diff --git a/CRM/Core/Permission.php b/CRM/Core/Permission.php
index 5166b65466ae..2ad9e9977e06 100644
--- a/CRM/Core/Permission.php
+++ b/CRM/Core/Permission.php
@@ -841,6 +841,10 @@ public static function getCorePermissions() {
         $prefix . ts('administer payment processors'),
         ts('Add, Update, or Disable Payment Processors'),
       ],
+      'render templates' => [
+        $prefix . ts('render templates'),
+        ts('Render open-ended template content. (Additional constraints may apply to autoloaded records and specific notations.)'),
+      ],
       'edit message templates' => [
         $prefix . ts('edit message templates'),
       ],
diff --git a/Civi/Api4/Action/ExampleData/Get.php b/Civi/Api4/Action/ExampleData/Get.php
new file mode 100644
index 000000000000..9f91c82221f5
--- /dev/null
+++ b/Civi/Api4/Action/ExampleData/Get.php
@@ -0,0 +1,58 @@
+<?php
+
+/*
+ +--------------------------------------------------------------------+
+ | Copyright CiviCRM LLC. All rights reserved.                        |
+ |                                                                    |
+ | This work is published under the GNU AGPLv3 license with some      |
+ | permitted exceptions and without any warranty. For full license    |
+ | and copyright information, see https://civicrm.org/licensing       |
+ +--------------------------------------------------------------------+
+ */
+
+namespace Civi\Api4\Action\ExampleData;
+
+use Civi\Api4\Generic\BasicGetAction;
+use Civi\Api4\Generic\Result;
+use Civi\Test\ExampleDataLoader;
+
+/**
+ * Get a list of example data-sets.
+ *
+ * Examples are generated by scanning `*.ex.php` files. The scanner caches
+ * metadata fields (`name`, `title`, `tags`, `file`) to avoid extraneous scanning, but
+ * substantive fields (`data`) are computed as-needed.
+ *
+ * FIXME: When we have an update for dev-docs, include a `@link` here.
+ */
+class Get extends BasicGetAction {
+
+  public function _run(Result $result) {
+    if ($this->select !== [] && !in_array('name', $this->select)) {
+      $this->select[] = 'name';
+    }
+    parent::_run($result);
+  }
+
+  protected function getRecords() {
+    return \Civi\Test::examples()->getMetas();
+  }
+
+  protected function selectArray($values) {
+    $result = parent::selectArray($values);
+
+    $heavyFields = array_intersect(
+      explode(',', ExampleDataLoader::HEAVY_FIELDS),
+      $this->select ?: []
+    );
+    if (!empty($heavyFields)) {
+      foreach ($result as &$item) {
+        $heavy = \Civi\Test::examples()->getFull($item['name']);
+        $item = array_merge($item, \CRM_Utils_Array::subset($heavy, $heavyFields));
+      }
+    }
+
+    return $result;
+  }
+
+}
diff --git a/Civi/Api4/Action/WorkflowMessage/GetTemplateFields.php b/Civi/Api4/Action/WorkflowMessage/GetTemplateFields.php
new file mode 100644
index 000000000000..bef1735e03d5
--- /dev/null
+++ b/Civi/Api4/Action/WorkflowMessage/GetTemplateFields.php
@@ -0,0 +1,69 @@
+<?php
+
+namespace Civi\Api4\Action\WorkflowMessage;
+
+/**
+ * Class GetTemplateFields
+ * @package Civi\Api4\Action\WorkflowMessage
+ *
+ * @method $this setWorkflow(string $workflow)
+ * @method string getWorkflow()
+ * @method $this setFormat(string $workflow)
+ * @method string getFormat()
+ */
+class GetTemplateFields extends \Civi\Api4\Generic\BasicGetAction {
+
+  /**
+   * @var string
+   * @required
+   */
+  public $workflow;
+
+  /**
+   * Controls the return format.
+   *  - 'metadata': Return the fields as an array of metadata
+   *  - 'example': Return the fields as an example record (a basis for passing into Render::$values).
+   *
+   * @var string
+   * @options metadata,example
+   */
+  protected $format = 'metadata';
+
+  protected function getRecords() {
+    $item = \Civi\WorkflowMessage\WorkflowMessage::create($this->workflow);
+    /** @var \Civi\WorkflowMessage\FieldSpec[] $fields */
+    $fields = $item->getFields();
+    $array = [];
+    $genericExamples = [
+      'string[]' => ['example-string1', 'example-string2...'],
+      'string' => 'example-string',
+      'int[]' => [1, 2, 3],
+      'int' => 123,
+      'double[]' => [1.23, 4.56],
+      'double' => 1.23,
+      'array' => [],
+    ];
+
+    switch ($this->format) {
+      case 'metadata':
+        foreach ($fields as $name => $field) {
+          $array[$name] = $field->toArray();
+        }
+        return $array;
+
+      case 'example':
+        foreach ($fields as $name => $field) {
+          $array[$name] = NULL;
+          foreach (array_intersect(array_keys($genericExamples), $field->getType()) as $ex) {
+            $array[$name] = $genericExamples[$ex];
+          }
+        }
+        ksort($array);
+        return [$array];
+
+      default:
+        throw new \RuntimeException("Unrecognized format");
+    }
+  }
+
+}
diff --git a/Civi/Api4/Action/WorkflowMessage/Render.php b/Civi/Api4/Action/WorkflowMessage/Render.php
new file mode 100644
index 000000000000..86611072b9f7
--- /dev/null
+++ b/Civi/Api4/Action/WorkflowMessage/Render.php
@@ -0,0 +1,168 @@
+<?php
+
+/*
+ +--------------------------------------------------------------------+
+ | Copyright CiviCRM LLC. All rights reserved.                        |
+ |                                                                    |
+ | This work is published under the GNU AGPLv3 license with some      |
+ | permitted exceptions and without any warranty. For full license    |
+ | and copyright information, see https://civicrm.org/licensing       |
+ +--------------------------------------------------------------------+
+ */
+
+namespace Civi\Api4\Action\WorkflowMessage;
+
+use Civi\Api4\Event\ValidateValuesEvent;
+use Civi\WorkflowMessage\WorkflowMessage;
+
+/**
+ * Render a message.
+ *
+ * @method $this setValues(array $rows) Set the list of records to be rendered.
+ * @method array getValues()
+ * @method $this setMessageTemplate(array|null $fragments) Set of messages to be rendered.
+ * @method array|null getMessageTemplate()
+ * @method $this setMessageTemplateId(int|null $id) Set of messages to be rendered.
+ * @method int|null getMessageTemplateId()
+ * @method $this setWorkflow(string $workflow)
+ * @method string getWorkflow()
+ * @method $this setErrorLevel(string $workflow)
+ * @method string getErrorLevel()
+ */
+class Render extends \Civi\Api4\Generic\AbstractAction {
+
+  /**
+   * Abort if the validator finds any issues at this error level.
+   *
+   * @var string
+   * @options error,warning,info
+   */
+  protected $errorLevel = 'error';
+
+  /**
+   * Symbolic name of the workflow step for which we need a message.
+   * @var string
+   * @required
+   */
+  protected $workflow;
+
+  /**
+   * @var array
+   */
+  protected $values = [];
+
+  /**
+   * Load and render a specific message template (by ID).
+   *
+   * @var int|null
+   */
+  protected $messageTemplateId;
+
+  /**
+   * Use a draft message template.
