[bug] Copilot CLI input no longer reaches TUI after switching away and back to its terminal pane #4542

Describe the bug

When the GitHub Copilot CLI (copilot) is running in a Superset terminal pane, switching away from that pane and then returning leaves the TUI in a state where keyboard input no longer lands in Copilot's input field. The cursor visibly leaves the input area on return. The session itself is not frozen, Ctrl+C still works and lets me restart the session so the pane isn't blocked, but I can't continue the existing Copilot conversation, only kill it.

This looks like the same family as #3309 (Codex pane reattach corrupts state), #2968 (Droid TUI freeze after switch), and #3321 (terminal repaint into stale visual state after focus/workspace restore), but for a different TUI (Copilot CLI), with a distinct symptom: input is silently dropped and focus is lost on the TUI input field.

Expected behavior

After switching away and back to a Copilot CLI pane, the TUI should still receive keyboard input and focus should remain on its input field, same as Claude Code.

Actual behavior

After returning to the pane:

• Keystrokes don't appear in Copilot's input field, nothing happens visually.
• The cursor is no longer in/on Copilot's input field.
• Ctrl+C still works (so the shell/TUI isn't truly frozen), but only as a kill switch. The only path forward is to terminate the Copilot session and start a new one.

Reproduction

1. Open a new Superset terminal pane.
2. Run copilot.
3. Type something, works as expected.
4. Switch to a different tab/workspace (or otherwise change focus away from the Copilot pane).
5. Switch back to the Copilot pane.
6. Try to type, nothing lands in Copilot's input field.

Control case

The same workflow with Claude Code in a Superset pane does not exhibit this on my machine.

Environment

• Superset Desktop: 1.9.1
• macOS: 26.4.1 (build 25E253)
• Hardware: Apple Silicon (arm64)
• GitHub Copilot CLI: 1.0.47