diff --git a/.bazelignore b/.bazelignore
index 52a7f545..d3dcf303 100644
--- a/.bazelignore
+++ b/.bazelignore
@@ -13,3 +13,5 @@
 
 python_basics/integration_tests
 starpls/integration_tests
+# Should be run from its own directory (separate Module)
+bazel/rules/rules_score/test
diff --git a/.bazelrc b/.bazelrc
index 9b663e7c..6d10fbb4 100644
--- a/.bazelrc
+++ b/.bazelrc
@@ -7,6 +7,11 @@ common --registry=https://bcr.bazel.build
 
 common --extra_toolchains=@score_gcc_x86_64_toolchain//:x86_64-linux
 
+# libclang toolchain for the C/C++ parser used by the score rules. Registered
+# only for score_tooling's own build (its LLVM is a dev dependency); integrating
+# repositories register their own libclang toolchain instead.
+common --extra_toolchains=//cpp/libclang:score_tooling_libclang_toolchain
+
 build --java_language_version=17
 build --tool_java_language_version=17
 build --java_runtime_version=remotejdk_17
diff --git a/.bazelversion b/.bazelversion
index 56b6be4e..f9c71a52 100644
--- a/.bazelversion
+++ b/.bazelversion
@@ -1 +1 @@
-8.3.1
+8.5.1
diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index 66745e31..51686a5d 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -14,34 +14,36 @@ name: Run Python Basics Integration and Unit Tests
 on:
   pull_request:
     types: [opened, reopened, synchronize]
+concurrency:
+  group: tests-${{ github.event.pull_request.number || github.run_id }}
+  cancel-in-progress: ${{ github.event_name == 'pull_request' }}
+env:
+  ANDROID_HOME: ""
+  ANDROID_SDK_ROOT: ""
+  FORCE_JAVASCRIPT_ACTIONS_TO_NODE24: true
 jobs:
-  code:
-    runs-on: ubuntu-latest
+  root_workspace_tests:
+    runs-on: ubuntu-24.04
+    permissions:
+      contents: read
+      actions: write
     steps:
       - name: Checkout repository
         uses: actions/checkout@v7.0.0
-      - name: Install Missing Dependencies
-        run: |
-          sudo apt-get update
-          sudo apt-get install -y libcairo2-dev
-      - name: Run python_basics integration tests
-        run: |
-          cd python_basics/integration_tests
-          bazel test //...
-      - name: Run starpls integration tests
-        run: |
-          cd starpls/integration_tests
-          bazel test //...
-      - name: Run cr_checker unit tests
-        run: |
-          cd cr_checker/tests
-          bazel test //...
+      - name: Free Disk Space (Ubuntu)
+        uses: eclipse-score/more-disk-space@v1
+        with:
+          level: 4
+      - uses: castler/setup-bazel@cache-optimized
+        with:
+          bazelisk-cache: true
+          disk-cache: root_workspace_tests
+          repository-cache: true
+          cache-optimized: true
+          cache-save: ${{ github.ref == 'refs/heads/main' }}
       - name: Run coverage module tests
         run: |
           bazel test //coverage/tests:all
-      - name: Run rules_score tests
-        run: |
-          bazel test //bazel/rules/rules_score/...
       - name: Run Plantuml Tooling clippy
         run: |
           bazel build //plantuml/... --config=clippy
@@ -63,3 +65,61 @@ jobs:
       - name: Run Libclang Parser Tooling tests
         run: |
           bazel test //cpp/libclang/...
+  integration_tests:
+    runs-on: ubuntu-24.04
+    permissions:
+      contents: read
+      actions: write
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v7.0.0
+      - name: Free Disk Space (Ubuntu)
+        uses: eclipse-score/more-disk-space@v1
+        with:
+          level: 4
+      - uses: castler/setup-bazel@cache-optimized
+        with:
+          bazelisk-cache: true
+          disk-cache: integration_tests
+          repository-cache: true
+          cache-optimized: true
+          cache-save: ${{ github.ref == 'refs/heads/main' }}
+      - name: Run python_basics integration tests
+        run: |
+          cd python_basics/integration_tests
+          bazel test //...
+      - name: Run starpls integration tests
+        run: |
+          cd starpls/integration_tests
+          bazel test //...
+      - name: Run cr_checker unit tests
+        run: |
+          cd cr_checker/tests
+          bazel test //...
+  rules_score_tests:
+    runs-on: ubuntu-24.04
+    permissions:
+      contents: read
+      actions: write
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v7.0.0
+      - name: Free Disk Space (Ubuntu)
+        uses: eclipse-score/more-disk-space@v1
+        with:
+          level: 4
+      - uses: castler/setup-bazel@cache-optimized
+        with:
+          bazelisk-cache: true
+          disk-cache: rules_score_tests
+          repository-cache: true
+          cache-optimized: true
+          cache-save: ${{ github.ref == 'refs/heads/main' }}
+      - name: Install Missing Dependencies
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y libcairo2-dev
+      - name: Run rules_score tests
+        run: |
+          cd bazel/rules/rules_score/test
+          bazel test //...
diff --git a/bazel/rules/rules_score/private/sphinx_module.bzl b/bazel/rules/rules_score/private/sphinx_module.bzl
index 1a2007f4..ac230727 100644
--- a/bazel/rules/rules_score/private/sphinx_module.bzl
+++ b/bazel/rules/rules_score/private/sphinx_module.bzl
@@ -414,12 +414,6 @@ def sphinx_module(
                     extension will not be available).
         visibility: Bazel visibility
     """
-    if graphviz == None:
-        graphviz = select({
-            "//bazel/rules/rules_score:linux_x86_64": "@graphviz_deb//:all",
-            "//conditions:default": None,
-        })
-
     _score_needs(
         name = name + "_needs",
         srcs = srcs,
diff --git a/bazel/rules/rules_score/private/unit.bzl b/bazel/rules/rules_score/private/unit.bzl
index e6869f85..5169923b 100644
--- a/bazel/rules/rules_score/private/unit.bzl
+++ b/bazel/rules/rules_score/private/unit.bzl
@@ -25,7 +25,7 @@ load("@rules_cc//cc:find_cc_toolchain.bzl", "use_cc_toolchain")
 load("@rules_cc//cc/common:cc_info.bzl", "CcInfo")
 load("@rules_rust//rust:defs.bzl", "rust_common")
 load("//bazel/rules/rules_score:providers.bzl", "CcDependencyInfo", "CertifiedScope", "SphinxSourcesInfo", "UnitDesignInfo", "UnitInfo")
-load("//cpp/libclang:cpp_parser.bzl", "cpp_parser_action_internal_attrs", "cpp_parser_target_aspects", "has_cpp_parser_inputs", "run_cpp_parser_action")
+load("//cpp/libclang:cpp_parser.bzl", "cpp_parser_action_internal_attrs", "cpp_parser_action_toolchains", "cpp_parser_target_aspects", "has_cpp_parser_inputs", "run_cpp_parser_action")
 load(":cc_dependency_aspect.bzl", "cc_dependencies_aspect")
 
