diff --git a/.github/workflows/pytest-snapshots.yaml b/.github/workflows/pytest-snapshots.yaml
index 1348cd4163..85240bad79 100644
--- a/.github/workflows/pytest-snapshots.yaml
+++ b/.github/workflows/pytest-snapshots.yaml
@@ -13,14 +13,16 @@ concurrency:
   group: ${{ github.workflow }}-${{ github.head_ref || github.run_id }}
   cancel-in-progress: true
 
+env:
+  version:
+    gams: "43.4.1"
+    python: "3.12"
+    upstream: main
+
 jobs:
   snapshots:
     runs-on: ubuntu-latest
     name: Test snapshots ubuntu-latest
-    env:
-      upstream-version: main
-      python-version: "3.12"
-      extra-deps: 'dask[dataframe]'
 
     steps:
     - name: Cache test data
@@ -33,17 +35,16 @@ jobs:
       uses: actions/checkout@v4
       with:
         lfs: true
-        fetch-depth: ${{ env.depth }}
 
     - uses: actions/setup-python@v5
       with:
-        python-version: ${{ env.python-version }}
+        python-version: ${{ env.version.python }}
         cache: pip
         cache-dependency-path: "**/pyproject.toml"
 
     - uses: iiasa/actions/setup-gams@main
       with:
-        version: 29.1.0
+        version: ${{ env.version.gams }}
         license: ${{ secrets.GAMS_LICENSE }}
 
     - uses: ts-graphviz/setup-graphviz@v2
@@ -52,7 +53,7 @@ jobs:
 
     - name: Install packages and dependencies
       # By default, install:
-      # - ixmp, message_ix: from GitHub branches/tags per env.upstream-version (above)
+      # - ixmp, message_ix: from GitHub branches/tags per env.version.upstream (above)
       # - other dependencies including genno: from PyPI.
       #
       # To test against unreleased code (on `main`, or other branches
@@ -60,11 +61,11 @@ jobs:
       # as needed. DO NOT merge such changes to `main`.
       run: |
         # pip install --upgrade "genno @ git+https://github.com/khaeru/genno.git@main"
-        pip install --upgrade "ixmp @ git+https://github.com/iiasa/ixmp.git@${{ env.upstream-version }}"
-        # pip install --upgrade "message-ix @ git+https://github.com/iiasa/message_ix.git@${{ env.upstream-version }}"
+        pip install --upgrade "ixmp @ git+https://github.com/iiasa/ixmp.git@${{ env.version.upstream }}"
+        # pip install --upgrade "message-ix @ git+https://github.com/iiasa/message_ix.git@${{ env.version.upstream }}"
         pip install --upgrade "message-ix @ git+https://github.com/iiasa/message_ix.git@issue/723"
 
-        pip install .[docs,tests] ${{ env.extra-deps }}
+        pip install .[docs,tests] dask[dataframe]
 
     - name: Configure local data path
       run: |
@@ -86,4 +87,4 @@ jobs:
     - name: Upload test coverage to Codecov.io
       uses: codecov/codecov-action@v5
       with:
-        token: ${{ secrets.CODECOV_TOKEN }} # required
\ No newline at end of file
+        token: ${{ secrets.CODECOV_TOKEN }} # required
diff --git a/.github/workflows/pytest.yaml b/.github/workflows/pytest.yaml
index 36ea581978..0d30b3a7dc 100644
--- a/.github/workflows/pytest.yaml
+++ b/.github/workflows/pytest.yaml
@@ -16,10 +16,10 @@ jobs:
   warm-lfs-cache:
     strategy:
       matrix:
-        os: [ macos-13, ubuntu-latest, windows-latest ]
+        os: [ macos-13, macos-latest, ubuntu-latest, windows-latest ]
     runs-on: ${{ matrix.os }}
     steps:
-    - uses: nschloe/action-cached-lfs-checkout@v1
+    - uses: francisbilham11/action-cached-lfs-checkout@v3
 
   pytest:
     needs: warm-lfs-cache
@@ -28,52 +28,40 @@ jobs:
       matrix:
         os:
         - macos-13
+        - macos-latest
         - ubuntu-latest
         - windows-latest
-        upstream:
+        version:
         # In each group:
         # - Versions of ixmp and message_ix to test.
         # - Latest supported Python version for those or other dependencies.
-        # - Extra dependencies, in particular fixed/maximum versions to resolve conficts.
-        #   - dask[dataframe] >= 2024.3.0 requires dask-expr and in turn pandas >= 2.0.
-        #     https://github.com/iiasa/message-ix-models/pull/156#issuecomment-2020152360
-        #   - genno: upstream versions < 3.8.0 import genno.computations, removed in 1.25.0.
-        #     https://github.com/iiasa/message-ix-models/pull/156
-        #   - pytest: upstream versions < 3.9.0 use a hook argument removed in pytest 8.1.0.
-        #     https://github.com/iiasa/message-ix-models/pull/155
-        #
-        # Minimum version given in pyproject.toml
-        - version: v3.4.0
-          python-version: "3.11"
-          extra-deps: '"dask < 2024.3.0" "genno < 1.25" "pandas < 2.0" "pytest == 8.0.0"' #
-          dask-dataframe: false
-        - version: v3.5.0
-          python-version: "3.11"
-          extra-deps: '"dask < 2024.3.0" "genno < 1.25" "pandas < 2.0" "pytest == 8.0.0"' #
-          dask-dataframe: false
-        - version: v3.6.0
-          python-version: "3.11"
-          extra-deps: '"dask < 2024.3.0" "genno < 1.25" "pandas < 2.0" "pytest == 8.0.0"' #
-          dask-dataframe: false
-        - version: v3.7.0
-          python-version: "3.11"
-          extra-deps: '                  "genno < 1.25"                "pytest == 8.0.0"' #
-          dask-dataframe: true
-        # Latest released version
-        - version: v3.8.0
-          python-version: "3.12"
-          extra-deps: '                                                "pytest == 8.0.0"' #
-          dask-dataframe: true
-        # Development version
-        - version: main
-          python-version: "3.12"
-          extra-deps: '' #
-          dask-dataframe: true
+        # Minimum version given in pyproject.toml + earlier version of Python
+        - { upstream: v3.4.0, python: "3.11" }  # 2022-01-27
+        - { upstream: v3.5.0, python: "3.11" }  # 2022-05-06
+        - { upstream: v3.6.0, python: "3.11" }  # 2022-08-18
+        - { upstream: v3.7.0, python: "3.11" }  # 2023-05-17
+        - { upstream: v3.8.0, python: "3.12" }  # 2024-01-12
+        # Latest released version + latest released Python
+        - { upstream: v3.9.0, python: "3.13" }  # 2024-06-04
+        # Development version + latest released Python
+        - { upstream: main,   python: "3.13" }
+
+        exclude:
+        # Specific version combinations that are invalid / not to be used
+        # These versions of ixmp are not able locate the arm64 GAMS API binaries
+        - { os: macos-latest, version: {upstream: v3.4.0 }}
+        - { os: macos-latest, version: {upstream: v3.5.0 }}
+        - { os: macos-latest, version: {upstream: v3.6.0 }}
+        - { os: macos-latest, version: {upstream: v3.7.0 }}
+        - { os: macos-latest, version: {upstream: v3.8.0 }}
+        - { os: macos-latest, version: {upstream: v3.9.0 }}
+        # Redundant with macos-latest
+        - { os: macos-13, version: {upstream: main }}
 
       fail-fast: false
 
     runs-on: ${{ matrix.os }}
-    name: ${{ matrix.os }}-py${{ matrix.upstream.python-version }}-upstream-${{ matrix.upstream.version }}
+    name: ${{ matrix.os }}-py${{ matrix.version.python }}-upstream-${{ matrix.version.upstream }}
 
     steps:
     - name: Cache test data
@@ -83,45 +71,59 @@ jobs:
         key: ${{ matrix.os }}
 
     - name: Check out message-ix-models
-      uses: nschloe/action-cached-lfs-checkout@v1
+      uses: francisbilham11/action-cached-lfs-checkout@v3
 
     - uses: actions/setup-python@v5
       with:
-        python-version: ${{ matrix.upstream.python-version }}
+        python-version: ${{ matrix.version.python }}
         cache: pip
         cache-dependency-path: "**/pyproject.toml"
 
     - uses: iiasa/actions/setup-gams@main
       with:
-        version: 29.1.0
+        version: 43.4.1
         license: ${{ secrets.GAMS_LICENSE }}
 
     - uses: ts-graphviz/setup-graphviz@v2
-      # TEMPORARY Work around ts-graphviz/setup-graphviz#630
-      if: ${{ ! startswith(matrix.os, 'macos-') }}
+      # Work around ts-graphviz/setup-graphviz#630
+      if: ${{ matrix.os != 'macos-13' }}
+
+    - name: Determine extra dependencies
+      id: extra-deps
+      run : |
+        from os import environ
+        from pathlib import Path
+
+        v, result = "${{ matrix.version.upstream }}".replace("main", "vmain"), []
+        for condition, dependency in (
+            (v <= "v3.6.0", "dask < 2024.3.0"),  # dask[dataframe] >= 2024.3.0 requires dask-expr and in turn pandas >= 2.0 (#156)
+            (v <= "v3.6.0", "pandas < 2.0"),
+            (v >= "v3.7.0", "dask[dataframe] < 2024.11.0"),  # dask >= 2024.11.0 changes handling of dict (will be addressed in #225)
+            (v <= "v3.7.0", "genno < 1.25"),  # Upstream versions < 3.8.0 import genno.computations, removed in 1.25.0 (#156)
+            (v < "v3.9.0", "pytest == 8.0.0"),  # Upstream versions < 3.9.0 use a hook argument removed in pytest 8.1.0 (#155)
+        ):
+            result.extend([f'"{dependency}"'] if condition else [])
+
+        Path(environ["GITHUB_OUTPUT"]).write_text(f"value={' '.join(result)}\n")
+      shell: python
 
     - name: Install packages and dependencies
       # By default, install:
-      # - ixmp, message_ix: from GitHub branches/tags per matrix.upstream-version (above)
+      # - ixmp, message_ix: from GitHub branches/tags per matrix.version.upstream (above)
       # - other dependencies including genno: from PyPI.
       #
       # To test against unreleased code (on `main`, or other branches
       # for open PRs), temporarily uncomment, add, or edit lines below
       # as needed. DO NOT merge such changes to `main`.
       run: |
-        # pip install --upgrade "genno @ git+https://github.com/khaeru/genno.git@main"
-        pip install --upgrade "ixmp @ git+https://github.com/iiasa/ixmp.git@${{ matrix.upstream.version }}"
-        pip install --upgrade "message-ix @ git+https://github.com/iiasa/message_ix.git@${{ matrix.upstream.version }}"
+        pip install --upgrade "ixmp @ git+https://github.com/iiasa/ixmp.git@${{ matrix.version.upstream }}"
+        pip install --upgrade "message-ix @ git+https://github.com/iiasa/message_ix.git@${{ matrix.version.upstream }}"
 
