VSCode Copilot Agent causes .ipynb cell content to disappear after edits — rendering failure in Notebook editor

[Broderick-23]

🧩 Problem Summary

When using GitHub Copilot Agent to modify code in .ipynb (Jupyter Notebook) files, the edited cell becomes completely blank — no code is shown, and the cell cannot be interacted with.
This occurs regardless of the model used (GPT-4, GPT-4o, Claude 3.5/4). The issue seems to be related to VSCode’s Notebook rendering breaking after Agent edits.

---

❗ Symptoms

• After code is generated or modified by Copilot Agent in a .ipynb file:

  • The target cell displays only a colored block (no code, no cursor, no interactivity).
  • Accept/Discard edit controls do not appear.
  • The cell cannot be edited, selected, or recovered.
  • Other cells remain normal.

• Restarting VSCode or reloading the window sometimes temporarily restores the cell, but re-editing causes the issue again.

---

✅ Environment Info

Component	Version/Detail
VSCode Version	1.102.2 (user setup)
Github Copilot	1.346.0
OS	Windows_NT x64 10.0.22631
Python Extension	2025.10.1
Notebook Extension	2025.6.0
Terminal	Microsoft Windows 10.0.22631.5472
Agent Model Tested	GPT-4, GPT-4o, o4-mini, Claude 3.5, Claude 4

---

🔬 Steps to Reproduce

1. Open a .ipynb file in VSCode.
2. Use Copilot Agent to generate or modify code in a cell.
3. After the edit, observe that the cell becomes a blank block.
4. Attempt to interact with the cell → no cursor, no code shown.
5. Reloading VSCode may restore the cell, but subsequent edits break it again.

---

📎 Visual Evidence

Below is a GIF showing the issue.
After using Copilot Agent, the edited cell becomes a blank color block, with no visible content or controls.

---

🧩 Technical Analysis (Hypothesis)

• This appears to be a rendering failure in the Jupyter Notebook editor within VSCode.
• Copilot Agent likely makes edits to the cell that are not properly registered in VSCode’s Notebook API, causing cell UI to break.
• Since both GPT and Claude models cause this, it is likely not model-specific, but rather an issue with how edits are applied to .ipynb cells.

---

🛠️ Possible Cause

• Copilot Agent may not be correctly using the notebook.applyEdit() API or not triggering notebook cell update events.
• The Jupyter extension fails to render the cell post-edit, likely due to missing state update or invalid patch data.

---

➕ Request

Please investigate Copilot Agent’s compatibility with Jupyter Notebook rendering. This is a severe usability issue, preventing Copilot use in .ipynb files.

Let me know if additional logs or diagnostics would help — I can reproduce this consistently.

[DonJayamanne]

Duplicate of #16834