feat(14.2.1-05): hydrate ML create/GET/save through TranslatedExact

Form schema meta lists enabled locales, Show/save expand mltext maps
without D-11 fallback, and the SPA seeds and adopt-merges every locale.

Co-authored-by: Cursor <cursoragent@cursor.com>

modules/cabana/field_ml.go

@@ -12,11 +12,13 @@ const (
 	mlMarkdownFieldType = "mlmarkdown"
 )
 
-// TranslationWriter persists non-default locale values during a cabana save.
-// The interface lives in the framework so cabana never imports a plugin; a
-// host publishes an adapter at Boot. There is no standalone translate-write
+// TranslationWriter persists non-default locale values during a cabana save
+// and reads exact stored translations for Show/save hydration. The interface
+// lives in the framework so cabana never imports a plugin; a host publishes
+// an adapter at Boot. There is no standalone translate-read or translate-write
 // HTTP endpoint: writes run only inside a permissioned, scoped host save
-// transaction after the host row has a primary key.
+// transaction after the host row has a primary key, and reads run on the
+// same adapter after projectFullRecord.
 type TranslationWriter interface {
 	// DefaultLocale is the host-column locale.
 	DefaultLocale(ctx context.Context, tx *gorm.DB) (string, error)
@@ -25,6 +27,11 @@ type TranslationWriter interface {
 	// WriteTranslated stores field in locale for model. locale is never the
 	// default; cabana already filled the host scalar.
 	WriteTranslated(ctx context.Context, tx *gorm.DB, model any, field, locale, value string) error
+	// TranslatedExact returns the stored value for field in locale. ok is
+	// false when the non-default key is missing. It must not apply D-11
+	// fallback: empty admin values stay empty. The default locale still
+	// reads the host column.
+	TranslatedExact(ctx context.Context, tx *gorm.DB, model any, field, locale string) (string, bool, error)
 }
 
 // mlValue is one multilingual field lifted from a save body.
@@ -158,3 +165,68 @@ func applyMLTranslations(ctx context.Context, tx *gorm.DB, writer TranslationWri
 	}
 	return nil
 }
+
+// hydrateMLRecord replaces host scalars of declared mltext/mlmarkdown fields
+// in a Show/save RecordResult.Data map with a locale→text map for every
+// enabled code. The default locale is the projected host column; other codes
+// come from TranslatedExact; a missing non-default code is an empty string,
+// never D-11 fallback. It is a no-op when writer is nil and is not used from
+// list row projection.
+func hydrateMLRecord(ctx context.Context, tx *gorm.DB, cc *CompiledController, writer TranslationWriter, model any, data map[string]any, op string) error {
+	if writer == nil || cc == nil || cc.Form == nil || data == nil {
+		return nil
+	}
+	var names []string
+	for _, field := range cc.Form.Fields {
+		if !mlFieldType(field.Type) || !contextAllows(cc, field.Name, op) {
+			continue
+		}
+		names = append(names, field.Name)
+	}
+	if len(names) == 0 {
+		return nil
+	}
+	defaultLocale, err := writer.DefaultLocale(ctx, tx)
+	if err != nil || defaultLocale == "" {
+		return fmt.Errorf("cabana: default locale: %w", err)
+	}
+	codes, err := writer.EnabledLocales(ctx, tx)
+	if err != nil {
+		return fmt.Errorf("cabana: enabled locales: %w", err)
+	}
+	for _, name := range names {
+		host := hostScalarString(data[name])
+		out := make(map[string]string, len(codes))
+		for _, code := range codes {
+			if code == defaultLocale {
+				out[code] = host
+				continue
+			}
+			text, ok, err := writer.TranslatedExact(ctx, tx, model, name, code)
+			if err != nil {
+				return err
+			}
+			if !ok {
+				out[code] = ""
+				continue
+			}
+			out[code] = text
+		}
+		data[name] = out
+	}
+	return nil
+}
+
+func hostScalarString(v any) string {
+	if v == nil {
+		return ""
+	}
+	switch t := v.(type) {
+	case string:
+		return t
+	case []byte:
+		return string(t)
+	default:
+		return fmt.Sprint(t)
+	}
+}