+   *
+   * @var array|null
+   *   - `subject`: Message template (eg `Hello {contact.first_name}!`)
+   *   - `text`: Message template (eg `Hello {contact.first_name}!`)
+   *   - `html`: Message template (eg `<p>Hello {contact.first_name}!</p>`)
+   */
+  protected $messageTemplate;
+
+  /**
+   * @var \Civi\WorkflowMessage\WorkflowMessageInterface
+   */
+  protected $_model;
+
+  public function _run(\Civi\Api4\Generic\Result $result) {
+    $this->validateValues();
+
+    $r = \CRM_Core_BAO_MessageTemplate::renderTemplate([
+      'model' => $this->_model,
+      'messageTemplate' => $this->getMessageTemplate(),
+      'messageTemplateId' => $this->getMessageTemplateId(),
+    ]);
+
+    $result[] = \CRM_Utils_Array::subset($r, ['subject', 'html', 'text']);
+  }
+
+  /**
+   * The token-processor supports a range of context parameters. We enforce different security rules for each kind of input.
+   *
+   * Broadly, this distinguishes between a few values:
+   * - Autoloaded data (e.g. 'contactId', 'activityId'). We need to ensure that the specific records are visible and extant.
+   * - Inputted data (e.g. 'contact'). We merely ensure that these are type-correct.
+   * - Prohibited/extended options, e.g. 'smarty'
+   */
+  protected function validateValues() {
+    $rows = [$this->getValues()];
+    $e = new ValidateValuesEvent($this, $rows, new \CRM_Utils_LazyArray(function () use ($rows) {
+      return array_map(
+        function ($row) {
+          return ['old' => NULL, 'new' => $row];
+        },
+        $rows
+      );
+    }));
+    $this->onValidateValues($e);
+    \Civi::dispatcher()->dispatch('civi.api4.validate', $e);
+    if (!empty($e->errors)) {
+      throw $e->toException();
+    }
+  }
+
+  protected function onValidateValues(ValidateValuesEvent $e) {
+    $errorWeightMap = \CRM_Core_Error_Log::getMap();
+    $errorWeight = $errorWeightMap[$this->getErrorLevel()];
+
+    if (count($e->records) !== 1) {
+      throw new \CRM_Core_Exception("Expected exactly one record to validate");
+    }
+    foreach ($e->records as $recordKey => $record) {
+      /** @var \Civi\WorkflowMessage\WorkflowMessageInterface $w */
+      $w = $this->_model = WorkflowMessage::create($this->getWorkflow(), [
+        'modelProps' => $record,
+      ]);
+      $fields = $w->getFields();
+
+      $unknowns = array_diff(array_keys($record), array_keys($fields));
+      foreach ($unknowns as $fieldName) {
+        $e->addError($recordKey, $fieldName, 'unknown_field', ts('Unknown field (%1). Templates may only be executed with supported fields.', [
+          1 => $fieldName,
+        ]));
+      }
+
+      // Merge intrinsic validations
+      foreach ($w->validate() as $issue) {
+        if ($errorWeightMap[$issue['severity']] < $errorWeight) {
+          $e->addError($recordKey, $issue['fields'], $issue['name'], $issue['message']);
+        }
+      }
+
+      // Add checks which don't fit in WFM::validate
+      foreach ($fields as $fieldName => $fieldSpec) {
+        $fieldValue = $record[$fieldName] ?? NULL;
+        if ($fieldSpec->getFkEntity() && !empty($fieldValue)) {
+          if (!empty($params['check_permissions']) && !\Civi\Api4\Utils\CoreUtil::checkAccessDelegated($fieldSpec->getFkEntity(), 'get', ['id' => $fieldValue], CRM_Core_Session::getLoggedInContactID() ?: 0)) {
+            $e->addError($recordKey, $fieldName, 'nonexistent_id', ts('Referenced record does not exist or is not visible (%1).', [
+              1 => $this->getWorkflow() . '::' . $fieldName,
+            ]));
+          }
+        }
+      }
+    }
+  }
+
+  public function fields() {
+    return [];
+    // We don't currently get the name of the workflow. But if we do...
+    //$item = \Civi\WorkflowMessage\WorkflowMessage::create($this->workflow);
+    ///** @var \Civi\WorkflowMessage\FieldSpec[] $fields */
+    //$fields = $item->getFields();
+    //$array = [];
+    //foreach ($fields as $name => $field) {
+    //  $array[$name] = $field->toArray();
+    //}
+    //return $array;
+  }
+
+}
diff --git a/Civi/Api4/ExampleData.php b/Civi/Api4/ExampleData.php
new file mode 100644
index 000000000000..c53f430b1b9b
--- /dev/null
+++ b/Civi/Api4/ExampleData.php
@@ -0,0 +1,107 @@
+<?php
+/*
+ +--------------------------------------------------------------------+
+ | Copyright CiviCRM LLC. All rights reserved.                        |
+ |                                                                    |
+ | This work is published under the GNU AGPLv3 license with some      |
+ | permitted exceptions and without any warranty. For full license    |
+ | and copyright information, see https://civicrm.org/licensing       |
+ +--------------------------------------------------------------------+
+ */
+
+namespace Civi\Api4;
+
+/**
+ * Search for example data.
+ *
+ * @searchable none
+ * @since 5.43
+ * @package Civi\Api4
+ */
+class ExampleData extends \Civi\Api4\Generic\AbstractEntity {
+
+  /**
+   * @param bool $checkPermissions
+   * @return Generic\AbstractGetAction
+   */
+  public static function get($checkPermissions = TRUE) {
+    return (new Action\ExampleData\Get(__CLASS__, __FILE__))
+      ->setCheckPermissions($checkPermissions);
+  }
+
+  /**
+   * @param bool $checkPermissions
+   * @return Generic\BasicGetFieldsAction
+   */
+  public static function getFields($checkPermissions = TRUE) {
+    return (new Generic\BasicGetFieldsAction(__CLASS__, __FUNCTION__, function () {
+      return [
+        [
+          'name' => 'name',
+          'title' => 'Example Name',
+          'data_type' => 'String',
+        ],
+        [
+          'name' => 'title',
+          'title' => 'Example Title',
+          'data_type' => 'String',
+        ],
+        [
+          'name' => 'workflow',
+          'title' => 'Workflow Name',
+          'data_type' => 'String',
+        ],
+        [
+          'name' => 'file',
+          'title' => 'File Path',
+          'data_type' => 'String',
+          'description' => 'If the example is loaded from a file, this is the location.',
+        ],
+        [
+          'name' => 'tags',
+          'title' => 'Tags',
+          'data_type' => 'Array',
+          'options'  => [
+            'preview' => ts('Preview: Display as an example in the "Preview" dialog'),
+            'phpunit' => ts('PHPUnit: Run basic sniff tests in PHPUnit using this example'),
+          ],
+        ],
+        [
+          'type' => 'Extra',
+          'name' => 'data',
+          'title' => 'Example data',
+          'data_type' => 'String',
+          'serialize' => \CRM_Core_DAO::SERIALIZE_JSON,
+        ],
+        [
+          'type' => 'Extra',
+          'name' => 'asserts',
+          'title' => 'Test assertions',
+          'data_type' => 'String',
+          'serialize' => \CRM_Core_DAO::SERIALIZE_JSON,
+        ],
+      ];
+    }))->setCheckPermissions($checkPermissions);
+  }
+
+  /**
+   * @return array
+   */
+  public static function permissions() {
+    return [
+      // FIXME: Perhaps use 'edit message templates' or similar?
+      "meta" => ["access CiviCRM"],
+      "default" => ["administer CiviCRM"],
+    ];
+  }
+
+  /**
+   * @inheritDoc
+   */
+  public static function getInfo() {
+    $info = parent::getInfo();
+    $info['primary_key'] = ['name'];
+    return $info;
+  }
+
+}
diff --git a/Civi/Api4/WorkflowMessage.php b/Civi/Api4/WorkflowMessage.php
new file mode 100644
index 000000000000..5369e84df1b4
--- /dev/null
+++ b/Civi/Api4/WorkflowMessage.php
@@ -0,0 +1,139 @@
+<?php
+
+/*
+ +--------------------------------------------------------------------+
+ | Copyright CiviCRM LLC. All rights reserved.                        |
+ |                                                                    |
+ | This work is published under the GNU AGPLv3 license with some      |
+ | permitted exceptions and without any warranty. For full license    |
+ | and copyright information, see https://civicrm.org/licensing       |
+ +--------------------------------------------------------------------+
+ */
+
+/**
+ *
+ * @package CRM
+ * @copyright CiviCRM LLC https://civicrm.org/licensing
+ */
+
+namespace Civi\Api4;
+
+/**
+ * A WorkflowMessage describes the inputs to an automated email messages, and it
+ * allows you to render or preview the content fo automated email messages.
