disable burn on read posts on shared channels (#35460)

server/channels/app/post_permission_utils.go

@@ -142,6 +142,10 @@ func PostBurnOnReadCheckWithApp(where string, a *App, rctx request.CTX, userId,
 		channel = ch
 	}
 
+	if channel.IsShared() {
+		return model.NewAppError(where, "api.post.fill_in_post_props.burn_on_read.shared_channel.app_error", nil, "", http.StatusBadRequest)
+	}
+
 	// Burn-on-read is not allowed in self-DMs or DMs with bots (including AI agents, plugins)
 	if channel.Type == model.ChannelTypeDirect {
 		// Check if it's a self-DM by comparing the channel name with the expected self-DM name

server/channels/app/post_test.go

@@ -1371,6 +1371,70 @@ func TestCreatePost(t *testing.T) {
 		require.Nil(t, appErr)
 		require.Empty(t, createdPost.FileIds)
 	})
+
+	t.Run("should reject burn-on-read posts in shared channels", func(t *testing.T) {
+		os.Setenv("MM_FEATUREFLAGS_BURNONREAD", "true")
+		t.Cleanup(func() {
+			os.Unsetenv("MM_FEATUREFLAGS_BURNONREAD")
+		})
+		th := setupSharedChannels(t).InitBasic(t)
+		enableBoRFeature(th)
+
+		channel := th.CreateChannel(t, th.BasicTeam)
+
+		sc := &model.SharedChannel{
+			ChannelId: channel.Id,
+			TeamId:    th.BasicTeam.Id,
+			Type:      channel.Type,
+			Home:      true,
+			ShareName: "shared-bor-test",
+			CreatorId: th.BasicUser.Id,
+			RemoteId:  model.NewId(),
+		}
+		_, scErr := th.Server.Store().SharedChannel().Save(sc)
+		require.NoError(t, scErr)
+
+		channel.Shared = model.NewPointer(true)
+		_, err := th.Server.Store().Channel().Update(th.Context, channel)
+		require.NoError(t, err)
+
+		post := &model.Post{
+			ChannelId: channel.Id,
+			UserId:    th.BasicUser.Id,
+			Message:   "burn-on-read in shared channel",
+			Type:      model.PostTypeBurnOnRead,
+		}
+
+		createdPost, _, appErr := th.App.CreatePost(th.Context, post, channel, model.CreatePostFlags{SetOnline: true})
+		require.NotNil(t, appErr)
+		require.Nil(t, createdPost)
+		require.Equal(t, "api.post.fill_in_post_props.burn_on_read.shared_channel.app_error", appErr.Id)
+		require.Equal(t, http.StatusBadRequest, appErr.StatusCode)
+	})
+
+	t.Run("should allow burn-on-read posts in non-shared channels", func(t *testing.T) {
+		os.Setenv("MM_FEATUREFLAGS_BURNONREAD", "true")
+		t.Cleanup(func() {
+			os.Unsetenv("MM_FEATUREFLAGS_BURNONREAD")
+		})
+		th := Setup(t).InitBasic(t)
+		enableBoRFeature(th)
+
+		channel := th.CreateChannel(t, th.BasicTeam)
+		require.False(t, channel.IsShared())
+
+		post := &model.Post{
+			ChannelId: channel.Id,
+			UserId:    th.BasicUser.Id,
+			Message:   "burn-on-read in non-shared channel",
+			Type:      model.PostTypeBurnOnRead,
+		}
+
+		createdPost, _, appErr := th.App.CreatePost(th.Context, post, channel, model.CreatePostFlags{SetOnline: true})
+		require.Nil(t, appErr)
+		require.NotNil(t, createdPost)
+		require.Equal(t, model.PostTypeBurnOnRead, createdPost.Type)
+	})
 }
 
 func TestPatchPost(t *testing.T) {

server/i18n/en.json

@@ -2868,6 +2868,10 @@
     "id": "api.post.fill_in_post_props.burn_on_read.self_dm.app_error",
     "translation": "Burn-on-read posts are not allowed when messaging yourself."
   },
+  {
+    "id": "api.post.fill_in_post_props.burn_on_read.shared_channel.app_error",
+    "translation": "Burn-on-read posts are not allowed in shared channels."
+  },
   {
     "id": "api.post.fill_in_post_props.burn_on_read.user.app_error",
     "translation": "An error occurred while validating the user for burn-on-read post."

webapp/channels/src/components/advanced_text_editor/use_burn_on_read.test.tsx

@@ -215,6 +215,42 @@ describe('useBurnOnRead', () => {
 
             expect(result.current.additionalControl).toBeDefined();
         });
+
+        it('should hide burn-on-read button in shared channels', () => {
+            const sharedChannel = {...createMockChannel('O'), shared: true};
+            (getChannel as jest.Mock).mockReturnValue(sharedChannel);
+
+            const {result} = renderHook(
+                () => useBurnOnRead(
+                    createMockDraft(),
+                    mockHandleDraftChange,
+                    mockFocusTextbox,
+                    false,
+                    true,
+                ),
+                {wrapper},
+            );
+
+            expect(result.current.additionalControl).toBeUndefined();
+        });
+
+        it('should show burn-on-read button in non-shared channels', () => {
+            const nonSharedChannel = {...createMockChannel('O'), shared: false};
+            (getChannel as jest.Mock).mockReturnValue(nonSharedChannel);
+
+            const {result} = renderHook(
+                () => useBurnOnRead(
+                    createMockDraft(),
+                    mockHandleDraftChange,
+                    mockFocusTextbox,
+                    false,
+                    true,
+                ),
+                {wrapper},
+            );
+
+            expect(result.current.additionalControl).toBeDefined();
+        });
     });
 
     describe('button visibility with feature flags', () => {

webapp/channels/src/components/advanced_text_editor/use_burn_on_read.tsx

@@ -79,6 +79,10 @@ const useBurnOnRead = (
             }
         }
 
+        if (channel.shared) {
+            return false;
+        }
+
         return true; // Allow all other channel types
     }, [channel, currentUser, otherUser]);