From 23d5ec9ce0061f2368c1574bf02a8af4722d870f Mon Sep 17 00:00:00 2001
From: Ariel Schulz <ariel.schulz@exasol.com>
Date: Thu, 12 Feb 2026 10:33:52 +0100
Subject: [PATCH 01/10] Adjust so that noxconfig.py can be loaded here until
 the migration is done

---
 .import_linter_config | 1 +
 1 file changed, 1 insertion(+)

diff --git a/.import_linter_config b/.import_linter_config
index 01a924fd8..78f051f90 100644
--- a/.import_linter_config
+++ b/.import_linter_config
@@ -28,3 +28,4 @@ ignore_imports =
     # in each CLI usage), we allow the noxconfig to be imported within these modules.
     exasol.toolbox.nox.* -> noxconfig
     exasol.toolbox.tools.template -> noxconfig
+    exasol.toolbox.util.workflow.* -> noxconfig

From 60b4a832605ad447b7abdb24a6791a0e7c5ae826 Mon Sep 17 00:00:00 2001
From: Ariel Schulz <ariel.schulz@exasol.com>
Date: Thu, 12 Feb 2026 10:55:32 +0100
Subject: [PATCH 02/10] Add custom exception for
 InvalidWorkflowPatcherYamlError

---
 exasol/toolbox/util/workflows/patch_workflow.py | 15 +++++++++++++--
 test/unit/util/workflows/patch_workflow_test.py |  9 ++++++++-
 2 files changed, 21 insertions(+), 3 deletions(-)

diff --git a/exasol/toolbox/util/workflows/patch_workflow.py b/exasol/toolbox/util/workflows/patch_workflow.py
index 9b48fac6e..1527a2caf 100644
--- a/exasol/toolbox/util/workflows/patch_workflow.py
+++ b/exasol/toolbox/util/workflows/patch_workflow.py
@@ -6,12 +6,20 @@
     BaseModel,
     ConfigDict,
     Field,
+    ValidationError,
 )
 from ruamel.yaml import CommentedMap
 
 from exasol.toolbox.util.workflows.render_yaml import YamlRenderer
 
 
+class InvalidWorkflowPatcherYamlError(Exception):
+    def __init__(self, file_path: Path):
+        super().__init__(
+            f"File '{file_path}' is malformed; it failed Pydantic validation."
+        )
+
+
 class ActionType(str, Enum):
     INSERT_AFTER = "INSERT_AFTER"
     REPLACE = "REPLACE"
@@ -92,5 +100,8 @@ class WorkflowPatcher(YamlRenderer):
 
     def get_yaml_dict(self, file_path: Path) -> CommentedMap:
         loaded_yaml = super().get_yaml_dict(file_path)
-        WorkflowPatcherConfig.model_validate(loaded_yaml)
-        return loaded_yaml
+        try:
+            WorkflowPatcherConfig.model_validate(loaded_yaml)
+            return loaded_yaml
+        except ValidationError as exc:
+            raise InvalidWorkflowPatcherYamlError(file_path=file_path) from exc
diff --git a/test/unit/util/workflows/patch_workflow_test.py b/test/unit/util/workflows/patch_workflow_test.py
index dc6d98151..e95bf0974 100644
--- a/test/unit/util/workflows/patch_workflow_test.py
+++ b/test/unit/util/workflows/patch_workflow_test.py
@@ -7,6 +7,7 @@
 
 from exasol.toolbox.util.workflows.patch_workflow import (
     ActionType,
+    InvalidWorkflowPatcherYamlError,
     WorkflowPatcher,
 )
 from noxconfig import PROJECT_CONFIG
@@ -86,5 +87,11 @@ def test_raises_error_for_unknown_action(workflow_patcher_yaml, workflow_patcher
         content = cleandoc(ExampleYaml.step_customization.format(action="UNKNOWN"))
         workflow_patcher_yaml.write_text(content)
 
-        with pytest.raises(ValidationError, match="Input should be"):
+        with pytest.raises(
+            InvalidWorkflowPatcherYamlError,
+            match="is malformed; it failed Pydantic validation",
+        ) as exc:
             workflow_patcher.get_yaml_dict(workflow_patcher_yaml)
+
+        underlying_error = exc.value.__cause__
+        assert isinstance(underlying_error, ValidationError)

From 33c8f57c55a5132649310e3f9ca98ea8d34adebc Mon Sep 17 00:00:00 2001
From: Ariel Schulz <ariel.schulz@exasol.com>
Date: Thu, 12 Feb 2026 11:24:19 +0100
Subject: [PATCH 03/10] Add custom exceptions YamlSyntaxError and
 TemplateRenderingError

---
 exasol/toolbox/util/workflows/render_yaml.py | 45 +++++++--
 exasol/toolbox/util/workflows/workflow.py    | 11 +--
 test/unit/util/workflows/render_yaml_test.py | 98 ++++++++++++++------
 test/unit/util/workflows/workflow_test.py    | 15 ---
 4 files changed, 113 insertions(+), 56 deletions(-)

diff --git a/exasol/toolbox/util/workflows/render_yaml.py b/exasol/toolbox/util/workflows/render_yaml.py
index 23b57dd57..7650f58ff 100644
--- a/exasol/toolbox/util/workflows/render_yaml.py
+++ b/exasol/toolbox/util/workflows/render_yaml.py
@@ -4,17 +4,46 @@
 from pathlib import Path
 from typing import Any
 
-from jinja2 import Environment
+from jinja2 import (
+    Environment,
+    StrictUndefined,
+    TemplateError,
+)
 from ruamel.yaml import (
     YAML,
     CommentedMap,
 )
+from ruamel.yaml.error import YAMLError
 
 jinja_env = Environment(
-    variable_start_string="((", variable_end_string="))", autoescape=True
+    variable_start_string="((",
+    variable_end_string="))",
+    autoescape=True,
+    # This requires that all Jinja variables must be defined in the provided
+    # dictionary. If not, then a `jinja2.exceptions.UndefinedError` exception
+    # will be raised.
+    undefined=StrictUndefined,
 )
 
 
+class YamlSyntaxError(Exception):
+    """Raised when the rendered template is not a valid YAML document."""
+
+    def __init__(self, file_path: Path):
+        super().__init__(
+            f"File '{file_path}' could not be parsed by ruamel-yaml. Check for invalid YAML syntax."
+        )
+
+
+class TemplateRenderingError(Exception):
+    """Raised when Jinja2 fails to process the template."""
+
+    def __init__(self, file_path: Path):
+        super().__init__(
+            f"File '{file_path}' failed to render. Check Jinja2-related errors."
+        )
+
+
 @dataclass(frozen=True)
 class YamlRenderer:
     """
@@ -53,10 +82,14 @@ def get_yaml_dict(self, file_path: Path) -> CommentedMap:
         with file_path.open("r", encoding="utf-8") as stream:
             raw_content = stream.read()
 
-        workflow_string = self._render_with_jinja(raw_content)
-
-        yaml = self._get_standard_yaml()
-        return yaml.load(workflow_string)
+        try:
+            workflow_string = self._render_with_jinja(raw_content)
+            yaml = self._get_standard_yaml()
+            return yaml.load(workflow_string)
+        except TemplateError as exc:
+            raise TemplateRenderingError(file_path=file_path) from exc
+        except YAMLError as exc:
+            raise YamlSyntaxError(file_path=file_path) from exc
 
     def get_as_string(self, yaml_dict: CommentedMap) -> str:
         """
diff --git a/exasol/toolbox/util/workflows/workflow.py b/exasol/toolbox/util/workflows/workflow.py
index fc54b653d..4bd02b19b 100644
--- a/exasol/toolbox/util/workflows/workflow.py
+++ b/exasol/toolbox/util/workflows/workflow.py
@@ -19,11 +19,6 @@ def load_from_template(cls, file_path: Path, github_template_dict: dict[str, Any
         if not file_path.exists():
             raise FileNotFoundError(file_path)
 
