fix(ui): make Backspace work across all terminals

Ink's key.backspace flag depends on what the terminal sends — Linux
consoles, tmux, and many SSH configs deliver Backspace as raw 0x7f or
0x08 with no flag set, or surface it as key.delete. Catch the raw
bytes too, and route Delete-key presses at end-of-line to backspace
semantics (matches readline). Filter control bytes out of the
printable branch so a stray Backspace can never end up inserted as a
glyph.

Author: halfaipg

src/ui/Input.tsx

@@ -254,12 +254,26 @@ export function Input({ disabled, onSubmit, onAbort, commands, history, cwd }: I
 		if (key.ctrl && input === "a") return setState(moveStart(state));
 		if (key.ctrl && input === "e") return setState(moveEnd(state));
 
-		// Edits
-		if (key.backspace) {
+		// Edits. Some terminals (Linux console, tmux, certain SSH configs)
+		// deliver Backspace as raw 0x7f/0x08 without setting key.backspace,
+		// or even surface it as key.delete. We catch every shape so the
+		// floor — "Backspace deletes a char" — always works.
+		const isBackspaceByte = input === "\x7f" || input === "\b";
+		if (key.backspace || isBackspaceByte) {
 			setSuggestionIdx(0);
 			return setState(backspace(state));
 		}
-		if (key.delete) return setState(deleteForward(state));
+		// `key.delete` historically also fires for Backspace on some Ink
+		// builds, so prefer the backspace semantics when the buffer is
+		// non-empty and the cursor isn't at end-of-line. Forward-delete
+		// stays accessible via Ctrl-D.
+		if (key.delete) {
+			if (state.cursor > 0 && state.cursor === state.buffer.length) {
+				setSuggestionIdx(0);
+				return setState(backspace(state));
+			}
+			return setState(deleteForward(state));
+		}
 		// Ctrl-D matches readline: on an empty buffer it's EOF (i.e. quit),
 		// on a non-empty buffer it deletes forward like Delete.
 		if (key.ctrl && input === "d") {
@@ -279,8 +293,11 @@ export function Input({ disabled, onSubmit, onAbort, commands, history, cwd }: I
 		// Undo
 		if (key.ctrl && input === "z") return setState(undo(state));
 
-		// Printable text — Ink's useInput delivers individual chars (or pasted runs)
-		if (input && !key.ctrl && !key.meta) {
+		// Printable text — Ink's useInput delivers individual chars (or pasted runs).
+		// Strip control bytes (0x00–0x1f, 0x7f) so a stray Backspace or escape
+		// fragment doesn't end up inserted as a glyph in the buffer.
+		const isPrintable = input && !key.ctrl && !key.meta && !/[\x00-\x1f\x7f]/.test(input);
+		if (isPrintable) {
 			setSuggestionIdx(0);
 			// Once the user starts editing on top of a recalled history
 			// entry, snap out of history mode — the entry is now their