diff --git a/.github/workflows/coding-standards.yml b/.github/workflows/coding-standards.yml
new file mode 100644
index 0000000..26873f8
--- /dev/null
+++ b/.github/workflows/coding-standards.yml
@@ -0,0 +1,85 @@
+name: PHP coding standards
+
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+    branches:
+      - main
+  workflow_dispatch:
+
+jobs:
+  # Runs the PHP coding standards checks.
+  #
+  # Violations are reported inline with annotations.
+  #
+  # Performs the following steps:
+  # - Checks out the repository.
+  # - Sets up PHP.
+  # - Configures caching for PHPCS scans.
+  # - Installs Composer dependencies.
+  # - Make Composer packages available globally.
+  # - Runs PHPCS on the full codebase (warnings excluded).
+  # - Generate a report for displaying issues as pull request annotations.
+  # - Runs PHPCS on the `tests` directory without (warnings included).
+  # - Generate a report for displaying `test` directory issues as pull request annotations.
+  # - Ensures version-controlled files are not modified or deleted.
+  phpcs:
+    name: Run coding standards checks
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+    timeout-minutes: 20
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # v4.1.1
+        with:
+          show-progress: ${{ runner.debug == '1' && 'true' || 'false' }}
+
+      - name: Set up PHP
+        uses: shivammathur/setup-php@c541c155eee45413f5b09a52248675b1a2575231 # v2.31.1
+        with:
+          coverage: none
+          tools: cs2pr
+
+      # This date is used to ensure that the PHPCS cache is cleared at least once every week.
+      # http://man7.org/linux/man-pages/man1/date.1.html
+      - name: "Get last Monday's date"
+        id: get-date
+        run: echo "date=$(/bin/date -u --date='last Mon' "+%F")" >> $GITHUB_OUTPUT
+
+      - name: Cache PHPCS scan cache
+        uses: actions/cache@3624ceb22c1c5a301c8db4169662070a689d9ea8 # v4.1.1
+        with:
+          path: |
+            .cache/phpcs-src.json
+            .cache/phpcs-tests.json
+          key: ${{ runner.os }}-date-${{ steps.get-date.outputs.date }}-php-${{ inputs.php-version }}-phpcs-cache-${{ hashFiles('**/composer.json', 'phpcs.xml.dist') }}
+
+      - name: Install Composer dependencies
+        uses: ramsey/composer-install@57532f8be5bda426838819c5ee9afb8af389d51a # v3.0.0
+
+      - name: Make Composer packages available globally
+        run: echo "${PWD}/vendor/bin" >> $GITHUB_PATH
+
+      - name: Run PHPCS on all files
+        id: phpcs-files
+        if: ${{ ! inputs.old-branch }}
+        run: phpcs -n --report-full --cache=./.cache/phpcs-src.json --report-checkstyle=./.cache/phpcs-report.xml
+
+      - name: Show PHPCS results in PR
+        if: ${{ always() && steps.phpcs-files.outcome == 'failure' }}
+        run: cs2pr ./.cache/phpcs-report.xml
+
+      - name: Check test suite files for warnings
+        id: phpcs-tests
+        run: phpcs tests --report-full --cache=./.cache/phpcs-tests.json --report-checkstyle=./.cache/phpcs-tests-report.xml
+
+      - name: Show test suite scan results in PR
+        if: ${{ always() && steps.phpcs-tests.outcome == 'failure' }}
+        run: cs2pr ./.cache/phpcs-tests-report.xml
+
+      - name: Ensure version-controlled files are not modified during the tests
+        run: git diff --exit-code