-        pip install .[docs,tests] ${{ matrix.upstream.extra-deps }}
+        pip install .[docs,tests] ${{ steps.extra-deps.outputs.value }}
 
-
-    - name: Install specific dask versions as workaround
-      if: ${{ matrix.upstream.dask-dataframe }}
-      run: |
-        # TEMPORARY Work around dask v2024.11.0;
-        # see https://github.com/khaeru/genno/issues/149
-        pip install "dask[dataframe] < 2024.11.0"
+        # TEMPORARY With Python 3.13 pyam-iamc resolves to 1.3.1, which in turn
+        # limits pint < 0.17. Override.
+        pip install --upgrade pint
 
     - name: Configure local data path
       run: |
@@ -153,7 +155,7 @@ jobs:
     steps:
     - uses: actions/checkout@v4
     - uses: actions/setup-python@v5
-      with: { python-version: "3.12" }
+      with: { python-version: "3.13" }
 
     - name: Force recreation of pre-commit virtual environment for mypy
       if: github.event_name == 'schedule'  # Comment this line to run on a PR
diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index 7ca4179146..283e5f3b93 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -10,7 +10,7 @@ repos:
     language: python
     entry: bash -c ". ${PRE_COMMIT_MYPY_VENV:-/dev/null}/bin/activate 2>/dev/null; mypy $0 $@; python -m pip list"
     additional_dependencies:
-    - mypy >= 1.11.0
+    - mypy >= 1.13.0
     - plotnine
     - pytest
     - sdmx1
@@ -20,7 +20,7 @@ repos:
     - "message-ix @ git+https://github.com/iiasa/message_ix.git@main"
     args: ["."]
 - repo: https://github.com/astral-sh/ruff-pre-commit
-  rev: v0.5.5
+  rev: v0.7.4
   hooks:
   - id: ruff
   - id: ruff-format
diff --git a/doc/whatsnew.rst b/doc/whatsnew.rst
index bacb8da0a0..1235f2a20e 100644
--- a/doc/whatsnew.rst
+++ b/doc/whatsnew.rst
@@ -4,8 +4,10 @@ What's new
 Next release
 ============
 
+- :mod:`message_ix_models` is tested and compatible with `Python 3.13 <https://www.python.org/downloads/release/python-3130/>`__ (:pull:`250`).
+- Support for Python 3.8 is dropped (:pull:`250`), as it has reached end-of-life.
 - Connect the water module to the cost module for cooling technologies (:pull:`245`).
-- Make setup of constraints for cooling technologies flexible and update solar csp tech. name (:pull:`242`). 
+- Make setup of constraints for cooling technologies flexible and update solar csp tech. name (:pull:`242`).
 - Fix the nexus/cooling function and add test for checking some input data (:pull:`236`).
 - Add :doc:`/project/circeular` project code and documentation (:pull:`232`).
 - Update water availability data and major code editing to allow a new test suite for the water module (:pull:`106`).
diff --git a/message_ix_models/model/build.py b/message_ix_models/model/build.py
index 303e85ab95..3858b207b9 100644
--- a/message_ix_models/model/build.py
+++ b/message_ix_models/model/build.py
@@ -1,5 +1,6 @@
 import logging
-from typing import Callable, Dict, List, Mapping, Optional, Union
+from collections.abc import Callable, Mapping
+from typing import Optional, Union
 
 import ixmp
 import pandas as pd
@@ -77,7 +78,7 @@ def apply_spec(  # noqa: C901
             pass
         maybe_check_out(scenario)
 
-    dump: Dict[str, pd.DataFrame] = {}  # Removed data
+    dump: dict[str, pd.DataFrame] = {}  # Removed data
 
     # Sort the list of sets by the number of dimensions; this places basic (non-indexed)
     # sets first. Elements for these sets must be added before elements for indexed
@@ -166,7 +167,7 @@ def apply_spec(  # noqa: C901
     )
 
 
-def ellipsize(elements: List) -> str:
+def ellipsize(elements: list) -> str:
     """Generate a short string representation of `elements`.
 
     If the list has more than 5 elements, only the first two and last two are shown,
diff --git a/message_ix_models/model/disutility.py b/message_ix_models/model/disutility.py
index 20bbb19ae8..0de792ae0c 100644
--- a/message_ix_models/model/disutility.py
+++ b/message_ix_models/model/disutility.py
@@ -1,9 +1,9 @@
 import logging
 from collections import defaultdict
+from collections.abc import Mapping, MutableMapping, Sequence
 from copy import copy
 from functools import partial
 from itertools import product
-from typing import List, Mapping, MutableMapping, Sequence
 
 import message_ix
 import pandas as pd
@@ -166,10 +166,10 @@ def data_conversion(info, spec: Spec) -> MutableMapping[str, pd.DataFrame]:
     )
 
     # Use the spec to retrieve information
-    technology: List[Code] = spec.add.set["technology"]
+    technology: list[Code] = spec.add.set["technology"]
 
     # Data to return
-    data0: Mapping[str, List[pd.DataFrame]] = defaultdict(list)
+    data0: Mapping[str, list[pd.DataFrame]] = defaultdict(list)
 
     # Loop over conversion technologies
     for t in technology:
diff --git a/message_ix_models/model/emissions.py b/message_ix_models/model/emissions.py
index d668b77929..592ab6d442 100644
--- a/message_ix_models/model/emissions.py
+++ b/message_ix_models/model/emissions.py
@@ -1,6 +1,6 @@
 import logging
 import re
-from typing import Optional, Tuple
+from typing import Optional
 
 import pandas as pd
 from genno import Quantity
@@ -153,7 +153,7 @@ def add_tax_emission(
         scen.add_par(name, data)
 
 
-def split_species(unit_expr: str) -> Tuple[str, Optional[str]]:
+def split_species(unit_expr: str) -> tuple[str, Optional[str]]:
     """Split `unit_expr` to an expression without a unit mention, and maybe species."""
     if match := re.fullmatch("(.*)(CO2|C)(.*)", unit_expr):
         return f"{match.group(1)}{match.group(3)}", match.group(2)
diff --git a/message_ix_models/model/macro.py b/message_ix_models/model/macro.py
index 036368e316..80cc99e8dc 100644
--- a/message_ix_models/model/macro.py
+++ b/message_ix_models/model/macro.py
@@ -5,10 +5,11 @@
 """
 
 import logging
+from collections.abc import Mapping
 from functools import lru_cache
 from itertools import product
 from pathlib import Path
-from typing import TYPE_CHECKING, List, Literal, Mapping, Optional, Union
+from typing import TYPE_CHECKING, Literal, Optional, Union
 
 import pandas as pd
 
@@ -29,7 +30,7 @@
 def generate(
     parameter: Literal["aeei", "config", "depr", "drate", "lotol"],
     context: "Context",
-    commodities: Union[List[str], List["Code"]] = COMMODITY,
+    commodities: Union[list[str], list["Code"]] = COMMODITY,
     value: Optional[float] = None,
 ) -> pd.DataFrame:
     """Generate uniform data for one :mod:`message_ix.macro` `parameter`.
diff --git a/message_ix_models/model/material/build.py b/message_ix_models/model/material/build.py
index 0ccac30770..8747a9e507 100644
--- a/message_ix_models/model/material/build.py
+++ b/message_ix_models/model/material/build.py
@@ -1,5 +1,6 @@
 import logging
-from typing import Any, Dict, Mapping
+from collections.abc import Mapping
+from typing import Any
 
 import message_ix
 import pandas as pd
@@ -206,7 +207,7 @@ def get_spec() -> Mapping[str, ScenarioInfo]:
 
 
 def make_spec(regions: str, materials: str or None = SPEC_LIST) -> Spec:
-    sets: Dict[str, Any] = dict()
+    sets: dict[str, Any] = dict()
     materials = ["common"] if not materials else materials
     # Overrides specific to regional versions
     tmp = dict()
diff --git a/message_ix_models/model/material/data_aluminum.py b/message_ix_models/model/material/data_aluminum.py
index 2cc9110538..16b0edfb47 100644
--- a/message_ix_models/model/material/data_aluminum.py
+++ b/message_ix_models/model/material/data_aluminum.py
@@ -1,5 +1,5 @@
 from collections import defaultdict
-from typing import Dict, Iterable, List
+from collections.abc import Iterable
 
 import message_ix
 import pandas as pd
@@ -69,7 +69,7 @@ def read_data_aluminum(
     return data_alu, data_alu_rel, data_aluminum_ts
 
 
-def gen_data_alu_ts(data: pd.DataFrame, nodes: list) -> Dict[str, pd.DataFrame]:
+def gen_data_alu_ts(data: pd.DataFrame, nodes: list) -> dict[str, pd.DataFrame]:
     """
     Generates time variable parameter data for aluminum sector
     Parameters
@@ -330,7 +330,7 @@ def gen_data_alu_const(
     glb_reg: str,
     years: Iterable,
     yv_ya: pd.DataFrame,
-    nodes: List[str],
+    nodes: list[str],
 ):
     results = defaultdict(list)
     for t in config["technology"]["add"]:
@@ -544,7 +544,7 @@ def gen_mock_demand_aluminum(scenario: message_ix.Scenario) -> pd.DataFrame:
     return demand2020_al
 
 
-def gen_data_alu_trade(scenario: message_ix.Scenario) -> Dict[str, pd.DataFrame]:
+def gen_data_alu_trade(scenario: message_ix.Scenario) -> dict[str, pd.DataFrame]:
     results = defaultdict(list)
 
     data_trade = pd.read_csv(
diff --git a/message_ix_models/model/material/data_methanol.py b/message_ix_models/model/material/data_methanol.py
index 4f0f08b43b..1e573917b2 100644
--- a/message_ix_models/model/material/data_methanol.py
+++ b/message_ix_models/model/material/data_methanol.py
@@ -1,5 +1,5 @@
 from ast import literal_eval
-from typing import TYPE_CHECKING, Dict, List
+from typing import TYPE_CHECKING
 
 import pandas as pd
 import yaml
@@ -30,7 +30,7 @@
 }
 
 
-def gen_data_methanol(scenario: "Scenario") -> Dict[str, pd.DataFrame]:
+def gen_data_methanol(scenario: "Scenario") -> dict[str, pd.DataFrame]:
     """
     Generates data for methanol industry model
 