-        try:
-            workflow_renderer = WorkflowRenderer(
-                github_template_dict=github_template_dict
-            )
-            workflow = workflow_renderer.render(file_path=file_path)
-            return cls(content=workflow)
-        except Exception as e:
-            raise ValueError(f"Error rendering file: {file_path}") from e
+        workflow_renderer = WorkflowRenderer(github_template_dict=github_template_dict)
+        workflow = workflow_renderer.render(file_path=file_path)
+        return cls(content=workflow)
diff --git a/test/unit/util/workflows/render_yaml_test.py b/test/unit/util/workflows/render_yaml_test.py
index 035b7fd1c..cd8f33a34 100644
--- a/test/unit/util/workflows/render_yaml_test.py
+++ b/test/unit/util/workflows/render_yaml_test.py
@@ -1,8 +1,15 @@
 from inspect import cleandoc
 
 import pytest
-
-from exasol.toolbox.util.workflows.render_yaml import YamlRenderer
+from jinja2 import (
+    TemplateSyntaxError,
+    UndefinedError,
+)
+
+from exasol.toolbox.util.workflows.render_yaml import (
+    TemplateRenderingError,
+    YamlRenderer,
+)
 from noxconfig import PROJECT_CONFIG
 
 
@@ -11,9 +18,14 @@ def yaml_renderer() -> YamlRenderer:
     return YamlRenderer(github_template_dict=PROJECT_CONFIG.github_template_dict)
 
 
-class TestTemplateRenderer:
+@pytest.fixture
+def dummy_yaml(tmp_path):
+    return tmp_path / "dummy.yml"
+
+
+class TestYamlRenderer:
     @staticmethod
-    def test_works_for_general_case(tmp_path, yaml_renderer):
+    def test_works_for_general_case(dummy_yaml, yaml_renderer):
         input_yaml = """
         name: Build & Publish
 
@@ -29,15 +41,14 @@ def test_works_for_general_case(tmp_path, yaml_renderer):
             permissions:
               contents: write
         """
-        file_path = tmp_path / "dummy.yml"
         content = cleandoc(input_yaml)
-        file_path.write_text(content)
+        dummy_yaml.write_text(content)
 
-        yaml_dict = yaml_renderer.get_yaml_dict(file_path)
+        yaml_dict = yaml_renderer.get_yaml_dict(dummy_yaml)
         assert yaml_renderer.get_as_string(yaml_dict) == cleandoc(input_yaml)
 
     @staticmethod
-    def test_fixes_extra_horizontal_whitespace(tmp_path, yaml_renderer):
+    def test_fixes_extra_horizontal_whitespace(dummy_yaml, yaml_renderer):
         # required has 2 extra spaces
         input_yaml = """
         name: Build & Publish
@@ -59,15 +70,14 @@ def test_fixes_extra_horizontal_whitespace(tmp_path, yaml_renderer):
                 required: true
         """
 
-        file_path = tmp_path / "dummy.yml"
         content = cleandoc(input_yaml)
-        file_path.write_text(content)
+        dummy_yaml.write_text(content)
 
-        yaml_dict = yaml_renderer.get_yaml_dict(file_path)
+        yaml_dict = yaml_renderer.get_yaml_dict(dummy_yaml)
         assert yaml_renderer.get_as_string(yaml_dict) == cleandoc(expected_yaml)
 
     @staticmethod
-    def test_keeps_comments(tmp_path, yaml_renderer):
+    def test_keeps_comments(dummy_yaml, yaml_renderer):
         input_yaml = """
         steps:
           # Comment in nested area
@@ -84,15 +94,14 @@ def test_keeps_comments(tmp_path, yaml_renderer):
           # Comment in step
         """
 
-        file_path = tmp_path / "dummy.yml"
         content = cleandoc(input_yaml)
-        file_path.write_text(content)
+        dummy_yaml.write_text(content)
 
-        yaml_dict = yaml_renderer.get_yaml_dict(file_path)
+        yaml_dict = yaml_renderer.get_yaml_dict(dummy_yaml)
         assert yaml_renderer.get_as_string(yaml_dict) == cleandoc(expected_yaml)
 
     @staticmethod
-    def test_keeps_quotes_for_variables_as_is(tmp_path, yaml_renderer):
+    def test_keeps_quotes_for_variables_as_is(dummy_yaml, yaml_renderer):
         input_yaml = """
         - name: Build Artifacts
           run: poetry build
@@ -129,15 +138,14 @@ def test_keeps_quotes_for_variables_as_is(tmp_path, yaml_renderer):
             dist/*
         """
 
-        file_path = tmp_path / "dummy.yml"
         content = cleandoc(input_yaml)
-        file_path.write_text(content)
+        dummy_yaml.write_text(content)
 
-        yaml_dict = yaml_renderer.get_yaml_dict(file_path)
+        yaml_dict = yaml_renderer.get_yaml_dict(dummy_yaml)
         assert yaml_renderer.get_as_string(yaml_dict) == cleandoc(expected_yaml)
 
     @staticmethod
-    def test_updates_jinja_variables(tmp_path, yaml_renderer):
+    def test_updates_jinja_variables(dummy_yaml, yaml_renderer):
         input_yaml = """
         - name: Setup Python & Poetry Environment
           uses: exasol/python-toolbox/.github/actions/python-environment@v5
@@ -153,15 +161,14 @@ def test_updates_jinja_variables(tmp_path, yaml_renderer):
           poetry-version: "2.3.0"
         """
 
-        file_path = tmp_path / "dummy.yml"
         content = cleandoc(input_yaml)
-        file_path.write_text(content)
+        dummy_yaml.write_text(content)
 
-        yaml_dict = yaml_renderer.get_yaml_dict(file_path)
+        yaml_dict = yaml_renderer.get_yaml_dict(dummy_yaml)
         assert yaml_renderer.get_as_string(yaml_dict) == cleandoc(expected_yaml)
 
     @staticmethod
-    def test_preserves_list_format(tmp_path, yaml_renderer):
+    def test_preserves_list_format(dummy_yaml, yaml_renderer):
         input_yaml = """
         on:
           pull_request:
@@ -178,9 +185,46 @@ def test_preserves_list_format(tmp_path, yaml_renderer):
               python-versions: ["3.10", "3.11", "3.12", "3.13", "3.14"]
         """
 
-        file_path = tmp_path / "dummy.yml"
         content = cleandoc(input_yaml)
-        file_path.write_text(content)
+        dummy_yaml.write_text(content)
 
