diff --git a/.github/workflows/cpp-kowalski-test.yml b/.github/workflows/cpp-kowalski-test.yml
new file mode 100644
index 0000000..f1aa8fb
--- /dev/null
+++ b/.github/workflows/cpp-kowalski-test.yml
@@ -0,0 +1,50 @@
+name: cpp-kowalski-test
+
+on:
+  push:
+    branches: [main]
+    paths: ['cpp/kowalski/**']
+  pull_request:
+    branches: ['**']
+    paths: ['cpp/kowalski/**']
+
+jobs:
+  cpp-kowalski-test:
+    runs-on: ubuntu-latest
+
+    defaults:
+      run:
+        working-directory: cpp/kowalski
+
+    steps:
+    - name: checkout code
+      uses: actions/checkout@v6
+      with:
+        fetch-depth: 0
+
+    - name: Setup Cpp
+      uses: aminya/setup-cpp@v1
+      with:
+        compiler: llvm
+        vcvarsall: true
+        clangtidy: true
+        clangformat: true
+        cmake: true
+        ninja: true
+
+    - name: configure
+      run: cmake -S . -B ./build -DCMAKE_EXPORT_COMPILE_COMMANDS=ON
+
+    - name: build
+      run: cmake --build ./build
+
+    - name: test
+      run: ctest --test-dir ./build --output-on-failure
+
+    - name: lint
+      run: |
+        find . -name '*.cc' -not -path './build/*' | xargs clang-tidy -p build/
+
+    - name: format check
+      run: |
+        find . \( -name '*.cc' -o -name '*.h' \) -not -path './build/*' | xargs clang-format --dry-run --Werror
diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
new file mode 100644
index 0000000..9d5d29e
--- /dev/null
+++ b/.pre-commit-config.yaml
@@ -0,0 +1,8 @@
+repos:
+  - repo: https://github.com/pocc/pre-commit-hooks
+    rev: v1.3.5
+    hooks:
+      - id: clang-tidy
+        args: [-p=cpp/kowalski/build]
+      - id: clang-format
+        args: [-i]
diff --git a/src/cpp/README.md b/cpp/README.md
similarity index 100%
rename from src/cpp/README.md
rename to cpp/README.md
diff --git a/cpp/kowalski/.clang-tidy b/cpp/kowalski/.clang-tidy
new file mode 100644
index 0000000..74b8e6e
--- /dev/null
+++ b/cpp/kowalski/.clang-tidy
@@ -0,0 +1,15 @@
+Checks: >
+  bugprone-*,
+  clang-analyzer-*,
+  cppcoreguidelines-*,
+  modernize-*,
+  performance-*,
+  portability-*,
+  readability-*,
+  -modernize-use-trailing-return-type,
+  -readability-magic-numbers,
+  -cppcoreguidelines-avoid-magic-numbers
+
+WarningsAsErrors: ''
+HeaderFilterRegex: '.*'
+FormatStyle: file
diff --git a/cpp/kowalski/CMakeLists.txt b/cpp/kowalski/CMakeLists.txt
new file mode 100644
index 0000000..365a7e8
--- /dev/null
+++ b/cpp/kowalski/CMakeLists.txt
@@ -0,0 +1,37 @@
+cmake_minimum_required(VERSION 3.23)
+
+set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
+
+project(entropylex-kowalski LANGUAGES CXX)
+
+set(CMAKE_CXX_STANDARD_REQUIRED ON)
+set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/bin)
+set(CMAKE_LIBRARY_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/lib)
+set(CMAKE_ARCHIVE_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/lib)
+
+
+include(FetchContent)
+
+FetchContent_Declare(
+  googletest
+  URL https://github.com/google/googletest/archive/03597a01ee50ed33e9dfd640b249b4be3799d395.zip
+)
+
+# For Windows: Prevent overriding the parent project's compiler/linker settings
+set(gtest_force_shared_crt ON CACHE BOOL "" FORCE)
+FetchContent_MakeAvailable(googletest)
+enable_testing()
+
+add_executable(main.test tests/main.test.cc)
+target_link_libraries(
+    main.test
+    GTest::gtest_main
+)
+
+include(GoogleTest)
+gtest_discover_tests(main.test)
+
+add_executable(entropylex
+  main.cc
+  entropylex8.h
+)
diff --git a/cpp/kowalski/entropylex8.h b/cpp/kowalski/entropylex8.h
new file mode 100644
index 0000000..36e795c
--- /dev/null
+++ b/cpp/kowalski/entropylex8.h
@@ -0,0 +1,11 @@
+#ifndef ENTROPYLEX8_H_
+#define ENTROPYLEX8_H_
+#include <array>
+#include <string>
+
+struct EntropyLex8 {
+public:
+  std::array<std::string, 256> lookup_;
+};
+
+#endif // ENTROPYLEX8_H_
diff --git a/cpp/kowalski/main.cc b/cpp/kowalski/main.cc
new file mode 100644
index 0000000..eb79522
--- /dev/null
+++ b/cpp/kowalski/main.cc
@@ -0,0 +1,7 @@
+#include "entropylex8.h"
+#include <iostream>
+
+int main() {
+  std::cout << "EntropyLex starting...\n";
+  return 0;
+}
diff --git a/cpp/kowalski/setup.md b/cpp/kowalski/setup.md
new file mode 100644
index 0000000..8f104f0
--- /dev/null
+++ b/cpp/kowalski/setup.md
@@ -0,0 +1,40 @@
+# Setup
+
+## Build & Test
+
+```bash
+cmake -S . -B ./build -DCMAKE_EXPORT_COMPILE_COMMANDS=ON
+cmake --build ./build
+ctest --test-dir ./build --output-on-failure
+```
+
+## Lint & Format
+
+Requires `compile_commands.json` (generated above).
+
+```bash
+# lint
+find . -name '*.cc' -not -path './build/*' | xargs clang-tidy -p build/
+
+# format check
+find . \( -name '*.cc' -o -name '*.h' \) -not -path './build/*' | xargs clang-format --dry-run --Werror
+
+# format fix
+find . \( -name '*.cc' -o -name '*.h' \) -not -path './build/*' | xargs clang-format -i
+```
+
+## Pre-commit Hook
+
+```bash
+# requires python installed
+pip install pre-commit
+pre-commit install
+```
+
+Runs clang-tidy/clang-format on staged files at commit time. Build `./build` at least once first so `compile_commands.json` exists.
+
+Run against all files manually:
+```bash
+pre-commit run --all-files
+```
+
diff --git a/cpp/kowalski/tests/main.test.cc b/cpp/kowalski/tests/main.test.cc
new file mode 100644
index 0000000..0fb924e
--- /dev/null
+++ b/cpp/kowalski/tests/main.test.cc
@@ -0,0 +1,14 @@
+#ifndef CPP_KOWALSKI_TESTS_MAIN_TEST_CC_
+#define CPP_KOWALSKI_TESTS_MAIN_TEST_CC_
+
+#include <gtest/gtest.h>
+
+// Demonstrate some basic assertions.
+TEST(HelloTest, BasicAssertions) {
+  // Expect two strings not to be equal.
+  EXPECT_STRNE("hello", "world");
+  // Expect equality.
+  EXPECT_EQ(7 * 6, 42);
+}
+
+#endif // CPP_KOWALSKI_TESTS_MAIN_TEST_CC_