@@ -94,8 +94,8 @@ def gen_data_methanol(scenario: "Scenario") -> Dict[str, pd.DataFrame]:
 def broadcast_nodes(
     df_bc_node: pd.DataFrame,
     df_final: pd.DataFrame,
-    node_cols: List[str],
-    node_cols_codes: Dict[str, pd.Series],
+    node_cols: list[str],
+    node_cols_codes: dict[str, pd.Series],
     i: int,
 ) -> pd.DataFrame:
     """
@@ -105,8 +105,8 @@ def broadcast_nodes(
     ----------
     df_bc_node: pd.DataFrame
     df_final: pd.DataFrame
-    node_cols: List[str]
-    node_cols_codes: Dict[str, pd.Series]
+    node_cols: list[str]
+    node_cols_codes: dict[str, pd.Series]
     i: int
     """
     if len(node_cols) == 1:
@@ -153,8 +153,8 @@ def broadcast_nodes(
 
 def broadcast_years(
     df_bc_node: pd.DataFrame,
-    yr_col_out: List[str],
-    yr_cols_codes: Dict[str, List[str]],
+    yr_col_out: list[str],
+    yr_cols_codes: dict[str, list[str]],
     col: str,
 ) -> pd.DataFrame:
     """
@@ -162,8 +162,8 @@ def broadcast_years(
     Parameters
     ----------
     df_bc_node: pd.DataFrame
-    yr_col_out: List[str]
-    yr_cols_codes: ict[str, List[str]]
+    yr_col_out: list[str]
+    yr_cols_codes: ict[str, list[str]]
     col: str
     """
     if len(yr_col_out) == 1:
diff --git a/message_ix_models/model/material/data_petro.py b/message_ix_models/model/material/data_petro.py
index e7fbe66263..7f64836f85 100644
--- a/message_ix_models/model/material/data_petro.py
+++ b/message_ix_models/model/material/data_petro.py
@@ -1,5 +1,4 @@
 from collections import defaultdict
-from typing import List, Set
 
 import message_ix
 import pandas as pd
@@ -166,7 +165,7 @@ def get_demand_t1_with_income_elasticity(
 
 
 def gen_data_petro_ts(
-    data_petro_ts: pd.DataFrame, results: dict[list], tec_ts: Set[str], nodes: List[str]
+    data_petro_ts: pd.DataFrame, results: dict[list], tec_ts: set[str], nodes: list[str]
 ) -> None:
     for t in tec_ts:
         common = dict(
@@ -239,7 +238,7 @@ def assign_input_outpt(
     rg: str,
     global_region: str,
     common: dict,
-    nodes: List[str],
+    nodes: list[str],
 ) -> pd.DataFrame:
     com = split[1]
     lev = split[2]
@@ -295,7 +294,7 @@ def assign_input_outpt(
     return df
 
 
-def broadcast_to_regions(df: pd.DataFrame, global_region: str, nodes: List[str]):
+def broadcast_to_regions(df: pd.DataFrame, global_region: str, nodes: list[str]):
     if "node_loc" in df.columns:
         if (
             len(set(df["node_loc"])) == 1
diff --git a/message_ix_models/model/material/data_steel.py b/message_ix_models/model/material/data_steel.py
index ac875b872c..24f6f640e6 100644
--- a/message_ix_models/model/material/data_steel.py
+++ b/message_ix_models/model/material/data_steel.py
@@ -1,5 +1,5 @@
 from collections import defaultdict
-from typing import Dict, Iterable, List
+from collections.abc import Iterable
 
 import message_ix
 import pandas as pd
@@ -119,7 +119,7 @@ def gen_mock_demand_steel(scenario: message_ix.Scenario) -> pd.DataFrame:
 
 
 def gen_data_steel_ts(
-    data_steel_ts: pd.DataFrame, results: Dict[str, list], t: str, nodes: List[str]
+    data_steel_ts: pd.DataFrame, results: dict[str, list], t: str, nodes: list[str]
 ):
     common = dict(
         time="year",
@@ -213,11 +213,11 @@ def gen_data_steel_ts(
 
 def get_data_steel_const(
     data_steel: pd.DataFrame,
-    results: Dict[str, list],
+    results: dict[str, list],
     params: Iterable,
     t: str,
     yv_ya: pd.DataFrame,
-    nodes: List[str],
+    nodes: list[str],
     global_region: str,
 ):
     for par in params:
diff --git a/message_ix_models/model/material/data_util.py b/message_ix_models/model/material/data_util.py
index 6bf5a8ad89..7b41a402c4 100644
--- a/message_ix_models/model/material/data_util.py
+++ b/message_ix_models/model/material/data_util.py
@@ -1,6 +1,7 @@
 import os
+from collections.abc import Mapping
 from functools import lru_cache
-from typing import TYPE_CHECKING, Literal, Mapping
+from typing import TYPE_CHECKING, Literal
 
 import ixmp
 import message_ix
diff --git a/message_ix_models/model/structure.py b/message_ix_models/model/structure.py
index d694748350..427e5056d5 100644
--- a/message_ix_models/model/structure.py
+++ b/message_ix_models/model/structure.py
@@ -1,10 +1,10 @@
 import logging
 import re
 from collections import ChainMap
+from collections.abc import Mapping, MutableMapping
 from copy import copy
 from functools import lru_cache
 from itertools import product
-from typing import Dict, List, Mapping, MutableMapping, Tuple
 
 import click
 import pandas as pd
@@ -20,7 +20,7 @@
 
 
 @lru_cache()
-def codelists(kind: str) -> List[str]:
+def codelists(kind: str) -> list[str]:
     """Return a valid IDs for code lists of `kind`.
 
     Parameters
@@ -32,7 +32,7 @@ def codelists(kind: str) -> List[str]:
 
 
 @lru_cache()
-def get_codes(name: str) -> List[Code]:
+def get_codes(name: str) -> list[Code]:
     """Return codes for the dimension/set `name` in MESSAGE-GLOBIOM scenarios.
 
     The information is read from :file:`data/{name}.yaml`, e.g.
@@ -101,7 +101,7 @@ def get_codelist(name: str) -> Codelist:
 
 
 @lru_cache()
-def get_region_codes(codelist: str) -> List[Code]:
+def get_region_codes(codelist: str) -> list[Code]:
     """Return the codes that are children of "World" in the specified `codelist`."""
     nodes = get_codes(f"node/{codelist}")
     return nodes[nodes.index(Code(id="World"))].child
@@ -109,7 +109,7 @@ def get_region_codes(codelist: str) -> List[Code]:
 
 def generate_product(
     data: Mapping, name: str, template: Code
-) -> Tuple[List[Code], Dict[str, xr.DataArray]]:
+) -> tuple[list[Code], dict[str, xr.DataArray]]:
     """Generates codes using a `template` by Cartesian product along ≥1 dimensions.
 
     :func:`generate_set_elements` is called for each of the `dims`, and these values
diff --git a/message_ix_models/model/transport/data.py b/message_ix_models/model/transport/data.py
index f736a58e4a..2e9a223a29 100644
--- a/message_ix_models/model/transport/data.py
+++ b/message_ix_models/model/transport/data.py
@@ -120,7 +120,7 @@ def dummy_supply(technologies: List["Code"], info, config) -> Dict[str, pd.DataF
         merge_data(
             result,
             make_source_tech(
-                info, dict(commodity=c, level=level, technology=t, **common), **values
+                info, dict(commodity=c, level=level, technology=t) | common, **values
             ),
         )
 
diff --git a/message_ix_models/model/transport/operator.py b/message_ix_models/model/transport/operator.py
index 8b96a8c05c..a2d62c70a7 100644
--- a/message_ix_models/model/transport/operator.py
+++ b/message_ix_models/model/transport/operator.py
@@ -989,8 +989,7 @@ def share_weight(
     yC: Dict[Any, Any] = dict(y=cfg.year_convergence)
 
     # Weights in y0 for all modes and nodes
-    # NB here and below, with Python 3.9 one could do: dict(t=modes, n=nodes) | y0
-    idx = dict(t=t_modes, n=nodes, **y0)
+    idx = dict(t=t_modes, n=nodes) | y0
     w0 = share.sel(idx) / (cost.sel(idx).sel(c="transport", drop=True) ** lamda)
 
     # Normalize to 1 across modes
@@ -1005,8 +1004,8 @@ def share_weight(
         ref_nodes = cfg.share_weight_convergence[node]
 
         # Indexers
-        _1 = dict(n=node, **yC)  # Same node, convergence year
-        _2 = dict(n=ref_nodes, **y0)  # Reference node(s), base year
+        _1 = dict(n=node) | yC  # Same node, convergence year
+        _2 = dict(n=ref_nodes) | y0  # Reference node(s), base year
 
         if ref_nodes:
             # Ratio between this node's GDP in yC and the mean of the reference nodes'
diff --git a/message_ix_models/model/water/build.py b/message_ix_models/model/water/build.py
index 40978fea1f..c097d4cc75 100644
--- a/message_ix_models/model/water/build.py
+++ b/message_ix_models/model/water/build.py
@@ -1,6 +1,6 @@
 import logging
+from collections.abc import Mapping
 from functools import lru_cache, partial
-from typing import Mapping
 
 import pandas as pd
 from sdmx.model.v21 import Code
diff --git a/message_ix_models/model/water/data/demands.py b/message_ix_models/model/water/data/demands.py
index 912398886b..249f3d314e 100644
--- a/message_ix_models/model/water/data/demands.py
+++ b/message_ix_models/model/water/data/demands.py
@@ -1,7 +1,8 @@
 """Prepare data for adding demands"""
 
 import os
-from typing import TYPE_CHECKING, Literal, Sequence, Union
+from collections.abc import Sequence
+from typing import TYPE_CHECKING, Literal, Union
 
 import numpy as np
 import pandas as pd
diff --git a/message_ix_models/model/water/utils.py b/message_ix_models/model/water/utils.py
index c6de5bd31b..aec2d486aa 100644
--- a/message_ix_models/model/water/utils.py
+++ b/message_ix_models/model/water/utils.py
@@ -2,7 +2,7 @@
 from collections import defaultdict
 from functools import lru_cache
 from itertools import product
-from typing import Optional, Tuple
+from typing import Optional
 
 import numpy as np
 import pandas as pd
@@ -125,13 +125,13 @@ def func(row: pd.Series):
 
 
 def map_yv_ya_lt(
-    periods: Tuple[int, ...], lt: int, ya: Optional[int] = None
+    periods: tuple[int, ...], lt: int, ya: Optional[int] = None
 ) -> pd.DataFrame:
     """All meaningful combinations of (vintage year, active year) given `periods`.
 
