🔁 Terminal panel resizing causes repeated or duplicate output rendering

[abedin-bd]

Bug Description

When resizing the integrated terminal panel in VS Code (by dragging the top edge up/down), log output from running scripts appears to be re-printed or duplicated unexpectedly.

However, if the user simply clicks the small “Restore Panel Size” arrow (in the top-right of the terminal), the issue does not occur — output remains clean.

This suggests the terminal is re-flushing buffer or misrendering logs during manual resize operations.

---

Steps to Reproduce

1. Open any workspace with an integrated terminal
2. Run the following long-running script:

   import time
   for i in range(10):
       print(f"Log entry: {i}")
       time.sleep(1)

3. While the script is running, drag the terminal panel height up and down
4. Observe that lines repeat or redraw multiple times

🔁 Now try this instead:

• Click the “Restore Panel Size” arrow button in the terminal header
• The logs do not repeat, and output stays clean

---

Expected Behavior

• Resizing terminal should not cause duplicate output
• Log output should be flushed only once per execution

---

Actual Behavior

• Output appears to repeat or re-render when resizing panel
• Clicking “Restore Panel Size” avoids the issue

---

Environment

• VS Code Version: 1.88.x (or latest)
• OS: Windows 10/11
• Shells Tested: PowerShell, CMD
• Extensions: Tested with all disabled
• Python Version: [your Python version here]

---

Impact

This issue makes terminal logs noisy, especially during background script execution, and can be misleading during debugging or output analysis.

Please investigate this UI interaction and its effect on stdout handling during terminal redraws.

[vs-code-engineering]

Thanks for creating this issue! It looks like you may be using an old version of VS Code, the latest stable release is 1.99.3. Please try upgrading to the latest version and checking whether this issue remains.

Happy Coding!

[abedin-bd]

Version: 1.99.3 (user setup)
Commit: 17baf84
Date: 2025-04-15T23:18:46.076Z
Electron: 34.3.2
ElectronBuildId: 11161073
Chromium: 132.0.6834.210
Node.js: 20.18.3
V8: 13.2.152.41-electron.0
OS: Windows_NT x64 10.0.19045

[meganrogge]

This issue seems to originate from an upstream component and is not something VSCode can fix by making a change to our code. As such, I will go ahead and close it. Please try to reproduce in Windows Terminal and report to microsoft/terminal with repro steps.

If you cannot reproduce in Windows Terminal, chances are it's fixed in a later version of Windows. You can read more about how we consume conpty here. Thanks for understanding.

/label upstream terminal-conpty windows