Support Shift-Enter in terminal input

packages/agent/modes/help.go

@@ -11,7 +11,7 @@ import (
 // helpKeyRows is the list of keybindings shown by /help.
 var helpKeyRows = [][2]string{
 	{"enter", "submit the current input"},
-	{"alt+enter", "insert a newline"},
+	{"shift+enter / alt+enter", "insert a newline"},
 	{"tab", "complete the highlighted slash command"},
 	{"esc", "cancel the current turn (while busy) - clear the input (while idle)"},
 	{"ctrl+c", "exit (while idle) - cancel the current turn (while busy)"},

packages/agent/modes/interactive.go

@@ -532,8 +532,8 @@ func (i *Interactive) Run(ctx context.Context) error {
 	// enter the alternate-screen buffer (CSI ?1049h). The renderer emits
 	// chat as normal terminal flow/scrollback and redraws only the live
 	// input/status block on normal typing.
-	_, _ = term.Write([]byte(tui.SeqBracketedPasteOn + tui.SeqResetScrollRegion + tui.SeqDeleteKittyImages + tui.SeqClearScreenNoHome + tui.SeqClearScrollback + tui.MoveTo(1, 1)))
-	defer term.Write([]byte(tui.SeqResetScrollRegion + tui.SeqDeleteKittyImages + tui.SeqBracketedPasteOff + tui.SeqShowCursor))
+	_, _ = term.Write([]byte(tui.SeqBracketedPasteOn + tui.SeqEnhancedKeyboardOn + tui.SeqResetScrollRegion + tui.SeqDeleteKittyImages + tui.SeqClearScreenNoHome + tui.SeqClearScrollback + tui.MoveTo(1, 1)))
+	defer term.Write([]byte(tui.SeqResetScrollRegion + tui.SeqDeleteKittyImages + tui.SeqEnhancedKeyboardOff + tui.SeqBracketedPasteOff + tui.SeqShowCursor))
 
 	// Streaming pacer: drains buffered text deltas at a steady rate
 	// so typewriter feel is identical across providers regardless of
@@ -2040,8 +2040,8 @@ func (i *Interactive) handleKey(ctx context.Context, k tui.Key) (done bool) {
 	// messages are queued and delivered as follow-up turns when the
 	// current turn ends. See the submit handler below.
 
-	if k.Kind == tui.KeyEnter && k.Alt {
-		i.ed.HandleKey(tui.Key{Kind: tui.KeyRune, Rune: '\n', Alt: true})
+	if k.Kind == tui.KeyEnter && (k.Alt || k.Shift) {
+		i.ed.HandleKey(k)
 		return false
 	}
 

packages/tui/editor.go

@@ -127,9 +127,10 @@ func (e *Editor) HandleKey(k Key) (submit bool) {
 		}
 		e.insert(string(k.Rune))
 	case KeyEnter:
-		// Shift+Enter would be a separate key in some terminals; we treat
-		// the literal newline byte as Enter. Newline on submit is a decision
-		// for the outer UI via slash commands. Here Enter submits.
+		if k.Shift || k.Alt {
+			e.newline()
+			return false
+		}
 		return true
 	case KeyBackspace:
 		if k.Alt {

packages/tui/editor_shift_enter_test.go

@@ -0,0 +1,24 @@
+package tui
+
+import "testing"
+
+func TestEditorShiftEnterInsertsNewline(t *testing.T) {
+	e := NewEditor("> ")
+	e.HandleKey(Key{Kind: KeyRune, Rune: 'a'})
+	if submit := e.HandleKey(Key{Kind: KeyEnter, Shift: true}); submit {
+		t.Fatal("Shift+Enter submitted; want newline")
+	}
+	e.HandleKey(Key{Kind: KeyRune, Rune: 'b'})
+
+	if got, want := e.Value(), "a\nb"; got != want {
+		t.Fatalf("Value() = %q, want %q", got, want)
+	}
+}
+
+func TestEditorPlainEnterSubmits(t *testing.T) {
+	e := NewEditor("> ")
+	e.HandleKey(Key{Kind: KeyRune, Rune: 'a'})
+	if submit := e.HandleKey(Key{Kind: KeyEnter}); !submit {
+		t.Fatal("Enter did not submit")
+	}
+}

packages/tui/input.go

@@ -1,6 +1,7 @@
 package tui
 
 import (
+	"strconv"
 	"strings"
 	"time"
 )
@@ -12,6 +13,7 @@ type Key struct {
 	Paste string // for KeyPaste
 	Ctrl  bool
 	Alt   bool
+	Shift bool
 }
 
 type KeyKind int
@@ -240,27 +242,26 @@ func (r *Reader) dispatchCSI(params string, final byte) Key {
 		return Key{Kind: KeyUnknown}
 	}
 
