feat: expose provider button defaults in admin settings manifest

backend/bot/app/web/admin_settings_manifest.py

@@ -353,7 +353,15 @@ def coerce_value(field: SettingField, raw: Any) -> Any:
 
 
 def manifest_payload() -> List[dict]:
-    """Serialize the manifest for the admin UI."""
+    """Serialize the manifest for the admin UI.
+
+    For provider presentation fields we resolve the SPEC-declared default
+    (e.g. the button text the bot would use if the admin leaves the override
+    blank) and expose it as ``default``; ``placeholder`` falls back to the
+    same value so existing UIs that only read ``placeholder`` also show the
+    hint inside the empty input.
+    """
+    from bot.payment_providers import find_manifest_owner, manifest_field_default
 
     sections_order = {
         "general": 1,
@@ -369,6 +377,17 @@ def manifest_payload() -> List[dict]:
     for field in aggregated_manifest():
         auto_label_i18n_key = f"settings_field_{field.key.lower()}_label"
         auto_description_i18n_key = f"settings_field_{field.key.lower()}_description"
+
+        default_value: Optional[str] = None
+        owner = find_manifest_owner(field.key)
+        if owner is not None:
+            spec, manifest_field = owner
+            default_value = manifest_field_default(spec, manifest_field)
+
+        placeholder = field.placeholder
+        if not placeholder and default_value:
+            placeholder = default_value
+
         item = {
             "key": field.key,
             "type": field.type,
@@ -380,10 +399,12 @@ def manifest_payload() -> List[dict]:
             "i18n_label_key": field.i18n_label_key or auto_label_i18n_key,
             "i18n_description_key": field.i18n_description_key
             or (auto_description_i18n_key if field.description else None),
-            "placeholder": field.placeholder,
+            "placeholder": placeholder,
             "optional": field.optional,
             "secret": field.secret,
         }
+        if default_value is not None:
+            item["default"] = default_value
         if field.choices:
             item["choices"] = [{"value": v, "label": lbl} for v, lbl in field.choices]
         items.append(item)

backend/bot/payment_providers/__init__.py

@@ -18,6 +18,7 @@ from .registry import (
     get_spec_presentation,
     iter_provider_manifest_fields,
     iter_provider_specs,
+    manifest_field_default,
     iter_service_keys,
     iter_unique_provider_routers,
     pending_statuses,
@@ -45,6 +46,7 @@ __all__ = [
     "get_spec_presentation",
     "iter_provider_manifest_fields",
     "iter_provider_specs",
+    "manifest_field_default",
     "iter_service_keys",
     "iter_unique_provider_routers",
     "pending_statuses",

backend/bot/payment_providers/registry.py

@@ -324,3 +324,38 @@ def find_manifest_owner(key: str) -> Optional[tuple[PaymentProviderSpec, Provide
         if field.key == key:
             return spec, field
     return None
+
+
+def manifest_field_default(
+    spec: PaymentProviderSpec,
+    manifest_field: ProviderManifestField,
+) -> Optional[str]:
+    """Resolve the SPEC-declared default for a presentation manifest field.
+
+    Used by the admin UI to render a placeholder/hint that shows users what
+    button text or icon the bot falls back to when they leave the override
+    blank. Returns None for non-presentation fields or attributes we don't
+    have a mapping for (admin shouldn't render a misleading hint).
+    """
+    if manifest_field.target != "presentation":
+        return None
+    attr = manifest_field.attr or manifest_field.key
+    if attr == "WEBAPP_LABEL_RU":
+        return (
+            _localized_default(spec.webapp_labels, "ru", spec.webapp_label)
+            or spec.label
+        )
+    if attr == "WEBAPP_LABEL_EN":
+        return (
+            _localized_default(spec.webapp_labels, "en", spec.webapp_label)
+            or spec.label
+        )
+    if attr == "WEBAPP_ICON":
+        return spec.webapp_icon
+    if attr == "TELEGRAM_LABEL_RU":
+        return _localized_default(spec.telegram_labels, "ru", None) or spec.label
+    if attr == "TELEGRAM_LABEL_EN":
+        return _localized_default(spec.telegram_labels, "en", None) or spec.label
+    if attr == "TELEGRAM_EMOJI":
+        return spec.default_telegram_emoji
+    return None