     Parameters
     ----------
-    periods : Tuple[int, ...]
+    periods : tuple[int, ...]
         A sequence of years.
     lt : int, lifetime
     ya : int, active year
diff --git a/message_ix_models/model/workflow.py b/message_ix_models/model/workflow.py
index 3b9da4b2e4..d5170afe7b 100644
--- a/message_ix_models/model/workflow.py
+++ b/message_ix_models/model/workflow.py
@@ -1,7 +1,7 @@
 """Common steps for workflows."""
 
 from dataclasses import dataclass, field
-from typing import TYPE_CHECKING, Any, Dict, Optional
+from typing import TYPE_CHECKING, Any, Optional
 
 from message_ix import Scenario
 
@@ -21,7 +21,7 @@ class Config(ConfigHelper):
 
     #: Information on an optional, other scenario from which to copy demand data in
     #: :func:`solve` using :func:`transfer_demands`. Default: empty, do nothing.
-    demand_scenario: Dict = field(default_factory=dict)
+    demand_scenario: dict = field(default_factory=dict)
 
     #: :obj:`True` to call :func:`.reserve_margin.res_marg.main` in :func:`solve`.
     reserve_margin: bool = True
@@ -31,7 +31,7 @@ class Config(ConfigHelper):
     #: To replicate the behaviour of the `macro_params` argument to
     #: :meth:`.engage.ScenarioRunner.run`, which in turn sets the `convergence_issues`
     #: argument to :meth:`.engage.ScenarioRunner.solve`, set max_adjustment to 0.1.
-    solve: Dict[str, Any] = field(
+    solve: dict[str, Any] = field(
         default_factory=lambda: dict(model="MESSAGE-MACRO", max_adjustment=0.2)
     )
 
diff --git a/message_ix_models/project/edits/__init__.py b/message_ix_models/project/edits/__init__.py
index da9dca5039..1d960ba53f 100644
--- a/message_ix_models/project/edits/__init__.py
+++ b/message_ix_models/project/edits/__init__.py
@@ -1,6 +1,7 @@
 import logging
 import sys
-from typing import TYPE_CHECKING, Any, Callable, List, Optional
+from collections.abc import Callable
+from typing import TYPE_CHECKING, Any, Optional
 
 import pandas as pd
 import sdmx
@@ -126,7 +127,7 @@ def generate_pasta_structures(
 
 def coords_to_codelists(
     qty: "AnyQuantity", *, id_transform: Optional[Callable] = str.upper, **kwargs
-) -> List["Codelist"]:
+) -> list["Codelist"]:
     """Convert the coordinates of `qty` to a collection of :class:`.Codelist`.
 
     .. todo:: Move upstream, to :mod:`genno`.
diff --git a/message_ix_models/project/engage/workflow.py b/message_ix_models/project/engage/workflow.py
index be44304c48..bb987f2664 100644
--- a/message_ix_models/project/engage/workflow.py
+++ b/message_ix_models/project/engage/workflow.py
@@ -10,7 +10,7 @@
 import logging
 from copy import copy, deepcopy
 from dataclasses import dataclass, field
-from typing import Dict, List, Literal, Optional, Tuple, Union
+from typing import Literal, Optional, Union
 
 from iam_units import convert_gwp
 from message_ix import Scenario
@@ -40,7 +40,7 @@ class PolicyConfig(Config):
     label: str = ""
 
     #: Which steps of the ENGAGE workflow to run. Empty list = don't run any steps.
-    steps: List[int] = field(default_factory=lambda: [1, 2, 3])
+    steps: list[int] = field(default_factory=lambda: [1, 2, 3])
 
     #: In :func:`step_1`, actual quantity of the carbon budget to be imposed , or the
     #: value "calc", in which case the value is calculated from :attr:`label` by
@@ -49,16 +49,16 @@ class PolicyConfig(Config):
 
     #: In :func:`step_3`, optional information on a second scenario from which to copy
     #: ``tax_emission`` data.
-    tax_emission_scenario: Dict = field(default_factory=dict)
+    tax_emission_scenario: dict = field(default_factory=dict)
 
     #: In :func:`step_3`, emission types or categories (``type_emission``) for which to
     #: apply values for ``tax_emission``.
-    step_3_type_emission: List[str] = field(default_factory=lambda: ["TCE_non-CO2"])
+    step_3_type_emission: list[str] = field(default_factory=lambda: ["TCE_non-CO2"])
 
 
 def calc_hist_cum_CO2(
     context: Context, scen: Scenario, info: ScenarioInfo
-) -> Tuple[float, float]:
+) -> tuple[float, float]:
     """Calculate historic CO2 emissions.
 
     Adapted from :meth:`.engage.scenario_runner.ScenarioRunner.calc_hist_cum_CO2`, with
diff --git a/message_ix_models/project/gea/data.py b/message_ix_models/project/gea/data.py
index 9a4c671280..6ebba7ac52 100644
--- a/message_ix_models/project/gea/data.py
+++ b/message_ix_models/project/gea/data.py
@@ -2,7 +2,7 @@
 
 import logging
 from functools import lru_cache
-from typing import TYPE_CHECKING, Dict, List, Set, Tuple
+from typing import TYPE_CHECKING
 
 import genno
 
@@ -96,7 +96,7 @@ def transform(self, c: "Computer", base_key: genno.Key) -> genno.Key:
         k = super().transform(c, base_key)
 
         # TODO Incorporate the following
-        def adapt_nodes(nodes: List["Code"]) -> Dict[str, str]:
+        def adapt_nodes(nodes: list["Code"]) -> dict[str, str]:
             """Convert `nodes` with IDs e.g. “R11_AFR” to a mapping.
 
             From e.g. “AFR” to “R11_AFR”.
@@ -107,7 +107,7 @@ def adapt_nodes(nodes: List["Code"]) -> Dict[str, str]:
 
 
 @lru_cache
-def get_model_scenario() -> Set[Tuple[str, str]]:
+def get_model_scenario() -> set[tuple[str, str]]:
     """Return a set of valid GEA (model name, scenario name) combinations.
 
     These are read from :file:`data/gea/model-scenario.json`.
diff --git a/message_ix_models/project/navigate/__init__.py b/message_ix_models/project/navigate/__init__.py
index 67ed2a5684..ef2a5d5378 100644
--- a/message_ix_models/project/navigate/__init__.py
+++ b/message_ix_models/project/navigate/__init__.py
@@ -2,12 +2,13 @@
 
 import logging
 import operator
+from collections.abc import Generator, Mapping
 from copy import deepcopy
 from dataclasses import asdict, dataclass, field, replace
 from enum import Flag, auto
 from functools import lru_cache, reduce
 from pathlib import Path
-from typing import Dict, Generator, List, Literal, Mapping, Optional, Union, cast
+from typing import Literal, Optional, Union, cast
 
 import ixmp
 import yaml
@@ -76,7 +77,7 @@ def parse(cls, value):
 #:   In the NAVIGATE workflow, the :attr:`demand_scenario` values (scenario info style,
 #:   a :class:`dict` of ``model`` name, ``scenario`` name, and optional ``version``) are
 #:   set in .navigate.workflow.generate().
-CLIMATE_POLICY: Dict[Optional[str], WfConfig] = {
+CLIMATE_POLICY: dict[Optional[str], WfConfig] = {
     # Default
     None: WfConfig(
         reserve_margin=False,
@@ -161,7 +162,7 @@ def parse(cls, value):
 }
 
 
-def _anno(names: str, climate_policy) -> List[Annotation]:
+def _anno(names: str, climate_policy) -> list[Annotation]:
     """Return the annotations given by `names` from :data:`_A`.
 
     Shorthand function used to prepare :data:`EXTRA_SCENARIOS`.
@@ -201,7 +202,7 @@ def _anno(names: str, climate_policy) -> List[Annotation]:
 
 
 @lru_cache()
-def _read() -> List[Code]:
+def _read() -> list[Code]:
     """Read the codes from the NAVIGATE workflow directory."""
     workflow_dir = Path(ixmp.config.get("navigate workflow dir")).expanduser().resolve()
 
@@ -212,7 +213,7 @@ def _read() -> List[Code]:
         _content = yaml.safe_load(f)
 
     # Transform into a form intelligible by as_codes()
-    content: Dict[str, Union[str, Code]] = {}
+    content: dict[str, Union[str, Code]] = {}
     for item in _content:
         if isinstance(item, str):
             content[item] = Code(id=item, name=item)
@@ -265,7 +266,7 @@ class Config:
     carbon_tax: float = 1000.0
 
     #: Other scenario from which to copy historical time series data for reporting.
-    copy_ts: Dict = field(default_factory=dict)
+    copy_ts: dict = field(default_factory=dict)
 
     #: Target data structure for submission prep
     dsd: Literal["iiasa-ece", "navigate"] = "navigate"
diff --git a/message_ix_models/report/__init__.py b/message_ix_models/report/__init__.py
index fd01006481..db6361dd3a 100644
--- a/message_ix_models/report/__init__.py
+++ b/message_ix_models/report/__init__.py
@@ -1,11 +1,12 @@
 import logging
+from collections.abc import Callable
 from contextlib import nullcontext
 from copy import deepcopy
 from functools import partial
 from importlib import import_module
 from operator import itemgetter
 from pathlib import Path
-from typing import Callable, List, Optional, Tuple, Union
+from typing import Optional, Union
 from warnings import warn
 
 import genno.config
@@ -43,7 +44,7 @@ def _(c: Reporter, info):
 
 
 #: List of callbacks for preparing the Reporter.
-CALLBACKS: List[Callable] = []
+CALLBACKS: list[Callable] = []
 
 
 @genno.config.handles("iamc")
@@ -298,7 +299,7 @@ def prepare_reporter(
     context: Context,
     scenario: Optional[Scenario] = None,
     reporter: Optional[Reporter] = None,
-) -> Tuple[Reporter, Key]:
+) -> tuple[Reporter, Key]:
     """Return a :class:`.Reporter` and `key` prepared to report a :class:`.Scenario`.
 
