fix(engine): prefs.set and prefs.reset apply the text blending gamma (#987) (#1709)

crates/engine/src/prefs.rs

@@ -1410,6 +1410,8 @@ fn prefs_set(s: &mut Session, p: &Value) -> Result<Value> {
             return Err(bad(cmd, e));
         }
     }
+    // `colorSettings.blendTextGamma` lives in the compositor too, as `edit.colorSettings` sets it.
+    photocraft_compose::psblend::set_text_gamma(s.color.settings.blend_text_gamma);
     s.apply_prefs();
     let view = s.prefs_view();
     let out: Map<String, Value> = changes.iter().map(|(k, _)| (k.clone(), get_path(&view, k).cloned().unwrap_or(Value::Null))).collect();
@@ -1439,6 +1441,7 @@ fn prefs_reset(s: &mut Session, p: &Value) -> Result<Value> {
         }
     }
     s.prefs.edit(|_| ());
+    photocraft_compose::psblend::set_text_gamma(s.color.settings.blend_text_gamma);
     s.apply_prefs();
     if path.is_some_and(|path| keyed(path).is_some()) {
         // The removed override is absent, so reading its old path would report an error.

crates/engine/tests/text_gamma.rs

@@ -27,4 +27,21 @@ fn blend_text_gamma_setting() {
     s.execute("edit.colorSettings", json!({"blendTextGamma": true})).unwrap();
     assert!((s.color.settings.blend_text_gamma - 1.45).abs() < 1e-6);
     assert!((photocraft_compose::psblend::text_gamma() - 1.45).abs() < 1e-6);
+
+    // `prefs.set` and `prefs.reset` on `colorSettings` move the compositor's gamma too (#987).
+    // Same function, not a second test: tests in one binary run concurrently.
+    let in_sync = |s: &Session| (photocraft_compose::psblend::text_gamma() - s.color.settings.blend_text_gamma).abs() < 1e-6;
+    s.execute("edit.colorSettings", json!({"blendTextGamma": 1.8})).unwrap();
+    s.execute("prefs.set", json!({"path": "colorSettings.blendTextGamma", "value": 1.0})).unwrap();
+    assert_eq!(photocraft_compose::psblend::text_gamma(), 1.0);
+    assert!(in_sync(&s));
+    s.execute("prefs.reset", json!({"path": "colorSettings.blendTextGamma"})).unwrap();
+    assert!((photocraft_compose::psblend::text_gamma() - 1.45).abs() < 1e-6);
+    assert!(in_sync(&s));
+    for reset in [json!({"path": "colorSettings"}), json!({})] {
+        s.execute("edit.colorSettings", json!({"blendTextGamma": 1.8})).unwrap();
+        s.execute("prefs.reset", reset).unwrap();
+        assert!((photocraft_compose::psblend::text_gamma() - 1.45).abs() < 1e-6);
+        assert!(in_sync(&s));
+    }
 }