diff --git a/py/services/cache_entry_validator.py b/py/services/cache_entry_validator.py
index 08148258..c4848856 100644
--- a/py/services/cache_entry_validator.py
+++ b/py/services/cache_entry_validator.py
@@ -125,16 +125,20 @@ class CacheEntryValidator:
             )
 
         # Special validation: sha256 must not be empty for required field
+        # BUT allow empty sha256 when hash_status is pending (lazy hash calculation)
         sha256 = working_entry.get('sha256', '')
+        hash_status = working_entry.get('hash_status', 'completed')
         if not sha256 or (isinstance(sha256, str) and not sha256.strip()):
-            errors.append("Required field 'sha256' is empty")
-            # Cannot repair empty sha256 - entry is invalid
-            return ValidationResult(
-                is_valid=False,
-                repaired=repaired,
-                errors=errors,
-                entry=working_entry if auto_repair else None
-            )
+            # Allow empty sha256 for lazy hash calculation (checkpoints)
+            if hash_status != 'pending':
+                errors.append("Required field 'sha256' is empty")
+                # Cannot repair empty sha256 - entry is invalid
+                return ValidationResult(
+                    is_valid=False,
+                    repaired=repaired,
+                    errors=errors,
+                    entry=working_entry if auto_repair else None
+                )
 
         # Normalize sha256 to lowercase if needed
         if isinstance(sha256, str):
diff --git a/py/services/use_cases/bulk_metadata_refresh_use_case.py b/py/services/use_cases/bulk_metadata_refresh_use_case.py
index 51f1fb28..13b5d6b7 100644
--- a/py/services/use_cases/bulk_metadata_refresh_use_case.py
+++ b/py/services/use_cases/bulk_metadata_refresh_use_case.py
@@ -47,8 +47,7 @@ class BulkMetadataRefreshUseCase:
         to_process: Sequence[Dict[str, Any]] = [
             model
             for model in cache.raw_data
-            if model.get("sha256")
-            and not model.get("skip_metadata_refresh", False)
+            if not model.get("skip_metadata_refresh", False)
             and not self._is_in_skip_path(model.get("folder", ""), skip_paths)
             and (not model.get("civitai") or not model["civitai"].get("id"))
             and not (
@@ -85,6 +84,36 @@ class BulkMetadataRefreshUseCase:
                 return {"success": False, "message": "Operation cancelled", "processed": processed, "updated": success, "total": total_models}
             try:
                 original_name = model.get("model_name")
+
+                # Handle lazy hash calculation for models with pending hash status
+                sha256 = model.get("sha256", "")
+                hash_status = model.get("hash_status", "completed")
+                file_path = model.get("file_path")
+
+                if not sha256 and hash_status == "pending" and file_path:
+                    self._logger.info(f"Calculating pending hash for {file_path}")
+                    # Check if scanner has calculate_hash_for_model method (CheckpointScanner)
+                    calculate_hash_method = getattr(self._service.scanner, "calculate_hash_for_model", None)
+                    if calculate_hash_method:
+                        sha256 = await calculate_hash_method(file_path)
+                        if sha256:
+                            model["sha256"] = sha256
+                            model["hash_status"] = "completed"
+                        else:
+                            self._logger.error(f"Failed to calculate hash for {file_path}")
+                            processed += 1
+                            continue
+                    else:
+                        self._logger.warning(f"Scanner does not support lazy hash calculation for {file_path}")
+                        processed += 1
+                        continue
+
+                # Skip models without valid hash
+                if not model.get("sha256"):
+                    self._logger.warning(f"Skipping model without hash: {file_path}")
+                    processed += 1
+                    continue
+
                 await MetadataManager.hydrate_model_data(model)
                 result, _ = await self._metadata_sync.fetch_and_update_model(
