Profile: the music strip arrives with the transition

The header showed the profile's saved-music list only, and the list context
publishes an empty loading state at once, so the full user's track (which the
chat has usually fetched already) was ignored until the list answered. On a
first open that is the network: the strip was missing from the first layout,
and when it landed during the chat-to-profile expansion the held layout was
applied without animation as the transition ended, snapping the strip and the
24 pt header growth in one frame.

- Until the list answers, the strip shows the full user's track
  (peerInfoProfileMusic, tested); a list that answers empty shows none.
- The strip arriving or leaving counts as an info change in updateData, so a
  late arrival animates.
- A strip change while the views are lent to an expansion is applied with the
  same spring when they come back.
- Tapping the strip before the list answers waits for it, since the player
  plays the list.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Author: isaac

submodules/TelegramUI/Components/PeerInfo/PeerInfoPaneNode/Sources/PeerInfoProfileMusic.swift

@@ -0,0 +1,16 @@
+import Foundation
+
+/// The track a profile's music strip shows: the first of the profile's saved-music list (`list`, nil where the screen
+/// has none). While that list has not answered (loading with nothing in it, before its cache or the server replies:
+/// a profile opened for the first time), the full user's track (`CachedUserData.savedMusic`), which the chat has usually
+/// fetched already, so the strip is in the profile's first layout and arrives with the transition instead of after it.
+/// A list that answered empty shows none, whatever the full user still says.
+public func peerInfoProfileMusic<File>(list: (files: [File], isLoading: Bool)?, fullUserMusic: File?) -> File? {
+    guard let list else {
+        return fullUserMusic
+    }
+    if let first = list.files.first {
+        return first
+    }
+    return list.isLoading ? fullUserMusic : nil
+}

submodules/TelegramUI/Components/PeerInfo/PeerInfoPaneNode/Tests/PeerInfoProfileMusicTests.swift

@@ -0,0 +1,27 @@
+import XCTest
+@testable import PeerInfoPaneNode
+
+final class PeerInfoProfileMusicTests: XCTestCase {
+    // The list's first track once it has one, loading or not.
+    func test_listTrack() {
+        XCTAssertEqual(peerInfoProfileMusic(list: (files: [1, 2], isLoading: false), fullUserMusic: 3), 1)
+        XCTAssertEqual(peerInfoProfileMusic(list: (files: [1, 2], isLoading: true), fullUserMusic: 3), 1)
+    }
+
+    // A list that has not answered yet: the full user's track, so the strip is there from the first layout.
+    func test_loadingListFallsBackToFullUser() {
+        XCTAssertEqual(peerInfoProfileMusic(list: (files: [Int](), isLoading: true), fullUserMusic: 3), 3)
+        XCTAssertNil(peerInfoProfileMusic(list: (files: [Int](), isLoading: true), fullUserMusic: nil))
+    }
+
+    // A list that answered empty: none, even while the full user still carries a track.
+    func test_answeredEmptyListShowsNone() {
+        XCTAssertNil(peerInfoProfileMusic(list: (files: [Int](), isLoading: false), fullUserMusic: 3))
+    }
+
+    // No list on the screen: the full user's track.
+    func test_noList() {
+        XCTAssertEqual(peerInfoProfileMusic(list: nil, fullUserMusic: 3), 3)
+        XCTAssertNil(peerInfoProfileMusic(list: nil as (files: [Int], isLoading: Bool)?, fullUserMusic: nil))
+    }
+}

submodules/TelegramUI/Components/PeerInfo/PeerInfoScreen/Sources/PeerInfoHeaderNode.swift

@@ -196,6 +196,18 @@ final class PeerInfoHeaderNode: ASDisplayNode {
     var hasBottomStrip: Bool {
         return self.music != nil
     }
+
+    /// The track the music strip shows for `peer` and `screenData` (`peerInfoProfileMusic`): none on Settings and on the
+    /// account's own peer opened as a profile.
+    func profileMusic(peer: EnginePeer?, screenData: PeerInfoScreenData?) -> TelegramMediaFile? {
+        guard let peer, peer.id != self.context.account.peerId || self.isMyProfile, let screenData else {
+            return nil
+        }
+        let list = screenData.savedMusicState.map { state -> (files: [TelegramMediaFile], isLoading: Bool) in
+            return (state.files, state.dataState == .loading)
+        }
+        return peerInfoProfileMusic(list: list, fullUserMusic: (screenData.cachedData as? CachedUserData)?.savedMusic)
+    }
 
     var performButtonAction: ((PeerInfoHeaderButtonKey, PeerInfoHeaderButtonNode?, ContextGesture?) -> Void)?
     var requestAvatarExpansion: ((Bool, [AvatarGalleryEntry], AvatarGalleryEntry?, (ASDisplayNode, CGRect, () -> (UIView?, UIView?))?) -> Void)?
@@ -622,14 +634,7 @@ final class PeerInfoHeaderNode: ASDisplayNode {
             backgroundCoverSubject = nil
         }
 