-        yaml_dict = yaml_renderer.get_yaml_dict(file_path)
+        yaml_dict = yaml_renderer.get_yaml_dict(dummy_yaml)
         assert yaml_renderer.get_as_string(yaml_dict) == cleandoc(input_yaml)
+
+    @staticmethod
+    def test_jinja_variable_unknown(dummy_yaml, yaml_renderer):
+        input_yaml = """
+        - name: Setup Python & Poetry Environment
+          uses: exasol/python-toolbox/.github/actions/python-environment@v5
+          with:
+            poetry-version: "(( bad_jinja ))"
+        """
+
+        content = cleandoc(input_yaml)
+        dummy_yaml.write_text(content)
+
+        with pytest.raises(
+            TemplateRenderingError, match="Check Jinja2-related errors."
+        ) as exc:
+            yaml_renderer.get_yaml_dict(dummy_yaml)
+        assert isinstance(exc.value.__cause__, UndefinedError)
+        assert "'bad_jinja' is undefined" in str(exc.value.__cause__)
+
+    @staticmethod
+    def test_jinja_variable_unclosed(dummy_yaml, yaml_renderer):
+        input_yaml = """
+        - name: Setup Python & Poetry Environment
+          uses: exasol/python-toolbox/.github/actions/python-environment@v5
+          with:
+            python-version: "(( minimum_python_version )"
+        """
+
+        content = cleandoc(input_yaml)
+        dummy_yaml.write_text(content)
+
+        with pytest.raises(
+            TemplateRenderingError, match="Check Jinja2-related errors."
+        ) as exc:
+            yaml_renderer.get_yaml_dict(dummy_yaml)
+        assert isinstance(exc.value.__cause__, TemplateSyntaxError)
+        assert "unexpected ')'" in str(exc.value.__cause__)
diff --git a/test/unit/util/workflows/workflow_test.py b/test/unit/util/workflows/workflow_test.py
index dafb0665e..69781b0a3 100644
--- a/test/unit/util/workflows/workflow_test.py
+++ b/test/unit/util/workflows/workflow_test.py
@@ -1,5 +1,4 @@
 import pytest
-from ruamel.yaml.parser import ParserError
 
 from exasol.toolbox.util.workflows.workflow import Workflow
 from noxconfig import PROJECT_CONFIG
@@ -42,17 +41,3 @@ def test_fails_when_yaml_does_not_exist(tmp_path):
                 file_path=file_path,
                 github_template_dict=PROJECT_CONFIG.github_template_dict,
             )
-
-    @staticmethod
-    def test_fails_when_yaml_malformed(tmp_path):
-        file_path = tmp_path / "test.yaml"
-        file_path.write_text(BAD_TEMPLATE)
-
-        with pytest.raises(ValueError, match="Error rendering file") as excinfo:
-            Workflow.load_from_template(
-                file_path=file_path,
-                github_template_dict=PROJECT_CONFIG.github_template_dict,
-            )
-
-        assert isinstance(excinfo.value.__cause__, ParserError)
-        assert "while parsing a block collection" in str(excinfo.value.__cause__)

From 14ed14b6700ef8f14d735628e83335e0c2509ab5 Mon Sep 17 00:00:00 2001
From: Ariel Schulz <ariel.schulz@exasol.com>
Date: Thu, 12 Feb 2026 11:48:38 +0100
Subject: [PATCH 04/10] Move example to conftest for re-use

---
 test/unit/util/workflows/conftest.py          | 32 ++++++++++++
 .../util/workflows/patch_workflow_test.py     | 51 +++++++------------
 2 files changed, 50 insertions(+), 33 deletions(-)
 create mode 100644 test/unit/util/workflows/conftest.py

diff --git a/test/unit/util/workflows/conftest.py b/test/unit/util/workflows/conftest.py
new file mode 100644
index 000000000..730e6caa6
--- /dev/null
+++ b/test/unit/util/workflows/conftest.py
@@ -0,0 +1,32 @@
+from dataclasses import dataclass
+
+import pytest
+
+
+@dataclass(frozen=True)
+class ExamplePatcherYaml:
+    remove_jobs = """
+        workflows:
+        - name: "checks.yml"
+          remove_jobs:
+            - build-documentation-and-check-links
+        """
+    step_customization = """
+        workflows:
+        - name: "checks.yml"
+          step_customizations:
+            - action: {action}
+              job: run-unit-tests
+              step_id: check-out-repository
+              content:
+                - name: SCM Checkout
+                  id: checkout-repo
+                  uses: actions/checkout@v6
+                  with:
+                    fetch-depth: 0
+        """
+
+
+@pytest.fixture(scope="session")
+def example_patcher_yaml():
+    return ExamplePatcherYaml
diff --git a/test/unit/util/workflows/patch_workflow_test.py b/test/unit/util/workflows/patch_workflow_test.py
index e95bf0974..fdcc5ec12 100644
--- a/test/unit/util/workflows/patch_workflow_test.py
+++ b/test/unit/util/workflows/patch_workflow_test.py
@@ -1,4 +1,3 @@
-from dataclasses import dataclass
 from inspect import cleandoc
 from pathlib import Path
 
@@ -13,30 +12,6 @@
 from noxconfig import PROJECT_CONFIG
 
 
-@dataclass(frozen=True)
-class ExampleYaml:
-    remove_jobs = """
-        workflows:
-        - name: "checks.yml"
-          remove_jobs:
-            - documentation
-        """
-    step_customization = """
-        workflows:
-        - name: "checks.yml"
-          step_customizations:
-            - action: {action}
-              job: Tests
-              step_id: checkout-repo
-              content:
-                - name: SCM Checkout
-                  id: checkout-repo
-                  uses: actions/checkout@v6
-                  with:
-                    fetch-depth: 0
-        """
-
-
 @pytest.fixture
 def workflow_patcher() -> WorkflowPatcher:
     return WorkflowPatcher(github_template_dict=PROJECT_CONFIG.github_template_dict)
@@ -49,8 +24,8 @@ def workflow_patcher_yaml(tmp_path: Path) -> Path:
 
 class TestWorkflowPatcher:
     @staticmethod
-    def test_remove_jobs(workflow_patcher_yaml, workflow_patcher):
-        content = cleandoc(ExampleYaml.remove_jobs)
+    def test_remove_jobs(example_patcher_yaml, workflow_patcher_yaml, workflow_patcher):
+        content = cleandoc(example_patcher_yaml.remove_jobs)
         workflow_patcher_yaml.write_text(content)
 
         yaml_dict = workflow_patcher.get_yaml_dict(workflow_patcher_yaml)
@@ -59,8 +34,12 @@ def test_remove_jobs(workflow_patcher_yaml, workflow_patcher):
 
     @staticmethod
     @pytest.mark.parametrize("action", ActionType)
-    def test_step_customizations(workflow_patcher_yaml, action, workflow_patcher):
-        content = cleandoc(ExampleYaml.step_customization.format(action=action.value))
+    def test_step_customizations(
+        example_patcher_yaml, workflow_patcher_yaml, action, workflow_patcher
+    ):
+        content = cleandoc(
+            example_patcher_yaml.step_customization.format(action=action.value)
+        )
         workflow_patcher_yaml.write_text(content)
 
         yaml_dict = workflow_patcher.get_yaml_dict(workflow_patcher_yaml)
@@ -70,9 +49,11 @@ def test_step_customizations(workflow_patcher_yaml, action, workflow_patcher):
 
 class TestStepCustomization:
     @staticmethod
-    def test_allows_extra_field(workflow_patcher_yaml, workflow_patcher):
+    def test_allows_extra_field(
+        example_patcher_yaml, workflow_patcher_yaml, workflow_patcher
+    ):
         content = f"""
-        {ExampleYaml.step_customization.format(action="REPLACE")}
+        {example_patcher_yaml.step_customization.format(action="REPLACE")}
                   extra-field: "test"
         """
         content = cleandoc(content)
@@ -83,8 +64,12 @@ def test_allows_extra_field(workflow_patcher_yaml, workflow_patcher):
         assert workflow_patcher.get_as_string(yaml_dict) == content
 
     @staticmethod
-    def test_raises_error_for_unknown_action(workflow_patcher_yaml, workflow_patcher):
-        content = cleandoc(ExampleYaml.step_customization.format(action="UNKNOWN"))
+    def test_raises_error_for_unknown_action(
+        example_patcher_yaml, workflow_patcher_yaml, workflow_patcher
+    ):
+        content = cleandoc(
+            example_patcher_yaml.step_customization.format(action="UNKNOWN")
+        )
         workflow_patcher_yaml.write_text(content)
 
         with pytest.raises(

From 92a08b93c91373c698eb9392e7be7b2b1a4b3214 Mon Sep 17 00:00:00 2001
From: Ariel Schulz <ariel.schulz@exasol.com>
Date: Thu, 12 Feb 2026 13:23:35 +0100
Subject: [PATCH 05/10] Switch to cached value

