text-input-keybindings

name	text-input-keybindings
description	Use when implementing, reviewing, or designing any text input surface, including TUI composers and editor widgets, REPL or shell prompts, chat input boxes, and single-line form fields. Provides the readline/Emacs keybindings users expect by muscle memory, tiered by how strongly they are expected, plus terminal key-equivalence caveats and conflict guidance for submit/cancel chords.

Text Input Keybindings

Users bring shell and macOS muscle memory to every text box. These bindings come from GNU Readline's Emacs mode; shells, REPLs, and Cocoa text fields all honor them. A text input that ignores them feels broken even when arrow keys work. Implement tier 1 in anything beyond a trivial field, tier 2 in anything called an editor or composer, and treat tier 3 as optional polish.

Tier 1 — table stakes (missing these gets noticed immediately)

Chord	Action
Ctrl+A	move to beginning of line
Ctrl+E	move to end of line
Ctrl+W	delete the word before the cursor (whitespace-delimited)
Ctrl+K	kill from cursor to end of line
Ctrl+U	kill from cursor to beginning of line (whole line in shells)
Backspace / Ctrl+H	delete char before cursor (same byte — see caveats)

Tier 2 — expected in editors, composers, and REPLs

Chord	Action
Ctrl+F / Ctrl+B	forward / back one character (synonyms for arrows)
Ctrl+P / Ctrl+N	previous / next line (synonyms for up/down; multiline only)
Alt+F / Alt+B	forward / back one word
Alt+Backspace	delete word before cursor (letter/digit boundaries, unlike Ctrl+W)
Alt+D	delete word after cursor
Ctrl+D	delete char under cursor (inside an editor; EOF only at an empty shell prompt)
Ctrl+Y	yank back the last text killed by Ctrl+K/Ctrl+U/Ctrl+W/Alt+D

Ctrl+Y requires at least a single-slot kill buffer shared by all kill operations. Implement it together with the kill chords; a Ctrl+K that cannot be undone by Ctrl+Y surprises heavy users.

Tier 3 — power-user extras (nice, rarely missed)

Chord	Action
Ctrl+T	transpose the two characters around the cursor
Alt+T	transpose words
Ctrl+_	undo
Alt+< / Alt+>	beginning / end of buffer

Terminal caveats

• Ctrl+H ≡ Backspace, Ctrl+I ≡ Tab, Ctrl+M ≡ Enter, Ctrl+[ ≡ Esc: the terminal sends the same byte, so these cannot be bound separately and need no separate handling.
• Ctrl+S/Ctrl+Q are XOFF/XON flow control in cooked mode. Raw-mode TUIs receive them fine; line-mode programs may never see them.
• Alt chords arrive as ESC-prefixed sequences; crossterm and similar libraries surface them as an ALT modifier. If the input deliberately ignores Alt-modified characters (a good default against accidental input), carve explicit exceptions for the Alt bindings above.
• Ctrl+Enter is indistinguishable from Enter in many terminals; never make it the only path to an action.

Conflict guidance

• Submit and cancel chords own their keys: a composer using Ctrl+S (submit) and Ctrl+C (cancel) conflicts with nothing above. Do not use Ctrl+D for submit inside an editor; users read it as delete-forward.
• Ctrl+A as select-all is a GUI convention; in terminal inputs it means beginning-of-line. Follow the platform the input lives in.
• When a chord must be dropped for a product reason, prefer dropping from tier 3 upward, and keep synonyms (arrows for Ctrl+F/Ctrl+B) so the capability remains reachable.

Review checklist

1. Tier 1 fully present? Any absence is a finding.
2. Kill chords paired with Ctrl+Y?
3. Ctrl+W vs Alt+Backspace word boundaries distinguished (whitespace vs letter/digit)?
4. Modified keys that are NOT bound do nothing, rather than inserting the raw character or triggering unrelated actions?
5. Multiline inputs: Ctrl+P/Ctrl+N move by visual row through wrapped lines, matching the arrow keys.