                     sha256=model["sha256"],
diff --git a/tests/services/test_cache_entry_validator.py b/tests/services/test_cache_entry_validator.py
index 0a36b606..58fc75ff 100644
--- a/tests/services/test_cache_entry_validator.py
+++ b/tests/services/test_cache_entry_validator.py
@@ -73,6 +73,46 @@ class TestCacheEntryValidator:
         assert result.repaired is False
         assert any('sha256' in error for error in result.errors)
 
+    def test_validate_empty_sha256_allowed_when_hash_status_pending(self):
+        """Test validation passes when sha256 is empty but hash_status is pending (lazy hash)"""
+        entry = {
+            'file_path': '/models/test.safetensors',
+            'sha256': '',  # Empty string
+            'hash_status': 'pending',  # Lazy hash calculation
+        }
+
+        result = CacheEntryValidator.validate(entry, auto_repair=False)
+
+        assert result.is_valid is True
+        assert result.entry['sha256'] == ''
+        assert result.entry['hash_status'] == 'pending'
+
+    def test_validate_empty_sha256_fails_when_hash_status_not_pending(self):
+        """Test validation fails when sha256 is empty and hash_status is not pending"""
+        entry = {
+            'file_path': '/models/test.safetensors',
+            'sha256': '',  # Empty string
+            'hash_status': 'completed',  # Not pending
+        }
+
+        result = CacheEntryValidator.validate(entry, auto_repair=False)
+
+        assert result.is_valid is False
+        assert any('sha256' in error for error in result.errors)
+
+    def test_validate_empty_sha256_fails_when_hash_status_missing(self):
+        """Test validation fails when sha256 is empty and hash_status is missing"""
+        entry = {
+            'file_path': '/models/test.safetensors',
+            'sha256': '',  # Empty string
+            # hash_status missing (defaults to 'completed')
+        }
+
+        result = CacheEntryValidator.validate(entry, auto_repair=False)
+
+        assert result.is_valid is False
+        assert any('sha256' in error for error in result.errors)
+
     def test_validate_empty_required_field_file_path(self):
         """Test validation fails when file_path is empty string"""
         entry = {
diff --git a/tests/services/use_cases/test_bulk_metadata_refresh_use_case.py b/tests/services/use_cases/test_bulk_metadata_refresh_use_case.py
new file mode 100644
index 00000000..b0feae76
--- /dev/null
+++ b/tests/services/use_cases/test_bulk_metadata_refresh_use_case.py
@@ -0,0 +1,404 @@
+"""Tests for BulkMetadataRefreshUseCase."""
+
+from __future__ import annotations
+
+import pytest
+from types import SimpleNamespace
+from typing import Any, Dict
+from unittest.mock import AsyncMock, MagicMock, patch
+
+from py.services.use_cases.bulk_metadata_refresh_use_case import (
+    BulkMetadataRefreshUseCase,
+    MetadataRefreshProgressReporter,
+)
+from py.utils import metadata_manager
+
+
+class MockProgressReporter:
+    """Mock progress reporter for testing."""
+
+    def __init__(self):
+        self.progress_calls = []
+
+    async def on_progress(self, payload: Dict[str, Any]) -> None:
+        self.progress_calls.append(payload)
+
+
+@pytest.fixture
+def mock_service():
+    """Create a mock service with scanner."""
+    scanner = MagicMock()
+    scanner.get_cached_data = AsyncMock()
+    scanner.reset_cancellation = MagicMock()
+    scanner.is_cancelled = MagicMock(return_value=False)
+    scanner.update_single_model_cache = AsyncMock(return_value=True)
+    scanner.calculate_hash_for_model = AsyncMock(return_value="calculated_hash_123")
+
+    service = MagicMock()
+    service.scanner = scanner
+    service.model_type = "checkpoint"
+
+    return service
+
+
+@pytest.fixture
+def mock_metadata_sync():
+    """Create a mock metadata sync service."""
+    sync = MagicMock()
+    sync.fetch_and_update_model = AsyncMock(return_value=(True, None))
+    return sync
+
+
+@pytest.fixture
+def mock_settings():
+    """Create mock settings service."""
+    settings = MagicMock()
+    settings.get = MagicMock(return_value=False)
+    return settings
+
+
+@pytest.fixture
+def use_case(mock_service, mock_metadata_sync, mock_settings):
+    """Create a BulkMetadataRefreshUseCase instance."""
