[MM-69646] Disallow MoveThreadsEnabled feature flag (fail server startup) (#37966)

* [MM-69646] Disallow MoveThreadsEnabled feature flag

Reject the MoveThreadsEnabled feature flag during config validation so the
server fails to start while it is enabled. The feature is being retired in
favor of Wrangler and will be removed later.

Co-authored-by: mattermost-code <matty-code@mattermost.com>

* [MM-69646] Cover nil FeatureFlags guard in config validation test

Co-authored-by: mattermost-code <matty-code@mattermost.com>

* Move MoveThreadsEnabled comment into isValid method body

Keep isValid's doc comment generic since it will validate more flag
combinations in the future, and place the MoveThreadsEnabled-specific
rationale next to the actual flag check.

* [MM-69646] Update TestMoveThread for retired MoveThreadsEnabled flag

Config.IsValid now rejects enabling MoveThreadsEnabled, so the
move-thread API stays disabled. Replace the enabled-path suite with
assertions that the flag cannot be turned on and MoveThread returns 501.

Co-authored-by: mattermost-code <matty-code@mattermost.com>

* [MM-69646] Stop forcing MoveThreadsEnabled in e2e environments

E2E was setting MM_FEATUREFLAGS_MOVETHREADSENABLED=true, which now fails
Config.IsValid and prevents the test server from starting. Remove the
override and skip Cypress move-thread specs that require the retired flag.

Co-authored-by: mattermost-code <matty-code@mattermost.com>

* [MM-69646] Skip TestMoveThread instead of asserting disabled flag

Mirror the E2E describe.skip approach: retain the original TestMoveThread
body and skip it at the top, since MoveThreadsEnabled is retired and
rejected by Config.IsValid.

* [MM-69646] Park cursor away from post dot menu in edit_file_attachment specs

---------

Co-authored-by: Cursor Agent <cursoragent@cursor.com>
Co-authored-by: mattermost-code <matty-code@mattermost.com>
Co-authored-by: Mattermost Build <build@mattermost.com>
Co-authored-by: Jesse Hallam <jesse@mattermost.com>

e2e-tests/.ci/server.generate.sh

@@ -64,7 +64,6 @@ services:
       MM_EMAILSETTINGS_SMTPSERVER: "localhost"
       MM_CLUSTERSETTINGS_READONLYCONFIG: "false"
       MM_SERVICEENVIRONMENT: "test"
-      MM_FEATUREFLAGS_MOVETHREADSENABLED: "true"
       MM_FEATUREFLAGS_CUSTOMPROFILEATTRIBUTES: "true"
       MM_FEATUREFLAGS_PERMISSIONPOLICIES: "true"
       MM_FEATUREFLAGS_TEAMMEMBERSHIPACCESSCONTROL: "true"

e2e-tests/cypress/tests/integration/channels/move_thread/move_thread_from_dm_spec.js

@@ -12,7 +12,9 @@
 
 import * as TIMEOUTS from '@/fixtures/timeouts';
 
-describe('Move Thread', () => {
+// Skipped: MoveThreadsEnabled is retired and rejected by Config.IsValid (MM-69646).
+// These specs require the flag and cannot run while the server refuses to enable it.
+describe.skip('Move Thread', () => {
     let user1;
     let user2;
     let testTeam;

e2e-tests/cypress/tests/integration/channels/move_thread/move_thread_from_gm_spec.js

@@ -12,7 +12,9 @@
 
 import * as TIMEOUTS from '@/fixtures/timeouts';
 
-describe('Move thread', () => {
+// Skipped: MoveThreadsEnabled is retired and rejected by Config.IsValid (MM-69646).
+// These specs require the flag and cannot run while the server refuses to enable it.
+describe.skip('Move thread', () => {
     let user1;
     let user2;
     let user3;

e2e-tests/cypress/tests/integration/channels/move_thread/move_thread_from_private_channel_spec.js

@@ -12,7 +12,9 @@
 
 import * as TIMEOUTS from '@/fixtures/timeouts';
 
-describe('Move thread', () => {
+// Skipped: MoveThreadsEnabled is retired and rejected by Config.IsValid (MM-69646).
+// These specs require the flag and cannot run while the server refuses to enable it.
+describe.skip('Move thread', () => {
     let user1;
     let testTeam;
     let privateChannel;

e2e-tests/cypress/tests/integration/channels/move_thread/move_thread_from_public_channel_spec.js

