diff --git a/.github/workflows/matrix-all.yml b/.github/workflows/matrix-all.yml
deleted file mode 100644
index cc8e849b0..000000000
--- a/.github/workflows/matrix-all.yml
+++ /dev/null
@@ -1,41 +0,0 @@
-# Generated and maintained by the exasol-toolbox.
-# Last generated with exasol-toolbox version 8.1.1.
-name: Build Matrix (All Versions)
-
-on:
-  workflow_call:
-    outputs:
-      matrix:
-        description: "Generates the all versions build matrix"
-        value: ${{ jobs.set-matrix-all.outputs.matrix }}
-
-jobs:
-  set-matrix-all:
-    runs-on: "ubuntu-24.04"
-    permissions:
-      contents: read
-    steps:
-      - name: Check out Repository
-        id: check-out-repository
-        uses: actions/checkout@v6
-        with:
-          persist-credentials: false
-
-      - name: Set up Python & Poetry Environment
-        id: set-up-python-and-poetry-environment
-        uses: exasol/python-toolbox/.github/actions/python-environment@v8
-        with:
-          python-version: "3.10"
-          poetry-version: "2.3.0"
-
-      - name: Generate Matrix
-        id: generate-matrix
-        run: poetry run -- nox -s matrix:all
-
-      - name: Set Matrix
-        id: set-matrix
-        run: |
-          echo "matrix=$(poetry run -- nox -s matrix:all)" >> $GITHUB_OUTPUT
-
-    outputs:
-      matrix: ${{ steps.set-matrix.outputs.matrix }}
diff --git a/.github/workflows/matrix-exasol.yml b/.github/workflows/matrix-exasol.yml
deleted file mode 100644
index bab0ffb02..000000000
--- a/.github/workflows/matrix-exasol.yml
+++ /dev/null
@@ -1,41 +0,0 @@
-# Generated and maintained by the exasol-toolbox.
-# Last generated with exasol-toolbox version 8.1.1.
-name: Build Matrix (Exasol)
-
-on:
-  workflow_call:
-    outputs:
-      matrix:
-        description: "Generates the exasol version build matrix"
-        value: ${{ jobs.set-matrix-exasol.outputs.matrix }}
-
-jobs:
-  set-matrix-exasol:
-    runs-on: "ubuntu-24.04"
-    permissions:
-      contents: read
-    steps:
-      - name: Check out Repository
-        id: check-out-repository
-        uses: actions/checkout@v6
-        with:
-          persist-credentials: false
-
-      - name: Set up Python & Poetry Environment
-        id: set-up-python-and-poetry-environment
-        uses: exasol/python-toolbox/.github/actions/python-environment@v8
-        with:
-          python-version: "3.10"
-          poetry-version: "2.3.0"
-
-      - name: Generate Matrix
-        id: generate-matrix
-        run: poetry run -- nox -s matrix:exasol
-
-      - name: Set Matrix
-        id: set-matrix
-        run: |
-          echo "matrix=$(poetry run -- nox -s matrix:exasol)" >> $GITHUB_OUTPUT
-
-    outputs:
-      matrix: ${{ steps.set-matrix.outputs.matrix }}
diff --git a/.github/workflows/matrix-python.yml b/.github/workflows/matrix-python.yml
deleted file mode 100644
index c671c36f3..000000000
--- a/.github/workflows/matrix-python.yml
+++ /dev/null
@@ -1,41 +0,0 @@
-# Generated and maintained by the exasol-toolbox.
-# Last generated with exasol-toolbox version 8.1.1.
-name: Build Matrix (Python)
-
-on:
-  workflow_call:
-    outputs:
-      matrix:
-        description: "Generates the python version build matrix"
-        value: ${{ jobs.set-matrix-python.outputs.matrix }}
-
-jobs:
-  set-matrix-python:
-    runs-on: "ubuntu-24.04"
-    permissions:
-      contents: read
-    steps:
-      - name: Check out Repository
-        id: check-out-repository
-        uses: actions/checkout@v6
-        with:
-          persist-credentials: false
-
-      - name: Set up Python & Poetry Environment