     Parameters
diff --git a/message_ix_models/report/compat.py b/message_ix_models/report/compat.py
index 9e0d198b1b..3f9f31c450 100644
--- a/message_ix_models/report/compat.py
+++ b/message_ix_models/report/compat.py
@@ -1,9 +1,10 @@
 """Compatibility code that emulates legacy reporting."""
 
 import logging
+from collections.abc import Mapping
 from functools import partial
 from itertools import chain, count
-from typing import TYPE_CHECKING, Any, Dict, List, Mapping, Optional
+from typing import TYPE_CHECKING, Any, Optional
 
 from genno import Key, Quantity, quote
 from genno.core.key import iter_keys, single_key
@@ -65,7 +66,7 @@ def anon(name: Optional[str] = None, dims: Optional[Key] = None) -> Key:
     return result.append(*getattr(dims, "dims", []))
 
 
-def get_techs(c: "Computer", prefix: str, kinds: Optional[str] = None) -> List[str]:
+def get_techs(c: "Computer", prefix: str, kinds: Optional[str] = None) -> list[str]:
     """Return a list of technologies.
 
     The list is assembled from lists in `c` with keys like "t::{prefix} {kind}",
@@ -88,7 +89,7 @@ def make_shorthand_function(
 
     def func(
         c: "Computer",
-        technologies: List[str],
+        technologies: list[str],
         *,
         name: Optional[str] = None,
         filters: Optional[dict] = None,
@@ -143,7 +144,7 @@ def func(
 
 def eff(
     c: "Computer",
-    technologies: List[str],
+    technologies: list[str],
     filters_in: Optional[dict] = None,
     filters_out: Optional[dict] = None,
 ) -> Key:
@@ -203,7 +204,7 @@ def pe_w_ccs_retro(
     return k6
 
 
-def prepare_techs(c: "Computer", technologies: List["Code"]) -> None:
+def prepare_techs(c: "Computer", technologies: list["Code"]) -> None:
     """Prepare sets of technologies in `c`.
 
     For each `key` → `expr` in :data:`TECH_FILTERS` and each technology :class:`Code`
@@ -214,14 +215,14 @@ def prepare_techs(c: "Computer", technologies: List["Code"]) -> None:
 
     These lists of technologies can be used directly or retrieve with :func:`get_techs`.
     """
-    result: Mapping[str, List[str]] = {k: list() for k in TECH_FILTERS}
+    result: Mapping[str, list[str]] = {k: list() for k in TECH_FILTERS}
 
     warned = set()  # Filters that raise some kind of Exception
 
     # Iterate over technologies
     for t in technologies:
         # Assemble information about `t` from its annotations
-        info: Dict[str, Any] = dict(id=t.id)
+        info: dict[str, Any] = dict(id=t.id)
         # Sector
         info["sector"] = str(t.get_annotation(id="sector").text)
         try:
diff --git a/message_ix_models/report/config.py b/message_ix_models/report/config.py
index 46eec60601..60385dc2fc 100644
--- a/message_ix_models/report/config.py
+++ b/message_ix_models/report/config.py
@@ -1,7 +1,7 @@
 import logging
 from dataclasses import InitVar, dataclass, field
 from pathlib import Path
-from typing import TYPE_CHECKING, Dict, Optional, Union
+from typing import TYPE_CHECKING, Optional, Union
 
 from message_ix_models.util import local_data_path, package_data_path
 from message_ix_models.util.config import ConfigHelper
@@ -30,7 +30,7 @@ class Config(ConfigHelper):
     cli_output: Optional[Path] = None
 
     #: Configuration to be handled by :mod:`genno.config`.
-    genno_config: Dict = field(default_factory=dict)
+    genno_config: dict = field(default_factory=dict)
 
     #: Key for the Quantity or computation to report.
     key: Optional["KeyLike"] = None
@@ -46,7 +46,7 @@ class Config(ConfigHelper):
 
     #: Keyword arguments for :func:`.report.legacy.iamc_report_hackathon.report`, plus
     #: the key "use", which should be :any:`True` if legacy reporting is to be used.
-    legacy: Dict = field(default_factory=lambda: dict(use=False, merge_hist=True))
+    legacy: dict = field(default_factory=lambda: dict(use=False, merge_hist=True))
 
     def __post_init__(self, from_file, _legacy) -> None:
         self.use_file(from_file)
diff --git a/message_ix_models/report/operator.py b/message_ix_models/report/operator.py
index bc2a0b416f..ae8c4cc40e 100644
--- a/message_ix_models/report/operator.py
+++ b/message_ix_models/report/operator.py
@@ -3,7 +3,8 @@
 import itertools
 import logging
 import re
-from typing import TYPE_CHECKING, Any, List, Mapping, Optional, Set, Tuple, Union
+from collections.abc import Mapping
+from typing import TYPE_CHECKING, Any, Optional, Union
 
 import ixmp
 import pandas as pd
@@ -42,8 +43,8 @@
 
 
 def codelist_to_groups(
-    codes: List["Code"], dim: str = "n"
-) -> Mapping[str, Mapping[str, List[str]]]:
+    codes: list["Code"], dim: str = "n"
+) -> Mapping[str, Mapping[str, list[str]]]:
     """Convert `codes` into a mapping from parent items to their children.
 
     The returned value is suitable for use with :func:`genno.operator.aggregate`.
@@ -87,7 +88,7 @@ def exogenous_data():
 @exogenous_data.helper
 def add_exogenous_data(
     func, c: "Computer", *, context=None, source=None, source_kw=None
-) -> Tuple["Key", ...]:
+) -> tuple["Key", ...]:
     """Prepare `c` to compute exogenous data from `source`."""
     from message_ix_models.tools.exo_data import prepare_computer
 
@@ -165,7 +166,7 @@ def make_output_path(config: Mapping, name: Union[str, "Path"]) -> "Path":
     return config["output_dir"].joinpath(name)
 
 
-def model_periods(y: List[int], cat_year: pd.DataFrame) -> List[int]:
+def model_periods(y: list[int], cat_year: pd.DataFrame) -> list[int]:
     """Return the elements of `y` beyond the firstmodelyear of `cat_year`.
 
     .. todo:: Move upstream, to :mod:`message_ix`.
@@ -213,7 +214,7 @@ def remove_ts(
 
 
 # Non-weak references to objects to keep them alive
-_FROM_URL_REF: Set[Any] = set()
+_FROM_URL_REF: set[Any] = set()
 
 
 def from_url(url: str, cls=ixmp.TimeSeries) -> ixmp.TimeSeries:
diff --git a/message_ix_models/report/plot.py b/message_ix_models/report/plot.py
index 51d405fb17..5ae08cff68 100644
--- a/message_ix_models/report/plot.py
+++ b/message_ix_models/report/plot.py
@@ -6,8 +6,9 @@
 
 import logging
 import re
+from collections.abc import Sequence
 from datetime import datetime
-from typing import TYPE_CHECKING, List, Optional, Sequence
+from typing import TYPE_CHECKING, Optional
 
 import genno.compat.plotnine
 import pandas as pd
@@ -52,7 +53,7 @@ class MyPlot(Plot):
     """
 
     #: 'Static' geoms: list of plotnine objects that are not dynamic.
-    static: List["plotnine.typing.PlotAddable"] = [
+    static: list["plotnine.typing.PlotAddable"] = [
         p9.theme(figure_size=(23.4, 16.5)),  # A3 paper in landscape [inches]
         # p9.theme(figure_size=(11.7, 8.3)),  # A4 paper in landscape
     ]
@@ -73,7 +74,7 @@ class MyPlot(Plot):
     #: List of regular expressions corresponding to :attr:`inputs`. These are passed as
     #: the `expr` argument to :func:`.filter_ts` to filter the entire set of time series
     #: data.
-    inputs_regex: List[re.Pattern] = []
+    inputs_regex: list[re.Pattern] = []
 
     @classmethod
     def add_tasks(
diff --git a/message_ix_models/report/sim.py b/message_ix_models/report/sim.py
index 087362cef6..439e83f836 100644
--- a/message_ix_models/report/sim.py
+++ b/message_ix_models/report/sim.py
@@ -2,11 +2,11 @@
 
 import logging
 from collections import ChainMap, defaultdict
-from collections.abc import Mapping
+from collections.abc import Mapping, Sequence
 from copy import deepcopy
 from functools import lru_cache
 from pathlib import Path
-from typing import TYPE_CHECKING, Any, Dict, List, Optional, Sequence, Union
+from typing import TYPE_CHECKING, Any, Optional, Union
 
 import pandas as pd
 from dask.core import quote
@@ -32,7 +32,7 @@
 log = logging.getLogger(__name__)
 
 
-def dims_of(info: "Item") -> Dict[str, str]:
+def dims_of(info: "Item") -> dict[str, str]:
     """Return a mapping from the full index names to short dimension IDs of `info`."""
     return {d: rename_dims().get(d, d) for d in (info.dims or info.coords or [])}
 
@@ -53,7 +53,7 @@ def to_simulate():
 
 
 def simulate_qty(
-    name: str, dims: List[str], item_data: Union[dict, pd.DataFrame]
+    name: str, dims: list[str], item_data: Union[dict, pd.DataFrame]
 ) -> Quantity:
     """Return simulated data for item `name`.
 
@@ -71,7 +71,7 @@ def simulate_qty(
         data: Mapping = ChainMap(item_data, defaultdict(lambda: None))
 
         # Arguments for pd.DataFrame constructor
-        args: Dict[str, Any] = dict(data={})
+        args: dict[str, Any] = dict(data={})
 
         # Flag if all values in `data` are scalars
         all_scalar = True
@@ -141,7 +141,7 @@ def data_from_file(path: Path, *, name: str, dims: Sequence[str]) -> Quantity:
 def add_simulated_solution(
     rep: Reporter,
     info: ScenarioInfo,
-    data: Optional[Dict] = None,
+    data: Optional[dict] = None,
     path: Optional[Path] = None,
 ):
     """Add a simulated model solution to `rep`.
diff --git a/message_ix_models/report/util.py b/message_ix_models/report/util.py
index 0826822679..99494c5a48 100644
--- a/message_ix_models/report/util.py
+++ b/message_ix_models/report/util.py
@@ -1,5 +1,6 @@
 import logging
-from typing import Dict, Iterable, Optional, Union
+from collections.abc import Iterable
+from typing import Optional, Union
 
 import pandas as pd
 from dask.core import quote
@@ -19,7 +20,7 @@
 #:
 #: - Applied to whole strings along each dimension.
 #: - These columns have :meth:`str.title` applied before these replacements.
-REPLACE_DIMS: Dict[str, Dict[str, str]] = {
+REPLACE_DIMS: dict[str, dict[str, str]] = {
     "c": {
         # in land_out, for CH4 emissions from GLOBIOM
         "Agri_Ch4": "GLOBIOM|Emissions|CH4 Emissions Total",
diff --git a/message_ix_models/testing/__init__.py b/message_ix_models/testing/__init__.py
index 216dee7fda..653c507ad5 100644
--- a/message_ix_models/testing/__init__.py
+++ b/message_ix_models/testing/__init__.py
@@ -2,11 +2,11 @@
 import os
 import shutil
 from base64 import b32hexencode
+from collections.abc import Generator
 from copy import deepcopy
 from pathlib import Path
 from random import randbytes
 from tempfile import TemporaryDirectory
-from typing import Generator
 
 import message_ix
 import pandas as pd
diff --git a/message_ix_models/tests/model/transport/test_ldv.py b/message_ix_models/tests/model/transport/test_ldv.py
index 578f63406b..bf1918fb5f 100644
--- a/message_ix_models/tests/model/transport/test_ldv.py
+++ b/message_ix_models/tests/model/transport/test_ldv.py
@@ -1,6 +1,6 @@
 import logging
+from collections.abc import Mapping
 from itertools import product
-from typing import List, Mapping, Tuple
 
 import pandas as pd
 import pytest
@@ -115,7 +115,7 @@ def include(arg):
 