@@ -10,7 +10,9 @@
 // Stage: @prod
 // Group: @channels @enterprise @messaging
 
-describe('Move Thread', () => {
+// Skipped: MoveThreadsEnabled is retired and rejected by Config.IsValid (MM-69646).
+// These specs require the flag and cannot run while the server refuses to enable it.
+describe.skip('Move Thread', () => {
     let user1;
     let user2;
     let user3;

e2e-tests/playwright/lib/src/containers/env_baseline.ts

@@ -19,7 +19,6 @@ export const SERVER_ENV_BASELINE: Record<string, string> = {
     // Feature flags this test suite needs on, off by default in the server
     MM_FEATUREFLAGS_ATTRIBUTEVALUEMASKING: 'true',
     MM_FEATUREFLAGS_ENABLEREMOTECLUSTERSERVICE: 'true',
-    MM_FEATUREFLAGS_MOVETHREADSENABLED: 'true',
     MM_FEATUREFLAGS_PERMISSIONPOLICIES: 'true',
     MM_FEATUREFLAGS_PROPERTYFIELDRANK: 'true',
     MM_FEATUREFLAGS_RECURRINGSCHEDULEDPOSTS: 'true',

e2e-tests/playwright/specs/functional/channels/file_attachments/edit_file_attachment.spec.ts

@@ -13,7 +13,7 @@ test('MM-T5654_1 should be able to add attachments while editing a post', {tag:
 
     // # Initialize user and login
     const {user} = await pw.initSetup();
-    const {channelsPage} = await pw.testBrowser.login(user);
+    const {channelsPage, page} = await pw.testBrowser.login(user);
 
     // # Navigate to channels page and post a message
     await channelsPage.goto();
@@ -28,6 +28,7 @@ test('MM-T5654_1 should be able to add attachments while editing a post', {tag:
 
     // # Open the dot menu and click edit
     await post.postMenu.dotMenuButton.click();
+    await moveMouseAway(page);
     await channelsPage.postDotMenu.toBeVisible();
     await channelsPage.postDotMenu.editMenuItem.click();
 
@@ -59,6 +60,7 @@ test('MM-T5654_2 should be able to add attachments while editing a threaded post
 
     // open the dot menu
     await post.postMenu.dotMenuButton.click();
+    await moveMouseAway(page);
     await channelsPage.postDotMenu.toBeVisible();
     await channelsPage.postDotMenu.replyMenuItem.click();
     await channelsPage.sidebarRight.toBeVisible();
@@ -71,6 +73,7 @@ test('MM-T5654_2 should be able to add attachments while editing a threaded post
     await replyPost.hover();
     await replyPost.postMenu.toBeVisible();
     await replyPost.postMenu.dotMenuButton.click();
+    await moveMouseAway(page);
     await channelsPage.postDotMenu.toBeVisible();
     await channelsPage.postDotMenu.editMenuItem.click();
     await channelsPage.sidebarRight.postEdit.toBeVisible();
@@ -85,6 +88,7 @@ test('MM-T5654_2 should be able to add attachments while editing a threaded post
     await updatedReplyPost.hover();
     await updatedReplyPost.postMenu.toBeVisible();
     await updatedReplyPost.postMenu.dotMenuButton.click();
+    await moveMouseAway(page);
     await channelsPage.postDotMenu.toBeVisible();
     await channelsPage.postDotMenu.editMenuItem.click();
     await channelsPage.sidebarRight.postEdit.toBeVisible();
@@ -103,7 +107,7 @@ test('MM-T5654_2 should be able to add attachments while editing a threaded post
     await updatedReplyPost.hover();
     await updatedReplyPost.postMenu.toBeVisible();
     await updatedReplyPost.postMenu.clickOnDotMenu();
-    await moveMouseToCenter(page);
+    await moveMouseAway(page);
     await channelsPage.postDotMenu.toBeVisible();
     await channelsPage.postDotMenu.editMenuItem.click();
     await channelsPage.sidebarRight.postEdit.toBeVisible();
@@ -124,7 +128,7 @@ test('MM-T5654_3 should be able to edit post message originally containing files
     const originalMessage = 'Lorem ipsum dolor sit amet, consectetur adipiscing elit';
 
     const {user} = await pw.initSetup();
-    const {channelsPage} = await pw.testBrowser.login(user);
+    const {channelsPage, page} = await pw.testBrowser.login(user);
 
     await channelsPage.goto();
     await channelsPage.toBeVisible();
@@ -137,6 +141,7 @@ test('MM-T5654_3 should be able to edit post message originally containing files
 