-        id: set-up-python-and-poetry-environment
-        uses: exasol/python-toolbox/.github/actions/python-environment@v8
-        with:
-          python-version: "3.10"
-          poetry-version: "2.3.0"
-
-      - name: Generate Matrix
-        id: generate-matrix
-        run: poetry run -- nox -s matrix:python
-
-      - name: Set Matrix
-        id: set-matrix
-        run: |
-          echo "matrix=$(poetry run -- nox -s matrix:python)" >> $GITHUB_OUTPUT
-
-    outputs:
-      matrix: ${{ steps.set-matrix.outputs.matrix }}
diff --git a/.github/workflows/matrix.yml b/.github/workflows/matrix.yml
new file mode 100644
index 000000000..0f73f1285
--- /dev/null
+++ b/.github/workflows/matrix.yml
@@ -0,0 +1,79 @@
+# Generated and maintained by the exasol-toolbox.
+# Last generated with exasol-toolbox version 8.1.1.
+name: Build Matrix
+
+on:
+  workflow_call:
+    inputs:
+      matrix_keys_json:
+        description: "JSON array of BaseConfig keys to include in the generated matrix output."
+        required: true
+        type: string
+    outputs:
+      matrix:
+        description: "Generates the requested build matrix"
+        value: ${{ jobs.set-matrix.outputs.matrix }}
+
+jobs:
+  set-matrix:
+    runs-on: "ubuntu-24.04"
+    permissions:
+      contents: read
+    steps:
+      - name: Check out Repository
+        id: check-out-repository
+        uses: actions/checkout@v6
+        with:
+          persist-credentials: false
+
+      - name: Set up Python & Poetry Environment
+        id: set-up-python-and-poetry-environment
+        uses: exasol/python-toolbox/.github/actions/python-environment@v8
+        with:
+          python-version: "3.10"
+          poetry-version: "2.3.0"
+
+      - name: Parse Matrix Keys
+        id: parse-matrix-keys
+        env:
+          MATRIX_KEYS_JSON: ${{ inputs.matrix_keys_json }}
+        run: |
+          python - <<'PY'
+          import json
+          import os
+
+          matrix_keys = json.loads(os.environ["MATRIX_KEYS_JSON"])
+          with open(os.environ["GITHUB_OUTPUT"], "a", encoding="utf-8") as output_file:
+              print(f"matrix_keys_json={json.dumps(matrix_keys)}", file=output_file)
+          PY
+
+      - name: Generate Matrix
+        id: set-matrix
+        env:
+          MATRIX_KEYS_JSON: ${{ steps.parse-matrix-keys.outputs.matrix_keys_json }}
+        run: |
+          python - <<'PY'
+          import json
+          import os
+          import subprocess
+
+          matrix_keys = json.loads(os.environ["MATRIX_KEYS_JSON"])
+          matrix_json = subprocess.check_output(
+              [
+                  "poetry",
+                  "run",
+                  "--",
+                  "nox",
+                  "-s",
+                  "matrix:generate",
+                  "--",
+                  *matrix_keys,
+              ],
+              text=True,
+          ).strip()
+          with open(os.environ["GITHUB_OUTPUT"], "a", encoding="utf-8") as output_file:
+              print(f"matrix={matrix_json}", file=output_file)
+          PY
+
+    outputs:
+      matrix: ${{ steps.set-matrix.outputs.matrix }}
diff --git a/.github/workflows/slow-checks.yml b/.github/workflows/slow-checks.yml
index 8c4cd585f..5e127d1cd 100644
--- a/.github/workflows/slow-checks.yml
+++ b/.github/workflows/slow-checks.yml
@@ -6,12 +6,14 @@ on:
 jobs:
   build-matrix:
     name: Build Matrix
-    uses: ./.github/workflows/matrix-python.yml
+    uses: ./.github/workflows/matrix.yml
+    with:
+      matrix_keys_json: '["python_versions"]'
     permissions:
       contents: read
 
