ -166,7 +166,7 @@ buildPythonPackage rec {
     pytest-cov-stub
     pytestCheckHook
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   preCheck =
     let
diff --git a/pkgs/development/python-modules/python-socketio/default.nix b/pkgs/development/python-modules/python-socketio/default.nix
index ce1e23763ffa..8220ee89a803 100644
--- a/pkgs/development/python-modules/python-socketio/default.nix
+++ b/pkgs/development/python-modules/python-socketio/default.nix
@@ -63,7 +63,7 @@ buildPythonPackage rec {
     valkey
     pytest-asyncio
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "socketio" ];
 
diff --git a/pkgs/development/python-modules/pythonfinder/default.nix b/pkgs/development/python-modules/pythonfinder/default.nix
index 5643a946d6d5..6733bbf21688 100644
--- a/pkgs/development/python-modules/pythonfinder/default.nix
+++ b/pkgs/development/python-modules/pythonfinder/default.nix
@@ -39,7 +39,7 @@ buildPythonPackage rec {
     pytest-timeout
     pytestCheckHook
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "pythonfinder" ];
 
diff --git a/pkgs/development/python-modules/pytoolconfig/default.nix b/pkgs/development/python-modules/pytoolconfig/default.nix
index 66dc7b7c977f..cd7d3a6c8b5b 100644
--- a/pkgs/development/python-modules/pytoolconfig/default.nix
+++ b/pkgs/development/python-modules/pytoolconfig/default.nix
@@ -65,7 +65,7 @@ buildPythonPackage rec {
   nativeCheckInputs = [
     pytestCheckHook
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   meta = with lib; {
     description = "Python tool configuration";
diff --git a/pkgs/development/python-modules/pytorch-metric-learning/default.nix b/pkgs/development/python-modules/pytorch-metric-learning/default.nix
index f48157cae2a5..374889c3bf6c 100644
--- a/pkgs/development/python-modules/pytorch-metric-learning/default.nix
+++ b/pkgs/development/python-modules/pytorch-metric-learning/default.nix
@@ -73,7 +73,7 @@ buildPythonPackage rec {
     torchvision
     writableTmpDirAsHomeHook
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   disabledTests = [
     # network access
diff --git a/pkgs/development/python-modules/pyutil/default.nix b/pkgs/development/python-modules/pyutil/default.nix
index 37d9751db3ce..f89c26c73b2b 100644
--- a/pkgs/development/python-modules/pyutil/default.nix
+++ b/pkgs/development/python-modules/pyutil/default.nix
@@ -47,7 +47,7 @@ buildPythonPackage rec {
     twisted
     pytestCheckHook
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "pyutil" ];
 
diff --git a/pkgs/development/python-modules/pywinrm/default.nix b/pkgs/development/python-modules/pywinrm/default.nix
index b8c8880225b9..fe213f4d6b5b 100644
--- a/pkgs/development/python-modules/pywinrm/default.nix
+++ b/pkgs/development/python-modules/pywinrm/default.nix
@@ -42,7 +42,7 @@ buildPythonPackage rec {
     mock
     pytestCheckHook
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "winrm" ];
 
diff --git a/pkgs/development/python-modules/qcelemental/default.nix b/pkgs/development/python-modules/qcelemental/default.nix
index 36a258c0ff59..ba603c58dcc8 100644
--- a/pkgs/development/python-modules/qcelemental/default.nix
+++ b/pkgs/development/python-modules/qcelemental/default.nix
@@ -47,7 +47,7 @@ buildPythonPackage rec {
     ];
   };
 
-  nativeCheckInputs = [ pytestCheckHook ] ++ lib.flatten (lib.attrValues optional-dependencies);
+  nativeCheckInputs = [ pytestCheckHook ] ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "qcelemental" ];
 
diff --git a/pkgs/development/python-modules/qcengine/default.nix b/pkgs/development/python-modules/qcengine/default.nix
index 8b36477d2342..6b282a19f826 100644
--- a/pkgs/development/python-modules/qcengine/default.nix
+++ b/pkgs/development/python-modules/qcengine/default.nix
@@ -50,7 +50,7 @@ buildPythonPackage rec {
     ];
   };
 
