feat(cwb): preserve secondary-only layers

- build generic and LoRA worklists from the union of inputs
- copy single-source layers exactly and merge available providers
- keep logical LoRA groups canonical, atomic, and collision-safe
- retain mismatch, dtype, quantization, streaming, and OOM contracts

.comfyignore

@@ -0,0 +1 @@
+tests/

__init__.py

@@ -20,6 +20,7 @@ from .nodes.merger import (
     ModelThreeMerger, TextEncoderThreeMerger, LoRAThreeMerger,
     CheckpointThreeMerger, EmbeddingThreeMerger
 )
+from .nodes.consensus_merger import CWB_MERGER_NODES
 from .nodes.lora_extract_svd import (
     LoRAExtractFixed, LoRAExtractRatio, LoRAExtractQuantile,
     LoRAExtractKnee, LoRAExtractFrobenius
@@ -68,6 +69,8 @@ class ModelUtilsExtension(ComfyExtension):
             # Three-Model Mergers
             ModelThreeMerger, TextEncoderThreeMerger, LoRAThreeMerger,
             CheckpointThreeMerger, EmbeddingThreeMerger,
+            # Dedicated CWB Mergers
+            *CWB_MERGER_NODES,
             # LoRA Extraction
             LoRAExtractFixed, LoRAExtractRatio, LoRAExtractQuantile,
             LoRAExtractKnee, LoRAExtractFrobenius,

docs/consensus_mergers.md

@@ -0,0 +1,109 @@
+# Consensus-Weighted Blending Mergers
+
+The dedicated CWB nodes merge two or three safetensors files using
+Consensus-Weighted Blending. They calculate an element-wise mean or median
+consensus, compare each aligned source vector to that consensus, and normalize
+similarity-derived weights before producing the output vector.
+
+## Node families
+
+Two-input and three-input variants are provided for checkpoints, standalone
+diffusion models, text encoders, LoRAs, and embeddings.
+
+Model A supplies output metadata and anchors shared-layer shape, naming, and
+mismatch behavior. The output key set is the union of all inputs. A valid
+tensor found only in a secondary input is copied unchanged. When Model A lacks
+a tensor that is present in multiple secondary inputs, those available sources
+are CWB-merged without inserting a zero contribution for Model A. Embedding
+mergers additionally use the longest compatible first dimension as their
+alignment reference.
+
+## Presets and custom controls
+
+`baseline` is the default. The standard clarity, smooth, varied, and diversity
+presets are joined by `power_blend` and the DSC presets demonstrated by the CWB
+conditioning implementation. Select `custom` to make every manual CWB control
+authoritative.
+
+Similarity alignment greedily matches source rows to the reference by cosine
+similarity. Index alignment keeps absolute row positions. Position weight can
+bias similarity matches toward nearby normalized positions. Preserve Common
+Prefix copies the longest numerically identical leading row span directly from
+the first input.
+
+Inputs have equal prior weight. The similarity calculation supplies the
+effective contribution for each aligned vector. If every candidate is rejected
+or receives zero weight, CWB falls back to equal weighting.
+
+## Missing tensors and filtering
+
+- `skip` preserves Model A when an anchored input is missing or incompatible.
+  In embedding-union mode it omits that source for the affected key.
+- `zeros` supplies a compatible zero tensor for the missing source.
+- `error` stops the merge.
+- Exclude patterns preserve the anchored source tensor.
+- Discard patterns remove the matching output tensor or logical LoRA layer.
+
+The missing-input modes above apply to Model-A-owned layers. Model A being
+absent from a secondary-only layer is not itself a mismatch. A shape conflict
+between multiple available secondary providers does use the selected mismatch
+mode, with the earliest available input as its preservation anchor.
+
+Patterns use regular expressions by default. Enable Glob Patterns to use glob
+syntax instead.
+
+## LoRA behavior
+
+LoRA inputs use the same parser as the resize and multi-merge nodes. It accepts
+all seven low-rank A/B spellings recognized by ComfyUI's `LoRAAdapter`, plus
+direct `.diff`, `.diff_b`, `.w_norm`, `.b_norm`, and `.set_weight` layers.
+
+Recognized diffusion-model outputs use the canonical
+`diffusion_model.<layer>.lora_A.weight` / `.lora_B.weight` convention.
+Secondary formats are matched by normalized logical layer name. Differing
+ranks are zero-padded like the DARE/TIES mergers: A/down tensors on dimension 0
+and B/up tensors on dimension 1. An existing anchor-source alpha key is updated
+to the resulting maximum rank; no alpha key is invented when the anchor has
+none.
+Similarity alignment operates on paired latent-rank components. A rows and B
+columns share one mapping; fixed input/output feature axes are never reordered.
+Input alpha scaling is absorbed into the B factor before blending, and global
+scale is applied once to the resulting pair rather than once per factor.
+Incomplete pairs and unrecognized tensors are copied from the earliest
+available source unchanged.
+Companion-bearing groups (`lora_mid`, reshape, DoRA, or set-weight) are kept
+atomically from their earliest available source rather than partially
+transformed. Secondary-only logical groups are included automatically: a group
+from one source is copied unchanged, while compatible groups from multiple
+secondary sources are merged using only those sources. Recognized roles are
+written with the same canonical output convention as shared layers.
+
+`include_1d_diffs` is disabled by default. Disabled shared 1D direct layers
+preserve Model A, while secondary-only layers preserve their earliest source.
+Enabled 1D direct layers participate as complete tensors and are always saved
+in FP32.
+
+## Precision and quantized inputs
+
+CWB computes in FP32. Unless Override Dtype is enabled, any participating FP32
+source keeps the generated logical layer in FP32. Guarded low-bit tensors and
+enabled 1D direct diffs are never downcast by the override.
+
+ComfyUI/comfy-kitchen quantized inputs are rejected before an output writer is
+opened. Files with three or more bare INT8, UINT8, FP8, or FP4 tensors are also
+rejected. One or two isolated low-bit tensors produce one warning per input and
+are preserved without CWB arithmetic; an affected LoRA causes its complete
+logical layer to be preserved.
+
+## Streaming and failure safety
+
+Model parameters and direct patches use fixed-coordinate blending; similarity
+row matching is limited to embeddings and LoRA rank components. Each logical
+layer is loaded, transferred to the processing device, completed, copied back
+to CPU, queued for writing, and released before the next layer. Outputs are
+written to a temporary sibling and atomically published only after every layer
+and asynchronous write succeeds. Failed merges do not replace or finalize the
+requested output. A CUDA OOM retries only the affected layer on CPU after
+releasing the failed GPU working set; failure of that retry aborts atomically.
+Generated files are published under the matching category inside
+`folder_paths.models_dir`, never ComfyUI's general output directory.

docs/merger_2_model_modes.md

@@ -121,6 +121,15 @@ When merging models with different layer structures (e.g., fine-tuned models wit
 
 ---
 
+## Dtype Preservation & Override
+
+By default, the merger preserves the highest precision `dtype` for each key found across all active source models (Model A and Model B) and the requested `save_dtype`.
+
+- **Preserve Higher Precision**: If a key is `float32` in any of the source models, but you requested `save_dtype="bf16"` or `"fp16"`, that key will be saved as `float32` anyway. This prevents degrading critical high-precision layers (such as normalization layers or layers with restored outliers).
+- **Explicit Override**: If you prefer to force the entire model to be saved strictly as the selected `save_dtype` (e.g. for complete downcasting to `bf16`), toggle `override_dtype` to `True`.
+
+---
+
 ## Layer Filtering (Regex Patterns)
 
 Use regex patterns to control which layers are merged:

docs/merger_3_model_modes.md

@@ -67,6 +67,15 @@ When merging models with different layer structures, the `mismatch_mode` paramet
 
 ---
 
+## Dtype Preservation & Override
+
+By default, the merger preserves the highest precision `dtype` for each key found across all active source models (Model A, B, and C) and the requested `save_dtype`.
+
+- **Preserve Higher Precision**: If a key is `float32` in any of the active source models, but you requested `save_dtype="bf16"` or `"fp16"`, that key will be saved as `float32` anyway. This prevents degrading critical high-precision layers (such as normalization layers or layers with restored outliers).
+- **Explicit Override**: If you prefer to force the entire model to be saved strictly as the selected `save_dtype` (e.g. for complete downcasting to `bf16`), toggle `override_dtype` to `True`.
+
+---
+
 ## Layer Filtering (Regex Patterns)
 
 Use regex patterns to control which layers are merged:

nodes/dora_extract_wd.py

@@ -551,6 +551,14 @@ def extract_dora_from_files(
                     dora_scale = None
                     del tensor_b
                 else:
+                    # 1-D weights (e.g. x_pad_token, norm .weight) have no
+                    # weight-decomposition direction and are skipped below
+                    # anyway; bail out before the norm, which would index
+                    # dim=1 and raise on a 1-D tensor.
+                    if tensor_a.ndim < 2:
+                        del tensor_a, tensor_b
+                        return "skipped", None
+
                     # Weight Decomposition calculation
                     is_conv_dim = tensor_a.ndim == 4
                     

nodes/lora_extract_svd.py

@@ -19,6 +19,7 @@ from .device_utils import (
 )
 
 from unifiedefficientloader import MemoryEfficientSafeOpen, transfer_to_gpu_pinned, IncrementalSafetensorsWriter
+from .quantization_guard import inspect_low_bit_input
 
 
 
@@ -458,6 +459,7 @@ def extract_lora_from_files(
     lazy_load: bool = True,
     force_clear_cache: bool = True,
     glob_skip_patterns: bool = False,
+    include_1d_diffs: bool = False,
 ) -> None:
     """
     Extract LoRA from difference between two models, writing incrementally to disk.
@@ -469,7 +471,7 @@ def extract_lora_from_files(
         linear_param: Mode parameter for linear layers
         conv_param: Mode parameter for conv layers
         device: Computation device
-        save_dtype: Output dtype
+        save_dtype: Output dtype for layers whose sources are not FP32
         output_path: Full path to output safetensors file
         linear_max_rank: Max rank for linear layers
         conv_max_rank: Max rank for conv layers
@@ -480,6 +482,8 @@ def extract_lora_from_files(
         chunk_large_layers: Enable chunked extraction
         glob_skip_patterns: When True, treat skip_patterns as glob (* wildcard).
                             When False (default), treat as Python regex.
+        include_1d_diffs: Save 1D tensors in FP32 and keys ending in .scale or
+                          .lin as full .diff patches instead of skipping them.
     """
     save_torch_dtype = {
         "fp32": torch.float32,
@@ -498,10 +502,22 @@ def extract_lora_from_files(
     handler_b = MemoryEfficientSafeOpen(model_b_path, low_memory=lazy_load)
 
     try:
+        low_bit_a = inspect_low_bit_input(handler_a, f"Model A ({model_a_path})", "LoRA Extract")
+        low_bit_b = inspect_low_bit_input(handler_b, f"Model B ({model_b_path})", "LoRA Extract")
         keys_a = set(handler_a.keys())
         keys_b = set(handler_b.keys())
-        weight_keys = [k for k in keys_a if k.endswith(".weight")]
-        pbar = comfy.utils.ProgressBar(len(weight_keys))
+        direct_diff_suffixes = (".scale", ".lin")
+        extraction_keys = [
+            k for k in keys_a
+            if k not in low_bit_a
+            and k not in low_bit_b
+            and (k.endswith(".weight")
+            or (
+                include_1d_diffs
+                and (len(handler_a.get_shape(k)) == 1 or k.endswith(direct_diff_suffixes))
+            ))
+        ]
+        pbar = comfy.utils.ProgressBar(len(extraction_keys))
         stats = {"extracted": 0, "full": 0, "skipped": 0, "chunked": 0}
 
         def _process_layer(key):
@@ -510,6 +526,13 @@ def extract_lora_from_files(
             if _matches_any_pattern(key, skip_patterns, glob_mode=glob_skip_patterns):
                 return "skipped", None
 
+            source_dtypes = [handler_a.get_dtype(key)]
+            if key in keys_b:
+                source_dtypes.append(handler_b.get_dtype(key))
+            layer_save_dtype = (
+                torch.float32 if torch.float32 in source_dtypes else save_torch_dtype
+            )
+
             # Load tensors with pinned memory for CUDA
             use_pinned = device == 'cuda'
 
@@ -561,7 +584,18 @@ def extract_lora_from_files(
                 del weight_diff
                 return "skipped", None
 
-            # Skip 1D tensors
+            # SVD requires matrix-shaped tensors. Optionally preserve 1D weights
+            # and scale/lin parameters as exact runtime-applicable diff patches.
+            is_direct_diff = weight_diff.ndim == 1 or key.endswith(direct_diff_suffixes)
+            if include_1d_diffs and is_direct_diff:
+                direct_diff_dtype = torch.float32 if weight_diff.ndim == 1 else layer_save_dtype
+                layer_results = {
+                    _format_direct_diff_key(key, lora_name):
+                        weight_diff.to(direct_diff_dtype).cpu().contiguous()
+                }
+                del weight_diff
+                return "full", layer_results
+
             if weight_diff.ndim < 2:
                 del weight_diff
                 return "skipped", None
@@ -588,8 +622,8 @@ def extract_lora_from_files(
                             weight_diff, num_chunks, mode, linear_param, device, linear_max_rank
                         )
                         if lora_up is not None:
-                            layer_results[f"{lora_name}.lora_B.weight"] = lora_up.to(save_torch_dtype).cpu().contiguous()
-                            layer_results[f"{lora_name}.lora_A.weight"] = lora_down.to(save_torch_dtype).cpu().contiguous()
+                            layer_results[f"{lora_name}.lora_B.weight"] = lora_up.to(layer_save_dtype).cpu().contiguous()
+                            layer_results[f"{lora_name}.lora_A.weight"] = lora_down.to(layer_save_dtype).cpu().contiguous()
                             del weight_diff
                             return "chunked", layer_results
 
