interactive: speed up mouse scrolling in vscode

internal/agent/modes/interactive.go

@@ -336,9 +336,16 @@ func (i *Interactive) Run(ctx context.Context) error {
 		}
 	}()
 
-	_, _ = term.Write([]byte(tui.SeqBracketedPasteOn))
+	mouseSeqOn := ""
+	mouseSeqOff := ""
+	if isVSCodeTerminal() {
+		mouseSeqOn = tui.SeqMouseOn
+		mouseSeqOff = tui.SeqMouseOff
+	}
+
+	_, _ = term.Write([]byte(tui.SeqBracketedPasteOn + mouseSeqOn))
 	_, _ = term.Write([]byte(tui.SeqAltScreenOn))
-	defer term.Write([]byte(tui.SeqAltScreenOff + tui.SeqBracketedPasteOff + tui.SeqShowCursor))
+	defer term.Write([]byte(tui.SeqAltScreenOff + mouseSeqOff + tui.SeqBracketedPasteOff + tui.SeqShowCursor))
 
 	// Streaming pacer: drains buffered text deltas at a steady rate
 	// so typewriter feel is identical across providers regardless of
@@ -551,6 +558,21 @@ func (i *Interactive) invalidate() {
 	}
 }
 
+func isVSCodeTerminal() bool {
+	return strings.EqualFold(os.Getenv("TERM_PROGRAM"), "vscode")
+}
+
+func mouseWheelScrollRows() int {
+	// VS Code's integrated terminal emits relatively small wheel
+	// steps compared with Ghostty's native scrolling. Mouse-wheel
+	// events get a bigger delta than keyboard arrows so trackpads and
+	// wheel mice feel responsive without changing Up/Down behaviour.
+	if isVSCodeTerminal() {
+		return 12
+	}
+	return 6
+}
+
 // lastCols returns the current terminal width in columns.
 func (i *Interactive) lastCols() int {
 	cols, _ := i.cfg.Terminal.Size()
@@ -1537,6 +1559,14 @@ func (i *Interactive) handleKey(ctx context.Context, k tui.Key) (done bool) {
 	case tui.KeyPageDown:
 		i.scrollBy(-i.chatPage())
 		return false
+	case tui.KeyMouseWheelUp:
+		i.scrollBy(+mouseWheelScrollRows())
+		return false
+	case tui.KeyMouseWheelDown:
+		if i.scrollOffset > 0 {
+			i.scrollBy(-mouseWheelScrollRows())
+		}
+		return false
 	case tui.KeyUp:
 		// Always use up/down for chat scrolling, even when the editor
 		// contains text. This makes keyboard scrolling consistent with

internal/tui/input.go

@@ -42,6 +42,8 @@ const (
 	KeyCtrlW
 	KeyCtrlO
 	KeyPaste
+	KeyMouseWheelUp
+	KeyMouseWheelDown
 	KeyUnknown
 )
 
@@ -222,6 +224,22 @@ func (r *Reader) readCSI() (Key, error) {
 }
 
 func (r *Reader) dispatchCSI(params string, final byte) Key {
+	// SGR mouse mode: CSI < button ; x ; y M/m. Wheel events use
+	// button codes 64 (up) and 65 (down). We ignore coordinates for
+	// now; the chat view only needs scroll direction.
+	if strings.HasPrefix(params, "<") && (final == 'M' || final == 'm') {
+		parts := strings.Split(strings.TrimPrefix(params, "<"), ";")
+		if len(parts) >= 1 {
+			switch parts[0] {
+			case "64":
+				return Key{Kind: KeyMouseWheelUp}
+			case "65":
+				return Key{Kind: KeyMouseWheelDown}
+			}
+		}
+		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

internal/tui/input_test.go

@@ -0,0 +1,28 @@
+package tui
+
+import "testing"
+
+func TestReaderParsesSGRMouseWheel(t *testing.T) {
+	cases := []struct {
+		seq  string
+		want KeyKind
+	}{
+		{"\x1b[<64;10;20M", KeyMouseWheelUp},
+		{"\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)
+		}
+		if k.Kind != tc.want {
+			t.Fatalf("Read(%q) kind=%v, want %v", tc.seq, k.Kind, tc.want)
+		}
+	}
+}

internal/tui/terminal.go

@@ -89,10 +89,16 @@ const (
 	SeqClearLine         = "\x1b[2K"
 	SeqBracketedPasteOn  = "\x1b[?2004h"
 	SeqBracketedPasteOff = "\x1b[?2004l"
-	SeqAltScreenOn       = "\x1b[?1049h"
-	SeqAltScreenOff      = "\x1b[?1049l"
-	SeqSynchronizedOn    = "\x1b[?2026h"
-	SeqSynchronizedOff   = "\x1b[?2026l"
+	// 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
+	// Ghostty, are left alone.
+	SeqMouseOn         = "\x1b[?1000h\x1b[?1006h"
+	SeqMouseOff        = "\x1b[?1000l\x1b[?1006l"
+	SeqAltScreenOn     = "\x1b[?1049h"
+	SeqAltScreenOff    = "\x1b[?1049l"
+	SeqSynchronizedOn  = "\x1b[?2026h"
+	SeqSynchronizedOff = "\x1b[?2026l"
 )
 
 // MoveTo moves the cursor to 1-indexed (row, col).