OAuth sign-in wait screen has no cancel: Esc, Ctrl-C ×2, q, Ctrl-D, Ctrl-Z all leave it unchanged; Enter loops through the error screen

**Environment:** Claude Code v2.1.219, Linux, running under tmux in a 40×29 pty (a phone-sized terminal), fresh `CLAUDE_CONFIG_DIR`.

## What happens

During `/login` → OAuth, once the flow reaches the wait screen —

```
Browser didn't open? Use the (c to
url below to sign in copy)

https://claude.com/cai/oauth/authorize?…

Paste code here if prompted >
```

— **no keystroke leaves it.** Measured one key at a time against the live process (screen captured after each input; the pane command instrumented so an exit could not be missed):

| input on the wait screen | result |
|---|---|
| Escape | screen unchanged |
| Ctrl-C ×1 | unchanged |
| Ctrl-C ×2 (Claude Code's own "press again to exit" convention) | unchanged |
| `q` | types into the code field |
| Ctrl-D | unchanged |
| Ctrl-Z | unchanged |
| Enter (empty code) | → "OAuth error: Invalid code … Press Enter to retry." |
| Enter again (retry) | → back to the same wait screen — a closed loop |
| Escape after the retry | unchanged |

`[claude exited]` never printed. The wait screen and its error sibling form a closed loop whose only exits are completing the login or killing the process.

## Why it matters

The login **picker** honors `Esc to cancel`, so a user who chose the wrong login method (or whose browser handoff failed — common when Claude Code runs on a remote host and the browser cannot open) reasonably expects Escape to work one screen later. It doesn't, and nothing on the screen says so. On a remote/mobile terminal this is a dead end: you either finish a sign-in you may not want, or kill the process.

## Ask

Escape (or Ctrl-C) on the OAuth wait screen should cancel back to the login method picker — matching the escape hatch the picker itself already advertises. Failing that, the screen should say what actually exits it.

Start at the /login OAuth flow, comparing the login method picker with the OAuth wait and error screens described in the issue. Trace how Escape and Ctrl-C are handled on each screen, then verify that cancellation returns to the picker and that retry behavior still works without trapping the user in the wait-screen loop.

索引モデルが issue の本文から書いたものです。