+    return BulkMetadataRefreshUseCase(
+        service=mock_service,
+        metadata_sync=mock_metadata_sync,
+        settings_service=mock_settings,
+    )
+
+
+@pytest.mark.asyncio
+@patch.object(metadata_manager.MetadataManager, "hydrate_model_data")
+async def test_pending_hash_calculated_on_demand(mock_hydrate, use_case, mock_service, mock_metadata_sync):
+    """Test that models with pending hash status get their hash calculated on demand."""
+    mock_hydrate.return_value = None
+    
+    # Setup cache with a model that has pending hash
+    pending_model = {
+        "file_path": "/extra_ckpt/model.safetensors",
+        "sha256": "",  # Empty hash
+        "hash_status": "pending",
+        "model_name": "Test Model",
+        "folder": "extra_ckpt",
+        "civitai": {},
+        "from_civitai": False,
+        "civitai_deleted": False,
+    }
+
+    cache = SimpleNamespace(raw_data=[pending_model], resort=AsyncMock())
+    mock_service.scanner.get_cached_data.return_value = cache
+
+    # Execute
+    result = await use_case.execute()
+
+    # Verify hash was calculated
+    mock_service.scanner.calculate_hash_for_model.assert_called_once_with(
+        "/extra_ckpt/model.safetensors"
+    )
+
+    # Verify model hash was updated
+    assert pending_model["sha256"] == "calculated_hash_123"
+    assert pending_model["hash_status"] == "completed"
+
+    # Verify metadata sync was called with the calculated hash
+    mock_metadata_sync.fetch_and_update_model.assert_called_once()
+    call_args = mock_metadata_sync.fetch_and_update_model.call_args[1]
+    assert call_args["sha256"] == "calculated_hash_123"
+
+    assert result["success"] is True
+
+
+@pytest.mark.asyncio
+@patch.object(metadata_manager.MetadataManager, "hydrate_model_data")
+async def test_skip_model_when_hash_calculation_fails(mock_hydrate, use_case, mock_service, mock_metadata_sync):
+    """Test that models are skipped when hash calculation fails."""
+    mock_hydrate.return_value = None
+    
+    # Setup model with pending hash
+    pending_model = {
+        "file_path": "/extra_ckpt/model.safetensors",
+        "sha256": "",
+        "hash_status": "pending",
+        "model_name": "Test Model",
+        "civitai": {},
+        "from_civitai": False,
+        "civitai_deleted": False,
+    }
+
+    # Make hash calculation fail
+    mock_service.scanner.calculate_hash_for_model.return_value = None
+
+    cache = SimpleNamespace(raw_data=[pending_model], resort=AsyncMock())
+    mock_service.scanner.get_cached_data.return_value = cache
+
+    # Execute
+    result = await use_case.execute()
+
+    # Verify hash was attempted
+    mock_service.scanner.calculate_hash_for_model.assert_called_once()
+
+    # Verify metadata sync was NOT called (model skipped)
+    mock_metadata_sync.fetch_and_update_model.assert_not_called()
+
+    # Verify result shows processed but no success
+    assert result["success"] is True
+    assert result["processed"] == 1
+    assert result["updated"] == 0
+
+
+@pytest.mark.asyncio
+async def test_skip_model_when_scanner_does_not_support_lazy_hash(
+    use_case, mock_service, mock_metadata_sync
+):
+    """Test that models are skipped when scanner doesn't support lazy hash calculation."""
+    # Setup model with pending hash
+    pending_model = {
+        "file_path": "/models/model.safetensors",
+        "sha256": "",
+        "hash_status": "pending",
+        "model_name": "Test Model",
+        "civitai": {},
+        "from_civitai": False,
+        "civitai_deleted": False,
+    }
+
+    # Remove calculate_hash_for_model method (simulating LoRA scanner)
+    del mock_service.scanner.calculate_hash_for_model
+
+    cache = SimpleNamespace(raw_data=[pending_model], resort=AsyncMock())
+    mock_service.scanner.get_cached_data.return_value = cache
+
+    # Execute
+    result = await use_case.execute()
+
+    # Verify metadata sync was NOT called
+    mock_metadata_sync.fetch_and_update_model.assert_not_called()
+
+    assert result["success"] is True
+    assert result["processed"] == 1
+    assert result["updated"] == 0
+
+
+@pytest.mark.asyncio
+@patch.object(metadata_manager.MetadataManager, "hydrate_model_data")
+async def test_normal_model_with_existing_hash_not_affected(mock_hydrate, use_case, mock_service, mock_metadata_sync):
+    """Test that models with existing hash work normally."""
