Fix LISP getangle subtracting ANGBASE in degrees from radians (#1883)

Found while testing crates/engine/src/lisp/input.rs:256-258 (lisp_angbase, used at :127 and :183); cause is crates/engine/src/sysvars.rs:141

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

crates/engine/src/lisp/input.rs

@@ -260,7 +260,7 @@ fn keyword(keywords: &[String], t: &str) -> Option<String> {
 impl Session {
     /// ANGBASE (radians).
     fn lisp_angbase(&self) -> f64 {
-        crate::sysvars::get(self, "ANGBASE").and_then(|v| v.as_f64()).unwrap_or(0.0)
+        self.doc().map(|d| d.header.f64("ANGBASE", 0.0)).unwrap_or(0.0)
     }
 }
 

crates/engine/src/lisp/tests.rs

@@ -497,6 +497,24 @@ fn interactive_routine_waits_for_the_user() {
     assert!(s.doc().unwrap().model.iter().any(|e| matches!(&e.kind, cadcraft_doc::EntityKind::Circle(c) if c.center.x == 50.0 && c.radius == 2.0)));
 }
 
+#[test]
+fn getangle_is_relative_to_angbase() {
+    let mut s = session();
+    s.cmdline("(setvar \"ANGBASE\" 90)").unwrap();
+    // A picked point at 180° in world terms is 90° from ANGBASE.
+    s.cmdline("(setq a (getangle '(0 0)))").unwrap();
+    s.input(crate::Input::Point(cadcraft_geom::Vec2::new(-1.0, 0.0))).unwrap();
+    assert_eq!(to_text(&s.lisp_var("A"), true), "1.5708");
+    // getorient ignores ANGBASE.
+    s.cmdline("(setq o (getorient '(0 0)))").unwrap();
+    s.input(crate::Input::Point(cadcraft_geom::Vec2::new(-1.0, 0.0))).unwrap();
+    assert_eq!(to_text(&s.lisp_var("O"), true), "3.14159");
+    // A typed angle is already measured from ANGBASE.
+    s.cmdline("(setq t2 (getangle))").unwrap();
+    s.cmdline("180").unwrap();
+    assert_eq!(to_text(&s.lisp_var("T2"), true), "3.14159");
+}
+
 #[test]
 fn appload_and_load() {
     let mut s = session();