 def _run_implementation_cpp_parser(ctx, impl, output_prefix):
@@ -34,9 +34,6 @@ def _run_implementation_cpp_parser(ctx, impl, output_prefix):
         target = impl,
         output_prefix = output_prefix,
         tool = ctx.attr._tool,
-        libclang = ctx.file._libclang,
-        llvm_cxx_builtin_include = ctx.attr._llvm_cxx_builtin_include,
-        llvm_extra_config_site = ctx.attr._llvm_extra_config_site,
         log_level = ctx.attr._log_level[BuildSettingInfo].value,
     )
 
@@ -167,7 +164,7 @@ _unit = rule(
     doc = "Defines a software unit with design, implementation, and tests for S-CORE process compliance",
     subrules = [subrule_gtest_report],
     attrs = _unit_attrs,
-    toolchains = use_cc_toolchain(),
+    toolchains = cpp_parser_action_toolchains() + use_cc_toolchain(),
     fragments = ["cpp"],
 )
 
diff --git a/bazel/rules/rules_score/private/verbosity.bzl b/bazel/rules/rules_score/private/verbosity.bzl
index b5863eda..a8388e74 100644
--- a/bazel/rules/rules_score/private/verbosity.bzl
+++ b/bazel/rules/rules_score/private/verbosity.bzl
@@ -44,7 +44,7 @@ load("@bazel_skylib//rules:common_settings.bzl", "BuildSettingInfo")
 # Merge into a rule's attrs dict with ``**VERBOSITY_ATTR``.
 VERBOSITY_ATTR = {
     "_verbosity": attr.label(
-        default = Label("//bazel/rules/rules_score:verbosity"),
+        default = Label("@score_tooling//bazel/rules/rules_score:verbosity"),
         doc = "Verbosity level build setting (warn/info/debug).",
     ),
 }
diff --git a/bazel/rules/rules_score/test/.bazelversion b/bazel/rules/rules_score/test/.bazelversion
index 56b6be4e..f9c71a52 100644
--- a/bazel/rules/rules_score/test/.bazelversion
+++ b/bazel/rules/rules_score/test/.bazelversion
@@ -1 +1 @@
-8.3.1
+8.5.1
diff --git a/bazel/rules/rules_score/test/BUILD b/bazel/rules/rules_score/test/BUILD
index d4b879cb..2c0b4e11 100644
--- a/bazel/rules/rules_score/test/BUILD
+++ b/bazel/rules/rules_score/test/BUILD
@@ -1,3 +1,5 @@
+load("@aspect_rules_py//py:defs.bzl", "py_binary")
+
 # *******************************************************************************
 # Copyright (c) 2025 Contributors to the Eclipse Foundation
 #
@@ -26,6 +28,8 @@ load(
     "unit",
     "unit_design",
 )
+load("@score_tooling//bazel/rules/rules_score:sphinx_toolchain.bzl", "sphinx_toolchain")
+load("@score_tooling//cpp/libclang:libclang_toolchain.bzl", "libclang_toolchain")
 load("@trlc//:trlc.bzl", "trlc_requirements", "trlc_requirements_test")
 load(
     ":html_generation_test.bzl",
@@ -93,6 +97,56 @@ load(
 
