diff --git a/core/client/app/adapters/base.js b/core/client/app/adapters/base.js
index 427459f05e..d1de3edea5 100644
--- a/core/client/app/adapters/base.js
+++ b/core/client/app/adapters/base.js
@@ -1,10 +1,15 @@
 import DS from 'ember-data';
 import ghostPaths from 'ghost/utils/ghost-paths';
+import Ember from 'ember';
+
+const {inject} = Ember;
 
 export default DS.RESTAdapter.extend({
     host: window.location.origin,
     namespace: ghostPaths().apiRoot.slice(1),
 
+    session: inject.service('session'),
+
     shouldBackgroundReloadRecord: function () {
         return false;
     },
@@ -43,5 +48,15 @@ export default DS.RESTAdapter.extend({
         return response.then(function () {
             return null;
         });
+    },
+
+    handleResponse: function (status) {
+        if (status === 401) {
+            if (this.get('session.isAuthenticated')) {
+                this.get('session').invalidate();
+            }
+        }
+
+        return this._super(...arguments);
     }
 });
diff --git a/core/client/app/components/gh-selectize.js b/core/client/app/components/gh-selectize.js
index fedda43960..c377797e05 100644
--- a/core/client/app/components/gh-selectize.js
+++ b/core/client/app/components/gh-selectize.js
@@ -17,16 +17,18 @@ export default EmberSelectizeComponent.extend({
         if (!openOnFocus) {
             Ember.run.next(this, function () {
                 var selectize = this._selectize;
-                selectize.on('dropdown_open', function () {
-                    if (Ember.isBlank(selectize.$control_input.val())) {
-                        selectize.close();
-                    }
-                });
-                selectize.on('type', function (filter) {
-                    if (Ember.isBlank(filter)) {
-                        selectize.close();
-                    }
-                });
+                if (selectize) {
+                    selectize.on('dropdown_open', function () {
+                        if (Ember.isBlank(selectize.$control_input.val())) {
+                            selectize.close();
+                        }
+                    });
+                    selectize.on('type', function (filter) {
+                        if (Ember.isBlank(filter)) {
+                            selectize.close();
+                        }
+                    });
+                }
             });
         }
     }),
diff --git a/core/client/app/controllers/modals/signin.js b/core/client/app/controllers/modals/signin.js
index cc24022464..c3b2c627c3 100644
--- a/core/client/app/controllers/modals/signin.js
+++ b/core/client/app/controllers/modals/signin.js
@@ -24,6 +24,7 @@ export default Ember.Controller.extend(ValidationEngine, {
             this.get('session').authenticate(authStrategy, this.get('identification'), this.get('password')).then(function () {
                 self.send('closeModal');
                 self.set('password', '');
+                self.get('notifications').closeAlerts('post.save');
             }).catch(function () {
                 // if authentication fails a rejected promise will be returned.
                 // it needs to be caught so it doesn't generate an exception in the console,
diff --git a/core/client/app/controllers/settings/tags/tag.js b/core/client/app/controllers/settings/tags/tag.js
index e6d29e6636..c5678ffee7 100644
--- a/core/client/app/controllers/settings/tags/tag.js
+++ b/core/client/app/controllers/settings/tags/tag.js
@@ -9,6 +9,7 @@ export default Ember.Controller.extend({
     isMobile: alias('tagsController.isMobile'),
 
     tagsController: inject.controller('settings.tags'),
+    notifications: inject.service(),
 
     saveTagProperty: function (propKey, newValue) {
         const tag = this.get('tag'),
@@ -27,10 +28,10 @@ export default Ember.Controller.extend({
 
         tag.save().then((savedTag) => {
             // replace 'new' route with 'tag' route
-            this.replaceWith('settings.tags.tag', savedTag);
+            this.replaceRoute('settings.tags.tag', savedTag);
         }).catch((error) => {
             if (error) {
-                this.notifications.showAPIError(error, {key: 'tag.save'});
+                this.get('notifications').showAPIError(error, {key: 'tag.save'});
             }
         });
     },
diff --git a/core/client/app/mirage/config.js b/core/client/app/mirage/config.js
index ee31e80716..8b3b89b4cb 100644
--- a/core/client/app/mirage/config.js
+++ b/core/client/app/mirage/config.js
@@ -52,6 +52,23 @@ export default function () {
 
     this.get('/notifications/', 'notifications');
 
