diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 16553b3ac..28e7f9f2c 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -650,8 +650,6 @@ jobs:
     runs-on: windows-latest
 
     steps:
-      - uses: actions/checkout@v4
-
       - name: Setup MSYS2 environment
         uses: msys2/setup-msys2@v2
         with:
@@ -660,34 +658,86 @@ jobs:
           install: git python
           pacboy: gcc:p cmake:p ninja:p
 
-      - name: Fetch Boost.CI
-        uses: actions/checkout@v4
-        with:
-          repository: boostorg/boost-ci
-          ref: master
-          path: boost-ci-cloned
-      - name: Get CI scripts folder
-        run: |
-            # Copy ci folder if not testing Boost.CI
-            [[ "$GITHUB_REPOSITORY" =~ "boost-ci" ]] || cp -r boost-ci-cloned/ci .
-            rm -rf boost-ci-cloned
-
       - name: Setup Boost
-        env:
-          B2_COMPILER: ${{matrix.compiler}}
-          B2_CXXSTD: ${{matrix.cxxstd}}
-          B2_SANITIZE: ${{matrix.sanitize}}
-          B2_STDLIB: ${{matrix.stdlib}}
-        run: ci/github/install.sh
+        run: |
+            echo GITHUB_REPOSITORY: $GITHUB_REPOSITORY
+            LIBRARY=${GITHUB_REPOSITORY#*/}
+            echo LIBRARY: $LIBRARY
+            echo "LIBRARY=$LIBRARY" >> $GITHUB_ENV
+            echo GITHUB_BASE_REF: $GITHUB_BASE_REF
+            echo GITHUB_REF: $GITHUB_REF
+            REF=${GITHUB_BASE_REF:-$GITHUB_REF}
+            REF=${REF#refs/heads/}
+            echo REF: $REF
+            BOOST_BRANCH=develop && [ "$REF" = "master" ] && BOOST_BRANCH=master || true
+            echo BOOST_BRANCH: $BOOST_BRANCH
+            BUILD_JOBS=$((nproc || sysctl -n hw.ncpu) 2> /dev/null)
+            echo "BUILD_JOBS=$BUILD_JOBS" >> $GITHUB_ENV
+            echo "CMAKE_BUILD_PARALLEL_LEVEL=$BUILD_JOBS" >> $GITHUB_ENV
+            mkdir -p snapshot
+            cd snapshot
+            echo "Downloading library snapshot: https://github.com/${GITHUB_REPOSITORY}/archive/${GITHUB_SHA}.tar.gz"
+            curl -L --retry "$NET_RETRY_COUNT" -o "${LIBRARY}-${GITHUB_SHA}.tar.gz" "https://github.com/${GITHUB_REPOSITORY}/archive/${GITHUB_SHA}.tar.gz"
+            tar -xf "${LIBRARY}-${GITHUB_SHA}.tar.gz"
+            if [ ! -d "${LIBRARY}-${GITHUB_SHA}" ]
+            then
+                echo "Library snapshot does not contain the library directory ${LIBRARY}-${GITHUB_SHA}:"
+                ls -la
+                exit 1
+            fi
+            rm -f "${LIBRARY}-${GITHUB_SHA}.tar.gz"
+            cd ..
+            git clone -b "$BOOST_BRANCH" --depth 1 "https://github.com/boostorg/boost.git" "boost-root"
+            cd boost-root
+            mkdir -p libs
+            rm -rf "libs/$LIBRARY"
+            mv -f "../snapshot/${LIBRARY}-${GITHUB_SHA}" "libs/$LIBRARY"
+            rm -rf "../snapshot"
+            git submodule update --init tools/boostdep
+            python tools/boostdep/depinst/depinst.py --git_args "--jobs $GIT_FETCH_JOBS" --include example "$LIBRARY"
+            ./bootstrap.sh
+            ./b2 headers
+            echo -n "using ${{matrix.toolset}} : : ${{matrix.compiler}} ;" > ~/user-config.jam
 
       - name: Run tests
-        run: ci/build.sh
+        run: |
+            cd boost-root
+            export BOOST_FILESYSTEM_TEST_WITH_EXAMPLES=1
+            B2_ARGS=("-j" "$BUILD_JOBS" "toolset=${{matrix.toolset}}" "cxxstd=${{matrix.cxxstd}}")
+            if [ -n "${{matrix.build_variant}}" ]
+            then
+                B2_ARGS+=("variant=${{matrix.build_variant}}")
+            else
+                B2_ARGS+=("variant=$DEFAULT_BUILD_VARIANT")
+            fi
+            if [ -n "${{matrix.threading}}" ]
+            then
+                B2_ARGS+=("threading=${{matrix.threading}}")
+            fi
+            if [ -n "${{matrix.ubsan}}" ]
+            then
+                export UBSAN_OPTIONS="print_stacktrace=1"
+                B2_ARGS+=("cxxflags=-fsanitize=undefined -fno-sanitize-recover=undefined" "linkflags=-fsanitize=undefined -fuse-ld=gold" "define=UBSAN=1" "debug-symbols=on" "visibility=global")
+            fi
+            if [ -n "${{matrix.cxxflags}}" ]
+            then
+                B2_ARGS+=("cxxflags=${{matrix.cxxflags}}")
+            fi
+            if [ -n "${{matrix.linkflags}}" ]
+            then
+                B2_ARGS+=("linkflags=${{matrix.linkflags}}")
+            fi
+            B2_ARGS+=("libs/$LIBRARY/test")
+            ./b2 "${B2_ARGS[@]}"
 
       # Run also the CMake tests to avoid having to setup another matrix for CMake on MSYS
       - name: Run CMake tests
         run: |
-            cd "$BOOST_ROOT"
-            mkdir __build_cmake_test__ && cd __build_cmake_test__
-            cmake -G Ninja -DCMAKE_BUILD_TYPE=Debug -DBOOST_INCLUDE_LIBRARIES=$SELF -DBUILD_SHARED_LIBS=ON -DBUILD_TESTING=ON -DBoost_VERBOSE=ON ..
-            cmake --build . --target tests --config Debug -j$B2_JOBS
-            ctest --output-on-failure --build-config Debug
+            [ ! -d boost-root ] || cd boost-root
+            mkdir __build_static__ && cd __build_static__
+            cmake -DBUILD_SHARED_LIBS=OFF ../libs/$LIBRARY/test/test_cmake
+            cmake --build . --target boost_${LIBRARY}_cmake_self_test -j $BUILD_JOBS
+            cd ..
+            mkdir __build_shared__ && cd __build_shared__
+            cmake -DBUILD_SHARED_LIBS=ON ../libs/$LIBRARY/test/test_cmake
+            cmake --build . --target boost_${LIBRARY}_cmake_self_test -j $BUILD_JOBS