---
 .../toolbox/util/workflows/patch_workflow.py  | 18 +++++++++++++++---
 .../util/workflows/patch_workflow_test.py     | 19 ++++++++++---------
 2 files changed, 25 insertions(+), 12 deletions(-)

diff --git a/exasol/toolbox/util/workflows/patch_workflow.py b/exasol/toolbox/util/workflows/patch_workflow.py
index 1527a2caf..118b0c886 100644
--- a/exasol/toolbox/util/workflows/patch_workflow.py
+++ b/exasol/toolbox/util/workflows/patch_workflow.py
@@ -1,4 +1,8 @@
+from __future__ import annotations
+
+from dataclasses import dataclass
 from enum import Enum
+from functools import cached_property
 from pathlib import Path
 from typing import Any
 
@@ -90,6 +94,7 @@ class WorkflowPatcherConfig(BaseModel):
     workflows: list[Workflow]
 
 
+@dataclass(frozen=True)
 class WorkflowPatcher(YamlRenderer):
     """
     The :class:`WorkflowPatcher` enables users to define a YAML file
@@ -98,10 +103,17 @@ class WorkflowPatcher(YamlRenderer):
     The provided YAML file must meet the conditions of :class:`WorkflowPatcherConfig`.
     """
 
-    def get_yaml_dict(self, file_path: Path) -> CommentedMap:
-        loaded_yaml = super().get_yaml_dict(file_path)
+    file_path: Path
+
+    @cached_property
+    def content(self) -> CommentedMap:
+        """
+        The loaded YAML content. It loads on first access and
+        stays cached even though the class is frozen.
+        """
+        loaded_yaml = self.get_yaml_dict(self.file_path)
         try:
             WorkflowPatcherConfig.model_validate(loaded_yaml)
             return loaded_yaml
         except ValidationError as exc:
-            raise InvalidWorkflowPatcherYamlError(file_path=file_path) from exc
+            raise InvalidWorkflowPatcherYamlError(file_path=self.file_path) from exc
diff --git a/test/unit/util/workflows/patch_workflow_test.py b/test/unit/util/workflows/patch_workflow_test.py
index fdcc5ec12..401bdf505 100644
--- a/test/unit/util/workflows/patch_workflow_test.py
+++ b/test/unit/util/workflows/patch_workflow_test.py
@@ -13,8 +13,11 @@
 
 
 @pytest.fixture
-def workflow_patcher() -> WorkflowPatcher:
-    return WorkflowPatcher(github_template_dict=PROJECT_CONFIG.github_template_dict)
+def workflow_patcher(workflow_patcher_yaml) -> WorkflowPatcher:
+    return WorkflowPatcher(
+        github_template_dict=PROJECT_CONFIG.github_template_dict,
+        file_path=workflow_patcher_yaml,
+    )
 
 
 @pytest.fixture
@@ -28,9 +31,8 @@ def test_remove_jobs(example_patcher_yaml, workflow_patcher_yaml, workflow_patch
         content = cleandoc(example_patcher_yaml.remove_jobs)
         workflow_patcher_yaml.write_text(content)
 
-        yaml_dict = workflow_patcher.get_yaml_dict(workflow_patcher_yaml)
-
-        assert workflow_patcher.get_as_string(yaml_dict) == content
+        result = workflow_patcher.content
+        assert workflow_patcher.get_as_string(result) == content
 
     @staticmethod
     @pytest.mark.parametrize("action", ActionType)
@@ -42,9 +44,8 @@ def test_step_customizations(
         )
         workflow_patcher_yaml.write_text(content)
 
-        yaml_dict = workflow_patcher.get_yaml_dict(workflow_patcher_yaml)
-
-        assert workflow_patcher.get_as_string(yaml_dict) == content
+        result = workflow_patcher.content
+        assert workflow_patcher.get_as_string(result) == content
 
 
 class TestStepCustomization:
@@ -76,7 +77,7 @@ def test_raises_error_for_unknown_action(
             InvalidWorkflowPatcherYamlError,
             match="is malformed; it failed Pydantic validation",
         ) as exc:
-            workflow_patcher.get_yaml_dict(workflow_patcher_yaml)
+            workflow_patcher.content
 
         underlying_error = exc.value.__cause__
         assert isinstance(underlying_error, ValidationError)

From 40397cab356fbe79f22cdf08a02ea121c27a5412 Mon Sep 17 00:00:00 2001
From: Ariel Schulz <ariel.schulz@exasol.com>
Date: Fri, 13 Feb 2026 09:10:24 +0100
Subject: [PATCH 06/10] Make file_path part of class for improved exceptions

---
 .../toolbox/util/workflows/patch_workflow.py  |  4 +--
 .../util/workflows/process_template.py        |  6 ++---
 exasol/toolbox/util/workflows/render_yaml.py  |  9 ++++---
 exasol/toolbox/util/workflows/workflow.py     |  7 ++---
 .../util/workflows/patch_workflow_test.py     |  2 +-
 test/unit/util/workflows/render_yaml_test.py  | 26 ++++++++++---------
 6 files changed, 27 insertions(+), 27 deletions(-)

diff --git a/exasol/toolbox/util/workflows/patch_workflow.py b/exasol/toolbox/util/workflows/patch_workflow.py
index 118b0c886..2e2657d7d 100644
--- a/exasol/toolbox/util/workflows/patch_workflow.py
+++ b/exasol/toolbox/util/workflows/patch_workflow.py
@@ -103,15 +103,13 @@ class WorkflowPatcher(YamlRenderer):
     The provided YAML file must meet the conditions of :class:`WorkflowPatcherConfig`.
     """
 
-    file_path: Path
-
     @cached_property
     def content(self) -> CommentedMap:
         """
         The loaded YAML content. It loads on first access and
         stays cached even though the class is frozen.
         """
-        loaded_yaml = self.get_yaml_dict(self.file_path)
+        loaded_yaml = self.get_yaml_dict()
         try:
             WorkflowPatcherConfig.model_validate(loaded_yaml)
             return loaded_yaml
diff --git a/exasol/toolbox/util/workflows/process_template.py b/exasol/toolbox/util/workflows/process_template.py
index febebaa35..40cc2ef24 100644
--- a/exasol/toolbox/util/workflows/process_template.py
+++ b/exasol/toolbox/util/workflows/process_template.py
@@ -1,5 +1,3 @@
-from pathlib import Path
-
 from exasol.toolbox.util.workflows.render_yaml import YamlRenderer
 
 
@@ -11,9 +9,9 @@ class WorkflowRenderer(YamlRenderer):
       - standardizing formatting via ruamel.yaml for a consistent output.
     """
 
-    def render(self, file_path: Path) -> str:
+    def render(self) -> str:
         """
         Render the template to the contents of a valid GitHub workflow.
         """
-        workflow_dict = self.get_yaml_dict(file_path)
+        workflow_dict = self.get_yaml_dict()
         return self.get_as_string(workflow_dict)
diff --git a/exasol/toolbox/util/workflows/render_yaml.py b/exasol/toolbox/util/workflows/render_yaml.py
index 7650f58ff..265b95c0d 100644
--- a/exasol/toolbox/util/workflows/render_yaml.py
+++ b/exasol/toolbox/util/workflows/render_yaml.py
@@ -54,6 +54,7 @@ class YamlRenderer:
     """
 
     github_template_dict: dict[str, Any]
+    file_path: Path
 
     @staticmethod
     def _get_standard_yaml() -> YAML:
@@ -74,12 +75,12 @@ def _render_with_jinja(self, input_str: str) -> str:
         jinja_template = jinja_env.from_string(input_str)
         return jinja_template.render(self.github_template_dict)
 