-  nativeCheckInputs = [ pytestCheckHook ] ++ lib.flatten (builtins.attrValues optional-dependencies);
+  nativeCheckInputs = [ pytestCheckHook ] ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "qcengine" ];
 
diff --git a/pkgs/development/python-modules/qrcode/default.nix b/pkgs/development/python-modules/qrcode/default.nix
index 4aeda018a902..bc1bd5b86a4d 100644
--- a/pkgs/development/python-modules/qrcode/default.nix
+++ b/pkgs/development/python-modules/qrcode/default.nix
@@ -45,7 +45,7 @@ buildPythonPackage rec {
     mock
     pytestCheckHook
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   passthru.tests = {
     version = testers.testVersion {
diff --git a/pkgs/development/python-modules/qutip/default.nix b/pkgs/development/python-modules/qutip/default.nix
index 548b77f632ef..0df9b6176396 100644
--- a/pkgs/development/python-modules/qutip/default.nix
+++ b/pkgs/development/python-modules/qutip/default.nix
@@ -63,7 +63,7 @@ buildPythonPackage rec {
     pytest-rerunfailures
     writableTmpDirAsHomeHook
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   # QuTiP tries to access the home directory to create an rc file for us.
   # We need to go to another directory to run the tests from there.
diff --git a/pkgs/development/python-modules/ratarmountcore/default.nix b/pkgs/development/python-modules/ratarmountcore/default.nix
index c0d4e5c06dc0..2f98dc739350 100644
--- a/pkgs/development/python-modules/ratarmountcore/default.nix
+++ b/pkgs/development/python-modules/ratarmountcore/default.nix
@@ -59,7 +59,7 @@ buildPythonPackage rec {
     fsspec
     writableTmpDirAsHomeHook
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "ratarmountcore" ];
 
diff --git a/pkgs/development/python-modules/renault-api/default.nix b/pkgs/development/python-modules/renault-api/default.nix
index 73db03afa62e..de173f0fb5db 100644
--- a/pkgs/development/python-modules/renault-api/default.nix
+++ b/pkgs/development/python-modules/renault-api/default.nix
@@ -53,7 +53,7 @@ buildPythonPackage rec {
     syrupy
     typeguard
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "renault_api" ];
 
diff --git a/pkgs/development/python-modules/reptor/default.nix b/pkgs/development/python-modules/reptor/default.nix
index e972155efcf3..ba400831c462 100644
--- a/pkgs/development/python-modules/reptor/default.nix
+++ b/pkgs/development/python-modules/reptor/default.nix
@@ -70,7 +70,7 @@ buildPythonPackage rec {
   nativeCheckInputs = [
     pytestCheckHook
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   preCheck = ''
     export PATH="$PATH:$out/bin";
diff --git a/pkgs/development/python-modules/sagemaker-core/default.nix b/pkgs/development/python-modules/sagemaker-core/default.nix
index 7a5464948fd0..1c305cde20b1 100644
--- a/pkgs/development/python-modules/sagemaker-core/default.nix
+++ b/pkgs/development/python-modules/sagemaker-core/default.nix
@@ -76,7 +76,7 @@ buildPythonPackage rec {
   nativeCheckInputs = [
     pytestCheckHook
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   disabledTestPaths = [
     # Tries to import deprecated `sklearn`
diff --git a/pkgs/development/python-modules/scholarly/default.nix b/pkgs/development/python-modules/scholarly/default.nix
index 39f24bbc2781..47ddaed6e059 100644
--- a/pkgs/development/python-modules/scholarly/default.nix
+++ b/pkgs/development/python-modules/scholarly/default.nix
@@ -55,7 +55,7 @@ buildPythonPackage rec {
     tor = [ stem ];
   };
 
-  nativeCheckInputs = lib.flatten (lib.attrValues optional-dependencies);
+  nativeCheckInputs = lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "scholarly" ];
 
diff --git a/pkgs/development/python-modules/schwifty/default.nix b/pkgs/development/python-modules/schwifty/default.nix
index 28c8c1ab9a4d..b53318bf2ae8 100644
--- a/pkgs/development/python-modules/schwifty/default.nix
+++ b/pkgs/development/python-modules/schwifty/default.nix
@@ -52,7 +52,7 @@ buildPythonPackage rec {
   nativeCheckInputs = [
     pytestCheckHook
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "schwifty" ];
 
diff --git a/pkgs/development/python-modules/seabreeze/default.nix b/pkgs/development/python-modules/seabreeze/default.nix
index 976382e408b9..1c5972d3144c 100644
--- a/pkgs/development/python-modules/seabreeze/default.nix
+++ b/pkgs/development/python-modules/seabreeze/default.nix
@@ -80,7 +80,7 @@ buildPythonPackage rec {
     mock
     zipp
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   disabledTests = [ "TestHardware" ];
 
