Keep scrollback under a full-screen scroll region

Architecture.md

@@ -75,10 +75,9 @@ Generated at runtime, not in the repo: `Packages/User/vterm/vterm.hidden-color-s
 | `vterm_cleanup` | `VtermCleanupCommand` | renderer, on process exit |
 | `vterm_close` | `VtermCloseCommand` | nothing — available for a user keybinding |
 | `vterm_clear_undo_stack` / `vterm_noop` | `commands.py` | internal |
-| `vterm_scroll` / `vterm_mouse_click` | `mouse.py` | mousemap, `drag_select` interception |
+| `vterm_scroll` / `vterm_mouse_press` / `vterm_mouse_release` | `mouse.py` | mousemap |
 
-Two application-wide `EventListener`s: `VtermCoreEventListener` (`listeners.py`) and
-`VtermMouseEventListener` (`mouse.py`).
+One application-wide `EventListener`: `VtermCoreEventListener` (`listeners.py`).
 
 
 ---

Default (OSX).sublime-mousemap

@@ -11,6 +11,13 @@
         "args": {"up": false},
         "context": [{"key": "vterm_view.wheel_captured", "operand": true}]
     },
+    {
+        // press reports the click, release reports the drag
+        "button": "button1",
+        "press_command": "vterm_mouse_press",
+        "command": "vterm_mouse_release",
+        "context": [{"key": "vterm_view.mouse_reporting", "operand": true}]
+    },
     {
         // press_command: sublime's own button3 binding is a column drag_select,
         // which would clear the selection before a release command could read it

README.md

@@ -79,10 +79,11 @@ or turns it off. Copy/paste use the normal Sublime keys, and pastes are
 bracketed when the app asks for it. Copying re-joins soft-wrapped lines. The
 middle button pastes the current selection straight into the app, X11-style,
 without going near the clipboard; it does nothing when nothing is selected. The
-wheel scrolls the view normally; while the app tracks the mouse the wheel and
-left click go to it instead, and on the alternate screen without tracking each
-wheel tick sends arrow keys (alternate scroll, as kitty/iTerm2 do — this is
-what scrolls Claude Code's fullscreen UI before it enables mouse reporting).
+wheel scrolls the view normally; while the app tracks the mouse the wheel, clicks
+and drags go to it instead (Claude Code's own mouse selection and copy work as in
+kitty), and on the alternate screen without tracking each wheel tick sends arrow
+keys (alternate scroll, as kitty/iTerm2 do — this is what scrolls Claude Code's
+fullscreen UI before it enables mouse reporting).
 Sublime raises no wheel event at all for the trackpad (sublime_text#1838): set
 a utility such as [LinearMouse](https://linearmouse.app/) to discrete scrolling
 for Sublime Text and it arrives as wheel notches like any other. A notch sends the
@@ -149,15 +150,16 @@ terminal protocols — see `Architecture.md`.
   into the view: an app that does not echo (vim in normal mode) would otherwise
   leave the character behind. `on_modified` in `vterm/listeners.py` remains the
   fallback for IME and composed input.
-- `vterm/mouse.py` — SGR mouse reporting (wheel, click) when the app enables
+- `vterm/mouse.py` — SGR mouse reporting (wheel, click, drag) when the app enables
   tracking; native selection and scrolling otherwise. The trackpad is not
   handled: it reaches no mousemap on macOS and is converted to wheel notches
   outside the plugin.
 
 Supported: alt screen (1049), synchronized output (2026), bracketed paste (2004),
-mouse tracking 1000/1002/1003 + SGR 1006 (wheel and left click are reported; no
-drag, no right button; the middle button pastes the selection instead of being
-reported), focus events (1004),
+mouse tracking 1000/1002/1003 + SGR 1006 (wheel and left button are reported; a
+drag arrives as one motion at release, since Sublime raises none; no right
+button; the middle button pastes the selection instead of being reported),
+focus events (1004),
 xterm modifyOtherKeys (`CSI > 4 ; n m`, for the modified keys with no
 unambiguous legacy encoding: enter, tab, backspace, space), cursor styles (DECSCUSR —
 block/bar and blink/steady via the view's caret settings; underline falls back

main.py

@@ -26,8 +26,8 @@ from .vterm.commands import (
 )
 from .vterm.listeners import VtermCoreEventListener
 from .vterm.mouse import (
-    VtermMouseClickCommand,
-    VtermMouseEventListener,
+    VtermMousePressCommand,
+    VtermMouseReleaseCommand,
     VtermScrollCommand,
 )
 from .vterm.scheme import build_startup_schemes

tests/test_emulator.py

@@ -141,6 +141,11 @@ def run_case(char_by_char):
     assert len(screen.history) == 1, (tag, len(screen.history))
     assert screen.history[0][0].data == "a", tag
 