+ *
+ * For example, when a constituent donates online, CiviContribute uses the
+ * `contribution_online_receipt` workflow message. This expects certain inputs
+ * (eg `contactId` and `contributionId`) and supports certain tokens
+ * (eg `{contribution.total_amount}`).
+ *
+ * WorkflowMessages are related to MessageTemplates (by way of
+ * `WorkflowMessage.name`<=>`MessageTemplate.workflow_name`).
+ * The WorkflowMessage defines the _contract_ or _processing_ of the
+ * message, and the MessageTemplate defines the _literal prose_.  The prose
+ * would change frequently (eg for different deployments, locales, timeframes,
+ * and other whims), but contract would change conservatively (eg with a
+ * code-update and with some attention to backward-compatibility/change-management).
+ *
+ * @searchable none
+ * @since 5.43
+ * @package Civi\Api4
+ */
+class WorkflowMessage extends Generic\AbstractEntity {
+
+  /**
+   * @param bool $checkPermissions
+   * @return Generic\BasicGetAction
+   */
+  public static function get($checkPermissions = TRUE) {
+    return (new Generic\BasicGetAction(__CLASS__, __FUNCTION__, function ($get) {
+      return \Civi\WorkflowMessage\WorkflowMessage::getWorkflowSpecs();
+    }))->setCheckPermissions($checkPermissions);
+  }
+
+  /**
+   * @param bool $checkPermissions
+   *
+   * @return \Civi\Api4\Action\WorkflowMessage\Render
+   */
+  public static function render($checkPermissions = TRUE) {
+    return (new Action\WorkflowMessage\Render(__CLASS__, __FUNCTION__))
+      ->setCheckPermissions($checkPermissions);
+  }
+
+  /**
+   * @param bool $checkPermissions
+   * @return Generic\BasicGetFieldsAction
+   */
+  public static function getTemplateFields($checkPermissions = TRUE) {
+    return (new Action\WorkflowMessage\GetTemplateFields(__CLASS__, __FUNCTION__))
+      ->setCheckPermissions($checkPermissions);
+  }
+
+  /**
+   * @param bool $checkPermissions
+   * @return Generic\BasicGetFieldsAction
+   */
+  public static function getFields($checkPermissions = TRUE) {
+    return (new Generic\BasicGetFieldsAction(__CLASS__, __FUNCTION__, function() {
+      return [
+        [
+          'name' => 'name',
+          'title' => 'Name',
+          'data_type' => 'String',
+        ],
+        [
+          'name' => 'group',
+          'title' => 'Group',
+          'data_type' => 'String',
+        ],
+        [
+          'name' => 'class',
+          'title' => 'Class',
+          'data_type' => 'String',
+        ],
+        [
+          'name' => 'description',
+          'title' => 'Description',
+          'data_type' => 'String',
+        ],
+        [
+          'name' => 'support',
+          'title' => 'Support Level',
+          'options'  => [
+            'experimental' => ts('Experimental: Message may change substantively with no special communication or facilitation.'),
+            'template-only' => ts('Template Support: Changes affecting the content of the message-template will get active support/facilitation.'),
+            'full' => ts('Full Support: All changes affecting message-templates or message-senders will get active support/facilitation.'),
+          ],
+          'data_type' => 'String',
+        ],
+      ];
+    }))->setCheckPermissions($checkPermissions);
+  }
+
+  public static function permissions() {
+    return [
+      'meta' => ['access CiviCRM'],
+      'default' => ['administer CiviCRM'],
+      'render' => [
+        // nested array = OR
+        [
+          'edit message templates',
+          'edit user-driven message templates',
+          'edit system workflow message templates',
+          'render templates',
+        ],
+      ],
+    ];
+  }
+
+  /**
+   * @inheritDoc
+   */
+  public static function getInfo() {
+    $info = parent::getInfo();
+    $info['primary_key'] = ['name'];
+    return $info;
+  }
+
+}
diff --git a/Civi/Test.php b/Civi/Test.php
index cf9c841ab798..ff498544235d 100644
--- a/Civi/Test.php
+++ b/Civi/Test.php
@@ -182,6 +182,29 @@ public static function data() {
     return self::$singletons['data'];
   }
 
+  /**
+   * @return \Civi\Test\ExampleDataLoader
+   */
+  public static function examples(): \Civi\Test\ExampleDataLoader {
+    if (!isset(self::$singletons['examples'])) {
+      self::$singletons['examples'] = new \Civi\Test\ExampleDataLoader();
+    }
+    return self::$singletons['examples'];
+  }
+
+  /**
+   * @param string $name
+   *   Symbolic name of the data-set.
+   * @return array
+   */
+  public static function example(string $name): array {
+    $result = static::examples()->getFull($name);
+    if ($result === NULL) {
+      throw new \CRM_Core_Exception("Failed to load example data-set: $name");
+    }
+    return $result;
+  }
+
   /**
    * Prepare and execute a batch of SQL statements.
    *
diff --git a/Civi/Test/ExampleDataInterface.php b/Civi/Test/ExampleDataInterface.php
new file mode 100644
index 000000000000..1389b05cdd3d
--- /dev/null
+++ b/Civi/Test/ExampleDataInterface.php
@@ -0,0 +1,32 @@
+<?php
+/*
+ +--------------------------------------------------------------------+
+ | Copyright CiviCRM LLC. All rights reserved.                        |
+ |                                                                    |
+ | This work is published under the GNU AGPLv3 license with some      |
+ | permitted exceptions and without any warranty. For full license    |
+ | and copyright information, see https://civicrm.org/licensing       |
+ +--------------------------------------------------------------------+
+ */
+
+namespace Civi\Test;
+
+interface ExampleDataInterface {
+
+  /**
+   * Get list of examples (summary-info only).
+   *
+   * This data should be static and amenable to caching.
+   */
+  public function getExamples(): iterable;
+
+  /**
+   * Fill-in full details of the example.
+   *
+   * @param array $example
+   *   We start with summary-info for this example (name, title, tags).
+   *   We may expand upon the example record, filling in dynamic(ish) properties like $example['data'].
+   */
+  public function build(array &$example): void;
+
+}
diff --git a/Civi/Test/ExampleDataLoader.php b/Civi/Test/ExampleDataLoader.php
new file mode 100644
index 000000000000..115f0a8de908
--- /dev/null
+++ b/Civi/Test/ExampleDataLoader.php
@@ -0,0 +1,135 @@
+<?php
+/*
+ +--------------------------------------------------------------------+
+ | Copyright CiviCRM LLC. All rights reserved.                        |
+ |                                                                    |
+ | This work is published under the GNU AGPLv3 license with some      |
+ | permitted exceptions and without any warranty. For full license    |
+ | and copyright information, see https://civicrm.org/licensing       |
+ +--------------------------------------------------------------------+
+ */
+
+namespace Civi\Test;
+
+class ExampleDataLoader {
+
+  /**
+   * These are "heavy" properties which are not cached. i.e.
+   *  - They are generated by `$ex->build($example);`
+   *  - They are not generated by '$ex->getExamples();'
+   *  - They are returned by `$this->getFull()`
+   *  - They are not returned by `$this->getMeta()`.
