diff --git a/src/__phutil_library_map__.php b/src/__phutil_library_map__.php
index 6f4c7254d0..d5c4451720 100644
--- a/src/__phutil_library_map__.php
+++ b/src/__phutil_library_map__.php
@@ -1530,6 +1530,7 @@ phutil_register_library_map(array(
     'PasteCreateMailReceiver' => 'applications/paste/mail/PasteCreateMailReceiver.php',
     'PasteDefaultEditCapability' => 'applications/paste/capability/PasteDefaultEditCapability.php',
     'PasteDefaultViewCapability' => 'applications/paste/capability/PasteDefaultViewCapability.php',
+    'PasteEditConduitAPIMethod' => 'applications/paste/conduit/PasteEditConduitAPIMethod.php',
     'PasteEmbedView' => 'applications/paste/view/PasteEmbedView.php',
     'PasteInfoConduitAPIMethod' => 'applications/paste/conduit/PasteInfoConduitAPIMethod.php',
     'PasteMailReceiver' => 'applications/paste/mail/PasteMailReceiver.php',
@@ -1571,6 +1572,7 @@ phutil_register_library_map(array(
     'PhabricatorApplicationDetailViewController' => 'applications/meta/controller/PhabricatorApplicationDetailViewController.php',
     'PhabricatorApplicationEditController' => 'applications/meta/controller/PhabricatorApplicationEditController.php',
     'PhabricatorApplicationEditEngine' => 'applications/transactions/editengine/PhabricatorApplicationEditEngine.php',
+    'PhabricatorApplicationEditEngineAPIMethod' => 'applications/transactions/editengine/PhabricatorApplicationEditEngineAPIMethod.php',
     'PhabricatorApplicationEditHTTPParameterHelpView' => 'applications/transactions/view/PhabricatorApplicationEditHTTPParameterHelpView.php',
     'PhabricatorApplicationEmailCommandsController' => 'applications/meta/controller/PhabricatorApplicationEmailCommandsController.php',
     'PhabricatorApplicationLaunchView' => 'applications/meta/view/PhabricatorApplicationLaunchView.php',
@@ -2094,6 +2096,7 @@ phutil_register_library_map(array(
     'PhabricatorEdgeConfig' => 'infrastructure/edges/constants/PhabricatorEdgeConfig.php',
     'PhabricatorEdgeConstants' => 'infrastructure/edges/constants/PhabricatorEdgeConstants.php',
     'PhabricatorEdgeCycleException' => 'infrastructure/edges/exception/PhabricatorEdgeCycleException.php',
+    'PhabricatorEdgeEditType' => 'applications/transactions/edittype/PhabricatorEdgeEditType.php',
     'PhabricatorEdgeEditor' => 'infrastructure/edges/editor/PhabricatorEdgeEditor.php',
     'PhabricatorEdgeGraph' => 'infrastructure/edges/util/PhabricatorEdgeGraph.php',
     'PhabricatorEdgeQuery' => 'infrastructure/edges/query/PhabricatorEdgeQuery.php',
@@ -2101,6 +2104,7 @@ phutil_register_library_map(array(
     'PhabricatorEdgeType' => 'infrastructure/edges/type/PhabricatorEdgeType.php',
     'PhabricatorEdgeTypeTestCase' => 'infrastructure/edges/type/__tests__/PhabricatorEdgeTypeTestCase.php',
     'PhabricatorEditField' => 'applications/transactions/editfield/PhabricatorEditField.php',
+    'PhabricatorEditType' => 'applications/transactions/edittype/PhabricatorEditType.php',
     'PhabricatorEditor' => 'infrastructure/PhabricatorEditor.php',
     'PhabricatorElasticSearchEngine' => 'applications/search/engine/PhabricatorElasticSearchEngine.php',
     'PhabricatorElasticSearchSetupCheck' => 'applications/config/check/PhabricatorElasticSearchSetupCheck.php',
@@ -2936,6 +2940,7 @@ phutil_register_library_map(array(
     'PhabricatorSetupIssue' => 'applications/config/issue/PhabricatorSetupIssue.php',
     'PhabricatorSetupIssueUIExample' => 'applications/uiexample/examples/PhabricatorSetupIssueUIExample.php',
     'PhabricatorSetupIssueView' => 'applications/config/view/PhabricatorSetupIssueView.php',
+    'PhabricatorSimpleEditType' => 'applications/transactions/edittype/PhabricatorSimpleEditType.php',
     'PhabricatorSite' => 'aphront/site/PhabricatorSite.php',
     'PhabricatorSlowvoteApplication' => 'applications/slowvote/application/PhabricatorSlowvoteApplication.php',