+    /* Posts ---------------------------------------------------------------- */
+
+    this.post('/posts/', function (db, request) {
+        const [attrs] = JSON.parse(request.requestBody).posts;
+        let post;
+
+        if (isBlank(attrs.slug) && !isBlank(attrs.title)) {
+            attrs.slug = attrs.title.dasherize();
+        }
+
+        post = db.posts.insert(attrs);
+
+        return {
+            posts: [post]
+        };
+    });
+
     /* Settings ------------------------------------------------------------- */
 
     this.get('/settings/', function (db, request) {
@@ -84,6 +101,16 @@ export default function () {
         };
     });
 
+    /* Slugs ---------------------------------------------------------------- */
+
+    this.get('/slugs/post/:slug/', function (db, request) {
+        return {
+            slugs: [
+                {slug: request.params.slug.dasherize}
+            ]
+        };
+    });
+
     /* Tags ----------------------------------------------------------------- */
 
     this.post('/tags/', function (db, request) {
@@ -119,7 +146,7 @@ export default function () {
 
     this.put('/tags/:id/', function (db, request) {
         const id = request.params.id,
-              [attrs] = JSON.parse(request.requestBody).contacts,
+              [attrs] = JSON.parse(request.requestBody).tags,
               record = db.tags.update(id, attrs);
 
         return {
@@ -137,6 +164,8 @@ export default function () {
             users: [db.users.find(1)]
         };
     });
+
+    this.get('/users/', 'users');
 }
 
 /*
diff --git a/core/client/app/mirage/factories/post.js b/core/client/app/mirage/factories/post.js
new file mode 100644
index 0000000000..ef92f336ea
--- /dev/null
+++ b/core/client/app/mirage/factories/post.js
@@ -0,0 +1,6 @@
+/* jscs:disable */
+import Mirage from 'ember-cli-mirage';
+
+export default Mirage.Factory.extend({
+    // TODO: fill in with actual factory data
+});
diff --git a/core/client/app/routes/application.js b/core/client/app/routes/application.js
index 0610cf10d2..1522f6d70e 100644
--- a/core/client/app/routes/application.js
+++ b/core/client/app/routes/application.js
@@ -1,9 +1,11 @@
 /* global key */
 
 import Ember from 'ember';
+import AuthConfiguration from 'ember-simple-auth/configuration';
 import ApplicationRouteMixin from 'ember-simple-auth/mixins/application-route-mixin';
 import ShortcutsRoute from 'ghost/mixins/shortcuts-route';
 import ctrlOrCmd from 'ghost/utils/ctrl-or-cmd';
+import windowProxy from 'ghost/utils/window-proxy';
 
 const shortcuts = {};
 
@@ -42,6 +44,10 @@ export default Ember.Route.extend(ApplicationRouteMixin, ShortcutsRoute, {
         });
     },
 
+    sessionInvalidated: function () {
+        this.send('authorizationFailed');
+    },
+
     actions: {
         openMobileMenu: function () {
             this.controller.set('showMobileMenu', true);
@@ -75,6 +81,10 @@ export default Ember.Route.extend(ApplicationRouteMixin, ShortcutsRoute, {
             });
         },
 
+        authorizationFailed: function () {
+            windowProxy.replaceLocation(AuthConfiguration.baseURL);
+        },
+
         openModal: function (modalName, model, type) {
             this.get('dropdown').closeDropdowns();
             key.setScope('modal');
diff --git a/core/client/app/routes/editor/edit.js b/core/client/app/routes/editor/edit.js
index bd29f217bb..0918538f00 100644
--- a/core/client/app/routes/editor/edit.js
+++ b/core/client/app/routes/editor/edit.js
@@ -36,7 +36,7 @@ export default AuthenticatedRoute.extend(base, {
                 return post;
             }
 
-            return self.replaceWith('posts.index');
+            return self.replaceRoute('posts.index');
         });
     },
 
