diff --git a/.github/workflows/auto-dependabot.yaml b/.github/workflows/auto-dependabot.yaml
index 58c5355..9b1a5ef 100644
--- a/.github/workflows/auto-dependabot.yaml
+++ b/.github/workflows/auto-dependabot.yaml
@@ -28,7 +28,7 @@ jobs:
     steps:
       - name: Generate GitHub App token
         id: app-token
-        uses: actions/create-github-app-token@f8d387b68d61c58ab83c6c016672934102569859 # v3.0.0
+        uses: actions/create-github-app-token@29824e69f54612133e76f7eaac726eef6c875baf # v2.2.1
         with:
           app-id: ${{ secrets.FREQUENZ_AUTO_DEPENDABOT_APP_ID }}
           private-key: ${{ secrets.FREQUENZ_AUTO_DEPENDABOT_APP_PRIVATE_KEY }}
diff --git a/.github/workflows/black-migration.yaml b/.github/workflows/black-migration.yaml
index d22b182..1969c46 100644
--- a/.github/workflows/black-migration.yaml
+++ b/.github/workflows/black-migration.yaml
@@ -66,7 +66,7 @@ jobs:
           # Read/update pull request metadata and labels.
           permission-pull-requests: write
       - name: Migrate
-        uses: llucax/gh-action-dependabot-migrate@90f41ef501378754ffbcd3a75bc907ac9fe1b31e # internal-script
+        uses: frequenz-floss/gh-action-dependabot-migrate@b389f72f9282346920150a67495efbae450ac07b  # v1.1.0
         with:
           migration-script: |
             import os
diff --git a/.github/workflows/ci-pr.yaml b/.github/workflows/ci-pr.yaml
index ac6905d..015d585 100644
--- a/.github/workflows/ci-pr.yaml
+++ b/.github/workflows/ci-pr.yaml
@@ -3,6 +3,10 @@ name: Test PR
 on:
   pull_request:
 
+permissions:
+  # Read repository contents for checkout and dependency resolution only.
+  contents: read
+
 env:
   # Please make sure this version is included in the `matrix`, as the
   # `matrix` section can't use `env`, so it must be entered manually
@@ -17,7 +21,7 @@ jobs:
 
     steps:
       - name: Run nox
-        uses: frequenz-floss/gh-action-nox@v1.1.1
+        uses: frequenz-floss/gh-action-nox@e1351cf45e05e85afc1c79ab883e06322892d34c # v1.1.0
         with:
           python-version: "3.11"
           nox-session: ci_checks_max
@@ -27,15 +31,15 @@ jobs:
     runs-on: ubuntu-24.04
     steps:
       - name: Setup Git
-        uses: frequenz-floss/gh-action-setup-git@v1.0.0
+        uses: frequenz-floss/gh-action-setup-git@16952aac3ccc01d27412fe0dea3ea946530dcace # v1.0.0
 
       - name: Fetch sources
-        uses: actions/checkout@v6
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
         with:
           submodules: true
 
       - name: Setup Python
-        uses: frequenz-floss/gh-action-setup-python-with-deps@v1.0.4
+        uses: frequenz-floss/gh-action-setup-python-with-deps@0d0d77eac3b54799f31f25a1060ef2c6ebdf9299 # v1.0.2
         with:
           python-version: ${{ env.DEFAULT_PYTHON_VERSION }}
           dependencies: .[dev-mkdocs]
@@ -44,11 +48,14 @@ jobs:
         env:
           MIKE_VERSION: gh-${{ github.job }}
         run: |
-          mike deploy $MIKE_VERSION
-          mike set-default $MIKE_VERSION
+          # mike is installed as a console script, not a runnable module.
+          # Run the installed script under isolated mode to avoid importing from
+          # the workspace when building docs from checked-out code.
+          python -I "$(command -v mike)" deploy "$MIKE_VERSION"
+          python -I "$(command -v mike)" set-default "$MIKE_VERSION"
 
       - name: Upload site
-        uses: actions/upload-artifact@v7
+        uses: actions/upload-artifact@bbbca2ddaa5d8feaa63e36b76fdaad77386f024f # v7.0.0
         with:
           name: docs-site
           path: site/
diff --git a/.github/workflows/ci.yaml b/.github/workflows/ci.yaml
index 95f10f8..c3b4cfb 100644
--- a/.github/workflows/ci.yaml
+++ b/.github/workflows/ci.yaml
@@ -15,6 +15,10 @@ on:
       - 'dependabot/**'
   workflow_dispatch:
 