-	// Modified arrow keys come in as CSI 1;<mod><final>. Modifier values
-	// we care about: 2=Shift, 3=Alt/Option, 5=Ctrl. We only extract Alt.
-	var alt bool
-	if params != "" {
-		if i := strings.IndexByte(params, ';'); i >= 0 {
-			mod := params[i+1:]
-			if mod == "3" || mod == "4" || mod == "7" || mod == "8" {
-				// 3=Alt, 4=Shift+Alt, 7=Ctrl+Alt, 8=Ctrl+Shift+Alt
-				alt = true
-			}
+	shift, alt := parseCSIModifiers(params)
+	if final == 'u' {
+		if key, ok := parseCSIU(params); ok {
+			return key
+		}
+	}
+	if final == '~' {
+		if key, ok := parseModifyOtherKeys(params); ok {
+			return key
 		}
 	}
 	switch final {
 	case 'A':
-		return Key{Kind: KeyUp, Alt: alt}
+		return Key{Kind: KeyUp, Alt: alt, Shift: shift}
 	case 'B':
-		return Key{Kind: KeyDown, Alt: alt}
+		return Key{Kind: KeyDown, Alt: alt, Shift: shift}
 	case 'C':
-		return Key{Kind: KeyRight, Alt: alt}
+		return Key{Kind: KeyRight, Alt: alt, Shift: shift}
 	case 'D':
-		return Key{Kind: KeyLeft, Alt: alt}
+		return Key{Kind: KeyLeft, Alt: alt, Shift: shift}
 	case 'H':
 		return Key{Kind: KeyHome}
 	case 'F':
@@ -283,6 +284,93 @@ func (r *Reader) dispatchCSI(params string, final byte) Key {
 	return Key{Kind: KeyUnknown}
 }
 
+func parseCSIModifiers(params string) (shift, alt bool) {
+	if params == "" {
+		return false, false
+	}
+	i := strings.LastIndexByte(params, ';')
+	if i < 0 || i+1 >= len(params) {
+		return false, false
+	}
+	mod, err := strconv.Atoi(params[i+1:])
+	if err != nil {
+		return false, false
+	}
+	// Xterm-style modifier values are 1 plus a bitmask:
+	// 2=Shift, 3=Alt, 4=Shift+Alt, 5=Ctrl, 6=Shift+Ctrl,
+	// 7=Alt+Ctrl, 8=Shift+Alt+Ctrl.
+	bits := mod - 1
+	return bits&1 != 0, bits&2 != 0
+}
+
+func parseCSIU(params string) (Key, bool) {
+	parts := strings.Split(params, ";")
+	if len(parts) == 0 {
+		return Key{}, false
+	}
+	code, err := strconv.Atoi(parts[0])
+	if err != nil {
+		return Key{}, false
+	}
+	mod := 1
+	if len(parts) >= 2 {
+		if mod, err = strconv.Atoi(parts[1]); err != nil {
+			return Key{}, false
+		}
+	}
+	return keyFromModifiedCode(code, mod)
+}
+
+func parseModifyOtherKeys(params string) (Key, bool) {
+	parts := strings.Split(params, ";")
+	if len(parts) != 3 || parts[0] != "27" {
+		return Key{}, false
+	}
+	mod, err := strconv.Atoi(parts[1])
+	if err != nil {
+		return Key{}, false
+	}
+	code, err := strconv.Atoi(parts[2])
+	if err != nil {
+		return Key{}, false
+	}
+	return keyFromModifiedCode(code, mod)
+}
+
+func keyFromModifiedCode(code, mod int) (Key, bool) {
+	bits := mod - 1
+	shift := bits&1 != 0
+	alt := bits&2 != 0
+	ctrl := bits&4 != 0
+	switch code {
+	case 13:
+		return Key{Kind: KeyEnter, Shift: shift, Alt: alt, Ctrl: ctrl}, true
+	}
+	if ctrl {
+		switch code {
+		case 'c', 'C':
+			return Key{Kind: KeyCtrlC, Shift: shift, Alt: alt, Ctrl: true}, true
+		case 'd', 'D':
+			return Key{Kind: KeyCtrlD, Shift: shift, Alt: alt, Ctrl: true}, true
+		case 'l', 'L':
+			return Key{Kind: KeyCtrlL, Shift: shift, Alt: alt, Ctrl: true}, true
+		case 'u', 'U':
+			return Key{Kind: KeyCtrlU, Shift: shift, Alt: alt, Ctrl: true}, true
+		case 'k', 'K':
+			return Key{Kind: KeyCtrlK, Shift: shift, Alt: alt, Ctrl: true}, true
+		case 'a', 'A':
+			return Key{Kind: KeyCtrlA, Shift: shift, Alt: alt, Ctrl: true}, true
+		case 'e', 'E':
+			return Key{Kind: KeyCtrlE, Shift: shift, Alt: alt, Ctrl: true}, true
+		case 'w', 'W':
+			return Key{Kind: KeyCtrlW, Shift: shift, Alt: alt, Ctrl: true}, true
+		case 'o', 'O':
+			return Key{Kind: KeyCtrlO, Shift: shift, Alt: alt, Ctrl: true}, true
+		}
+	}
+	return Key{}, false
+}
+
 // readPaste reads until ESC [ 2 0 1 ~ and returns the pasted text.
 func (r *Reader) readPaste() Key {
 	var sb strings.Builder

