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TUI black-screen hang mid-turn in 1.0.70-0 (Windows Terminal); content intact, recoverable via --resume #4077

Description

@dmauser

Describe the bug

Environment:

  • CLI version: 1.0.70-0 (pre-release; auto-updated ahead of npm stable 1.0.69-1)
  • Install: WinGet (GitHub.Copilot), self-updating pkg in %LOCALAPPDATA%\copilot\pkg\win32-x64
  • OS: Windows 11, Windows Terminal
  • Node: v24.15.0
  • Extensions loaded: network-desk https://github.com/dmauser/network-desk

Symptom:
After a few prompts, the ENTIRE terminal viewport goes black and input freezes mid-turn.
The alt-screen renderer stops painting; keyboard input (Ctrl+L, Ctrl+O, Ctrl+C, resize)
does not recover the view. The tab still auto-titles from the response, so the backend
is producing output — only the live TUI is frozen.

Impact / proof content is intact:
Closing the terminal and running copilot --resume shows the FULL response for the
hung turn. No data loss — this is purely a client-side rendering/hang regression.
Logs show content_filter=0 and refusal=null, so it is not content filtering.

Regression window:
Started immediately after auto-update to 1.0.70-0. Earlier cached builds
(1.0.68 / 1.0.67) launched via --prefer-version do not exhibit the hang.

Workaround:
copilot --prefer-version 1.0.68 (pins a good cached build and disables auto-update).
Recovery from a hung session: copilot --resume.

Suspected area:
Interactive alt-screen TUI renderer (enterAltScreen path) in 1.0.70-0.
Possibly aggravated by large per-turn additionalContext from an extension, but the
hang is the client renderer, not the model output.

Affected version

GitHub Copilot CLI 1.0.70-0

Steps to reproduce the behavior

  1. Install extension using:
    npx github:dmauser/network-desk init
  2. run copilot in experimental mode:
    copilot --experimental
  3. Type on the copilot prompt:
    @network-desk what are your capabilities?
    We get the blank screen and it becomes unresponsive.
  4. Kill the session and run
    copilot --experimental --resume
  5. Pick the one named: Explore Network Desk Capabilities.

Expected behavior

The expected behavior is to get the answer on the same session screen without get the hang.

Additional context

No response

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    area:platform-windowsWindows-specific: PowerShell, cmd, Git Bash, WSL, Windows Terminalarea:terminal-renderingDisplay and rendering: flickering, scrolling, line wrapping, output formatting

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