 package(default_visibility = ["//visibility:public"])
 
+# ============================================================================
+# Sphinx Toolchain — uses score_docs_as_code so score_metamodel is importable
+# ============================================================================
+
+exports_files(["template/conf.template.py"])
+
+py_binary(
+    name = "score_build",
+    srcs = ["@score_tooling//bazel/rules/rules_score:src/sphinx_wrapper.py"],
+    main = "@score_tooling//bazel/rules/rules_score:src/sphinx_wrapper.py",
+    package_collisions = "warning",
+    visibility = ["//visibility:public"],
+    deps = [
+        "@score_docs_as_code//src:plantuml_for_python",
+        "@score_docs_as_code//src/extensions/score_sphinx_bundle",
+        "@score_tooling//bazel/rules/rules_score:bazel_sphinx_needs",
+        "@score_tooling//bazel/rules/rules_score:sphinx_module_ext",
+    ],
+)
+
+sphinx_toolchain(
+    name = "score_sphinx_toolchain",
+    conf_template = "//:template/conf.template.py",
+    html_merge_tool = "@score_tooling//bazel/rules/rules_score:sphinx_html_merge",
+    sphinx = ":score_build",
+)
+
+toolchain(
+    name = "score_toolchain",
+    toolchain = ":score_sphinx_toolchain",
+    toolchain_type = "@score_tooling//bazel/rules/rules_score:toolchain_type",
+)
+
+# ============================================================================
+# libclang Toolchain — this integrating repo supplies its own libclang/C++
+# toolchain for the score libclang-based C/C++ parser.
+# ============================================================================
+libclang_toolchain(
+    name = "test_libclang",
+    cxx_builtin_include = "@llvm_toolchain_llvm//:cxx_builtin_include",
+    extra_config_site = "@llvm_toolchain_llvm//:extra_config_site",
+    libclang = "@llvm_toolchain_llvm//:lib/libclang.so",
+)
+
+toolchain(
+    name = "test_libclang_toolchain",
+    toolchain = ":test_libclang",
+    toolchain_type = "@score_tooling//cpp/libclang:libclang_toolchain_type",
+)
+
 # ============================================================================
 # Test Fixtures - Module Definitions
 # ============================================================================
@@ -126,15 +180,6 @@ sphinx_module(
     ],
 )
 
-# Test 2: Graphviz Rendering
-# Tests hermetic graphviz support via sphinx.ext.graphviz directive
-sphinx_module(
-    name = "graphviz_test_lib",
-    srcs = glob(["fixtures/graphviz_test/*.rst"]),
-    index = "fixtures/graphviz_test/index.rst",
-    sphinx = "@score_tooling//bazel/rules/rules_score:score_build",
-)
-
 # Test 3: SEooC (Safety Element out of Context) Module
 # Tests the score_component macro with S-CORE process artifacts
 
@@ -283,7 +328,7 @@ unit_design(
 unit(
     name = "test_unit",
     testonly = True,
-    scope = ["//bazel/rules/rules_score/test:mock_lib1"],
+    scope = ["//:mock_lib1"],
     tests = [":test_unit_tests"],
     unit_design = [":test_unit_design"],
     implementation = [
@@ -709,26 +754,11 @@ aous_rst_sphinx_test(
 requirements_rst_test_suite(name = "requirements_rst_tests")
 
 # ============================================================================
-# Image srcs Tests
+# Image srcs Tests (defined in sub-package to avoid workspace-root edge case)
 # ============================================================================
-
-# Fixture: feature_requirements with image_srcs
-feature_requirements(
-    name = "feat_req_with_image",
-    srcs = ["fixtures/seooc_test/feature_requirements.trlc"],
-    image_srcs = [
-        "fixtures/image_srcs/diagrams/arch.svg",
-        "fixtures/image_srcs/diagrams/arch.png",
-    ],
-    deps = [":asr_trlc"],
-)
-
-image_srcs_sphinx_sources_test(
-    name = "image_srcs_sphinx_sources_test",
-    target_under_test = ":feat_req_with_image",
-)
-
-requirements_image_test_suite(name = "requirements_image_tests")
+# feat_req_with_image and image_srcs_sphinx_sources_test live in
+# //fixtures/image_srcs so that ctx.label.package is non-empty and
+# subrule_trlc_image_stage can strip the prefix correctly.
 
