feat(metadata): enhance primary sampler detection and workflow tracing

- Add support for `basic_pipe` nodes in metadata processor to handle pipeline nodes like FromBasicPipe
- Optimize `find_primary_checkpoint` by accepting optional `primary_sampler_id` to avoid redundant calculations
- Update `get_workflow_trace` to pass known primary sampler ID for improved efficiency

tests/metadata_collector/test_pipe_tracer.py

@@ -0,0 +1,98 @@
+
+import pytest
+from types import SimpleNamespace
+from py.metadata_collector.metadata_processor import MetadataProcessor
+from py.metadata_collector.constants import MODELS, SAMPLING, IS_SAMPLER
+
+class TestPipeTracer:
+    
+    @pytest.fixture
+    def pipe_workflow_metadata(self):
+        """
+        Creates a mock metadata structure matching the one provided in refs/tmp.
+        Structure:
+        Load Checkpoint(28) -> Lora Loader(52) -> ToBasicPipe(69) -> FromBasicPipe(71) -> KSampler(32)
+        """
+        
+        original_prompt = {
+            '28': {
+                'inputs': {'ckpt_name': 'Illustrious\\bananaSplitzXL_vee5PointOh.safetensors'}, 
+                'class_type': 'CheckpointLoaderSimple'
+            },
+            '52': {
+                'inputs': {
+                    'model': ['28', 0],
+                    'clip': ['28', 1]
+                }, 
+                'class_type': 'Lora Loader (LoraManager)'
+            },
+            '69': {
+                'inputs': {
+                    'model': ['52', 0], 
+                    'clip': ['52', 1], 
+                    'vae': ['28', 2], 
+                    'positive': ['75', 0], 
+                    'negative': ['30', 0]
+                }, 
+                'class_type': 'ToBasicPipe'
+            },
+            '71': {
+                'inputs': {'basic_pipe': ['69', 0]}, 
+                'class_type': 'FromBasicPipe'
+            },
+            '32': {
+                'inputs': {
+                    'seed': 131755205602911, 
+                    'steps': 5, 
+                    'cfg': 8.0, 
+                    'sampler_name': 'euler_ancestral', 
+                    'scheduler': 'karras', 
+                    'denoise': 1.0, 
+                    'model': ['71', 0], 
+                    'positive': ['71', 3], 
+                    'negative': ['71', 4], 
+                    'latent_image': ['76', 0]
+                }, 
+                'class_type': 'KSampler'
+            },
+            '75': {'inputs': {'text': 'positive', 'clip': ['52', 1]}, 'class_type': 'CLIPTextEncode'},
+            '30': {'inputs': {'text': 'negative', 'clip': ['52', 1]}, 'class_type': 'CLIPTextEncode'},
+            '76': {'inputs': {'width': 832, 'height': 1216, 'batch_size': 1}, 'class_type': 'EmptyLatentImage'}
+        }
+        
+        metadata = {
+            "current_prompt": SimpleNamespace(original_prompt=original_prompt),
+            MODELS: {
+                "28": {
+                    "type": "checkpoint",
+                    "name": "bananaSplitzXL_vee5PointOh.safetensors"
+                }
+            },
+            SAMPLING: {
+                "32": {
+                    IS_SAMPLER: True,
+                    "parameters": {
+                        "sampler_name": "euler_ancestral",
+                        "scheduler": "karras"
+                    }
+                }
+            }
+        }
+        
+        return metadata
+
+    def test_trace_model_path_through_pipe(self, pipe_workflow_metadata):
+        """Verify trace_model_path can follow: KSampler -> FromBasicPipe -> ToBasicPipe -> Lora -> Checkpoint."""
+        prompt = pipe_workflow_metadata["current_prompt"]
+        
+        # Start trace from KSampler (32)
+        ckpt_id = MetadataProcessor.trace_model_path(pipe_workflow_metadata, prompt, "32")
+        
+        assert ckpt_id == "28"
+
+    def test_find_primary_checkpoint_with_pipe(self, pipe_workflow_metadata):
+        """Verify find_primary_checkpoint returns the correct name even with pipe nodes."""
+        # Providing sampler_id to test the optimization as well
+        name = MetadataProcessor.find_primary_checkpoint(pipe_workflow_metadata, primary_sampler_id="32")
+        
+        assert name == "bananaSplitzXL_vee5PointOh.safetensors"