packages/tui/input_test.go

@@ -2,6 +2,34 @@ package tui
 
 import "testing"
 
+func TestReaderParsesCSIUShiftEnter(t *testing.T) {
+	k := readKey(t, "\x1b[13;2u")
+	if k.Kind != KeyEnter || !k.Shift || k.Alt {
+		t.Fatalf("Read kind=%v shift=%v alt=%v, want shift+enter", k.Kind, k.Shift, k.Alt)
+	}
+}
+
+func TestReaderParsesModifyOtherKeysShiftEnter(t *testing.T) {
+	k := readKey(t, "\x1b[27;2;13~")
+	if k.Kind != KeyEnter || !k.Shift || k.Alt {
+		t.Fatalf("Read kind=%v shift=%v alt=%v, want shift+enter", k.Kind, k.Shift, k.Alt)
+	}
+}
+
+func TestReaderParsesCSIUCtrlC(t *testing.T) {
+	k := readKey(t, "\x1b[99;5u")
+	if k.Kind != KeyCtrlC || !k.Ctrl {
+		t.Fatalf("Read kind=%v ctrl=%v, want ctrl+c", k.Kind, k.Ctrl)
+	}
+}
+
+func TestReaderParsesModifyOtherKeysCtrlC(t *testing.T) {
+	k := readKey(t, "\x1b[27;5;99~")
+	if k.Kind != KeyCtrlC || !k.Ctrl {
+		t.Fatalf("Read kind=%v ctrl=%v, want ctrl+c", k.Kind, k.Ctrl)
+	}
+}
+
 func TestReaderParsesSGRMouseWheel(t *testing.T) {
 	cases := []struct {
 		seq  string
@@ -11,18 +39,24 @@ func TestReaderParsesSGRMouseWheel(t *testing.T) {
 		{"\x1b[<65;10;20M", KeyMouseWheelDown},
 	}
 	for _, tc := range cases {
-		idx := 0
-		r := NewReader(func() (byte, error) {
-			b := tc.seq[idx]
-			idx++
-			return b, nil
-		})
-		k, err := r.Read()
-		if err != nil {
-			t.Fatalf("Read(%q): %v", tc.seq, err)
-		}
+		k := readKey(t, tc.seq)
 		if k.Kind != tc.want {
 			t.Fatalf("Read(%q) kind=%v, want %v", tc.seq, k.Kind, tc.want)
 		}
 	}
 }
+
+func readKey(t *testing.T, seq string) Key {
+	t.Helper()
+	idx := 0
+	r := NewReader(func() (byte, error) {
+		b := seq[idx]
+		idx++
+		return b, nil
+	})
+	k, err := r.Read()
+	if err != nil {
+		t.Fatalf("Read(%q): %v", seq, err)
+	}
+	return k
+}

packages/tui/terminal.go

@@ -107,6 +107,13 @@ const (
 	SeqDeleteKittyImages = "\x1b_Ga=d\x1b\\"
 	SeqBracketedPasteOn  = "\x1b[?2004h"
 	SeqBracketedPasteOff = "\x1b[?2004l"
+	// Request enhanced keyboard reporting where supported. Kitty-style
+	// keyboard protocol covers Ghostty, Kitty, VS Code's integrated
+	// terminal, and recent xterm.js builds. Xterm modifyOtherKeys is a
+	// useful fallback for terminals/tmux configurations that expose
+	// modified Enter as CSI 27;<mod>;<code>~.
+	SeqEnhancedKeyboardOn  = "\x1b[>1u\x1b[>4;2m"
+	SeqEnhancedKeyboardOff = "\x1b[<u\x1b[>4m"
 	// Basic mouse tracking + SGR extended coordinates. Used only
 	// when explicitly enabled by the interactive mode (currently VS
 	// Code terminal) so terminals with good native scrolling, like