@@ -599,12 +633,12 @@ def extract_lora_from_files(
 
             # Store result
             if mode_str == "full":
-                layer_results[f"{lora_name}.diff"] = weight_diff.to(save_torch_dtype).cpu().contiguous()
+                layer_results[f"{lora_name}.diff"] = weight_diff.to(layer_save_dtype).cpu().contiguous()
                 status = "full"
             else:
                 lora_down, lora_up, _ = result
-                layer_results[f"{lora_name}.lora_A.weight"] = lora_down.to(save_torch_dtype).cpu().contiguous()
-                layer_results[f"{lora_name}.lora_B.weight"] = lora_up.to(save_torch_dtype).cpu().contiguous()
+                layer_results[f"{lora_name}.lora_A.weight"] = lora_down.to(layer_save_dtype).cpu().contiguous()
+                layer_results[f"{lora_name}.lora_B.weight"] = lora_up.to(layer_save_dtype).cpu().contiguous()
                 status = "extracted"
 
             del weight_diff
@@ -613,7 +647,7 @@ def extract_lora_from_files(
         writer = IncrementalSafetensorsWriter(output_path)
         writer.__enter__()
         try:
-            for key in tqdm(weight_keys, desc="Extracting LoRA", unit="layers"):
+            for key in tqdm(extraction_keys, desc="Extracting LoRA", unit="layers"):
                 status, layer_sd = _process_layer(key)
                 stats[status] += 1
                 if layer_sd:
@@ -704,6 +738,13 @@ def _format_lora_key(key: str) -> str:
     return f"diffusion_model.{key}"
 
 
+def _format_direct_diff_key(source_key: str, lora_name: str) -> str:
+    """Map a full delta to ComfyUI's canonical direct-patch key."""
+    if source_key.endswith(".bias"):
+        return f"{lora_name[:-5]}.diff_b"
+    return f"{lora_name}.diff"
+
+
 def _get_common_inputs():
     return [
         io.Boolean.Input("lazy_load", default=True, tooltip="Low memory mode: load tensors from disk on demand"),
@@ -716,13 +757,16 @@ def _get_common_inputs():
                       tooltip="Skip layers with max difference below this"),
         io.Combo.Input("mismatch_mode", options=["skip", "zeros", "error"], default="skip"),
         io.String.Input("output_filename", default="extracted_lora"),
-        io.Combo.Input("save_dtype", options=["fp16", "bf16", "fp32"], default="fp16"),
+        io.Combo.Input("save_dtype", options=["fp16", "bf16", "fp32"], default="fp16",
+                       tooltip="Output dtype; layers stored as FP32 in either source remain FP32"),
         io.Combo.Input("device", options=["cuda", "cpu"], default="cuda"),
         io.String.Input("skip_patterns", default="", multiline=True,
                        tooltip="Patterns for layers to skip (regex or glob depending on glob_skip_patterns)"),
         io.Boolean.Input("glob_skip_patterns", default=False,
                         tooltip="When True, skip_patterns use glob syntax (* = any sequence, ? = any char, dots are literal). "
                                 "When False (default), patterns are Python regex matched as substrings."),
+        io.Boolean.Input("include_1d_diffs", default=False,
+                        tooltip="Include 1D tensors as FP32 and keys ending in .scale or .lin as full .diff patches"),
     ]
 
 
@@ -753,7 +797,8 @@ class LoRAExtractFixed(io.ComfyNode):
     @classmethod
     def execute(cls, model_a, model_b, linear_dim, conv_dim, svd_niter, chunk_large_layers,
                 clamp_quantile, min_diff, mismatch_mode, output_filename,
-                save_dtype, device, skip_patterns, glob_skip_patterns, lazy_load, force_clear_cache) -> io.NodeOutput:
+                save_dtype, device, skip_patterns, glob_skip_patterns, lazy_load, force_clear_cache,
+                include_1d_diffs=False) -> io.NodeOutput:
 
         model_a_path = folder_paths.get_full_path_or_raise("diffusion_models", model_a)
         model_b_path = folder_paths.get_full_path_or_raise("diffusion_models", model_b)
@@ -763,7 +808,7 @@ class LoRAExtractFixed(io.ComfyNode):
             model_a_path, model_b_path, "fixed", linear_dim, conv_dim,
             device, save_dtype, output_path, linear_dim, conv_dim,
             clamp_quantile, min_diff, skip_patterns, mismatch_mode, chunk_large_layers, svd_niter,
-            lazy_load, force_clear_cache, glob_skip_patterns
+            lazy_load, force_clear_cache, glob_skip_patterns, include_1d_diffs
         )
 
         return io.NodeOutput(output_path)
@@ -798,7 +843,8 @@ class LoRAExtractRatio(io.ComfyNode):
     @classmethod
     def execute(cls, model_a, model_b, linear_ratio, conv_ratio, linear_max_rank, conv_max_rank,
                 chunk_large_layers, clamp_quantile, min_diff, mismatch_mode, output_filename,
-                save_dtype, device, skip_patterns, glob_skip_patterns, lazy_load, force_clear_cache) -> io.NodeOutput:
+                save_dtype, device, skip_patterns, glob_skip_patterns, lazy_load, force_clear_cache,
+                include_1d_diffs=False) -> io.NodeOutput:
 
         model_a_path = folder_paths.get_full_path_or_raise("diffusion_models", model_a)
         model_b_path = folder_paths.get_full_path_or_raise("diffusion_models", model_b)
@@ -809,7 +855,7 @@ class LoRAExtractRatio(io.ComfyNode):
             device, save_dtype, output_path, linear_max_rank, conv_max_rank,
             clamp_quantile, min_diff, skip_patterns, mismatch_mode, chunk_large_layers,
             lazy_load=lazy_load, force_clear_cache=force_clear_cache,
-            glob_skip_patterns=glob_skip_patterns
+            glob_skip_patterns=glob_skip_patterns, include_1d_diffs=include_1d_diffs
         )
 
         return io.NodeOutput(output_path)
@@ -844,7 +890,8 @@ class LoRAExtractQuantile(io.ComfyNode):
     @classmethod
     def execute(cls, model_a, model_b, linear_quantile, conv_quantile, linear_max_rank, conv_max_rank,
                 chunk_large_layers, clamp_quantile, min_diff, mismatch_mode, output_filename,
-                save_dtype, device, skip_patterns, glob_skip_patterns, lazy_load, force_clear_cache) -> io.NodeOutput:
+                save_dtype, device, skip_patterns, glob_skip_patterns, lazy_load, force_clear_cache,
+                include_1d_diffs=False) -> io.NodeOutput:
 
         model_a_path = folder_paths.get_full_path_or_raise("diffusion_models", model_a)
         model_b_path = folder_paths.get_full_path_or_raise("diffusion_models", model_b)
@@ -855,7 +902,7 @@ class LoRAExtractQuantile(io.ComfyNode):
             device, save_dtype, output_path, linear_max_rank, conv_max_rank,
             clamp_quantile, min_diff, skip_patterns, mismatch_mode, chunk_large_layers,
             lazy_load=lazy_load, force_clear_cache=force_clear_cache,
-            glob_skip_patterns=glob_skip_patterns
+            glob_skip_patterns=glob_skip_patterns, include_1d_diffs=include_1d_diffs
         )
 
         return io.NodeOutput(output_path)
@@ -888,7 +935,8 @@ class LoRAExtractKnee(io.ComfyNode):
     @classmethod
     def execute(cls, model_a, model_b, knee_method, linear_max_rank, conv_max_rank,
                 chunk_large_layers, clamp_quantile, min_diff, mismatch_mode, output_filename,
-                save_dtype, device, skip_patterns, glob_skip_patterns, lazy_load, force_clear_cache) -> io.NodeOutput:
+                save_dtype, device, skip_patterns, glob_skip_patterns, lazy_load, force_clear_cache,
+                include_1d_diffs=False) -> io.NodeOutput:
 
         model_a_path = folder_paths.get_full_path_or_raise("diffusion_models", model_a)
         model_b_path = folder_paths.get_full_path_or_raise("diffusion_models", model_b)
@@ -899,7 +947,7 @@ class LoRAExtractKnee(io.ComfyNode):
             device, save_dtype, output_path, linear_max_rank, conv_max_rank,
             clamp_quantile, min_diff, skip_patterns, mismatch_mode, chunk_large_layers,
             lazy_load=lazy_load, force_clear_cache=force_clear_cache,
-            glob_skip_patterns=glob_skip_patterns
+            glob_skip_patterns=glob_skip_patterns, include_1d_diffs=include_1d_diffs
         )
 
         return io.NodeOutput(output_path)
@@ -934,7 +982,8 @@ class LoRAExtractFrobenius(io.ComfyNode):
     @classmethod
     def execute(cls, model_a, model_b, linear_target, conv_target, linear_max_rank, conv_max_rank,
                 chunk_large_layers, clamp_quantile, min_diff, mismatch_mode, output_filename,
-                save_dtype, device, skip_patterns, glob_skip_patterns, lazy_load, force_clear_cache) -> io.NodeOutput:
+                save_dtype, device, skip_patterns, glob_skip_patterns, lazy_load, force_clear_cache,
+                include_1d_diffs=False) -> io.NodeOutput:
 
         model_a_path = folder_paths.get_full_path_or_raise("diffusion_models", model_a)
         model_b_path = folder_paths.get_full_path_or_raise("diffusion_models", model_b)
@@ -945,7 +994,7 @@ class LoRAExtractFrobenius(io.ComfyNode):
             device, save_dtype, output_path, linear_max_rank, conv_max_rank,
             clamp_quantile, min_diff, skip_patterns, mismatch_mode, chunk_large_layers,
             lazy_load=lazy_load, force_clear_cache=force_clear_cache,
-            glob_skip_patterns=glob_skip_patterns
+            glob_skip_patterns=glob_skip_patterns, include_1d_diffs=include_1d_diffs
         )
 
         return io.NodeOutput(output_path)

nodes/merger.py

@@ -12,6 +12,8 @@ from .device_utils import (
 )
 
 from unifiedefficientloader import MemoryEfficientSafeOpen, transfer_to_gpu_pinned, IncrementalSafetensorsWriter
+from .quantization_guard import inspect_low_bit_input, write_preserved_tensor
+from .lora_resize import is_direct_diff_key
 
 
 def load_documentation_from_file(filename):
@@ -105,6 +107,18 @@ class MergerLogic:
         all_keys = primary_handler.keys()
         metadata = primary_handler.metadata()
 
+        low_bit_keys_by_name = {}
+        if model_type == "loras":
+            try:
+                for name, handler in handlers.items():
+                    low_bit_keys_by_name[name] = inspect_low_bit_input(
+                        handler, f"LoRA ({name})", "Generic LoRA Merge"
+                    )
+            except Exception:
+                for handler in handlers.values():
+                    handler.__exit__(None, None, None)
+                raise
+
         # Convert mismatch_mode string to enum
         mismatch_mode_str = recipe_params.get('mismatch_mode', 'skip')
         mismatch_mode = MissingTensorBehavior(mismatch_mode_str)
@@ -132,6 +146,26 @@ class MergerLogic:
         pbar = comfy.utils.ProgressBar(len(all_keys))
         save_dtype = recipe_params.pop('save_dtype')
         save_torch_dtype = {"fp32": torch.float32, "fp16": torch.float16, "bf16": torch.bfloat16}.get(save_dtype)
+        override_dtype = recipe_params.pop('override_dtype', False)
+        include_1d_diffs = recipe_params.pop('include_1d_diffs', False)
+
+        def determine_target_dtype(original_dtypes, target_dtype, override):
+            if override:
+                return target_dtype
+            priority_map = {
+                torch.float32: 3,
+                torch.bfloat16: 2,
+                torch.float16: 2,
+            }
+            highest_dtype = target_dtype
+            highest_priority = priority_map.get(highest_dtype, 1)
+            for dtype in original_dtypes:
+                p = priority_map.get(dtype, 1)
+                if p > highest_priority:
+                    highest_priority = p
+                    highest_dtype = dtype
+            return highest_dtype
+
         recipe_params.update({"handlers": handlers})
         process_device = recipe_params.get('device', 'cpu')
         process_dtype = recipe_params.get('dtype', torch.float32)
@@ -142,8 +176,7 @@ class MergerLogic:
         error_keys = []
 
         output_folder = "loras" if calc_mode == "SVD LoRA Extraction" else model_type
-        # Use [-1] for diffusion_models to get the actual diffusion_models folder, not legacy unet
-        output_dir = folder_paths.get_folder_paths(output_folder)[-1]
+        output_dir = os.path.join(folder_paths.models_dir, output_folder)
         os.makedirs(output_dir, exist_ok=True)
         output_filename = recipe_params.get("output_filename")
         output_path = os.path.join(output_dir, f"{output_filename}.safetensors")
@@ -174,6 +207,14 @@ class MergerLogic:
 
         with torch.no_grad():
             for key in tqdm(all_keys, desc="Merging layers", unit="layers"):
+                preserve_low_bit = model_type == "loras" and any(
+                    key in low_bit_keys for low_bit_keys in low_bit_keys_by_name.values()
+                )
+                if preserve_low_bit:
+                    _flush_batch()
+                    write_preserved_tensor(writer, key, primary_handler)
+                    pbar.update(1)
+                    continue
                 # Check discard patterns first - skip entirely
                 if _matches_any_pattern(key, discard_patterns, glob_mode=glob_mode):
                     discarded_keys += 1
@@ -181,6 +222,22 @@ class MergerLogic:
 
                 # Pre-load Model A's tensor with pinned memory for CUDA
                 cpu_tensor = primary_handler.get_tensor(key)
+
+                # Determine original dtypes across all active models for this key
+                original_dtypes = [primary_handler.get_dtype(key)]
+                for name, handler in handlers.items():
+                    if name != primary_model_name and key in handler.keys():
+                        original_dtypes.append(handler.get_dtype(key))
+
+                target_dtype = determine_target_dtype(original_dtypes, save_torch_dtype, override_dtype)
+                preserve_model_a_1d = model_type == "loras" and cpu_tensor.ndim == 1 and not include_1d_diffs
+                if preserve_model_a_1d:
+                    target_dtype = determine_target_dtype(
+                        [primary_handler.get_dtype(key)], save_torch_dtype, override_dtype
+                    )
+                elif model_type == "loras" and is_direct_diff_key(key) and cpu_tensor.ndim == 1:
+                    target_dtype = torch.float32
+
                 if process_device == 'cuda':
                     tensor_a = transfer_to_gpu_pinned(cpu_tensor, process_device, process_dtype)
                 else:
@@ -188,13 +245,14 @@ class MergerLogic:
                 del cpu_tensor
 