     # Information about returned parameters
     # TODO Include unit checks, above, in this collection
-    par_info: Mapping[str, Tuple[bool, List[int], int]] = {
+    par_info: Mapping[str, tuple[bool, list[int], int]] = {
         "bound_new_capacity_lo": (False, [info.y0], 1),
         "bound_new_capacity_up": (False, info.Y, 1),
         "emission_factor": (True, None, None),
diff --git a/message_ix_models/tests/util/test_config.py b/message_ix_models/tests/util/test_config.py
index 409d5c1ddc..0d77cf21fb 100644
--- a/message_ix_models/tests/util/test_config.py
+++ b/message_ix_models/tests/util/test_config.py
@@ -1,5 +1,4 @@
 from dataclasses import dataclass, field
-from typing import Type
 
 import pytest
 
@@ -8,7 +7,7 @@
 
 class TestConfigHelper:
     @pytest.fixture
-    def cls(self) -> Type:
+    def cls(self) -> type:
         """A class which inherits from ConfigHelper."""
 
         @dataclass
@@ -20,7 +19,7 @@ class Config(ConfigHelper):
         return Config
 
     @pytest.fixture
-    def cls2(self, cls) -> Type:
+    def cls2(self, cls) -> type:
         """A class with an attribute."""
 
         @dataclass
diff --git a/message_ix_models/tests/util/test_sdmx.py b/message_ix_models/tests/util/test_sdmx.py
index febea39234..56c950e621 100644
--- a/message_ix_models/tests/util/test_sdmx.py
+++ b/message_ix_models/tests/util/test_sdmx.py
@@ -15,8 +15,9 @@ def test_eval_anno(caplog, recwarn):
 
     c.annotations.append(Annotation(id="foo", text="bar baz"))
 
-    with caplog.at_level(logging.DEBUG, logger="message_ix_models"), pytest.warns(
-        DeprecationWarning
+    with (
+        caplog.at_level(logging.DEBUG, logger="message_ix_models"),
+        pytest.warns(DeprecationWarning),
     ):
         assert "bar baz" == eval_anno(c, "foo")
 
diff --git a/message_ix_models/tools/costs/config.py b/message_ix_models/tools/costs/config.py
index d4023469a3..49bf4675dc 100644
--- a/message_ix_models/tools/costs/config.py
+++ b/message_ix_models/tools/costs/config.py
@@ -1,5 +1,5 @@
 from dataclasses import dataclass, field
-from typing import List, Literal, Optional
+from typing import Literal, Optional
 
 from message_ix_models import ScenarioInfo
 
@@ -99,12 +99,12 @@ def y0(self) -> int:
         return self._info.y0
 
     @property
-    def Y(self) -> List[int]:
+    def Y(self) -> list[int]:
         """List of model periods."""
         return self._info.Y
 
     @property
-    def seq_years(self) -> List[int]:
+    def seq_years(self) -> list[int]:
         """Similar to :attr:`Y`.
 
         This list of periods differs in that it:
diff --git a/message_ix_models/tools/costs/projections.py b/message_ix_models/tools/costs/projections.py
index b9172a1f84..2462868d15 100644
--- a/message_ix_models/tools/costs/projections.py
+++ b/message_ix_models/tools/costs/projections.py
@@ -1,6 +1,6 @@
 import logging
+from collections.abc import Mapping
 from itertools import product
-from typing import Mapping, Tuple
 
 import numpy as np
 import pandas as pd
@@ -335,7 +335,7 @@ def _predict(df: pd.DataFrame) -> pd.Series:
 
 def create_message_outputs(
     df_projections: pd.DataFrame, config: "Config"
-) -> Tuple[pd.DataFrame, pd.DataFrame]:
+) -> tuple[pd.DataFrame, pd.DataFrame]:
     """Create MESSAGEix outputs for investment and fixed costs.
 
     The returned data have the model periods given by :attr:`.Config.Y`.
@@ -522,7 +522,7 @@ def _compute_value(df: pd.DataFrame) -> pd.Series:
 
 def create_iamc_outputs(
     msg_inv: pd.DataFrame, msg_fix: pd.DataFrame
-) -> Tuple[pd.DataFrame, pd.DataFrame]:
+) -> tuple[pd.DataFrame, pd.DataFrame]:
     """Create IAMC outputs for investment and fixed costs.
 
     Parameters
diff --git a/message_ix_models/tools/costs/regional_differentiation.py b/message_ix_models/tools/costs/regional_differentiation.py
index da071ab32e..8957475d96 100644
--- a/message_ix_models/tools/costs/regional_differentiation.py
+++ b/message_ix_models/tools/costs/regional_differentiation.py
@@ -1,7 +1,8 @@
 import logging
+from collections.abc import Mapping
 from functools import lru_cache
 from itertools import product
-from typing import Literal, Mapping
+from typing import Literal
 
 import numpy as np
 import pandas as pd
diff --git a/message_ix_models/tools/exo_data.py b/message_ix_models/tools/exo_data.py
index 718f3ae836..ece3fc62ee 100644
--- a/message_ix_models/tools/exo_data.py
+++ b/message_ix_models/tools/exo_data.py
@@ -2,10 +2,11 @@
 
 import logging
 from abc import ABC, abstractmethod
+from collections.abc import Mapping
 from copy import deepcopy
 from operator import itemgetter
 from pathlib import Path
-from typing import Any, Dict, List, Literal, Mapping, Optional, Tuple, Type
+from typing import Any, Literal, Optional
 
 from genno import Computer, Key, Quantity, quote
 
@@ -32,7 +33,7 @@
 MEASURES = ("GDP", "POP")
 
 #: Known sources for data. Use :func:`register_source` to add to this collection.
-SOURCES: Dict[str, Type["ExoDataSource"]] = {}
+SOURCES: dict[str, type["ExoDataSource"]] = {}
 
 
 class ExoDataSource(ABC):
@@ -50,7 +51,7 @@ class ExoDataSource(ABC):
 
     #: Optional additional dimensions for the returned :class:`.Key`/:class:`.Quantity`.
     #: If not set by :meth:`.__init__`, the dimensions are :math:`(n, y)`.
-    extra_dims: Tuple[str, ...] = ()
+    extra_dims: tuple[str, ...] = ()
 
     #: :any:`True` if :meth:`.transform` should aggregate data on the |n| dimension.
     aggregate: bool = True
@@ -96,7 +97,7 @@ def __call__(self) -> Quantity:
         """
         raise NotImplementedError
 
-    def get_keys(self) -> Tuple[Key, Key]:
+    def get_keys(self) -> tuple[Key, Key]:
         """Return the target keys for the (1) raw and (2) transformed data.
 
         Subclasses **may** override this method to provide different targets keys. In
@@ -172,7 +173,7 @@ def prepare_computer(
     source_kw: Optional[Mapping] = None,
     *,
     strict: bool = True,
-) -> Tuple[Key, ...]:
+) -> tuple[Key, ...]:
     """Prepare `c` to compute GDP, population, or other exogenous data.
 
     Check each :class:`ExoDataSource` in :data:`SOURCES` to determine whether it
@@ -279,7 +280,7 @@ def prepare_computer(
     return tuple(keys)
 
 
-def register_source(cls: Type[ExoDataSource]) -> Type[ExoDataSource]:
+def register_source(cls: type[ExoDataSource]) -> type[ExoDataSource]:
     """Register :class:`.ExoDataSource` `cls` as a source of exogenous data."""
     if cls.id in SOURCES:
         raise ValueError(f"{SOURCES[cls.id]} already registered for id {cls.id!r}")
@@ -342,7 +343,7 @@ def iamc_like_data_for_query(
     query: str,
     *,
     archive_member: Optional[str] = None,
-    drop: Optional[List[str]] = None,
+    drop: Optional[list[str]] = None,
     non_iso_3166: Literal["keep", "discard"] = "discard",
     replace: Optional[dict] = None,
     unique: str = "MODEL SCENARIO VARIABLE UNIT",
diff --git a/message_ix_models/tools/iea/web.py b/message_ix_models/tools/iea/web.py
index a6092e84ae..64e77bdd76 100644
--- a/message_ix_models/tools/iea/web.py
+++ b/message_ix_models/tools/iea/web.py
@@ -2,9 +2,10 @@
 
 import logging
 import zipfile
+from collections.abc import Iterable
 from copy import copy
 from pathlib import Path
-from typing import TYPE_CHECKING, Any, Dict, Iterable, Optional
+from typing import TYPE_CHECKING, Any, Optional
 
 import pandas as pd
 from genno import Quantity
@@ -198,7 +199,7 @@ def iea_web_data_for_query(
 
         if path.suffix == ".TXT":  # pragma: no cover
             names_to_read.append(fwf_to_csv(path, progress=True))
-            args: Dict[str, Any] = dict(header=None, names=DIMS + ["Value"])
+            args: dict[str, Any] = dict(header=None, names=DIMS + ["Value"])
         else:
             names_to_read.append(path)
             args = dict(header=0, usecols=DIMS + ["Value"])
diff --git a/message_ix_models/tools/wb.py b/message_ix_models/tools/wb.py
index 2873b26f5d..2fea967269 100644
--- a/message_ix_models/tools/wb.py
+++ b/message_ix_models/tools/wb.py
@@ -2,8 +2,9 @@
 
 import logging
 from collections import defaultdict
+from collections.abc import MutableMapping
 from functools import lru_cache
-from typing import TYPE_CHECKING, Dict, MutableMapping, Optional
+from typing import TYPE_CHECKING, Optional
 
 import pandas as pd
 
@@ -18,7 +19,7 @@ def assign_income_groups(  # noqa: C901
     cl_node: "sdmx.model.common.Codelist",
     cl_income_group: "sdmx.model.common.Codelist",
     method: str = "population",
-    replace: Optional[Dict[str, str]] = None,
+    replace: Optional[dict[str, str]] = None,
 ) -> None:
     """Annotate `cl_node` with income groups.
 
