[FEATURE] Add redo support: Ctrl+R in vim NORMAL mode and a bindable chat:redo action

Problem Statement

Claude Code's input editor supports undo but has no redo in any form:

• Vim mode implements u (undo) and . (repeat last change) in NORMAL mode, but not Ctrl+R (redo). The docs at code.claude.com/docs/en/interactive-mode confirm no redo command exists.
• The keybinding system has a chat:undo action but no chat:redo counterpart, so redo can't be bound in ~/.claude/keybindings.json either.

One keystroke too many on u and your prompt edit is permanently gone. This is especially painful when composing long prompts, where undo/redo is muscle memory from every other editor.

Proposed Solution

1. Add a chat:redo action to the keybinding system as the counterpart to chat:undo.
2. In vim mode, bind Ctrl+R in NORMAL mode to it, matching vim's standard behavior.

Implementation-wise this is the standard two-stack model: undo pops onto a redo stack, redo pops back, and any new edit clears the redo stack.

Conflict with history search

Ctrl+R currently opens reverse prompt-history search. The clean resolution is to scope by mode: keep Ctrl+R as history search in INSERT mode, and make it redo in NORMAL mode. This mirrors vim itself, where Ctrl+R only means redo in normal mode and has a different meaning in insert mode. Users who want a mode-independent redo can bind chat:redo to another key via keybindings.json.

Prior history

This has been requested repeatedly, but every incarnation was closed by automation rather than an actual decision:

• #29875 (original chat:redo request, went stale)
• #44511 (reopened #29875, closed "not planned" by the inactivity bot)
• #58370 (auto-closed as duplicate of #44511, which was already closed)
• #63820 (auto-closed for inactivity)

Filing fresh since none of these reached a human verdict, and the closed issues are locked so they can no longer collect 👍.

Priority

Medium - Would be very helpful

Feature Category

Interactive mode (TUI)