iter-png-3/gpt-5.4 / tier-2-offset-handle-mug

```openscad
$fn = 128;

// Mug dimensions
outer_d   = 80;
inner_d   = 70;
mug_h     = 90;
bottom_t  = 6;

// Handle opening (clear space)
handle_open_w = 25;   // width in radial direction
handle_open_h = 30;   // height in Z direction

// Handle thickness / depth
handle_t = 5;         // band thickness and Y extrusion thickness

// Derived
outer_r = outer_d / 2;
inner_r = inner_d / 2;

handle_outer_h = handle_open_h + 2 * handle_t;   // 40
handle_outer_w = handle_open_w + handle_t;       // 30
handle_center_z = mug_h / 2;

// 2D D-shape with flat side on the left, round side on the right
module d_shape_2d(total_w, total_h) {
    r = total_h / 2;
    rect_w = total_w - r;
    union() {
        translate([0, -r])
            square([rect_w, total_h], center = false);
        translate([rect_w, 0])
            circle(r = r);
    }
}

module mug_body() {
    difference() {
        cylinder(h = mug_h, r = outer_r);
        translate([0, 0, bottom_t])
            cylinder(h = mug_h - bottom_t + 0.01, r = inner_r);
    }
}

module handle() {
    // Put the D shape in XZ plane and extrude along Y.
    // Flat side intersects the mug body to guarantee a solid manifold union.
    translate([outer_r - handle_t, 0, handle_center_z])
    rotate([90, 0, 0])
    difference() {
        linear_extrude(height = handle_t, center = true)
            d_shape_2d(handle_outer_w, handle_outer_h);

        translate([handle_t, 0, 0])
            linear_extrude(height = handle_t + 2, center = true)
                d_shape_2d(handle_open_w, handle_open_h);
    }
}

union() {
    mug_body();
    handle();
}
```