@@ -283,8 +284,8 @@ def urn_for(name: str) -> str:
 
 
 def make_map(
-    source: Dict[str, str], expand_key_urn: bool = True, expand_value_urn: bool = False
-) -> Dict[str, str]:
+    source: dict[str, str], expand_key_urn: bool = True, expand_value_urn: bool = False
+) -> dict[str, str]:
     """Prepare the :py:`replace` parameter of :func:`assign_income_groups`.
 
     The result has one (`key`, `value`) for each in `source`.
diff --git a/message_ix_models/util/__init__.py b/message_ix_models/util/__init__.py
index 90263124e9..f0382a929c 100644
--- a/message_ix_models/util/__init__.py
+++ b/message_ix_models/util/__init__.py
@@ -1,23 +1,12 @@
 import logging
 from collections import ChainMap, defaultdict
+from collections.abc import Callable, Collection, Mapping, MutableMapping, Sequence
 from datetime import datetime
 from functools import partial, update_wrapper
 from importlib.metadata import version
 from itertools import count
 from pathlib import Path
-from typing import (
-    TYPE_CHECKING,
-    Callable,
-    Collection,
-    Dict,
-    List,
-    Mapping,
-    MutableMapping,
-    Optional,
-    Protocol,
-    Sequence,
-    Union,
-)
+from typing import TYPE_CHECKING, Optional, Protocol, Union
 
 import message_ix
 import pandas as pd
@@ -425,7 +414,7 @@ def make_io(src, dest, efficiency, on="input", **kwargs):
 
 def make_matched_dfs(
     base: Union[MutableMapping, pd.DataFrame], **par_value: Union[float, pint.Quantity]
-) -> Dict[str, pd.DataFrame]:
+) -> dict[str, pd.DataFrame]:
     """Return data frames derived from `base` for multiple parameters.
 
     Creates one data frame per keyword argument.
@@ -471,7 +460,7 @@ def make_matched_dfs(
 
 def make_source_tech(
     info: Union[message_ix.Scenario, ScenarioInfo], common, **values
-) -> Dict[str, pd.DataFrame]:
+) -> dict[str, pd.DataFrame]:
     """Return parameter data for a ‘source’ technology.
 
     The technology has no inputs; its output commodity and/or level are determined by
@@ -612,7 +601,7 @@ def marker(test_func):
 
 def path_fallback(
     *parts: Union[str, Path],
-    where: Union[str, List[Union[str, Path]]] = "",
+    where: Union[str, list[Union[str, Path]]] = "",
 ) -> Path:
     """Locate a path constructed from `parts` found in the first of several directories.
 
@@ -783,7 +772,7 @@ def strip_par_data(  # noqa: C901
     set_name: str,
     element: str,
     dry_run: bool = False,
-    dump: Optional[Dict[str, pd.DataFrame]] = None,
+    dump: Optional[dict[str, pd.DataFrame]] = None,
 ) -> int:
     """Remove `element` from `set_name` in scenario, optionally dumping to `dump`.
 
diff --git a/message_ix_models/util/_convert_units.py b/message_ix_models/util/_convert_units.py
index 815e97b464..fba96366c8 100644
--- a/message_ix_models/util/_convert_units.py
+++ b/message_ix_models/util/_convert_units.py
@@ -1,4 +1,5 @@
-from typing import Mapping, Optional, Tuple
+from collections.abc import Mapping
+from typing import Optional
 from warnings import catch_warnings, filterwarnings
 
 import pandas as pd
@@ -25,7 +26,7 @@ def series_of_pint_quantity(*args, **kwargs) -> pd.Series:
 
 def convert_units(
     s: pd.Series,
-    unit_info: Mapping[str, Tuple[float, str, Optional[str]]],
+    unit_info: Mapping[str, tuple[float, str, Optional[str]]],
     store="magnitude",
 ) -> pd.Series:
     """Convert units of `s`, for use with :meth:`~pandas.DataFrame.apply`.
diff --git a/message_ix_models/util/_logging.py b/message_ix_models/util/_logging.py
index 49f5a2cf6e..20543b8725 100644
--- a/message_ix_models/util/_logging.py
+++ b/message_ix_models/util/_logging.py
@@ -11,7 +11,7 @@
 from datetime import datetime, timedelta, timezone
 from queue import SimpleQueue
 from time import process_time
-from typing import Dict, Optional, Union, cast
+from typing import Optional, Union, cast
 from warnings import warn
 
 # NB mark_time, preserve_log_level, and silence_log are exposed by util/__init__.py
@@ -26,7 +26,7 @@
 log = logging.getLogger(__name__)
 
 # References to handlers
-_HANDLER: Dict[str, logging.Handler] = dict()
+_HANDLER: dict[str, logging.Handler] = dict()
 
 # For mark_time()
 _TIMES = []
diff --git a/message_ix_models/util/cache.py b/message_ix_models/util/cache.py
index 5509d2350c..0b35d74244 100644
--- a/message_ix_models/util/cache.py
+++ b/message_ix_models/util/cache.py
@@ -12,8 +12,9 @@
 
 import json
 import logging
+from collections.abc import Callable
 from dataclasses import asdict, is_dataclass
-from typing import TYPE_CHECKING, Callable, Set
+from typing import TYPE_CHECKING
 
 import genno.caching
 import ixmp
@@ -34,7 +35,7 @@
 SKIP_CACHE = False
 
 # Paths already logged, to decrease verbosity
-PATHS_SEEN: Set["Path"] = set()
+PATHS_SEEN: set["Path"] = set()
 
 
 # Show genno how to hash function arguments seen in message_ix_models
diff --git a/message_ix_models/util/click.py b/message_ix_models/util/click.py
index c6194517c7..849d9da3d9 100644
--- a/message_ix_models/util/click.py
+++ b/message_ix_models/util/click.py
@@ -5,11 +5,12 @@
 
 import logging
 import sys
+from collections.abc import Callable, Mapping
 from contextlib import contextmanager
 from dataclasses import dataclass, field
 from datetime import datetime
 from pathlib import Path
-from typing import Callable, List, Literal, Mapping, Optional, Union, cast
+from typing import Literal, Optional, Union, cast
 
 import click
 import click.testing
@@ -230,9 +231,9 @@ def temporary_command(group: "click.Group", command: "click.Command"):
 
 def urls_from_file(
     context: Union[click.Context, Context], param, value
-) -> List[ScenarioInfo]:
+) -> list[ScenarioInfo]:
     """Callback to parse scenario URLs from `value`."""
-    si: List[ScenarioInfo] = []
+    si: list[ScenarioInfo] = []
 
     if value is None:
         return si
@@ -416,7 +417,7 @@ def invoke_subprocess(self, *args, **kwargs) -> click.testing.Result:
         import subprocess
 
         assert 1 == len(args)
-        all_args: List[str] = [sys.executable, "-m", self.cli_module, *args[0]]
+        all_args: list[str] = [sys.executable, "-m", self.cli_module, *args[0]]
 
         # Run; capture in a subprocess.CompletedProcess
         cp = subprocess.run(all_args, capture_output=True, env=self.env, **kwargs)
diff --git a/message_ix_models/util/common.py b/message_ix_models/util/common.py
index 0d0275be21..fe4d501ec4 100644
--- a/message_ix_models/util/common.py
+++ b/message_ix_models/util/common.py
@@ -1,7 +1,8 @@
 import logging
 from abc import abstractmethod
+from collections.abc import Mapping, Sequence
 from pathlib import Path
-from typing import Any, Dict, Mapping, Optional, Sequence, Tuple, cast
+from typing import Any, Optional, cast
 
 import pandas as pd
 from genno import Quantity
@@ -23,10 +24,10 @@
 MESSAGE_MODELS_PATH = Path(__file__).parents[1]
 
 #: Package data already loaded with :func:`load_package_data`.
-PACKAGE_DATA: Dict[str, Any] = dict()
+PACKAGE_DATA: dict[str, Any] = dict()
 
 #: Data already loaded with :func:`load_private_data`.
-PRIVATE_DATA: Dict[str, Any] = dict()
+PRIVATE_DATA: dict[str, Any] = dict()
 
 
 __all__ = [
@@ -106,7 +107,7 @@ class MappingAdapter(Adapter):
 
     maps: Mapping
 
-    def __init__(self, maps: Mapping[str, Sequence[Tuple[str, str]]]):
+    def __init__(self, maps: Mapping[str, Sequence[tuple[str, str]]]):
         self.maps = maps
 
     def adapt(self, qty: Quantity) -> Quantity:
@@ -126,7 +127,7 @@ def adapt(self, qty: Quantity) -> Quantity:
 
 
 def _load(
-    var: Dict, base_path: Path, *parts: str, default_suffix: Optional[str] = None
+    var: dict, base_path: Path, *parts: str, default_suffix: Optional[str] = None
 ) -> Any:
     """Helper for :func:`.load_package_data` and :func:`.load_private_data`."""
     key = " ".join(parts)
diff --git a/message_ix_models/util/compat/message_data/utilities.py b/message_ix_models/util/compat/message_data/utilities.py
index d2fd07144e..f5a6274597 100644
--- a/message_ix_models/util/compat/message_data/utilities.py
+++ b/message_ix_models/util/compat/message_data/utilities.py
@@ -17,7 +17,7 @@
 
 def closest(List, K):
     """Finds the member of a list closest to a value (k)"""
-    return List[min(range(len(List)), key=lambda i: abs(List[i] - K))]
+    return list[min(range(len(List)), key=lambda i: abs(list[i] - K))]
 
 
 def f_index(df1, df2):
@@ -46,7 +46,7 @@ def idx_memb(List, x, distance):
     """Retrurns the member of the list with distance from x"""
 
     if List.index(x) + distance < len(List):
-        return List[List.index(x) + distance]
+        return list[List.index(x) + distance]
     else:
         return False
 
diff --git a/message_ix_models/util/config.py b/message_ix_models/util/config.py
index c76919385c..4dabdb78b3 100644
--- a/message_ix_models/util/config.py
+++ b/message_ix_models/util/config.py
@@ -1,10 +1,11 @@
 import logging
 import os
 import pickle
+from collections.abc import Mapping, MutableMapping, Sequence
 from dataclasses import asdict, dataclass, field, fields, is_dataclass, replace
 from hashlib import blake2s
 from pathlib import Path
-from typing import Any, Hashable, List, Mapping, MutableMapping, Optional, Sequence, Set
+from typing import Any, Hashable, Optional
 
 import ixmp
 
@@ -45,7 +46,7 @@ class ConfigHelper:
     """
 
