Ctrl+U in Chat input cannot be unbound via keybindings.json (v2.1.112)

Summary

In v2.1.111+, Ctrl+U in the Chat input clears the entire input buffer. This behavior appears to be hardcoded and cannot be disabled via ~/.claude/keybindings.json.

Version

claude --version: 2.1.112 (Claude Code)

Reproduction

1. Create ~/.claude/keybindings.json:

``json
{
"$schema": "https://www.schemastore.org/claude-code-keybindings.json",
"bindings": [
{ "context": "Chat", "bindings": { "ctrl+u": null } }
]
}
``

1. Run /doctor — no keybinding errors reported.
2. Restart Claude Code.
3. Type some text in the chat input and press Ctrl+U.

Expected

Ctrl+U is unbound and does nothing (or at least is user-configurable).

Actual

Ctrl+U still clears the entire input buffer.

Notes

The Chat actions table in https://code.claude.com/docs/en/keybindings does not list Ctrl+U as the default binding for any named action, which suggests the new clear-buffer behavior is hardcoded outside the keybindings system. Exposing it as a named action (e.g. chat:clearAll or similar) would let users unbind or rebind it.