Display an icon in the room header for rooms with shared history (#5016)

* feat: Display an icon in the room header for rooms with shared history

* fix: Apply suggestions from code review

- Simplifies `isRoomHistoryShared` expressions using type inferrence.
- Adds failure messages to unit test.

Co-authored-by: Doug <6060466+pixlwave@users.noreply.github.com>

* fix: Remove extension method in favour of field on configuration.

* fix: Distinguish between `shared` and `worldReadable` icons.

* refactor: Use `RoomHistorySharingState` enum with extension methods

---------

Co-authored-by: Doug <6060466+pixlwave@users.noreply.github.com>

ElementX/Sources/Mocks/JoinedRoomProxyMock.swift

@@ -27,6 +27,7 @@ struct JoinedRoomProxyMockConfiguration {
     var canonicalAlias: String?
     var alternativeAliases: [String] = []
     var pinnedEventIDs: Set<String> = []
+    var historyVisibility: RoomHistoryVisibility = .shared
     
     var timelineStartReached = false
     
@@ -190,7 +191,7 @@ extension RoomInfoProxyMock {
         unreadMentionsCount = 0
         pinnedEventIDs = configuration.pinnedEventIDs
         joinRule = configuration.joinRule
-        historyVisibility = .shared
+        historyVisibility = configuration.historyVisibility
         
         powerLevels = RoomPowerLevelsProxyMock(configuration: configuration.powerLevelsConfiguration)
     }

ElementX/Sources/Other/SwiftUI/Views/RoomHeaderView.swift

@@ -15,6 +15,7 @@ struct RoomHeaderView: View {
     var roomSubtitle: String?
     let roomAvatar: RoomAvatar
     var dmRecipientVerificationState: UserIdentityVerificationState?
+    var roomHistorySharingState: RoomHistorySharingState?
     
     let mediaProvider: MediaProviderProtocol?
     
@@ -63,6 +64,11 @@ struct RoomHeaderView: View {
                 if let dmRecipientVerificationState {
                     VerificationBadge(verificationState: dmRecipientVerificationState, size: .xSmall, relativeTo: .compound.bodyMDSemibold)
                 }
+                
+                if let historySharingIcon {
+                    CompoundIcon(historySharingIcon, size: .xSmall, relativeTo: .compound.bodyMDSemibold)
+                        .foregroundStyle(.compound.iconInfoPrimary)
+                }
             }
         }
     }
@@ -73,6 +79,14 @@ struct RoomHeaderView: View {
                         mediaProvider: mediaProvider)
             .accessibilityIdentifier(A11yIdentifiers.roomScreen.avatar)
     }
+    
+    private var historySharingIcon: KeyPath<CompoundIcons, Image>? {
+        switch roomHistorySharingState {
+        case .shared: \.history
+        case .worldReadable: \.userProfileSolid
+        case .none: nil
+        }
+    }
 }
 
 extension RoomHeaderView {
@@ -106,19 +120,26 @@ struct RoomHeaderView_Previews: PreviewProvider, TestablePreview {
             makeHeader(avatarURL: .mockMXCAvatar,
                        roomSubtitle: "Subtitle",
                        verificationState: .verified)
+            makeHeader(avatarURL: .mockMXCAvatar, verificationState: .notVerified, historySharingState: .shared)
+            makeHeader(avatarURL: .mockMXCAvatar, verificationState: .notVerified, historySharingState: .worldReadable)
+            makeHeader(avatarURL: .mockMXCAvatar, verificationState: .verified, historySharingState: .shared)
+            makeHeader(avatarURL: .mockMXCAvatar, verificationState: .verificationViolation, historySharingState: .worldReadable)
         }
         .previewLayout(.sizeThatFits)
     }
     
     static func makeHeader(avatarURL: URL?,
                            roomSubtitle: String? = nil,
-                           verificationState: UserIdentityVerificationState) -> some View {
+                           verificationState: UserIdentityVerificationState,
+                           historySharingState: RoomHistorySharingState? = nil) -> some View {
         RoomHeaderView(roomName: "Some Room name",
                        roomSubtitle: roomSubtitle,
                        roomAvatar: .room(id: "1",
                                          name: "Some Room Name",
                                          avatarURL: avatarURL),
                        dmRecipientVerificationState: verificationState,
+                       roomHistorySharingState: historySharingState,
+                       
                        mediaProvider: MediaProviderMock(configuration: .init())) { }
             .padding()
     }

ElementX/Sources/Screens/RoomScreen/RoomScreenModels.swift

@@ -7,6 +7,7 @@
 //
 
 import Foundation
+import MatrixRustSDK
 import OrderedCollections
 
 enum RoomScreenViewModelAction: Equatable {
@@ -80,6 +81,9 @@ struct RoomScreenViewState: BindableState {
             (canAcceptKnocks || canDeclineKnocks || canBan)
     }
     
+    /// If `enableKeyShareOnInvite` is set, determines the current history sharing state.
+    var roomHistorySharingState: RoomHistorySharingState?
+    
     var footerDetails: RoomScreenFooterViewDetails?
     