diff --git a/pkgs/development/python-modules/seasonal/default.nix b/pkgs/development/python-modules/seasonal/default.nix
index c3810c8e0610..2f24a5a96417 100644
--- a/pkgs/development/python-modules/seasonal/default.nix
+++ b/pkgs/development/python-modules/seasonal/default.nix
@@ -52,7 +52,7 @@ buildPythonPackage rec {
   nativeCheckInputs = [
     pytestCheckHook
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   meta = with lib; {
     description = "Robustly estimate trend and periodicity in a timeseries";
diff --git a/pkgs/development/python-modules/securesystemslib/default.nix b/pkgs/development/python-modules/securesystemslib/default.nix
index 82507b6b6623..b31f840d1163 100644
--- a/pkgs/development/python-modules/securesystemslib/default.nix
+++ b/pkgs/development/python-modules/securesystemslib/default.nix
@@ -66,7 +66,7 @@ buildPythonPackage rec {
     ed25519
     pytestCheckHook
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "securesystemslib" ];
 
diff --git a/pkgs/development/python-modules/sentence-transformers/default.nix b/pkgs/development/python-modules/sentence-transformers/default.nix
index 0e63b52faee1..dde406954171 100644
--- a/pkgs/development/python-modules/sentence-transformers/default.nix
+++ b/pkgs/development/python-modules/sentence-transformers/default.nix
@@ -64,7 +64,7 @@ buildPythonPackage rec {
     pytest-cov-stub
     pytestCheckHook
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "sentence_transformers" ];
 
diff --git a/pkgs/development/python-modules/sfrbox-api/default.nix b/pkgs/development/python-modules/sfrbox-api/default.nix
index c65e60a4edc9..cf5e50c40c18 100644
--- a/pkgs/development/python-modules/sfrbox-api/default.nix
+++ b/pkgs/development/python-modules/sfrbox-api/default.nix
@@ -41,7 +41,7 @@ buildPythonPackage rec {
     pytest-asyncio
     pytestCheckHook
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "sfrbox_api" ];
 
diff --git a/pkgs/development/python-modules/shiny/default.nix b/pkgs/development/python-modules/shiny/default.nix
index 88d3b9137486..212febd293b8 100644
--- a/pkgs/development/python-modules/shiny/default.nix
+++ b/pkgs/development/python-modules/shiny/default.nix
@@ -110,7 +110,7 @@ buildPythonPackage rec {
     pytest-xdist
     pytestCheckHook
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pytestFlags = [
     # ERROR: 'fixture' is not a valid asyncio_default_fixture_loop_scope.
diff --git a/pkgs/development/python-modules/shinychat/default.nix b/pkgs/development/python-modules/shinychat/default.nix
index 851247d54448..8239e37249f6 100644
--- a/pkgs/development/python-modules/shinychat/default.nix
+++ b/pkgs/development/python-modules/shinychat/default.nix
@@ -78,7 +78,7 @@ buildPythonPackage rec {
     pytestCheckHook
     shiny
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   disabledTests = [
     # AssertionError: assert False
diff --git a/pkgs/development/python-modules/simpful/default.nix b/pkgs/development/python-modules/simpful/default.nix
index 83851f0ec788..f86ad67a28dc 100644
--- a/pkgs/development/python-modules/simpful/default.nix
+++ b/pkgs/development/python-modules/simpful/default.nix
@@ -45,7 +45,7 @@ buildPythonPackage rec {
   nativeCheckInputs = [
     pytestCheckHook
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "simpful" ];
 
diff --git a/pkgs/development/python-modules/slack-bolt/default.nix b/pkgs/development/python-modules/slack-bolt/default.nix
index 2710dc01ebb3..b53f724fde10 100644
--- a/pkgs/development/python-modules/slack-bolt/default.nix
+++ b/pkgs/development/python-modules/slack-bolt/default.nix
@@ -89,7 +89,7 @@ buildPythonPackage rec {
     pytestCheckHook
     writableTmpDirAsHomeHook
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   __darwinAllowLocalNetworking = true;
 
diff --git a/pkgs/development/python-modules/slixmpp/default.nix b/pkgs/development/python-modules/slixmpp/default.nix
index ee478927da57..6b94d9f3930b 100644
--- a/pkgs/development/python-modules/slixmpp/default.nix
+++ b/pkgs/development/python-modules/slixmpp/default.nix
@@ -54,7 +54,7 @@ buildPythonPackage rec {
     safer-xml-parserig = [ defusedxml ];
   };
 
