diff --git a/.github/citools/python/python-lint-bandit b/.github/citools/python/python-lint-bandit
new file mode 100755
index 00000000..030c48a5
--- /dev/null
+++ b/.github/citools/python/python-lint-bandit
@@ -0,0 +1,31 @@
+#!/bin/bash
+#
+# .github/citools/python/python-lint-bandit
+#
+
+# shellcheck disable=SC1091
+source ../../.github/citools/includes/wrapper-library || exit
+
+declare -i retval=0
+
+main() {
+	printf "\nRunning Python Lint - Bandit\n\n"
+
+	show_tool_versions_python_short
+
+	print_ruler
+
+	run_command bandit --version
+
+	print_ruler
+
+	# shellcheck disable=SC2048,SC2068,SC2086
+	run_command bandit ${@:---verbose --recursive ./src}
+
+	print_ruler
+
+	echo Exit code: "${retval}"
+	return "${retval}"
+}
+
+time main "${@}"
diff --git a/.github/citools/python/python-lint-formatter b/.github/citools/python/python-lint-pylint
similarity index 56%
rename from .github/citools/python/python-lint-formatter
rename to .github/citools/python/python-lint-pylint
index 5d6f3e26..65f637cf 100755
--- a/.github/citools/python/python-lint-formatter
+++ b/.github/citools/python/python-lint-pylint
@@ -1,6 +1,6 @@
 #!/bin/bash
 #
-# .github/citools/python/python-lint-formatter
+# .github/citools/python/python-lint-pylint
 #
 
 # shellcheck disable=SC1091
@@ -9,13 +9,18 @@ source ../../.github/citools/includes/wrapper-library || exit
 declare -i retval=0
 
 main() {
-	printf "\nRunning Python Formatter\n\n"
+	printf "\nRunning Python Lint - PyLint\n\n"
 
 	show_tool_versions_python_short
 
 	print_ruler
 
-	run_command ruff .
+	run_command pylint --version
+
+	print_ruler
+
+	# shellcheck disable=SC2048,SC2068,SC2086
+	run_command pylint ${@:-./src}
 
 	print_ruler
 
diff --git a/.github/citools/python/python-lint-pyright b/.github/citools/python/python-lint-pyright
new file mode 100755
index 00000000..1b5ce2af
--- /dev/null
+++ b/.github/citools/python/python-lint-pyright
@@ -0,0 +1,31 @@
+#!/bin/bash
+#
+# .github/citools/python/python-lint-pyright
+#
+
+# shellcheck disable=SC1091
+source ../../.github/citools/includes/wrapper-library || exit
+
+declare -i retval=0
+
+main() {
+	printf "\nRunning Python Lint - PyRight\n\n"
+
+	show_tool_versions_python_short
+
+	print_ruler
+
+	run_command pyright --version
+
+	print_ruler
+
+	# shellcheck disable=SC2048,SC2068,SC2086
+	run_command pyright ${@:---stats ./src}
+
+	print_ruler
+
+	echo Exit code: "${retval}"
+	return "${retval}"
+}
+
+time main "${@}"
diff --git a/.github/citools/python/python-lint-refurb b/.github/citools/python/python-lint-refurb
new file mode 100755
index 00000000..08aa20d9
--- /dev/null
+++ b/.github/citools/python/python-lint-refurb
@@ -0,0 +1,31 @@
+#!/bin/bash
+#
+# .github/citools/python/python-lint-refurb
+#
+
+# shellcheck disable=SC1091
+source ../../.github/citools/includes/wrapper-library || exit
+
+declare -i retval=0
+
+main() {
+	printf "\nRunning Python Lint - Refurb\n\n"
+
+	show_tool_versions_python_short
+
+	print_ruler
+
+	run_command refurb --version
+
+	print_ruler
+
+	# shellcheck disable=SC2048,SC2068,SC2086
+	run_command refurb ${@:-./src}
+
+	print_ruler
+
+	echo Exit code: "${retval}"
+	return "${retval}"
+}
+
+time main "${@}"
diff --git a/.github/citools/python/python-lint-ruff b/.github/citools/python/python-lint-ruff
new file mode 100755
index 00000000..4546da01
--- /dev/null
+++ b/.github/citools/python/python-lint-ruff
@@ -0,0 +1,31 @@
+#!/bin/bash
+#
+# .github/citools/python/python-lint-ruff
+#
+
+# shellcheck disable=SC1091
+source ../../.github/citools/includes/wrapper-library || exit
+
+declare -i retval=0
+
+main() {
+	printf "\nRunning Python Lint - Ruff\n\n"
+
+	show_tool_versions_python_short
+
+	print_ruler
+
+	run_command ruff --version
+
+	print_ruler
+
+	# shellcheck disable=SC2048,SC2068,SC2086
+	run_command ruff ${@:-check --ignore E501 ./src}
+
+	print_ruler
+
+	echo Exit code: "${retval}"
+	return "${retval}"
+}
+
+time main "${@}"
diff --git a/.github/citools/python/python-test-with-coverage b/.github/citools/python/python-test-with-coverage
index 51c09c0c..6bb65cc5 100755
--- a/.github/citools/python/python-test-with-coverage
+++ b/.github/citools/python/python-test-with-coverage
@@ -19,17 +19,24 @@ main() {
 
