tools: align locale diagnostics and generate native language names

tools/preview/engine.go

@@ -20,16 +20,17 @@ import (
 )
 
 type PreviewResult struct {
-	Rendered  map[string]map[string]map[string]string
-	Registry  map[string]map[string]string
-	Params    map[string]map[string]string
-	Languages []string
-	Themes    []string
-	Upstream  string
-	Commit    string
-	Logo      []byte
-	Fallback  map[string][]string
-	Warnings  map[string]map[string][]string
+	Rendered      map[string]map[string]map[string]string
+	Registry      map[string]map[string]string
+	Params        map[string]map[string]string
+	Languages     []string
+	LanguageNames map[string]string
+	Themes        []string
+	Upstream      string
+	Commit        string
+	Logo          []byte
+	Fallback      map[string][]string
+	Warnings      map[string]map[string][]string
 }
 
 func DiscoverThemes(dir string) ([]string, error) { return builder.Discover(dir) }
@@ -92,6 +93,7 @@ func RenderAll(themesDir string, cfg *config.TemplatesConfig, filter map[string]
 		return nil, err
 	}
 	result := &PreviewResult{Rendered: map[string]map[string]map[string]string{}, Registry: config.Registry(cfg), Params: map[string]map[string]string{}, Languages: s.Languages(), Upstream: s.Lock.Tag, Fallback: missing, Warnings: map[string]map[string][]string{}}
+	result.LanguageNames = languageNames(result.Languages)
 	for id, t := range cfg.Templates {
 		result.Params[id] = config.FlattenParams(t.Params)
 	}
@@ -236,6 +238,7 @@ func WriteRenderedJS(result *PreviewResult, output string) error {
 		return err
 	}
 	manifest := map[string]any{"schema": 1, "upstream": result.Upstream, "languages": result.Languages, "themes": result.Themes, "registry": result.Registry, "params": result.Params, "fallback": result.Fallback, "warnings": result.Warnings}
+	manifest["language_names"] = result.LanguageNames
 	manifest["logo"] = "data:image/png;base64," + base64.StdEncoding.EncodeToString(result.Logo)
 	manifest["upstream_commit"] = result.Commit
 	data, err := json.Marshal(manifest)
@@ -267,10 +270,8 @@ func PrintDetailedSummary(result *PreviewResult, _ string, _ *config.TemplatesCo
 				logging.Warn("Upstream", "%s", strings.TrimPrefix(warning, "[UPSTREAM-WARN] "))
 			}
 		}
-		if keys := result.Fallback[lang]; len(keys) > 0 {
-			logging.Warn("Locale", "%s -> en-US: %s", lang, strings.Join(keys, ", "))
-		}
 	}
+	logging.WarnMissingTranslations(result.Fallback)
 }
 
 func markSafeHTML(data map[string]any) {