+   */
+  const HEAVY_FIELDS = 'data,asserts';
+
+  /**
+   * @var array|null
+   */
+  private $metas;
+
+  /**
+   * Get a list of all examples, including basic metadata (name, title, workflow).
+   *
+   * @return array
+   *   Ex: ['my_example' => ['title' => ..., 'workflow' => ..., 'tags' => ...]]
+   * @throws \ReflectionException
+   */
+  public function getMetas(): array {
+    if ($this->metas === NULL) {
+      // $cache = new \CRM_Utils_Cache_NoCache([]);
+      $cache = \CRM_Utils_Constant::value('CIVICRM_TEST') ? new \CRM_Utils_Cache_NoCache([]) : \Civi::cache('long');
+      $cacheKey = \CRM_Utils_String::munge(__CLASS__);
+      $this->metas = $cache->get($cacheKey);
+      if ($this->metas === NULL) {
+        $this->metas = $this->findMetas();
+        $cache->set($cacheKey, $this->metas);
+      }
+    }
+    return $this->metas;
+  }
+
+  public function getMeta(string $name): ?array {
+    $all = $this->getMetas();
+    return $all[$name] ?? NULL;
+  }
+
+  /**
+   * @param string $name
+   *
+   * @return array|null
+   */
+  public function getFull(string $name): ?array {
+    $example = $this->getMeta($name);
+    if ($example === NULL) {
+      return NULL;
+    }
+
+    if ($example['file']) {
+      include_once $example['file'];
+    }
+    $obj = new $example['class']();
+    $obj->build($example);
+    return $example;
+  }
+
+  /**
+   * Get a list of all examples, including basic metadata (name, title, workflow).
+   *
+   * @return array
+   *   Ex: ['my_example' => ['title' => ..., 'workflow' => ..., 'tags' => ...]]
+   * @throws \ReflectionException
+   */
+  protected function findMetas(): array {
+    $classes = array_merge(
+      // This scope of search is decidedly narrow - it should probably be expanded.
+      $this->scanExampleClasses(\Civi::paths()->getPath('[civicrm.root]/'), 'CRM/*/WorkflowMessage', '_'),
+      $this->scanExampleClasses(\Civi::paths()->getPath('[civicrm.root]/'), 'Civi/*/WorkflowMessage', '\\'),
+      $this->scanExampleClasses(\Civi::paths()->getPath('[civicrm.root]/'), 'Civi/WorkflowMessage', '\\'),
+      $this->scanExampleClasses(\Civi::paths()->getPath('[civicrm.root]/tests/phpunit/'), 'CRM/*/WorkflowMessage', '_'),
+      $this->scanExampleClasses(\Civi::paths()->getPath('[civicrm.root]/tests/phpunit/'), 'Civi/*/WorkflowMessage', '\\')
+    );
+
+    $all = [];
+    foreach ($classes as $file => $class) {
+      require_once $file;
+      $obj = new $class();
+      $offset = 0;
+      foreach ($obj->getExamples() as $example) {
+        $example['file'] = $file;
+        $example['class'] = $class;
+        if (!isset($example['name'])) {
+          $example['name'] = $example['class'] . '#' . $offset;
+        }
+        $all[$example['name']] = $example;
+        $offset++;
+      }
+    }
+
+    return $all;
+  }
+
+  /**
+   * @param $classRoot
+   *   Ex: Civi root dir.
+   * @param $classDir
+   *   Folder to search (within the parent).
+   * @param $classDelim
+   *   Namespace separator, eg underscore or backslash.
+   * @return array
+   *   Array(string $relativeFileName => string $className).
+   */
+  private function scanExampleClasses($classRoot, $classDir, $classDelim): array {
+    $r = [];
+    $exDirs = (array) glob($classRoot . $classDir);
+    foreach ($exDirs as $exDir) {
+      foreach (\CRM_Utils_File::findFiles($exDir, '*.ex.php') as $file) {
+        $file = str_replace(DIRECTORY_SEPARATOR, '/', $file);
+        $file = \CRM_Utils_File::relativize($file, \CRM_Utils_File::addTrailingSlash($classRoot, '/'));
+        $class = str_replace('/', $classDelim, preg_replace('/\.ex\.php$/', '', $file));
+        $r[$file] = $class;
+      }
+    }
+    return $r;
+  }
+
+}
diff --git a/Civi/Test/WorkflowMessageTestTrait.php b/Civi/Test/WorkflowMessageTestTrait.php
new file mode 100644
index 000000000000..1c4bd7780510
--- /dev/null
+++ b/Civi/Test/WorkflowMessageTestTrait.php
@@ -0,0 +1,82 @@
+<?php
+/*
+ +--------------------------------------------------------------------+
+ | Copyright CiviCRM LLC. All rights reserved.                        |
+ |                                                                    |
+ | This work is published under the GNU AGPLv3 license with some      |
+ | permitted exceptions and without any warranty. For full license    |
+ | and copyright information, see https://civicrm.org/licensing       |
+ +--------------------------------------------------------------------+
+ */
+
+namespace Civi\Test;
+
+use Civi\WorkflowMessage\WorkflowMessage;
+
+trait WorkflowMessageTestTrait {
+
+  abstract public function getWorkflowClass(): string;
+
+  public function getWorkflowName(): string {
+    $class = $this->getWorkflowClass();
+    return $class::WORKFLOW;
+  }
+
+  /**
+   * @return \Civi\Api4\Generic\AbstractGetAction
+   * @throws \API_Exception
+   */
+  protected function findExamples(): \Civi\Api4\Generic\AbstractGetAction {
+    return \Civi\Api4\ExampleData::get(0)
+      ->setSelect(['name', 'title', 'tags', 'data', 'asserts'])
+      ->addWhere('name', 'LIKE', 'workflow/' . $this->getWorkflowName() . '/%')
+      ->addWhere('tags', 'CONTAINS', 'phpunit');
+  }
+
+  /**
+   * @param array $exampleProps
+   * @param string $exampleName
+   * @throws \Civi\WorkflowMessage\Exception\WorkflowMessageException
+   */
+  protected function assertConstructorEquivalence(array $exampleProps, $exampleName = ''): void {
+    $class = $this->getWorkflowClass();
+    $instances = [];
+    $instances["factory_$exampleName"] = WorkflowMessage::create($this->getWorkflowName(), $exampleProps);
+    $instances["class_$exampleName"] = new $class($exampleProps);
+
+    /** @var \Civi\WorkflowMessage\WorkflowMessageInterface $refInstance */
+    /** @var \Civi\WorkflowMessage\WorkflowMessageInterface $cmpInstance */
+
+    $refName = $refInstance = NULL;
+    $comparisons = 0;
+    foreach ($instances as $cmpName => $cmpInstance) {
+      if ($refName === NULL) {
+        $refName = $cmpName;
+        $refInstance = $cmpInstance;
+        continue;
+      }
+
+      $this->assertSameWorkflowMessage($refInstance, $cmpInstance, "Compare $refName vs $cmpName: ");
+      $comparisons++;
+    }
+    $this->assertEquals(1, $comparisons);
+  }
+
+  /**
+   * @param \Civi\WorkflowMessage\WorkflowMessageInterface $refInstance
+   * @param \Civi\WorkflowMessage\WorkflowMessageInterface $cmpInstance
+   * @param string|null $prefix
+   */
+  protected function assertSameWorkflowMessage(\Civi\WorkflowMessage\WorkflowMessageInterface $refInstance, \Civi\WorkflowMessage\WorkflowMessageInterface $cmpInstance, ?string $prefix = NULL): void {
+    if ($prefix === NULL) {
+      $prefix = sprintf('[%s] ', $this->getWorkflowName());
+    }
+    $this->assertEquals($refInstance->export('tplParams'), $cmpInstance->export('tplParams'), "{$prefix}Should have same export(tplParams)");
+    $this->assertEquals($refInstance->export('tokenContext'), $cmpInstance->export('tokenContext'), "{$prefix}should have same export(tokenContext)");
+    $this->assertEquals($refInstance->export('envelope'), $cmpInstance->export('envelope'), "{$prefix}Should have same export(envelope)");
+    $refExportAll = WorkflowMessage::exportAll($refInstance);
+    $cmpExportAll = WorkflowMessage::exportAll($cmpInstance);
+    $this->assertEquals($refExportAll, $cmpExportAll, "{$prefix}Should have same exportAll()");
+  }
+
+}
diff --git a/Civi/Token/TokenCompatSubscriber.php b/Civi/Token/TokenCompatSubscriber.php
index 417450ef93b3..8e9abec17287 100644
--- a/Civi/Token/TokenCompatSubscriber.php
+++ b/Civi/Token/TokenCompatSubscriber.php
@@ -303,7 +303,7 @@ public function onRender(TokenRenderEvent $e) {
     $e->string = \CRM_Utils_Token::replaceDomainTokens($e->string, $domain, $isHtml, $e->message['tokens'], $useSmarty);
 
     if (!empty($e->context['contact'])) {
-      \CRM_Utils_Token::replaceGreetingTokens($e->string, $e->context['contact'], $e->context['contact']['contact_id'], NULL, $useSmarty);
+      \CRM_Utils_Token::replaceGreetingTokens($e->string, $e->context['contact'], $e->context['contact']['contact_id'] ?? $e->context['contactId'], NULL, $useSmarty);
     }
 
     if ($useSmarty) {
diff --git a/Civi/WorkflowMessage/GenericWorkflowMessage.php b/Civi/WorkflowMessage/GenericWorkflowMessage.php
index 862c3a8d42cf..0c072a485e10 100644
--- a/Civi/WorkflowMessage/GenericWorkflowMessage.php
+++ b/Civi/WorkflowMessage/GenericWorkflowMessage.php
@@ -24,6 +24,10 @@
  * @method int|null getContactId()
  * @method $this setContact(array|null $contact)
  * @method array|null getContact()
+ *
+ * @support template-only
+ * GenericWorkflowMessage should aim for "full" support, but it's prudent to keep
+ * it flexible for the first few months. Consider updating to "full" after Dec 2021.