 # ============================================================================
 # Combined Test Suite
@@ -745,7 +775,7 @@ requirements_image_test_suite(name = "requirements_image_tests")
 trlc_requirements(
     name = "safety_measures_fixtures",
     srcs = ["fixtures/seooc_test/safety_measures_fixtures.trlc"],
-    spec = ["//bazel/rules/rules_score/trlc/config:score_requirements_model"],
+    spec = ["@score_tooling//bazel/rules/rules_score/trlc/config:score_requirements_model"],
 )
 
 trlc_requirements_test(
@@ -757,14 +787,14 @@ py_test(
     name = "test_safety_analysis_tools",
     size = "small",
     srcs = ["test_safety_analysis_tools.py"],
-    deps = ["//bazel/rules/rules_score:safety_analysis_tools"],
+    deps = ["@score_tooling//bazel/rules/rules_score:safety_analysis_tools"],
 )
 
 py_test(
     name = "test_aou_forwarding_to_lobster",
     size = "small",
     srcs = ["test_aou_forwarding_to_lobster.py"],
-    deps = ["//bazel/rules/rules_score:aou_forwarding_to_lobster"],
+    deps = ["@score_tooling//bazel/rules/rules_score:aou_forwarding_to_lobster"],
 )
 
 py_test(
@@ -772,7 +802,7 @@ py_test(
     size = "small",
     srcs = ["rst_to_trlc_test.py"],
     main = "rst_to_trlc_test.py",
-    deps = ["//bazel/rules/rules_score:rst_to_trlc_lib"],
+    deps = ["@score_tooling//bazel/rules/rules_score:rst_to_trlc_lib"],
 )
 
 py_test(
@@ -787,27 +817,18 @@ py_test(
     deps = ["@trlc//tools/trlc_rst:trlc_rst_lib"],
 )
 
-py_test(
-    name = "test_graphviz_rendering",
-    size = "small",
-    srcs = ["graphviz_render_test.py"],
-    data = [":graphviz_test_lib"],
-    main = "graphviz_render_test.py",
-)
-
 # Combined test suite for all tests
 test_suite(
     name = "all_tests",
     tests = [
-        ":requirements_image_tests",
         ":requirements_rst_tests",
         ":seooc_tests",
         ":sphinx_module_tests",
         ":test_aou_forwarding_to_lobster",
-        ":test_graphviz_rendering",
         ":test_rst_to_trlc",
         ":test_safety_analysis_tools",
         ":test_trlc_rst_image_rendering",
         ":unit_component_tests",
+        "//fixtures/image_srcs:requirements_image_tests",
     ],
 )
diff --git a/bazel/rules/rules_score/test/MODULE.bazel b/bazel/rules/rules_score/test/MODULE.bazel
index da96457c..81e40c0c 100644
--- a/bazel/rules/rules_score/test/MODULE.bazel
+++ b/bazel/rules/rules_score/test/MODULE.bazel
@@ -55,6 +55,8 @@ pip.parse(
 use_repo(pip, "pip_tooling_test")
 
 bazel_dep(name = "score_docs_as_code", version = "3.0.1", dev_dependency = True)
+
+bazel_dep(name = "googletest", version = "1.17.0.bcr.2")
 # bazel_dep(name = "score_platform", version = "0.5.0")
 # bazel_dep(name = "score_process", version = "1.3.2")
 
@@ -68,16 +70,40 @@ register_toolchains(
     "//:score_toolchain",
 )
 
+###############################################################################
+# LLVM Toolchain (provides libclang for the score libclang toolchain below)
+#
+# As an integrating repository, this module supplies its own libclang/C++
+# toolchain instead of relying on score_tooling's (score_tooling declares LLVM
+# only as a dev dependency and does not register a libclang toolchain for
+# consumers).
+###############################################################################
+bazel_dep(name = "toolchains_llvm", version = "1.6.0")
+
+llvm = use_extension(
+    "@toolchains_llvm//toolchain/extensions:llvm.bzl",
+    "llvm",
+)
+llvm.toolchain(
+    cxx_standard = {"": "c++17"},
+    llvm_version = "19.1.7",
+)
+use_repo(llvm, "llvm_toolchain", "llvm_toolchain_llvm")
+
+register_toolchains(
+    "//:test_libclang_toolchain",
+)
+
 bazel_dep(name = "trlc", version = "0.0.0")
 git_override(
     module_name = "trlc",
-    commit = "7f06d0396fd0e5f02b657d25700775af5113b7e0",
+    commit = "c4c531b9d667085daa09dfc1590edacc314bfda4",
     remote = "https://github.com/bmw-software-engineering/trlc.git",
 )
 
