[Feature Request] Allow Ctrl+B passthrough for readline cursor navigation

Bug Description
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Feature Request: Allow Ctrl+B to pass through to terminal (cursor navigation)

Problem:

Ctrl+B is currently hardcoded in Claude Code for "background task" functionality. However, Ctrl+B is a fundamental readline/Emacs keybinding used by countless developers for moving the cursor backward in terminal environments.

For experienced developers who rely on muscle memory for terminal navigation, having Ctrl+B hijacked is extremely disruptive. This keybinding is deeply ingrained in daily workflows — it's not just a preference, it's years of muscle memory.

Impact:

• Breaks muscle memory built over years of terminal usage
• Forces users to consciously avoid a reflexive keystroke
• Creates friction in an otherwise smooth CLI experience
• Particularly frustrating since Ctrl+F (forward) still works as expected

Suggested Solutions:

1. Allow custom keybindings — Let users remap or disable specific shortcuts
2. Use a less common shortcut — Consider Alt+B or Ctrl+Shift+B for ound tasks instead
3. Provide an option to disable Claude Code shortcuts — A setting like "preserveTerminalKeybindings": true

Many power users choose CLI tools specifically because they respect terminal conventions. Overriding essential navigation keys goes against this expectation.

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Environment Info

• Platform: darwin
• Terminal: cursor
• Version: 2.1.7
• Feedback ID: f6a5ed9e-10c3-456b-bb95-55cd122eb544

Errors

[{"error":"Error: LSP server plugin:typescript-lsp:typescript failed to start: spawn typescript-language-server ENOENT\n    at Object.start (file:///Volumes/Macintosh%20HD%20External%20-%20Data/Users/kongkang/.nvm/versions/node/v22.21.1/lib/node_modules/@anthropic-ai/claude-code/cli.js:2443:22356)\n    at process.processTicksAndRejections (node:internal/process/task_queues:105:5)\n    at async Object.X [as start] (file:///Volumes/Macintosh%20HD%20External%20-%20Data/Users/kongkang/.nvm/versions/node/v22.21.1/lib/node_modules/@anthropic-ai/claude-code/cli.js:2443:24792)","timestamp":"2026-01-14T01:46:28.973Z"},{"error":"Error: spawn typescript-language-server ENOENT\n    at ChildProcess._handle.onexit (node:internal/child_process:285:19)\n    at onErrorNT (node:internal/child_process:483:16)\n    at process.processTicksAndRejections (node:internal/process/task_queues:90:21)","timestamp":"2026-01-14T01:46:28.973Z"},{"error":"Error: Failed to start LSP server plugin:typescript-lsp:typescript: spawn typescript-language-server ENOENT\n    at file:///Volumes/Macintosh%20HD%20External%20-%20Data/Users/kongkang/.nvm/versions/node/v22.21.1/lib/node_modules/@anthropic-ai/claude-code/cli.js:2443:32570\n    at process.processTicksAndRejections (node:internal/process/task_queues:105:5)","timestamp":"2026-01-14T01:46:28.974Z"}]