@@ -45,7 +45,7 @@ export default AuthenticatedRoute.extend(base, {
 
         return self.get('session.user').then(function (user) {
             if (user.get('isAuthor') && !post.isAuthoredByUser(user)) {
-                return self.replaceWith('posts.index');
+                return self.replaceRoute('posts.index');
             }
         });
     },
diff --git a/core/client/app/routes/posts/post.js b/core/client/app/routes/posts/post.js
index 6b4f79d9dd..35e05a880f 100644
--- a/core/client/app/routes/posts/post.js
+++ b/core/client/app/routes/posts/post.js
@@ -32,7 +32,7 @@ export default AuthenticatedRoute.extend(ShortcutsRoute, {
                 return post;
             }
 
-            return self.replaceWith('posts.index');
+            return self.replaceRoute('posts.index');
         });
     },
 
@@ -41,7 +41,7 @@ export default AuthenticatedRoute.extend(ShortcutsRoute, {
 
         return self.get('session.user').then(function (user) {
             if (user.get('isAuthor') && !post.isAuthoredByUser(user)) {
-                return self.replaceWith('posts.index');
+                return self.replaceRoute('posts.index');
             }
         });
     },
diff --git a/core/client/app/templates/editor/edit.hbs b/core/client/app/templates/editor/edit.hbs
index 1baf984241..db5aa1a795 100644
--- a/core/client/app/templates/editor/edit.hbs
+++ b/core/client/app/templates/editor/edit.hbs
@@ -1,8 +1,7 @@
 {{#gh-editor editorScrollInfo=editorScrollInfo as |ghEditor|}}
     <header class="view-header">
         {{#gh-view-title classNames="gh-editor-title" openMobileMenu="openMobileMenu"}}
-            {{gh-trim-focus-input type="text" id="entry-title"placeholder="Your Post Title" value=model.titleScratch
-        tabindex="1" focus=shouldFocusTitle}}
+            {{gh-trim-focus-input type="text" id="entry-title" placeholder="Your Post Title" value=model.titleScratch tabindex="1" focus=shouldFocusTitle}}
         {{/gh-view-title}}
         <section class="view-actions">
             <button type="button" class="post-settings" title="Post Settings" {{action "openSettingsMenu"}}>
diff --git a/core/client/app/utils/window-proxy.js b/core/client/app/utils/window-proxy.js
new file mode 100644
index 0000000000..6ea9012527
--- /dev/null
+++ b/core/client/app/utils/window-proxy.js
@@ -0,0 +1,9 @@
+export default {
+    changeLocation: function (url) {
+        window.location = url;
+    },
+
+    replaceLocation: function (url) {
+        window.location.replace(url);
+    }
+};
diff --git a/core/client/tests/acceptance/authentication-test.js b/core/client/tests/acceptance/authentication-test.js
new file mode 100644
index 0000000000..6c1ca6b00b
--- /dev/null
+++ b/core/client/tests/acceptance/authentication-test.js
@@ -0,0 +1,132 @@
+/* jshint expr:true */
+import {
+    describe,
+    it,
+    beforeEach,
+    afterEach
+} from 'mocha';
+import { expect } from 'chai';
+import Ember from 'ember';
+import startApp from '../helpers/start-app';
+import { authenticateSession, currentSession, invalidateSession } from 'ghost/tests/helpers/ember-simple-auth';
+import Mirage from 'ember-cli-mirage';
+import windowProxy from 'ghost/utils/window-proxy';
+
+const {run} = Ember;
+
+describe('Acceptance: Authentication', function () {
+    let application,
+        originalReplaceLocation;
+
+    beforeEach(function () {
+        application = startApp();
+    });
+
+    afterEach(function () {
+        run(application, 'destroy');
+    });
+
+    describe('general page', function () {
+        beforeEach(function () {
+            originalReplaceLocation = windowProxy.replaceLocation;
+            windowProxy.replaceLocation = function (url) {
+                visit(url);
+            };
+
+            server.loadFixtures();
+            const role = server.create('role', {name: 'Administrator'}),
+                  user = server.create('user', {roles: [role], slug: 'test-user'});
