Adds some snap helpers to split windows to the left in various ways

core/windows_and_tabs/window_management.talon

@@ -17,5 +17,7 @@ snap last [screen]: user.move_window_previous_screen()
 snap screen <number>: user.move_window_to_screen(number)
 snap <user.running_applications> <user.window_snap_position>:
     user.snap_app(running_applications, window_snap_position)
+snap <user.window_split_position> <user.running_applications> <user.running_applications>+:
+    user.snap_layout(window_split_position, running_applications_list)
 snap <user.running_applications> [screen] <number>:
     user.move_app_to_screen(running_applications, number)

core/windows_and_tabs/window_snap.py

@@ -8,7 +8,7 @@
 #   platforms
 
 import logging
-from typing import Optional
+from typing import Dict, Optional
 
 from talon import Context, Module, actions, settings, ui
 
@@ -17,6 +17,10 @@
     "window_snap_positions",
     "Predefined window positions for the current window. See `RelativeScreenPos`.",
 )
+mod.list(
+    "window_split_positions",
+    "Predefined window positions when splitting the screen between three applications.",
+)
 mod.setting(
     "window_snap_screen",
     type=str,
@@ -272,14 +276,47 @@ def __init__(self, left, top, right, bottom):
     "fullscreen": RelativeScreenPos(0, 0, 1, 1),
 }
 
+_split_positions = {
+    "split": {
+        2: [_snap_positions["left"], _snap_positions["right"]],
+        3: [
+            _snap_positions["left third"],
+            _snap_positions["center third"],
+            _snap_positions["right third"],
+        ],
+    },
+    "clock": {
+        2: [_snap_positions["left"], _snap_positions["right"]],
+        3: [
+            _snap_positions["left"],
+            _snap_positions["top right"],
+            _snap_positions["bottom right"],
+        ],
+    },
+    "counterclock": {
+        2: [_snap_positions["left"], _snap_positions["right"]],
+        3: [
+            _snap_positions["right"],
+            _snap_positions["top left"],
+            _snap_positions["bottom left"],
+        ],
+    },
+}
+
 
 @mod.capture(rule="{user.window_snap_positions}")
 def window_snap_position(m) -> RelativeScreenPos:
     return _snap_positions[m.window_snap_positions]
 
 
+@mod.capture(rule="{user.window_split_positions}")
+def window_split_position(m) -> Dict[int, list[RelativeScreenPos]]:
+    return _split_positions[m.window_split_positions]
+
+
 ctx = Context()
 ctx.lists["user.window_snap_positions"] = _snap_positions.keys()
+ctx.lists["user.window_split_positions"] = _split_positions.keys()
 
 
 @mod.action_class
@@ -310,6 +347,22 @@ def snap_app(app_name: str, position: RelativeScreenPos):
         _bring_forward(window)
         _snap_window_helper(window, position)
 
+    def snap_layout(
+        positions_by_count: Dict[int, list[RelativeScreenPos]],
+        apps: list[str],
+    ):
+        """Split the screen between multiple applications."""
+        try:
+            positions = positions_by_count[len(apps)]
+        except KeyError:
+            raise NotImplementedError(
+                f"There is no such layout yet defined for {len(apps)} items"
+            )
+        for index, app in enumerate(apps):
+            window = _get_app_window(app)
+            _snap_window_helper(window, positions[index])
+            window.focus()
+
     def move_app_to_screen(app_name: str, screen_number: int):
         """Move a specific application to another screen."""
         window = _get_app_window(app_name)