 bazel_dep(name = "lobster", version = "0.0.0")
 git_override(
     module_name = "lobster",
-    commit = "56881461f9d3fde2918d1731aa5937aaf64cd67c",
+    commit = "2792e2daee2cf524fdc7b1545fd3537791ebc36c",
     remote = "https://github.com/bmw-software-engineering/lobster.git",
 )
diff --git a/bazel/rules/rules_score/test/fixtures/graphviz_test/index.rst b/bazel/rules/rules_score/test/fixtures/graphviz_test/index.rst
deleted file mode 100644
index cb44cddb..00000000
--- a/bazel/rules/rules_score/test/fixtures/graphviz_test/index.rst
+++ /dev/null
@@ -1,35 +0,0 @@
-..
-    # *******************************************************************************
-    # Copyright (c) 2026 Contributors to the Eclipse Foundation
-    #
-    # See the NOTICE file(s) distributed with this work for additional
-    # information regarding copyright ownership.
-    #
-    # This program and the accompanying materials are made available under the
-    # terms of the Apache License Version 2.0 which is available at
-    # https://www.apache.org/licenses/LICENSE-2.0
-    #
-    # SPDX-License-Identifier: Apache-2.0
-    # *******************************************************************************
-
-Graphviz Rendering Test
-=======================
-
-This document tests the ``sphinx.ext.graphviz`` directive to ensure hermetic graphviz
-integration is working correctly.
-
-Simple DAG
-----------
-
-.. graphviz::
-   :align: center
-
-   digraph {
-       A -> B;
-       A -> C;
-       B -> D;
-       C -> D;
-       label = "Simple DAG";
-   }
-
-This graphviz diagram should render as SVG in the produced HTML output.
diff --git a/bazel/rules/rules_score/test/fixtures/image_srcs/BUILD b/bazel/rules/rules_score/test/fixtures/image_srcs/BUILD
new file mode 100644
index 00000000..d3f9120f
--- /dev/null
+++ b/bazel/rules/rules_score/test/fixtures/image_srcs/BUILD
@@ -0,0 +1,47 @@
+# *******************************************************************************
+# Copyright (c) 2026 Contributors to the Eclipse Foundation
+#
+# See the NOTICE file(s) distributed with this work for additional
+# information regarding copyright ownership.
+#
+# This program and the accompanying materials are made available under the
+# terms of the Apache License Version 2.0 which is available at
+# https://www.apache.org/licenses/LICENSE-2.0
+#
+# SPDX-License-Identifier: Apache-2.0
+# *******************************************************************************
+
+# This sub-package exists so that ctx.label.package == "fixtures/image_srcs"
+# when feature_requirements stages image files.  subrule_trlc_image_stage
+# strips package_prefix from short_path to produce package-relative paths
+# (e.g. "diagrams/arch.png"); this only works when the package is not the
+# workspace root ("").
+
+load(
+    "@score_tooling//bazel/rules/rules_score:rules_score.bzl",
+    "feature_requirements",
+)
+load(
+    "//:requirements_image_test.bzl",
+    "image_srcs_sphinx_sources_test",
+    "requirements_image_test_suite",
+)
+
+package(default_visibility = ["//visibility:public"])
+
+feature_requirements(
+    name = "feat_req_with_image",
+    srcs = ["//:fixtures/seooc_test/feature_requirements.trlc"],
+    image_srcs = [
+        "diagrams/arch.svg",
+        "diagrams/arch.png",
+    ],
+    deps = ["//:asr_trlc"],
+)
+
+image_srcs_sphinx_sources_test(
+    name = "image_srcs_sphinx_sources_test",
+    target_under_test = ":feat_req_with_image",
+)
+
+requirements_image_test_suite(name = "requirements_image_tests")
diff --git a/bazel/rules/rules_score/test/graphviz_render_test.py b/bazel/rules/rules_score/test/graphviz_render_test.py
deleted file mode 100644
index 8a92641c..00000000
--- a/bazel/rules/rules_score/test/graphviz_render_test.py
+++ /dev/null
@@ -1,82 +0,0 @@
-# *******************************************************************************
-# Copyright (c) 2025 Contributors to the Eclipse Foundation
-#