   run-integration-tests:
-    name: Run Integration Tests (Python-${{ matrix.python-version }})
+    name: Run Integration Tests (Python-${{ matrix.python_versions }})
     needs:
       - build-matrix
     runs-on: "ubuntu-24.04"
@@ -31,7 +33,7 @@ jobs:
         id: set-up-python-and-poetry-environment
         uses: exasol/python-toolbox/.github/actions/python-environment@v8
         with:
-          python-version: ${{ matrix.python-version }}
+          python-version: ${{ matrix.python_versions }}
           poetry-version: "2.3.0"
 
       - name: Run Integration Tests
@@ -42,7 +44,7 @@ jobs:
         id: upload-artifacts
         uses: actions/upload-artifact@v7
         with:
-          name: coverage-python${{ matrix.python-version }}-slow
+          name: coverage-python${{ matrix.python_versions }}-slow
           path: .coverage
           include-hidden-files: true
           overwrite: false
diff --git a/.github/workflows/test-python-environment.yml b/.github/workflows/test-python-environment.yml
index f05267e9a..10432180e 100644
--- a/.github/workflows/test-python-environment.yml
+++ b/.github/workflows/test-python-environment.yml
@@ -41,7 +41,9 @@ jobs:
     needs:
       - check-changes
     if: needs.check-changes.outputs.should_run == 'true'
-    uses: ./.github/workflows/matrix-all.yml
+    uses: ./.github/workflows/matrix.yml
+    with:
+      matrix_keys_json: '["python_versions"]'
     permissions:
       contents: read
 
@@ -60,8 +62,8 @@ jobs:
           - int-linux-x64-4core-gpu-t4-ubuntu24.04-1
           - int-linux-x64-4core-ubuntu24.04-1
           - int-linux-x64-2core-ubuntu24.04-1
-        python-version: ${{ fromJson(needs.build-matrix.outputs.matrix).python-version }}
-    name: Verify Poetry Setup for ${{ matrix.runner }} (Python-${{ matrix.python-version }})
+        python-versions: ${{ fromJson(needs.build-matrix.outputs.matrix).python_versions }}
+    name: Verify Poetry Setup for ${{ matrix.runner }} (Python-${{ matrix.python-versions }})
     runs-on:
       labels: ${{ matrix.runner }}
     steps:
@@ -75,7 +77,7 @@ jobs:
         id: set-up-python-and-poetry-environment
         uses: ./.github/actions/python-environment
         with:
-          python-version: "${{ matrix.python-version }}"
+          python-version: "${{ matrix.python-versions }}"
           poetry-version: "2.3.0"
 
       - name: Check Poetry Version
@@ -85,7 +87,7 @@ jobs:
       - name: Validate Python Version
         id: validate-python-version
         env:
-          PYTHON_VERSION: ${{ matrix.python-version }}
+          PYTHON_VERSION: ${{ matrix.python-versions }}
         run: |
           poetry run which python
           poetry run python --version
diff --git a/doc/user_guide/features/github_workflows/index.rst b/doc/user_guide/features/github_workflows/index.rst
index 0e699d9a8..0b550ec93 100644
--- a/doc/user_guide/features/github_workflows/index.rst
+++ b/doc/user_guide/features/github_workflows/index.rst
@@ -84,6 +84,10 @@ Maintained by the PTB
      - Workflow call
      - Calls Nox session ``matrix:all``, which typically evaluates ``exasol_versions``
        and ``python_versions`` from the ``PROJECT_CONFIG``.
+   * - ``matrix.yml``
+     - Workflow call
+     - Calls Nox session ``matrix:generate`` with one or more space-separated
+       ``BaseConfig`` keys to build a custom matrix from the ``PROJECT_CONFIG``.
    * - ``matrix-exasol.yml``
      - Workflow call
      - Calls Nox session ``matrix:exasol`` to get the ``exasol_versions`` from the
diff --git a/exasol/toolbox/nox/_ci.py b/exasol/toolbox/nox/_ci.py
index ff3f047dc..af9bfc6fe 100644
--- a/exasol/toolbox/nox/_ci.py
+++ b/exasol/toolbox/nox/_ci.py
@@ -1,5 +1,7 @@
+import argparse
 import json
-import logging
+from collections.abc import Iterable
+from typing import Any
 
 import nox
 from nox import Session
@@ -9,32 +11,121 @@
     PROJECT_CONFIG,
 )
 
-_log = logging.getLogger(__name__)
+# The relevant nox sessions will be removed in:
+#   https://github.com/exasol/python-toolbox/issues/859
+MATRIX_DEPRECATION_DATE = "2026-09-15"
 
 
-def _python_matrix(config: BaseConfig):
-    return {"python-version": config.python_versions}
+def _matrix_keys(config: BaseConfig) -> tuple[str, ...]:
+    """
+    Return the config keys that are valid for matrix generation.
 