     'PhabricatorSlowvoteChoice' => 'applications/slowvote/storage/PhabricatorSlowvoteChoice.php',
@@ -5457,6 +5462,7 @@ phutil_register_library_map(array(
     'PasteCreateMailReceiver' => 'PhabricatorMailReceiver',
     'PasteDefaultEditCapability' => 'PhabricatorPolicyCapability',
     'PasteDefaultViewCapability' => 'PhabricatorPolicyCapability',
+    'PasteEditConduitAPIMethod' => 'PhabricatorApplicationEditEngineAPIMethod',
     'PasteEmbedView' => 'AphrontView',
     'PasteInfoConduitAPIMethod' => 'PasteConduitAPIMethod',
     'PasteMailReceiver' => 'PhabricatorObjectMailReceiver',
@@ -5501,6 +5507,7 @@ phutil_register_library_map(array(
     'PhabricatorApplicationDetailViewController' => 'PhabricatorApplicationsController',
     'PhabricatorApplicationEditController' => 'PhabricatorApplicationsController',
     'PhabricatorApplicationEditEngine' => 'Phobject',
+    'PhabricatorApplicationEditEngineAPIMethod' => 'ConduitAPIMethod',
     'PhabricatorApplicationEditHTTPParameterHelpView' => 'AphrontView',
     'PhabricatorApplicationEmailCommandsController' => 'PhabricatorApplicationsController',
     'PhabricatorApplicationLaunchView' => 'AphrontTagView',
@@ -6121,6 +6128,7 @@ phutil_register_library_map(array(
     'PhabricatorEdgeConfig' => 'PhabricatorEdgeConstants',
     'PhabricatorEdgeConstants' => 'Phobject',
     'PhabricatorEdgeCycleException' => 'Exception',
+    'PhabricatorEdgeEditType' => 'PhabricatorEditType',
     'PhabricatorEdgeEditor' => 'Phobject',
     'PhabricatorEdgeGraph' => 'AbstractDirectedGraph',
     'PhabricatorEdgeQuery' => 'PhabricatorQuery',
@@ -6128,6 +6136,7 @@ phutil_register_library_map(array(
     'PhabricatorEdgeType' => 'Phobject',
     'PhabricatorEdgeTypeTestCase' => 'PhabricatorTestCase',
     'PhabricatorEditField' => 'Phobject',
+    'PhabricatorEditType' => 'Phobject',
     'PhabricatorEditor' => 'Phobject',
     'PhabricatorElasticSearchEngine' => 'PhabricatorSearchEngine',
     'PhabricatorElasticSearchSetupCheck' => 'PhabricatorSetupCheck',
@@ -7120,6 +7129,7 @@ phutil_register_library_map(array(
     'PhabricatorSetupIssue' => 'Phobject',
     'PhabricatorSetupIssueUIExample' => 'PhabricatorUIExample',
     'PhabricatorSetupIssueView' => 'AphrontView',
+    'PhabricatorSimpleEditType' => 'PhabricatorEditType',
     'PhabricatorSite' => 'AphrontSite',
     'PhabricatorSlowvoteApplication' => 'PhabricatorApplication',
     'PhabricatorSlowvoteChoice' => 'PhabricatorSlowvoteDAO',
diff --git a/src/applications/paste/conduit/PasteEditConduitAPIMethod.php b/src/applications/paste/conduit/PasteEditConduitAPIMethod.php
new file mode 100644
index 0000000000..c02fb940e8
--- /dev/null
+++ b/src/applications/paste/conduit/PasteEditConduitAPIMethod.php
@@ -0,0 +1,19 @@
+<?php
+
+final class PasteEditConduitAPIMethod
+  extends PhabricatorApplicationEditEngineAPIMethod {
+
+  public function getAPIMethodName() {
+    return 'paste.edit';
+  }
+
+  public function newEditEngine() {
+    return new PhabricatorPasteEditEngine();
+  }
+
+  public function getMethodSummary() {
+    return pht(
+      'Apply transactions to create a new paste or edit an existing one.');
+  }
+
+}
diff --git a/src/applications/paste/editor/PhabricatorPasteEditor.php b/src/applications/paste/editor/PhabricatorPasteEditor.php
index da39b8beeb..cd7a0f271a 100644
--- a/src/applications/paste/editor/PhabricatorPasteEditor.php
+++ b/src/applications/paste/editor/PhabricatorPasteEditor.php
@@ -72,6 +72,30 @@ final class PhabricatorPasteEditor
     $this->fileName = $name;
   }
 
+  protected function validateTransaction(
+    PhabricatorLiskDAO $object,
+    $type,
+    array $xactions) {
+
+    $errors = parent::validateTransaction($object, $type, $xactions);
+    switch ($type) {
+      case PhabricatorPasteTransaction::TYPE_CONTENT:
+        if (!$object->getFilePHID() && !$xactions) {
+          $error = new PhabricatorApplicationTransactionValidationError(
+            $type,
+            pht('Required'),
+            pht('You must provide content to create a paste.'),
+            null);
+
+          $error->setIsMissingFieldError(true);
+          $errors[] = $error;
+        }
+        break;
+    }
+
+    return $errors;
+  }
+
   protected function getCustomTransactionOldValue(
     PhabricatorLiskDAO $object,
     PhabricatorApplicationTransaction $xaction) {
diff --git a/src/applications/paste/storage/PhabricatorPaste.php b/src/applications/paste/storage/PhabricatorPaste.php
index e156a87ea0..ee381e9493 100644
--- a/src/applications/paste/storage/PhabricatorPaste.php
+++ b/src/applications/paste/storage/PhabricatorPaste.php
@@ -41,6 +41,7 @@ final class PhabricatorPaste extends PhabricatorPasteDAO
 
     return id(new PhabricatorPaste())
       ->setTitle('')
+      ->setLanguage('')
       ->setStatus(self::STATUS_ACTIVE)
       ->setAuthorPHID($actor->getPHID())
       ->setViewPolicy($view_policy)
diff --git a/src/applications/transactions/editengine/PhabricatorApplicationEditEngine.php b/src/applications/transactions/editengine/PhabricatorApplicationEditEngine.php
index c5547a01e8..0205cd5c9c 100644
--- a/src/applications/transactions/editengine/PhabricatorApplicationEditEngine.php
+++ b/src/applications/transactions/editengine/PhabricatorApplicationEditEngine.php
@@ -1,5 +1,10 @@
 <?php
 
+
+/**
+ * @task web Responding to Web Requests
+ * @task conduit Responding to Conduit Requests
+ */
 abstract class PhabricatorApplicationEditEngine extends Phobject {
 
   private $viewer;
@@ -47,6 +52,7 @@ abstract class PhabricatorApplicationEditEngine extends Phobject {
           'capability' => PhabricatorPolicyCapability::CAN_VIEW,
           'label' => pht('View Policy'),
           'description' => pht('Controls who can view the object.'),
+          'edit' => 'view',
         ),
         PhabricatorTransactions::TYPE_EDIT_POLICY => array(
           'key' => 'policy.edit',
@@ -54,6 +60,7 @@ abstract class PhabricatorApplicationEditEngine extends Phobject {
           'capability' => PhabricatorPolicyCapability::CAN_EDIT,
           'label' => pht('Edit Policy'),
           'description' => pht('Controls who can edit the object.'),
+          'edit' => 'edit',
         ),
         PhabricatorTransactions::TYPE_JOIN_POLICY => array(
           'key' => 'policy.join',
@@ -61,6 +68,7 @@ abstract class PhabricatorApplicationEditEngine extends Phobject {
           'capability' => PhabricatorPolicyCapability::CAN_JOIN,
           'label' => pht('Join Policy'),
           'description' => pht('Controls who can join the object.'),
+          'edit' => 'join',
         ),
       );
 
@@ -74,6 +82,7 @@ abstract class PhabricatorApplicationEditEngine extends Phobject {
         $aliases = $spec['aliases'];
         $label = $spec['label'];
         $description = $spec['description'];
+        $edit = $spec['edit'];
 
         $policy_field = id(new PhabricatorPolicyEditField())
           ->setKey($key)
@@ -83,6 +92,7 @@ abstract class PhabricatorApplicationEditEngine extends Phobject {
           ->setCapability($capability)
           ->setPolicies($policies)
           ->setTransactionType($type)
+          ->setEditTypeKey($edit)
           ->setValue($object->getPolicy($capability));
         $fields[] = $policy_field;
 
@@ -93,6 +103,7 @@ abstract class PhabricatorApplicationEditEngine extends Phobject {
               $space_field = id(new PhabricatorSpaceEditField())
                 ->setKey('spacePHID')
                 ->setLabel(pht('Space'))
+                ->setEditTypeKey('space')
                 ->setDescription(
                   pht('Shifts the object in the Spaces application.'))