     @classmethod
-    def _fields(cls) -> Set[str]:
+    def _fields(cls) -> set[str]:
         """Names of fields in `cls`."""
         result = set(dir(cls))
         if is_dataclass(cls):
@@ -175,7 +176,7 @@ class Config:
     scenario_info: MutableMapping[str, str] = field(default_factory=dict)
 
     #: Like `scenario_info`, but a list for operations affecting multiple scenarios.
-    scenarios: List[ScenarioInfo] = field(default_factory=list)
+    scenarios: list[ScenarioInfo] = field(default_factory=list)
 
     #: Like :attr:`platform_info`, used by e.g. :meth:`.clone_to_dest`.
     dest_platform: MutableMapping[str, str] = field(default_factory=dict)
diff --git a/message_ix_models/util/context.py b/message_ix_models/util/context.py
index d384cba4f1..69e5e871dd 100644
--- a/message_ix_models/util/context.py
+++ b/message_ix_models/util/context.py
@@ -4,7 +4,6 @@
 from copy import deepcopy
 from dataclasses import fields
 from pathlib import Path
-from typing import List
 
 import ixmp
 import message_ix
@@ -16,7 +15,7 @@
 log = logging.getLogger(__name__)
 
 #: List of Context instances, from first created to last.
-_CONTEXTS: List["Context"] = []
+_CONTEXTS: list["Context"] = []
 
 
 # Configuration keys which can be accessed directly on Context.
diff --git a/message_ix_models/util/ixmp.py b/message_ix_models/util/ixmp.py
index ffb5d4628c..aaa9407b07 100644
--- a/message_ix_models/util/ixmp.py
+++ b/message_ix_models/util/ixmp.py
@@ -1,5 +1,3 @@
-from typing import Dict
-
 try:
     # ixmp 3.8.0 and later
     from ixmp.report.util import get_reversed_rename_dims
@@ -38,7 +36,7 @@ def discard_on_error(*args):
 ]
 
 
-def rename_dims() -> Dict[str, str]:
+def rename_dims() -> dict[str, str]:
     """Access :data:`.ixmp.report.common.RENAME_DIMS`.
 
     This provides backwards-compatibility with ixmp versions 3.7.0 and earlier. It can
diff --git a/message_ix_models/util/node.py b/message_ix_models/util/node.py
index 4845a32905..90dc363207 100644
--- a/message_ix_models/util/node.py
+++ b/message_ix_models/util/node.py
@@ -1,7 +1,8 @@
 """Utilities for nodes."""
 
 import logging
-from typing import List, Sequence, Union
+from collections.abc import Sequence
+from typing import Union
 
 from message_ix import Scenario
 from sdmx.model.v21 import Code
@@ -124,7 +125,7 @@ def identify_nodes(scenario: Scenario) -> str:
         return id
 
 
-def nodes_ex_world(nodes: Sequence[Union[str, Code]]) -> List[Union[str, Code]]:
+def nodes_ex_world(nodes: Sequence[Union[str, Code]]) -> list[Union[str, Code]]:
     """Exclude "World" and anything containing "GLB" from `nodes`.
 
     May also be used as a genno (reporting) operator.
diff --git a/message_ix_models/util/pooch.py b/message_ix_models/util/pooch.py
index 38e3de0cdf..7215635cc5 100644
--- a/message_ix_models/util/pooch.py
+++ b/message_ix_models/util/pooch.py
@@ -1,8 +1,9 @@
 """Utilities for using :doc:`Pooch <pooch:about>`."""
 
 import logging
+from collections.abc import Mapping
 from pathlib import Path
-from typing import Any, Mapping, Optional, Tuple
+from typing import Any, Optional
 
 import click
 import pooch
@@ -152,7 +153,7 @@ def __call__(self, fname, action, pooch):
 
 def fetch(
     pooch_args: dict, *, extra_cache_path: Optional[str] = None, **fetch_kwargs
-) -> Tuple[Path, ...]:
+) -> tuple[Path, ...]:
     """Create a :class:`~pooch.Pooch` instance and fetch a single file.
 
     Files are stored under the directory identified by :meth:`.Context.get_cache_path`,
diff --git a/message_ix_models/util/scenarioinfo.py b/message_ix_models/util/scenarioinfo.py
index 81c21250dd..e737a1a678 100644
--- a/message_ix_models/util/scenarioinfo.py
+++ b/message_ix_models/util/scenarioinfo.py
@@ -5,7 +5,7 @@
 from collections import defaultdict
 from dataclasses import InitVar, dataclass, field
 from itertools import product
-from typing import TYPE_CHECKING, Dict, List, Optional
+from typing import TYPE_CHECKING, Optional
 
 import pandas as pd
 import pint
@@ -79,10 +79,10 @@ class ScenarioInfo:
     version: Optional[int] = None
 
     #: Elements of :mod:`ixmp`/:mod:`message_ix` sets.
-    set: Dict[str, List] = field(default_factory=lambda: defaultdict(list))
+    set: dict[str, list] = field(default_factory=lambda: defaultdict(list))
 
     #: Elements of :mod:`ixmp`/:mod:`message_ix` parameters.
-    par: Dict[str, pd.DataFrame] = field(default_factory=dict)
+    par: dict[str, pd.DataFrame] = field(default_factory=dict)
 
     #: First model year, if set, else ``Y[0]``.
     y0: int = -1
@@ -161,7 +161,7 @@ def N(self):
         return list(map(str, self.set["node"]))
 
     @property
-    def Y(self) -> List[int]:
+    def Y(self) -> list[int]:
         """Elements of the set 'year' that are >= the first model year."""
         return list(filter(lambda y: y >= self.y0, self.set["year"]))
 
@@ -280,7 +280,7 @@ def io_units(
             )
         return c / t
 
-    def year_from_codes(self, codes: List[sdmx_model.Code]):
+    def year_from_codes(self, codes: list[sdmx_model.Code]):
         """Update using a list of `codes`.
 
         The following are updated:
@@ -326,7 +326,7 @@ def year_from_codes(self, codes: List[sdmx_model.Code]):
             log.debug("Discard existing 'duration_period' elements")
 
         fmy_set = False
-        duration_period: List[Dict] = []
+        duration_period: list[dict] = []
 
         # TODO use sorted() here once supported by sdmx
         for code in codes:
diff --git a/message_ix_models/util/sdmx.py b/message_ix_models/util/sdmx.py
index acfbb84538..53aeb18148 100644
--- a/message_ix_models/util/sdmx.py
+++ b/message_ix_models/util/sdmx.py
@@ -1,11 +1,12 @@
 """Utilities for handling objects from :mod:`sdmx`."""
 
 import logging
+from collections.abc import Mapping
 from datetime import datetime
 from enum import Enum, Flag
 from importlib.metadata import version
 from pathlib import Path
-from typing import TYPE_CHECKING, Dict, List, Mapping, Optional, Union
+from typing import TYPE_CHECKING, Optional, Union
 from warnings import warn
 
 import sdmx
@@ -27,8 +28,8 @@
 
 # FIXME Reduce complexity from 13 → ≤11
 def as_codes(  # noqa: C901
-    data: Union[List[str], Dict[str, CodeLike]],
-) -> List[Code]:
+    data: Union[list[str], dict[str, CodeLike]],
+) -> list[Code]:
     """Convert `data` to a :class:`list` of :class:`.Code` objects.
 
     Various inputs are accepted:
@@ -38,7 +39,7 @@ def as_codes(  # noqa: C901
       further :class:`dict` with keys matching other Code attributes.
     """
     # Assemble results as a dictionary
-    result: Dict[str, Code] = {}
+    result: dict[str, Code] = {}
 
     if isinstance(data, list):
         # FIXME typing ignored temporarily for PR#9
diff --git a/message_ix_models/workflow.py b/message_ix_models/workflow.py
index a884cec9a3..b7743e4a4b 100644
--- a/message_ix_models/workflow.py
+++ b/message_ix_models/workflow.py
@@ -2,16 +2,8 @@
 
 import logging
 import re
-from typing import (
-    TYPE_CHECKING,
-    Callable,
-    List,
-    Literal,
-    Mapping,
-    Optional,
-    Tuple,
-    Union,
-)
+from collections.abc import Callable, Mapping
+from typing import TYPE_CHECKING, Literal, Optional, Union
 
 from genno import Computer
 from message_ix import Scenario
@@ -207,7 +199,7 @@ def add_step(
         # Add to the Computer; return the name of the added step
         return str(self.add_single(name, step, "context", base, strict=True))
 
-    def run(self, name_or_names: Union[str, List[str]]):
+    def run(self, name_or_names: Union[str, list[str]]):
         """Run all workflow steps necessary to produce `name_or_names`.
 
         Parameters
@@ -247,7 +239,7 @@ def truncate(self, name: str):
 
     def guess_target(
         self, step_name: str, kind: Literal["platform", "scenario"] = "scenario"
-    ) -> Tuple[Mapping, str]:
+    ) -> tuple[Mapping, str]:
         """Traverse the graph looking for non-empty platform_info/scenario_info.
 
         Returns the info, and the step name containing it. Usually, this will identify
diff --git a/pyproject.toml b/pyproject.toml
index 9e477826dc..59f38e3361 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -20,16 +20,16 @@ classifiers = [
   "Operating System :: OS Independent",
   "Programming Language :: Python",
   "Programming Language :: Python :: 3",
-  "Programming Language :: Python :: 3.8",
   "Programming Language :: Python :: 3.9",
   "Programming Language :: Python :: 3.10",
   "Programming Language :: Python :: 3.11",
   "Programming Language :: Python :: 3.12",
+  "Programming Language :: Python :: 3.13",
   "Programming Language :: R",
   "Topic :: Scientific/Engineering",
   "Topic :: Scientific/Engineering :: Information Analysis",
 ]
-requires-python = ">=3.8"
+requires-python = ">=3.9"
 dependencies = [
   "click",
   "colorama",
@@ -152,7 +152,12 @@ markers = [
 ]
 
 [tool.ruff]
-exclude = ["message_ix_models/report/legacy/", "message_ix_models/util/compat/message_data/"]
+exclude = [
+  "doc/_static/png_source_files/Land-use_emulator_figures.ipynb",
+  "message_ix_models/model/material/report/Historical Power Sector Stock Reporting-.ipynb",
+  "message_ix_models/report/legacy/",
+  "message_ix_models/util/compat/message_data/",
+]
 
 [tool.ruff.lint]
 select = ["C9", "E", "F", "I", "W"]