                 # Check exclude patterns - use Model A only, no merge
-                if _matches_any_pattern(key, exclude_patterns, glob_mode=glob_mode):
-                    t = tensor_a.detach().to(save_torch_dtype).cpu()
+                if preserve_model_a_1d or _matches_any_pattern(key, exclude_patterns, glob_mode=glob_mode):
+                    t = tensor_a.detach().to(target_dtype).cpu()
 
                     batch_buffer[key] = t
                     batch_bytes += t.numel() * t.element_size()
                     batch_key_count += 1
-                    excluded_keys += 1
+                    if not preserve_model_a_1d:
+                        excluded_keys += 1
                     del tensor_a
                     if (batch_bytes >= flush_threshold_bytes or batch_key_count >= 32):
                         _flush_batch()
@@ -224,7 +282,7 @@ class MergerLogic:
 
                 if isinstance(result, dict):
                     for r_key, r_tensor in result.items():
-                        t = r_tensor.detach().to(save_torch_dtype).cpu()
+                        t = r_tensor.detach().to(target_dtype).cpu()
 
                         batch_buffer[r_key] = t
                         batch_bytes += t.numel() * t.element_size()
@@ -238,7 +296,7 @@ class MergerLogic:
                             slices = tuple(slice(0, min(res_s, tgt_s)) for res_s, tgt_s in zip(result.shape, target_shape))
                             result = result[slices]
 
-                    t = result.detach().to(save_torch_dtype).cpu()
+                    t = result.detach().to(target_dtype).cpu()
 
                     batch_buffer[key] = t
                     batch_bytes += t.numel() * t.element_size()
@@ -275,8 +333,7 @@ class MergerLogic:
             handler.__exit__(None, None, None)
 
         output_folder = "loras" if calc_mode == "SVD LoRA Extraction" else model_type
-        # Use [-1] for diffusion_models to get the actual diffusion_models folder, not legacy unet
-        output_dir = folder_paths.get_folder_paths(output_folder)[-1]
+        output_dir = os.path.join(folder_paths.models_dir, output_folder)
         os.makedirs(output_dir, exist_ok=True)
         output_filename = recipe_params.get("output_filename")
         output_path = os.path.join(output_dir, f"{output_filename}.safetensors")
@@ -323,6 +380,7 @@ class CheckpointTwoMerger(io.ComfyNode):
                                          "When False (default), patterns are Python regex matched as substrings."),
                 io.Boolean.Input("lazy_load", default=True, tooltip="Low memory mode: load tensors from disk on demand"),
                 io.Boolean.Input("force_clear_cache", default=True, tooltip="Clear CUDA cache after each layer"),
+                io.Boolean.Input("override_dtype", default=False, tooltip="Force the entire model to be saved as the selected save_dtype. If False (default), higher precision dtypes are preserved."),
             ],
             outputs=[
                 io.String.Output(display_name="output_filename"),
@@ -335,7 +393,7 @@ class CheckpointTwoMerger(io.ComfyNode):
                 calc_mode: str, mismatch_mode: str, alignment_mode: str, alpha: float, beta: float,
                 gamma: float, delta: float, epsilon: float, zeta: float, seed: int, output_filename: str, save_dtype: str,
                 process_device: str, exclude_patterns: str, discard_patterns: str,
-                glob_patterns: bool, lazy_load: bool, force_clear_cache: bool) -> io.NodeOutput:
+                glob_patterns: bool, lazy_load: bool, force_clear_cache: bool, override_dtype: bool) -> io.NodeOutput:
         doc = load_documentation_from_file('merger_2_model_modes.md')
         if execution_mode == "DOCUMENTATION ONLY":
             return io.NodeOutput("Documentation mode active. No merge performed.", doc)
@@ -344,7 +402,7 @@ class CheckpointTwoMerger(io.ComfyNode):
             "model_a": model_a, "model_b": model_b, "calc_mode": calc_mode,
             "mismatch_mode": mismatch_mode, "alignment_mode": alignment_mode,
             "alpha": alpha, "beta": beta, "gamma": gamma, "delta": delta, "epsilon": epsilon, "zeta": zeta, "seed": seed,
-            "output_filename": output_filename, "save_dtype": save_dtype,
+            "output_filename": output_filename, "save_dtype": save_dtype, "override_dtype": override_dtype,
             "device": process_device, "dtype": torch.float32,
             "exclude_patterns": exclude_patterns, "discard_patterns": discard_patterns,
             "glob_patterns": glob_patterns,
@@ -388,6 +446,7 @@ class ModelTwoMerger(io.ComfyNode):
                                          "When False (default), patterns are Python regex matched as substrings."),
                 io.Boolean.Input("lazy_load", default=True, tooltip="Low memory mode: load tensors from disk on demand"),
                 io.Boolean.Input("force_clear_cache", default=True, tooltip="Clear CUDA cache after each layer"),
+                io.Boolean.Input("override_dtype", default=False, tooltip="Force the entire model to be saved as the selected save_dtype. If False (default), higher precision dtypes are preserved."),
             ],
             outputs=[
                 io.String.Output(display_name="output_filename"),
@@ -400,7 +459,7 @@ class ModelTwoMerger(io.ComfyNode):
                 calc_mode: str, mismatch_mode: str, alignment_mode: str, alpha: float, beta: float,
                 gamma: float, delta: float, epsilon: float, zeta: float, seed: int, output_filename: str, save_dtype: str,
                 process_device: str, exclude_patterns: str, discard_patterns: str,
-                glob_patterns: bool, lazy_load: bool, force_clear_cache: bool) -> io.NodeOutput:
+                glob_patterns: bool, lazy_load: bool, force_clear_cache: bool, override_dtype: bool) -> io.NodeOutput:
         doc = load_documentation_from_file('merger_2_model_modes.md')
         if execution_mode == "DOCUMENTATION ONLY":
             return io.NodeOutput("Documentation mode active. No merge performed.", doc)
@@ -409,7 +468,7 @@ class ModelTwoMerger(io.ComfyNode):
             "model_a": model_a, "model_b": model_b, "calc_mode": calc_mode,
             "mismatch_mode": mismatch_mode, "alignment_mode": alignment_mode,
             "alpha": alpha, "beta": beta, "gamma": gamma, "delta": delta, "epsilon": epsilon, "zeta": zeta, "seed": seed,
-            "output_filename": output_filename, "save_dtype": save_dtype,
+            "output_filename": output_filename, "save_dtype": save_dtype, "override_dtype": override_dtype,
             "device": process_device, "dtype": torch.float32,
             "exclude_patterns": exclude_patterns, "discard_patterns": discard_patterns,
             "glob_patterns": glob_patterns,
@@ -453,6 +512,7 @@ class TextEncoderTwoMerger(io.ComfyNode):
                                          "When False (default), patterns are Python regex matched as substrings."),
                 io.Boolean.Input("lazy_load", default=True, tooltip="Low memory mode: load tensors from disk on demand"),
                 io.Boolean.Input("force_clear_cache", default=True, tooltip="Clear CUDA cache after each layer"),
+                io.Boolean.Input("override_dtype", default=False, tooltip="Force the entire model to be saved as the selected save_dtype. If False (default), higher precision dtypes are preserved."),
             ],
             outputs=[
                 io.String.Output(display_name="output_filename"),
@@ -465,7 +525,7 @@ class TextEncoderTwoMerger(io.ComfyNode):
                 calc_mode: str, mismatch_mode: str, alignment_mode: str, alpha: float, beta: float,
                 gamma: float, delta: float, epsilon: float, zeta: float, seed: int, output_filename: str, save_dtype: str,
                 process_device: str, exclude_patterns: str, discard_patterns: str,
-                glob_patterns: bool, lazy_load: bool, force_clear_cache: bool) -> io.NodeOutput:
+                glob_patterns: bool, lazy_load: bool, force_clear_cache: bool, override_dtype: bool) -> io.NodeOutput:
         doc = load_documentation_from_file('merger_2_model_modes.md')
         if execution_mode == "DOCUMENTATION ONLY":
             return io.NodeOutput("Documentation mode active. No merge performed.", doc)
@@ -474,7 +534,7 @@ class TextEncoderTwoMerger(io.ComfyNode):
             "model_a": model_a, "model_b": model_b, "calc_mode": calc_mode,
             "mismatch_mode": mismatch_mode, "alignment_mode": alignment_mode,
             "alpha": alpha, "beta": beta, "gamma": gamma, "delta": delta, "epsilon": epsilon, "zeta": zeta, "seed": seed,
-            "output_filename": output_filename, "save_dtype": save_dtype,
+            "output_filename": output_filename, "save_dtype": save_dtype, "override_dtype": override_dtype,
             "device": process_device, "dtype": torch.float32,
             "exclude_patterns": exclude_patterns, "discard_patterns": discard_patterns,
             "glob_patterns": glob_patterns,
@@ -518,6 +578,9 @@ class LoRATwoMerger(io.ComfyNode):
                                          "When False (default), patterns are Python regex matched as substrings."),
                 io.Boolean.Input("lazy_load", default=True, tooltip="Low memory mode: load tensors from disk on demand"),
                 io.Boolean.Input("force_clear_cache", default=True, tooltip="Clear CUDA cache after each layer"),
+                io.Boolean.Input("override_dtype", default=False, tooltip="Force merged non-1D tensors to save_dtype. Enabled 1D direct diffs remain FP32."),
+                io.Boolean.Input("include_1d_diffs", default=False,
+                                 tooltip="Merge 1D tensors. When disabled, preserve Model A's 1D tensors unchanged."),
             ],
             outputs=[
                 io.String.Output(display_name="output_filename"),
@@ -530,7 +593,8 @@ class LoRATwoMerger(io.ComfyNode):
                 calc_mode: str, mismatch_mode: str, alignment_mode: str, alpha: float, beta: float,
                 gamma: float, delta: float, epsilon: float, zeta: float, seed: int, output_filename: str, save_dtype: str,
                 process_device: str, exclude_patterns: str, discard_patterns: str,
-                glob_patterns: bool, lazy_load: bool, force_clear_cache: bool) -> io.NodeOutput:
+                glob_patterns: bool, lazy_load: bool, force_clear_cache: bool, override_dtype: bool,
+                include_1d_diffs: bool) -> io.NodeOutput:
         doc = load_documentation_from_file('merger_2_model_modes.md')
         if execution_mode == "DOCUMENTATION ONLY":
             return io.NodeOutput("Documentation mode active. No merge performed.", doc)
@@ -539,11 +603,12 @@ class LoRATwoMerger(io.ComfyNode):
             "model_a": model_a, "model_b": model_b, "calc_mode": calc_mode,
             "mismatch_mode": mismatch_mode, "alignment_mode": alignment_mode,
             "alpha": alpha, "beta": beta, "gamma": gamma, "delta": delta, "epsilon": epsilon, "zeta": zeta, "seed": seed,
-            "output_filename": output_filename, "save_dtype": save_dtype,
+            "output_filename": output_filename, "save_dtype": save_dtype, "override_dtype": override_dtype,
             "device": process_device, "dtype": torch.float32,
             "exclude_patterns": exclude_patterns, "discard_patterns": discard_patterns,
             "glob_patterns": glob_patterns,
             "lazy_load": lazy_load, "force_clear_cache": force_clear_cache,
+            "include_1d_diffs": include_1d_diffs,
         }
         model_names = {"model_a": model_a, "model_b": model_b}
         filename = MergerLogic.execute_merge(model_names, calc_mode, TWO_MODEL_MODES, recipe_params, cls.MODEL_TYPE)
@@ -583,6 +648,7 @@ class EmbeddingTwoMerger(io.ComfyNode):
                                          "When False (default), patterns are Python regex matched as substrings."),
                 io.Boolean.Input("lazy_load", default=True, tooltip="Low memory mode: load tensors from disk on demand"),
                 io.Boolean.Input("force_clear_cache", default=True, tooltip="Clear CUDA cache after each layer"),
+                io.Boolean.Input("override_dtype", default=False, tooltip="Force the entire model to be saved as the selected save_dtype. If False (default), higher precision dtypes are preserved."),
             ],
             outputs=[
                 io.String.Output(display_name="output_filename"),
@@ -595,7 +661,7 @@ class EmbeddingTwoMerger(io.ComfyNode):
                 calc_mode: str, mismatch_mode: str, alignment_mode: str, alpha: float, beta: float,
                 gamma: float, delta: float, epsilon: float, zeta: float, seed: int, output_filename: str, save_dtype: str,
                 process_device: str, exclude_patterns: str, discard_patterns: str,
-                glob_patterns: bool, lazy_load: bool, force_clear_cache: bool) -> io.NodeOutput:
+                glob_patterns: bool, lazy_load: bool, force_clear_cache: bool, override_dtype: bool) -> io.NodeOutput:
         doc = load_documentation_from_file('merger_2_model_modes.md')
         if execution_mode == "DOCUMENTATION ONLY":
             return io.NodeOutput("Documentation mode active. No merge performed.", doc)
@@ -604,7 +670,7 @@ class EmbeddingTwoMerger(io.ComfyNode):
             "model_a": model_a, "model_b": model_b, "calc_mode": calc_mode,
             "mismatch_mode": mismatch_mode, "alignment_mode": alignment_mode,
             "alpha": alpha, "beta": beta, "gamma": gamma, "delta": delta, "epsilon": epsilon, "zeta": zeta, "seed": seed,
-            "output_filename": output_filename, "save_dtype": save_dtype,
+            "output_filename": output_filename, "save_dtype": save_dtype, "override_dtype": override_dtype,
             "device": process_device, "dtype": torch.float32,
             "exclude_patterns": exclude_patterns, "discard_patterns": discard_patterns,
             "glob_patterns": glob_patterns,
@@ -651,6 +717,7 @@ class CheckpointThreeMerger(io.ComfyNode):
                                          "When False (default), patterns are Python regex matched as substrings."),
                 io.Boolean.Input("lazy_load", default=True, tooltip="Low memory mode: load tensors from disk on demand"),
                 io.Boolean.Input("force_clear_cache", default=True, tooltip="Clear CUDA cache after each layer"),
+                io.Boolean.Input("override_dtype", default=False, tooltip="Force the entire model to be saved as the selected save_dtype. If False (default), higher precision dtypes are preserved."),
             ],
             outputs=[
                 io.String.Output(display_name="output_filename"),
@@ -663,7 +730,7 @@ class CheckpointThreeMerger(io.ComfyNode):
                 calc_mode: str, mismatch_mode: str, alignment_mode: str, alpha: float, beta: float,
                 gamma: float, delta: float, epsilon: float, zeta: float, seed: int, output_filename: str, save_dtype: str,
                 process_device: str, exclude_patterns: str, discard_patterns: str,
-                glob_patterns: bool, lazy_load: bool, force_clear_cache: bool) -> io.NodeOutput:
+                glob_patterns: bool, lazy_load: bool, force_clear_cache: bool, override_dtype: bool) -> io.NodeOutput:
         doc = load_documentation_from_file('merger_3_model_modes.md')
         if execution_mode == "DOCUMENTATION ONLY":
             return io.NodeOutput("Documentation mode active. No merge performed.", doc)
@@ -672,7 +739,7 @@ class CheckpointThreeMerger(io.ComfyNode):
             "model_a": model_a, "model_b": model_b, "model_c": model_c, "calc_mode": calc_mode,
             "mismatch_mode": mismatch_mode, "alignment_mode": alignment_mode,
             "alpha": alpha, "beta": beta, "gamma": gamma, "delta": delta, "epsilon": epsilon, "zeta": zeta, "seed": seed,
-            "output_filename": output_filename, "save_dtype": save_dtype,
+            "output_filename": output_filename, "save_dtype": save_dtype, "override_dtype": override_dtype,
             "device": process_device, "dtype": torch.float32,
             "exclude_patterns": exclude_patterns, "discard_patterns": discard_patterns,
             "glob_patterns": glob_patterns,
@@ -717,6 +784,7 @@ class ModelThreeMerger(io.ComfyNode):
                                          "When False (default), patterns are Python regex matched as substrings."),
                 io.Boolean.Input("lazy_load", default=True, tooltip="Low memory mode: load tensors from disk on demand"),
                 io.Boolean.Input("force_clear_cache", default=True, tooltip="Clear CUDA cache after each layer"),
+                io.Boolean.Input("override_dtype", default=False, tooltip="Force the entire model to be saved as the selected save_dtype. If False (default), higher precision dtypes are preserved."),
             ],
             outputs=[
                 io.String.Output(display_name="output_filename"),
@@ -729,7 +797,7 @@ class ModelThreeMerger(io.ComfyNode):
                 calc_mode: str, mismatch_mode: str, alignment_mode: str, alpha: float, beta: float,
                 gamma: float, delta: float, epsilon: float, zeta: float, seed: int, output_filename: str, save_dtype: str,
                 process_device: str, exclude_patterns: str, discard_patterns: str,
-                glob_patterns: bool, lazy_load: bool, force_clear_cache: bool) -> io.NodeOutput:
+                glob_patterns: bool, lazy_load: bool, force_clear_cache: bool, override_dtype: bool) -> io.NodeOutput:
         doc = load_documentation_from_file('merger_3_model_modes.md')
         if execution_mode == "DOCUMENTATION ONLY":
             return io.NodeOutput("Documentation mode active. No merge performed.", doc)
@@ -738,7 +806,7 @@ class ModelThreeMerger(io.ComfyNode):
             "model_a": model_a, "model_b": model_b, "model_c": model_c, "calc_mode": calc_mode,
             "mismatch_mode": mismatch_mode, "alignment_mode": alignment_mode,
             "alpha": alpha, "beta": beta, "gamma": gamma, "delta": delta, "epsilon": epsilon, "zeta": zeta, "seed": seed,
-            "output_filename": output_filename, "save_dtype": save_dtype,
+            "output_filename": output_filename, "save_dtype": save_dtype, "override_dtype": override_dtype,
             "device": process_device, "dtype": torch.float32,
             "exclude_patterns": exclude_patterns, "discard_patterns": discard_patterns,
             "glob_patterns": glob_patterns,
@@ -783,6 +851,7 @@ class TextEncoderThreeMerger(io.ComfyNode):
                                          "When False (default), patterns are Python regex matched as substrings."),
                 io.Boolean.Input("lazy_load", default=True, tooltip="Low memory mode: load tensors from disk on demand"),
                 io.Boolean.Input("force_clear_cache", default=True, tooltip="Clear CUDA cache after each layer"),
+                io.Boolean.Input("override_dtype", default=False, tooltip="Force the entire model to be saved as the selected save_dtype. If False (default), higher precision dtypes are preserved."),
             ],
             outputs=[
                 io.String.Output(display_name="output_filename"),
@@ -795,7 +864,7 @@ class TextEncoderThreeMerger(io.ComfyNode):
                 calc_mode: str, mismatch_mode: str, alignment_mode: str, alpha: float, beta: float,
                 gamma: float, delta: float, epsilon: float, zeta: float, seed: int, output_filename: str, save_dtype: str,
                 process_device: str, exclude_patterns: str, discard_patterns: str,
-                glob_patterns: bool, lazy_load: bool, force_clear_cache: bool) -> io.NodeOutput:
+                glob_patterns: bool, lazy_load: bool, force_clear_cache: bool, override_dtype: bool) -> io.NodeOutput:
         doc = load_documentation_from_file('merger_3_model_modes.md')
         if execution_mode == "DOCUMENTATION ONLY":
             return io.NodeOutput("Documentation mode active. No merge performed.", doc)
@@ -804,7 +873,7 @@ class TextEncoderThreeMerger(io.ComfyNode):
             "model_a": model_a, "model_b": model_b, "model_c": model_c, "calc_mode": calc_mode,
             "mismatch_mode": mismatch_mode, "alignment_mode": alignment_mode,
             "alpha": alpha, "beta": beta, "gamma": gamma, "delta": delta, "epsilon": epsilon, "zeta": zeta, "seed": seed,
-            "output_filename": output_filename, "save_dtype": save_dtype,
+            "output_filename": output_filename, "save_dtype": save_dtype, "override_dtype": override_dtype,
             "device": process_device, "dtype": torch.float32,
             "exclude_patterns": exclude_patterns, "discard_patterns": discard_patterns,
             "glob_patterns": glob_patterns,
@@ -849,6 +918,9 @@ class LoRAThreeMerger(io.ComfyNode):
                                          "When False (default), patterns are Python regex matched as substrings."),
                 io.Boolean.Input("lazy_load", default=True, tooltip="Low memory mode: load tensors from disk on demand"),
                 io.Boolean.Input("force_clear_cache", default=True, tooltip="Clear CUDA cache after each layer"),
+                io.Boolean.Input("override_dtype", default=False, tooltip="Force merged non-1D tensors to save_dtype. Enabled 1D direct diffs remain FP32."),
+                io.Boolean.Input("include_1d_diffs", default=False,
+                                 tooltip="Merge 1D tensors. When disabled, preserve Model A's 1D tensors unchanged."),
             ],
             outputs=[
                 io.String.Output(display_name="output_filename"),
@@ -861,7 +933,8 @@ class LoRAThreeMerger(io.ComfyNode):
                 calc_mode: str, mismatch_mode: str, alignment_mode: str, alpha: float, beta: float,
                 gamma: float, delta: float, epsilon: float, zeta: float, seed: int, output_filename: str, save_dtype: str,
                 process_device: str, exclude_patterns: str, discard_patterns: str,
-                glob_patterns: bool, lazy_load: bool, force_clear_cache: bool) -> io.NodeOutput:
+                glob_patterns: bool, lazy_load: bool, force_clear_cache: bool, override_dtype: bool,
+                include_1d_diffs: bool) -> io.NodeOutput:
         doc = load_documentation_from_file('merger_3_model_modes.md')
         if execution_mode == "DOCUMENTATION ONLY":
             return io.NodeOutput("Documentation mode active. No merge performed.", doc)
@@ -870,11 +943,12 @@ class LoRAThreeMerger(io.ComfyNode):
             "model_a": model_a, "model_b": model_b, "model_c": model_c, "calc_mode": calc_mode,
             "mismatch_mode": mismatch_mode, "alignment_mode": alignment_mode,
             "alpha": alpha, "beta": beta, "gamma": gamma, "delta": delta, "epsilon": epsilon, "zeta": zeta, "seed": seed,
-            "output_filename": output_filename, "save_dtype": save_dtype,
+            "output_filename": output_filename, "save_dtype": save_dtype, "override_dtype": override_dtype,
             "device": process_device, "dtype": torch.float32,
             "exclude_patterns": exclude_patterns, "discard_patterns": discard_patterns,
             "glob_patterns": glob_patterns,
             "lazy_load": lazy_load, "force_clear_cache": force_clear_cache,
+            "include_1d_diffs": include_1d_diffs,
         }
         model_names = {"model_a": model_a, "model_b": model_b, "model_c": model_c}
         filename = MergerLogic.execute_merge(model_names, calc_mode, THREE_MODEL_MODES, recipe_params, cls.MODEL_TYPE)
@@ -915,6 +989,7 @@ class EmbeddingThreeMerger(io.ComfyNode):
                                          "When False (default), patterns are Python regex matched as substrings."),
                 io.Boolean.Input("lazy_load", default=True, tooltip="Low memory mode: load tensors from disk on demand"),
                 io.Boolean.Input("force_clear_cache", default=True, tooltip="Clear CUDA cache after each layer"),
+                io.Boolean.Input("override_dtype", default=False, tooltip="Force the entire model to be saved as the selected save_dtype. If False (default), higher precision dtypes are preserved."),
             ],
             outputs=[
                 io.String.Output(display_name="output_filename"),
@@ -927,7 +1002,7 @@ class EmbeddingThreeMerger(io.ComfyNode):
                 calc_mode: str, mismatch_mode: str, alignment_mode: str, alpha: float, beta: float,
                 gamma: float, delta: float, epsilon: float, zeta: float, seed: int, output_filename: str, save_dtype: str,
                 process_device: str, exclude_patterns: str, discard_patterns: str,
-                glob_patterns: bool, lazy_load: bool, force_clear_cache: bool) -> io.NodeOutput:
+                glob_patterns: bool, lazy_load: bool, force_clear_cache: bool, override_dtype: bool) -> io.NodeOutput:
         doc = load_documentation_from_file('merger_3_model_modes.md')
         if execution_mode == "DOCUMENTATION ONLY":
             return io.NodeOutput("Documentation mode active. No merge performed.", doc)
@@ -936,7 +1011,7 @@ class EmbeddingThreeMerger(io.ComfyNode):
             "model_a": model_a, "model_b": model_b, "model_c": model_c, "calc_mode": calc_mode,
             "mismatch_mode": mismatch_mode, "alignment_mode": alignment_mode,
             "alpha": alpha, "beta": beta, "gamma": gamma, "delta": delta, "epsilon": epsilon, "zeta": zeta, "seed": seed,
-            "output_filename": output_filename, "save_dtype": save_dtype,
+            "output_filename": output_filename, "save_dtype": save_dtype, "override_dtype": override_dtype,
             "device": process_device, "dtype": torch.float32,
             "exclude_patterns": exclude_patterns, "discard_patterns": discard_patterns,
             "glob_patterns": glob_patterns,
@@ -944,4 +1019,4 @@ class EmbeddingThreeMerger(io.ComfyNode):
         }
         model_names = {"model_a": model_a, "model_b": model_b, "model_c": model_c}
         filename = MergerLogic.execute_merge(model_names, calc_mode, THREE_MODEL_MODES, recipe_params, cls.MODEL_TYPE)
-        return io.NodeOutput(filename, doc)
+        return io.NodeOutput(filename, doc)