  */
 class GenericWorkflowMessage implements WorkflowMessageInterface {
 
diff --git a/Civi/WorkflowMessage/GenericWorkflowMessage/Alex.ex.php b/Civi/WorkflowMessage/GenericWorkflowMessage/Alex.ex.php
new file mode 100644
index 000000000000..5a7ba7d43762
--- /dev/null
+++ b/Civi/WorkflowMessage/GenericWorkflowMessage/Alex.ex.php
@@ -0,0 +1,96 @@
+<?php
+
+namespace Civi\WorkflowMessage\GenericWorkflowMessage;
+
+class Alex extends \Civi\WorkflowMessage\WorkflowMessageExample {
+
+  /**
+   * @inheritDoc
+   */
+  public function getExamples(): iterable {
+    yield [
+      'name' => "workflow/{$this->wfName}/{$this->exName}",
+      'tags' => [],
+    ];
+  }
+
+  /**
+   * @inheritDoc
+   */
+  public function build(array &$example): void {
+    $example['data'] = [
+      'modelProps' => [
+        'contact' => [
+          'contact_id' => '100',
+          'contact_type' => 'Individual',
+          'contact_sub_type' => NULL,
+          'sort_name' => 'D\u00edaz, Alex',
+          'display_name' => 'Dr. Alex D\u00edaz',
+          'do_not_email' => '1',
+          'do_not_phone' => '1',
+          'do_not_mail' => '0',
+          'do_not_sms' => '0',
+          'do_not_trade' => '0',
+          'is_opt_out' => '0',
+          'legal_identifier' => NULL,
+          'external_identifier' => NULL,
+          'nick_name' => NULL,
+          'legal_name' => NULL,
+          'image_URL' => NULL,
+          'preferred_communication_method' => NULL,
+          'preferred_language' => NULL,
+          'preferred_mail_format' => 'Both',
+          'first_name' => 'Alex',
+          'middle_name' => '',
+          'last_name' => 'D\u00edaz',
+          'prefix_id' => '4',
+          'suffix_id' => NULL,
+          'formal_title' => NULL,
+          'communication_style_id' => NULL,
+          'job_title' => NULL,
+          'gender_id' => '1',
+          'birth_date' => '1994-04-21',
+          'is_deceased' => '0',
+          'deceased_date' => NULL,
+          'household_name' => NULL,
+          'organization_name' => NULL,
+          'sic_code' => NULL,
+          'contact_is_deleted' => '0',
+          'current_employer' => NULL,
+          'address_id' => NULL,
+          'street_address' => NULL,
+          'supplemental_address_1' => NULL,
+          'supplemental_address_2' => NULL,
+          'supplemental_address_3' => NULL,
+          'city' => NULL,
+          'postal_code_suffix' => NULL,
+          'postal_code' => NULL,
+          'geo_code_1' => NULL,
+          'geo_code_2' => NULL,
+          'state_province_id' => NULL,
+          'country_id' => NULL,
+          'phone_id' => '7',
+          'phone_type_id' => '1',
+          'phone' => '293-6934',
+          'email_id' => '7',
+          'email' => 'daz.alex67@testing.net',
+          'on_hold' => '0',
+          'im_id' => NULL,
+          'provider_id' => NULL,
+          'im' => NULL,
+          'worldregion_id' => NULL,
+          'world_region' => NULL,
+          'languages' => NULL,
+          'individual_prefix' => 'Dr.',
+          'individual_suffix' => NULL,
+          'communication_style' => NULL,
+          'gender' => 'Female',
+          'state_province_name' => NULL,
+          'state_province' => NULL,
+          'country' => NULL,
+        ],
+      ],
+    ];
+  }
+
+}
diff --git a/Civi/WorkflowMessage/WorkflowMessage.php b/Civi/WorkflowMessage/WorkflowMessage.php
index 3647286ef558..32593418bbdd 100644
--- a/Civi/WorkflowMessage/WorkflowMessage.php
+++ b/Civi/WorkflowMessage/WorkflowMessage.php
@@ -12,6 +12,7 @@
 
 namespace Civi\WorkflowMessage;
 
+use Civi\Api4\Utils\ReflectionUtils;
 use Civi\WorkflowMessage\Exception\WorkflowMessageException;
 
 /**
@@ -170,4 +171,38 @@ public static function getWorkflowNameClassMap() {
     return $map;
   }
 
+  /**
+   * Get general description of available workflow-messages.
+   *
+   * @return array
+   *   Array(string $workflowName => string $className).
+   *   Ex: ["case_activity" => ["name" => "case_activity", "group" => "msg_workflow_case"]
+   * @internal
+   */
+  public static function getWorkflowSpecs() {
+    $compute = function() {
+      $keys = ['name', 'group', 'class', 'description', 'comment', 'support'];
+      $list = [];
+      foreach (self::getWorkflowNameClassMap() as $name => $class) {
+        $specs = [
+          'name' => $name,
+          'group' => \CRM_Utils_Constant::value($class . '::GROUP'),
+          'class' => $class,
+        ];
+        $list[$name] = \CRM_Utils_Array::subset(
+          array_merge(ReflectionUtils::getCodeDocs(new \ReflectionClass($class)), $specs),
+          $keys);
+      }
+      return $list;
+    };
+
+    $cache = \Civi::cache('long');
+    $cacheKey = 'WorkflowMessage-' . __FUNCTION__;
+    $list = $cache->get($cacheKey);
+    if ($list === NULL) {
+      $cache->set($cacheKey, $list = $compute());
+    }
+    return $list;
+  }
+
 }
diff --git a/Civi/WorkflowMessage/WorkflowMessageExample.php b/Civi/WorkflowMessage/WorkflowMessageExample.php
new file mode 100644
index 000000000000..899c0a91653b
--- /dev/null
+++ b/Civi/WorkflowMessage/WorkflowMessageExample.php
@@ -0,0 +1,79 @@
+<?php
+/*
+ +--------------------------------------------------------------------+
+ | Copyright CiviCRM LLC. All rights reserved.                        |
+ |                                                                    |
+ | This work is published under the GNU AGPLv3 license with some      |
+ | permitted exceptions and without any warranty. For full license    |
+ | and copyright information, see https://civicrm.org/licensing       |
+ +--------------------------------------------------------------------+
+ */
+
+namespace Civi\WorkflowMessage;
+
+use Civi\Test\ExampleDataInterface;
+
+/**
+ * Helper class for defining WorkflowMessage example-data.