+permissions:
+  # Read repository contents for checkout and dependency resolution only.
+  contents: read
+
 env:
   # Please make sure this version is included in the `matrix`, as the
   # `matrix` section can't use `env`, so it must be entered manually
@@ -28,11 +32,9 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        arch:
-          - amd64
-          - arm
-        os:
+        platform:
           - ubuntu-24.04
+          - ubuntu-24.04-arm
         python:
           - "3.11"
           - "3.12"
@@ -41,11 +43,11 @@ jobs:
           # that uses the same venv to run multiple linting sessions
           - "ci_checks_max"
           - "pytest_min"
-    runs-on: ${{ matrix.os }}${{ matrix.arch != 'amd64' && format('-{0}', matrix.arch) || '' }}
+    runs-on: ${{ matrix.platform }}
 
     steps:
       - name: Run nox
-        uses: frequenz-floss/gh-action-nox@v1.1.1
+        uses: frequenz-floss/gh-action-nox@e1351cf45e05e85afc1c79ab883e06322892d34c # v1.1.0
         with:
           python-version: ${{ matrix.python }}
           nox-session: ${{ matrix.nox-session }}
@@ -60,7 +62,9 @@ jobs:
     needs: ["nox"]
     # We skip this job only if nox was also skipped
     if: always() && needs.nox.result != 'skipped'
-    runs-on: ubuntu-24.04
+    runs-on: ubuntu-slim
+    # Drop token permissions: this job only checks matrix status from `needs`.
+    permissions: {}
     env:
       DEPS_RESULT: ${{ needs.nox.result }}
     steps:
@@ -76,24 +80,24 @@ jobs:
 
     steps:
       - name: Setup Git
-        uses: frequenz-floss/gh-action-setup-git@v1.0.0
+        uses: frequenz-floss/gh-action-setup-git@16952aac3ccc01d27412fe0dea3ea946530dcace # v1.0.0
 
       - name: Fetch sources
-        uses: actions/checkout@v6
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
         with:
           submodules: true
 
       - name: Setup Python
-        uses: frequenz-floss/gh-action-setup-python-with-deps@v1.0.4
+        uses: frequenz-floss/gh-action-setup-python-with-deps@0d0d77eac3b54799f31f25a1060ef2c6ebdf9299 # v1.0.2
         with:
           python-version: ${{ env.DEFAULT_PYTHON_VERSION }}
           dependencies: build
 
       - name: Build the source and binary distribution
-        run: python -m build
+        run: python -Im build
 
       - name: Upload distribution files
-        uses: actions/upload-artifact@v7
+        uses: actions/upload-artifact@bbbca2ddaa5d8feaa63e36b76fdaad77386f024f # v7.0.0
         with:
           name: dist-packages
           path: dist/
@@ -105,25 +109,23 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        arch:
-          - amd64
-          - arm
-        os:
+        platform:
           - ubuntu-24.04
+          - ubuntu-24.04-arm
         python:
           - "3.11"
           - "3.12"
-    runs-on: ${{ matrix.os }}${{ matrix.arch != 'amd64' && format('-{0}', matrix.arch) || '' }}
+    runs-on: ${{ matrix.platform }}
 
     steps:
       - name: Setup Git
-        uses: frequenz-floss/gh-action-setup-git@v1.0.0
+        uses: frequenz-floss/gh-action-setup-git@16952aac3ccc01d27412fe0dea3ea946530dcace # v1.0.0
 
       - name: Print environment (debug)
         run: env
 
       - name: Download package
-        uses: actions/download-artifact@v8
+        uses: actions/download-artifact@3e5f45b2cfb9172054b4087a40e8e0b5a5461e7c # v8.0.1
         with:
           name: dist-packages
           path: dist
@@ -143,13 +145,13 @@ jobs:
             > pyproject.toml
 
       - name: Setup Python
-        uses: frequenz-floss/gh-action-setup-python-with-deps@v1.0.4
+        uses: frequenz-floss/gh-action-setup-python-with-deps@0d0d77eac3b54799f31f25a1060ef2c6ebdf9299 # v1.0.2
         with:
           python-version: ${{ matrix.python }}
           dependencies: dist/*.whl
 
       - name: Print installed packages (debug)
-        run: python -m pip freeze
+        run: python -Im pip freeze
 
