Use ConfigKit mapping values directly

profiles.go

@@ -25,7 +25,8 @@ type ProfileConfig struct {
 // It encodes fields without validating them; NewEngine validates the final
 // effective configuration after all selected source layers are combined.
 // Mapping captures a copy of supported input values at creation; unsupported
-// values fail when the source is loaded.
+// values fail when the source is loaded. ExtraParams must use ConfigKit Mapping
+// input forms; callers must explicitly convert numbers or containers as needed.
 func ProfileSource(label string, profiles []ProfileConfig) configkit.Source {
 	definitions := make([]any, 0, len(profiles))
 	for _, config := range profiles {
@@ -67,7 +68,7 @@ func ProfileSource(label string, profiles []ProfileConfig) configkit.Source {
 			fields["api_key_required"] = *config.APIKeyRequired
 		}
 		if config.ExtraParams != nil {
-			fields["extra_params"] = providerMapForMapping(config.ExtraParams)
+			fields["extra_params"] = config.ExtraParams
 		}
 		definitions = append(definitions, fields)
 	}