-    def get_yaml_dict(self, file_path: Path) -> CommentedMap:
+    def get_yaml_dict(self) -> CommentedMap:
         """
         Load a file as a CommentedMap (dictionary form of a YAML), after
         rendering it with Jinja.
         """
-        with file_path.open("r", encoding="utf-8") as stream:
+        with self.file_path.open("r", encoding="utf-8") as stream:
             raw_content = stream.read()
 
         try:
@@ -87,9 +88,9 @@ def get_yaml_dict(self, file_path: Path) -> CommentedMap:
             yaml = self._get_standard_yaml()
             return yaml.load(workflow_string)
         except TemplateError as exc:
-            raise TemplateRenderingError(file_path=file_path) from exc
+            raise TemplateRenderingError(file_path=self.file_path) from exc
         except YAMLError as exc:
-            raise YamlSyntaxError(file_path=file_path) from exc
+            raise YamlSyntaxError(file_path=self.file_path) from exc
 
     def get_as_string(self, yaml_dict: CommentedMap) -> str:
         """
diff --git a/exasol/toolbox/util/workflows/workflow.py b/exasol/toolbox/util/workflows/workflow.py
index 4bd02b19b..16a93d171 100644
--- a/exasol/toolbox/util/workflows/workflow.py
+++ b/exasol/toolbox/util/workflows/workflow.py
@@ -19,6 +19,7 @@ def load_from_template(cls, file_path: Path, github_template_dict: dict[str, Any
         if not file_path.exists():
             raise FileNotFoundError(file_path)
 
-        workflow_renderer = WorkflowRenderer(github_template_dict=github_template_dict)
-        workflow = workflow_renderer.render(file_path=file_path)
-        return cls(content=workflow)
+        workflow_renderer = WorkflowRenderer(
+            github_template_dict=github_template_dict, file_path=file_path
+        )
+        return cls(content=workflow_renderer.render())
diff --git a/test/unit/util/workflows/patch_workflow_test.py b/test/unit/util/workflows/patch_workflow_test.py
index 401bdf505..29d344c39 100644
--- a/test/unit/util/workflows/patch_workflow_test.py
+++ b/test/unit/util/workflows/patch_workflow_test.py
@@ -60,7 +60,7 @@ def test_allows_extra_field(
         content = cleandoc(content)
         workflow_patcher_yaml.write_text(content)
 
-        yaml_dict = workflow_patcher.get_yaml_dict(workflow_patcher_yaml)
+        yaml_dict = workflow_patcher.get_yaml_dict()
 
         assert workflow_patcher.get_as_string(yaml_dict) == content
 
diff --git a/test/unit/util/workflows/render_yaml_test.py b/test/unit/util/workflows/render_yaml_test.py
index cd8f33a34..804b40230 100644
--- a/test/unit/util/workflows/render_yaml_test.py
+++ b/test/unit/util/workflows/render_yaml_test.py
@@ -14,13 +14,15 @@
 
 
 @pytest.fixture
-def yaml_renderer() -> YamlRenderer:
-    return YamlRenderer(github_template_dict=PROJECT_CONFIG.github_template_dict)
+def dummy_yaml(tmp_path):
+    return tmp_path / "dummy.yml"
 
 
 @pytest.fixture
-def dummy_yaml(tmp_path):
-    return tmp_path / "dummy.yml"
+def yaml_renderer(dummy_yaml) -> YamlRenderer:
+    return YamlRenderer(
+        github_template_dict=PROJECT_CONFIG.github_template_dict, file_path=dummy_yaml
+    )
 
 
 class TestYamlRenderer:
@@ -44,7 +46,7 @@ def test_works_for_general_case(dummy_yaml, yaml_renderer):
         content = cleandoc(input_yaml)
         dummy_yaml.write_text(content)
 
-        yaml_dict = yaml_renderer.get_yaml_dict(dummy_yaml)
+        yaml_dict = yaml_renderer.get_yaml_dict()
         assert yaml_renderer.get_as_string(yaml_dict) == cleandoc(input_yaml)
 
     @staticmethod
@@ -73,7 +75,7 @@ def test_fixes_extra_horizontal_whitespace(dummy_yaml, yaml_renderer):
         content = cleandoc(input_yaml)
         dummy_yaml.write_text(content)
 
-        yaml_dict = yaml_renderer.get_yaml_dict(dummy_yaml)
+        yaml_dict = yaml_renderer.get_yaml_dict()
         assert yaml_renderer.get_as_string(yaml_dict) == cleandoc(expected_yaml)
 
     @staticmethod
@@ -97,7 +99,7 @@ def test_keeps_comments(dummy_yaml, yaml_renderer):
         content = cleandoc(input_yaml)
         dummy_yaml.write_text(content)
 
-        yaml_dict = yaml_renderer.get_yaml_dict(dummy_yaml)
+        yaml_dict = yaml_renderer.get_yaml_dict()
         assert yaml_renderer.get_as_string(yaml_dict) == cleandoc(expected_yaml)
 
     @staticmethod
@@ -141,7 +143,7 @@ def test_keeps_quotes_for_variables_as_is(dummy_yaml, yaml_renderer):
         content = cleandoc(input_yaml)
         dummy_yaml.write_text(content)
 
-        yaml_dict = yaml_renderer.get_yaml_dict(dummy_yaml)
+        yaml_dict = yaml_renderer.get_yaml_dict()
         assert yaml_renderer.get_as_string(yaml_dict) == cleandoc(expected_yaml)
 
     @staticmethod
@@ -164,7 +166,7 @@ def test_updates_jinja_variables(dummy_yaml, yaml_renderer):
         content = cleandoc(input_yaml)
         dummy_yaml.write_text(content)
 
-        yaml_dict = yaml_renderer.get_yaml_dict(dummy_yaml)
+        yaml_dict = yaml_renderer.get_yaml_dict()
         assert yaml_renderer.get_as_string(yaml_dict) == cleandoc(expected_yaml)
 
     @staticmethod
@@ -188,7 +190,7 @@ def test_preserves_list_format(dummy_yaml, yaml_renderer):
         content = cleandoc(input_yaml)
         dummy_yaml.write_text(content)
 
-        yaml_dict = yaml_renderer.get_yaml_dict(dummy_yaml)
+        yaml_dict = yaml_renderer.get_yaml_dict()
         assert yaml_renderer.get_as_string(yaml_dict) == cleandoc(input_yaml)
 
     @staticmethod
@@ -206,7 +208,7 @@ def test_jinja_variable_unknown(dummy_yaml, yaml_renderer):
         with pytest.raises(
             TemplateRenderingError, match="Check Jinja2-related errors."
         ) as exc:
-            yaml_renderer.get_yaml_dict(dummy_yaml)
+            yaml_renderer.get_yaml_dict()
         assert isinstance(exc.value.__cause__, UndefinedError)
         assert "'bad_jinja' is undefined" in str(exc.value.__cause__)
 
@@ -225,6 +227,6 @@ def test_jinja_variable_unclosed(dummy_yaml, yaml_renderer):
         with pytest.raises(
             TemplateRenderingError, match="Check Jinja2-related errors."
         ) as exc:
-            yaml_renderer.get_yaml_dict(dummy_yaml)
+            yaml_renderer.get_yaml_dict()
         assert isinstance(exc.value.__cause__, TemplateSyntaxError)
         assert "unexpected ')'" in str(exc.value.__cause__)

From 811ae802affb120b8e90baeafd3ee4ad7a630acd Mon Sep 17 00:00:00 2001
From: Ariel Schulz <ariel.schulz@exasol.com>
Date: Fri, 13 Feb 2026 10:09:38 +0100
Subject: [PATCH 07/10] Switch these to fixtures as will be resused for unit
 tests