-  nativeCheckInputs = [ pytestCheckHook ] ++ lib.flatten (lib.attrValues optional-dependencies);
+  nativeCheckInputs = [ pytestCheckHook ] ++ lib.concatAttrValues optional-dependencies;
 
   preCheck = ''
     # don't test against pure python version in the source tree
diff --git a/pkgs/development/python-modules/smart-open/default.nix b/pkgs/development/python-modules/smart-open/default.nix
index 4a3e57accea5..d4a6d8e7723a 100644
--- a/pkgs/development/python-modules/smart-open/default.nix
+++ b/pkgs/development/python-modules/smart-open/default.nix
@@ -70,7 +70,7 @@ buildPythonPackage rec {
     responses
   ]
   ++ moto.optional-dependencies.server
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   enabledTestPaths = [ "tests" ];
 
diff --git a/pkgs/development/python-modules/smolagents/default.nix b/pkgs/development/python-modules/smolagents/default.nix
index 651f53a55a50..174d4313b5be 100644
--- a/pkgs/development/python-modules/smolagents/default.nix
+++ b/pkgs/development/python-modules/smolagents/default.nix
@@ -128,7 +128,7 @@ buildPythonPackage rec {
     pytestCheckHook
     wikipedia-api
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "smolagents" ];
 
diff --git a/pkgs/development/python-modules/social-auth-core/default.nix b/pkgs/development/python-modules/social-auth-core/default.nix
index 3da2e57c455f..994433501dcd 100644
--- a/pkgs/development/python-modules/social-auth-core/default.nix
+++ b/pkgs/development/python-modules/social-auth-core/default.nix
@@ -63,7 +63,7 @@ buildPythonPackage rec {
     responses
     typing-extensions
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   disabledTestPaths = [
     # missing google-auth-stubs
diff --git a/pkgs/development/python-modules/speechrecognition/default.nix b/pkgs/development/python-modules/speechrecognition/default.nix
index 4140e605a32b..41afd46d3628 100644
--- a/pkgs/development/python-modules/speechrecognition/default.nix
+++ b/pkgs/development/python-modules/speechrecognition/default.nix
@@ -78,7 +78,7 @@ buildPythonPackage rec {
     pocketsphinx
     respx
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "speech_recognition" ];
 
diff --git a/pkgs/development/python-modules/splinter/default.nix b/pkgs/development/python-modules/splinter/default.nix
index b63e1876e002..20aee8a7bab3 100644
--- a/pkgs/development/python-modules/splinter/default.nix
+++ b/pkgs/development/python-modules/splinter/default.nix
@@ -55,7 +55,7 @@ buildPythonPackage rec {
   nativeCheckInputs = [
     pytestCheckHook
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   disabledTests = [
     # driver is present and fails with a different error during loading
diff --git a/pkgs/development/python-modules/sqlalchemy-utils/default.nix b/pkgs/development/python-modules/sqlalchemy-utils/default.nix
index 8062a08fea5a..abde2fbec857 100644
--- a/pkgs/development/python-modules/sqlalchemy-utils/default.nix
+++ b/pkgs/development/python-modules/sqlalchemy-utils/default.nix
@@ -75,7 +75,7 @@ buildPythonPackage rec {
     pymysql
     pyodbc
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies)
+  ++ lib.concatAttrValues optional-dependencies
   ++ lib.optionals (pythonOlder "3.12") [
     # requires distutils, which were removed in 3.12
     psycopg2cffi
diff --git a/pkgs/development/python-modules/sqlfmt/default.nix b/pkgs/development/python-modules/sqlfmt/default.nix
index da67f58c661d..84d8df135054 100644
--- a/pkgs/development/python-modules/sqlfmt/default.nix
+++ b/pkgs/development/python-modules/sqlfmt/default.nix
@@ -65,7 +65,7 @@ buildPythonPackage rec {
     versionCheckHook
     writableTmpDirAsHomeHook
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
   versionCheckProgramArg = "--version";
 