+        });
+
+        afterEach(function () {
+            windowProxy.replaceLocation = originalReplaceLocation;
+        });
+
+        it('invalidates session on 401 API response', function () {
+            const role = server.create('role', {name: 'Administrator'}),
+                  user = server.create('user', {roles: [role]});
+
+            // return a 401 when attempting to retrieve tags
+            server.get('/users/', (db, request) => {
+                return new Mirage.Response(401, {}, {
+                    errors: [
+                        {message: 'Access denied.', errorType: 'UnauthorizedError'}
+                    ]
+                });
+            });
+
+            authenticateSession(application);
+            visit('/team');
+
+            andThen(() => {
+                expect(currentURL(), 'url after 401').to.equal('/signin');
+            });
+        });
+    });
+
+    describe('editor', function () {
+        let origDebounce = Ember.run.debounce;
+        let origThrottle = Ember.run.throttle;
+
+        // we don't want the autosave interfering in this test
+        beforeEach(function () {
+            Ember.run.debounce = function () { };
+            Ember.run.throttle = function () { };
+        });
+
+        it('displays re-auth modal attempting to save with invalid session', function () {
+            const role = server.create('role', {name: 'Administrator'}),
+                  user = server.create('user', {roles: [role]});
+
+            // simulate an invalid session when saving the edited post
+            server.put('/posts/:id/', (db, request) => {
+                let post = db.posts.find(request.params.id),
+                    [attrs] = JSON.parse(request.requestBody).posts;
+
+                if (attrs.markdown === 'Edited post body') {
+                    return new Mirage.Response(401, {}, {
+                        errors: [
+                            {message: 'Access denied.', errorType: 'UnauthorizedError'}
+                        ]
+                    });
+                } else {
+                    return {
+                        posts: [post]
+                    };
+                }
+            });
+
+            server.loadFixtures();
+            authenticateSession(application);
+
+            visit('/editor');
+
+            // create the post
+            fillIn('#entry-title', 'Test Post');
+            fillIn('textarea.markdown-editor', 'Test post body');
+            click('.js-publish-button');
+
+            andThen(() => {
+                // we shouldn't have a modal at this point
+                expect(find('.modal-container #login').length, 'modal exists').to.equal(0);
+                // we also shouldn't have any alerts
+                expect(find('.gh-alert').length, 'no of alerts').to.equal(0);
+            });
+
+            // update the post
+            fillIn('textarea.markdown-editor', 'Edited post body');
+            click('.js-publish-button');
+
+            andThen(() => {
+                // we should see a re-auth modal
+                expect(find('.modal-container #login').length, 'modal exists').to.equal(1);
+            });
+        });
+
+        // don't clobber debounce/throttle for future tests
+        afterEach(function () {
+            Ember.run.debounce = origDebounce;
+            Ember.run.throttle = origThrottle;
+        });
+    });
+});
diff --git a/core/client/tests/acceptance/settings/tags-test.js b/core/client/tests/acceptance/settings/tags-test.js
index c33ee5161c..a5afe6eb03 100644
--- a/core/client/tests/acceptance/settings/tags-test.js
+++ b/core/client/tests/acceptance/settings/tags-test.js
@@ -79,7 +79,7 @@ describe('Acceptance: Settings - Tags', function () {
             // TODO: this should always be run for acceptance tests
             server.loadFixtures();
 