 	print_ruler
 
-	run_command pytest --verbose --cov=. --cov-branch --cov-report={term-missing,xml:.coverage.xml} -p no:randomly || ((retval++))
+	run_command pytest --version
 
 	print_ruler
 
-	echo Running: coverage report --show-missing
-	coverage report --show-missing
+	export PYTHONPATH="./src"
+	printf "PYTHONPATH=\"%s\"\n" "${PYTHONPATH}"
 
 	print_ruler
 
-	echo Running: coverage annotate
-	coverage annotate
+	run_command pytest --verbose --cov=. --cov-branch --cov-report={term-missing,xml:.coverage.xml} -p no:randomly ./test || ((retval++))
+
+	print_ruler
+
+	run_command coverage report --show-missing
+
+	print_ruler
+
+	run_command coverage annotate
 
 	print_ruler
 
diff --git a/.github/citools/python/python-test-with-doctests b/.github/citools/python/python-test-with-doctests
new file mode 100755
index 00000000..17ee6562
--- /dev/null
+++ b/.github/citools/python/python-test-with-doctests
@@ -0,0 +1,32 @@
+#!/bin/bash
+#
+# .github/citools/python/python-test-doctest
+#
+
+# shellcheck disable=SC1091
+source ../../.github/citools/includes/wrapper-library || exit
+
+declare -i retval=0
+
+main() {
+	printf "\nRunning Python DocTests\n\n"
+
+	show_tool_versions_python_short
+
+	print_ruler
+
+	export PYTHONPATH="./src"
+	printf "PYTHONPATH=\"%s\"\n" "${PYTHONPATH}"
+
+	print_ruler
+
+	# shellcheck disable=SC2048,SC2068,SC2086
+	run_command python -m doctest ${@:--v ./src/*/*.py}
+
+	print_ruler
+
+	echo Exit code: "${retval}"
+	return "${retval}"
+}
+
+time main "${@}"
diff --git a/.github/workflows/python.yml b/.github/workflows/python.yml
index 0ed77165..758de9fa 100644
--- a/.github/workflows/python.yml
+++ b/.github/workflows/python.yml
@@ -2,9 +2,10 @@
 #
 # .github/workflows/python.yml
 #
-name: Python Workflow
+name: Python Workflow 3.0
 on:  # yamllint disable-line rule:truthy
   pull_request:
+  workflow_dispatch:
 
