bare-high/gpt-5 / tier-2-l-bracket

```openscad
// L-bracket with counterbored holes
width = 50;      // X: plate width
length = 40;     // Y (horizontal depth) / Z (vertical height)
thickness = 3;

hole_d = 4.5;        // through-hole diameter
cbore_d = 8;         // counterbore diameter
cbore_depth = 2;     // counterbore depth
edge_inset = 10;     // inset from side edges along X
$fn = 64;
eps = 0.01;

module ycyl(d, h) { rotate([-90, 0, 0]) cylinder(d=d, h=h, center=false); }

module l_bracket() {
  translate([-width/2, 0, 0])
  difference() {
    // Base geometry: inner corner at (x: any, y=0, z=0), flanges to +Y and +Z
    union() {
      // Horizontal flange (extends +Y)
      cube([width, length, thickness], center=false);
      // Vertical flange (extends +Z)
      cube([width, thickness, length], center=false);
    }

    // Holes on horizontal flange (counterbore on top, z = thickness side)
    for (sx = [-1, 1]) {
      x = width/2 + sx*(width/2 - edge_inset);
      y = length/2;
      // Through hole
      translate([x, y, -eps]) cylinder(d=hole_d, h=thickness + 2*eps);
      // Counterbore (from outer/top face)
      translate([x, y, thickness - cbore_depth - eps])
        cylinder(d=cbore_d, h=cbore_depth + 2*eps);
    }

    // Holes on vertical flange (counterbore on outer side, y = thickness side)
    for (sx = [-1, 1]) {
      x = width/2 + sx*(width/2 - edge_inset);
      z = length/2;
      // Through hole along Y
      translate([x, -eps, z]) ycyl(d=hole_d, h=thickness + 2*eps);
      // Counterbore from outer face (y = thickness)
      translate([x, thickness - cbore_depth - eps, z])
        ycyl(d=cbore_d, h=cbore_depth + 2*eps);
    }
  }
}

l_bracket();
```