   # This job runs if all the `test-installation` matrix jobs ran and succeeded.
   # It is only used to have a single job that we can require in branch
@@ -161,7 +163,9 @@ jobs:
     needs: ["test-installation"]
     # We skip this job only if test-installation was also skipped
     if: always() && needs.test-installation.result != 'skipped'
-    runs-on: ubuntu-24.04
+    runs-on: ubuntu-slim
+    # Drop token permissions: this job only checks matrix status from `needs`.
+    permissions: {}
     env:
       DEPS_RESULT: ${{ needs.test-installation.result }}
     steps:
@@ -174,15 +178,15 @@ jobs:
     runs-on: ubuntu-24.04
     steps:
       - name: Setup Git
-        uses: frequenz-floss/gh-action-setup-git@v1.0.0
+        uses: frequenz-floss/gh-action-setup-git@16952aac3ccc01d27412fe0dea3ea946530dcace # v1.0.0
 
       - name: Fetch sources
-        uses: actions/checkout@v6
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
         with:
           submodules: true
 
       - name: Setup Python
-        uses: frequenz-floss/gh-action-setup-python-with-deps@v1.0.4
+        uses: frequenz-floss/gh-action-setup-python-with-deps@0d0d77eac3b54799f31f25a1060ef2c6ebdf9299 # v1.0.2
         with:
           python-version: ${{ env.DEFAULT_PYTHON_VERSION }}
           dependencies: .[dev-mkdocs]
@@ -191,11 +195,14 @@ jobs:
         env:
           MIKE_VERSION: gh-${{ github.job }}
         run: |
-          mike deploy $MIKE_VERSION
-          mike set-default $MIKE_VERSION
+          # mike is installed as a console script, not a runnable module.
+          # Run the installed script under isolated mode to avoid importing from
+          # the workspace when building docs from checked-out code.
+          python -I "$(command -v mike)" deploy "$MIKE_VERSION"
+          python -I "$(command -v mike)" set-default "$MIKE_VERSION"
 
       - name: Upload site
-        uses: actions/upload-artifact@v7
+        uses: actions/upload-artifact@bbbca2ddaa5d8feaa63e36b76fdaad77386f024f # v7.0.0
         with:
           name: docs-site
           path: site/
@@ -207,18 +214,19 @@ jobs:
     if: github.event_name == 'push'
     runs-on: ubuntu-24.04
     permissions:
+      # Push generated documentation updates to the `gh-pages` branch.
       contents: write
     steps:
       - name: Setup Git
-        uses: frequenz-floss/gh-action-setup-git@v1.0.0
+        uses: frequenz-floss/gh-action-setup-git@16952aac3ccc01d27412fe0dea3ea946530dcace # v1.0.0
 
       - name: Fetch sources
-        uses: actions/checkout@v6
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
         with:
           submodules: true
 
       - name: Setup Python
-        uses: frequenz-floss/gh-action-setup-python-with-deps@v1.0.4
+        uses: frequenz-floss/gh-action-setup-python-with-deps@0d0d77eac3b54799f31f25a1060ef2c6ebdf9299 # v1.0.2
         with:
           python-version: ${{ env.DEFAULT_PYTHON_VERSION }}
           dependencies: .[dev-mkdocs]
@@ -231,7 +239,7 @@ jobs:
           GIT_REF: ${{ github.ref }}
           GIT_SHA: ${{ github.sha }}
         run: |
-          python -m frequenz.repo.config.cli.version.mike.info
+          python -Im frequenz.repo.config.cli.version.mike.info
 
       - name: Fetch the gh-pages branch
         if: steps.mike-version.outputs.version
@@ -252,13 +260,23 @@ jobs:
           GIT_REF: ${{ github.ref }}
           GIT_SHA: ${{ github.sha }}
         run: |
-          mike deploy --update-aliases --title "$TITLE" "$VERSION" $ALIASES
+          # Collect aliases into an array to avoid accidental (or malicious)
+          # shell injection when passing them to mike.
+          aliases=()
+          if test -n "$ALIASES"; then
+            read -r -a aliases <<<"$ALIASES"
+          fi
+          # mike is installed as a console script, not a runnable module.
+          # Run the installed script under isolated mode to avoid importing from
+          # the workspace when building docs from checked-out code.
+          python -I "$(command -v mike)" \
+            deploy --update-aliases --title "$TITLE" "$VERSION" "${aliases[@]}"
 
       - name: Sort site versions
         if: steps.mike-version.outputs.version
         run: |
           git checkout gh-pages
-          python -m frequenz.repo.config.cli.version.mike.sort versions.json
+          python -Im frequenz.repo.config.cli.version.mike.sort versions.json
           git commit -a -m "Sort versions.json"
 