   disabledTestPaths = [
diff --git a/pkgs/development/python-modules/sqlframe/default.nix b/pkgs/development/python-modules/sqlframe/default.nix
index 07c5ae20ed3e..d9ef407e6dcd 100644
--- a/pkgs/development/python-modules/sqlframe/default.nix
+++ b/pkgs/development/python-modules/sqlframe/default.nix
@@ -83,7 +83,7 @@ buildPythonPackage rec {
     pytest-xdist
     pytestCheckHook
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   disabledTests = [
     # Requires google-cloud credentials
diff --git a/pkgs/development/python-modules/starlette/default.nix b/pkgs/development/python-modules/starlette/default.nix
index c327f0bf46db..e8e2b425502d 100644
--- a/pkgs/development/python-modules/starlette/default.nix
+++ b/pkgs/development/python-modules/starlette/default.nix
@@ -57,7 +57,7 @@ buildPythonPackage rec {
     trio
     typing-extensions
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pytestFlags = [
     "-Wignore::DeprecationWarning"
diff --git a/pkgs/development/python-modules/static3/default.nix b/pkgs/development/python-modules/static3/default.nix
index 607acca24a8a..7322921cfd78 100644
--- a/pkgs/development/python-modules/static3/default.nix
+++ b/pkgs/development/python-modules/static3/default.nix
@@ -41,7 +41,7 @@ buildPythonPackage rec {
     pytestCheckHook
     webtest
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   meta = with lib; {
     changelog = "https://github.com/rmohr/static3/releases/tag/v${version}";
diff --git a/pkgs/development/python-modules/stm32loader/default.nix b/pkgs/development/python-modules/stm32loader/default.nix
index 9a0e437cb365..79d37c51868b 100644
--- a/pkgs/development/python-modules/stm32loader/default.nix
+++ b/pkgs/development/python-modules/stm32loader/default.nix
@@ -51,7 +51,7 @@ buildPythonPackage rec {
   nativeCheckInputs = [
     pytestCheckHook
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   enabledTestPaths = [ "tests/unit" ];
 
diff --git a/pkgs/development/python-modules/strawberry-graphql/default.nix b/pkgs/development/python-modules/strawberry-graphql/default.nix
index 7378ba44d71b..82794502341c 100644
--- a/pkgs/development/python-modules/strawberry-graphql/default.nix
+++ b/pkgs/development/python-modules/strawberry-graphql/default.nix
@@ -139,7 +139,7 @@ buildPythonPackage rec {
     pytestCheckHook
     sanic-testing
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "strawberry" ];
 
diff --git a/pkgs/development/python-modules/tabulate/default.nix b/pkgs/development/python-modules/tabulate/default.nix
index ac3450f87e1e..b9df2fc2bfda 100644
--- a/pkgs/development/python-modules/tabulate/default.nix
+++ b/pkgs/development/python-modules/tabulate/default.nix
@@ -33,7 +33,7 @@ buildPythonPackage rec {
   nativeCheckInputs = [
     pytestCheckHook
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   meta = {
     description = "Pretty-print tabular data";
diff --git a/pkgs/development/python-modules/textual-fastdatatable/default.nix b/pkgs/development/python-modules/textual-fastdatatable/default.nix
index 714cb97fd954..dcbdece94343 100644
--- a/pkgs/development/python-modules/textual-fastdatatable/default.nix
+++ b/pkgs/development/python-modules/textual-fastdatatable/default.nix
@@ -47,7 +47,7 @@ buildPythonPackage rec {
     pytest-textual-snapshot
     pytestCheckHook
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "textual_fastdatatable" ];
 
diff --git a/pkgs/development/python-modules/tianshou/default.nix b/pkgs/development/python-modules/tianshou/default.nix
index 2012e3f360a9..a63bb89cd38e 100644
--- a/pkgs/development/python-modules/tianshou/default.nix
+++ b/pkgs/development/python-modules/tianshou/default.nix
@@ -92,7 +92,7 @@ buildPythonPackage rec {
   ];
 
   optional-dependencies = {
-    all = lib.flatten (lib.attrValues (lib.removeAttrs optional-dependencies [ "all" ]));
+    all = lib.concatAttrValues (lib.removeAttrs optional-dependencies [ "all" ]);
 
     argparse = [
       docstring-parser
diff --git a/pkgs/development/python-modules/timezonefinder/default.nix b/pkgs/development/python-modules/timezonefinder/default.nix
index 5f72859975a4..f530fe5d4d68 100644
--- a/pkgs/development/python-modules/timezonefinder/default.nix
+++ b/pkgs/development/python-modules/timezonefinder/default.nix
@@ -45,7 +45,7 @@ buildPythonPackage rec {
     pydantic
     pytestCheckHook
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "timezonefinder" ];
 
diff --git a/pkgs/development/python-modules/trino-python-client/default.nix b/pkgs/development/python-modules/trino-python-client/default.nix
index 16756d0b36b3..7c8373fa7e70 100644
--- a/pkgs/development/python-modules/trino-python-client/default.nix
+++ b/pkgs/development/python-modules/trino-python-client/default.nix
@@ -56,7 +56,7 @@ buildPythonPackage rec {
     pytestCheckHook
     testcontainers
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "trino" ];
 
