[Bug] Ctrl-based keyboard shortcuts unresponsive in agent view after extended use

**Bug Description**
Title: All Ctrl-based keyboard shortcuts (including Ctrl+C) stop working in agent view after extended use

Description
While using Claude Code in agent view, all Ctrl-based keyboard shortcuts stop responding after the session has been running for a while. This includes basic ones like Ctrl+C, not just Claude Code-specific shortcuts. Other input (regular typing, slash commands) still works. Exiting with /quit and restarting Claude Code restores the shortcuts, but the issue eventually comes back.

Steps to reproduce

Start Claude Code in the VS Code integrated terminal and open agent view.
Use it normally for a while (the exact duration varies).
Press any Ctrl shortcut (e.g. Ctrl+C).

Expected behavior
Ctrl shortcuts, including Ctrl+C, keep working for the entire session.

Actual behavior
After some time, no Ctrl shortcut has any effect, including Ctrl+C. Running /quit and relaunching Claude Code fixes it temporarily.

Environment

Claude Code version: 2.1.274
OS: macOS 26.7
Terminal: VS Code integrated terminal (VS Code 1.138.0)
Shell: zsh

Additional notes
I haven't found a specific action that triggers it; it seems to happen after a period of use rather than immediately. Since Ctrl+C also stops working and restarting Claude Code (without restarting VS Code) fixes it, the issue seems to be on the Claude Code side rather than VS Code capturing the keys. Happy to provide logs or test a debug build if helpful.

**Environment Info**
- Platform: darwin
- Terminal: vscode
- Version: 2.1.274
- Feedback ID: b36cb0b1-5033-4502-b4b5-44e65e3b1e30

**Errors**
```json
[]
```

Start by reproducing the issue in agent view from a VS Code integrated terminal on macOS with zsh, exercising Ctrl+C and other Ctrl shortcuts after extended use. Compare input before and after the failure and use feedback ID b36cb0b1-5033-4502-b4b5-44e65e3b1e30 for investigation. Done means all Ctrl shortcuts remain responsive throughout the session without requiring /quit.

Written by the indexing model from the issue text.