From f790e057787b3e8c05a373ad4c7195f2ea7cb967 Mon Sep 17 00:00:00 2001
From: NetterSilver <133535268+Silvertree2010@users.noreply.github.com>
Date: Sun, 25 Oct 2026 09:32:10 +0000
Subject: [PATCH] Keep hue below 360 in rgb_to_hsv and rgb_to_hsl

Found while testing crates/color/src/perceptual.rs:129 (hue_of)

Co-Authored-By: Claude Haiku 5.5 <noreply@anthropic.com>
Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
---
 crates/color/src/perceptual.rs | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/crates/color/src/perceptual.rs b/crates/color/src/perceptual.rs
index 78824321c..fb5b89b75 100644
--- a/crates/color/src/perceptual.rs
+++ b/crates/color/src/perceptual.rs
@@ -132,7 +132,9 @@ fn hue_of(c: [f32; 3], max: f32, d: f32) -> f32 {
     } else {
         (c[0] - c[1]) / d + 4.0
     };
-    h * 60.0
+    let deg = h * 60.0;
+    // rem_euclid can round up to exactly 6.0 in f32; keep the range [0, 360).
+    if deg >= 360.0 { 0.0 } else { deg }
 }
 
 #[cfg(test)]
@@ -173,4 +175,11 @@ mod tests {
         }
         assert_eq!(rgb_to_hsv([0.0, 1.0, 0.0])[0], 120.0);
     }
+
+    #[test]
+    fn hue_below_360_for_tiny_blue() {
+        let c = [1.0, 0.0, 1e-9];
+        assert!(rgb_to_hsv(c)[0] < 360.0, "hsv hue {}", rgb_to_hsv(c)[0]);
+        assert!(rgb_to_hsl(c)[0] < 360.0, "hsl hue {}", rgb_to_hsl(c)[0]);
+    }
 }