+ *
+ * By convention, you should name this class relative to the target workflow, as in:
+ * - Workflow Name: case_activity
+ * - Workflow Class: CRM_Case_WorkflowMessage_CaseActivity
+ * - Example Data: CRM_Case_WorkflowMessage_CaseActivity_Foo
+ * - Example Name: workflow/case_activity/foo
+ */
+abstract class WorkflowMessageExample implements ExampleDataInterface {
+
+  /**
+   * Name of the workflow for which we are providing example data.
+   *
+   * @var string
+   *   Ex: 'CRM_Case_WorkflowMessage_CaseActivity'
+   */
+  protected $wfClass;
+
+  /**
+   * Name of the workflow for which we are providing example data.
+   *
+   * @var string|null
+   *   Ex: 'case_activity'
+   */
+  protected $wfName;
+
+  /**
+   * Name for this example specifically.
+   *
+   * @var string
+   */
+  protected $exName;
+
+  /**
+   * WorkflowMessageExample constructor.
+   */
+  public function __construct() {
+    if (!preg_match(';^(.*)[_\\\]([a-zA-Z0-9]+)$;', static::class, $m)) {
+      throw new \RuntimeException("Failed to parse class: " . static::class);
+    }
+    $this->wfClass = $m[1];
+    $this->wfName = array_search($m[1], \Civi\WorkflowMessage\WorkflowMessage::getWorkflowNameClassMap());
+    $this->exName = $m[2];
+  }
+
+  /**
+   * Get an example, merge/extend it with more data, and return the extended
+   * variant.
+   *
+   * @param array $base
+   *   Baseline data to build upon.
+   * @param array $overrides
+   *   Additional data to recursively add.
+   *
+   * @return array
+   *   The result of merging the original example with the $overrides.
+   */
+  public function extend($base, $overrides = []) {
+    \CRM_Utils_Array::extend($base, $overrides);
+    return $base;
+  }
+
+}
diff --git a/tests/phpunit/CRM/Case/WorkflowMessage/CaseActivity.php b/tests/phpunit/CRM/Case/WorkflowMessage/CaseActivity.php
new file mode 100644
index 000000000000..738f57cd26c0
--- /dev/null
+++ b/tests/phpunit/CRM/Case/WorkflowMessage/CaseActivity.php
@@ -0,0 +1,121 @@
+<?php
+/*
+ +--------------------------------------------------------------------+
+ | Copyright CiviCRM LLC. All rights reserved.                        |
+ |                                                                    |
+ | This work is published under the GNU AGPLv3 license with some      |
+ | permitted exceptions and without any warranty. For full license    |
+ | and copyright information, see https://civicrm.org/licensing       |
+ +--------------------------------------------------------------------+
+ */
+
+/**
+ * When an activity is created in a case, the "case_activity" email is sent.
+ * Generally, the email is sent to the assignee, although (depending on
+ * the configuration/add-ons) additional copies may be sent.
+ *
+ * @see CRM_Case_BAO_Case::sendActivityCopy
+ * @support template-only
+ */
+class CRM_Case_WorkflowMessage_CaseActivity extends Civi\WorkflowMessage\GenericWorkflowMessage {
+
+  const GROUP = 'msg_tpl_workflow_case';
+  const WORKFLOW = 'case_activity';
+
+  /**
+   * The recipient of the notification. The `{contact.*}` tokens will reference this person.
+   *
+   * Example: ['contact_id' => 123, 'display_name' => 'Bob Roberts', role => 'FIXME']
+   *
+   * @var array|null
+   * @scope tokenContext, tplParams
+   * @fkEntity Contact
+   * @required
+   */
+  public $contact;
+
+  /**
+   * The primary contact associated with this case (eg `civicrm_case_contact.contact_id`).
+   *
+   * Existing callers are inconsistent about setting this parameter.
+   *
+   * By default, CiviCRM allows one client on any given case, and this should reflect
+   * that contact. However, some systems may enable multiple clients per case.
+   * This field may not make sense in the long-term.
+   *
+   * @var int
+   * @scope tplParams as client_id
+   * @fkEntity Contact
+   */
+  public $clientId;
+
+  /**
+   * @var string
+   * @scope tplParams
+   * @required
+   */
+  public $activitySubject;
+
+  /**
+   * @var string
+   * @scope tplParams
+   * @required
+   */
+  public $activityTypeName;
+
+  /**
+   * Unique ID for this activity. Unique and difficult to guess.
+   *
+   * @var string
+   * @scope tplParams
+   * @required
+   */
+  public $idHash;
+
+  /**
+   * @var bool
+   * @scope tplParams
+   * @required
+   */
+  public $isCaseActivity;
+
+  /**
+   * @var string
+   * @scope tplParams
+   */
+  public $editActURL;
+
+  /**
+   * @var string
+   * @scope tplParams
+   */
+  public $viewActURL;
+
+  /**
+   * @var string
+   * @scope tplParams
+   */
+  public $manageCaseURL;
+
+  /**
+   * List of conventional activity fields.
+   *
+   * Example: [['label' => ..., 'category' => ..., 'type' => ..., 'value' => ...]]
+   *
+   * @var array
+   * @scope tplParams as activity.fields
+   * @required
+   */
+  public $activityFields;
+
+  /**
+   * List of custom activity fields, grouped by CustomGroup.
+   *
+   * Example: ['My Custom Stuff' => [['label' => ..., 'category' => ..., 'type' => ..., 'value' => ...]]]