---
 test/unit/util/workflows/conftest.py          | 36 +++++++++++++++++
 .../util/workflows/patch_workflow_test.py     | 40 +++++--------------
 2 files changed, 45 insertions(+), 31 deletions(-)

diff --git a/test/unit/util/workflows/conftest.py b/test/unit/util/workflows/conftest.py
index 730e6caa6..32b0d8032 100644
--- a/test/unit/util/workflows/conftest.py
+++ b/test/unit/util/workflows/conftest.py
@@ -1,7 +1,12 @@
 from dataclasses import dataclass
+from inspect import cleandoc
+from pathlib import Path
 
 import pytest
 
+from exasol.toolbox.util.workflows.patch_workflow import WorkflowPatcher
+from noxconfig import PROJECT_CONFIG
+
 
 @dataclass(frozen=True)
 class ExamplePatcherYaml:
@@ -30,3 +35,34 @@ class ExamplePatcherYaml:
 @pytest.fixture(scope="session")
 def example_patcher_yaml():
     return ExamplePatcherYaml
+
+
+@pytest.fixture
+def workflow_patcher_yaml(tmp_path: Path) -> Path:
+    return tmp_path / ".workflow-patcher.yml"
+
+
+@pytest.fixture
+def workflow_patcher(workflow_patcher_yaml) -> WorkflowPatcher:
+    return WorkflowPatcher(
+        github_template_dict=PROJECT_CONFIG.github_template_dict,
+        file_path=workflow_patcher_yaml,
+    )
+
+
+@pytest.fixture
+def remove_job_yaml(example_patcher_yaml, workflow_patcher_yaml):
+    content = cleandoc(example_patcher_yaml.remove_jobs)
+    workflow_patcher_yaml.write_text(content)
+    return content
+
+
+@pytest.fixture
+def step_customization_yaml(request, example_patcher_yaml, workflow_patcher_yaml):
+    # request.param will hold the value passed from @pytest.mark.parametrize
+    action_value = request.param
+
+    text = example_patcher_yaml.step_customization.format(action=action_value)
+    content = cleandoc(text)
+    workflow_patcher_yaml.write_text(content)
+    return content
diff --git a/test/unit/util/workflows/patch_workflow_test.py b/test/unit/util/workflows/patch_workflow_test.py
index 29d344c39..dbe3c7f0f 100644
--- a/test/unit/util/workflows/patch_workflow_test.py
+++ b/test/unit/util/workflows/patch_workflow_test.py
@@ -1,5 +1,4 @@
 from inspect import cleandoc
-from pathlib import Path
 
 import pytest
 from pydantic import ValidationError
@@ -7,45 +6,24 @@
 from exasol.toolbox.util.workflows.patch_workflow import (
     ActionType,
     InvalidWorkflowPatcherYamlError,
-    WorkflowPatcher,
 )
-from noxconfig import PROJECT_CONFIG
-
-
-@pytest.fixture
-def workflow_patcher(workflow_patcher_yaml) -> WorkflowPatcher:
-    return WorkflowPatcher(
-        github_template_dict=PROJECT_CONFIG.github_template_dict,
-        file_path=workflow_patcher_yaml,
-    )
-
-
-@pytest.fixture
-def workflow_patcher_yaml(tmp_path: Path) -> Path:
-    return tmp_path / ".workflow-patcher.yml"
 
 
 class TestWorkflowPatcher:
     @staticmethod
-    def test_remove_jobs(example_patcher_yaml, workflow_patcher_yaml, workflow_patcher):
-        content = cleandoc(example_patcher_yaml.remove_jobs)
-        workflow_patcher_yaml.write_text(content)
-
+    def test_remove_jobs(remove_job_yaml, workflow_patcher):
         result = workflow_patcher.content
-        assert workflow_patcher.get_as_string(result) == content
+        assert workflow_patcher.get_as_string(result) == remove_job_yaml
 
     @staticmethod
-    @pytest.mark.parametrize("action", ActionType)
-    def test_step_customizations(
-        example_patcher_yaml, workflow_patcher_yaml, action, workflow_patcher
-    ):
-        content = cleandoc(
-            example_patcher_yaml.step_customization.format(action=action.value)
-        )
-        workflow_patcher_yaml.write_text(content)
-
+    @pytest.mark.parametrize(
+        "step_customization_yaml",
+        [action.value for action in ActionType],
+        indirect=True,
+    )
+    def test_step_customizations(step_customization_yaml, workflow_patcher):
         result = workflow_patcher.content
-        assert workflow_patcher.get_as_string(result) == content
+        assert workflow_patcher.get_as_string(result) == step_customization_yaml
 
 
 class TestStepCustomization:

From 946f3e809ee2afdbff1124d1535177eb915abf96 Mon Sep 17 00:00:00 2001
From: Ariel Schulz <ariel.schulz@exasol.com>
Date: Fri, 13 Feb 2026 10:59:56 +0100
Subject: [PATCH 08/10] Add extract_by_workflow and test

---
 .../toolbox/util/workflows/patch_workflow.py  | 13 ++++++++++
 .../util/workflows/patch_workflow_test.py     | 26 +++++++++++++++++++
 2 files changed, 39 insertions(+)

diff --git a/exasol/toolbox/util/workflows/patch_workflow.py b/exasol/toolbox/util/workflows/patch_workflow.py
index 2e2657d7d..a4f2ca636 100644
--- a/exasol/toolbox/util/workflows/patch_workflow.py
+++ b/exasol/toolbox/util/workflows/patch_workflow.py
@@ -115,3 +115,16 @@ def content(self) -> CommentedMap:
             return loaded_yaml
         except ValidationError as exc:
             raise InvalidWorkflowPatcherYamlError(file_path=self.file_path) from exc
+
+    def extract_by_workflow(self, workflow_name: str) -> CommentedMap | None:
+        """
+        Extract from the `content` where `name` matches the `workflow_name`.
+        If the workflow is not found, then `None` is returned. It is an expected and
+        common use case that the `WorkflowPatcher` would only modify a few workflows
+        and not all of them.
+        """
+        inner_content = self.content["workflows"]
+        for workflow in inner_content:
+            if workflow["name"] == workflow_name:
+                return workflow
+        return None
diff --git a/test/unit/util/workflows/patch_workflow_test.py b/test/unit/util/workflows/patch_workflow_test.py
index dbe3c7f0f..8bea1fe7c 100644
--- a/test/unit/util/workflows/patch_workflow_test.py
+++ b/test/unit/util/workflows/patch_workflow_test.py
@@ -2,6 +2,7 @@
 
 import pytest
 from pydantic import ValidationError
+from ruamel.yaml import CommentedMap
 
 from exasol.toolbox.util.workflows.patch_workflow import (
     ActionType,
@@ -25,6 +26,31 @@ def test_step_customizations(step_customization_yaml, workflow_patcher):
         result = workflow_patcher.content
         assert workflow_patcher.get_as_string(result) == step_customization_yaml
 
+    @staticmethod
+    def test_extract_by_workflow_works_as_expected(
+        example_patcher_yaml, workflow_patcher_yaml, workflow_patcher
+    ):
+        content = f"""
+        {example_patcher_yaml.remove_jobs}
+        - name: "pr-merge.yml"
+          remove_jobs:
+           - publish-docs
+        """
+        content = cleandoc(content)
+        workflow_patcher_yaml.write_text(content)
+
+        result = workflow_patcher.extract_by_workflow("pr-merge.yml")
+        assert result == CommentedMap(
+            {"name": "pr-merge.yml", "remove_jobs": ["publish-docs"]}
+        )
+
+    @staticmethod
+    def test_extract_by_workflow_not_found_returns_none(
+        remove_job_yaml, workflow_patcher
+    ):
+        result = workflow_patcher.extract_by_workflow("pr-merge.yml")
+        assert result is None
+
 
 class TestStepCustomization:
     @staticmethod

From a654651986e3ea2daf0b73c6489d9b7c8abeceaf Mon Sep 17 00:00:00 2001
From: Ariel Schulz <ariel.schulz@exasol.com>
Date: Fri, 13 Feb 2026 11:02:24 +0100
Subject: [PATCH 09/10] Update docstring

