How do I paint a texture stencil onto an object with Python?

Question

I'm trying to paint an image texture onto an object with bpy. I'm not running in background mode, so I can confirm the following:

1. Object is loaded
2. Image texture is loaded and added as a slot on the brush
3. Image texture is set to stencil mode
4. Image texture stencil is aligned with the mesh after some re-jiggering of the viewport (I can confirm this when the command line opens a blender window).

I now want to add strokes that paint the texture stencil onto the object, but having lots of trouble.

No matter what I do, the strokes don't show up on my object. However, I can easily paint the texture on manually. What is going on??

Note -- I tried some simple strokes that cross the viewport -- those didn't work. Now trying various stroke areas. But very confused. The context is correct (it was complaining before about that...)

    def get_override(area_type, region_type):
        # Find the specified area and region
        for window in bpy.context.window_manager.windows:
            screen = window.screen
            for area in screen.areas:
                if area.type == area_type:
                    for region in area.regions:
                        if region.type == region_type:
                            override = {
                                'window': window,
                                'screen': screen,
                                'area': area,
                                'region': region,
                                'space_data': area.spaces.active,
                                'blend_data': bpy.context.blend_data,
                                'scene': bpy.context.scene,
                                'tool_settings': bpy.context.tool_settings,
                                'view_layer': bpy.context.view_layer,
                                'workspace': bpy.context.workspace,
                                'region_data': area.spaces.active.region_3d if area.type == 'VIEW_3D' else None
                            }
                            return override
        return None
    override = get_override( 'VIEW_3D', 'WINDOW')
    bpy.ops.object.editmode_toggle()
    bpy.ops.paint.texture_paint_toggle()

    # Define the strokes to cover the viewport
    strokes = []
    for i in range(10):
        start_y = 500 + (i * 100)
        end_y = 500 + (i * 100)
        strokes.append({
            "name": f"stroke{i * 2 + 1}",
            "mouse": (0, start_y),  # Starting point in the viewport
            "mouse_event": (0, start_y),  # Starting point in the viewport
            "location": (0, 0, 0),  # Starting 3D location
            "pressure": 1.0,
            "size": 50,
            "pen_flip": False,
            "time": 1.0,
            "x_tilt": 0.0,
            "y_tilt": 0.0,
            "is_start": True,
        })
        strokes.append({
            "name": f"stroke{i * 2 + 2}",
            "mouse": (2000, end_y),  # Ending point in the viewport
            "mouse_event": (2000, end_y),  # Ending point in the viewport
            "location": (0, 0, 0),  # Ending 3D location
            "pressure": 1.0,
            "size": 50,
            "pen_flip": False,
            "time": 1.0,
            "x_tilt": 0.0,
            "y_tilt": 0.0,
            "is_start": False,
        })

    with bpy.context.temp_override(window=override['window'], screen=override['screen'], area=override['area'], region=override['region']):
        # print_context(    bpy.context)
        result = bpy.ops.paint.image_paint(stroke=strokes, mode='NORMAL')
        

Here's what I'm trying to do (the painted strokes were done manually):