+    # an explicit full-screen scroll region still feeds scrollback
+    proc, screen, stream = make(10, 3)
+    feed(stream, "\x1b[1;3ra\r\nb\r\nc\r\nd", char_by_char)
+    assert len(screen.history) == 1, (tag, len(screen.history))
+
     # ED 3 clears history and fires callback
     cleared = []
     proc = FakeProcess()

tests/test_render.py

@@ -9,7 +9,7 @@ from _bootstrap import FakeProcess
 import sublime
 from vterm.commands import VtermKeypressCommand
 from vterm.emulator import VtScreen, VtStream
-from vterm.mouse import VtermMouseClickCommand, VtermScrollCommand
+from vterm.mouse import VtermMousePressCommand, VtermMouseReleaseCommand, VtermScrollCommand
 from vterm.render import (
     CHUNK,
     RenderState,
@@ -626,19 +626,31 @@ terminal.view.window_to_text = lambda xy: 0
 window = FakeWindow(active=object())
 terminal.view.window = lambda: window
 stream.feed("\x1b[?1002h\x1b[?1006h")
-click = VtermMouseClickCommand.__new__(VtermMouseClickCommand)
-click.view = terminal.view
+mouse_press = VtermMousePressCommand.__new__(VtermMousePressCommand)
+mouse_press.view = terminal.view
+mouse_release = VtermMouseReleaseCommand.__new__(VtermMouseReleaseCommand)
+mouse_release.view = terminal.view
 event = {"x": 0, "y": 0, "button": 1}
 
-click.run(None, event)
+mouse_press.run(None, event)
 assert window.active_view() is terminal.view, "click did not focus the tab"
+mouse_release.run(None, event)
 assert terminal.process.written == "", repr(terminal.process.written)
 
-# once focused, the same click reports as before
-click.run(None, event)
+# once focused, press and release at one cell report a click
+mouse_press.run(None, event)
+mouse_release.run(None, event)
 assert terminal.process.written == "\x1b[<0;1;1M\x1b[<0;1;1m", repr(terminal.process.written)
 
-print("click focus tests passed (first click focuses only, then reports)")
+# a release elsewhere reports one drag motion first
+terminal.process.writes.clear()
+terminal.view.text = "r0    \nr1    \nr2    \nr3    \nr4    \n"
+mouse_press.run(None, event)
+terminal.view.window_to_text = lambda xy: terminal.view.text_point(2, 4)
+mouse_release.run(None, event)
+assert terminal.process.written == "\x1b[<0;1;1M\x1b[<32;5;3M\x1b[<0;5;3m", repr(terminal.process.written)
+
+print("click tests passed (first click focuses only; press, drag and release report)")
 
 
 # entering the alt screen folds the scrollback away (kitty hides it); leaving

vterm/emulator.py

@@ -442,7 +442,9 @@ class VtScreen(pyte.Screen):
 
     def index(self):
         """Line feed; at the bottom of the primary screen the top row goes to scrollback."""
-        if not self.alternate_buffer_mode and self.cursor.y == self.lines - 1 and self.margins is None:
+        # a region spanning the whole screen (CSI 1;<lines> r) is no region
+        full = self.margins is None or self.margins == (0, self.lines - 1)
+        if not self.alternate_buffer_mode and self.cursor.y == self.lines - 1 and full:
             self.push_lines_into_history(1)
         super().index()
 

vterm/listeners.py

@@ -88,7 +88,7 @@ class VtermCoreEventListener(sublime_plugin.EventListener):
         """Answer the contexts the mousemap needs"""
         # keymap contexts are native "setting.x"; mousemaps do not evaluate
         # those the same way, so their flags still need the hook
-        if key not in ("vterm_view", "vterm_view.wheel_captured"):
+        if key not in ("vterm_view", "vterm_view.wheel_captured", "vterm_view.mouse_reporting"):
             return None
         value = view.settings().get(key, False)
         if operator == sublime.OP_EQUAL:

vterm/mouse.py

@@ -13,6 +13,8 @@ from .utils import settings
 # SGR button numbers for the wheel; 64 is the "scroll" bit plus direction
 WHEEL_UP = 64
 WHEEL_DOWN = 65
+# button 0 with the "moved while held" bit
+MOTION = 32
 
 
 def send_scroll(terminal, up, lines, cell=None):
@@ -36,7 +38,7 @@ def _event_to_cell(view, terminal, event, clamp=False):
     """Map a mouse event to 1-based (col, row) on the live screen, or None.
 
