Reject negative and fractional indexes in node.reorder

Found while testing crates/engine/src/cmd/edit.rs:329

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

crates/engine/src/al_nesting_tests.rs

@@ -345,3 +345,16 @@ fn remove_all_auto_layout_strips_the_frame_and_every_frame_nested_in_it() {
     s.execute("edit.undo", &json!({})).unwrap();
     assert_eq!(laid_out(&s), [true, true, true]);
 }
+
+#[test]
+fn reorder_rejects_negative_and_fractional_indexes() {
+    let mut s = Session::new();
+    let f = frame(&mut s, None, 0.0, 0.0, 200.0, 200.0);
+    let a = rect(&mut s, Some(f), 0.0, 0.0, 10.0, 10.0);
+    let b = rect(&mut s, Some(f), 0.0, 0.0, 10.0, 10.0);
+    let c = rect(&mut s, Some(f), 0.0, 0.0, 10.0, 10.0);
+    for bad in [json!(-1), json!(0.5), json!("x")] {
+        assert!(s.execute("node.reorder", &json!({"id": c, "index": bad})).is_err(), "{bad} accepted");
+        assert_eq!(kids(&s, f), vec![a, b, c]);
+    }
+}

crates/engine/src/cmd/edit.rs

@@ -326,7 +326,7 @@ pub fn specs() -> Vec<CommandSpec> {
         ),
         spec!("node.reorder", "Reorder layer", "{id, index}", true, |s, p| {
             let i = req_id("node.reorder", p, "id")?;
-            let idx = req_num("node.reorder", p, "index")?.max(0.0) as usize;
+            let idx = req_index("node.reorder", p, "index")?;
             s.doc_mut()?.reorder(i, idx)?;
             ok()
         }),