                 ->setAliases(array('space', 'policy.space'))
@@ -126,6 +137,7 @@ abstract class PhabricatorApplicationEditEngine extends Phobject {
         $edge_field = id(new PhabricatorDatasourceEditField())
           ->setKey('projectPHIDs')
           ->setLabel(pht('Projects'))
+          ->setEditTypeKey('projects')
           ->setDescription(
             pht(
               'Add or remove associated projects.'))
@@ -154,6 +166,7 @@ abstract class PhabricatorApplicationEditEngine extends Phobject {
         $subscribers_field = id(new PhabricatorDatasourceEditField())
           ->setKey('subscriberPHIDs')
           ->setLabel(pht('Subscribers'))
+          ->setEditTypeKey('subscribers')
           ->setDescription(pht('Manage subscribers.'))
           ->setDatasource(new PhabricatorMetaMTAMailableDatasource())
           ->setAliases(array('subscriber', 'subscribers'))
@@ -240,11 +253,9 @@ abstract class PhabricatorApplicationEditEngine extends Phobject {
       if (!$object) {
         return new Aphront404Response();
       }
-
       $this->setIsCreate(false);
     } else {
       $object = $this->newEditableObject();
-
       $this->setIsCreate(true);
     }
 
@@ -443,4 +454,171 @@ abstract class PhabricatorApplicationEditEngine extends Phobject {
     return $actions;
   }
 
+
+/* -(  Conduit  )------------------------------------------------------------ */
+
+
+  /**
+   * Respond to a Conduit edit request.
+   *
+   * This method accepts a list of transactions to apply to an object, and
+   * either edits an existing object or creates a new one.
+   *
+   * @task conduit
+   */
+  final public function buildConduitResponse(ConduitAPIRequest $request) {
+    $viewer = $this->getViewer();
+
+    $phid = $request->getValue('objectPHID');
+    if ($phid) {
+      $object = $this->newObjectQuery()
+        ->setViewer($viewer)
+        ->withPHIDs(array($phid))
+        ->requireCapabilities(
+          array(
+            PhabricatorPolicyCapability::CAN_VIEW,
+            PhabricatorPolicyCapability::CAN_EDIT,
+          ))
+        ->executeOne();
+      if (!$object) {
+        throw new Exception(pht('No such object with PHID "%s".', $phid));
+      }
+      $this->setIsCreate(false);
+    } else {
+      $object = $this->newEditableObject();
+      $this->setIsCreate(true);
+    }
+
+    $fields = $this->buildEditFields($object);
+
+    foreach ($fields as $field) {
+      $field
+        ->setViewer($viewer)
+        ->setObject($object);
+    }
+
+    $types = $this->getAllEditTypesFromFields($fields);
+    $template = $object->getApplicationTransactionTemplate();
+
+    $xactions = $this->getConduitTransactions($request, $types, $template);
+
+    $editor = $object->getApplicationTransactionEditor()
+      ->setActor($viewer)
+      ->setContentSourceFromConduitRequest($request)
+      ->setContinueOnNoEffect(true);
+
+    $xactions = $editor->applyTransactions($object, $xactions);
+
+    $xactions_struct = array();
+    foreach ($xactions as $xaction) {
+      $xactions_struct[] = array(
+        'phid' => $xaction->getPHID(),
+      );
+    }
+
+    return array(
+      'object' => array(
+        'id' => $object->getID(),
+        'phid' => $object->getPHID(),
+      ),
+      'transactions' => $xactions_struct,
+    );
+  }
+
+
+  /**
+   * Generate transactions which can be applied from edit actions in a Conduit
+   * request.