       - name: Publish site
@@ -272,14 +290,12 @@ jobs:
     # Create a release only on tags creation
     if: github.event_name == 'push' && startsWith(github.ref, 'refs/tags/v')
     permissions:
-      # We need write permissions on contents to create GitHub releases and on
-      # discussions to create the release announcement in the discussion forums
+      # Create GitHub releases and upload distribution artifacts.
       contents: write
-      discussions: write
-    runs-on: ubuntu-24.04
+    runs-on: ubuntu-slim
     steps:
       - name: Download distribution files
-        uses: actions/download-artifact@v8
+        uses: actions/download-artifact@3e5f45b2cfb9172054b4087a40e8e0b5a5461e7c # v8.0.1
         with:
           name: dist-packages
           path: dist
@@ -301,14 +317,14 @@ jobs:
       - name: Create GitHub release
         run: |
           set -ux
-          extra_opts=
-          if echo "$REF_NAME" | grep -- -; then extra_opts=" --prerelease"; fi
+          extra_opts=()
+          if echo "$REF_NAME" | grep -- -; then extra_opts+=(--prerelease); fi
           gh release create \
             -R "$REPOSITORY" \
             --notes-file RELEASE_NOTES.md \
             --generate-notes \
-            $extra_opts \
-            $REF_NAME \
+            "${extra_opts[@]}" \
+            "$REF_NAME" \
             dist/*
         env:
           REF_NAME: ${{ github.ref_name }}
@@ -325,10 +341,10 @@ jobs:
       id-token: write
     steps:
       - name: Download distribution files
-        uses: actions/download-artifact@v8
+        uses: actions/download-artifact@3e5f45b2cfb9172054b4087a40e8e0b5a5461e7c # v8.0.1
         with:
           name: dist-packages
           path: dist
 
       - name: Publish the Python distribution to PyPI
-        uses: pypa/gh-action-pypi-publish@release/v1
+        uses: pypa/gh-action-pypi-publish@ed0c53931b1dc9bd32cbe73a98c7f6766f8a527e # v1.13.0
diff --git a/.github/workflows/dco-merge-queue.yml b/.github/workflows/dco-merge-queue.yml
index fb1cd90..7a4260d 100644
--- a/.github/workflows/dco-merge-queue.yml
+++ b/.github/workflows/dco-merge-queue.yml
@@ -3,9 +3,12 @@ name: DCO
 on:
   merge_group:
 
+# Drop all token permissions: this workflow only runs a local echo command.
+permissions: {}
+
 jobs:
   DCO:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-slim
     if: ${{ github.actor != 'dependabot[bot]' }}
     steps:
       - run: echo "This DCO job runs on merge_queue event and doesn't check PR contents"
diff --git a/.github/workflows/labeler.yml b/.github/workflows/labeler.yml
index 8d02c13..393ddfc 100644
--- a/.github/workflows/labeler.yml
+++ b/.github/workflows/labeler.yml
@@ -5,9 +5,11 @@ on: [pull_request_target]
 jobs:
   Label:
     permissions:
+      # Read the labeler configuration from the repository.
       contents: read
+      # Add labels to pull requests.
       pull-requests: write
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-slim
     steps:
       - name: Labeler
         # XXX: !!! SECURITY WARNING !!!
diff --git a/.github/workflows/release-notes-check.yml b/.github/workflows/release-notes-check.yml
index 41212e8..74ca95f 100644
--- a/.github/workflows/release-notes-check.yml
+++ b/.github/workflows/release-notes-check.yml
@@ -16,7 +16,10 @@ on:
 jobs:
   check-release-notes:
     name: Check release notes are updated
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-slim
+    permissions:
+      # Read pull request metadata to evaluate labels and changed files.
+      pull-requests: read
     steps:
       - name: Check for a release notes update
         if: github.event_name == 'pull_request'
diff --git a/.github/workflows/repo-config-migration.yaml b/.github/workflows/repo-config-migration.yaml
index 09602d4..a3addbd 100644
--- a/.github/workflows/repo-config-migration.yaml
+++ b/.github/workflows/repo-config-migration.yaml
@@ -24,8 +24,11 @@ on:
     types: [opened, synchronize, reopened, labeled, unlabeled]
 
 permissions:
+  # Commit migration changes back to the PR branch.
   contents: write
+  # Create and normalize migration state labels.
   issues: write
+  # Read/update pull request metadata and comments.
   pull-requests: write
 
