feat: implement same_base update strategy for model annotations

Add support for configurable update flag strategy with new "same_base" mode that considers base model versions when determining update availability. The strategy is controlled by the "update_flag_strategy" setting.

When strategy is set to "same_base":
- Uses get_records_bulk instead of has_updates_bulk
- Compares model versions against highest local versions per base model
- Provides more granular update detection based on base model relationships

Fallback to existing bulk or individual update checks when:
- Strategy is not "same_base"
- Bulk operations fail
- Records are unavailable

This enables more precise update flagging for models sharing common bases.

py/services/base_model_service.py

@@ -267,20 +267,49 @@ class BaseModelService(ABC):
         if not ordered_ids:
             return annotated
 
+        strategy_value = self.settings.get("update_flag_strategy")
+        if isinstance(strategy_value, str) and strategy_value.strip():
+            strategy = strategy_value.strip().lower()
+        else:
+            strategy = "any"
+        same_base_mode = strategy == "same_base"
+
+        records = None
         resolved: Optional[Dict[int, bool]] = None
-        bulk_method = getattr(self.update_service, "has_updates_bulk", None)
-        if callable(bulk_method):
-            try:
-                resolved = await bulk_method(self.model_type, ordered_ids)
-            except Exception as exc:
-                logger.error(
-                    "Failed to resolve update status in bulk for %s models (%s): %s",
-                    self.model_type,
-                    ordered_ids,
-                    exc,
-                    exc_info=True,
-                )
-                resolved = None
+        if same_base_mode:
+            record_method = getattr(self.update_service, "get_records_bulk", None)
+            if callable(record_method):
+                try:
+                    records = await record_method(self.model_type, ordered_ids)
+                    resolved = {
+                        model_id: record.has_update()
+                        for model_id, record in records.items()
+                    }
+                except Exception as exc:
+                    logger.error(
+                        "Failed to resolve update records in bulk for %s models (%s): %s",
+                        self.model_type,
+                        ordered_ids,
+                        exc,
+                        exc_info=True,
+                    )
+                    records = None
+                    resolved = None
+
+        if resolved is None:
+            bulk_method = getattr(self.update_service, "has_updates_bulk", None)
+            if callable(bulk_method):
+                try:
+                    resolved = await bulk_method(self.model_type, ordered_ids)
+                except Exception as exc:
+                    logger.error(
+                        "Failed to resolve update status in bulk for %s models (%s): %s",
+                        self.model_type,
+                        ordered_ids,
+                        exc,
+                        exc_info=True,
+                    )
+                    resolved = None
 
         if resolved is None:
             tasks = [
@@ -301,8 +330,24 @@ class BaseModelService(ABC):
                 resolved[model_id] = bool(result)
 
         for model_id, items_for_id in id_to_items.items():
-            flag = bool(resolved.get(model_id, False))
+            default_flag = bool(resolved.get(model_id, False)) if resolved else False
+            record = records.get(model_id) if records else None
+            base_highest_versions = (
+                self._build_highest_local_versions_by_base(record) if same_base_mode and record else {}
+            )
             for item in items_for_id:
+                if same_base_mode and record is not None:
+                    base_model = self._extract_base_model(item)
+                    normalized_base = self._normalize_base_model_name(base_model)
+                    threshold_version = base_highest_versions.get(normalized_base) if normalized_base else None
+                    if threshold_version is None:
+                        threshold_version = self._extract_version_id(item)
+                    flag = record.has_update_for_base(
+                        threshold_version,
+                        base_model,
+                    )
+                else:
+                    flag = default_flag
                 item['update_available'] = flag
 
         return annotated
@@ -319,7 +364,71 @@ class BaseModelService(ABC):
             return int(value)
         except (TypeError, ValueError):
             return None
-    
+
+    @staticmethod
+    def _extract_version_id(item: Dict) -> Optional[int]:
+        civitai = item.get('civitai') if isinstance(item, dict) else None
+        if not isinstance(civitai, dict):
+            return None
+        value = civitai.get('id')
+        if value is None:
+            return None
+        try:
+            return int(value)
+        except (TypeError, ValueError):
+            return None
+
+    @staticmethod
+    def _extract_base_model(item: Dict) -> Optional[str]:
+        value = item.get('base_model')
+        if value is None:
+            return None
+        if isinstance(value, str):
+            candidate = value.strip()
+        else:
+            try:
+                candidate = str(value).strip()
+            except Exception:
+                return None
+        return candidate if candidate else None
+
+    @staticmethod
+    def _normalize_base_model_name(value: Optional[str]) -> Optional[str]:
+        """Return a lowercased, trimmed base model name for comparison."""
+
+        if value is None:
+            return None
+        if isinstance(value, str):
+            candidate = value.strip()
+        else:
+            try:
+                candidate = str(value).strip()
+            except Exception:
+                return None
+        return candidate.lower() if candidate else None
+
+    def _build_highest_local_versions_by_base(self, record) -> Dict[str, int]:
+        """Return the highest local version id known for each normalized base model."""
+
+        if record is None:
+            return {}
+
+        highest_by_base: Dict[str, int] = {}
+        for version in getattr(record, "versions", []):
+            if not getattr(version, "is_in_library", False):
+                continue
+            normalized_base = self._normalize_base_model_name(getattr(version, "base_model", None))
+            if normalized_base is None:
+                continue
+            version_id = getattr(version, "version_id", None)
+            if version_id is None:
+                continue
+            current_max = highest_by_base.get(normalized_base)
+            if current_max is None or version_id > current_max:
+                highest_by_base[normalized_base] = version_id
+
+        return highest_by_base
+
     def _paginate(self, data: List[Dict], page: int, page_size: int) -> Dict:
         """Apply pagination to filtered data"""
         total_items = len(data)