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

```openscad
// Mug (OD 80, ID 70, wall 5, height 90, bottom thickness 6)
// +X side only D-handle (hollow), manifold-safe union

$fn = 180;

// --- Mug params ---
outer_d   = 80;
inner_d   = 70;
h_mug     = 90;
t_bottom  = 6;

mug_outer_r = outer_d/2; // 40
mug_inner_r = inner_d/2; // 35

// --- Handle params ---
handle_inner_w = 25;     // inner space width (Y)
handle_inner_h = 30;     // inner space height (Z)
handle_center_z = h_mug/2; // around middle

handle_depth = 22;       // extrusion depth along +X
handle_shell = 4;        // handle shell thickness (radial in YZ)

// D cross-section definition in YZ:
// - D is "outer half-circle + flat line" (flat at Y = 0, bulge to +Y)
// - Inner void is another D scaled by handle_shell
// - Then overall handle is clipped by a rectangle to ensure exact void (Y width, Z height).
module d_shell_2d(r_outer, r_inner, y_void_max, z_void_min, z_void_max) {
  // 2D D surfaces (in YZ plane):
  // Outer D: semicircle bulging +Y with flat at Y=0
  // Inner D: semicircle bulging +Y with flat at Y=0
  module semicircle_with_flat_2d(r) {
    // returns polygon in (Y,Z), flat edge at Y=0, centered in Z around 0, bulge +Y
    pts = [
      for (i=[0:120])
        let(
          a = -90 + i*(180/120),
          y = r*cos(a),  // 0..r
          z = r*sin(a)   // -r..r
        )
        [y,z]
    ];
    // close the flat edge
    polygon(concat(pts, [[0,-r],[0,r]]));
  }

  // Build 2D handle shell as difference of outer minus inner,
  // then clip in Y and Z to get intended void dimensions.
  // Note: clipping is performed after 3D extrusion in the caller using a box.
  difference() {
    semicircle_with_flat_2d(r_outer);
    semicircle_with_flat_2d(r_inner);
  }
}

// 3D D-handle shell with exact hollow void size.
// Local coordinate system:
// - Mug axis: X
// - Y is tangential around mug
// - Z is vertical
// Local origin for handle placement: at (x = mug_outer_r) plane will be handled outside.
module handle_d() {
  // We set inner D semicircle radius so that its max width matches handle_inner_w.
  // For a semicircle with flat at Y=0, the bulge extent in Y equals radius.
  // So bulge extent should be handle_inner_w. That means r_inner = handle_inner_w.
  // But we also need a rectangular hole width; we'll clip hole exactly anyway.
  // We'll use r_inner = handle_inner_w/2 only if void width is measured flat-to-flat.
  // The prompt states "幅25mm" for the inner space; typical interpretation here:
  // the maximum Y spread equals 25. We'll satisfy that by using r_inner=25.
  r_inner = handle_inner_w;
  r_outer = r_inner + handle_shell;

  // Z void extents:
  z0 = handle_center_z - handle_inner_h/2;
  z1 = handle_center_z + handle_inner_h/2;

  // Local Z centered at 0 for D shapes; we will shift the local geometry by z0 later.
  // Create shell in local coordinates where Z center=0.
  // Then cut exact Z range and Y range using boxes.

  difference() {
    // Outer shell extruded along +X from x=0..handle_depth
    translate([0,0,z0])
      linear_extrude(height=handle_depth, center=false)
        d_shell_2d(r_outer=r_outer, r_inner=r_inner,
                   y_void_max=handle_inner_w,
                   z_void_min=z0, z_void_max=z1);

    // Inner void exact cut: subtract rectangle "void window" from within the D shell
    // so that interior space is height 30 and width 25.
    // We'll cut in a way that results in a D-shaped cavity (semi-circle + flat)
    // but bounded to the requested dimensions.
    translate([-1, -100, z0 - 0.5])
      cube([handle_depth + 2, 200, handle_inner_h + 1], center=false);

    // Additionally, ensure the handle cavity doesn't create negative-Y extension beyond flat side.
    // (Flat side at Y=0 in the D cross-section.)
    // Cut everything at Y<0 within the handle depth.
    translate([-1, -100, z0 - 0.5])
      cube([handle_depth + 2, 100, handle_inner_h + 1], center=false);
  }
}

// Mug body (solid cup with hollow interior)
module mug_body() {
  difference() {
    cylinder(d=outer_d, h=h_mug, center=false);
    // Subtract inner cylinder leaving bottom thickness t_bottom
    translate([0,0,t_bottom])
      cylinder(d=inner_d, h=h_mug - t_bottom, center=false);
  }
}

module mug_with_handle() {
  // Place handle on +X side only.
  // We position handle starting at x = mug_outer_r - small_eps so it unions reliably.
  // Then we clip to x>=mug_outer_r to avoid showing on -X.
  small_eps = 0.6;

  union() {
    mug_body();

    // Handle placement:
    // local handle_d() is built with x from 0..handle_depth.
    // We'll translate it so that x=0 is at the mug outer surface plane (x=mug_outer_r).
    translate([mug_outer_r - small_eps, 0, 0])
      intersection() {
        handle_d();
        // Keep only +X side region
        translate([-(mug_outer_r - small_eps), 0, 0])
          cube([mug_outer_r*2, 200, h_mug + 60], center=false);
      }
  }
}

// Ensure manifoldness by using a single union at top level
mug_with_handle();
```