 defaults:
   run:
@@ -13,10 +14,15 @@ defaults:
 jobs:
   stage1:
     name: Change Check
-    runs-on: ubuntu-latest
+    runs-on: 'ubuntu-latest'
     outputs:
       docs_changed: ${{ steps.check_file_changed.outputs.docs_changed }}
+      matrix_exercise: ${{ steps.check_file_changed.outputs.matrix_exercise }}
+      exercise_count: ${{ steps.check_file_changed.outputs.exercise_count }}
     steps:
+      - name: Check GitHub Vars
+        id: github-vars
+        run: set | grep -e ^CI -e ^GITHUB_ -e ^RUNNER_
       - name: Checkout Repo
         id: checkout-repo
         uses: actions/checkout@v3
@@ -27,17 +33,56 @@ jobs:
       - name: Get Change List
         id: check_file_changed
         run: |
+          {
+            printf "Workflow: %s\n\n" "${GITHUB_WORKFLOW}"
+            printf "Runner: name[%s] arch[%s]\n" "${RUNNER_NAME}" "${RUNNER_ARCH}"
+            printf "Repo: %s\n" "${GITHUB_REPOSITORY}"
+            printf "User: %s\n" "${GITHUB_TRIGGERING_ACTOR}"
+            printf "\n"
+          } | tee -a "${GITHUB_STEP_SUMMARY}"
+
           # Diff HEAD with the previous commit then output to stdout.
-          printf "=== Which files changed? ===\n"
-          GIT_DIFF="$(git diff --name-only HEAD^ HEAD)"
-          printf "%s\n" "${GIT_DIFF}"
+          GIT_DIFF="$(git diff --name-only HEAD^ HEAD | tee /tmp/changed_files.txt)"
+          {
+            printf "=== Which files changed? ===\n"
+            printf "\`\`\`text\n"
+            printf "%s\n" "${GIT_DIFF}"
+            printf "\`\`\`\n"
+          } | tee -a "${GITHUB_STEP_SUMMARY}"
+          HAS_WF_DIFF=false
+          HAS_EX_DIFF=false
+          if printf "%s\n" "${GIT_DIFF}" | grep -E '^(.github/workflows/cpp.yml|.github/citools/cpp/)$'; then
+            HAS_WF_DIFF=true
+          fi
+          if printf "%s\n" "${GIT_DIFF}" | grep -E '^(cpp/.*[.](cpp|h|hpp)|cpp/.*/[Ma]akefile|cpp/.*/CMakeLists.txt)$'; then
+            HAS_EX_DIFF=true
+          fi
+          printf "\n"
+          printf "=== Did WF/CI change without exercise changes? ===\n"
+          CI_FORCE_FULL=false
+          if ${HAS_WF_DIFF} && ! ${HAS_EX_DIFF}; then
+            CI_FORCE_FULL=true
+            printf "%s\n" "${CI_FORCE_FULL}"
+          fi
+          printf "\n"
+
+          # Get changed exercise list.
+          if [[ ${GITHUB_EVENT_NAME} == pull_request ]] && ! ${CI_FORCE_FULL}; then
+            printf "Generating pull request changed exercise list.\n"
+            grep -E '^cpp/[-a-z0-9]+./.*$' /tmp/changed_files.txt | cut -f1,2 -d/ | sort -Vu | tee /tmp/exercises.txt || true
+          else
+            printf "Generating complete exercise list.\n"
+            find ./cpp/ -type d -print | grep -v -E '^[.]/cpp/(|[.].*)$' | sed -r -e 's:[.]/(cpp/[-a-z0-9]+)/?.*$:\1:g' | sort -Vu | tee /tmp/exercises.txt || true
+            HAS_DIFF=true
+          fi
           printf "\n"
 
           # Check if the files are present in the changed file list (added, modified, deleted) then output to stdout.
-          HAS_DIFF=false
+          HAS_DIFF="${HAS_DIFF:-false}"
           printf "=== Which Python files changed? ===\n"
           if printf "%s\n" "${GIT_DIFF}" | grep -E '^(python/.*[.]py|.github/workflows/python.yml)'; then
             HAS_DIFF=true
+            printf "%s\n" "${HAS_DIFF}"
           fi
           printf "\n"
 
@@ -46,71 +91,187 @@ jobs:
           printf "%s\n" "${HAS_DIFF}"
           printf "\n"
 
