track modal model updates

assets/javascripts/discourse/components/modal/assign-user.hbs

@@ -1,7 +1,7 @@
 <DModal class="assign" @title={{this.title}} @closeModal={{@closeModal}}>
   <:body>
     <AssignUserForm
-      @model={{@model}}
+      @model={{this.model}}
       @onSubmit={{this.onSubmit}}
       @formApi={{this.formApi}}
     />
@@ -12,7 +12,7 @@
       class="btn-primary"
       @action={{this.formApi.submit}}
       @label={{if
-        @model.reassign
+        this.model.reassign
         "discourse_assign.reassign.title"
         "discourse_assign.assign_modal.assign"
       }}

assets/javascripts/discourse/components/modal/assign-user.js

@@ -1,11 +1,14 @@
 import Component from "@glimmer/component";
 import { action } from "@ember/object";
 import { inject as service } from "@ember/service";
+import { TrackedObject } from "@ember-compat/tracked-built-ins";
 import I18n from "I18n";
 
 export default class AssignUser extends Component {
   @service taskActions;
 
+  model = new TrackedObject(this.args.model);
+
   // `submit` property will be mutated by the `AssignUserForm` component
   formApi = {
     submit() {},
@@ -14,7 +17,7 @@ export default class AssignUser extends Component {
   get title() {
     let i18nSuffix;
 
-    switch (this.args.model.targetType) {
+    switch (this.model.targetType) {
       case "Post":
         i18nSuffix = "_post_modal";
         break;
@@ -25,7 +28,7 @@ export default class AssignUser extends Component {
 
     return I18n.t(
       `discourse_assign.assign${i18nSuffix}.${
-        this.args.model.reassign ? "reassign_title" : "title"
+        this.model.reassign ? "reassign_title" : "title"
       }`
     );
   }
@@ -33,6 +36,6 @@ export default class AssignUser extends Component {
   @action
   async onSubmit() {
     this.args.closeModal();
-    await this.taskActions.assign(this.args.model);
+    await this.taskActions.assign(this.model);
   }
 }