-# See the NOTICE file(s) distributed with this work for additional
-# information regarding copyright ownership.
-#
-# This program and the accompanying materials are made available under the
-# terms of the Apache License Version 2.0 which is available at
-# https://www.apache.org/licenses/LICENSE-2.0
-#
-# SPDX-License-Identifier: Apache-2.0
-# *******************************************************************************
-"""Integration test for hermetic graphviz rendering in sphinx_module.
-
-Verifies that the sphinx.ext.graphviz extension successfully renders diagrams
-to SVG when using hermetic graphviz bundled via download_deb.
-"""
-
-import os
-import unittest
-
-
-def _runfile(*parts: str) -> str:
-    """Locate a file in the Bazel runfiles tree."""
-    srcdir = os.environ["TEST_SRCDIR"]
-    workspace = os.environ.get("TEST_WORKSPACE", "_main")
-    for candidate in [
-        os.path.join(srcdir, workspace, *parts),
-        os.path.join(srcdir, *parts),
-    ]:
-        if os.path.exists(candidate):
-            return candidate
-    raise FileNotFoundError(
-        f"Runfile not found: {os.path.join(*parts)}\n"
-        f"  Searched under TEST_SRCDIR={srcdir}"
-    )
-
-
-def _find_generated_html_root() -> str:
-    """Locate the generated HTML directory for graphviz_test_lib in runfiles.
-
-    Depending on Bazel/runfiles layout, the directory artifact may appear either
-    at ``.../graphviz_test_lib/html`` or at ``.../graphviz_test_lib``.
-    """
-    for parts in [
-        ("bazel/rules/rules_score/test/graphviz_test_lib/html",),
-        ("bazel/rules/rules_score/test/graphviz_test_lib",),
-    ]:
-        try:
-            root = _runfile(*parts)
-        except FileNotFoundError:
-            continue
-        if os.path.exists(os.path.join(root, "index.html")):
-            return root
-
-    raise FileNotFoundError(
-        "Unable to locate generated graphviz_test_lib HTML output in runfiles"
-    )
-
-
-class TestGraphvizRendering(unittest.TestCase):
-    """Verify that sphinx.ext.graphviz renders an SVG artifact."""
-
-    def test_graphviz_renders_svg(self):
-        """Test that graphviz output is rendered as SVG in generated HTML."""
-        html_dir = _find_generated_html_root()
-
-        svg_files = [
-            file_name
-            for _, _, files in os.walk(html_dir)
-            for file_name in files
-            if file_name.endswith(".svg")
-        ]
-
-        self.assertTrue(
-            svg_files,
-            "Generated HTML output should include at least one rendered graphviz SVG artifact",
-        )
-
-
-if __name__ == "__main__":
-    unittest.main()
diff --git a/bazel/rules/rules_score/test/trlc_rst_image_rendering_test.py b/bazel/rules/rules_score/test/trlc_rst_image_rendering_test.py
index 2f9d81bf..ee755455 100644
--- a/bazel/rules/rules_score/test/trlc_rst_image_rendering_test.py
+++ b/bazel/rules/rules_score/test/trlc_rst_image_rendering_test.py
@@ -48,19 +48,11 @@ def setUp(self):
         self._tmpdir = tempfile.mkdtemp()
         self._out = os.path.join(self._tmpdir, "output.rst")
         self._fixture_trlc = _runfile(
-            "bazel",
-            "rules",
-            "rules_score",
-            "test",
             "fixtures",
             "image_requirements",
             "image_requirements.trlc",
         )
         self._fixture_rsl = _runfile(
-            "bazel",
-            "rules",
-            "rules_score",
-            "test",
             "fixtures",
             "image_requirements",
             "schema.rsl",
diff --git a/cpp/libclang/BUILD b/cpp/libclang/BUILD
index 63d6a81b..fa3f8ef9 100644
--- a/cpp/libclang/BUILD
+++ b/cpp/libclang/BUILD
@@ -12,6 +12,7 @@
 # *******************************************************************************
 load("@bazel_skylib//rules:common_settings.bzl", "string_flag")
 load("@rules_rust//rust:defs.bzl", "rust_binary")
+load(":libclang_toolchain.bzl", "libclang_toolchain")
 
