wip

internal/vt/emulator.go

@@ -57,6 +57,15 @@ type Emulator interface {
 	// ActiveScreen reports whether we are on the primary or alternate buffer.
 	ActiveScreen() (Screen, error)
 
+	// ScrollViewportTop moves the viewport to the top of the scrollback.
+	ScrollViewportTop() error
+
+	// ScrollViewportBottom moves the viewport back to the active area.
+	ScrollViewportBottom() error
+
+	// ScrollViewportDelta moves the viewport by `delta` rows (negative = up).
+	ScrollViewportDelta(delta int) error
+
 	// OnWritePTY registers a callback that fires when the emulator wants
 	// to write bytes back to the PTY master (e.g. responses to DA / DSR
 	// queries). The callback runs synchronously inside Write and must not

internal/vt/ghostty.go

@@ -81,6 +81,27 @@ static GhosttyResult patterm_set_userdata(GhosttyTerminal t, uintptr_t ud) {
                                 (const void *)ud);
 }
 
+static void patterm_scroll_viewport_top(GhosttyTerminal t) {
+    GhosttyTerminalScrollViewport beh;
+    beh.tag = GHOSTTY_SCROLL_VIEWPORT_TOP;
+    beh.value.delta = 0;
+    ghostty_terminal_scroll_viewport(t, beh);
+}
+
+static void patterm_scroll_viewport_bottom(GhosttyTerminal t) {
+    GhosttyTerminalScrollViewport beh;
+    beh.tag = GHOSTTY_SCROLL_VIEWPORT_BOTTOM;
+    beh.value.delta = 0;
+    ghostty_terminal_scroll_viewport(t, beh);
+}
+
+static void patterm_scroll_viewport_delta(GhosttyTerminal t, intptr_t d) {
+    GhosttyTerminalScrollViewport beh;
+    beh.tag = GHOSTTY_SCROLL_VIEWPORT_DELTA;
+    beh.value.delta = d;
+    ghostty_terminal_scroll_viewport(t, beh);
+}
+
 static GhosttyFormatterTerminalOptions patterm_plain_fmt_opts(void) {
     GhosttyFormatterTerminalOptions opts = GHOSTTY_INIT_SIZED(GhosttyFormatterTerminalOptions);
     opts.emit = GHOSTTY_FORMATTER_FORMAT_PLAIN;
@@ -161,7 +182,7 @@ func NewGhosttyEmulator(cols, rows uint16) (*GhosttyEmulator, error) {
 	opts := C.GhosttyTerminalOptions{
 		cols:           C.uint16_t(cols),
 		rows:           C.uint16_t(rows),
-		max_scrollback: 0,
+		max_scrollback: 5000,
 	}
 
 	if rc := C.ghostty_terminal_new(nil, &e.term, opts); rc != C.GHOSTTY_SUCCESS {
@@ -539,6 +560,39 @@ func (e *GhosttyEmulator) ActiveScreen() (Screen, error) {
 	return ScreenPrimary, nil
 }
 
+// ScrollViewportTop scrolls the viewport to the top of the scrollback.
+func (e *GhosttyEmulator) ScrollViewportTop() error {
+	e.mu.Lock()
+	defer e.mu.Unlock()
+	if e.closed {
+		return errors.New("vt: emulator closed")
+	}
+	C.patterm_scroll_viewport_top(e.term)
+	return nil
+}
+
+// ScrollViewportBottom scrolls the viewport to the bottom (active area).
+func (e *GhosttyEmulator) ScrollViewportBottom() error {
+	e.mu.Lock()
+	defer e.mu.Unlock()
+	if e.closed {
+		return errors.New("vt: emulator closed")
+	}
+	C.patterm_scroll_viewport_bottom(e.term)
+	return nil
+}
+
+// ScrollViewportDelta scrolls the viewport by `delta` rows. Negative is up.
+func (e *GhosttyEmulator) ScrollViewportDelta(delta int) error {
+	e.mu.Lock()
+	defer e.mu.Unlock()
+	if e.closed {
+		return errors.New("vt: emulator closed")
+	}
+	C.patterm_scroll_viewport_delta(e.term, C.intptr_t(delta))
+	return nil
+}
+
 func (e *GhosttyEmulator) OnWritePTY(fn func([]byte)) {
 	if fn == nil {
 		e.onWrite.Store(nil)

internal/vt/ghostty_nocgo.go

@@ -24,6 +24,9 @@ func (e *GhosttyEmulator) SerializeVT() ([]byte, error)    { return nil, errStub
 func (e *GhosttyEmulator) StyledScreenVT() ([]byte, error) { return nil, errStub }
 func (e *GhosttyEmulator) Cursor() (CursorState, error)    { return CursorState{}, errStub }
 func (e *GhosttyEmulator) ActiveScreen() (Screen, error)   { return 0, errStub }
+func (e *GhosttyEmulator) ScrollViewportTop() error        { return errStub }
+func (e *GhosttyEmulator) ScrollViewportBottom() error     { return errStub }
+func (e *GhosttyEmulator) ScrollViewportDelta(int) error   { return errStub }
 func (e *GhosttyEmulator) OnWritePTY(fn func([]byte))      {}
 func (e *GhosttyEmulator) Close() error                    { return nil }