Object styles: a stroke tint outside 0..1 is refused

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

crates/engine/src/cmd/style.rs

@@ -1536,13 +1536,16 @@ fn create_object(s: &mut Session, p: &Value) -> Result<Value> {
 }
 
 /// `p.stroke` merged over `base` (as [`group_param`]), refused when the weight isn't a number ≥ 0
-/// or the tint isn't finite.
+/// or the tint isn't 0–1.
 fn stroke_param(cmd: &str, p: &Value, base: Option<&designcraft_doc::Stroke>) -> Result<Option<Option<designcraft_doc::Stroke>>> {
     let st = group_param(cmd, p, "stroke", base.unwrap_or(&designcraft_doc::Stroke::default()))?;
-    if let Some(Some(st)) = &st
-        && !(st.weight.is_finite() && st.weight >= 0.0 && st.tint.is_finite())
-    {
-        return Err(bad(cmd, "stroke weight must be a number ≥ 0"));
+    if let Some(Some(st)) = &st {
+        if !(st.weight.is_finite() && st.weight >= 0.0) {
+            return Err(bad(cmd, "stroke weight must be a number ≥ 0"));
+        }
+        if !(0.0..=1.0).contains(&st.tint) {
+            return Err(bad(cmd, "stroke tint must be 0..1"));
+        }
     }
     Ok(st)
 }

crates/engine/src/tests.rs

@@ -730,6 +730,10 @@ fn object_styles_carry_corners_and_their_stroke_and_corners_can_be_edited() {
     for cmd in ["style.object.create", "style.object.edit"] {
         let e = s.execute(cmd, &json!({"name": "Framed", "stroke": {"weight": -3}})).unwrap_err();
         assert!(e.to_string().contains("stroke weight"), "{cmd}: {e}");
+        for tint in [-1.0, 1.5] {
+            let e = s.execute(cmd, &json!({"name": "Framed", "stroke": {"tint": tint}})).unwrap_err();
+            assert!(e.to_string().contains("stroke tint"), "{cmd}: {e}");
+        }
     }
     assert_eq!(s.doc().unwrap().doc.styles.object.len(), styles);
     // null: the style stops setting corners, the items keep theirs.