Fix ui deadlock#182
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Pull request overview
Fixes the chat UI deadlock that could permanently freeze Eclipse when a 402 quota error triggers model fallback handling, and adds guards to prevent an infinite 402 retry loop. It also improves turn rendering so model info isn’t duplicated and stays positioned correctly when warnings are added.
Changes:
- Make model preference persistence asynchronous to avoid blocking the UI thread during fallback switching.
- Prevent infinite 402 fallback retry loops by detecting when the fallback model is already active and adjusting messaging accordingly.
- Ensure the model info footer in a Copilot turn is replaced (not duplicated) and remains below warning widgets.
Reviewed changes
Copilot reviewed 3 out of 3 changed files in this pull request and generated 3 comments.
| File | Description |
|---|---|
| com.microsoft.copilot.eclipse.ui/src/com/microsoft/copilot/eclipse/ui/chat/services/ModelService.java | Persists model preference asynchronously to break the UI-thread ↔ LSP-listener deadlock chain. |
| com.microsoft.copilot.eclipse.ui/src/com/microsoft/copilot/eclipse/ui/chat/ChatContentViewer.java | Adds “already on fallback” guard to avoid infinite 402 retry/switch loops and conditionally replaces the 402 message. |
| com.microsoft.copilot.eclipse.ui/src/com/microsoft/copilot/eclipse/ui/chat/CopilotTurnWidget.java | Prevents duplicate model info labels and forces footer ordering below warning widgets. |
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xinyi-gong
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ethanyhou
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May 13, 2026
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ethanyhou
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ethanyhou
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Verified and LGTM, thanks!
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fix #179
Problem
When a 402 quota error occurs during chat, the UI freezes permanently due to a deadlock between the main thread and the LSP listener thread.
Deadlock chain:
processTurnEvent()→ blocks inDisplay.syncExec()waiting for UI threadsetFallBackModelAsActiveModel()→persistUserPreference()→persistence().get()blocks waiting for LSP responsesyncExec→ the persistence response can never arriveChanges
ModelService.javapersistUserPreference()is now called asynchronously viaCompletableFuture.runAsync()insetActiveModel(), breaking the deadlock chain by keeping the UI thread unblocked.