+    Includes both declared fields and computed fields.
+    """
 
-def _exasol_matrix(config: BaseConfig):
-    return {"exasol-version": config.exasol_versions}
+    config_class = type(config)
+    return tuple(config_class.model_fields) + tuple(config_class.model_computed_fields)
+
+
+def _matrix_args(session: Session, config: BaseConfig) -> list[str]:
+    parser = argparse.ArgumentParser(
+        prog="nox -s matrix:generate",
+        usage="nox -s matrix:generate -- <config-key> [<config-key> ...]",
+        formatter_class=argparse.ArgumentDefaultsHelpFormatter,
+    )
+    parser.add_argument(
+        "keys",
+        nargs="+",
+        choices=sorted(_matrix_keys(config)),
+        help="BaseConfig keys to include in the generated matrix output",
+    )
+    return parser.parse_args(session.posargs).keys
+
+
+def _dump_matrix(config: BaseConfig, keys: Iterable[str]) -> dict[str, Any]:
+    """
+    Build a JSON-serializable matrix subset from the project's config.
+
+    GitHub Actions matrix values must be arrays. Pydantic already serializes
+    tuple-based config values to lists, so scalar values are wrapped in a
+    single-element list here.
+    """
+
+    allowed_keys = set(_matrix_keys(config))
+    requested_keys = tuple(keys)
+    for key in requested_keys:
+        if key not in allowed_keys:
+            raise KeyError(key)
+
+    matrix = config.model_dump(mode="json", include=set(requested_keys))
+    for key, value in matrix.items():
+        if not isinstance(value, list):
+            matrix[key] = [value]
+    return matrix
+
+
+def _print_deprecated_matrix(
+    session: Session,
+    config: BaseConfig,
+    key_map: dict[str, str],
+    session_name: str,
+    replacement_args: str,
+) -> None:
+    matrix = _dump_matrix(config, key_map.values())
+    renamed_matrix: dict[str, Any] = {}
+    for output_key, config_key in key_map.items():
+        renamed_matrix[output_key] = matrix[config_key]
+    print(json.dumps(renamed_matrix))
+
+    session.warn(
+        f"Warning: `nox -s {session_name}` is deprecated and will be removed on "
+        f"{MATRIX_DEPRECATION_DATE}. Use `nox -s matrix:generate -- {replacement_args}` "
+        "instead."
+    )
+
+
+@nox.session(name="matrix:generate", python=False)
+def generate_matrix(session: Session) -> None:
+    """Output selected BaseConfig values as JSON."""
+    keys = _matrix_args(session, PROJECT_CONFIG)
+    matrix = _dump_matrix(PROJECT_CONFIG, keys)
+    print(json.dumps(matrix))
 
 
 @nox.session(name="matrix:python", python=False)
 def python_matrix(session: Session) -> None:
     """Output the build matrix for Python versions as JSON."""
-    print(json.dumps(_python_matrix(PROJECT_CONFIG)))
+    _print_deprecated_matrix(
+        session=session,
+        config=PROJECT_CONFIG,
+        key_map={"python-version": "python_versions"},
+        session_name="matrix:python",
+        replacement_args="python_versions",
+    )
 
 
 @nox.session(name="matrix:exasol", python=False)
 def exasol_matrix(session: Session) -> None:
     """Output the build matrix for Exasol versions as JSON."""
-    print(json.dumps(_exasol_matrix(PROJECT_CONFIG)))
+    _print_deprecated_matrix(
+        session=session,
+        config=PROJECT_CONFIG,
+        key_map={"exasol-version": "exasol_versions"},
+        session_name="matrix:exasol",
+        replacement_args="exasol_versions",
+    )
 
 
 @nox.session(name="matrix:all", python=False)
 def full_matrix(session: Session) -> None:
     """Output the full build matrix for Python & Exasol versions as JSON."""
-    matrix = _python_matrix(PROJECT_CONFIG)
-    matrix.update(_exasol_matrix(PROJECT_CONFIG))
-    print(json.dumps(matrix))
+    _print_deprecated_matrix(
+        session=session,
+        config=PROJECT_CONFIG,
+        key_map={
+            "python-version": "python_versions",
+            "exasol-version": "exasol_versions",
+        },
+        session_name="matrix:all",
+        replacement_args="python_versions exasol_versions",
+    )
diff --git a/exasol/toolbox/nox/tasks.py b/exasol/toolbox/nox/tasks.py
index 0fe726fbf..434417020 100644
--- a/exasol/toolbox/nox/tasks.py
+++ b/exasol/toolbox/nox/tasks.py
@@ -66,6 +66,7 @@ def check(session: Session) -> None:
 )
 
