prefs.reset resets a single colorSettings key (#445) (#467)

`prefs.get` and `prefs.set` route `colorSettings.*` to the colour state,
but `prefs.reset` only special-cased the whole section. A nested path
fell through to `Preferences::reset`, which has no colorSettings, so it
failed with "unknown preference". Take the default from
`ColorSettings::default()` and set it the way `prefs.set` does.

Co-authored-by: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

crates/engine/src/prefs.rs

@@ -1351,6 +1351,14 @@ fn prefs_reset(s: &mut Session, p: &Value) -> Result<Value> {
     let path = p.get("path").or_else(|| p.get("section")).and_then(Value::as_str);
     match path {
         Some("colorSettings") => s.color.settings = Default::default(),
+        // One colour setting: `Preferences` has no `colorSettings`, so take the default
+        // from `ColorSettings` and route it like `prefs.set` does.
+        Some(path) if path.starts_with("colorSettings.") => {
+            let defaults = serde_json::to_value(crate::color_cmds::ColorSettings::default()).map_err(|e| bad("prefs.reset", e.to_string()))?;
+            let key = path.strip_prefix("colorSettings.").unwrap_or(path);
+            let def = get_path(&defaults, key).cloned().ok_or_else(|| bad("prefs.reset", format!("unknown preference `{path}`")))?;
+            s.set_pref(path, def).map_err(|e| bad("prefs.reset", e))?;
+        }
         None => {
             s.color.settings = Default::default();
             s.edit_prefs(|p| p.reset(None)).map_err(|e| bad("prefs.reset", e))?;

crates/engine/src/prefs/tests.rs

@@ -45,6 +45,18 @@ fn get_set_reset_by_path() {
     assert_eq!(s.active().unwrap().history.max_states, 50);
 }
 
+#[test]
+fn reset_one_colour_setting() {
+    let mut s = session();
+    s.execute("prefs.set", json!({"values": {"colorSettings.bpc": false, "colorSettings.workingRgb": "display-p3"}})).unwrap();
+    assert_eq!(s.execute("prefs.reset", json!({"path": "colorSettings.bpc"})).unwrap(), json!(true));
+    assert!(s.color.settings.bpc);
+    assert_eq!(s.color.settings.working_rgb, "display-p3", "other colour settings are untouched");
+    s.execute("prefs.reset", json!({"path": "colorSettings.workingRgb"})).unwrap();
+    assert_eq!(s.color.settings, crate::color_cmds::ColorSettings::default());
+    assert!(s.execute("prefs.reset", json!({"path": "colorSettings.notAField"})).is_err());
+}
+
 #[test]
 fn set_validates_and_is_all_or_nothing() {
     let mut s = session();