-            authenticateSession(application);
+            return authenticateSession(application);
         });
 
         it('it renders, can be navigated, can edit, create & delete tags', function () {
@@ -138,7 +138,9 @@ describe('Acceptance: Settings - Tags', function () {
                     keydown(38);
                     keyup(38);
                 });
+            });
 
+            andThen(() => {
                 // it navigates to previous tag
                 expect(currentURL(), 'url after keyboard up arrow').to.equal(`/settings/tags/${tag1.slug}`);
 
@@ -153,7 +155,9 @@ describe('Acceptance: Settings - Tags', function () {
                     keydown(40);
                     keyup(40);
                 });
+            });
 
+            andThen(() => {
                 // it navigates to previous tag
                 expect(currentURL(), 'url after keyboard down arrow').to.equal(`/settings/tags/${tag2.slug}`);
 
diff --git a/core/client/tests/fixtures/settings.js b/core/client/tests/fixtures/settings.js
deleted file mode 100644
index 380ea124a0..0000000000
--- a/core/client/tests/fixtures/settings.js
+++ /dev/null
@@ -1,51 +0,0 @@
-export default [{
-    created_at: '2015-09-11T09:44:30.805Z',
-    created_by: 1,
-    id: 5,
-    key: 'title',
-    type: 'blog',
-    updated_at: '2015-10-04T16:26:05.195Z',
-    updated_by: 1,
-    uuid: '39e16daf-43fa-4bf0-87d4-44948ba8bf4c',
-    value: 'Test Blog'
-}, {
-    created_at: '2015-09-11T09:44:30.806Z',
-    created_by: 1,
-    id: 6,
-    key: 'description',
-    type: 'blog',
-    updated_at: '2015-10-04T16:26:05.198Z',
-    updated_by: 1,
-    uuid: 'e6c8b636-6925-4c4a-a5d9-1dc0870fb8ea',
-    value: 'Thoughts, stories and ideas.'
-}, {
-    created_at: '2015-09-11T09:44:30.809Z',
-    created_by: 1,
-    id: 10,
-    key: 'postsPerPage',
-    type: 'blog',
-    updated_at: '2015-10-04T16:26:05.211Z',
-    updated_by: 1,
-    uuid: '775e6ca1-bcc3-4347-a53d-15d5d76c04a4',
-    value: '5'
-}, {
-    created_at: '2015-09-11T09:44:30.809Z',
-    created_by: 1,
-    id: 13,
-    key: 'ghost_head',
-    type: 'blog',
-    updated_at: '2015-09-23T13:32:49.858Z',
-    updated_by: 1,
-    uuid: 'df7f3151-bc08-4a77-be9d-dd315b630d51',
-    value: ''
-}, {
-    created_at: '2015-09-11T09:44:30.809Z',
-    created_by: 1,
-    id: 14,
-    key: 'ghost_foot',
-    type: 'blog',
-    updated_at: '2015-09-23T13:32:49.858Z',
-    updated_by: 1,
-    uuid: '0649d45e-828b-4dd0-8381-3dff6d1d5ddb',
-    value: ''
-}];
diff --git a/core/client/tests/unit/mixins/validation-engine-test.js b/core/client/tests/unit/mixins/validation-engine-test.js
new file mode 100644
index 0000000000..63e6f5a685
--- /dev/null
+++ b/core/client/tests/unit/mixins/validation-engine-test.js
@@ -0,0 +1,42 @@
+/* jshint expr:true */
+import { expect } from 'chai';
+import {
+    describe,
+    it
+} from 'mocha';
+import Ember from 'ember';
+import ValidationEngineMixin from 'ghost/mixins/validation-engine';
+
+describe('ValidationEngineMixin', function () {
+    // Replace this with your real tests.
+    // it('works', function () {
+    //     var ValidationEngineObject = Ember.Object.extend(ValidationEngineMixin);
+    //     var subject = ValidationEngineObject.create();
+    //     expect(subject).to.be.ok;
+    // });
+
+    describe('#validate', function () {
+        it('loads the correct validator');
+        it('rejects if the validator doesn\'t exist');
+        it('resolves with valid object');
+        it('rejects with invalid object');
+        it('clears all existing errors');
+
+        describe('with a specified property', function () {
+            it('resolves with valid property');
+            it('rejects with invalid property');
+            it('adds property to hasValidated array');
+            it('clears existing error on specified property');
+        });
+
+        it('handles a passed in model');
+        it('uses this.model if available');
+    });
+
+    describe('#save', function () {
+        it('calls validate');
+        it('rejects with validation errors');
+        it('calls object\'s #save if validation passes');
+        it('skips validation if it\'s a deletion');
+    });
+});
diff --git a/core/client/tests/unit/validators/tag-settings-test.js b/core/client/tests/unit/validators/tag-settings-test.js
index fabe97ed12..a0a106df68 100644
--- a/core/client/tests/unit/validators/tag-settings-test.js
+++ b/core/client/tests/unit/validators/tag-settings-test.js
@@ -22,6 +22,9 @@ const {run} = Ember,
 // TODO: These tests have way too much duplication, consider creating test
 // helpers for validations
 
+// TODO: Move testing of validation-engine behaviour into validation-engine-test
+// and replace these tests with specific validator tests
+
 describe('Unit: Validator: tag-settings', function () {
     it('validates all fields by default', function () {
         let tag = Tag.create({}),