---
 exasol/toolbox/util/workflows/patch_workflow.py | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/exasol/toolbox/util/workflows/patch_workflow.py b/exasol/toolbox/util/workflows/patch_workflow.py
index a4f2ca636..6f96a27d8 100644
--- a/exasol/toolbox/util/workflows/patch_workflow.py
+++ b/exasol/toolbox/util/workflows/patch_workflow.py
@@ -98,9 +98,9 @@ class WorkflowPatcherConfig(BaseModel):
 class WorkflowPatcher(YamlRenderer):
     """
     The :class:`WorkflowPatcher` enables users to define a YAML file
-    to customize PTB-provided workflows by removing or modifying jobs in the file.
-    A job can be modified by replacing or inserting steps.
-    The provided YAML file must meet the conditions of :class:`WorkflowPatcherConfig`.
+    to customize PTB-provided workflows by removing or modifying jobs.
+    A job can be modified by replacing or inserting steps. The provided
+    YAML file must meet the conditions of :class:`WorkflowPatcherConfig`.
     """
 
     @cached_property

From a03971f838a98db134af01404f4de27fd6d744a6 Mon Sep 17 00:00:00 2001
From: Ariel Schulz <ariel.schulz@exasol.com>
Date: Fri, 13 Feb 2026 11:52:23 +0100
Subject: [PATCH 10/10] Add class to patch the workflow & tests to verify but
 do not activate yet

---
 .../toolbox/util/workflows/patch_workflow.py  |  22 ++-
 .../util/workflows/process_template.py        |  93 ++++++++++
 test/unit/util/workflows/conftest.py          |   4 +-
 .../util/workflows/process_template_test.py   | 165 ++++++++++++++++++
 4 files changed, 280 insertions(+), 4 deletions(-)
 create mode 100644 test/unit/util/workflows/process_template_test.py

diff --git a/exasol/toolbox/util/workflows/patch_workflow.py b/exasol/toolbox/util/workflows/patch_workflow.py
index 6f96a27d8..9947caea8 100644
--- a/exasol/toolbox/util/workflows/patch_workflow.py
+++ b/exasol/toolbox/util/workflows/patch_workflow.py
@@ -4,7 +4,11 @@
 from enum import Enum
 from functools import cached_property
 from pathlib import Path
-from typing import Any
+from typing import (
+    Annotated,
+    Any,
+    TypeAlias,
+)
 
 from pydantic import (
     BaseModel,
@@ -94,6 +98,20 @@ class WorkflowPatcherConfig(BaseModel):
     workflows: list[Workflow]
 
 
+WorkflowCommentedMap: TypeAlias = Annotated[
+    CommentedMap, f"This CommentedMap is structured according to `{Workflow.__name__}`"
+]
+
+StepCustomizationCommentedMap: TypeAlias = Annotated[
+    CommentedMap,
+    f"This CommentedMap is structured according to `{StepCustomization.__name__}`",
+]
+StepsCommentedMap: TypeAlias = Annotated[
+    CommentedMap,
+    f"This CommentedMap is structured according to `list[{StepContent.__name__}]`",
+]
+
+
 @dataclass(frozen=True)
 class WorkflowPatcher(YamlRenderer):
     """
@@ -116,7 +134,7 @@ def content(self) -> CommentedMap:
         except ValidationError as exc:
             raise InvalidWorkflowPatcherYamlError(file_path=self.file_path) from exc
 
-    def extract_by_workflow(self, workflow_name: str) -> CommentedMap | None:
+    def extract_by_workflow(self, workflow_name: str) -> WorkflowCommentedMap | None:
         """
         Extract from the `content` where `name` matches the `workflow_name`.
         If the workflow is not found, then `None` is returned. It is an expected and
diff --git a/exasol/toolbox/util/workflows/process_template.py b/exasol/toolbox/util/workflows/process_template.py
index 40cc2ef24..35fb1e345 100644
--- a/exasol/toolbox/util/workflows/process_template.py
+++ b/exasol/toolbox/util/workflows/process_template.py
@@ -1,6 +1,18 @@
+import copy
+from dataclasses import dataclass
+
+from ruamel.yaml import CommentedMap
+
+from exasol.toolbox.util.workflows.patch_workflow import (
+    ActionType,
+    StepCustomizationCommentedMap,
+    StepsCommentedMap,
+    WorkflowCommentedMap,
+)
 from exasol.toolbox.util.workflows.render_yaml import YamlRenderer
 
 
+@dataclass(frozen=True)
 class WorkflowRenderer(YamlRenderer):
     """
     The :class:`WorkflowRenderer` renders a workflow template provided by the PTB into
@@ -9,9 +21,90 @@ class WorkflowRenderer(YamlRenderer):
       - standardizing formatting via ruamel.yaml for a consistent output.
     """
 