+   *
+   * @param ConduitAPIRequest The request.
+   * @param list<PhabricatorEditType> Supported edit types.
+   * @param PhabricatorApplicationTransaction Template transaction.
+   * @return list<PhabricatorApplicationTransaction> Generated transactions.
+   * @task conduit
+   */
+  private function getConduitTransactions(
+    ConduitAPIRequest $request,
+    array $types,
+    PhabricatorApplicationTransaction $template) {
+
+    $transactions_key = 'transactions';
+
+    $xactions = $request->getValue($transactions_key);
+    if (!is_array($xactions)) {
+      throw new Exception(
+        pht(
+          'Parameter "%s" is not a list of transactions.',
+          $transactions_key));
+    }
+
+    foreach ($xactions as $key => $xaction) {
+      if (!is_array($xaction)) {
+        throw new Exception(
+          pht(
+            'Parameter "%s" must contain a list of transaction descriptions, '.
+            'but item with key "%s" is not a dictionary.',
+            $transactions_key,
+            $key));
+      }
+
+      if (!array_key_exists('type', $xaction)) {
+        throw new Exception(
+          pht(
+            'Parameter "%s" must contain a list of transaction descriptions, '.
+            'but item with key "%s" is missing a "type" field. Each '.
+            'transaction must have a type field.',
+            $transactions_key,
+            $key));
+      }
+
+      $type = $xaction['type'];
+      if (empty($types[$type])) {
+        throw new Exception(
+          pht(
+            'Transaction with key "%s" has invalid type "%s". This type is '.
+            'not recognized. Valid types are: %s.',
+            $key,
+            $type,
+            implode(', ', array_keys($types))));
+      }
+    }
+
+    $results = array();
+    foreach ($xactions as $xaction) {
+      $type = $types[$xaction['type']];
+
+      $results[] = $type->generateTransaction(
+        clone $template,
+        $xaction);
+    }
+
+    return $results;
+  }
+
+
+  /**
+   * @return map<string, PhabricatorEditType>
+   * @task conduit
+   */
+  private function getAllEditTypesFromFields(array $fields) {
+    $types = array();
+    foreach ($fields as $field) {
+      $field_types = $field->getEditTransactionTypes();
+      foreach ($field_types as $field_type) {
+        $field_type->setField($field);
+        $types[$field_type->getEditType()] = $field_type;
+      }
+    }
+    return $types;
+  }
+
+  public function getAllEditTypes() {
+    $object = $this->newEditableObject();
+    $fields = $this->buildEditFields($object);
+    return $this->getAllEditTypesFromFields($fields);
+  }
+
+
+
+
 }
diff --git a/src/applications/transactions/editengine/PhabricatorApplicationEditEngineAPIMethod.php b/src/applications/transactions/editengine/PhabricatorApplicationEditEngineAPIMethod.php
new file mode 100644
index 0000000000..9fc6495455
--- /dev/null
+++ b/src/applications/transactions/editengine/PhabricatorApplicationEditEngineAPIMethod.php
@@ -0,0 +1,188 @@
+<?php
+
+abstract class PhabricatorApplicationEditEngineAPIMethod
+  extends ConduitAPIMethod {
+
+  abstract public function newEditEngine();
+
+  public function getMethodStatus() {
+    return self::METHOD_STATUS_UNSTABLE;
+  }
+
+  public function getMethodStatusDescription() {
+    return pht('ApplicationEditor methods are highly unstable.');
+  }
+
+  final protected function defineParamTypes() {
+    return array(
+      'transactions' => 'list<map<string, wild>>',
+      'objectPHID' => 'optional phid',
+    );
+  }
+
+  final protected function defineReturnType() {
+    return 'map<string, wild>';
+  }
+
+  final protected function execute(ConduitAPIRequest $request) {
+    $engine = $this->newEditEngine()
+      ->setViewer($request->getUser());
+
+    return $engine->buildConduitResponse($request);
+  }
+
+  final public function getMethodDescription() {
+    // TODO: We don't currently have a real viewer in this method.
