bare-low/claude-sonnet-4-6 / tier-2-l-bracket

```openscad
// L-Bracket

// Parameters
w = 50;   // width (X)
hf = 40;  // horizontal flange depth (Y)
vf = 40;  // vertical flange height (Z)
t = 3;    // thickness

// Hole parameters
hole_d = 4.5;
cs_d = 8;
cs_depth = 2;
hole_offset_edge = 10;  // from edge along flange direction
hole_offset_side = w/2 - (w/4); // left/right: symmetric, at w/4 from center each side
// holes at X = -w/4 and X = +w/4 ... actually "left-right symmetric, 2 holes"
// Let's place at X = ±(w/2 - 10) ... no, "center line, left-right symmetric 2 holes"
// "各面の中心線上で、面の縁から10mm内側、左右対称に2個"
// I'll interpret: along width, symmetric about center, at X = ±(w/4) 
// Actually let's use X = ±(w/2 - 10) for nice placement
hx1 = -(w/2 - 10);
hx2 =  (w/2 - 10);

module countersunk_hole_vertical(depth_total) {
    // hole along Z, countersink at top (Z = depth_total, i.e., outside face going down)
    // Used for horizontal flange: outside is -Z face
    union() {
        cylinder(h = depth_total, d = hole_d, $fn=32);
        translate([0, 0, -cs_depth])
            cylinder(h = cs_depth + 0.01, d1 = cs_d, d2 = hole_d, $fn=32);
    }
}

module countersunk_hole_horizontal(depth_total) {
    // hole along Y, countersink at -Y face (outside of vertical flange)
    union() {
        cylinder(h = depth_total, d = hole_d, $fn=32);
        cylinder(h = cs_depth, d1 = cs_d, d2 = hole_d, $fn=32);
    }
}

difference() {
    union() {
        // Horizontal flange: extends in +Y, lies in XY plane, thickness in Z (0 to -t)
        translate([-w/2, 0, -t])
            cube([w, hf, t]);
        
        // Vertical flange: extends in +Z, lies in XZ plane, thickness in Y (0 to -t)  
        // Wait: inner corner at origin, vertical goes +Z, horizontal goes +Y
        // Vertical flange: X from -w/2 to w/2, Z from 0 to vf, Y from -t to 0
        translate([-w/2, -t, 0])
            cube([w, t, vf]);
    }
    
    // Holes in horizontal flange (along Z)
    // Outside face is at Z = -t (bottom), countersink opens downward
    // Holes at Y = hf - 10 (10mm from far edge), X = hx1, hx2
    for (hx = [hx1, hx2]) {
        translate([hx, hf - hole_offset_edge, 0]) {
            // drill from Z=0 down to Z=-t
            translate([0, 0, -t])
                union() {
                    cylinder(h = t, d = hole_d, $fn=32);
                    // countersink at bottom (outside = -t face)
                    cylinder(h = cs_depth, d1 = cs_d, d2 = hole_d, $fn=32);
                }
        }
    }
    
    // Holes in vertical flange (along Y)
    // Outside face is at Y = -t, countersink opens outward (-Y direction)
    // Holes at Z = vf - 10, X = hx1, hx2
    for (hx = [hx1, hx2]) {
        translate([hx, -t, vf - hole_offset_edge]) {
            rotate([-90, 0, 0]) {
                cylinder(h = t, d = hole_d, $fn=32);
                // countersink at start (Y = -t face, outside)
                cylinder(h = cs_depth, d1 = cs_d, d2 = hole_d, $fn=32);
            }
        }
    }
}
```