[FEATURE] Spell check (red underline) in the terminal prompt input

Preflight Checklist

• [x] I have searched existing requests and this feature hasn't been requested yet for the terminal (related: #69668, #81814)
• [x] This is a single feature request (not multiple features)

Problem Statement

Claude Desktop underlines misspelled words as you type, but the Claude Code terminal prompt doesn't. In long sessions I type fast and send prompts with typos I'd have caught if they were underlined. Typos can change what I'm asking for, and fixing them afterward costs a turn.

Proposed Solution

Underline misspelled words in the prompt input with a red squiggle, or a plain underline on terminals without curly underline support, the way Claude Desktop already does.

Nice to have:

• A keybinding to cycle through suggestions for the word under the cursor
• A spellcheck setting to turn it on or off, plus a language option
• Skip code spans, file paths, @-mentions and slash commands

Related

• #69668 (general spelling/grammar request for chat input)
• #81814 (VS Code extension chat input)
• Claude Desktop already has this

Environment

Windows 11, Claude Code 2.1.282, VS Code integrated terminal