+    $viewer = new PhabricatorUser();
+
+    $engine = $this->newEditEngine()
+      ->setViewer($viewer);
+
+    $types = $engine->getAllEditTypes();
+
+    $out = array();
+
+    $out[] = pht(<<<EOTEXT
+This is a standard **ApplicationEditor** method which allows you to create and
+modify objects by applying transactions.
+
+Each transaction applies one change to the object. For example, to create an
+object with a specific title or change the title of an existing object you might
+start by building a transaction like this:
+
+```lang=json, name=Example Single Transaction
+{
+  "type": "title",
+  "value": "New Object Title"
+}
+```
+
+By passing a list of transactions in the `transactions` parameter, you can
+apply a sequence of edits. For example, you'll often pass a value like this to
+create an object with several field values or apply changes to multiple fields:
+
+```lang=json, name=Example Transaction List
+[
+  {
+    "type": "title",
+    "value": "New Object Title"
+  },
+  {
+    "type": "body",
+    "value": "New body text for the object."
+  },
+  {
+    "type": "projects.add",
+    "value": ["PHID-PROJ-1111", "PHID-PROJ-2222"]
+  }
+]
+```
+
+Exactly which types of edits are available depends on the object you're editing.
+
+
+Creating Objects
+----------------
+
+To create an object, pass a list of `transactions` but leave `objectPHID`
+empty. This will create a new object with the initial field values you
+specify.
+
+
+Editing Objects
+---------------
+
+To edit an object, pass a list of `transactions` and specify an object to
+apply them to with `objectPHID`. This will apply the changes to the object.
+
+
+Return Type
+-----------
+
+WARNING: The structure of the return value from these methods is likely to
+change as ApplicationEditor evolves.
+
+Return values look something like this for now:
+
+```lang=json, name=Example Return Value
+{
+  "object": {
+    "phid": "PHID-XXXX-1111"
+  },
+  "transactions": [
+    {
+      "phid": "PHID-YYYY-1111",
+    },
+    {
+      "phid": "PHID-YYYY-2222",
+    }
+  ]
+}
+```
+
+The `object` key contains information about the object which was created or
+edited.
+
+The `transactions` key contains information about the transactions which were
+actually applied. For many reasons, the transactions which actually apply may
+be greater or fewer in number than the transactions you provided, or may differ
+in their nature in other ways.
+
+
+Edit Types
+==========
+
+This API method supports these edit types:
+EOTEXT
+      );
+
+    $key = pht('Key');
+    $summary = pht('Summary');
+    $description = pht('Description');
+    $head_type = pht('Type');
+
+    $table = array();
+    $table[] = "| {$key} | {$summary} |";
+    $table[] = '|--------|----------------|';
+    foreach ($types as $type) {
+      $edit_type = $type->getEditType();
+      $edit_summary = $type->getSummary();
+      $table[] = "| `{$edit_type}` | {$edit_summary} |";
+    }
+
+    $out[] = implode("\n", $table);
+
+    foreach ($types as $type) {
+      $section = array();
+      $section[] = pht('Edit Type: %s', $type->getEditType());
+      $section[] = '---------';
+      $section[] = null;
+      $section[] = $type->getDescription();
+      $section[] = null;
+      $section[] = pht(
+        'This edit generates transactions of type `%s` internally.',
+        $type->getTransactionType());
+      $section[] = null;
+
+      $type_description = pht(
+        'Use `%s` to select this edit type.',
+        $type->getEditType());
+
+      $value_type = $type->getValueType();
+      $value_description = $type->getValueDescription();
+
+      $table = array();
+      $table[] = "| {$key} | {$head_type} | {$description} |";
+      $table[] = '|--------|--------------|----------------|';
+      $table[] = "| `type` | `const` | {$type_description} |";