 from exasol.toolbox.nox._ci import (
+    generate_matrix,
     python_matrix,
     exasol_matrix,
     full_matrix,
diff --git a/exasol/toolbox/templates/github/workflows/matrix-all.yml b/exasol/toolbox/templates/github/workflows/matrix-all.yml
deleted file mode 100644
index c24c2f2db..000000000
--- a/exasol/toolbox/templates/github/workflows/matrix-all.yml
+++ /dev/null
@@ -1,40 +0,0 @@
-(( workflow_header ))
-name: Build Matrix (All Versions)
-
-on:
-  workflow_call:
-    outputs:
-      matrix:
-        description: "Generates the all versions build matrix"
-        value: ${{ jobs.set-matrix-all.outputs.matrix }}
-
-jobs:
-  set-matrix-all:
-    runs-on: "(( os_version ))"
-    permissions:
-      contents: read
-    steps:
-      - name: Check out Repository
-        id: check-out-repository
-        uses: actions/checkout@v6
-        with:
-          persist-credentials: false
-
-      - name: Set up Python & Poetry Environment
-        id: set-up-python-and-poetry-environment
-        uses: exasol/python-toolbox/.github/actions/python-environment@v8
-        with:
-          python-version: "(( minimum_python_version ))"
-          poetry-version: "(( dependency_manager_version ))"
-
-      - name: Generate Matrix
-        id: generate-matrix
-        run: poetry run -- nox -s matrix:all
-
-      - name: Set Matrix
-        id: set-matrix
-        run: |
-          echo "matrix=$(poetry run -- nox -s matrix:all)" >> $GITHUB_OUTPUT
-
-    outputs:
-      matrix: ${{ steps.set-matrix.outputs.matrix }}
diff --git a/exasol/toolbox/templates/github/workflows/matrix-exasol.yml b/exasol/toolbox/templates/github/workflows/matrix-exasol.yml
deleted file mode 100644
index 18b3b851b..000000000
--- a/exasol/toolbox/templates/github/workflows/matrix-exasol.yml
+++ /dev/null
@@ -1,40 +0,0 @@
-(( workflow_header ))
-name: Build Matrix (Exasol)
-
-on:
-  workflow_call:
-    outputs:
-      matrix:
-        description: "Generates the exasol version build matrix"
-        value: ${{ jobs.set-matrix-exasol.outputs.matrix }}
-
-jobs:
-  set-matrix-exasol:
-    runs-on: "(( os_version ))"
-    permissions:
-      contents: read
-    steps:
-      - name: Check out Repository
-        id: check-out-repository
-        uses: actions/checkout@v6
-        with:
-          persist-credentials: false
-
-      - name: Set up Python & Poetry Environment
-        id: set-up-python-and-poetry-environment
-        uses: exasol/python-toolbox/.github/actions/python-environment@v8
-        with:
-          python-version: "(( minimum_python_version ))"
-          poetry-version: "(( dependency_manager_version ))"
-
-      - name: Generate Matrix
-        id: generate-matrix
-        run: poetry run -- nox -s matrix:exasol
-
-      - name: Set Matrix
-        id: set-matrix
-        run: |
-          echo "matrix=$(poetry run -- nox -s matrix:exasol)" >> $GITHUB_OUTPUT
-
-    outputs:
-      matrix: ${{ steps.set-matrix.outputs.matrix }}
diff --git a/exasol/toolbox/templates/github/workflows/matrix-python.yml b/exasol/toolbox/templates/github/workflows/matrix-python.yml
deleted file mode 100644
index 062426ff1..000000000
--- a/exasol/toolbox/templates/github/workflows/matrix-python.yml
+++ /dev/null
@@ -1,40 +0,0 @@
-(( workflow_header ))
-name: Build Matrix (Python)
-
-on:
-  workflow_call:
-    outputs:
-      matrix:
-        description: "Generates the python version build matrix"
-        value: ${{ jobs.set-matrix-python.outputs.matrix }}
-
-jobs:
-  set-matrix-python:
-    runs-on: "(( os_version ))"
-    permissions:
-      contents: read
-    steps:
-      - name: Check out Repository
-        id: check-out-repository
-        uses: actions/checkout@v6
-        with:
-          persist-credentials: false
-
-      - name: Set up Python & Poetry Environment