 jobs:
@@ -42,12 +45,20 @@ jobs:
     steps:
       - name: Generate token
         id: create-app-token
-        uses: actions/create-github-app-token@f8d387b68d61c58ab83c6c016672934102569859 # v3.0.0
+        uses: actions/create-github-app-token@29824e69f54612133e76f7eaac726eef6c875baf # v2.2.1
         with:
           app-id: ${{ secrets.FREQUENZ_AUTO_DEPENDABOT_APP_ID }}
           private-key: ${{ secrets.FREQUENZ_AUTO_DEPENDABOT_APP_PRIVATE_KEY }}
+          # Push migration commits to the PR branch.
+          permission-contents: write
+          # Manage labels when auto-merging patch-only updates.
+          permission-issues: write
+          # Approve pull requests and enable auto-merge.
+          permission-pull-requests: write
+          # Allow pushes when migration changes workflow files.
+          permission-workflows: write
       - name: Migrate
-        uses: frequenz-floss/gh-action-dependabot-migrate@b389f72f9282346920150a67495efbae450ac07b # v1.1.0
+        uses: frequenz-floss/gh-action-dependabot-migrate@07dc7e74726498c50726a80cc2167a04d896508f # v1.0.0
         with:
           script-url-template: >-
             https://raw.githubusercontent.com/frequenz-floss/frequenz-repo-config-python/{version}/cookiecutter/migrate.py
diff --git a/pyproject.toml b/pyproject.toml
index cbcbb63..e5e1b71 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -5,7 +5,7 @@
 requires = [
   "setuptools == 82.0.1",
   "setuptools_scm[toml] == 10.0.5",
-  "frequenz-repo-config[lib] == 0.14.0",
+  "frequenz-repo-config[lib] == 0.17.0",
 ]
 build-backend = "setuptools.build_meta"
 
@@ -13,12 +13,12 @@ build-backend = "setuptools.build_meta"
 name = "frequenz-client-common"
 description = "Common code and utilities for Frequenz API clients"
 readme = "README.md"
-license = { text = "MIT" }
+license = "MIT"
+license-files = ["LICENSE"]
 keywords = ["frequenz", "python", "lib", "library", "client-common"]
 classifiers = [
   "Development Status :: 3 - Alpha",
   "Intended Audience :: Developers",
-  "License :: OSI Approved :: MIT License",
   "Programming Language :: Python :: 3",
   "Programming Language :: Python :: 3 :: Only",
   "Topic :: Software Development :: Libraries",
@@ -40,6 +40,7 @@ email = "floss@frequenz.com"
 [project.optional-dependencies]
 dev-flake8 = [
   "flake8 == 7.3.0",
+  "flake8-datetimez == 20.10.0",
   "flake8-docstrings == 1.7.0",
   "flake8-pyproject == 1.2.4", # For reading the flake8 config from pyproject.toml
   "pydoclint == 0.8.3",
@@ -56,7 +57,7 @@ dev-mkdocs = [
   "mkdocs-material == 9.7.6",
   "mkdocstrings[python] == 1.0.3",
   "mkdocstrings-python == 2.0.3",
-  "frequenz-repo-config[lib] == 0.14.0",
+  "frequenz-repo-config[lib] == 0.17.0",
 ]
 dev-mypy = [
   "mypy == 1.20.0",
@@ -65,7 +66,7 @@ dev-mypy = [
   # For checking the noxfile, docs/ script, and tests
   "frequenz-client-common[dev-mkdocs,dev-noxfile,dev-pytest]",
 ]
-dev-noxfile = ["nox == 2026.2.9", "frequenz-repo-config[lib] == 0.14.0"]
+dev-noxfile = ["nox == 2026.2.9", "frequenz-repo-config[lib] == 0.17.0"]
 dev-pylint = [
   "pylint == 4.0.5",
   # For checking the noxfile, docs/ script, and tests
@@ -73,7 +74,7 @@ dev-pylint = [
 ]
 dev-pytest = [
   "pytest == 9.0.2",
-  "frequenz-repo-config[extra-lint-examples] == 0.14.0",
+  "frequenz-repo-config[extra-lint-examples] == 0.17.0",
   "hypothesis == 6.151.10",
   "pytest-mock == 3.15.1",
   "pytest-asyncio == 1.3.0",
diff --git a/tests/proto/test_datetime.py b/tests/proto/test_datetime.py
index 0025d7f..82c6eb4 100644
--- a/tests/proto/test_datetime.py
+++ b/tests/proto/test_datetime.py
@@ -15,9 +15,10 @@
 from frequenz.client.common.proto import datetime_from_proto, datetime_to_proto
 
 # Strategy for generating datetime objects
+# It requires naive datetime objects because it creates the timezone via a strategy
 datetime_strategy = st.datetimes(
-    min_value=datetime(1970, 1, 1),
-    max_value=datetime(9999, 12, 31),
+    min_value=datetime(1970, 1, 1),  # noqa: DTZ001
+    max_value=datetime(9999, 12, 31),  # noqa: DTZ001
     timezones=st.just(timezone.utc),
 )