+      $table[] = "| `value` | `{$value_type}` | {$value_description} |";
+      $section[] = implode("\n", $table);
+
+      $out[] = implode("\n", $section);
+    }
+
+    $out = implode("\n\n", $out);
+    return $out;
+  }
+
+}
diff --git a/src/applications/transactions/editfield/PhabricatorEditField.php b/src/applications/transactions/editfield/PhabricatorEditField.php
index fcbd496390..ded3c2acf3 100644
--- a/src/applications/transactions/editfield/PhabricatorEditField.php
+++ b/src/applications/transactions/editfield/PhabricatorEditField.php
@@ -12,6 +12,8 @@ abstract class PhabricatorEditField extends Phobject {
   private $transactionType;
   private $metadata = array();
   private $description;
+  private $editTypeKey;
+
 
   public function setKey($key) {
     $this->key = $key;
@@ -223,4 +225,75 @@ abstract class PhabricatorEditField extends Phobject {
     return 'string';
   }
 
+  public function setEditTypeKey($edit_type_key) {
+    $this->editTypeKey = $edit_type_key;
+    return $this;
+  }
+
+  public function getEditTypeKey() {
+    if ($this->editTypeKey === null) {
+      return $this->getKey();
+    }
+    return $this->editTypeKey;
+  }
+
+  public function getEditTransactionTypes() {
+    $transaction_type = $this->getTransactionType();
+    $type_key = $this->getEditTypeKey();
+
+    // TODO: This is a pretty big pile of hard-coded hacks for now.
+
+    $edge_types = array(
+      PhabricatorTransactions::TYPE_EDGE => array(
+        '+' => pht('Add projects.'),
+        '-' => pht('Remove projects.'),
+        '=' => pht('Set associated projects, overwriting current value.'),
+      ),
+      PhabricatorTransactions::TYPE_SUBSCRIBERS => array(
+        '+' => pht('Add subscribers.'),
+        '-' => pht('Remove subscribers.'),
+        '=' => pht('Set subscribers, overwriting current value.'),
+      ),
+    );
+
+    if (isset($edge_types[$transaction_type])) {
+      $base = id(new PhabricatorEdgeEditType())
+        ->setTransactionType($transaction_type)
+        ->setMetadata($this->metadata);
+
+      $strings = $edge_types[$transaction_type];
+
+      $add = id(clone $base)
+        ->setEditType($type_key.'.add')
+        ->setEdgeOperation('+')
+        ->setDescription($strings['+'])
+        ->setValueDescription(pht('List of PHIDs to add.'));
+      $rem = id(clone $base)
+        ->setEditType($type_key.'.remove')
+        ->setEdgeOperation('-')
+        ->setDescription($strings['-'])
+        ->setValueDescription(pht('List of PHIDs to remove.'));
+      $set = id(clone $base)
+        ->setEditType($type_key.'.set')
+        ->setEdgeOperation('=')
+        ->setDescription($strings['='])
+        ->setValueDescription(pht('List of PHIDs to set.'));
+
+      return array(
+        $add,
+        $rem,
+        $set,
+      );
+    }
+
+    return array(
+      id(new PhabricatorSimpleEditType())
+        ->setEditType($type_key)
+        ->setTransactionType($transaction_type)
+        ->setValueType($this->getHTTPParameterType())
+        ->setDescription($this->getDescription())
+        ->setMetadata($this->metadata),
+    );
+  }
+
 }
diff --git a/src/applications/transactions/edittype/PhabricatorEdgeEditType.php b/src/applications/transactions/edittype/PhabricatorEdgeEditType.php
new file mode 100644
index 0000000000..17d1441a80
--- /dev/null
+++ b/src/applications/transactions/edittype/PhabricatorEdgeEditType.php
@@ -0,0 +1,51 @@
+<?php
+
+final class PhabricatorEdgeEditType extends PhabricatorEditType {
+
+  private $edgeOperation;
+  private $valueDescription;
+
+  public function setEdgeOperation($edge_operation) {
+    $this->edgeOperation = $edge_operation;
+    return $this;
+  }
+
+  public function getEdgeOperation() {
+    return $this->edgeOperation;
+  }
+
+  public function getValueType() {
+    return 'list<phid>';
+  }
+
+  public function generateTransaction(