+   *
+   * @var array
+   * @scope tplParams as activity.customGroups
+   */
+  public $activityCustomGroups = [];
+
+}
diff --git a/tests/phpunit/CRM/Case/WorkflowMessage/CaseActivity/CaseAdhocExample.ex.php b/tests/phpunit/CRM/Case/WorkflowMessage/CaseActivity/CaseAdhocExample.ex.php
new file mode 100644
index 000000000000..e05b2590ccf6
--- /dev/null
+++ b/tests/phpunit/CRM/Case/WorkflowMessage/CaseActivity/CaseAdhocExample.ex.php
@@ -0,0 +1,49 @@
+<?php
+
+class CRM_Case_WorkflowMessage_CaseActivity_CaseAdhocExample extends \Civi\WorkflowMessage\WorkflowMessageExample {
+
+  /**
+   * @inheritDoc
+   */
+  public function getExamples(): iterable {
+    yield [
+      'name' => "workflow/{$this->wfName}/{$this->exName}",
+      'title' => ts('Case Activity (Adhoc-style example)'),
+      'tags' => [],
+    ];
+  }
+
+  /**
+   * @inheritDoc
+   */
+  public function build(array &$example): void {
+    $alex = \Civi\Test::example('workflow/generic/Alex');
+    $contact = $this->extend($alex['data']['modelProps']['contact'], [
+      'role' => 'myrole',
+    ]);
+    $example['data'] = [
+      'workflow' => $this->wfName,
+      'tokenContext' => [
+        'contact' => $contact,
+      ],
+      'tplParams' => [
+        'contact' => $contact,
+        'isCaseActivity' => 1,
+        'client_id' => 101,
+        'activityTypeName' => 'Follow up',
+        'activitySubject' => 'Test 123',
+        'idHash' => 'abcdefg',
+        'activity' => [
+          'fields' => [
+            [
+              'label' => 'Case ID',
+              'type' => 'String',
+              'value' => '1234',
+            ],
+          ],
+        ],
+      ],
+    ];
+  }
+
+}
diff --git a/tests/phpunit/CRM/Case/WorkflowMessage/CaseActivity/CaseModelExample.ex.php b/tests/phpunit/CRM/Case/WorkflowMessage/CaseActivity/CaseModelExample.ex.php
new file mode 100644
index 000000000000..b661afa0772e
--- /dev/null
+++ b/tests/phpunit/CRM/Case/WorkflowMessage/CaseActivity/CaseModelExample.ex.php
@@ -0,0 +1,49 @@
+<?php
+class CRM_Case_WorkflowMessage_CaseActivity_CaseModelExample extends \Civi\WorkflowMessage\WorkflowMessageExample {
+
+  /**
+   * @inheritDoc
+   */
+  public function getExamples(): iterable {
+    yield [
+      'name' => "workflow/{$this->wfName}/{$this->exName}",
+      'title' => ts('Case Activity (Class-style example)'),
+      'tags' => ['phpunit', 'preview'],
+    ];
+  }
+
+  /**
+   * @inheritDoc
+   */
+  public function build(array &$example): void {
+    $alex = \Civi\Test::example('workflow/generic/Alex');
+    $example['data'] = $this->extend($alex['data'], [
+      'workflow' => $this->wfName,
+      'modelProps' => [
+        'contact' => [
+          'role' => 'myrole',
+        ],
+        'isCaseActivity' => 1,
+        'clientId' => 101,
+        'activityTypeName' => 'Follow up',
+        'activityFields' => [
+          [
+            'label' => 'Case ID',
+            'type' => 'String',
+            'value' => '1234',
+          ],
+        ],
+        'activitySubject' => 'Test 123',
+        'activityCustomGroups' => [],
+        'idHash' => 'abcdefg',
+      ],
+    ]);
+    $example['asserts'] = [
+      'default' => [
+        ['for' => 'subject', 'regex' => '/\[case #abcdefg\] Test 123/'],
+        ['for' => 'text', 'regex' => '/Your Case Role\(s\) : myrole/'],
+      ],
+    ];
+  }
+
+}
diff --git a/tests/phpunit/CRM/Case/WorkflowMessage/CaseActivityTest.php b/tests/phpunit/CRM/Case/WorkflowMessage/CaseActivityTest.php
new file mode 100644
index 000000000000..8d29866cf640
--- /dev/null
+++ b/tests/phpunit/CRM/Case/WorkflowMessage/CaseActivityTest.php
@@ -0,0 +1,78 @@
+<?php
+
+/*
+ +--------------------------------------------------------------------+
+ | Copyright CiviCRM LLC. All rights reserved.                        |
+ |                                                                    |
+ | This work is published under the GNU AGPLv3 license with some      |
+ | permitted exceptions and without any warranty. For full license    |
+ | and copyright information, see https://civicrm.org/licensing       |
+ +--------------------------------------------------------------------+
+ */
+
+/**
+ * Class CRM_Case_WorkflowMessage_CaseActivityTest
+ */
+class CRM_Case_WorkflowMessage_CaseActivityTest extends CiviUnitTestCase {
+  use \Civi\Test\WorkflowMessageTestTrait;
+
+  public function getWorkflowClass(): string {
+    return CRM_Case_WorkflowMessage_CaseActivity::class;
+  }
+
+  public function testAdhocClassEquiv() {
+    $examples = \Civi\Api4\ExampleData::get(0)
+      ->setSelect(['name', 'data'])
+      ->addWhere('name', 'IN', ['workflow/case_activity/CaseAdhocExample', 'workflow/case_activity/CaseModelExample'])
+      ->execute()
+      ->indexBy('name')
+      ->column('data');
+    $byAdhoc = Civi\WorkflowMessage\WorkflowMessage::create('case_activity', $examples['workflow/case_activity/CaseAdhocExample']);
+    $byClass = new CRM_Case_WorkflowMessage_CaseActivity($examples['workflow/case_activity/CaseModelExample']);
+    $this->assertSameWorkflowMessage($byClass, $byAdhoc, 'Compare byClass and byAdhoc: ');
+  }
+
+  /**
+   * Ensure that various methods of constructing a WorkflowMessage all produce similar results.
+   *
+   * To see this, we take all the example data and use it with diff constructors.
+   */
+  public function testConstructorEquivalence() {
+    $examples = $this->findExamples()->execute()->indexBy('name')->column('data');
+    $this->assertTrue(count($examples) >= 1, 'Must have at least one example data-set');
+    foreach ($examples as $example) {
+      $this->assertConstructorEquivalence($example);
+    }
+  }
+
+  /**
+   * Basic canary test fetching a specific example.
+   *
+   * @throws \API_Exception
+   * @throws \Civi\API\Exception\UnauthorizedException
+   */
+  public function testExampleGet() {
+    $file = \Civi::paths()->getPath('[civicrm.root]/tests/phpunit/CRM/Case/WorkflowMessage/CaseActivity/CaseModelExample.ex.php');
+    $name = 'workflow/case_activity/CaseModelExample';
+
+    $this->assertTrue(file_exists($file), "Expect find canary file ($file)");
+
+    $get = \Civi\Api4\ExampleData::get()
+      ->addWhere('name', '=', $name)
+      ->execute()
+      ->single();
+    $this->assertEquals($name, $get['name']);
+    $this->assertTrue(!isset($get['data']));
+    $this->assertTrue(!isset($get['asserts']));
+
+    $get = \Civi\Api4\ExampleData::get()
+      ->addWhere('name', '=', $name)
+      ->addSelect('data')
+      ->execute()
+      ->single();
+    $this->assertEquals($name, $get['name']);
+    $this->assertEquals(100, $get['data']['modelProps']['contact']['contact_id']);
+    $this->assertEquals('myrole', $get['data']['modelProps']['contact']['role']);
+  }
+
+}
diff --git a/tests/phpunit/CRM/Core/BAO/MessageTemplateTest.php b/tests/phpunit/CRM/Core/BAO/MessageTemplateTest.php
index b288a7ca98ec..f3ae76088940 100644
--- a/tests/phpunit/CRM/Core/BAO/MessageTemplateTest.php
+++ b/tests/phpunit/CRM/Core/BAO/MessageTemplateTest.php
@@ -195,38 +195,37 @@ public function testCaseActivityCopyTemplate():void {
     $client_id = $this->individualCreate();
     $contact_id = $this->individualCreate();
 
-    $tplParams = [
-      'isCaseActivity' => 1,
-      'client_id' => $client_id,
-      // activityTypeName means label here not name, but it's ok because label is desired here (dev/core#1116-ok-label)
-      'activityTypeName' => 'Follow up',
-      'activity' => [
-        'fields' => [
+    $msg = \Civi\WorkflowMessage\WorkflowMessage::create('case_activity', [
+      'modelProps' => [
+        'contactId' => $contact_id,