nodes/quantization_guard.py

@@ -0,0 +1,145 @@
+"""Fail-safe detection for quantized or isolated low-bit safetensors inputs."""
+
+import logging
+import json
+import struct
+
+import torch
+
+
+MAX_ISOLATED_LOW_BIT_TENSORS = 2
+
+
+def _low_bit_dtypes():
+    names = (
+        "int8",
+        "uint8",
+        "float4_e2m1fn_x2",
+        "float8_e4m3fn",
+        "float8_e4m3fnuz",
+        "float8_e5m2",
+        "float8_e5m2fnuz",
+        "float8_e8m0fnu",
+    )
+    return {getattr(torch, name) for name in names if hasattr(torch, name)}
+
+
+LOW_BIT_DTYPES = _low_bit_dtypes()
+LOW_BIT_STORAGE_CODES = {"I8", "U8", "F4"}
+UPSTREAM_WRITER_STORAGE_CODES = {
+    "F64", "F32", "F16", "BF16", "I64", "I32", "I16", "I8", "U8",
+    "U64", "U32", "U16", "BOOL", "C64", "F8_E5M2", "F8_E4M3",
+}
+
+
+def _header(handler):
+    if getattr(handler, "_header", None) is not None:
+        return handler._header
+    with open(handler.filename, "rb") as source:
+        header_size = struct.unpack("<Q", source.read(8))[0]
+        return json.loads(source.read(header_size).decode("utf-8"))
+
+
+def storage_dtype_code(handler, key: str) -> str | None:
+    entry = _header(handler).get(key)
+    return entry.get("dtype") if entry else None
+
+
+def _is_low_bit(handler, key: str) -> bool:
+    storage_code = storage_dtype_code(handler, key)
+    if storage_code in LOW_BIT_STORAGE_CODES or (
+        storage_code is not None and storage_code.startswith("F8_")
+    ):
+        return True
+    return handler.get_dtype(key) in LOW_BIT_DTYPES
+
+
+def inspect_low_bit_input(handler, label: str, operation: str) -> set[str]:
+    """Reject quantized models; return isolated low-bit keys that must not be transformed."""
+    keys = list(handler.keys())
+    metadata = handler.metadata() or {}
+    quant_keys = [key for key in keys if key.endswith(".comfy_quant")]
+    has_quant_metadata = "_quantization_metadata" in metadata
+    has_legacy_scaled_fp8 = any(key.endswith("scaled_fp8") for key in keys)
+    if quant_keys or has_quant_metadata or has_legacy_scaled_fp8:
+        raise ValueError(
+            f"[{operation}] {label} uses ComfyUI quantization metadata; quantized inputs are unsupported"
+        )
+
+    low_bit_keys = {key for key in keys if _is_low_bit(handler, key)}
+    if len(low_bit_keys) > MAX_ISOLATED_LOW_BIT_TENSORS:
+        raise ValueError(
+            f"[{operation}] {label} contains {len(low_bit_keys)} low-bit tensors; "
+            "casted or quantized inputs are unsupported"
+        )
+    if low_bit_keys:
+        logging.warning(
+            "[%s] %s contains %d isolated low-bit tensor(s); "
+            "preserving/excluding unchanged: %s",
+            operation,
+            label,
+            len(low_bit_keys),
+            ", ".join(sorted(low_bit_keys)),
+        )
+    return low_bit_keys
+
+
+def layer_has_low_bit(block_keys: dict, low_bit_keys: set[str]) -> bool:
+    return any(
+        block_keys.get(name) in low_bit_keys
+        for name in (
+            "down", "up", "alpha", "mid", "reshape", "dora_scale",
+            "diff", "diff_b", "w_norm", "b_norm", "set_weight",
+        )
+    )
+
+
+def write_preserved_tensor(writer, key: str, handler, output_key: str | None = None) -> None:
+    """Copy one tensor's original safetensors bytes and dtype into an active writer."""
+    destination = output_key or key
+    header = _header(handler)
+    entry = header[key]
+    if entry["dtype"] in UPSTREAM_WRITER_STORAGE_CODES:
+        writer.write(destination, handler.get_tensor(key).cpu().contiguous())
+        return
+
+    source_start, source_end = entry["data_offsets"]
+    byte_size = source_end - source_start
+
+    with writer._lock:
+        if destination in writer._manifest:
+            raise ValueError(f"Tensor '{destination}' has already been written.")
+        target_start = writer._current_data_offset
+        target_end = target_start + byte_size
+        writer._manifest[destination] = {
+            "dtype": entry["dtype"],
+            "shape": entry["shape"],
+            "data_offsets": [target_start, target_end],
+        }
+        writer._current_data_offset = target_end
+
+    source_path = handler.filename
+    source_absolute = 8 + getattr(handler, "_header_size", 0) + source_start
+    if not getattr(handler, "_header_size", None):
+        with open(source_path, "rb") as source:
+            source_absolute = 8 + struct.unpack("<Q", source.read(8))[0] + source_start
+    target_absolute = 8 + writer.max_header_bytes + target_start
+
+    def copy_raw():
+        try:
+            with open(source_path, "rb") as source:
+                source.seek(source_absolute)
+                remaining = byte_size
+                with writer._lock:
+                    writer._file.seek(target_absolute)
+                    while remaining:
+                        chunk = source.read(min(8 * 1024 * 1024, remaining))
+                        if not chunk:
+                            raise EOFError(f"Unexpected EOF while preserving tensor '{key}'")
+                        writer._file.write(chunk)
+                        remaining -= len(chunk)
+        finally:
+            writer._semaphore.release()
+
+    writer._semaphore.acquire()
+    writer._futures.append(writer._executor.submit(copy_raw))