+          # Generate exercise job matrix from changed files list.
+          printf "=== Generating matrix exercise list. ===\n"
+          declare -i last=0
+          declare -i count=0
+          last=$(wc -l /tmp/exercises.txt | cut -f1 -d\ )
+          ((last -= 1)) || true
+          entries=""
+          while read -r line; do
+            if [[ ! ${count} -lt ${last} ]]; then
+              comma=""
+            else
+              comma=","
+            fi
+            printf -v entry "\"%s\"%s\n" "${line}" "${comma}"
+            ((count += 1))
+            entries+="${entry}"
+          done < <(sort -V /tmp/exercises.txt)
+          jq --sort-keys . >/tmp/exercises.json <<EOF
+            [ ${entries} ]
+          EOF
+          exercise_count="$(jq '. | length' /tmp/exercises.json)"
+          printf "%s=%s\n" "exercise_count" "${exercise_count}" | tee -a "${GITHUB_OUTPUT}"
+          matrix_exercise="$(jq --compact-output --sort-keys . /tmp/exercises.json)"
+          printf "%s=%s\n" "matrix_exercise" "${matrix_exercise}" | tee -a "${GITHUB_OUTPUT}"
+          printf "\n"
+          cat "${GITHUB_OUTPUT}"
+
+          # Don't run stage 2 if PR mode doesn't have testable changes.
+          if [[ ${GITHUB_EVENT_NAME} == pull_request ]] && [[ -z ${entries} ]]; then
+            printf "In PR mode with no testable changes, disabling stage 2.\n"
+            HAS_DIFF=false
+          fi
+
           # Set the output named "docs_changed"
           printf "%s=%s\n" "docs_changed" "${HAS_DIFF}" >> "${GITHUB_OUTPUT}"
+  check-matrix:
+    runs-on: ubuntu-latest
+    needs: stage1
+    steps:
+      - name: Install json2yaml
+        run: sudo npm install -g json2yaml
+      - name: Check matrix::exercises
+        run: |
+          exercise_count='${{ needs.stage1.outputs.exercise_count }}'
+          matrix_exercise='${{ needs.stage1.outputs.matrix_exercise }}'
+          {
+            printf "\`\`\`text\n"
+            printf "exercise_count=%s\n" "${exercise_count}"
+            printf "matrix_exercise=%s\n" "${matrix_exercise}"
+            printf "\`\`\`\n"
+            printf "json:\n"
+            printf "\`\`\`text\n"
+            printf "%s" "${matrix_exercise}" | jq .
+            printf "\`\`\`\n"
+          } | tee -a "${GITHUB_STEP_SUMMARY}"
+          {
+            printf "yaml:\n"
+            printf "\`\`\`text\n"
+            printf "{ \"matrix\": { \"exercise\": %s } }" "${matrix_exercise}" | json2yaml
+            printf "\`\`\`\n"
+          } | tee -a "${GITHUB_STEP_SUMMARY}"
   stage2:
     name: Python Checks
     strategy:
       matrix:
-        python-version: ['3.11', '3.12']
-        os: [ubuntu-latest]
-    runs-on: ${{ matrix.os }}
+        os: ["ubuntu-latest", "windows-latest", "macos-latest"]
+        exclude:
+          - os: "macos-latest"
+          - os: "windows-latest"
+        exercise: ${{fromJson(needs.stage1.outputs.matrix_exercise)}}
+    runs-on: "${{ matrix.os }}"
+    container:
+      image: vpayno/ci-generic-debian:latest
     needs: [stage1]
     if: needs.stage1.outputs.docs_changed == 'True'
     steps:
       - name: Checkout Repo
         id: checkout-repo
         uses: actions/checkout@v3
-      - name: Set up Python ${{ matrix.python-version }}
-        id: setup-python
-        uses: actions/setup-python@v3
-        with:
-          python-version: ${{ matrix.python-version }}
       - name: Show Python version
         id: python-version
         run: |
           python --version
-      - name: Install Python Tools
-        id: install-python-tools
-        run: |
-          python -m pip install --upgrade pip
+          pyenv --version
+          pip --version
       - name: CD to Python Dir
         id: cd-to-python-dir
         run: |
           pwd
           ls
-          cd ./python
+          cd "./${{ matrix.exercise }}"
           pwd
           ls
       - name: Analysing the code with pylint
         id: pylint
         run: |
-          pip install --upgrade pylint
-          cd ./python
-          ./for_each pylint ./src
+          pwd
+          cd "./${{ matrix.exercise }}"
+          pwd
+          ls
+          {
+            printf "pylint output\n\n"
+            printf "\`\`\`text\n"
+            ../../.github/citools/python/python-lint-pylint
+            printf "\`\`\`\n"
+          } | tee -a "${GITHUB_STEP_SUMMARY}"
       - name: Analysing the code with ruff
         id: ruff
         run: |
-          pip install --upgrade ruff
-          cd ./python
-          ./for_each ruff check --ignore E501 ./src
+          pwd
+          cd "./${{ matrix.exercise }}"
+          pwd
+          ls
+          {
+            printf "ruff output\n\n"
+            printf "\`\`\`text\n"
+            ../../.github/citools/python/python-lint-ruff
+            printf "\`\`\`\n"
+          } | tee -a "${GITHUB_STEP_SUMMARY}"
       - name: Analysing the code with pyright
         id: pyright
         run: |
-          pip install --upgrade pyright
-          cd ./python
-          ./for_each pyright --stats ./src || true
+          pwd
+          cd "./${{ matrix.exercise }}"
+          pwd
+          ls
+          {
+            printf "pyright output\n\n"
+            printf "\`\`\`text\n"
+            ../../.github/citools/python/python-lint-pyright
+            printf "\`\`\`\n"
+          } | tee -a "${GITHUB_STEP_SUMMARY}"
       - name: Analysing the code with bandit
         id: bandit
         run: |
-          pip install --upgrade bandit[toml]
-          cd ./python
-          ./for_each bandit --verbose --recursive ./src || true
+          pwd
+          cd "./${{ matrix.exercise }}"
+          pwd
+          ls
+          {
+            printf "bandit output\n\n"
+            printf "\`\`\`text\n"
+            ../../.github/citools/python/python-lint-bandit
+            printf "\`\`\`\n"
+          } | tee -a "${GITHUB_STEP_SUMMARY}"
+      - name: Analysing the code with refurb
+        id: refurb
+        run: |
+          pwd
+          cd "./${{ matrix.exercise }}"
+          pwd
+          ls
+          {
+            printf "bandit output\n\n"
+            printf "\`\`\`text\n"
+            ../../.github/citools/python/python-lint-refurb
+            printf "\`\`\`\n"
+          } | tee -a "${GITHUB_STEP_SUMMARY}"
+      - name: Testing with doctests
+        id: pytest-doctest-run
+        run: |-
+          pwd
+          cd "./${{ matrix.exercise }}"
+          pwd
+          ls
+          {
+            printf "doctests\n\n"
+            printf "\`\`\`text\n"
+            ../../.github/citools/python/python-test-with-doctests
+            printf "\`\`\`\n"
+          } | tee -a "${GITHUB_STEP_SUMMARY}"
       - name: Testing with pytest
-        id: pytest-test-run
+        id: pytest-pytest-run
         run: |-
-          sudo apt install libsqlite3-dev
-          pip install --upgrade db-sqlite3 pysqlite3
-          pip install --upgrade pytest coverage pytest-cov
-          cd ./python
-          PYTHONPATH="./src" ./for_each pytest --verbose --cov=. --cov-branch --cov-report={term-missing,xml:.coverage.xml} ./test
+          pwd
+          cd "./${{ matrix.exercise }}"
+          pwd
+          ls
+          {
+            printf "pytest with coverage output\n\n"
+            printf "\`\`\`text\n"
+            ../../.github/citools/python/python-test-with-coverage
+            printf "\`\`\`\n"
+          } | tee -a "${GITHUB_STEP_SUMMARY}"
diff --git a/python/run-tests b/python/run-tests
index fe89f3d8..a00bef36 100755
--- a/python/run-tests
+++ b/python/run-tests
@@ -16,64 +16,51 @@ main() {
 
