fix(typography): Standard Ligatures switches on over a feature-list -liga

crates/engine/src/cmd/text.rs

@@ -1501,8 +1501,9 @@ fn open_type_features(s: &mut Session, _p: &Value) -> Result<Value> {
     let measure = |tag: &str| {
         let (mut applied, mut available) = (0, 0);
         for seg in &segments {
-            // Standard ligatures are the `ligatures` attribute, which shaping reads.
-            let on = if tag == "liga" { seg.ligatures } else { designcraft_doc::otf::is_on(&seg.applied, tag) };
+            // Standard ligatures are the `ligatures` attribute, which shaping reads, unless the
+            // feature list turns `liga` off.
+            let on = designcraft_doc::otf::is_on(&seg.applied, tag) && (tag != "liga" || seg.ligatures);
             if on {
                 applied += seg.len;
             }
@@ -2844,6 +2845,9 @@ mod open_type_features_tests {
         s.execute("type.char", &json!({"attrs": {"ligatures": true}})).unwrap();
         let v = s.execute("type.openTypeFeatures", &json!({})).unwrap();
         assert_eq!(feature(&v, "liga")["applied"], "all", "{v}");
+        s.execute("type.feature", &json!({"features": {"liga": false}})).unwrap();
+        let v = s.execute("type.openTypeFeatures", &json!({})).unwrap();
+        assert_eq!(feature(&v, "liga")["applied"], "none", "-liga in the feature list: {v}");
     }
 }
 

crates/ui-egui/src/panels/typography.rs

@@ -92,10 +92,12 @@ struct Changes {
 
 impl Changes {
     /// Standard Ligatures is the `ligatures` attribute: shaping turns `liga` off through it, and
-    /// IDML carries it as `Ligatures`, so `liga` stays out of the feature list.
+    /// IDML carries it as `Ligatures`, so `liga` stays out of the feature list. The tag is also
+    /// cleared from the selection's features, since an earlier `-liga` would keep shaping it off.
     fn set(&mut self, tag: &str, on: bool) {
         if tag == "liga" {
             self.ligatures = Some(on);
+            self.features.insert("liga".to_string(), true);
         } else {
             self.features.insert(tag.to_string(), on);
         }
@@ -396,4 +398,16 @@ mod tests {
         click(&mut h, "Standard Ligatures");
         assert_eq!(chars(&mut h)["ligatures"], true, "the switch turns ligatures back on");
     }
+
+    #[test]
+    fn standard_ligatures_switch_on_clears_a_feature_list_liga_off() {
+        let mut h = harness();
+        h.state_mut().run("type.feature", json!({"features": {"liga": false}})).unwrap();
+        assert_eq!(chars(&mut h)["otfFeatures"], json!(["-liga"]));
+        h.run_steps(2);
+        click(&mut h, "Standard Ligatures");
+        let c = chars(&mut h);
+        assert_eq!(c["ligatures"], true, "{c}");
+        assert!(!c["otfFeatures"].as_array().is_some_and(|l| l.iter().any(|t| t.as_str().is_some_and(|t| t.ends_with("liga")))), "{c}");
+    }
 }