+    mock_hydrate.return_value = None
+    
+    # Setup model with existing hash
+    existing_model = {
+        "file_path": "/models/model.safetensors",
+        "sha256": "existing_hash_abc",
+        "hash_status": "completed",
+        "model_name": "Test Model",
+        "civitai": {},
+        "from_civitai": False,
+        "civitai_deleted": False,
+    }
+
+    cache = SimpleNamespace(raw_data=[existing_model], resort=AsyncMock())
+    mock_service.scanner.get_cached_data.return_value = cache
+
+    # Execute
+    result = await use_case.execute()
+
+    # Verify hash calculation was NOT called
+    assert not mock_service.scanner.calculate_hash_for_model.called
+
+    # Verify metadata sync was called with existing hash
+    mock_metadata_sync.fetch_and_update_model.assert_called_once()
+    call_args = mock_metadata_sync.fetch_and_update_model.call_args[1]
+    assert call_args["sha256"] == "existing_hash_abc"
+
+    assert result["success"] is True
+    assert result["updated"] == 1
+
+
+@pytest.mark.asyncio
+@patch.object(metadata_manager.MetadataManager, "hydrate_model_data")
+async def test_mixed_models_some_pending_some_existing(mock_hydrate, use_case, mock_service, mock_metadata_sync):
+    """Test handling of mixed models: some with pending hash, some with existing hash."""
+    mock_hydrate.return_value = None
+    
+    pending_model = {
+        "file_path": "/extra_ckpt/pending_model.safetensors",
+        "sha256": "",
+        "hash_status": "pending",
+        "model_name": "Pending Model",
+        "civitai": {},
+        "from_civitai": False,
+        "civitai_deleted": False,
+    }
+
+    existing_model = {
+        "file_path": "/models/existing_model.safetensors",
+        "sha256": "existing_hash_xyz",
+        "hash_status": "completed",
+        "model_name": "Existing Model",
+        "civitai": {},
+        "from_civitai": False,
+        "civitai_deleted": False,
+    }
+
+    cache = SimpleNamespace(raw_data=[pending_model, existing_model], resort=AsyncMock())
+    mock_service.scanner.get_cached_data.return_value = cache
+
+    # Execute
+    result = await use_case.execute()
+
+    # Verify hash was calculated only for pending model
+    mock_service.scanner.calculate_hash_for_model.assert_called_once_with(
+        "/extra_ckpt/pending_model.safetensors"
+    )
+
+    # Verify metadata sync was called for both
+    assert mock_metadata_sync.fetch_and_update_model.call_count == 2
+
+    assert result["success"] is True
+    assert result["processed"] == 2
+
+
+@pytest.mark.asyncio
+@patch.object(metadata_manager.MetadataManager, "hydrate_model_data")
+async def test_progress_callback_receives_updates(mock_hydrate, use_case, mock_service):
+    """Test that progress callback receives correct updates."""
+    mock_hydrate.return_value = None
+    
+    model = {
+        "file_path": "/models/model.safetensors",
+        "sha256": "hash123",
+        "model_name": "Test Model",
+        "civitai": {},
+        "from_civitai": False,
+        "civitai_deleted": False,
+    }
+
+    cache = SimpleNamespace(raw_data=[model], resort=AsyncMock())
+    mock_service.scanner.get_cached_data.return_value = cache
+
+    reporter = MockProgressReporter()
+
+    # Execute
+    await use_case.execute(progress_callback=reporter)
+
+    # Verify progress was reported
+    assert len(reporter.progress_calls) >= 2
+
+    # Check started status
+    started_calls = [c for c in reporter.progress_calls if c["status"] == "started"]
+    assert len(started_calls) == 1
+
+    # Check completed status
+    completed_calls = [c for c in reporter.progress_calls if c["status"] == "completed"]
+    assert len(completed_calls) == 1
+    assert completed_calls[0]["processed"] == 1
+    assert completed_calls[0]["success"] == 1
+
+
+@pytest.mark.asyncio
+@patch.object(metadata_manager.MetadataManager, "hydrate_model_data")
+async def test_respects_skip_metadata_refresh_flag(mock_hydrate, use_case, mock_service, mock_metadata_sync):
+    """Test that models with skip_metadata_refresh=True are skipped."""