-        id: set-up-python-and-poetry-environment
-        uses: exasol/python-toolbox/.github/actions/python-environment@v8
-        with:
-          python-version: "(( minimum_python_version ))"
-          poetry-version: "(( dependency_manager_version ))"
-
-      - name: Generate Matrix
-        id: generate-matrix
-        run: poetry run -- nox -s matrix:python
-
-      - name: Set Matrix
-        id: set-matrix
-        run: |
-          echo "matrix=$(poetry run -- nox -s matrix:python)" >> $GITHUB_OUTPUT
-
-    outputs:
-      matrix: ${{ steps.set-matrix.outputs.matrix }}
diff --git a/exasol/toolbox/templates/github/workflows/matrix.yml b/exasol/toolbox/templates/github/workflows/matrix.yml
new file mode 100644
index 000000000..e4b6ec331
--- /dev/null
+++ b/exasol/toolbox/templates/github/workflows/matrix.yml
@@ -0,0 +1,78 @@
+(( workflow_header ))
+name: Build Matrix
+
+on:
+  workflow_call:
+    inputs:
+      matrix_keys_json:
+        description: "JSON array of BaseConfig keys to include in the generated matrix output."
+        required: true
+        type: string
+    outputs:
+      matrix:
+        description: "Generates the requested build matrix"
+        value: ${{ jobs.set-matrix.outputs.matrix }}
+
+jobs:
+  set-matrix:
+    runs-on: "(( os_version ))"
+    permissions:
+      contents: read
+    steps:
+      - name: Check out Repository
+        id: check-out-repository
+        uses: actions/checkout@v6
+        with:
+          persist-credentials: false
+
+      - name: Set up Python & Poetry Environment
+        id: set-up-python-and-poetry-environment
+        uses: exasol/python-toolbox/.github/actions/python-environment@v8
+        with:
+          python-version: "(( minimum_python_version ))"
+          poetry-version: "(( dependency_manager_version ))"
+
+      - name: Parse Matrix Keys
+        id: parse-matrix-keys
+        env:
+          MATRIX_KEYS_JSON: ${{ inputs.matrix_keys_json }}
+        run: |
+          python - <<'PY'
+          import json
+          import os
+
+          matrix_keys = json.loads(os.environ["MATRIX_KEYS_JSON"])
+          with open(os.environ["GITHUB_OUTPUT"], "a", encoding="utf-8") as output_file:
+              print(f"matrix_keys_json={json.dumps(matrix_keys)}", file=output_file)
+          PY
+
+      - name: Generate Matrix
+        id: set-matrix
+        env:
+          MATRIX_KEYS_JSON: ${{ steps.parse-matrix-keys.outputs.matrix_keys_json }}
+        run: |
+          python - <<'PY'
+          import json
+          import os
+          import subprocess
+
+          matrix_keys = json.loads(os.environ["MATRIX_KEYS_JSON"])
+          matrix_json = subprocess.check_output(
+              [
+                  "poetry",
+                  "run",
+                  "--",
+                  "nox",
+                  "-s",
+                  "matrix:generate",
+                  "--",
+                  *matrix_keys,
+              ],
+              text=True,
+          ).strip()
+          with open(os.environ["GITHUB_OUTPUT"], "a", encoding="utf-8") as output_file:
+              print(f"matrix={matrix_json}", file=output_file)
+          PY
+
+    outputs:
+      matrix: ${{ steps.set-matrix.outputs.matrix }}
diff --git a/exasol/toolbox/templates/github/workflows/slow-checks.yml b/exasol/toolbox/templates/github/workflows/slow-checks.yml
index 618e1790a..01b9a6c0c 100644
--- a/exasol/toolbox/templates/github/workflows/slow-checks.yml
+++ b/exasol/toolbox/templates/github/workflows/slow-checks.yml
@@ -8,12 +8,14 @@ on:
 jobs:
   build-matrix:
     name: Build Matrix
-    uses: ./.github/workflows/matrix-all.yml
+    uses: ./.github/workflows/matrix.yml
+    with:
+      matrix_keys_json: '["python_versions","exasol_versions"]'
     permissions:
       contents: read
 