+    patch_yaml: WorkflowCommentedMap | None = None
+
     def render(self) -> str:
         """
         Render the template to the contents of a valid GitHub workflow.
         """
         workflow_dict = self.get_yaml_dict()
+
+        if self.patch_yaml:
+            workflow_modifier = WorkflowPatcher(
+                workflow_dict=workflow_dict, patch_yaml=self.patch_yaml
+            )
+            workflow_dict = workflow_modifier.get_patched_workflow()
+
         return self.get_as_string(workflow_dict)
+
+
+@dataclass(frozen=True)
+class WorkflowPatcher:
+    workflow_dict: WorkflowCommentedMap
+    patch_yaml: CommentedMap
+
+    def __post_init__(self):
+        # Perform deepcopy to ensure this instance owns its data
+        # Use object.__setattr__ because the dataclass is frozen
+        object.__setattr__(self, "workflow_dict", copy.deepcopy(self.workflow_dict))
+
+    @property
+    def jobs_dict(self) -> CommentedMap:
+        return self.workflow_dict["jobs"]
+
+    def _get_step_list(self, job_name: str) -> StepsCommentedMap:
+        self._verify_job_exists(job_name=job_name)
+        return self.jobs_dict[job_name]["steps"]
+
+    def _customize_steps(
+        self, step_customizations: StepCustomizationCommentedMap
+    ) -> None:
+        """
+        Customize the steps of jobs specified in `step_customizations` in a workflow
+        (`workflow_dict`). If a `step_id` or its parent `job` cannot be found, an
+        exception is raised.
+        """
+        for patch in step_customizations:
+            job_name = patch["job"]
+            idx = self._get_step_index(job_name=job_name, step_id=patch["step_id"])
+
+            step_list = self._get_step_list(job_name=job_name)
+            if patch["action"] == ActionType.REPLACE.value:
+                step_list[idx : idx + 1] = patch["content"]
+            elif patch["action"] == ActionType.INSERT_AFTER.value:
+                step_list[idx + 1 : idx + 1] = patch["content"]
+
+    def _get_step_index(self, job_name: str, step_id: str) -> int:
+        steps = self._get_step_list(job_name=job_name)
+        for index, step in enumerate(steps):
+            if step["id"] == step_id:
+                return index
+        raise ValueError(f"step_id '{step_id}' not found in job '{job_name}'")
+
+    def _remove_jobs(self, remove_jobs: CommentedMap) -> None:
+        """
+        Remove the jobs specified in `remove_jobs` in a workflow yaml (`workflow_dict`).
+        If a `job` cannot be found, an exception is raised.
+        """
+        for job_name in remove_jobs:
+            self._verify_job_exists(job_name)
+            self.jobs_dict.pop(job_name)
+
+    def _verify_job_exists(self, job_name: str) -> None:
+        if job_name not in self.jobs_dict:
+            raise ValueError(f"job '{job_name}' not found")
+
+    def get_patched_workflow(self):
+        """
+        Patch the `workflow_dict`. As dictionaries are mutable structures, we directly
+        take advantage of this by having it modified in this class's internal methods
+        without explicit returns.
+        """
+
+        if remove_jobs := self.patch_yaml.get("remove_jobs", {}):
+            self._remove_jobs(remove_jobs=remove_jobs)
+
+        if step_customizations := self.patch_yaml.get("step_customizations", {}):
+            self._customize_steps(step_customizations=step_customizations)
+
+        return self.workflow_dict
diff --git a/test/unit/util/workflows/conftest.py b/test/unit/util/workflows/conftest.py
index 32b0d8032..f2ad2a416 100644
--- a/test/unit/util/workflows/conftest.py
+++ b/test/unit/util/workflows/conftest.py
@@ -24,8 +24,8 @@ class ExamplePatcherYaml:
               job: run-unit-tests
               step_id: check-out-repository
               content:
-                - name: SCM Checkout
-                  id: checkout-repo
+                - name: Check out Repository
+                  id: check-out-repository
                   uses: actions/checkout@v6
                   with:
                     fetch-depth: 0
diff --git a/test/unit/util/workflows/process_template_test.py b/test/unit/util/workflows/process_template_test.py
new file mode 100644
index 000000000..a218522b5
--- /dev/null
+++ b/test/unit/util/workflows/process_template_test.py
@@ -0,0 +1,165 @@
+import pytest
+from ruamel.yaml import CommentedMap
+
+from exasol.toolbox.util.workflows.patch_workflow import ActionType
+from exasol.toolbox.util.workflows.process_template import WorkflowPatcher
+from exasol.toolbox.util.workflows.render_yaml import YamlRenderer
+from noxconfig import PROJECT_CONFIG
+
+WORKFLOW_YAML = """
+name: Checks
+
+on:
+  workflow_call:
+
+jobs:
+  build-documentation-and-check-links:
+    name: Docs
+    runs-on: "ubuntu-24.04"
+    permissions:
+      contents: read
+    steps:
+      - name: Check out Repository
+        id: check-out-repository
+        uses: actions/checkout@v6
+
+  run-unit-tests:
+    name: Run Unit Tests (Python-${{ matrix.python-versions }})
+    runs-on: "ubuntu-24.04"
+    permissions:
+      contents: read
+    strategy:
+      fail-fast: false
+      matrix:
+        python-versions: ["3.10", "3.11", "3.12", "3.13", "3.14"]
+
+    steps:
+      - name: Check out Repository
+        id: check-out-repository
+        uses: actions/checkout@v6
+
+"""
+
+
+@pytest.fixture
+def workflow_name():
+    return "checks.yml"
+
+
+@pytest.fixture
+def checks_yaml(tmp_path, workflow_name):
+    file_path = tmp_path / workflow_name
+    file_path.write_text(WORKFLOW_YAML)
+    return file_path
+
+
+@pytest.fixture
+def workflow_dict(checks_yaml) -> CommentedMap:
+    return YamlRenderer(
+        github_template_dict=PROJECT_CONFIG.github_template_dict, file_path=checks_yaml
+    ).get_yaml_dict()
+
+
+class TestWorkflowModifier:
+    @staticmethod
+    def test__remove_jobs(
+        workflow_name, workflow_dict, workflow_patcher, remove_job_yaml
+    ):
+        workflow_patcher = WorkflowPatcher(
+            workflow_dict=workflow_dict,
+            patch_yaml=workflow_patcher.extract_by_workflow(workflow_name),
+        )
+
+        result = workflow_patcher.get_patched_workflow()
+
+        # The original was not altered as it was deepcopied before modifications.
+        assert list(workflow_dict["jobs"].keys()) == [
+            "build-documentation-and-check-links",
+            "run-unit-tests",
+        ]
+        # The original and resulting workflows should have the same values here.
+        assert result["name"] == workflow_dict["name"]
+        assert result["on"] == workflow_dict["on"]
+        assert (
+            result["jobs"]["run-unit-tests"] == workflow_dict["jobs"]["run-unit-tests"]
+        )
+        # The resulting workflow has job "build-documentation-and-check-links" removed.
+        assert list(result["jobs"].keys()) == ["run-unit-tests"]
+
+    @staticmethod
+    @pytest.mark.parametrize(
+        "step_customization_yaml",
+        [ActionType.REPLACE.value],
+        indirect=True,
+    )
+    def test__customize_steps_replacement(
+        workflow_name, workflow_dict, workflow_patcher, step_customization_yaml
+    ):
+        workflow_patcher = WorkflowPatcher(
+            workflow_dict=workflow_dict,
+            patch_yaml=workflow_patcher.extract_by_workflow(workflow_name),
+        )
+
+        result = workflow_patcher.get_patched_workflow()
+
+        # The original and resulting workflows should have the same values here.
+        assert result["name"] == workflow_dict["name"]
+        assert result["on"] == workflow_dict["on"]
+        assert list(result["jobs"].keys()) == list(workflow_dict["jobs"].keys())
+        assert (
+            result["jobs"]["build-documentation-and-check-links"]
+            == workflow_dict["jobs"]["build-documentation-and-check-links"]
+        )
+        # The replaced step (in job `run-unit-tests`, at step `check-out-repository`)
+        # has a `with`.
+        assert result["jobs"]["run-unit-tests"]["steps"][0].pop("with") == CommentedMap(
+            {"fetch-depth": 0}
+        )
+        # Without the `with`, they should be the same, as that's how the test is set up.
+        assert (
+            result["jobs"]["run-unit-tests"] == workflow_dict["jobs"]["run-unit-tests"]
+        )
+
+    @staticmethod
+    @pytest.mark.parametrize(
+        "step_customization_yaml",
+        [ActionType.INSERT_AFTER.value],
+        indirect=True,
+    )
+    def test__customize_steps_insertion_after(
+        workflow_name, workflow_dict, workflow_patcher, step_customization_yaml
+    ):
+        workflow_patcher = WorkflowPatcher(
+            workflow_dict=workflow_dict,
+            patch_yaml=workflow_patcher.extract_by_workflow(workflow_name),
+        )
+
+        result = workflow_patcher.get_patched_workflow()
+
+        # The original and internal workflows should have the same values here.
+        assert result["name"] == workflow_dict["name"]
+        assert result["on"] == workflow_dict["on"]
+        assert (
+            result["jobs"]["build-documentation-and-check-links"]
+            == workflow_dict["jobs"]["build-documentation-and-check-links"]
+        )
+        # The insert after job added a step at the end of `run-unit-tests`.
+        assert (
+            len(result["jobs"]["run-unit-tests"]["steps"])
+            == len(workflow_dict["jobs"]["run-unit-tests"]["steps"]) + 1
+            == 2
+        )
+        assert (
+            result["jobs"]["run-unit-tests"]["steps"][0]
+            == workflow_dict["jobs"]["run-unit-tests"]["steps"][0]
+        )
+        # The inserted after was done after step (in job `run-unit-tests`, at step
+        # `check-out-repository`). It has a `with` but is otherwise identical to
+        # the preceding step.
+        assert result["jobs"]["run-unit-tests"]["steps"][1].pop("with") == CommentedMap(
+            {"fetch-depth": 0}
+        )
+        assert (
+            result["jobs"]["run-unit-tests"]["steps"][1]
+            == result["jobs"]["run-unit-tests"]["steps"][0]
+        )