diff --git a/.github/workflows/presubmit.yaml b/.github/workflows/presubmit.yaml
index 9c37deef21d..a908025cdc5 100644
--- a/.github/workflows/presubmit.yaml
+++ b/.github/workflows/presubmit.yaml
@@ -15,9 +15,7 @@ jobs:
         uses: actions/setup-node@v6
         with:
           node-version: ${{ matrix.node-version }}
-      - uses: pnpm/action-setup@v4
-        with:
-          version: ^10.0.0
+      - uses: oven-sh/setup-bun@v2
       - run: node --version
       - run: ci/run_conditional_tests.sh
         name: Run unit tests
diff --git a/.github/workflows/windows-presubmit.yaml b/.github/workflows/windows-presubmit.yaml
index 624c0f32a7c..a24c82a14e7 100644
--- a/.github/workflows/windows-presubmit.yaml
+++ b/.github/workflows/windows-presubmit.yaml
@@ -15,9 +15,7 @@ jobs:
         uses: actions/setup-node@v6
         with:
           node-version: ${{ matrix.node-version }}
-      - uses: pnpm/action-setup@v4
-        with:
-          version: ^10.0.0
+      - uses: oven-sh/setup-bun@v2
       - run: node --version
       - run: bash ci/run_conditional_tests.sh
         name: Run windows unit tests
@@ -25,3 +23,5 @@ jobs:
         env:
           BUILD_TYPE: presubmit
           TEST_TYPE: units
+          SHELL: C:\Program Files\Git\bin\bash.exe
+          npm_config_script_shell: bash
diff --git a/ci/run_conditional_tests.sh b/ci/run_conditional_tests.sh
index 573a74e2c04..4862dcf3a02 100755
--- a/ci/run_conditional_tests.sh
+++ b/ci/run_conditional_tests.sh
@@ -30,6 +30,10 @@ fi
 # A script file for running the test in a sub project.
 test_script="${PROJECT_ROOT}/ci/run_single_test.sh"
 
+# Install all dependencies globally to give Bun the opportunity to deduplicate
+# dependencies.
+bun install --ignore-scripts
+
 
 if [ ${BUILD_TYPE} == "presubmit" ]; then
     # For presubmit build, we want to know the difference from the
diff --git a/ci/run_single_test.sh b/ci/run_single_test.sh
index 31ce0206111..10c66258930 100755
--- a/ci/run_single_test.sh
+++ b/ci/run_single_test.sh
@@ -39,30 +39,33 @@ if [ ${BUILD_TYPE} != "presubmit" ]; then
     export MOCHA_REPORTER=xunit
 fi
 
-# Install dependencies
-echo "pnpm install --ignore-scripts --engine-strict --prod; pnpm install"
-pnpm install --ignore-scripts --engine-strict --prod; pnpm install
-
+# Run post install scripts.
+# Of the available post-install scripts, our repo only uses "prepare".
+echo "run post install scripts . . ."
+# Run script only if its defined.
+jq -e '.scripts.prepare' package.json > /dev/null && npm run prepare
 
 retval=0
 
+# We use `npm run` here so that the test run respects the Node version
+# configured for this test run.
 set +e
 case ${TEST_TYPE} in
 lint)
-    pnpm prelint
-    pnpm lint
+    npm run prelint
+    npm run lint
     retval=$?
     ;;
 samples)
-    pnpm samples-test
+    npm run samples-test
     retval=$?
     ;;
 system)
-    pnpm system-test
+    npm run system-test
     retval=$?
     ;;
 units)
-    pnpm test
+    npm run test
     retval=$?
     ;;
 *)
diff --git a/package.json b/package.json
index 9fe35bf5b43..c8f9b0c591b 100644
--- a/package.json
+++ b/package.json
@@ -44,5 +44,10 @@
   },
   "engines": {
     "node": ">=18"
-  }
+  },
+  "workspaces": [
+    "packages/*",
+    "handwritten/*",
+    ".github/scripts/*"
+  ]
 }
\ No newline at end of file