Ctrl+C once does not interrupt ongoing operation

Environment:

• OS: macOS (Darwin 25.3.0)
• Terminal: iTerm2 + macOS Terminal
• Claude Code version: latest

Steps to reproduce:

1. Start Claude Code
2. Run a command that triggers a long-running operation or tool use
3. Press Ctrl+C once while operation is in progress

Expected behavior:
Operation stops, Claude Code remains open and waits for next input

Actual behavior:
Ctrl+C once does NOT stop the operation.
Only Ctrl+C twice works, but that exits Claude Code completely.

Additional context:
ESC x2 also stops the operation but sometimes leaves the terminal in a frozen state (cannot type anything after). This is reproducible on both iTerm2 and macOS Terminal.