diff --git a/pkgs/development/python-modules/tweepy/default.nix b/pkgs/development/python-modules/tweepy/default.nix
index 975136a2fec9..ca53304e13c8 100644
--- a/pkgs/development/python-modules/tweepy/default.nix
+++ b/pkgs/development/python-modules/tweepy/default.nix
@@ -43,7 +43,7 @@ buildPythonPackage rec {
     pytestCheckHook
     vcrpy
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "tweepy" ];
 
diff --git a/pkgs/development/python-modules/typed-settings/default.nix b/pkgs/development/python-modules/typed-settings/default.nix
index 78802f283b33..1e8aa9034473 100644
--- a/pkgs/development/python-modules/typed-settings/default.nix
+++ b/pkgs/development/python-modules/typed-settings/default.nix
@@ -66,7 +66,7 @@ buildPythonPackage rec {
     sybil
   ]
   ++ (lib.optional (pythonOlder "3.11") typing-extensions)
-  ++ (lib.flatten (lib.attrValues optional-dependencies));
+  ++ (lib.concatAttrValues optional-dependencies);
 
   enabledTestPaths = [ "tests" ];
 
diff --git a/pkgs/development/python-modules/typepy/default.nix b/pkgs/development/python-modules/typepy/default.nix
index c4979dc6ac86..96bb30d4db6f 100644
--- a/pkgs/development/python-modules/typepy/default.nix
+++ b/pkgs/development/python-modules/typepy/default.nix
@@ -42,7 +42,7 @@ buildPythonPackage rec {
     pytestCheckHook
     tcolorpy
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "typepy" ];
 
diff --git a/pkgs/development/python-modules/types-lxml/default.nix b/pkgs/development/python-modules/types-lxml/default.nix
index d54e01fc1629..7f1af2a0db47 100644
--- a/pkgs/development/python-modules/types-lxml/default.nix
+++ b/pkgs/development/python-modules/types-lxml/default.nix
@@ -56,7 +56,7 @@ buildPythonPackage rec {
     typeguard
     urllib3
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "lxml-stubs" ];
 
diff --git a/pkgs/development/python-modules/ufmt/default.nix b/pkgs/development/python-modules/ufmt/default.nix
index 8215f457ab54..66fd09da6dab 100644
--- a/pkgs/development/python-modules/ufmt/default.nix
+++ b/pkgs/development/python-modules/ufmt/default.nix
@@ -59,7 +59,7 @@ buildPythonPackage rec {
     unittestCheckHook
     versionCheckHook
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
   versionCheckProgramArg = "--version";
 
   pythonImportsCheck = [ "ufmt" ];
diff --git a/pkgs/development/python-modules/ufolib2/default.nix b/pkgs/development/python-modules/ufolib2/default.nix
index 6d6ab0af094c..788bc9a1b799 100644
--- a/pkgs/development/python-modules/ufolib2/default.nix
+++ b/pkgs/development/python-modules/ufolib2/default.nix
@@ -50,7 +50,7 @@ buildPythonPackage rec {
   nativeCheckInputs = [
     pytestCheckHook
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "ufoLib2" ];
 
diff --git a/pkgs/development/python-modules/upcloud-api/default.nix b/pkgs/development/python-modules/upcloud-api/default.nix
index 3042ab22cb68..d6e6a0241d5b 100644
--- a/pkgs/development/python-modules/upcloud-api/default.nix
+++ b/pkgs/development/python-modules/upcloud-api/default.nix
@@ -33,7 +33,7 @@ buildPythonPackage rec {
     pytestCheckHook
     responses
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "upcloud_api" ];
 
diff --git a/pkgs/development/python-modules/uplink/default.nix b/pkgs/development/python-modules/uplink/default.nix
index 4020d8e0b9d5..b63878a65280 100644
--- a/pkgs/development/python-modules/uplink/default.nix
+++ b/pkgs/development/python-modules/uplink/default.nix
@@ -50,7 +50,7 @@ buildPythonPackage rec {
     pytest-asyncio
     pytest-twisted
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "uplink" ];
 
diff --git a/pkgs/development/python-modules/urllib3-future/default.nix b/pkgs/development/python-modules/urllib3-future/default.nix
index b431f2c6a46f..ab11fb8ad1f3 100644
--- a/pkgs/development/python-modules/urllib3-future/default.nix
+++ b/pkgs/development/python-modules/urllib3-future/default.nix
@@ -73,7 +73,7 @@ buildPythonPackage rec {
     tornado
     trustme
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   disabledTestPaths = [
     # test connects to the internet
diff --git a/pkgs/development/python-modules/urllib3/default.nix b/pkgs/development/python-modules/urllib3/default.nix
index 8a98c2c5bd59..cdb50f45df0d 100644
--- a/pkgs/development/python-modules/urllib3/default.nix
+++ b/pkgs/development/python-modules/urllib3/default.nix
@@ -54,7 +54,7 @@ let
       tornado
       trustme
     ]
-    ++ lib.flatten (builtins.attrValues optional-dependencies);
+    ++ lib.concatAttrValues optional-dependencies;
 
