diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 03fb02d..0954534 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -114,3 +114,45 @@ jobs:
 
       - name: Run PHPStan
         run: composer phpstan
+
+  coverage:
+    name: Coverage
+    runs-on: ubuntu-22.04
+    timeout-minutes: 15
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Setup PHP
+        uses: shivammathur/setup-php@v2
+        with:
+          php-version: '8.3'
+          coverage: xdebug
+          tools: composer:v2
+
+      - name: Setup Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: '22'
+
+      - name: Install Composer dependencies
+        run: composer update --no-interaction --prefer-dist --no-progress
+
+      - name: Install Node.js dependencies
+        run: npm install
+
+      - name: Run PHP coverage
+        run: composer coverage
+
+      - name: Run JavaScript coverage
+        run: npm run test:coverage
+
+      - name: Upload coverage reports
+        uses: actions/upload-artifact@v4
+        with:
+          name: coverage-reports
+          if-no-files-found: error
+          path: |
+            build/logs/phpunit-clover.xml
+            build/coverage/jest
diff --git a/.gitignore b/.gitignore
index b5e5e3b..e189899 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,5 +1,7 @@
 .idea
 .phpunit.cache/
+build/
+coverage/
 vendor
 composer.lock
 
diff --git a/AGENTS.md b/AGENTS.md
index 95fdc4e..a7ca0e3 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -20,6 +20,8 @@ Local path: `/Volumes/SRC/JsFormValidatorBundle`
 - The JavaScript job runs on Node `22` with PHP `8.3`.
 - The JavaScript job installs Cypress system dependencies, then runs `composer update`, `npm install`, and `npm test`.
 - The PHPStan job runs on PHP `8.3`, installs dependencies with `composer update`, warms the Symfony test cache, and runs `composer phpstan`.
+- The Coverage job runs on PHP `8.3` with Xdebug and Node `22`, then runs `composer coverage` and `npm run test:coverage`.
+- Coverage thresholds currently enforced by `tools/check-clover-coverage.php`: PHP line coverage at least `50%`, JavaScript line coverage at least `60%`.
 - The old `.travis.yml` file was removed.
 - `README.md` was updated to use a GitHub Actions badge and test instructions instead of Travis CI references.
 - `package.json` no longer advertises the old Travis CI badge in the package description.
@@ -28,7 +30,9 @@ Local path: `/Volumes/SRC/JsFormValidatorBundle`
 
 - `php /tmp/jsfv-composer.phar test` passes: `5 tests, 18 assertions`.
 - `php /tmp/jsfv-composer.phar phpstan` runs PHPStan with `phpstan.neon`.
+- `php /tmp/jsfv-composer.phar coverage` generates PHP Clover coverage and checks the `50%` line threshold.
 - `npm test` passes: Jest `197 tests`; Cypress e2e `16 tests`.
+- `npm run test:coverage` generates Jest coverage and checks the `60%` line threshold.
 - The local `composer` shim is broken with `Could not open input file: /Users/ton/bin/composer`, so use `/tmp/jsfv-composer.phar` locally if needed.
 
 ## GitHub Checks Note
diff --git a/README.md b/README.md
index efc30a4..97fca42 100644
--- a/README.md
+++ b/README.md
@@ -198,12 +198,24 @@ Run PHPStan static analysis:
 composer phpstan
 ```
 
+Run PHP coverage:
+
+```bash
+composer coverage
+```
+
 Run the JavaScript unit tests and Cypress browser smoke test:
 
 ```bash
 npm test
 ```
 
+Run JavaScript coverage:
+
+```bash
+npm run test:coverage
+```
+
 Useful local checks:
 
 ```bash
diff --git a/composer.json b/composer.json
index f9fa8c5..13571b9 100644
--- a/composer.json
+++ b/composer.json
@@ -78,6 +78,10 @@
     },
 
     "scripts": {
+        "coverage": [
+            "XDEBUG_MODE=coverage phpunit --coverage-clover build/logs/phpunit-clover.xml --coverage-text --only-summary-for-coverage-text",
+            "php tools/check-clover-coverage.php build/logs/phpunit-clover.xml 50 PHP"
+        ],
         "phpstan": [
             "APP_ENV=test APP_DEBUG=1 php Tests/app/bin/console cache:warmup --env=test",
             "phpstan analyse --memory-limit=1G"
diff --git a/package.json b/package.json
index dcb3263..2649972 100755
--- a/package.json
+++ b/package.json
@@ -5,6 +5,7 @@
   "scripts": {
     "test": "npm run test:unit && npm run test:e2e",
     "test:unit": "jest",
+    "test:coverage": "jest --coverage --coverageReporters=text-summary --coverageReporters=clover --coverageReporters=lcov --coverageDirectory=build/coverage/jest && php tools/check-clover-coverage.php build/coverage/jest/clover.xml 60 JavaScript",
     "test:e2e": "npm run test:e2e:build && start-server-and-test test:e2e:serve http://127.0.0.1:8000 test:e2e:run",
     "test:e2e:build": "php Tests/app/bin/console assets:install Tests/app/public --env=test && npm --prefix Tests/app install && npm --prefix Tests/app run build",
     "test:e2e:serve": "APP_ENV=test APP_DEBUG=1 php -S 127.0.0.1:8000 -t Tests/app/public Tests/app/public/index.php",
diff --git a/tools/check-clover-coverage.php b/tools/check-clover-coverage.php
new file mode 100644
index 0000000..4fe1446
--- /dev/null
+++ b/tools/check-clover-coverage.php
@@ -0,0 +1,45 @@
+<?php
+
+if (4 !== $argc) {
+    fwrite(STDERR, "Usage: php tools/check-clover-coverage.php <clover.xml> <min-percent> <label>\n");
+    exit(2);
+}
+
+$file = $argv[1];
+$minimum = (float) $argv[2];
+$label = $argv[3];
+
+if (!is_file($file)) {
+    fwrite(STDERR, sprintf("%s coverage report not found: %s\n", $label, $file));
+    exit(1);
+}
+
+$xml = simplexml_load_file($file);
+if (false === $xml || !isset($xml->project->metrics)) {
+    fwrite(STDERR, sprintf("%s coverage report is not valid Clover XML: %s\n", $label, $file));
+    exit(1);
+}
+
+$metrics = $xml->project->metrics;
+$statements = (int) $metrics['statements'];
+$coveredStatements = (int) $metrics['coveredstatements'];
+
+if (0 === $statements) {
+    fwrite(STDERR, sprintf("%s coverage report has no statements.\n", $label));
+    exit(1);
+}
+
+$coverage = $coveredStatements / $statements * 100;
+printf(
+    "%s line coverage: %.2f%% (%d/%d), minimum: %.2f%%\n",
+    $label,
+    $coverage,
+    $coveredStatements,
+    $statements,
+    $minimum
+);
+
+if ($coverage + 0.00001 < $minimum) {
+    fwrite(STDERR, sprintf("%s line coverage is below the required minimum.\n", $label));
+    exit(1);
+}