[Bug]: Main thread freeze when opening a channel - ChannelUpdater.cleanStaleMidPageStateIfNeeded blocks on performAndWait

[denis-obukhov]

Actual behaviour

SDK version: stream-chat-swift / stream-chat-swiftui 5.5.1
Swift: 6 / strict concurrency enabled

When I open a channel, the app freezes for a few seconds. Time Profiler shows the main thread blocked inside:

ChannelUpdater.cleanStaleMidPageStateIfNeeded(for:isInRecoveryMode:)
  └─ writableContext.performAndWait { ... }
       └─ channelDTO.cleanAllMessagesExcludingLocalOnly()
       └─ writableContext.save()

This runs synchronously at the start of ChannelUpdater.update(), which is called from ChatChannelController.synchronize(). Since synchronize() is @mainactor and ChatChannelViewModel calls it in init, the UI thread blocks until Core Data finishes.

Everything worked flawlessly on version 4.97.0.
On v5.1.0 it was better than on v5.2.0
Unfortunately, starting from version 5.2.0, the app has become extremely problematic

Expected behaviour

Opening a channel should feel instant.

Steps to reproduce

Connect a user with a non-trivial inbox (many channels, some with long history).
Open a channel
Navigate back to the channel list.
Open the same/other channel again.

Which packages are you using?

No response

Which SDK version are you using?

5.5.1

Which iOS version is the issue reproducible?

iOS 26.3, 26.4, 26.5

Which iPhone Device is the issue reproducible?

Any

Which Xcode version are you using?

Xcode 26.2

[nuno-vieira]

Hi @denis-obukhov,

We can't reproduce this in our Demo App. Do you have any customizations? Are you able to reproduce this with our Demo App?

Can you share your code on how you are opening a channel?

Best,
Nuno

[nuno-vieira]

Closing this one for inactivity. Feel free to open it again if you are still having issues.

Best,
Nuno