     # Tests in urllib3 are mostly timeout-based instead of event-based and
     # are therefore inherently flaky. On your own machine, the tests will
diff --git a/pkgs/development/python-modules/urwid/default.nix b/pkgs/development/python-modules/urwid/default.nix
index 464b2609fd7d..728bd4f5834d 100644
--- a/pkgs/development/python-modules/urwid/default.nix
+++ b/pkgs/development/python-modules/urwid/default.nix
@@ -63,7 +63,7 @@ buildPythonPackage rec {
     glibcLocales
     pytestCheckHook
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   env.LC_ALL = "en_US.UTF8";
 
diff --git a/pkgs/development/python-modules/validators/default.nix b/pkgs/development/python-modules/validators/default.nix
index 079ff89d4049..59b1177247f6 100644
--- a/pkgs/development/python-modules/validators/default.nix
+++ b/pkgs/development/python-modules/validators/default.nix
@@ -28,7 +28,7 @@ buildPythonPackage rec {
     crypto-eth-addresses = [ eth-hash ] ++ eth-hash.optional-dependencies.pycryptodome;
   };
 
-  nativeCheckInputs = [ pytestCheckHook ] ++ lib.flatten (lib.attrValues optional-dependencies);
+  nativeCheckInputs = [ pytestCheckHook ] ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "validators" ];
 
diff --git a/pkgs/development/python-modules/valkey/default.nix b/pkgs/development/python-modules/valkey/default.nix
index 6c17fcf919a6..793104f20e05 100644
--- a/pkgs/development/python-modules/valkey/default.nix
+++ b/pkgs/development/python-modules/valkey/default.nix
@@ -74,7 +74,7 @@ buildPythonPackage rec {
     ujson
     uvloop
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   disabledTestMarks = [
     "onlycluster"
diff --git a/pkgs/development/python-modules/visions/default.nix b/pkgs/development/python-modules/visions/default.nix
index 66e0364944c1..c922b0be801b 100644
--- a/pkgs/development/python-modules/visions/default.nix
+++ b/pkgs/development/python-modules/visions/default.nix
@@ -65,7 +65,7 @@ buildPythonPackage rec {
   nativeCheckInputs = [
     pytestCheckHook
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   disabledTests = [
     # TypeError: Converting `np.inexact` or `np.floating` to a dtype not allowed
diff --git a/pkgs/development/python-modules/w1thermsensor/default.nix b/pkgs/development/python-modules/w1thermsensor/default.nix
index 4a417f3e8a79..5d7ebfbccb0f 100644
--- a/pkgs/development/python-modules/w1thermsensor/default.nix
+++ b/pkgs/development/python-modules/w1thermsensor/default.nix
@@ -45,7 +45,7 @@ buildPythonPackage rec {
     pytestCheckHook
   ]
   ++ lib.optionals (pythonOlder "3.11") [ tomli ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "w1thermsensor" ];
 
diff --git a/pkgs/development/python-modules/watermark/default.nix b/pkgs/development/python-modules/watermark/default.nix
index 569b9d02bdc7..e82744029dd8 100644
--- a/pkgs/development/python-modules/watermark/default.nix
+++ b/pkgs/development/python-modules/watermark/default.nix
@@ -38,7 +38,7 @@ buildPythonPackage rec {
   nativeCheckInputs = [
     pytestCheckHook
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "watermark" ];
 
diff --git a/pkgs/development/python-modules/werkzeug/default.nix b/pkgs/development/python-modules/werkzeug/default.nix
index 70829aecb81a..785f57e3ca41 100644
--- a/pkgs/development/python-modules/werkzeug/default.nix
+++ b/pkgs/development/python-modules/werkzeug/default.nix
@@ -53,7 +53,7 @@ buildPythonPackage rec {
     pytest-timeout
     pytestCheckHook
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "werkzeug" ];
 
diff --git a/pkgs/development/python-modules/whey/default.nix b/pkgs/development/python-modules/whey/default.nix
index e07c68a3a423..415bd2a09023 100644
--- a/pkgs/development/python-modules/whey/default.nix
+++ b/pkgs/development/python-modules/whey/default.nix
@@ -55,7 +55,7 @@ buildPythonPackage rec {
   pythonImportsCheck = [ "whey" ];
 
