diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 11667d614..ac831e7f3 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -27,15 +27,15 @@ jobs:
       contents: read
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v6
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6
         with:
           persist-credentials: false
-      - uses: astral-sh/setup-uv@681c641aba71e4a1c380be3ab5e12ad51f415867 # v7.1.6
+      - uses: astral-sh/setup-uv@08807647e7069bb48b6ef5acd8ec9567f424441b # v8.1.0
         with:
           cache-dependency-glob: ".github/workflows/*.yml"
           cache-suffix: pre-commit-uv
       - run: uv tool install pre-commit --with pre-commit-uv --force-reinstall
-      - uses: actions/cache@v5
+      - uses: actions/cache@27d5ce7f107fe9357f9df03efb73ab90386fccae # v5
         with:
           path: ~/.cache/pre-commit
           key: pre-commit-uv-v1-${{ hashFiles('.pre-commit-config.yaml') }}
@@ -67,15 +67,15 @@ jobs:
       BABEL_CLDR_QUIET: "1"
       PIP_DISABLE_PIP_VERSION_CHECK: "1"
     steps:
-    - uses: actions/checkout@v6
+    - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6
       with:
         persist-credentials: false
-    - uses: actions/cache@v5
+    - uses: actions/cache@27d5ce7f107fe9357f9df03efb73ab90386fccae # v5
       with:
         path: cldr
         key: cldr-${{ hashFiles('scripts/*cldr*') }}
     - name: Set up Python ${{ matrix.python-version }}
-      uses: actions/setup-python@v6
+      uses: actions/setup-python@a309ff8b426b58ec0e2a45f0f869d46889d02405 # v6
       with:
         python-version: ${{ matrix.python-version }}
         allow-prereleases: true
@@ -90,7 +90,7 @@ jobs:
       env:
         COVERAGE_XML_PATH: ${{ runner.temp }}
         BABEL_TOX_EXTRA_DEPS: pytest-github-actions-annotate-failures
-    - uses: codecov/codecov-action@671740ac38dd9b0130fbe1cec585b89eea48d3de # v5.5.2
+    - uses: codecov/codecov-action@57e3a136b779b570ffcdbf80b3bdc90e7fab3de2 # v6.0.0
       with:
         directory: ${{ runner.temp }}
         flags: ${{ matrix.os }}-${{ matrix.python-version }}
@@ -103,10 +103,10 @@ jobs:
     runs-on: ubuntu-24.04
     needs: lint
     steps:
-      - uses: actions/checkout@v6
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6
         with:
           persist-credentials: false
-      - uses: actions/setup-python@v6
+      - uses: actions/setup-python@a309ff8b426b58ec0e2a45f0f869d46889d02405 # v6
         with:
           python-version: "3.14"
           cache: "pip"
@@ -114,7 +114,7 @@ jobs:
       - run: pip install build -e .
       - run: make import-cldr
       - run: python -m build
-      - uses: actions/upload-artifact@v6
+      - uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7
         with:
           name: dist
           path: dist
@@ -130,12 +130,12 @@ jobs:
     permissions:
       id-token: write # Required for Trusted Publishing action
     steps:
-      - uses: actions/download-artifact@v7
+      - uses: actions/download-artifact@3e5f45b2cfb9172054b4087a40e8e0b5a5461e7c # v8
         with:
           name: dist
           path: dist/
       - name: Publish package distributions to PyPI
-        uses: pypa/gh-action-pypi-publish@ed0c53931b1dc9bd32cbe73a98c7f6766f8a527e # v1.13.0
+        uses: pypa/gh-action-pypi-publish@cef221092ed1bacb1cc03d23a2d87d1d172e277b # v1.14.0
         with:
           verbose: true
           print-hash: true
diff --git a/.github/workflows/security.yml b/.github/workflows/security.yml
index e4f467e38..83ae82929 100644
--- a/.github/workflows/security.yml
+++ b/.github/workflows/security.yml
@@ -22,8 +22,8 @@ jobs:
       security-events: write # via Zizmor example
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v6
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6
         with:
           persist-credentials: false
       - name: Run zizmor
-        uses: zizmorcore/zizmor-action@e639db99335bc9038abc0e066dfcd72e23d26fb4 # v0.3.0
+        uses: zizmorcore/zizmor-action@b1d7e1fb5de872772f31590499237e7cce841e8e # v0.5.3
diff --git a/Makefile b/Makefile
index 05f4d8434..fba85b899 100644
--- a/Makefile
+++ b/Makefile
@@ -20,4 +20,7 @@ develop:
 tox-test:
 	tox
 
-.PHONY: test develop tox-test clean-pyc clean-cldr import-cldr clean standalone-test
+update-gha:
+	uvx gha-tools@latest autoupdate --pin all -s specific --first-party-version-strategy=major --write .github/workflows/
+
+.PHONY: test develop tox-test clean-pyc clean-cldr import-cldr clean update-gha
diff --git a/babel/localedata.py b/babel/localedata.py
index 2b225a142..4648e6626 100644
--- a/babel/localedata.py
+++ b/babel/localedata.py
@@ -60,6 +60,7 @@ def resolve_locale_filename(name: os.PathLike[str] | str) -> str:
     return os.path.join(_dirname, f"{name}.dat")
 
 
+@lru_cache(maxsize=None)
 def exists(name: str) -> bool:
     """Check whether locale data is available for the given locale.
 