+    mock_hydrate.return_value = None
+    
+    skip_model = {
+        "file_path": "/models/skip_model.safetensors",
+        "sha256": "hash123",
+        "model_name": "Skip Model",
+        "skip_metadata_refresh": True,
+        "civitai": {},
+    }
+
+    normal_model = {
+        "file_path": "/models/normal_model.safetensors",
+        "sha256": "hash456",
+        "model_name": "Normal Model",
+        "civitai": {},
+        "from_civitai": False,
+        "civitai_deleted": False,
+    }
+
+    cache = SimpleNamespace(raw_data=[skip_model, normal_model], resort=AsyncMock())
+    mock_service.scanner.get_cached_data.return_value = cache
+
+    # Execute
+    result = await use_case.execute()
+
+    # Verify only normal model was processed
+    assert mock_metadata_sync.fetch_and_update_model.call_count == 1
+    call_args = mock_metadata_sync.fetch_and_update_model.call_args[1]
+    assert call_args["file_path"] == "/models/normal_model.safetensors"
+
+    assert result["processed"] == 1
+
+
+@pytest.mark.asyncio
+@patch.object(metadata_manager.MetadataManager, "hydrate_model_data")
+async def test_respects_skip_paths(mock_hydrate, use_case, mock_service, mock_metadata_sync):
+    """Test that models in skip paths are excluded."""
+    mock_hydrate.return_value = None
+    
+    # Setup settings to skip certain paths
+    use_case._settings.get = MagicMock(side_effect=lambda key, default=None: {
+        "enable_metadata_archive_db": False,
+        "metadata_refresh_skip_paths": ["skip_folder"],
+    }.get(key, default))
+
+    skip_path_model = {
+        "file_path": "/models/skip_folder/model.safetensors",
+        "sha256": "hash123",
+        "model_name": "Skip Path Model",
+        "folder": "skip_folder",
+        "civitai": {},
+        "from_civitai": False,
+        "civitai_deleted": False,
+    }
+
+    normal_model = {
+        "file_path": "/models/normal/model.safetensors",
+        "sha256": "hash456",
+        "model_name": "Normal Model",
+        "folder": "normal",
+        "civitai": {},
+        "from_civitai": False,
+        "civitai_deleted": False,
+    }
+
+    cache = SimpleNamespace(raw_data=[skip_path_model, normal_model], resort=AsyncMock())
+    mock_service.scanner.get_cached_data.return_value = cache
+
+    # Execute
+    result = await use_case.execute()
+
+    # Verify only normal model was processed
+    assert mock_metadata_sync.fetch_and_update_model.call_count == 1
+    call_args = mock_metadata_sync.fetch_and_update_model.call_args[1]
+    assert "normal" in call_args["file_path"]
+
+    assert result["processed"] == 1
+
+
+@pytest.mark.asyncio
+async def test_model_without_hash_skipped(use_case, mock_service, mock_metadata_sync):
+    """Test that models without hash (and not pending) are skipped."""
+    no_hash_model = {
+        "file_path": "/models/no_hash_model.safetensors",
+        "sha256": "",  # Empty but NOT pending
+        "hash_status": "completed",  # Not pending
+        "model_name": "No Hash Model",
+        "civitai": {},
+        "from_civitai": False,
+        "civitai_deleted": False,
+    }
+
+    cache = SimpleNamespace(raw_data=[no_hash_model], resort=AsyncMock())
+    mock_service.scanner.get_cached_data.return_value = cache
+
+    # Execute
+    result = await use_case.execute()
+
+    # Verify metadata sync was NOT called
+    mock_metadata_sync.fetch_and_update_model.assert_not_called()
+
+    assert result["processed"] == 1
+    assert result["updated"] == 0