SETVAR keeps text variables such as CLAYER as text, so a layer named 10 can be selected (#484) (#576)

Squash of PR #576 by @MarekSpodBiedry.

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

crates/engine/src/sysvars.rs

@@ -297,6 +297,16 @@ pub fn set(s: &mut Session, name: &str, v: &Value) -> Result<()> {
                     d.header.set_i64(&n, i);
                     return Ok(());
                 }
+                // A text variable (CLAYER...) keeps what was typed, so a layer named `10` stays a string.
+                Some(cadcraft_doc::HVal::Str(_)) => {
+                    let text = match v {
+                        Value::String(t) => t.clone(),
+                        Value::Number(x) => x.to_string(),
+                        _ => return Err(bad()),
+                    };
+                    d.header.set(&n, cadcraft_doc::HVal::Str(text));
+                    return Ok(());
+                }
                 // A point variable takes `x,y` typed at the command line too.
                 Some(cadcraft_doc::HVal::Point(_)) => {
                     d.header.set(&n, cadcraft_doc::HVal::Point(as_pt(v).ok_or_else(bad)?.to3(0.0)));

crates/engine/src/tests.rs

@@ -471,6 +471,26 @@ fn sysvars_roundtrip() {
     assert_eq!(sysvars::get(&s, "FONTALT"), Some(json!("")));
 }
 
+#[test]
+fn setvar_clayer_keeps_numeric_layer_name() {
+    let mut s = Session::new();
+    s.execute("layer.new", &json!({"name": "10"})).unwrap();
+    s.execute("setvar", &json!({"name": "CLAYER", "value": "10"})).unwrap();
+    assert_eq!(sysvars::get(&s, "CLAYER"), Some(json!("10")));
+    let c = s.execute("circle", &json!({"center": [0, 0], "radius": 1})).unwrap();
+    let h = cadcraft_doc::Handle::parse_hex(c["handle"].as_str().unwrap()).unwrap();
+    assert_eq!(s.doc().unwrap().entity(h).unwrap().common.layer, "10");
+    s.execute("setvar", &json!({"name": "CLAYER", "value": "0"})).unwrap();
+    assert_eq!(sysvars::get(&s, "CLAYER"), Some(json!("0")));
+    // Typed at the command line too.
+    s.cmdline("SETVAR CLAYER 10").unwrap();
+    assert!(s.running.is_none());
+    assert_eq!(sysvars::get(&s, "CLAYER"), Some(json!("10")));
+    // Numeric variables still parse typed text.
+    s.execute("setvar", &json!({"name": "LUNITS", "value": "3"})).unwrap();
+    assert_eq!(sysvars::get(&s, "LUNITS"), Some(json!(3)));
+}
+
 #[test]
 fn setvar_at_command_line() {
     let mut s = Session::new();