Color: rgb_to_hsl keeps over-range saturation so 32 bpc colours round-trip

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

crates/color/src/lib.rs

@@ -99,7 +99,7 @@ pub fn rgb_to_hsl(r: f32, g: f32, b: f32) -> (f32, f32, f32) {
     let d = max - min;
     let denom = if l > 0.5 { 2.0 - max - min } else { max + min };
     // Over-range (HDR) or negative inputs can make the denominator zero or negative.
-    let s = if denom > 0.0 { (d / denom).min(1.0) } else { 1.0 };
+    let s = if denom > 0.0 { d / denom } else { 1.0 };
     let h = if max == r {
         (((g - b) / d + if g < b { 6.0 } else { 0.0 }) / 6.0).rem_euclid(1.0)
     } else if max == g {
@@ -269,10 +269,13 @@ mod tests {
         for (r, g, b) in [(1.5, 0.5, 0.5), (2.0, 0.1, 0.3), (-0.5, 0.2, 0.9)] {
             let (h, s, l) = rgb_to_hsl(r, g, b);
             assert!(h.is_finite() && s.is_finite() && l.is_finite(), "{h} {s} {l}");
-            assert!((0.0..=1.0).contains(&s), "saturation {s} for {r} {g} {b}");
             let (r2, g2, b2) = hsl_to_rgb(h, s, l);
             assert!(r2.is_finite() && g2.is_finite() && b2.is_finite(), "{r2} {g2} {b2}");
         }
+        // A 32 bpc colour whose denominator stays positive still round-trips exactly.
+        let (h, s, l) = rgb_to_hsl(1.2, 0.5, 0.5);
+        let (r, g, b) = hsl_to_rgb(h, s, l);
+        assert!((r - 1.2).abs() < 1e-5 && (g - 0.5).abs() < 1e-5 && (b - 0.5).abs() < 1e-5, "{r} {g} {b}");
     }
 
     #[test]