diff --git a/.gitea/workflows/ci.yaml b/.gitea/workflows/ci.yaml
index 689a88a..96cc00f 100644
--- a/.gitea/workflows/ci.yaml
+++ b/.gitea/workflows/ci.yaml
@@ -14,7 +14,7 @@ jobs:
         run: |
           sudo apt-get update -y
           sudo apt-get install -y \
-            cmake doxygen gcc pkg-config \
+            cmake doxygen gcc gcovr pkg-config \
             libasound2-dev libfreetype-dev libharfbuzz-dev \
             libpng-dev libtiff-dev libwebp-dev \
             libudev-dev libx11-dev libxcursor-dev libxext-dev \
@@ -22,7 +22,9 @@ jobs:
             libxss-dev libxtst-dev
       - name: Configure and build
         run: |
-          cmake -S . -B build -DCMAKE_BUILD_TYPE=Debug
+          cmake -S . -B build \
+            -DCMAKE_BUILD_TYPE=Debug \
+            -DAKGL_COVERAGE=ON
           cmake --build build --parallel
       - name: Build API documentation
         run: doxygen Doxyfile
@@ -43,6 +45,13 @@ jobs:
           detailed_summary: true
           include_passed: true
           fail_on_failure: 'true'
+      - name: Upload coverage reports
+        if: always()
+        uses: actions/upload-artifact@v4
+        with:
+          name: code-coverage
+          path: build/coverage/
+          if-no-files-found: warn
 
   mutation_test:
     runs-on: ubuntu-latest
diff --git a/AGENTS.md b/AGENTS.md
index 91c8462..df3ee9f 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -28,6 +28,8 @@ Run one test while iterating, for example `ctest --test-dir build -R sprite --ou
 
 Run mutation testing with `cmake --build build --target mutation`. For a quick smoke run, use `scripts/mutation_test.py --target src/tilemap.c --max-mutants 10`; the harness mutates only a scratch copy and excludes the intentionally failing character test.
 
+Generate HTML and Cobertura coverage reports with `cmake -S . -B build-coverage -DAKGL_COVERAGE=ON -DCMAKE_BUILD_TYPE=Debug`, then build and run CTest. Reports are written to `build-coverage/coverage/`; this mode requires `gcovr` and GCC or Clang.
+
 ## Coding Style & Naming Conventions
 
 Follow the surrounding C style: braces on the next line for function bodies, spaces inside control-flow parentheses, and short, focused functions. Preserve the indentation of the file being edited; older files contain both spaces and tabs. Public symbols use the `akgl_` prefix, public types use `akgl_TypeName`, and constants/macros use `AKGL_UPPER_SNAKE_CASE`. Name matching header/source pairs by feature, such as `include/akgl/sprite.h` and `src/sprite.c`. No repository-wide formatter or linter is configured, so avoid unrelated formatting churn.
@@ -39,7 +41,7 @@ Follow the surrounding C style: braces on the next line for function bodies, spa
 
 ## Testing Guidelines
 
-Tests use simple executable return codes and are registered through CTest in `CMakeLists.txt`; there is no declared coverage threshold. Add focused tests as `tests/<feature>.c`, create a matching `test_<feature>` target, and register it with `add_test`. Put reusable fixtures in `tests/assets/` and keep paths compatible with tests launched from the build tree.
+Tests use simple executable return codes and are registered through CTest in `CMakeLists.txt`; there is no declared coverage threshold. Add focused tests as `tests/<feature>.c`, create a matching `test_<feature>` target, and register it with `add_test`. Put reusable fixtures in `tests/assets/` and keep paths compatible with tests launched from the build tree. Coverage mode wraps the suite in a CTest fixture so counters are reset before tests and reports are generated afterward.
 
 ## Commit & Pull Request Guidelines
 
diff --git a/CMakeLists.txt b/CMakeLists.txt
index f86c2ae..511fcce 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -2,6 +2,14 @@ cmake_minimum_required(VERSION 3.10)
 project(akgl LANGUAGES C)
 
 include(CTest)
+option(AKGL_COVERAGE "Instrument libakgl and generate coverage reports with CTest" OFF)
+
+if(AKGL_COVERAGE)
+  if(NOT CMAKE_C_COMPILER_ID MATCHES "GNU|Clang")
+    message(FATAL_ERROR "AKGL_COVERAGE requires GCC or Clang")
+  endif()
+  find_program(GCOVR_EXECUTABLE gcovr REQUIRED)
+endif()
 
 if(CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR)
 
@@ -141,6 +149,44 @@ target_include_directories(akgl PUBLIC
   deps/semver/
   )
 
+if(AKGL_COVERAGE)
+  target_compile_options(akgl PRIVATE --coverage -O0 -g)
+  target_link_options(akgl PRIVATE --coverage)
+
+  set(AKGL_COVERAGE_DIR "${CMAKE_CURRENT_BINARY_DIR}/coverage")
+  file(MAKE_DIRECTORY "${AKGL_COVERAGE_DIR}")
+
+  add_test(
+    NAME coverage_reset
+    COMMAND ${GCOVR_EXECUTABLE}
+            --root "${CMAKE_CURRENT_SOURCE_DIR}"
+            --object-directory "${CMAKE_CURRENT_BINARY_DIR}"
+            --delete
+  )
+  set_tests_properties(coverage_reset PROPERTIES FIXTURES_SETUP akgl_coverage)
+  set_tests_properties(
+    actor bitmasks character registry sprite staticstring tilemap util semver_unit
+    PROPERTIES FIXTURES_REQUIRED akgl_coverage
+  )
+
+  add_test(
+    NAME coverage_report
+    COMMAND ${GCOVR_EXECUTABLE}
+            --root "${CMAKE_CURRENT_SOURCE_DIR}"
+            --object-directory "${CMAKE_CURRENT_BINARY_DIR}"
+            --filter "${CMAKE_CURRENT_SOURCE_DIR}/src/"
+            --xml-pretty
+            --xml "${AKGL_COVERAGE_DIR}/coverage.xml"
+            --html-details "${AKGL_COVERAGE_DIR}/index.html"
+  )
+  set_tests_properties(
+    coverage_report
+    PROPERTIES
+      FIXTURES_CLEANUP akgl_coverage
+      WORKING_DIRECTORY "${CMAKE_CURRENT_BINARY_DIR}"
+  )
+endif()
+
 target_link_libraries(akgl
   PUBLIC
     SDL3::SDL3