pyproject.toml

@@ -1,7 +1,7 @@
 [project]
 name = "ComfyUI-ModelUtils"
 description = "[WIP]Custom nodes for handling, inspecting, modifying and creating various model files."
-version = "0.4.3"
+version = "0.4.6"
 license = { file = "LICENSE" }
 
 classifiers = [

tests/test_consensus_merger.py

@@ -0,0 +1,840 @@
+import importlib
+import sys
+import types
+from pathlib import Path
+
+import pytest
+import torch
+from safetensors.torch import load_file, save_file
+
+
+REPO_ROOT = Path(__file__).resolve().parents[1]
+PACKAGE_NAME = "modelutils_cwb_tests"
+
+
+def _load_module(name):
+    if PACKAGE_NAME not in sys.modules:
+        package = types.ModuleType(PACKAGE_NAME)
+        package.__path__ = [str(REPO_ROOT)]
+        sys.modules[PACKAGE_NAME] = package
+    return importlib.import_module(f"{PACKAGE_NAME}.{name}")
+
+
+@pytest.fixture(scope="module")
+def cwb():
+    return _load_module("nodes.consensus_merger")
+
+
+def _patch_io(monkeypatch, module, tmp_path, paths):
+    monkeypatch.setattr(module.folder_paths, "get_full_path", lambda _, name: paths.get(name))
+    monkeypatch.setattr(module.folder_paths, "get_folder_paths", lambda _: [str(tmp_path)])
+    monkeypatch.setattr(module.folder_paths, "models_dir", str(tmp_path))
+    monkeypatch.setattr(module, "prepare_for_large_operation", lambda *args, **kwargs: None)
+    monkeypatch.setattr(module, "cleanup_after_operation", lambda: None)
+
+
+def _result_path(tmp_path, category, result):
+    return tmp_path / category / result
+
+
+def _params(output_filename, **overrides):
+    params = {
+        "cwb_preset": "custom",
+        "consensus_type": "mean",
+        "alignment_method": "index",
+        "alignment_threshold": 0.4,
+        "similarity_threshold": 0.0,
+        "power_alpha": 2.0,
+        "diversity_beta": 0.0,
+        "rescale_norm": False,
+        "global_scale": 1.0,
+        "dynamic_similarity_contrast": False,
+        "soft_comfort_bandpass": False,
+        "position_weight": 0.0,
+        "preserve_common_prefix": False,
+        "mismatch_mode": "skip",
+        "output_filename": output_filename,
+        "save_dtype": "fp16",
+        "process_device": "cpu",
+        "exclude_patterns": "",
+        "discard_patterns": "",
+        "glob_patterns": False,
+        "lazy_load": True,
+        "force_clear_cache": False,
+        "override_dtype": False,
+        "include_1d_diffs": False,
+    }
+    params.update(overrides)
+    return params
+
+
+def test_preset_resolution_matches_extended_contract(cwb):
+    power = cwb.resolve_cwb_settings(cwb_preset="power_blend")
+    assert power.consensus_type == "median"
+    assert power.alignment_threshold == pytest.approx(0.9)
+    assert power.power_alpha == pytest.approx(8.0)
+    assert power.dynamic_similarity_contrast is True
+    assert power.soft_comfort_bandpass is False
+
+    baseline = cwb.resolve_cwb_settings(
+        cwb_preset="baseline",
+        alignment_method="index",
+        dynamic_similarity_contrast=True,
+        soft_comfort_bandpass=True,
+    )
+    assert baseline.alignment_method == "similarity"
+    assert baseline.dynamic_similarity_contrast is False
+    assert baseline.soft_comfort_bandpass is False
+
+    varied = cwb.resolve_cwb_settings(
+        cwb_preset="varied_merge",
+        global_scale=1.25,
+        position_weight=0.2,
+        preserve_common_prefix=True,
+    )
+    assert varied.global_scale == pytest.approx(1.25)
+    assert varied.position_weight == pytest.approx(0.2)
+    assert varied.preserve_common_prefix is True
+
+
+def test_cwb_math_index_prefix_and_scale(cwb):
+    settings = cwb.resolve_cwb_settings(
+        cwb_preset="custom",
+        consensus_type="mean",
+        alignment_method="index",
+        global_scale=1.0,
+    )
+    first = torch.tensor([[1.0, 0.0], [0.0, 1.0]])
+    second = torch.tensor([[3.0, 0.0], [0.0, 3.0]])
+    torch.testing.assert_close(
+        cwb.merge_cwb_tensors([first, second], settings),
+        torch.tensor([[2.0, 0.0], [0.0, 2.0]]),
+    )
+
+    prefix_settings = cwb.resolve_cwb_settings(
+        cwb_preset="custom",
+        consensus_type="mean",
+        alignment_method="index",
+        global_scale=2.0,
+        preserve_common_prefix=True,
+    )
+    prefixed = cwb.merge_cwb_tensors(
+        [torch.tensor([[9.0, 9.0], [1.0, 0.0]]),
+         torch.tensor([[9.0, 9.0], [3.0, 0.0]])],
+        prefix_settings,
+    )
+    torch.testing.assert_close(prefixed[0], torch.tensor([9.0, 9.0]))
+    torch.testing.assert_close(prefixed[1], torch.tensor([4.0, 0.0]))
+
+
+def test_similarity_alignment_reorders_matching_rows(cwb):
+    settings = cwb.resolve_cwb_settings(
+        cwb_preset="custom",
+        consensus_type="mean",
+        alignment_method="similarity",
+        alignment_threshold=0.5,
+    )
+    reference = torch.tensor([[1.0, 0.0], [0.0, 1.0]])
+    reversed_source = torch.tensor([[0.0, 2.0], [2.0, 0.0]])
+    torch.testing.assert_close(
+        cwb.merge_cwb_tensors([reference, reversed_source], settings),
+        torch.tensor([[1.5, 0.0], [0.0, 1.5]]),
+    )
+
+    scores = torch.ones((2, 2))
+    biased = cwb._position_biased_scores(scores, 1.0)
+    assert biased[0, 0] > biased[0, 1]
+
+
+def test_fixed_coordinate_merge_never_reorders_model_rows(cwb):
+    settings = cwb.resolve_cwb_settings(
+        cwb_preset="custom",
+        consensus_type="mean",
+        alignment_method="similarity",
+        alignment_threshold=0.5,
+    )
+    reference = torch.tensor([[1.0, 0.0], [0.0, 1.0]])
+    reversed_source = torch.tensor([[0.0, 2.0], [2.0, 0.0]])
+    expected = torch.stack([
+        cwb.merge_consensus_group(
+            torch.stack([reference[row], reversed_source[row]]), settings
+        )
+        for row in range(reference.shape[0])
+    ])
+    torch.testing.assert_close(
+        cwb.merge_cwb_tensors(
+            [reference, reversed_source],
+            settings,
+            allow_similarity_alignment=False,
+        ),
+        expected,
+    )
+
+
+def test_lora_similarity_alignment_pairs_a_rows_with_b_columns(cwb):
+    settings = cwb.resolve_cwb_settings(
+        cwb_preset="custom",
+        consensus_type="mean",
+        alignment_method="similarity",
+        alignment_threshold=0.5,
+    )
+    reference_down = torch.tensor([[1.0, 0.0], [0.0, 1.0]])
+    reference_up = torch.tensor([[2.0, 0.0], [0.0, 3.0]])
+    source_down = torch.tensor([[0.0, 1.0], [-1.0, 0.0]])
+    source_up = torch.tensor([[0.0, -2.0], [3.0, 0.0]])
+
+    merged_down, merged_up = cwb.merge_cwb_lora_pairs(
+        [reference_down, source_down],
+        [reference_up, source_up],
+        settings,
+        reference_index=0,
+    )
+    torch.testing.assert_close(merged_down, reference_down)
+    torch.testing.assert_close(merged_up, reference_up)
+
+
+def test_lora_krea_shape_scores_only_rank_components(monkeypatch, cwb):
+    rank = 256
+    output_features = 36864
+    down = torch.ones((rank, 2))
+    up = torch.ones((output_features, rank))
+    matrix_shapes = []
+
+    def bounded_mm(left, right):
+        matrix_shapes.append((left.shape, right.shape))
+        return torch.eye(left.shape[0], right.shape[1], dtype=left.dtype)
+
+    monkeypatch.setattr(cwb.torch, "mm", bounded_mm)
+    monkeypatch.setattr(
+        cwb,
+        "merge_consensus_group",
+        lambda stacked, settings, **kwargs: stacked[0].clone(),
+    )
+    settings = cwb.resolve_cwb_settings(
+        cwb_preset="custom",
+        alignment_method="similarity",
+        alignment_threshold=0.5,
+    )
+    merged_down, merged_up = cwb.merge_cwb_lora_pairs(
+        [down, down], [up, up], settings, reference_index=0
+    )
+
+    assert merged_down.shape == down.shape
+    assert merged_up.shape == up.shape
+    assert matrix_shapes
+    assert all(left[0] == rank and right[1] == rank for left, right in matrix_shapes)
+
+
+def test_lora_alpha_and_global_scale_apply_once_to_pair(cwb):
+    settings = cwb.resolve_cwb_settings(
+        cwb_preset="custom",
+        consensus_type="mean",
+        alignment_method="index",
+        global_scale=3.0,
+    )
+    down = torch.ones((1, 1))
+    up = torch.ones((1, 1))
+    merged_down, merged_up, rank = cwb._merge_lora_pair_to_cpu(
+        [(0, down, up, 2.0), (1, down, up, 2.0)],
+        settings,
+        "cpu",
+        torch.float32,
+    )
+    assert rank == 1
+    torch.testing.assert_close(merged_down, torch.ones((1, 1)))
+    torch.testing.assert_close(merged_up, torch.full((1, 1), 6.0))
+
+
+def test_lora_pair_alignment_supports_convolution_factors(cwb):
+    settings = cwb.resolve_cwb_settings(
+        cwb_preset="custom",
+        consensus_type="mean",
+        alignment_method="index",
+    )
+    down = torch.arange(6, dtype=torch.float32).reshape(2, 3, 1, 1)
+    up = torch.arange(8, dtype=torch.float32).reshape(4, 2, 1, 1)
+    merged_down, merged_up = cwb.merge_cwb_lora_pairs(
+        [down, down], [up, up], settings, reference_index=0
+    )
+    torch.testing.assert_close(merged_down, down)
+    torch.testing.assert_close(merged_up, up)
+
+
+def test_lora_cuda_oom_retries_current_pair_on_cpu(monkeypatch, caplog, cwb):
+    settings = cwb.resolve_cwb_settings(
+        cwb_preset="custom",
+        consensus_type="mean",
+        alignment_method="index",
+    )
+    original_to_compute = cwb._to_compute
+    attempted_devices = []
+
+    def fail_cuda(tensor, device):
+        attempted_devices.append(device)
+        if str(device).startswith("cuda"):
+            raise torch.OutOfMemoryError("injected allocation failure")
+        return original_to_compute(tensor, device)
+
+    monkeypatch.setattr(cwb, "_to_compute", fail_cuda)
+    monkeypatch.setattr(cwb, "_release_failed_cuda_operation", lambda: None)
+    down = torch.ones((1, 2))
+    up = torch.ones((2, 1))
+    with caplog.at_level("WARNING"):
+        merged_down, merged_up, rank = cwb._merge_lora_pair_to_cpu(
+            [(0, down, up, 1.0), (1, down, up, 1.0)],
+            settings,
+            "cuda",
+            torch.float32,
+            operation_label="diffusion_model.foo",
+        )
+
+    assert rank == 1
+    torch.testing.assert_close(merged_down, down)
+    torch.testing.assert_close(merged_up, up)
+    assert attempted_devices[0] == "cuda"
+    assert "cpu" in attempted_devices
+    assert "retrying this layer on CPU" in caplog.text
+    assert "diffusion_model.foo" in caplog.text
+
+
+def test_norm_rescale_and_dsc_bandpass_are_finite(cwb):
+    rescale = cwb.resolve_cwb_settings(
+        cwb_preset="custom",
+        consensus_type="mean",
+        rescale_norm=True,
+    )
+    merged = cwb.merge_consensus_group(
+        torch.tensor([[2.0, 0.0], [0.0, 2.0]]), rescale
+    )
+    assert torch.linalg.vector_norm(merged).item() == pytest.approx(2.0)
+
+    dsc = cwb.resolve_cwb_settings(
+        cwb_preset="custom",
+        consensus_type="median",
+        diversity_beta=1.5,
+        dynamic_similarity_contrast=True,
+        soft_comfort_bandpass=True,
+    )
+    result = cwb.merge_consensus_group(
+        torch.tensor([[1.0, 0.0], [0.8, 0.2], [0.0, 1.0]]), dsc
+    )
+    assert torch.isfinite(result).all()
+
+
+def test_all_ten_schemas_and_lora_switch_contract(cwb):
+    assert len(cwb.CWB_MERGER_NODES) == 10
+    assert len({node.NODE_ID for node in cwb.CWB_MERGER_NODES}) == 10
+    for node in cwb.CWB_MERGER_NODES:
+        schema = node.define_schema()
+        ids = [value.id for value in schema.inputs]
+        assert ids[:3] == ["execution_mode", "model_a", "model_b"]
+        if node.INPUT_COUNT == 3:
+            assert ids[3] == "model_c"
+        if node.LORA_MODE:
+            assert schema.inputs[-1].id == "include_1d_diffs"
+            assert schema.inputs[-1].default is False
+        else:
+            assert "include_1d_diffs" not in ids
+
+
+def test_streaming_dtype_nonfloat_and_secondary_preservation(
+    monkeypatch, tmp_path, cwb
+):
+    a = tmp_path / "a.safetensors"
+    b = tmp_path / "b.safetensors"
+    save_file({
+        "shared": torch.tensor([[1.0, 0.0], [0.0, 1.0]], dtype=torch.float32),
+        "only_a": torch.tensor([5.0, 6.0], dtype=torch.float16),
+        "metadata_tensor": torch.tensor([1, 2], dtype=torch.int64),
+    }, str(a), metadata={"source": "A"})
+    save_file({
+        "shared": torch.tensor([[3.0, 0.0], [0.0, 3.0]], dtype=torch.float16),
+        "extra": torch.ones((2, 2)),
+        "metadata_tensor": torch.tensor([9, 9], dtype=torch.int64),
+    }, str(b))
+    paths = {"a": str(a), "b": str(b)}
+    _patch_io(monkeypatch, cwb, tmp_path, paths)
+
+    result = cwb.ConsensusMergerLogic.execute(
+        ["a", "b"], "diffusion_models", _params("anchored")
+    )
+    tensors = load_file(str(_result_path(tmp_path, "diffusion_models", result)))
+    assert set(tensors) == {"shared", "only_a", "extra", "metadata_tensor"}
+    torch.testing.assert_close(tensors["shared"], torch.tensor([[2.0, 0.0], [0.0, 2.0]]))
+    assert tensors["shared"].dtype == torch.float32
+    torch.testing.assert_close(tensors["only_a"], torch.tensor([5.0, 6.0], dtype=torch.float16))
+    torch.testing.assert_close(tensors["metadata_tensor"], torch.tensor([1, 2]))
+    torch.testing.assert_close(tensors["extra"], torch.ones((2, 2)))
+
+    overridden = cwb.ConsensusMergerLogic.execute(
+        ["a", "b"],
+        "diffusion_models",
+        _params("anchored_override", override_dtype=True),
+    )
+    overridden_tensors = load_file(
+        str(_result_path(tmp_path, "diffusion_models", overridden))
+    )
+    assert overridden_tensors["shared"].dtype == torch.float16
+    assert overridden_tensors["metadata_tensor"].dtype == torch.int64
+
+
+def test_failed_merge_preserves_existing_output_and_removes_temporary_file(
+    monkeypatch, tmp_path, cwb
+):
+    a = tmp_path / "atomic_a.safetensors"
+    b = tmp_path / "atomic_b.safetensors"
+    output = tmp_path / "diffusion_models" / "atomic_output.safetensors"
+    output.parent.mkdir(parents=True)
+    save_file({"layer": torch.ones((2, 2))}, str(a))
+    save_file({"layer": torch.full((2, 2), 2.0)}, str(b))
+    save_file({"existing": torch.tensor([7.0])}, str(output))
+    paths = {"a": str(a), "b": str(b)}
+    _patch_io(monkeypatch, cwb, tmp_path, paths)
+
+    def fail_merge(*args, **kwargs):
+        raise RuntimeError("injected CWB failure")
+
+    monkeypatch.setattr(cwb, "merge_cwb_tensors", fail_merge)
+    with pytest.raises(RuntimeError, match="injected CWB failure"):
+        cwb.ConsensusMergerLogic.execute(
+            ["a", "b"], "diffusion_models", _params("atomic_output")
+        )
+
+    existing = load_file(str(output))
+    assert set(existing) == {"existing"}
+    torch.testing.assert_close(existing["existing"], torch.tensor([7.0]))
+    assert not list(output.parent.glob(".atomic_output.safetensors.*.tmp"))
+
+
+def test_embedding_union_uses_longest_first_dimension(monkeypatch, tmp_path, cwb):
+    a = tmp_path / "embed_a.safetensors"
+    b = tmp_path / "embed_b.safetensors"
+    save_file({"emb": torch.tensor([[1.0, 0.0], [0.0, 1.0]])}, str(a))
+    save_file({
+        "emb": torch.tensor([[3.0, 0.0], [0.0, 3.0], [4.0, 4.0]]),
+        "secondary_only": torch.tensor([[7.0, 0.0]]),
+    }, str(b))
+    paths = {"a": str(a), "b": str(b)}
+    _patch_io(monkeypatch, cwb, tmp_path, paths)
+    result = cwb.ConsensusMergerLogic.execute(
+        ["a", "b"],
+        "embeddings",
+        _params("embedding_union"),
+        embedding_union=True,
+    )
+    tensors = load_file(str(_result_path(tmp_path, "embeddings", result)))
+    assert tensors["emb"].shape == (3, 2)
+    torch.testing.assert_close(tensors["emb"][:2], torch.tensor([[2.0, 0.0], [0.0, 2.0]]))
+    torch.testing.assert_close(tensors["emb"][2], torch.tensor([4.0, 4.0]))
+    torch.testing.assert_close(tensors["secondary_only"], torch.tensor([[7.0, 0.0]]))
+
+
+def test_three_input_streaming_merge(monkeypatch, tmp_path, cwb):
+    paths = {}
+    for name, value in (("a", 1.0), ("b", 3.0), ("c", 5.0)):
+        path = tmp_path / f"three_{name}.safetensors"
+        save_file({"layer": torch.tensor([[value, 0.0]])}, str(path))
+        paths[name] = str(path)
+    _patch_io(monkeypatch, cwb, tmp_path, paths)
+    result = cwb.ConsensusMergerLogic.execute(
+        ["a", "b", "c"], "diffusion_models", _params("three_inputs")
+    )
+    tensor = load_file(str(_result_path(tmp_path, "diffusion_models", result)))["layer"]
+    torch.testing.assert_close(tensor, torch.tensor([[3.0, 0.0]]))
+
+