     Clamping pulls a point above or below the screen onto the nearest row: the
-    wheel still belongs to the app there, a click does not."""
+    wheel and a release still belong to the app there, a press does not."""
     pt = view.window_to_text((event["x"], event["y"]))
     row, col = view.rowcol(pt)
     row -= terminal.offset
@@ -48,46 +50,60 @@ def _event_to_cell(view, terminal, event, clamp=False):
     return (min(col, screen.columns - 1) + 1, row + 1)
 
 
-class VtermMouseEventListener(sublime_plugin.EventListener):
-    """Hands button-1 clicks to the app, but only while it tracks the mouse."""
-
-    def on_text_command(self, view, name, args):
-        """Replace drag_select with a mouse report; other click variants stay native."""
-        terminal = Terminal.from_id(view.id())
-        if not terminal:
-            return
-        if not terminal.screen.mouse_reporting_enabled():
-            # leave selection, caret and scrolling to sublime
-            return
-        if name == "drag_select" and args and args.get("event", {}).get("button") == 1 and len(args) == 1:
-            return ("vterm_mouse_click", {"event": args["event"]})
-
-
-class VtermMouseClickCommand(sublime_plugin.TextCommand):
-    """Reports a click to the app, or focuses the tab if it was not active."""
+class VtermMousePressCommand(sublime_plugin.TextCommand):
+    """Bound to button 1 in the mousemap while the app tracks the mouse."""
 
     def run(self, edit, event):
-        """Focus the tab on the first click, report press and release after that."""
+        """Focus an inactive tab; else report the press and remember its cell."""
         terminal = Terminal.from_id(self.view.id())
         if not terminal:
             return
+        terminal.mouse_press = None  # a release may not come: the context can drop mid-drag
         window = self.view.window()
         if window and window.active_view() != self.view:
-            # we replaced drag_select, which is what focuses the group; this
-            # click only focuses, as clicking an unfocused terminal window does
+            # the mousemap binding displaces drag_select, which is what focuses
+            # the group; this click only focuses, as in a terminal window
             window.focus_view(self.view)
             return
         cell = _event_to_cell(self.view, terminal, event)
         if cell is None:
             return
+        terminal.mouse_press = cell
         terminal.send_mouse(0, cell[0], cell[1], pressed=True)
-        terminal.send_mouse(0, cell[0], cell[1], pressed=False)
+        # native drag_select only previews the selection while dragging; the
+        # app gets the real one at release
+        self.view.run_command("drag_select", {"event": event})
 
     def want_event(self):
         """Ask sublime for the click coordinates."""
         return True
 
 
+class VtermMouseReleaseCommand(sublime_plugin.TextCommand):
+    """Reports the release, after one drag motion when the button came up elsewhere.
+
+    Sublime raises no motion events, so a drag reaches the app as a single
+    move to the release cell; an app's selection then spans press to release.
+    The native preview selection goes, leaving the app's own highlight."""
+
+    def run(self, edit, event):
+        """Report motion and release for the pending press, if any."""
+        terminal = Terminal.from_id(self.view.id())
+        if not terminal or terminal.mouse_press is None:
+            return
+        cell = _event_to_cell(self.view, terminal, event, clamp=True)
+        if cell != terminal.mouse_press:
+            terminal.send_mouse(MOTION, cell[0], cell[1], pressed=True)
+        terminal.send_mouse(0, cell[0], cell[1], pressed=False)
+        terminal.mouse_press = None
+        self.view.sel().clear()
+        self.view.run_command("vterm_show_cursor", {"scroll": False})
+
+    def want_event(self):
+        """Ask sublime for the release coordinates."""
+        return True
+
+
 class VtermScrollCommand(sublime_plugin.TextCommand):
     """Bound to scroll wheel in the mousemap while the app tracks the mouse or is on the alt screen."""
 

vterm/terminal.py

@@ -121,6 +121,8 @@ class Terminal:
         # guards the queue/flag handoff between send_string and the drain thread
         self._send_lock = threading.Lock()
         self._wheel_captured = False
+        self._mouse_reporting = False
+        self.mouse_press = None  # cell of the pending button-1 press, for the release report
         self._scroll_pending = False
         self.pending_clear = False
         self.pending_clear_screen = False
@@ -329,7 +331,7 @@ class Terminal:
                             if frames >= UNDO_CLEAR_FRAMES:
                                 frames = 0
                                 self.view.run_command("vterm_clear_undo_stack")
-                    self._sync_wheel_flag()
+                    self._sync_mouse_flags()
                     if done[0] or not self.is_hosted():
                         LOG.debug("[renderer] stops")
                         break
@@ -425,12 +427,16 @@ class Terminal:
                 continue
             self.process.write(string)
 
-    def _sync_wheel_flag(self):
-        """Publish whether the app owns the wheel, for the mousemap context."""
-        captured = self.screen.mouse_reporting_enabled() or self.screen.alternate_buffer_mode
+    def _sync_mouse_flags(self):
+        """Publish whether the app owns the wheel and the mouse, for the mousemap contexts."""
+        reporting = self.screen.mouse_reporting_enabled()
+        captured = reporting or self.screen.alternate_buffer_mode
         if captured != self._wheel_captured:
             self._wheel_captured = captured
             self.view.settings().set("vterm_view.wheel_captured", captured)
+        if reporting != self._mouse_reporting:
+            self._mouse_reporting = reporting
+            self.view.settings().set("vterm_view.mouse_reporting", reporting)
 
     def send_focus(self, focused):
         """Report focus gain or loss, when the app asked for it (?1004)."""