 string_flag(
     name = "log_level",
@@ -26,12 +27,37 @@ string_flag(
     visibility = ["//visibility:public"],
 )
 
+# Toolchain type that supplies libclang + the C++ include paths to the parser.
+# score_tooling does not register a libclang toolchain for consumers; each
+# integrating repository registers its own so it controls which libclang and
+# C++ standard library the parser resolves against.
+toolchain_type(
+    name = "libclang_toolchain_type",
+    visibility = ["//visibility:public"],
+)
+
+# Default libclang toolchain used by score_tooling's own build. It wraps the
+# LLVM installation that score_tooling declares as a dev dependency and is
+# registered via score_tooling's .bazelrc (--extra_toolchains), so it is NOT
+# inherited by repositories that depend on score_tooling.
+libclang_toolchain(
+    name = "score_tooling_libclang",
+    cxx_builtin_include = "@llvm_toolchain_llvm//:cxx_builtin_include",
+    extra_config_site = "@llvm_toolchain_llvm//:extra_config_site",
+    libclang = "@llvm_toolchain_llvm//:lib/libclang.so",
+    visibility = ["//visibility:public"],
+)
+
+toolchain(
+    name = "score_tooling_libclang_toolchain",
+    toolchain = ":score_tooling_libclang",
+    toolchain_type = ":libclang_toolchain_type",
+    visibility = ["//visibility:public"],
+)
+
 rust_binary(
     name = "clang_rs_parser",
     srcs = ["src/main.rs"],
-    data = [
-        "@llvm_toolchain_llvm//:libclang",
-    ],
     visibility = ["//visibility:public"],
     deps = [
         "//cpp/libclang/src/utils",
diff --git a/cpp/libclang/cpp_parser.bzl b/cpp/libclang/cpp_parser.bzl
index cbeab836..4e84ed95 100644
--- a/cpp/libclang/cpp_parser.bzl
+++ b/cpp/libclang/cpp_parser.bzl
@@ -14,6 +14,7 @@ load("@bazel_skylib//rules:common_settings.bzl", "BuildSettingInfo")
 load("@rules_cc//cc:find_cc_toolchain.bzl", "find_cc_toolchain", "use_cc_toolchain")
 load("@rules_cc//cc/common:cc_common.bzl", "cc_common")
 load("@rules_cc//cc/common:cc_info.bzl", "CcInfo")
+load(":libclang_toolchain.bzl", "LIBCLANG_TOOLCHAIN_TYPE")
 
 # Providers and aspects used to adapt C/C++ targets for the parser action.
 
@@ -145,26 +146,21 @@ def cpp_parser_action_internal_attrs():
             cfg = "exec",
             doc = "Internal libclang-based parser backend.",
         ),
-        "_libclang": attr.label(
-            allow_single_file = True,
-            default = "@llvm_toolchain_llvm//:lib/libclang.so",
-        ),
-        "_llvm_cxx_builtin_include": attr.label(
-            default = "@llvm_toolchain_llvm//:cxx_builtin_include",
-            doc = "LLVM toolchain filegroup containing the libc++ header directory (include/c++) " +
-                  "and the clang resource include directory (lib/clang/<version>/include).",
-        ),
-        "_llvm_extra_config_site": attr.label(
-            default = "@llvm_toolchain_llvm//:extra_config_site",
-            doc = "LLVM toolchain filegroup containing the arch-specific __config_site file " +
-                  "(include/<triple>/c++/v1/__config_site) used to locate the ABI include path.",
-        ),
         "_log_level": attr.label(
             default = Label("//cpp/libclang:log_level"),
             doc = "Build setting that controls clang_rs_parser log level.",
         ),
     }
 
+def cpp_parser_action_toolchains():
+    """Return toolchain types required by run_cpp_parser_action callers.
+
+    Rules that call run_cpp_parser_action must declare these toolchains so the
+    integrating repository's libclang toolchain is resolved for the action.
+    """
+
+    return [LIBCLANG_TOOLCHAIN_TYPE]
+
 # Parser action implementation.
 
 def _detect_standard_from_flags(ctx):
@@ -260,9 +256,6 @@ def run_cpp_parser_action(
         target,
         output_prefix,
         tool,
-        libclang,
-        llvm_cxx_builtin_include,
-        llvm_extra_config_site,
         log_level,
         extra_args = [],
         emit_debug_json = False):
@@ -270,9 +263,13 @@ def run_cpp_parser_action(
 
     The target must be analyzed with cpp_parser_target_aspects() before this
     helper is called. Use has_cpp_parser_inputs() when the caller accepts mixed
-    implementation target types.
+    implementation target types. The calling rule must declare the toolchains
+    returned by cpp_parser_action_toolchains().
     """
 
+    libclang_info = ctx.toolchains[LIBCLANG_TOOLCHAIN_TYPE].libclang_info
+    libclang = libclang_info.libclang
+
     class_fbs_output = ctx.actions.declare_file(
         "{}_{}".format(output_prefix, "class_diagram.fbs.bin"),
     )
@@ -299,8 +296,8 @@ def run_cpp_parser_action(
 
     target_compilation_flags_list = target[CompilationFlagsInfo].flags.to_list()
 