   run-integration-tests:
-    name: Run Integration Tests (Python-${{ matrix.python-version }}, Exasol-${{ matrix.exasol-version}})
+    name: Run Integration Tests (Python-${{ matrix.python_versions }}, Exasol-${{ matrix.exasol_versions}})
     needs:
       - build-matrix
     runs-on: "(( os_version ))"
@@ -35,18 +37,18 @@ jobs:
         id: set-up-python-and-poetry-environment
         uses: exasol/python-toolbox/.github/actions/python-environment@v8
         with:
-          python-version: ${{ matrix.python-version }}
+          python-version: ${{ matrix.python_versions }}
           poetry-version: "(( dependency_manager_version ))"
 
       - name: Run Integration Tests
         id: run-integration-tests
-        run: poetry run -- nox -s test:integration -- --coverage --db-version ${{ matrix.exasol-version }}
+        run: poetry run -- nox -s test:integration -- --coverage --db-version ${{ matrix.exasol_versions }}
 
       - name: Upload Artifacts
         id: upload-artifacts
         uses: actions/upload-artifact@v7
         with:
-          name: coverage-python${{ matrix.python-version }}-exasol${{ matrix.exasol-version }}-slow
+          name: coverage-python${{ matrix.python_versions }}-exasol${{ matrix.exasol_versions }}-slow
           path: .coverage
           include-hidden-files: true
           overwrite: false
diff --git a/project-template/{{cookiecutter.repo_name}}/pyproject.toml b/project-template/{{cookiecutter.repo_name}}/pyproject.toml
index db6d6ca7d..cdf34b5ef 100644
--- a/project-template/{{cookiecutter.repo_name}}/pyproject.toml
+++ b/project-template/{{cookiecutter.repo_name}}/pyproject.toml
@@ -35,7 +35,7 @@ include = [
 [tool.poetry.requires-plugins]
 poetry-plugin-export = ">=1.8"
 
-[poetry.urls]
+[project.urls]
 repository = "https://github.com/exasol/{{cookiecutter.repo_name}}"
 homepage = "https://github.com/exasol/{{cookiecutter.repo_name}}"
 
diff --git a/pyproject.toml b/pyproject.toml
index c824c1faf..178c9b8b7 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -84,7 +84,7 @@ include = [
     "exasol/toolbox/templates/**/*"
 ]
 
-[poetry.urls]
+[project.urls]
 Homepage = "https://www.exasol.com/"
 Documentation = "https://exasol.github.io/python-toolbox/"
 Source = "https://github.com/exasol/python-toolbox"
diff --git a/test/integration/project-template/nox_test.py b/test/integration/project-template/nox_test.py
index e06fe9f62..994e998fa 100644
--- a/test/integration/project-template/nox_test.py
+++ b/test/integration/project-template/nox_test.py
@@ -83,4 +83,4 @@ def test_install_github_workflows(self, poetry_path, run_command):
         assert output.returncode == 0
 