     // open the dot menu
     await post.postMenu.dotMenuButton.click();
+    await moveMouseAway(page);
     await channelsPage.postDotMenu.toBeVisible();
     await channelsPage.postDotMenu.editMenuItem.click();
     await channelsPage.centerView.postEdit.toBeVisible();
@@ -152,7 +157,7 @@ test('MM-T5654_4 should be able to add files when editing a post', async ({pw})
     const originalMessage = 'Lorem ipsum dolor sit amet, consectetur adipiscing elit';
 
     const {user} = await pw.initSetup();
-    const {channelsPage} = await pw.testBrowser.login(user);
+    const {channelsPage, page} = await pw.testBrowser.login(user);
 
     await channelsPage.goto();
     await channelsPage.toBeVisible();
@@ -165,6 +170,7 @@ test('MM-T5654_4 should be able to add files when editing a post', async ({pw})
 
     // open the dot menu
     await post.postMenu.dotMenuButton.click();
+    await moveMouseAway(page);
     await channelsPage.postDotMenu.toBeVisible();
     await channelsPage.postDotMenu.editMenuItem.click();
     await channelsPage.centerView.postEdit.toBeVisible();
@@ -179,6 +185,7 @@ test('MM-T5654_4 should be able to add files when editing a post', async ({pw})
 
     // now we'll add multiple files
     await post.postMenu.dotMenuButton.click();
+    await moveMouseAway(page);
     await channelsPage.postDotMenu.toBeVisible();
     await channelsPage.postDotMenu.editMenuItem.click();
     await channelsPage.centerView.postEdit.toBeVisible();
@@ -213,7 +220,7 @@ test('MM-5654_5 should be able to remove attachments while editing a post', asyn
     await post.hover();
     await post.postMenu.toBeVisible();
     await post.postMenu.clickOnDotMenu();
-    await moveMouseToCenter(page);
+    await moveMouseAway(page);
 
     await channelsPage.postDotMenu.toBeVisible();
     await channelsPage.postDotMenu.editMenuItem.click();
@@ -233,7 +240,7 @@ test('MM-T5655_1 removing message content and files should delete the post', asy
     const originalMessage = 'Lorem ipsum dolor sit amet, consectetur adipiscing elit';
 
     const {user} = await pw.initSetup();
-    const {channelsPage} = await pw.testBrowser.login(user);
+    const {channelsPage, page} = await pw.testBrowser.login(user);
 
     await channelsPage.goto();
     await channelsPage.toBeVisible();
@@ -247,6 +254,7 @@ test('MM-T5655_1 removing message content and files should delete the post', asy
     await post.hover();
     await post.postMenu.toBeVisible();
     await post.postMenu.dotMenuButton.click();
+    await moveMouseAway(page);
 
     await channelsPage.postDotMenu.toBeVisible();
     await channelsPage.postDotMenu.editMenuItem.click();
@@ -283,7 +291,7 @@ test('MM-T5655_2 should be able to remove all files when editing a post', async
     await post.hover();
     await post.postMenu.toBeVisible();
     await post.postMenu.clickOnDotMenu();
-    await moveMouseToCenter(page);
+    await moveMouseAway(page);
 
     await channelsPage.postDotMenu.toBeVisible();
     await channelsPage.postDotMenu.editMenuItem.click();
@@ -306,7 +314,7 @@ test('MM-T5656_1 should be able to restore previously edited post version that c
     const newMessage = 'New Message';
 
     const {user} = await pw.initSetup();
-    const {channelsPage} = await pw.testBrowser.login(user);
+    const {channelsPage, page} = await pw.testBrowser.login(user);
 
     await channelsPage.goto();
     await channelsPage.toBeVisible();
@@ -320,6 +328,7 @@ test('MM-T5656_1 should be able to restore previously edited post version that c
     await post.hover();
     await post.postMenu.toBeVisible();
     await post.postMenu.dotMenuButton.click();
+    await moveMouseAway(page);
 
     await channelsPage.postDotMenu.toBeVisible();
     await channelsPage.postDotMenu.editMenuItem.click();
@@ -350,6 +359,11 @@ test('MM-T5656_1 should be able to restore previously edited post version that c
     await restoredPost.toContainText('sample_text_file.txt');
 });
 