 	# https://github.com/pylint-dev/pylint
 
-	echo Running: pylint ./src
-	time pylint ./src
+	echo Running: ../../.github/citools/python/python-lint-pylint
+	time ../../.github/citools/python/python-lint-pylint
 
 	print_ruler
 
 	# https://github.com/charliermarsh/ruff
 
-	echo Running: ruff check --ignore E501 ./src
-	time ruff check --ignore E501 ./src
+	echo Running: ../../.github/citools/python/python-lint-ruff
+	time ../../.github/citools/python/python-lint-ruff
 
 	print_ruler
 
 	# https://github.com/microsoft/pyright
 
-	echo Running: pyright --stats ./src
-	time pyright --stats ./src
+	echo Running: ../../.github/citools/python/python-lint-pyright
+	time ../../.github/citools/python/python-lint-pyright
 
 	print_ruler
 
 	# https://github.com/PyCQA/bandit
 
-	echo Running: bandit --verbose --recursive ./src
-	time bandit --verbose --recursive ./src
+	echo Running: ../../.github/citools/python/python-lint-bandit
+	time ../../.github/citools/python/python-lint-bandit
 
 	print_ruler
 
 	# https://github.com/dosisod/refurb
 
-	echo Running: refurb ./src
-	time refurb ./src
+	echo Running: ../../.github/citools/python/python-lint-refurb
+	time ../../.github/citools/python/python-lint-refurb
 
 	print_ruler
 
-	echo python -m doctest -v ./src/*/*py
-	time python -m doctest -v ./src/*/*py
-	printf "\n"
+	echo Running: ../../.github/citools/python/python-test-doctest
+	time ../../.github/citools/python/python-test-doctest
 
 	print_ruler
 
 	# https://github.com/pytest-dev/pytest
 
-	tail -v -n 1000 .coveragerc
-	printf "\n"
-
-	echo Running: PYTHONPATH="./src" pytest --verbose --cov=. --cov-branch --cov-report={term-missing,xml:.coverage.xml} -p no:randomly ./test
-	time { PYTHONPATH="./src" pytest --verbose --cov=. --cov-branch --cov-report={term-missing,xml:.coverage.xml} -p no:randomly ./test; }
-
-	print_ruler
-
-	echo Running: coverage report --show-missing
-	time coverage report --show-missing
+	echo Running: ../../.github/citools/python/python-test-with-coverage
+	time ../../.github/citools/python/python-test-with-coverage
 
 	print_ruler
 
-	echo coverage annotate
-	time coverage annotate
-	printf "\n"
-
 	echo tail -n 10000 './*,cover' '|' grep -E -C 3 "'^> def |^! '"
 	tail -n 10000 ./*,cover | grep -E -C 1 '^> def |^! '