         file_list = run_command(["ls", ".github/workflows"]).stdout.splitlines()
-        assert len(file_list) == 16
+        assert len(file_list) == 14
diff --git a/test/unit/nox/_ci_test.py b/test/unit/nox/_ci_test.py
new file mode 100644
index 000000000..7fc0adb08
--- /dev/null
+++ b/test/unit/nox/_ci_test.py
@@ -0,0 +1,141 @@
+from __future__ import annotations
+
+import json
+from unittest.mock import patch
+
+import pytest
+from pydantic import computed_field
+
+from exasol.toolbox.config import BaseConfig
+from exasol.toolbox.nox._ci import (
+    _dump_matrix,
+    exasol_matrix,
+    full_matrix,
+    generate_matrix,
+    python_matrix,
+)
+
+
+@pytest.fixture
+def nox_session_runner_posargs(request) -> list[str]:
+    return list(getattr(request, "param", []))
+
+
+@pytest.fixture
+def config(tmp_path) -> BaseConfig:
+    class Config(BaseConfig):
+        extra_matrix_value: str = "extra"
+
+        @computed_field  # type: ignore[misc]
+        @property
+        def computed_matrix_value(self) -> str:
+            return f"{self.project_name}-computed"
+
+    return Config(root_path=tmp_path, project_name="toolbox")
+
+
+class TestGenerateMatrix:
+    @staticmethod
+    @pytest.mark.parametrize(
+        "nox_session_runner_posargs",
+        [["computed_matrix_value", "extra_matrix_value"]],
+        indirect=True,
+    )
+    def test_uses_requested_field_names(
+        nox_session,
+        config,
+        capsys,
+        nox_session_runner_posargs,
+    ):
+        with patch("exasol.toolbox.nox._ci.PROJECT_CONFIG", new=config):
+            generate_matrix(nox_session)
+
+        assert json.loads(capsys.readouterr().out) == {
+            "computed_matrix_value": ["toolbox-computed"],
+            "extra_matrix_value": ["extra"],
+        }
+
+    @staticmethod
+    @pytest.mark.parametrize(
+        "nox_session_runner_posargs",
+        [["missing_value"]],
+        indirect=True,
+    )
+    def test_rejects_unknown_field(
+        nox_session,
+        config,
+        capsys,
+        nox_session_runner_posargs,
+    ):
+        with patch("exasol.toolbox.nox._ci.PROJECT_CONFIG", new=config):
+            with pytest.raises(SystemExit):
+                generate_matrix(nox_session)
+
+        assert "invalid choice: 'missing_value'" in capsys.readouterr().err
+
+
+class TestDumpMatrix:
+    @staticmethod
+    @pytest.mark.parametrize(
+        ("requested_keys", "expected"),
+        [
+            (
+                ("computed_matrix_value",),
+                {"computed_matrix_value": ["toolbox-computed"]},
+            ),
+            (
+                ("computed_matrix_value", "extra_matrix_value"),
+                {
+                    "computed_matrix_value": ["toolbox-computed"],
+                    "extra_matrix_value": ["extra"],
+                },
+            ),
+        ],
+    )
+    def test_returns_requested_keys(config, requested_keys, expected):
+        assert _dump_matrix(config, requested_keys) == expected
+
+    @staticmethod
+    def test_rejects_unknown_key(config):
+        with pytest.raises(KeyError, match="missing_matrix_value"):
+            _dump_matrix(config, ("missing_matrix_value",))
+
+
+class TestDeprecatedMatrixSessions:
+    @staticmethod
+    def test_exasol_session_still_emits_field_names(
+        nox_session, config, caplog, capsys
+    ):
+        with patch("exasol.toolbox.nox._ci.PROJECT_CONFIG", new=config):
+            exasol_matrix(nox_session)
+
+        captured = capsys.readouterr()
+        assert json.loads(captured.out) == {
+            "exasol-version": ["7.1.30", "8.29.13", "2025.1.8"]
+        }
+        assert len(caplog.messages) == 1
+
+    @staticmethod
+    def test_python_session_still_emits_field_names(
+        nox_session, config, caplog, capsys
+    ):
+        with patch("exasol.toolbox.nox._ci.PROJECT_CONFIG", new=config):
+            python_matrix(nox_session)
+
+        captured = capsys.readouterr()
+        assert json.loads(captured.out) == {
+            "python-version": ["3.10", "3.11", "3.12", "3.13", "3.14"]
+        }
+        assert len(caplog.messages) == 1
+
+    @staticmethod
+    def test_full_session_still_emits_field_names(nox_session, config, caplog, capsys):
+        with patch("exasol.toolbox.nox._ci.PROJECT_CONFIG", new=config):
+            full_matrix(nox_session)
+
+        captured = capsys.readouterr()
+        assert json.loads(captured.out) == {
+            "python-version": ["3.10", "3.11", "3.12", "3.13", "3.14"],
+            "exasol-version": ["7.1.30", "8.29.13", "2025.1.8"],
+        }
+        assert len(caplog.messages) == 1
diff --git a/test/unit/nox/_workflow_test.py b/test/unit/nox/_workflow_test.py
index 983d16256..55ec74c10 100644
--- a/test/unit/nox/_workflow_test.py
+++ b/test/unit/nox/_workflow_test.py
@@ -39,7 +39,7 @@ class TestGenerateWorkflow:
     @staticmethod
     @pytest.mark.parametrize(
         "nox_session_runner_posargs, expected_count",
-        [(ALL, 16), *[(key, 1) for key in WORKFLOW_TEMPLATE_OPTIONS.keys()]],
+        [(ALL, 14), *[(key, 1) for key in WORKFLOW_TEMPLATE_OPTIONS.keys()]],
         indirect=["nox_session_runner_posargs"],
     )
     def test_works_as_expected(
@@ -128,7 +128,7 @@ def test_raises_session_quit_when_workflows_are_out_of_date(
                 check_workflow(nox_session)
 
         assert str(exc.value) == (
-            "\n16 workflows are out of date:\n"
+            "\n14 workflows are out of date:\n"
             "- build-and-publish\n"
             "- cd\n"
             "- check-release-tag\n"
@@ -137,9 +137,7 @@ def test_raises_session_quit_when_workflows_are_out_of_date(
             "- dependency-update\n"
             "- fast-tests\n"
             "- gh-pages\n"
-            "- matrix-all\n"
-            "- matrix-exasol\n"
-            "- matrix-python\n"
+            "- matrix\n"
             "- merge-gate\n"
             "- periodic-validation\n"
             "- pr-merge\n"
diff --git a/test/unit/util/workflows/templates_test.py b/test/unit/util/workflows/templates_test.py
index 32a62957a..8969ad658 100644
--- a/test/unit/util/workflows/templates_test.py
+++ b/test/unit/util/workflows/templates_test.py
@@ -25,9 +25,7 @@ def test_get_workflow_templates(project_config):
         "fast-tests",
         "dependency-update",
         "gh-pages",
-        "matrix-all",
-        "matrix-exasol",
-        "matrix-python",
+        "matrix",
         "merge-gate",
         "periodic-validation",
         "pr-merge",