-    cxx_builtin_include_files = llvm_cxx_builtin_include.files.to_list()
-    extra_config_site_files = llvm_extra_config_site.files.to_list()
+    cxx_builtin_include_files = libclang_info.cxx_builtin_include.to_list()
+    extra_config_site_files = libclang_info.extra_config_site.to_list()
     llvm_include_args = _collect_required_llvm_include_args(cxx_builtin_include_files, extra_config_site_files)
 
     parser_extra_args = [
@@ -360,9 +357,6 @@ def _cpp_parser_impl(ctx):
         target = ctx.attr.target,
         output_prefix = ctx.label.name,
         tool = ctx.attr._tool,
-        libclang = ctx.file._libclang,
-        llvm_cxx_builtin_include = ctx.attr._llvm_cxx_builtin_include,
-        llvm_extra_config_site = ctx.attr._llvm_extra_config_site,
         log_level = ctx.attr._log_level[BuildSettingInfo].value,
         extra_args = ctx.attr.extra_args,
         emit_debug_json = ctx.attr.emit_debug_json,
@@ -403,6 +397,6 @@ _cpp_parser_attrs.update(cpp_parser_action_internal_attrs())
 cpp_parser = rule(
     implementation = _cpp_parser_impl,
     attrs = _cpp_parser_attrs,
-    toolchains = use_cc_toolchain(),
+    toolchains = cpp_parser_action_toolchains() + use_cc_toolchain(),
     fragments = ["cpp"],
 )
diff --git a/cpp/libclang/libclang_toolchain.bzl b/cpp/libclang/libclang_toolchain.bzl
new file mode 100644
index 00000000..b7de1528
--- /dev/null
+++ b/cpp/libclang/libclang_toolchain.bzl
@@ -0,0 +1,70 @@
+# *******************************************************************************
+# Copyright (c) 2026 Contributors to the Eclipse Foundation
+#
+# See the NOTICE file(s) distributed with this work for additional
+# information regarding copyright ownership.
+#
+# This program and the accompanying materials are made available under the
+# terms of the Apache License Version 2.0 which is available at
+# https://www.apache.org/licenses/LICENSE-2.0
+#
+# SPDX-License-Identifier: Apache-2.0
+# *******************************************************************************
+
+"""Toolchain definition that supplies libclang and the C++ include paths.
+
+score_tooling does not hard-code a specific LLVM installation for the libclang
+based C++ parser. Instead, each integrating repository registers its own
+`libclang_toolchain`, so it can decide which libclang/C++ standard library the
+parser resolves against.
+"""
+
+LIBCLANG_TOOLCHAIN_TYPE = "//cpp/libclang:libclang_toolchain_type"
+
+LibclangToolchainInfo = provider(
+    doc = "libclang shared library and C++ include directories for the parser.",
+    fields = {
+        "libclang": "libclang shared library File loaded by the parser at runtime.",
+        "cxx_builtin_include": "depset of files exposing the libc++ header directory " +
+                               "(include/c++) and the clang resource include directory " +
+                               "(lib/clang/<version>/include).",
+        "extra_config_site": "depset of files exposing the arch-specific __config_site " +
+                             "(include/<triple>/c++/v1/__config_site) used to locate the " +
+                             "ABI include path.",
+    },
+)
+
+def _libclang_toolchain_impl(ctx):
+    return [
+        platform_common.ToolchainInfo(
+            libclang_info = LibclangToolchainInfo(
+                libclang = ctx.file.libclang,
+                cxx_builtin_include = depset(ctx.files.cxx_builtin_include),
+                extra_config_site = depset(ctx.files.extra_config_site),
+            ),
+        ),
+    ]
+
+libclang_toolchain = rule(
+    implementation = _libclang_toolchain_impl,
+    doc = "Provides libclang and the C++ include directories required by the parser.",
+    attrs = {
+        "libclang": attr.label(
+            allow_single_file = True,
+            mandatory = True,
+            doc = "libclang shared library (e.g. lib/libclang.so).",
+        ),
+        "cxx_builtin_include": attr.label(
+            allow_files = True,
+            mandatory = True,
+            doc = "Filegroup with the libc++ header directory (include/c++) and the " +
+                  "clang resource include directory (lib/clang/<version>/include).",
+        ),
+        "extra_config_site": attr.label(
+            allow_files = True,
+            mandatory = True,
+            doc = "Filegroup with the arch-specific __config_site file " +
+                  "(include/<triple>/c++/v1/__config_site).",
+        ),
+    },
+)
diff --git a/python_basics/.bazelversion b/python_basics/.bazelversion
index 2bf50aaf..f9c71a52 100644
--- a/python_basics/.bazelversion
+++ b/python_basics/.bazelversion
@@ -1 +1 @@
-8.3.0
+8.5.1