-        var currentSavedMusic: TelegramMediaFile?
-        if let peer, peer.id != self.context.account.peerId || self.isMyProfile, let screenData {
-            if let savedMusicState = screenData.savedMusicState {
-                currentSavedMusic = savedMusicState.files.first
-            } else if let cachedUserData = screenData.cachedData as? CachedUserData {
-                currentSavedMusic = cachedUserData.savedMusic
-            }
-        }
+        let currentSavedMusic = self.profileMusic(peer: peer, screenData: screenData)
         let currentWalletBalance: Int64?
         if !self.isSettings, let balance = (screenData?.cachedData as? CachedUserData)?.walletCard?.balance, balance >= 100_000_000 {
             currentWalletBalance = balance

submodules/TelegramUI/Components/PeerInfo/PeerInfoScreen/Sources/PeerInfoScreen.swift

@@ -273,6 +273,7 @@ final class PeerInfoScreenNode: ViewControllerTracingNode, PeerInfoScreenNodePro
     var resolvePeerByNameDisposable: MetaDisposable?
     let navigationActionDisposable = MetaDisposable()
     let enqueueMediaMessageDisposable = MetaDisposable()
+    private let openSavedMusicDisposable = MetaDisposable()
 
     private(set) var validLayout: (ContainerViewLayout, CGFloat)?
     /// While an expansion has the profile's views they are held still: layouts wait, and the last one is applied when
@@ -2701,6 +2702,7 @@ final class PeerInfoScreenNode: ViewControllerTracingNode, PeerInfoScreenNodePro
         self.resolvePeerByNameDisposable?.dispose()
         self.navigationActionDisposable.dispose()
         self.enqueueMediaMessageDisposable.dispose()
+        self.openSavedMusicDisposable.dispose()
         self.supportPeerDisposable.dispose()
         self.tipsPeerDisposable.dispose()
         self.shareStatusDisposable?.dispose()
@@ -2920,6 +2922,10 @@ final class PeerInfoScreenNode: ViewControllerTracingNode, PeerInfoScreenNodePro
                 if (previousBusinessLocation == nil) != (currentBusinessLocation != nil) {
                     infoUpdated = true
                 }
+                // The music strip arriving or leaving changes the header's height, and the page moves with it.
+                if self.hasProfileMusic(data: previousData) != self.hasProfileMusic(data: data) {
+                    infoUpdated = true
+                }
             }
 
             self.containerLayoutUpdated(layout: layout, navigationHeight: navigationHeight, transition: self.didSetReady && (membersUpdated || infoUpdated) ? .animated(duration: 0.3, curve: .spring) : .immediate)
@@ -3088,6 +3094,10 @@ final class PeerInfoScreenNode: ViewControllerTracingNode, PeerInfoScreenNodePro
         }
     }
 
+    private func hasProfileMusic(data: PeerInfoScreenData?) -> Bool {
+        return self.headerNode.profileMusic(peer: data?.savedMessagesPeer ?? data?.peer, screenData: data) != nil
+    }
+
     var previousSavedMusicTimestamp: Double?
     private func displaySavedMusic() {
         guard let savedMusicContext = self.data?.savedMusicContext else {
@@ -3100,15 +3110,21 @@ final class PeerInfoScreenNode: ViewControllerTracingNode, PeerInfoScreenNodePro
         }
         self.previousSavedMusicTimestamp = currentTimestamp
 
-        let _ = (self.context.sharedContext.mediaManager.globalMediaPlayerState
+        // Until the list answers, the strip shows the full user's track (`peerInfoProfileMusic`); the player plays the
+        // list, so it waits for it.
+        let answeredList = savedMusicContext.state
+        |> filter { state in
+            return !state.files.isEmpty || state.dataState != .loading
+        }
         |> take(1)
-        |> deliverOnMainQueue).start(next: { [weak self] accountStateAndType in
+        self.openSavedMusicDisposable.set((combineLatest(answeredList, self.context.sharedContext.mediaManager.globalMediaPlayerState |> take(1))
+        |> deliverOnMainQueue).start(next: { [weak self] listState, accountStateAndType in
             guard let self else {
                 return
             }
             let peerId = self.peerId
             var initialId: Int32
-            if let initialFileId = self.data?.savedMusicState?.files.first?.fileId {
+            if let initialFileId = listState.files.first?.fileId {
                 initialId = Int32(clamping: initialFileId.id % Int64(Int32.max))
             } else {
                 initialId = 0
@@ -3139,7 +3155,7 @@ final class PeerInfoScreenNode: ViewControllerTracingNode, PeerInfoScreenNodePro
                 musicController.navigationPresentation = .flatModal
                 self.controller?.push(musicController)
             }
-        })
+        }))
     }
 
     func openAutoremove(currentValue: Int32?) {
@@ -5568,7 +5584,10 @@ final class PeerInfoScreenNode: ViewControllerTracingNode, PeerInfoScreenNodePro
         self.contentOffsetWhenLent = nil
         if let held = self.layoutHeldDuringExpansion ?? self.validLayout.flatMap({ (layout: $0.0, navigationHeight: $0.1) }) {
             self.layoutHeldDuringExpansion = nil
-            self.containerLayoutUpdated(layout: held.layout, navigationHeight: held.navigationHeight, transition: .immediate)
+            // The music strip arrived or left while the views were lent (the header still has what it had when they were
+            // lent): it moves in as it does outside an expansion, instead of appearing in one frame.
+            let stripChanged = self.headerNode.hasBottomStrip != self.hasProfileMusic(data: self.data)
+            self.containerLayoutUpdated(layout: held.layout, navigationHeight: held.navigationHeight, transition: stripChanged ? .animated(duration: 0.3, curve: .spring) : .immediate)
         }
         let actions = self.actionsAfterExpansion
         self.actionsAfterExpansion = []