+def test_two_input_preserves_secondary_only_tensor_exactly(monkeypatch, tmp_path, cwb):
+    a = tmp_path / "secondary_a.safetensors"
+    b = tmp_path / "secondary_b.safetensors"
+    save_file({"shared": torch.tensor([1.0])}, str(a))
+    save_file({
+        "shared": torch.tensor([1.0]),
+        "secondary": torch.tensor([2.0, 3.0], dtype=torch.float32),
+    }, str(b))
+    _patch_io(monkeypatch, cwb, tmp_path, {"a": str(a), "b": str(b)})
+
+    result = cwb.ConsensusMergerLogic.execute(
+        ["a", "b"],
+        "diffusion_models",
+        _params(
+            "secondary_exact",
+            global_scale=2.0,
+            override_dtype=True,
+            save_dtype="fp16",
+        ),
+    )
+    tensor = load_file(str(_result_path(tmp_path, "diffusion_models", result)))["secondary"]
+    torch.testing.assert_close(tensor, torch.tensor([2.0, 3.0]))
+    assert tensor.dtype == torch.float32
+
+
+def test_three_input_merges_available_secondary_sources(monkeypatch, tmp_path, cwb):
+    a = tmp_path / "union_a.safetensors"
+    b = tmp_path / "union_b.safetensors"
+    c = tmp_path / "union_c.safetensors"
+    save_file({"shared": torch.tensor([1.0])}, str(a))
+    save_file({
+        "shared": torch.tensor([1.0]),
+        "secondary_shared": torch.tensor([2.0]),
+        "b_only": torch.tensor([7.0]),
+    }, str(b))
+    save_file({
+        "shared": torch.tensor([1.0]),
+        "secondary_shared": torch.tensor([4.0]),
+        "c_only": torch.tensor([9.0]),
+    }, str(c))
+    _patch_io(monkeypatch, cwb, tmp_path, {"a": str(a), "b": str(b), "c": str(c)})
+
+    result = cwb.ConsensusMergerLogic.execute(
+        ["a", "b", "c"], "diffusion_models", _params("secondary_union")
+    )
+    tensors = load_file(str(_result_path(tmp_path, "diffusion_models", result)))
+    torch.testing.assert_close(tensors["secondary_shared"], torch.tensor([3.0]))
+    torch.testing.assert_close(tensors["b_only"], torch.tensor([7.0]))
+    torch.testing.assert_close(tensors["c_only"], torch.tensor([9.0]))
+
+
+def test_secondary_shape_conflict_skip_preserves_earliest_source(monkeypatch, tmp_path, cwb):
+    a = tmp_path / "shape_a.safetensors"
+    b = tmp_path / "shape_b.safetensors"
+    c = tmp_path / "shape_c.safetensors"
+    save_file({"shared": torch.tensor([1.0])}, str(a))
+    save_file({"secondary": torch.tensor([2.0, 3.0])}, str(b))
+    save_file({"secondary": torch.tensor([[8.0, 9.0]])}, str(c))
+    _patch_io(monkeypatch, cwb, tmp_path, {"a": str(a), "b": str(b), "c": str(c)})
+
+    result = cwb.ConsensusMergerLogic.execute(
+        ["a", "b", "c"],
+        "diffusion_models",
+        _params("secondary_shape_skip", mismatch_mode="skip"),
+    )
+    tensor = load_file(str(_result_path(tmp_path, "diffusion_models", result)))["secondary"]
+    torch.testing.assert_close(tensor, torch.tensor([2.0, 3.0]))
+
+
+def test_secondary_only_filters_and_low_bit_preservation(monkeypatch, tmp_path, cwb):
+    a = tmp_path / "filter_a.safetensors"
+    b = tmp_path / "filter_b.safetensors"
+    save_file({"shared": torch.tensor([1.0])}, str(a))
+    save_file({
+        "secondary.keep": torch.tensor([4, 5], dtype=torch.uint8),
+        "secondary.drop": torch.tensor([6.0]),
+    }, str(b))
+    _patch_io(monkeypatch, cwb, tmp_path, {"a": str(a), "b": str(b)})
+
+    result = cwb.ConsensusMergerLogic.execute(
+        ["a", "b"],
+        "diffusion_models",
+        _params("secondary_filters", discard_patterns=r"secondary\.drop"),
+    )
+    tensors = load_file(str(_result_path(tmp_path, "diffusion_models", result)))
+    assert "secondary.drop" not in tensors
+    torch.testing.assert_close(
+        tensors["secondary.keep"], torch.tensor([4, 5], dtype=torch.uint8)
+    )
+
+
+def test_lora_cross_format_companion_group_preserves_model_a_canonically(
+    monkeypatch, tmp_path, cwb
+):
+    a = tmp_path / "lora_a.safetensors"
+    b = tmp_path / "lora_b.safetensors"
+    save_file({
+        "diffusion_model.foo.lora_A.weight": torch.tensor([[1.0, 2.0]], dtype=torch.float32),
+        "diffusion_model.foo.lora_B.weight": torch.tensor([[1.0], [2.0]], dtype=torch.float32),
+        "diffusion_model.foo.dora_scale": torch.tensor([1.0, 1.0]),
+    }, str(a))
+    save_file({
+        "lora_unet_foo.lora_down.weight": torch.tensor([[3.0, 4.0], [5.0, 6.0]]),
+        "lora_unet_foo.lora_up.weight": torch.tensor([[3.0, 5.0], [4.0, 6.0]]),
+        "lora_unet_secondary.lora_down.weight": torch.ones((1, 2)),
+        "lora_unet_secondary.lora_up.weight": torch.ones((2, 1)),
+    }, str(b))
+    paths = {"a": str(a), "b": str(b)}
+    _patch_io(monkeypatch, cwb, tmp_path, paths)
+    result = cwb.ConsensusMergerLogic.execute(
+        ["a", "b"], "loras", _params("lora_cross_format"), lora_mode=True
+    )
+    tensors = load_file(str(_result_path(tmp_path, "loras", result)))
+    assert set(tensors) == {
+        "diffusion_model.foo.lora_A.weight",
+        "diffusion_model.foo.lora_B.weight",
+        "diffusion_model.foo.dora_scale",
+        "lora_unet_secondary.lora_A.weight",
+        "lora_unet_secondary.lora_B.weight",
+    }
+    assert tensors["diffusion_model.foo.lora_A.weight"].shape == (1, 2)
+    assert tensors["diffusion_model.foo.lora_B.weight"].shape == (2, 1)
+    assert tensors["diffusion_model.foo.lora_A.weight"].dtype == torch.float32
+    torch.testing.assert_close(
+        tensors["diffusion_model.foo.dora_scale"], torch.tensor([1.0, 1.0])
+    )
+    torch.testing.assert_close(
+        tensors["lora_unet_secondary.lora_A.weight"], torch.ones((1, 2))
+    )
+    torch.testing.assert_close(
+        tensors["lora_unet_secondary.lora_B.weight"], torch.ones((2, 1))
+    )
+
+
+def test_lora_secondary_only_pair_is_preserved_without_scaling(
+    monkeypatch, tmp_path, cwb
+):
+    a = tmp_path / "lora_secondary_a.safetensors"
+    b = tmp_path / "lora_secondary_b.safetensors"
+    save_file({
+        "diffusion_model.base.diff": torch.tensor([[1.0]]),
+    }, str(a))
+    save_file({
+        "transformer.extra.lora_down.weight": torch.tensor([[2.0, 3.0]]),
+        "transformer.extra.lora_up.weight": torch.tensor([[4.0], [5.0]]),
+        "transformer.extra.alpha": torch.tensor(1.0),
+    }, str(b))
+    _patch_io(monkeypatch, cwb, tmp_path, {"a": str(a), "b": str(b)})
+
+    result = cwb.ConsensusMergerLogic.execute(
+        ["a", "b"],
+        "loras",
+        _params(
+            "lora_secondary_exact",
+            global_scale=2.0,
+            override_dtype=True,
+            save_dtype="fp16",
+        ),
+        lora_mode=True,
+    )
+    tensors = load_file(str(_result_path(tmp_path, "loras", result)))
+    torch.testing.assert_close(
+        tensors["diffusion_model.extra.lora_A.weight"],
+        torch.tensor([[2.0, 3.0]]),
+    )
+    torch.testing.assert_close(
+        tensors["diffusion_model.extra.lora_B.weight"],
+        torch.tensor([[4.0], [5.0]]),
+    )
+    assert tensors["diffusion_model.extra.lora_A.weight"].dtype == torch.float32
+    assert tensors["diffusion_model.extra.alpha"].item() == pytest.approx(1.0)
+
+
+def test_lora_three_input_merges_b_and_c_group_without_a(monkeypatch, tmp_path, cwb):
+    a = tmp_path / "lora_union_a.safetensors"
+    b = tmp_path / "lora_union_b.safetensors"
+    c = tmp_path / "lora_union_c.safetensors"
+    save_file({"diffusion_model.base.diff": torch.tensor([[1.0]])}, str(a))
+    save_file({
+        "diffusion_model.extra.lora_A.weight": torch.full((1, 2), 1.0),
+        "diffusion_model.extra.lora_B.weight": torch.full((2, 1), 1.0),
+    }, str(b))
+    save_file({
+        "transformer.extra.lora_down.weight": torch.full((1, 2), 3.0),
+        "transformer.extra.lora_up.weight": torch.full((2, 1), 3.0),
+    }, str(c))
+    _patch_io(monkeypatch, cwb, tmp_path, {"a": str(a), "b": str(b), "c": str(c)})
+
+    result = cwb.ConsensusMergerLogic.execute(
+        ["a", "b", "c"], "loras", _params("lora_secondary_union"), lora_mode=True
+    )
+    tensors = load_file(str(_result_path(tmp_path, "loras", result)))
+    torch.testing.assert_close(
+        tensors["diffusion_model.extra.lora_A.weight"], torch.full((1, 2), 2.0)
+    )
+    torch.testing.assert_close(
+        tensors["diffusion_model.extra.lora_B.weight"], torch.full((2, 1), 2.0)
+    )
+
+
+def test_lora_secondary_direct_and_companion_groups_are_atomic(
+    monkeypatch, tmp_path, cwb
+):
+    a = tmp_path / "lora_atomic_a.safetensors"
+    b = tmp_path / "lora_atomic_b.safetensors"
+    save_file({"diffusion_model.base.diff": torch.tensor([[1.0]])}, str(a))
+    save_file({
+        "diffusion_model.norm.diff": torch.tensor([2.0, 3.0], dtype=torch.bfloat16),
+        "diffusion_model.extra.lora_A.weight": torch.tensor([[4.0, 5.0]]),
+        "diffusion_model.extra.lora_B.weight": torch.tensor([[6.0], [7.0]]),
+        "diffusion_model.extra.dora_scale": torch.tensor([8.0, 9.0]),
+    }, str(b))
+    _patch_io(monkeypatch, cwb, tmp_path, {"a": str(a), "b": str(b)})
+
+    result = cwb.ConsensusMergerLogic.execute(
+        ["a", "b"],
+        "loras",
+        _params("lora_secondary_atomic", global_scale=3.0),
+        lora_mode=True,
+    )
+    tensors = load_file(str(_result_path(tmp_path, "loras", result)))
+    torch.testing.assert_close(
+        tensors["diffusion_model.norm.diff"],
+        torch.tensor([2.0, 3.0], dtype=torch.bfloat16),
+    )
+    assert tensors["diffusion_model.norm.diff"].dtype == torch.bfloat16
+    torch.testing.assert_close(
+        tensors["diffusion_model.extra.lora_A.weight"], torch.tensor([[4.0, 5.0]])
+    )
+    torch.testing.assert_close(
+        tensors["diffusion_model.extra.lora_B.weight"], torch.tensor([[6.0], [7.0]])
+    )
+    torch.testing.assert_close(
+        tensors["diffusion_model.extra.dora_scale"], torch.tensor([8.0, 9.0])
+    )
+
+
+def test_lora_rejects_duplicate_normalized_cores_in_secondary_input(cwb):
+    with pytest.raises(ValueError, match="same logical layer 'foo'.*input 2"):
+        cwb._secondary_lora_map(
+            {
+                "diffusion_model.foo": {},
+                "transformer.foo": {},
+            },
+            input_index=1,
+        )
+
+
+def test_lora_peft_prefix_matching_and_existing_alpha(monkeypatch, tmp_path, cwb):
+    a = tmp_path / "peft_a.safetensors"
+    b = tmp_path / "peft_b.safetensors"
+    save_file({
+        "base_model.model.diffusion_model.foo.lora_A.weight": torch.ones((1, 2)),
+        "base_model.model.diffusion_model.foo.lora_B.weight": torch.ones((2, 1)),
+        "base_model.model.diffusion_model.foo.alpha": torch.tensor(1.0),
+    }, str(a))
+    save_file({
+        "diffusion_model.foo.lora_down.weight": torch.ones((2, 2)),
+        "diffusion_model.foo.lora_up.weight": torch.ones((2, 2)),
+        "diffusion_model.foo.alpha": torch.tensor(2.0),
+    }, str(b))
+    paths = {"a": str(a), "b": str(b)}
+    _patch_io(monkeypatch, cwb, tmp_path, paths)
+    result = cwb.ConsensusMergerLogic.execute(
+        ["a", "b"], "loras", _params("peft_prefix"), lora_mode=True
+    )
+    tensors = load_file(str(_result_path(tmp_path, "loras", result)))
+    assert set(tensors) == {
+        "diffusion_model.foo.lora_A.weight",
+        "diffusion_model.foo.lora_B.weight",
+        "diffusion_model.foo.alpha",
+    }
+    assert tensors["diffusion_model.foo.alpha"].item() == pytest.approx(2.0)
+
+
+def test_lora_mochi_inputs_emit_preferred_canonical_output(
+    monkeypatch, tmp_path, cwb
+):
+    a = tmp_path / "mochi_a.safetensors"
+    b = tmp_path / "mochi_b.safetensors"
+    for path, value in ((a, 1.0), (b, 3.0)):
+        save_file({
+            "diffusion_model.foo.lora_A": torch.full((1, 2), value),
+            "diffusion_model.foo.lora_B": torch.full((2, 1), value),
+            "diffusion_model.foo.alpha": torch.tensor(1.0),
+        }, str(path))
+    paths = {"a": str(a), "b": str(b)}
+    _patch_io(monkeypatch, cwb, tmp_path, paths)
+
+    result = cwb.ConsensusMergerLogic.execute(
+        ["a", "b"], "loras", _params("mochi_canonical"), lora_mode=True
+    )
+    tensors = load_file(str(_result_path(tmp_path, "loras", result)))
+
+    assert set(tensors) == {
+        "diffusion_model.foo.lora_A.weight",
+        "diffusion_model.foo.lora_B.weight",
+        "diffusion_model.foo.alpha",
+    }
+
+
+def test_lora_1d_direct_switch_is_default_fallback_and_fp32(
+    monkeypatch, tmp_path, cwb
+):
+    a = tmp_path / "direct_a.safetensors"
+    b = tmp_path / "direct_b.safetensors"
+    save_file({"diffusion_model.norm.diff": torch.tensor([1.0, 2.0], dtype=torch.bfloat16)}, str(a))
+    save_file({"diffusion_model.norm.diff": torch.tensor([3.0, 4.0], dtype=torch.bfloat16)}, str(b))
+    paths = {"a": str(a), "b": str(b)}
+    _patch_io(monkeypatch, cwb, tmp_path, paths)
+
+    default = cwb.ConsensusMergerLogic.execute(
+        ["a", "b"], "loras", _params("direct_default"), lora_mode=True
+    )
+    default_tensor = load_file(str(_result_path(tmp_path, "loras", default)))[
+        "diffusion_model.norm.diff"
+    ]
+    torch.testing.assert_close(default_tensor, torch.tensor([1.0, 2.0], dtype=torch.bfloat16))
+    assert default_tensor.dtype == torch.bfloat16
+
+    enabled = cwb.ConsensusMergerLogic.execute(
+        ["a", "b"],
+        "loras",
+        _params("direct_enabled", include_1d_diffs=True, override_dtype=True),
+        lora_mode=True,
+    )
+    enabled_tensor = load_file(str(_result_path(tmp_path, "loras", enabled)))[
+        "diffusion_model.norm.diff"
+    ]
+    torch.testing.assert_close(enabled_tensor, torch.tensor([2.0, 3.0]))
+    assert enabled_tensor.dtype == torch.float32
+
+
+def test_quantized_marker_errors_before_output(monkeypatch, tmp_path, cwb):
+    a = tmp_path / "quant_a.safetensors"
+    b = tmp_path / "quant_b.safetensors"
+    save_file({
+        "layer.weight": torch.ones((2, 2)),
+        "layer.comfy_quant": torch.tensor([1], dtype=torch.uint8),
+    }, str(a))
+    save_file({"layer.weight": torch.ones((2, 2))}, str(b))
+    paths = {"a": str(a), "b": str(b)}
+    _patch_io(monkeypatch, cwb, tmp_path, paths)
+    with pytest.raises(ValueError, match="ComfyUI quantization metadata"):
+        cwb.ConsensusMergerLogic.execute(
+            ["a", "b"], "diffusion_models", _params("must_not_exist")
+        )
+    assert not (tmp_path / "diffusion_models" / "must_not_exist.safetensors").exists()
+
+
+def test_isolated_low_bit_preserves_anchored_tensor(monkeypatch, tmp_path, cwb):
+    a = tmp_path / "guard_a.safetensors"
+    b = tmp_path / "guard_b.safetensors"
+    save_file({"layer": torch.tensor([1.0, 2.0])}, str(a))
+    save_file({"layer": torch.tensor([8, 9], dtype=torch.uint8)}, str(b))
+    paths = {"a": str(a), "b": str(b)}
+    _patch_io(monkeypatch, cwb, tmp_path, paths)
+    result = cwb.ConsensusMergerLogic.execute(
+        ["a", "b"], "diffusion_models", _params("guarded_generic")
+    )
+    tensor = load_file(str(_result_path(tmp_path, "diffusion_models", result)))["layer"]
+    torch.testing.assert_close(tensor, torch.tensor([1.0, 2.0]))
+    assert tensor.dtype == torch.float32
+
+
+def test_isolated_low_bit_preserves_complete_lora_layer(monkeypatch, tmp_path, cwb):
+    a = tmp_path / "guard_lora_a.safetensors"
+    b = tmp_path / "guard_lora_b.safetensors"
+    save_file({
+        "diffusion_model.foo.lora_A.weight": torch.tensor([[1.0, 2.0]]),
+        "diffusion_model.foo.lora_B.weight": torch.tensor([[3.0], [4.0]]),
+        "diffusion_model.foo.alpha": torch.tensor(1.0),
+        "diffusion_model.foo.dora_scale": torch.tensor([5.0, 6.0]),
+    }, str(a))
+    save_file({
+        "diffusion_model.foo.lora_A.weight": torch.tensor([[9.0, 9.0]]),
+        "diffusion_model.foo.lora_B.weight": torch.tensor([[9.0], [9.0]]),
+        "diffusion_model.foo.alpha": torch.tensor(1, dtype=torch.uint8),
+    }, str(b))
+    paths = {"a": str(a), "b": str(b)}
+    _patch_io(monkeypatch, cwb, tmp_path, paths)
+    result = cwb.ConsensusMergerLogic.execute(
+        ["a", "b"], "loras", _params("guarded_lora"), lora_mode=True
+    )
+    tensors = load_file(str(_result_path(tmp_path, "loras", result)))
+    torch.testing.assert_close(
+        tensors["diffusion_model.foo.lora_A.weight"], torch.tensor([[1.0, 2.0]])
+    )
+    torch.testing.assert_close(
+        tensors["diffusion_model.foo.lora_B.weight"], torch.tensor([[3.0], [4.0]])
+    )
+    assert tensors["diffusion_model.foo.alpha"].item() == pytest.approx(1.0)
+    torch.testing.assert_close(
+        tensors["diffusion_model.foo.dora_scale"], torch.tensor([5.0, 6.0])
+    )