   optional-dependencies = {
-    all = lib.flatten (lib.attrValues (lib.removeAttrs optional-dependencies [ "all" ]));
+    all = lib.concatAttrValues (lib.removeAttrs optional-dependencies [ "all" ]);
     editable = [
       editables
     ];
diff --git a/pkgs/development/python-modules/wtforms/default.nix b/pkgs/development/python-modules/wtforms/default.nix
index 5e1043684687..897ee3662898 100644
--- a/pkgs/development/python-modules/wtforms/default.nix
+++ b/pkgs/development/python-modules/wtforms/default.nix
@@ -48,7 +48,7 @@ buildPythonPackage rec {
   nativeCheckInputs = [
     pytestCheckHook
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "wtforms" ];
 
diff --git a/pkgs/development/python-modules/wyoming/default.nix b/pkgs/development/python-modules/wyoming/default.nix
index 763157aabb28..1caedfb360a1 100644
--- a/pkgs/development/python-modules/wyoming/default.nix
+++ b/pkgs/development/python-modules/wyoming/default.nix
@@ -47,7 +47,7 @@ buildPythonPackage rec {
     pytest-asyncio
     pytestCheckHook
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   passthru.tests = {
     inherit wyoming-faster-whisper wyoming-openwakeword wyoming-piper;
diff --git a/pkgs/development/python-modules/xarray-einstats/default.nix b/pkgs/development/python-modules/xarray-einstats/default.nix
index ae8bd8f8c513..905d9e5799ed 100644
--- a/pkgs/development/python-modules/xarray-einstats/default.nix
+++ b/pkgs/development/python-modules/xarray-einstats/default.nix
@@ -39,7 +39,7 @@ buildPythonPackage rec {
     numba = [ numba ];
   };
 
-  nativeCheckInputs = [ pytestCheckHook ] ++ lib.flatten (builtins.attrValues optional-dependencies);
+  nativeCheckInputs = [ pytestCheckHook ] ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [ "xarray_einstats" ];
 
diff --git a/pkgs/development/python-modules/zeep/default.nix b/pkgs/development/python-modules/zeep/default.nix
index fe144dddf8a2..c59026888863 100644
--- a/pkgs/development/python-modules/zeep/default.nix
+++ b/pkgs/development/python-modules/zeep/default.nix
@@ -76,7 +76,7 @@ buildPythonPackage rec {
     pytestCheckHook
     requests-mock
   ]
-  ++ lib.flatten (builtins.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   disabledTests = [
     # Failed: External connections not allowed during tests.
diff --git a/pkgs/development/python-modules/zope-security/default.nix b/pkgs/development/python-modules/zope-security/default.nix
index a102151ee2e5..515709589bc2 100644
--- a/pkgs/development/python-modules/zope-security/default.nix
+++ b/pkgs/development/python-modules/zope-security/default.nix
@@ -59,7 +59,7 @@ buildPythonPackage rec {
     zope-exceptions
     zope-testing
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   # Import process is too complex and some tests fail
   preCheck = ''
diff --git a/pkgs/tools/security/cve-bin-tool/default.nix b/pkgs/tools/security/cve-bin-tool/default.nix
index 1c2913913e4b..c0286ed3ec2a 100644
--- a/pkgs/tools/security/cve-bin-tool/default.nix
+++ b/pkgs/tools/security/cve-bin-tool/default.nix
@@ -92,7 +92,7 @@ buildPythonApplication rec {
   nativeCheckInputs = [
     versionCheckHook
   ]
-  ++ lib.flatten (lib.attrValues optional-dependencies);
+  ++ lib.concatAttrValues optional-dependencies;
 
   pythonImportsCheck = [
     "cve_bin_tool"
diff --git a/pkgs/top-level/all-packages.nix b/pkgs/top-level/all-packages.nix
index 797c1f089bbd..9ed7f4a702ce 100644
--- a/pkgs/top-level/all-packages.nix
+++ b/pkgs/top-level/all-packages.nix
@@ -3465,7 +3465,7 @@ with pkgs;
     toPythonApplication (
       nvchecker.overridePythonAttrs (oldAttrs: {
         propagatedBuildInputs =
-          oldAttrs.dependencies ++ lib.flatten (builtins.attrValues oldAttrs.optional-dependencies);
+          oldAttrs.dependencies ++ lib.concatAttrValues oldAttrs.optional-dependencies;
       })
     );