     var bindings = RoomScreenViewStateBindings()

ElementX/Sources/Screens/RoomScreen/RoomScreenViewModel.swift

@@ -67,10 +67,17 @@ class RoomScreenViewModel: RoomScreenViewModelType, RoomScreenViewModelProtocol
         self.initialSelectedPinnedEventID = initialSelectedPinnedEventID
         pinnedEventStringBuilder = .pinnedEventStringBuilder(userID: roomProxy.ownUserID)
 
+        let roomHistorySharingState: RoomHistorySharingState? = if appSettings.enableKeyShareOnInvite {
+            roomProxy.infoPublisher.value.historySharingState
+        } else {
+            nil
+        }
+        
         let viewState = RoomScreenViewState(roomTitle: roomProxy.infoPublisher.value.displayName ?? roomProxy.id,
                                             roomAvatar: roomProxy.infoPublisher.value.avatar,
                                             hasOngoingCall: roomProxy.infoPublisher.value.hasRoomCall,
-                                            hasSuccessor: roomProxy.infoPublisher.value.successor != nil)
+                                            hasSuccessor: roomProxy.infoPublisher.value.successor != nil,
+                                            roomHistorySharingState: roomHistorySharingState)
         super.init(initialViewState: appHooks.roomScreenHook.update(viewState),
                    mediaProvider: userSession.mediaProvider)
         
@@ -342,6 +349,14 @@ class RoomScreenViewModel: RoomScreenViewModelType, RoomScreenViewModelProtocol
             state.canDeclineKnocks = powerLevels.canOwnUserKick()
             state.canBan = powerLevels.canOwnUserBan()
         }
+        
+        // This causes the UI to become inconsistent with the user's mental model if the user
+        // does not restart the app after disabling the feature flag. We can probably ignore
+        // such cases, since we explicitly ask for an app restart in the caption of the feature
+        // flag switch.
+        if appSettings.enableKeyShareOnInvite {
+            state.roomHistorySharingState = roomInfo.historySharingState
+        }
     }
     
     private func setupPinnedEventsTimelineItemProviderIfNeeded() {

ElementX/Sources/Screens/RoomScreen/View/RoomScreen.swift

@@ -157,6 +157,7 @@ struct RoomScreen: View {
             RoomHeaderView(roomName: context.viewState.roomTitle,
                            roomAvatar: context.viewState.roomAvatar,
                            dmRecipientVerificationState: context.viewState.dmRecipientVerificationState,
+                           roomHistorySharingState: context.viewState.roomHistorySharingState,
                            mediaProvider: context.mediaProvider) {
                 context.send(viewAction: .displayRoomDetails)
             }

ElementX/Sources/Screens/ThreadTimelineScreen/ThreadTimelineScreenModels.swift

@@ -17,6 +17,7 @@ struct ThreadTimelineScreenViewState: BindableState {
     var roomAvatar: RoomAvatar
     var canSendMessage = true
     var dmRecipientVerificationState: UserIdentityVerificationState?
+    var roomHistorySharingState: RoomHistorySharingState?
     
     var bindings = ThreadTimelineScreenViewStateBindings()
 }

ElementX/Sources/Screens/ThreadTimelineScreen/View/ThreadTimelineScreen.swift

@@ -65,6 +65,7 @@ struct ThreadTimelineScreen: View {
                            roomSubtitle: context.viewState.roomTitle,
                            roomAvatar: context.viewState.roomAvatar,
                            dmRecipientVerificationState: context.viewState.dmRecipientVerificationState,
+                           roomHistorySharingState: context.viewState.roomHistorySharingState,
                            mediaProvider: context.mediaProvider) {
                 // There is no action but the iOS 26 designs have it looking like a button.
             }

ElementX/Sources/Services/Room/RoomHistorySharingState.swift

@@ -0,0 +1,15 @@
+//
+// Copyright 2026 Element Creations Ltd.
+//
+// SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial.
+// Please see LICENSE files in the repository root for full details.
+//
+
+/// Enumeration of the two possible cases in which history sharing under MSC4268 is enabled. These
+/// variants implicitly assume that the feature flag, `enableKeyShareOnInvite`, is set.
+enum RoomHistorySharingState: Equatable {
+    /// The feature flag is set, and the room history visibility is set to `shared`.
+    case shared
+    /// The feature flag is set, and the room history visibility is set to `world_readable`.
+    case worldReadable
+}

ElementX/Sources/Services/Room/RoomInfoProxyProtocol.swift

@@ -134,4 +134,20 @@ extension RoomInfoProxyProtocol {
         // And finally return whatever the first alternative alias is
         return alternativeAliases.first
     }
+    
+    /// If present, the state of history sharing in this room. This *does not* consider the `enableKeyShareOnInvite`
+    /// feature flag, so consumers should be careful to check the flag is true before utilising this property.
+    var historySharingState: RoomHistorySharingState? {
+        guard isEncrypted else {
+            return nil
+        }
+        return switch historyVisibility {
+        case .shared:
+            .shared
+        case .worldReadable:
+            .worldReadable
+        default:
+            nil
+        }
+    }
 }