@@ -72,7 +73,7 @@ def exists(name: str) -> bool:
     if name in _cache:
         return True
     file_found = os.path.exists(resolve_locale_filename(name))
-    return True if file_found else bool(normalize_locale(name))
+    return file_found or bool(normalize_locale(name))
 
 
 @lru_cache(maxsize=None)
diff --git a/babel/units.py b/babel/units.py
index 88ebb909c..2c3462422 100644
--- a/babel/units.py
+++ b/babel/units.py
@@ -121,7 +121,7 @@ def format_unit(
 
     .. versionadded:: 2.2.0
 
-    :param value: the value to format. If this is a string, no number formatting will be attempted.
+    :param value: the value to format. If this is a string, no number formatting will be attempted and the number is assumed to be singular for the purposes of unit formatting.
     :param measurement_unit: the code of a measurement unit.
                              Known units can be found in the CLDR Unit Validity XML file:
                              https://unicode.org/repos/cldr/tags/latest/common/validity/unit.xml
@@ -137,7 +137,6 @@ def format_unit(
     q_unit = _find_unit_pattern(measurement_unit, locale=locale)
     if not q_unit:
         raise UnknownUnitError(unit=measurement_unit, locale=locale)
-    unit_patterns = locale._data["unit_patterns"][q_unit].get(length, {})
 
     if isinstance(value, str):  # Assume the value is a preformatted singular.
         formatted_value = value
@@ -151,8 +150,21 @@ def format_unit(
         )
         plural_form = locale.plural_form(value)
 
-    if plural_form in unit_patterns:
-        return unit_patterns[plural_form].format(formatted_value)
+    unit_patterns = locale._data["unit_patterns"][q_unit]
+
+    # We do not support `<alias>` tags at all while ingesting CLDR data,
+    # so these aliases specified in `root.xml` are hard-coded here:
+    # <unitLength type="long"><alias source="locale" path="../unitLength[@type='short']"/></unitLength>
+    # <unitLength type="narrow"><alias source="locale" path="../unitLength[@type='short']"/></unitLength>
+    lengths_to_check = [length, "short"] if length in ("long", "narrow") else [length]
+
+    for real_length in lengths_to_check:
+        length_patterns = unit_patterns.get(real_length, {})
+        # Fall back from the correct plural form to "other"
+        # (this is specified in LDML "Lateral Inheritance")
+        pat = length_patterns.get(plural_form) or length_patterns.get("other")
+        if pat:
+            return pat.format(formatted_value)
 
     # Fall back to a somewhat bad representation.
     # nb: This is marked as no-cover, as the current CLDR seemingly has no way for this to happen.
diff --git a/docs/api/dates.rst b/docs/api/dates.rst
index cbdac593b..9f0c80b57 100644
--- a/docs/api/dates.rst
+++ b/docs/api/dates.rst
@@ -40,8 +40,6 @@ Timezone Functionality
 
     A timezone object for the computer's local timezone.
 
-.. autoclass:: TimezoneTransition
-
 Data Access
 -----------
 
@@ -69,3 +67,9 @@ Basic Parsing
 .. autofunction:: parse_time
 
 .. autofunction:: parse_pattern
+
+Exceptions
+----------
+
+.. autoexception:: ParseError
+    :members:
diff --git a/docs/api/numbers.rst b/docs/api/numbers.rst
index d3ab8b116..c43bd56d2 100644
--- a/docs/api/numbers.rst
+++ b/docs/api/numbers.rst
@@ -36,19 +36,47 @@ Exceptions
 .. autoexception:: NumberFormatError
     :members:
 
+.. autoexception:: UnknownCurrencyError
+    :members:
+
+.. autoexception:: UnknownCurrencyFormatError
+    :members:
+
+.. autoexception:: UnsupportedNumberingSystemError
+    :members:
+
 Data Access
 -----------
 
+.. autofunction:: get_decimal_symbol
+
+.. autofunction:: get_exponential_symbol
+
+.. autofunction:: get_group_symbol
+
+.. autofunction:: get_infinity_symbol
+
+.. autofunction:: get_minus_sign_symbol
+
+.. autofunction:: get_plus_sign_symbol
+
+Currency Utilities
+------------------
+
 .. autofunction:: get_currency_name
 