+        'contact' => ['role' => 'Sand grain counter'],
+        'isCaseActivity' => 1,
+        'clientId' => $client_id,
+        // activityTypeName means label here not name, but it's ok because label is desired here (dev/core#1116-ok-label)
+        'activityTypeName' => 'Follow up',
+        'activityFields' => [
           [
             'label' => 'Case ID',
             'type' => 'String',
             'value' => '1234',
           ],
         ],
+        'activitySubject' => 'Test 123',
+        'idHash' => substr(sha1(CIVICRM_SITE_KEY . '1234'), 0, 7),
       ],
-      'activitySubject' => 'Test 123',
-      'idHash' => substr(sha1(CIVICRM_SITE_KEY . '1234'), 0, 7),
-      'contact' => ['role' => 'Sand grain counter'],
-    ];
+    ]);
 
-    [, $subject, $message] = CRM_Core_BAO_MessageTemplate::sendTemplate(
-      [
-        'valueName' => 'case_activity',
-        'contactId' => $contact_id,
-        'tplParams' => $tplParams,
-        'from' => 'admin@example.com',
-        'toName' => 'Demo',
-        'toEmail' => 'admin@example.com',
-        'attachments' => NULL,
-      ]
-    );
+    $this->assertEquals([], \Civi\Test\Invasive::get([$msg, '_extras']));
+
+    [, $subject, $message] = $msg->sendTemplate([
+      'valueName' => 'case_activity',
+      'from' => 'admin@example.com',
+      'toName' => 'Demo',
+      'toEmail' => 'admin@example.com',
+      'attachments' => NULL,
+    ]);
 
-    $this->assertEquals('[case #' . $tplParams['idHash'] . '] Test 123', $subject);
+    $this->assertEquals('[case #' . $msg->getIdHash() . '] Test 123', $subject);
     $this->assertStringContainsString('Your Case Role(s) : Sand grain counter', $message);
     $this->assertStringContainsString('Case ID : 1234', $message);
   }
diff --git a/tests/phpunit/api/v4/Entity/ExampleDataTest.php b/tests/phpunit/api/v4/Entity/ExampleDataTest.php
new file mode 100644
index 000000000000..8f71f57240fe
--- /dev/null
+++ b/tests/phpunit/api/v4/Entity/ExampleDataTest.php
@@ -0,0 +1,66 @@
+<?php
+
+/*
+ +--------------------------------------------------------------------+
+ | Copyright CiviCRM LLC. All rights reserved.                        |
+ |                                                                    |
+ | This work is published under the GNU AGPLv3 license with some      |
+ | permitted exceptions and without any warranty. For full license    |
+ | and copyright information, see https://civicrm.org/licensing       |
+ +--------------------------------------------------------------------+
+ */
+
+/**
+ *
+ * @package CRM
+ * @copyright CiviCRM LLC https://civicrm.org/licensing
+ */
+
+
+namespace api\v4\Entity;
+
+use api\v4\UnitTestCase;
+
+/**
+ * @group headless
+ */
+class ExampleDataTest extends UnitTestCase {
+
+  /**
+   * Basic canary test fetching a specific example.
+   *
+   * @throws \API_Exception
+   * @throws \Civi\API\Exception\UnauthorizedException
+   */
+  public function testGet() {
+    $file = \Civi::paths()->getPath('[civicrm.root]/Civi/WorkflowMessage/GenericWorkflowMessage/Alex.ex.php');
+    $name = 'workflow/generic/Alex';
+
+    $this->assertTrue(file_exists($file), "Expect find canary file ($file)");
+
+    $get = \Civi\Api4\ExampleData::get()
+      ->addWhere('name', '=', $name)
+      ->execute()
+      ->single();
+    $this->assertEquals($name, $get['name']);
+    $this->assertTrue(!isset($get['data']), 'Default "get" should not return "data"');
+    $this->assertTrue(!isset($get['asserts']), 'Default "get" should not return "asserts"');
+
+    $get = \Civi\Api4\ExampleData::get()
+      ->addWhere('name', 'LIKE', 'workflow/generic/%')
+      ->execute();
+    $this->assertTrue($get->count() > 0);
+    foreach ($get as $gotten) {
+      $this->assertStringStartsWith('workflow/generic/', $gotten['name']);
+    }
+
+    $get = \Civi\Api4\ExampleData::get()
+      ->addWhere('name', '=', $name)
+      ->addSelect('workflow', 'data')
+      ->execute()
+      ->single();
+    $this->assertEquals($name, $get['name']);
+    $this->assertEquals(100, $get['data']['modelProps']['contact']['contact_id']);
+  }
+
+}
diff --git a/tests/phpunit/api/v4/Entity/WorkflowMessageTest.php b/tests/phpunit/api/v4/Entity/WorkflowMessageTest.php
new file mode 100644
index 000000000000..43cef7085b02
--- /dev/null
+++ b/tests/phpunit/api/v4/Entity/WorkflowMessageTest.php
@@ -0,0 +1,94 @@
+<?php
+
+/*
+ +--------------------------------------------------------------------+
+ | Copyright CiviCRM LLC. All rights reserved.                        |
+ |                                                                    |
+ | This work is published under the GNU AGPLv3 license with some      |
+ | permitted exceptions and without any warranty. For full license    |
+ | and copyright information, see https://civicrm.org/licensing       |
+ +--------------------------------------------------------------------+
+ */
+
+/**
+ *
+ * @package CRM
+ * @copyright CiviCRM LLC https://civicrm.org/licensing
+ */
+
+
+namespace api\v4\Entity;
+
+use api\v4\UnitTestCase;
+use Civi\Api4\WorkflowMessage;
+
+/**
+ * @group headless
+ */
+class WorkflowMessageTest extends UnitTestCase {
+
+  public function testGet() {
+    $result = \Civi\Api4\WorkflowMessage::get(0)
+      ->addWhere('name', 'LIKE', 'case%')
+      ->execute()
+      ->indexBy('name');
+    $this->assertTrue(isset($result['case_activity']));
+  }
+
+  public function testRenderDefaultTemplate() {
+    $ex = \Civi\Api4\ExampleData::get(0)
+      ->addWhere('name', '=', 'workflow/case_activity/CaseModelExample')
+      ->addSelect('data')
+      ->addChain('render', WorkflowMessage::render()
+        ->setWorkflow('$data.workflow')
+        ->setValues('$data.modelProps'))
+      ->execute()
+      ->single();
+    $result = $ex['render'][0];
+    $this->assertRegExp('/Case ID : 1234/', $result['text']);
+  }
+
+  public function testRenderCustomTemplate() {
+    $ex = \Civi\Api4\ExampleData::get(0)
+      ->addWhere('name', '=', 'workflow/case_activity/CaseModelExample')
+      ->addSelect('data')
+      ->execute()
+      ->single();
+    $result = \Civi\Api4\WorkflowMessage::render(0)
+      ->setWorkflow('case_activity')
+      ->setValues($ex['data']['modelProps'])
+      ->setMessageTemplate([
+        'msg_text' => 'The role is {$contact.role}.',
+      ])
+      ->execute()
+      ->single();
+    $this->assertRegExp('/The role is myrole./', $result['text']);
+  }
+
+  public function testRenderExamples() {
+    $examples = \Civi\Api4\ExampleData::get(0)
+      ->addWhere('tags', 'CONTAINS', 'phpunit')
+      ->addSelect('name', 'data', 'asserts')
+      ->execute();
+    $this->assertTrue($examples->rowCount >= 1);
+    foreach ($examples as $example) {
+      $this->assertTrue(!empty($example['data']['modelProps']), sprintf("Example (%s) is tagged phpunit. It should have modelProps.", $example['name']));
+      $this->assertTrue(!empty($example['asserts']['default']), sprintf("Example (%s) is tagged phpunit. It should have assertions.", $example['name']));
+      $result = \Civi\Api4\WorkflowMessage::render(0)
+        ->setWorkflow($example['data']['workflow'])
+        ->setValues($example['data']['modelProps'])
+        ->execute()
+        ->single();
+      foreach ($example['asserts']['default'] as $num => $assert) {
+        $msg = sprintf('Check assertion(%s) on example (%s)', $num, $example['name']);
+        if (isset($assert['regex'])) {
+          $this->assertRegExp($assert['regex'], $result[$assert['for']], $msg);
+        }
+        else {
+          $this->fail('Unrecognized assertion: ' . json_encode($assert));
+        }
+      }
+    }
+  }
+
+}