-async function moveMouseToCenter(page: Page) {
+/**
+ * Parks the cursor away from the post so it does not hover whatever menu item happens to render
+ * under it. A hovered submenu item (e.g. "Remind") opens a nested MUI popover, which marks the
+ * parent menu aria-hidden and makes getByRole('menu') unresolvable.
+ */
+async function moveMouseAway(page: Page) {
     await page.mouse.move(0, 0);
 }

server/channels/api4/post_test.go

@@ -996,6 +996,10 @@ func TestCreatePostWithOutgoingHook_no_content_type(t *testing.T) {
 }
 
 func TestMoveThread(t *testing.T) {
+	// Skipped: MoveThreadsEnabled is retired and rejected by Config.IsValid (MM-69646).
+	// This test requires the flag and cannot run while the server refuses to enable it.
+	t.Skip("MoveThreadsEnabled feature flag is retired (MM-69646)")
+
 	th := SetupEnterprise(t).InitBasic(t)
 
 	// Enable MoveThreads feature flag

server/i18n/en.json

@@ -11962,6 +11962,10 @@
     "id": "model.config.is_valid.extract_content_timeout.app_error",
     "translation": "Invalid content extraction timeout for file settings. Must be a whole number of seconds greater than or equal to zero."
   },
+  {
+    "id": "model.config.is_valid.feature_flags.move_threads_enabled.app_error",
+    "translation": "The MoveThreadsEnabled feature flag is no longer supported and must be disabled."
+  },
   {
     "id": "model.config.is_valid.file_driver.app_error",
     "translation": "Invalid driver name for file settings. Must be 'local', 'amazons3', or 'azureblob'."

server/public/model/config.go

@@ -4519,6 +4519,12 @@ func (o *Config) IsValid() *AppError {
 		return appErr
 	}
 
+	if o.FeatureFlags != nil {
+		if appErr := o.FeatureFlags.isValid(); appErr != nil {
+			return appErr
+		}
+	}
+
 	return nil
 }
 

server/public/model/config_test.go

@@ -116,6 +116,39 @@ func TestConfigIsValid(t *testing.T) {
 	})
 }
 
+func TestFeatureFlagsIsValid(t *testing.T) {
+	t.Run("defaults are valid", func(t *testing.T) {
+		f := &FeatureFlags{}
+		f.SetDefaults()
+		require.Nil(t, f.isValid())
+	})
+
+	t.Run("MoveThreadsEnabled is rejected", func(t *testing.T) {
+		f := &FeatureFlags{}
+		f.SetDefaults()
+		f.MoveThreadsEnabled = true
+
+		appErr := f.isValid()
+		require.NotNil(t, appErr)
+		require.Equal(t, "model.config.is_valid.feature_flags.move_threads_enabled.app_error", appErr.Id)
+	})
+}
+
+func TestConfigIsValidMoveThreadsEnabled(t *testing.T) {
+	c := Config{}
+	c.SetDefaults()
+	require.Nil(t, c.IsValid())
+
+	c.FeatureFlags.MoveThreadsEnabled = true
+	appErr := c.IsValid()
+	require.NotNil(t, appErr)
+	require.Equal(t, "model.config.is_valid.feature_flags.move_threads_enabled.app_error", appErr.Id)
+
+	// A nil FeatureFlags must not panic the validation chain.
+	c.FeatureFlags = nil
+	require.Nil(t, c.IsValid())
+}
+
 func TestAccessControlSettingsIsValid(t *testing.T) {
 	for name, test := range map[string]struct {
 		AccessControlSettings AccessControlSettings

server/public/model/feature_flags.go

@@ -4,6 +4,7 @@
 package model
 
 import (
+	"net/http"
 	"reflect"
 	"strconv"
 )
@@ -219,6 +220,17 @@ func (f *FeatureFlags) SetDefaults() {
 	f.RecurringScheduledPosts = false
 }
 
+// isValid rejects feature flag combinations that are no longer supported.
+func (f *FeatureFlags) isValid() *AppError {
+	// MoveThreadsEnabled is being retired in favor of Wrangler, so the server
+	// refuses to start while it is enabled.
+	if f.MoveThreadsEnabled {
+		return NewAppError("FeatureFlags.IsValid", "model.config.is_valid.feature_flags.move_threads_enabled.app_error", nil, "", http.StatusBadRequest)
+	}
+
+	return nil
+}
+
 // IsChannelPermissionPoliciesEnabled reports whether channel-scope
 // policies may carry permission-rule actions (file upload/download)
 // and whether the Channel Settings → Permissions Policy tab should