+.. autofunction:: get_currency_precision
+
 .. autofunction:: get_currency_symbol
 
 .. autofunction:: get_currency_unit_pattern
 
-.. autofunction:: get_decimal_symbol
+.. autofunction:: get_territory_currencies
 
-.. autofunction:: get_plus_sign_symbol
+.. autofunction:: is_currency
 
-.. autofunction:: get_minus_sign_symbol
+.. autofunction:: list_currencies
 
-.. autofunction:: get_territory_currencies
+.. autofunction:: normalize_currency
+
+.. autofunction:: validate_currency
diff --git a/docs/api/plural.rst b/docs/api/plural.rst
index d6934b576..c40f29f04 100644
--- a/docs/api/plural.rst
+++ b/docs/api/plural.rst
@@ -21,3 +21,9 @@ Conversion Functionality
 .. autofunction:: to_python
 
 .. autofunction:: to_gettext
+
+Exceptions
+----------
+
+.. autoexception:: RuleError
+    :members:
diff --git a/docs/api/units.rst b/docs/api/units.rst
index 2b99be547..db94b7055 100644
--- a/docs/api/units.rst
+++ b/docs/api/units.rst
@@ -11,3 +11,9 @@ locales.
 .. autofunction:: format_compound_unit
 
 .. autofunction:: get_unit_name
+
+Exceptions
+----------
+
+.. autoexception:: UnknownUnitError
+    :members:
diff --git a/docs/conf.py b/docs/conf.py
index b22b78c4f..eb8175796 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -44,16 +44,16 @@
 
 # General information about the project.
 project = 'Babel'
-copyright = '2025, The Babel Team'
+copyright = '2026, The Babel Team'
 
 # The version info for the project you're documenting, acts as replacement for
 # |version| and |release|, also used in various other places throughout the
 # built documents.
 #
 # The short X.Y version.
-version = '2.17'
+version = '2.18'
 # The full version, including alpha/beta/rc tags.
-release = '2.17.0'
+release = '2.18.0'
 
 # The language for content autogenerated by Sphinx. Refer to documentation
 # for a list of supported languages.
diff --git a/docs/requirements.txt b/docs/requirements.txt
index c133306c7..4864c69dd 100644
--- a/docs/requirements.txt
+++ b/docs/requirements.txt
@@ -1 +1 @@
-Sphinx~=5.3.0
+Sphinx~=9.1.0
diff --git a/tests/test_localedata.py b/tests/test_localedata.py
index 03cbed1dc..42810b992 100644
--- a/tests/test_localedata.py
+++ b/tests/test_localedata.py
@@ -109,10 +109,10 @@ def test_locale_argument_acceptance():
     assert normalized_locale is None
     assert not localedata.exists(None)
 
-    # Testing list input.
+    # Testing tuple input.
     normalized_locale = localedata.normalize_locale(['en_us', None])
     assert normalized_locale is None
-    assert not localedata.exists(['en_us', None])
+    assert not localedata.exists(('en_us', None))
 
 
 def test_locale_identifiers_cache(monkeypatch):
diff --git a/tests/test_units.py b/tests/test_units.py
index 7c6ad6b4d..27b7535fe 100644
--- a/tests/test_units.py
+++ b/tests/test_units.py
@@ -17,3 +17,15 @@
 ])
 def test_new_cldr46_units(unit, count, expected):
     assert format_unit(count, unit, locale='cs_CZ') == expected
+
+
+@pytest.mark.parametrize('count, unit, locale, length, expected', [
+    (1, 'duration-month', 'et', 'long', '1 kuu'),
+    (1, 'duration-minute', 'et', 'narrow', '1 min'),
+    (2, 'duration-minute', 'et', 'narrow', '2 min'),
+    (2, 'digital-byte', 'et', 'long', '2 baiti'),
+    (1, 'duration-day', 'it', 'long', '1 giorno'),
+    (1, 'duration-day', 'it', 'short', '1 giorno'),
+])
+def test_issue_1217(count, unit, locale, length, expected):
+    assert format_unit(count, unit, length, locale=locale) == expected
diff --git a/tox.ini b/tox.ini
index a48dca512..d5f3e326b 100644
--- a/tox.ini
+++ b/tox.ini
@@ -10,7 +10,11 @@ envlist =
 [testenv]
 extras =
     dev
-deps = {env:BABEL_TOX_EXTRA_DEPS:}
+deps =
+    # On Python 3.9, we need a version of Setuptools that still has pkg_resources
+    # to be able to run the Jinja extractor tests.
+    py39: setuptools<82
+    {env:BABEL_TOX_EXTRA_DEPS:}
 allowlist_externals = make
 commands = make clean-cldr test
 setenv =