+    PhabricatorApplicationTransaction $template,
+    array $spec) {
+
+    $value = idx($spec, 'value');
+    $value = array_fuse($value);
+    $value = array(
+      $this->getEdgeOperation() => $value,
+    );
+
+    $template
+      ->setTransactionType($this->getTransactionType())
+      ->setNewValue($value);
+
+    foreach ($this->getMetadata() as $key => $value) {
+      $template->setMetadataValue($key, $value);
+    }
+
+    return $template;
+  }
+
+  public function setValueDescription($value_description) {
+    $this->valueDescription = $value_description;
+    return $this;
+  }
+
+  public function getValueDescription() {
+    return $this->valueDescription;
+  }
+
+}
diff --git a/src/applications/transactions/edittype/PhabricatorEditType.php b/src/applications/transactions/edittype/PhabricatorEditType.php
new file mode 100644
index 0000000000..a1e580f6fd
--- /dev/null
+++ b/src/applications/transactions/edittype/PhabricatorEditType.php
@@ -0,0 +1,76 @@
+<?php
+
+abstract class PhabricatorEditType extends Phobject {
+
+  private $editType;
+  private $transactionType;
+  private $field;
+  private $description;
+  private $summary;
+  private $metadata = array();
+
+  public function setDescription($description) {
+    $this->description = $description;
+    return $this;
+  }
+
+  public function getDescription() {
+    return $this->description;
+  }
+
+  public function setSummary($summary) {
+    $this->summary = $summary;
+    return $this;
+  }
+
+  public function getSummary() {
+    if ($this->summary === null) {
+      return $this->getDescription();
+    }
+    return $this->summary;
+  }
+
+  public function setField(PhabricatorEditField $field) {
+    $this->field = $field;
+    return $this;
+  }
+
+  public function getField() {
+    return $this->field;
+  }
+
+  public function setEditType($edit_type) {
+    $this->editType = $edit_type;
+    return $this;
+  }
+
+  public function getEditType() {
+    return $this->editType;
+  }
+
+  public function setMetadata($metadata) {
+    $this->metadata = $metadata;
+    return $this;
+  }
+
+  public function getMetadata() {
+    return $this->metadata;
+  }
+
+  public function setTransactionType($transaction_type) {
+    $this->transactionType = $transaction_type;
+    return $this;
+  }
+
+  public function getTransactionType() {
+    return $this->transactionType;
+  }
+
+  abstract public function generateTransaction(
+    PhabricatorApplicationTransaction $template,
+    array $spec);
+
+  abstract public function getValueType();
+  abstract public function getValueDescription();
+
+}
diff --git a/src/applications/transactions/edittype/PhabricatorSimpleEditType.php b/src/applications/transactions/edittype/PhabricatorSimpleEditType.php
new file mode 100644
index 0000000000..3aa0575579
--- /dev/null
+++ b/src/applications/transactions/edittype/PhabricatorSimpleEditType.php
@@ -0,0 +1,41 @@
+<?php
+
+final class PhabricatorSimpleEditType extends PhabricatorEditType {
+
+  private $valueType;
+  private $valueDescription;
+
+  public function setValueType($value_type) {
+    $this->valueType = $value_type;
+    return $this;
+  }
+
+  public function getValueType() {
+    return $this->valueType;
+  }
+
+  public function generateTransaction(
+    PhabricatorApplicationTransaction $template,
+    array $spec) {
+
+    $template
+      ->setTransactionType($this->getTransactionType())
+      ->setNewValue(idx($spec, 'value'));
+
+    foreach ($this->getMetadata() as $key => $value) {
+      $template->setMetadataValue($key, $value);
+    }
+
+    return $template;
+  }
+
+  public function setValueDescription($value_description) {
+    $this->valueDescription = $value_description;
+    return $this;
+  }
+
+  public function getValueDescription() {
+    return $this->valueDescription;
+  }
+
+}