tests/test_lora_diff_dtype_contract.py

@@ -0,0 +1,899 @@
+import importlib
+import logging
+import sys
+import types
+from pathlib import Path
+
+import pytest
+import torch
+from safetensors.torch import load_file, save_file
+
+
+REPO_ROOT = Path(__file__).resolve().parents[1]
+PACKAGE_NAME = "modelutils_contract_tests"
+
+
+def _load_module(name):
+    if PACKAGE_NAME not in sys.modules:
+        package = types.ModuleType(PACKAGE_NAME)
+        package.__path__ = [str(REPO_ROOT)]
+        sys.modules[PACKAGE_NAME] = package
+    return importlib.import_module(f"{PACKAGE_NAME}.{name}")
+
+
+@pytest.fixture(scope="module")
+def modules():
+    return _load_module("nodes.lora_resize"), _load_module("nodes.lora_merger")
+
+
+@pytest.fixture(scope="module")
+def generic_modules():
+    return _load_module("nodes.merger"), _load_module("nodes.merger_ops")
+
+
+def _patch_output(monkeypatch, module, output_dir):
+    monkeypatch.setattr(module.folder_paths, "get_folder_paths", lambda _: [str(output_dir)])
+    monkeypatch.setattr(module.folder_paths, "models_dir", str(output_dir))
+    monkeypatch.setattr(module, "prepare_for_large_operation", lambda *args, **kwargs: None)
+    monkeypatch.setattr(module, "cleanup_after_operation", lambda: None)
+
+
+COMFY_LORA_PAIR_SUFFIXES = [
+    (".lora_down.weight", ".lora_up.weight"),
+    ("_lora.down.weight", "_lora.up.weight"),
+    (".lora_A.weight", ".lora_B.weight"),
+    (".lora.down.weight", ".lora.up.weight"),
+    (".lora_A", ".lora_B"),
+    (".lora_linear_layer.down.weight", ".lora_linear_layer.up.weight"),
+    (".lora_A.default.weight", ".lora_B.default.weight"),
+]
+
+
+@pytest.mark.parametrize("down_suffix,up_suffix", COMFY_LORA_PAIR_SUFFIXES)
+def test_all_comfy_lora_pair_spellings_parse_to_canonical_keys(
+    modules, down_suffix, up_suffix
+):
+    resize, _ = modules
+    block = "diffusion_model.layer"
+    layers, passthrough = resize.parse_lora_layers([
+        f"{block}{down_suffix}",
+        f"{block}{up_suffix}",
+        f"{block}.alpha",
+    ])
+
+    assert not passthrough
+    assert layers[block]["down"] == f"{block}{down_suffix}"
+    assert layers[block]["up"] == f"{block}{up_suffix}"
+    assert resize.canonical_lora_key(block, "down") == f"{block}.lora_A.weight"
+    assert resize.canonical_lora_key(block, "up") == f"{block}.lora_B.weight"
+
+
+@pytest.mark.parametrize("down_suffix,up_suffix", COMFY_LORA_PAIR_SUFFIXES)
+def test_merge_to_model_applies_every_comfy_lora_pair_spelling(
+    monkeypatch, tmp_path, modules, down_suffix, up_suffix
+):
+    resize, _ = modules
+    _patch_output(monkeypatch, resize, tmp_path)
+    variant = COMFY_LORA_PAIR_SUFFIXES.index((down_suffix, up_suffix))
+    base = tmp_path / f"base_{variant}.safetensors"
+    adapter = tmp_path / f"adapter_{variant}.safetensors"
+    block = "diffusion_model.layer"
+    save_file({
+        "model.diffusion_model.layer.weight": torch.zeros((2, 2), dtype=torch.bfloat16),
+    }, str(base))
+    save_file({
+        f"{block}{down_suffix}": torch.tensor([[1.0, 2.0]]),
+        f"{block}{up_suffix}": torch.tensor([[3.0], [4.0]]),
+        f"{block}.alpha": torch.tensor(0.5),
+    }, str(adapter))
+
+    output = resize.merge_loras_to_model(
+        [str(adapter)], [1.0], str(base), "cpu", torch.float16,
+        f"merged_variant_{variant}", verbose=False,
+    )
+    result = load_file(output)["model.diffusion_model.layer.weight"]
+    torch.testing.assert_close(
+        result,
+        torch.tensor([[1.5, 3.0], [2.0, 4.0]]),
+    )
+    assert result.dtype == torch.float32
+
+
+def test_merge_to_model_applies_comfy_direct_norm_and_set_forms(
+    monkeypatch, tmp_path, modules
+):
+    resize, _ = modules
+    _patch_output(monkeypatch, resize, tmp_path)
+    base = tmp_path / "direct_base.safetensors"
+    adapter = tmp_path / "direct_adapter.safetensors"
+    save_file({
+        "model.diffusion_model.norm.weight": torch.zeros(2),
+        "model.diffusion_model.norm.bias": torch.zeros(2),
+        "model.diffusion_model.replace.weight": torch.zeros((2, 2)),
+    }, str(base))
+    save_file({
+        "diffusion_model.norm.w_norm": torch.tensor([1.0, 2.0]),
+        "diffusion_model.norm.b_norm": torch.tensor([3.0, 4.0]),
+        "diffusion_model.replace.set_weight": torch.full((2, 2), 7.0),
+    }, str(adapter))
+
+    output = resize.merge_loras_to_model(
+        [str(adapter)], [0.5], str(base), "cpu", torch.float16,
+        "direct_forms", verbose=False, include_1d_diffs=True,
+    )
+    result = load_file(output)
+    torch.testing.assert_close(
+        result["model.diffusion_model.norm.weight"], torch.tensor([0.5, 1.0])
+    )
+    torch.testing.assert_close(
+        result["model.diffusion_model.norm.bias"], torch.tensor([1.5, 2.0])
+    )
+    torch.testing.assert_close(
+        result["model.diffusion_model.replace.weight"], torch.full((2, 2), 7.0)
+    )
+
+
+def test_merge_to_model_uses_comfy_reshape_companion(
+    monkeypatch, tmp_path, modules
+):
+    resize, _ = modules
+    _patch_output(monkeypatch, resize, tmp_path)
+    base = tmp_path / "reshape_base.safetensors"
+    adapter = tmp_path / "reshape_adapter.safetensors"
+    save_file({
+        "model.diffusion_model.layer.weight": torch.zeros((1, 2)),
+    }, str(base))
+    save_file({
+        "diffusion_model.layer.lora_A.weight": torch.tensor([[1.0, 2.0]]),
+        "diffusion_model.layer.lora_B.weight": torch.tensor([[3.0], [4.0]]),
+        "diffusion_model.layer.reshape_weight": torch.tensor([2, 2]),
+    }, str(adapter))
+
+    output = resize.merge_loras_to_model(
+        [str(adapter)], [1.0], str(base), "cpu", torch.float16,
+        "reshape_companion", verbose=False,
+    )
+    result = load_file(output)["model.diffusion_model.layer.weight"]
+    assert result.shape == (2, 2)
+    torch.testing.assert_close(result, torch.tensor([[3.0, 6.0], [4.0, 8.0]]))
+
+
+def test_merge_to_model_reports_success_and_separates_base_only_biases(
+    monkeypatch, tmp_path, modules, capsys
+):
+    resize, _ = modules
+    _patch_output(monkeypatch, resize, tmp_path)
+    base = tmp_path / "summary_base.safetensors"
+    adapter = tmp_path / "summary_adapter.safetensors"
+    save_file({
+        "model.diffusion_model.layer.weight": torch.zeros((2, 2)),
+        "model.diffusion_model.layer.bias": torch.zeros(2),
+    }, str(base))
+    save_file({
+        "diffusion_model.layer.lora_A.weight": torch.ones((1, 2)),
+        "diffusion_model.layer.lora_B.weight": torch.ones((2, 1)),
+    }, str(adapter))
+
+    path, report = resize.merge_loras_to_model(
+        [str(adapter)], [1.0], str(base), "cpu", torch.float32,
+        "summary", verbose=True, return_report=True,
+    )
+    output = capsys.readouterr().out
+
+    assert Path(path).is_file()
+    assert report.startswith("SUCCESS: 1/1 adapter groups fully applied")
+    assert "[PATCHED]" not in report
+    assert "[APPLIED]" not in report
+    assert "L1: summary_adapter.safetensors, strength=1.0" in report
+    assert "[BASE-ONLY BIASES RETAINED] (1)" in report
+    assert "model.diffusion_model.layer.bias" in report
+    assert "SUCCESS: 1/1 groups applied" in output
+    assert "1 tensors patched, 1 base tensors not patched, 0 adapter issues" in output
+    assert "model.diffusion_model.layer.bias" not in output
+
+
+def test_success_report_stays_compact_and_console_is_summary_only(
+    monkeypatch, tmp_path, modules, capsys
+):
+    resize, _ = modules
+    _patch_output(monkeypatch, resize, tmp_path)
+    base = tmp_path / "many_success_base.safetensors"
+    adapter = tmp_path / "many_success_adapter.safetensors"
+    save_file({
+        f"model.diffusion_model.layer_{index}.weight": torch.zeros((2, 2))
+        for index in range(40)
+    }, str(base))
+    save_file({
+        f"diffusion_model.layer_{index}.diff": torch.ones((2, 2))
+        for index in range(40)
+    }, str(adapter))
+
+    _, report = resize.merge_loras_to_model(
+        [str(adapter)], [1.0], str(base), "cpu", torch.float32,
+        "many_success", verbose=True, return_report=True,
+    )
+    console = capsys.readouterr().out
+
+    assert report.startswith("SUCCESS: 40/40")
+    assert "layer_0.weight" not in report
+    assert "ADAPTER GROUP ISSUES\n- None" in report
+    assert len(report) < 1000
+    assert max(map(len, report.splitlines())) < 160
+    assert "layer_0.weight" not in console
+    assert len(console.splitlines()) <= 9
+
+
+def test_merge_to_model_report_identifies_shape_mismatch_and_unresolved_group(
+    monkeypatch, tmp_path, modules
+):
+    resize, _ = modules
+    _patch_output(monkeypatch, resize, tmp_path)
+    base = tmp_path / "diagnostic_base.safetensors"
+    adapter = tmp_path / "diagnostic_adapter.safetensors"
+    save_file({
+        "model.diffusion_model.layer.weight": torch.zeros((2, 2)),
+    }, str(base))
+    save_file({
+        "diffusion_model.layer.diff": torch.ones(3),
+        "diffusion_model.orphan.lora_A.weight": torch.ones((1, 2)),
+        "diffusion_model.orphan.lora_B.weight": torch.ones((2, 1)),
+    }, str(adapter))
+
+    _, report = resize.merge_loras_to_model(
+        [str(adapter)], [1.0], str(base), "cpu", torch.float32,
+        "diagnostic", verbose=False, include_1d_diffs=True, return_report=True,
+    )
+
+    assert report.startswith("COMPLETED WITH ERRORS: 0/2")
+    assert "[MAPPED BUT UNCHANGED] (1)" in report
+    assert "[SHAPE MISMATCH] (1)" in report
+    assert "source_shape=(3,), target_shape=(2, 2)" in report
+    assert "[UNRESOLVED] (1)" in report
+    assert "diffusion_model.orphan" in report
+    assert "no matching base tensor" in report
+
+
+def test_merge_to_model_detects_comfy_adapter_logged_failure_atomically(
+    monkeypatch, tmp_path, modules
+):
+    resize, _ = modules
+    _patch_output(monkeypatch, resize, tmp_path)
+    base = tmp_path / "logged_failure_base.safetensors"
+    adapter = tmp_path / "logged_failure_adapter.safetensors"
+    base_weight = torch.arange(4, dtype=torch.float32).reshape(2, 2)
+    save_file({"model.diffusion_model.layer.weight": base_weight}, str(base))
+    save_file({
+        "diffusion_model.layer.lora_A.weight": torch.ones((1, 2)),
+        "diffusion_model.layer.lora_B.weight": torch.ones((2, 1)),
+    }, str(adapter))
+
+    class LoggedFailureAdapter:
+        def calculate_weight(self, weight, key, *args, **kwargs):
+            weight.add_(99.0)
+            logging.error("ERROR lora %s synthetic internal failure", key)
+            return weight
+
+    class FakeLoRAAdapter:
+        @staticmethod
+        def load(*args, **kwargs):
+            return LoggedFailureAdapter()
+
+    monkeypatch.setattr(resize, "LoRAAdapter", FakeLoRAAdapter)
+    path, report = resize.merge_loras_to_model(
+        [str(adapter)], [1.0], str(base), "cpu", torch.float32,
+        "logged_failure", verbose=False, return_report=True,
+    )
+
+    torch.testing.assert_close(
+        load_file(path)["model.diffusion_model.layer.weight"], base_weight
+    )
+    assert report.startswith("COMPLETED WITH ERRORS: 0/1")
+    assert "[CALCULATION FAILURE] (1)" in report
+    assert "synthetic internal failure" in report
+    assert "[MAPPED BUT UNCHANGED] (1)" in report
+
+
+def test_merge_to_model_report_classifies_disabled_1d_as_exclusion(
+    monkeypatch, tmp_path, modules
+):
+    resize, _ = modules
+    _patch_output(monkeypatch, resize, tmp_path)
+    base = tmp_path / "disabled_1d_base.safetensors"
+    adapter = tmp_path / "disabled_1d_adapter.safetensors"
+    save_file({"model.diffusion_model.norm.weight": torch.zeros(2)}, str(base))
+    save_file({"diffusion_model.norm.diff": torch.ones(2)}, str(adapter))
+
+    path, report = resize.merge_loras_to_model(
+        [str(adapter)], [1.0], str(base), "cpu", torch.float32,
+        "disabled_1d", verbose=False, return_report=True,
+    )
+
+    torch.testing.assert_close(
+        load_file(path)["model.diffusion_model.norm.weight"], torch.zeros(2)
+    )
+    assert report.startswith("COMPLETED WITH EXCLUSIONS: 0/1")
+    assert "[1D DISABLED] (1)" in report
+    assert "source=diffusion_model.norm.diff" in report
+    assert "include_1d_diffs is disabled" in report
+
+
+def test_merge_to_model_report_marks_partially_applied_group(
+    monkeypatch, tmp_path, modules
+):
+    resize, _ = modules
+    _patch_output(monkeypatch, resize, tmp_path)
+    base = tmp_path / "partial_base.safetensors"
+    adapter = tmp_path / "partial_adapter.safetensors"
+    save_file({
+        "model.diffusion_model.layer.weight": torch.zeros((2, 2)),
+        "model.diffusion_model.layer.bias": torch.zeros(2),
+    }, str(base))
+    save_file({
+        "diffusion_model.layer.lora_A.weight": torch.ones((1, 2)),
+        "diffusion_model.layer.lora_B.weight": torch.ones((2, 1)),
+        "diffusion_model.layer.diff_b": torch.ones(3),
+    }, str(adapter))
+
+    path, report = resize.merge_loras_to_model(
+        [str(adapter)], [1.0], str(base), "cpu", torch.float32,
+        "partial", verbose=False, include_1d_diffs=True, return_report=True,
+    )
+    result = load_file(path)
+
+    torch.testing.assert_close(
+        result["model.diffusion_model.layer.weight"], torch.ones((2, 2))
+    )
+    torch.testing.assert_close(
+        result["model.diffusion_model.layer.bias"], torch.zeros(2)
+    )
+    assert report.startswith("COMPLETED WITH ERRORS: 0/1")
+    assert "[PARTIALLY APPLIED] (1)" in report
+    assert "source_shape=(3,), target_shape=(2,)" in report
+
+
+def test_merge_to_model_detects_raised_adapter_failure_atomically(
+    monkeypatch, tmp_path, modules
+):
+    resize, _ = modules
+    _patch_output(monkeypatch, resize, tmp_path)
+    base = tmp_path / "raised_failure_base.safetensors"
+    adapter = tmp_path / "raised_failure_adapter.safetensors"
+    base_weight = torch.eye(2)
+    save_file({"model.diffusion_model.layer.weight": base_weight}, str(base))
+    save_file({
+        "diffusion_model.layer.lora_A.weight": torch.ones((1, 2)),
+        "diffusion_model.layer.lora_B.weight": torch.ones((2, 1)),
+    }, str(adapter))
+
+    class RaisedFailureAdapter:
+        def calculate_weight(self, weight, key, *args, **kwargs):
+            weight.zero_()
+            raise RuntimeError("synthetic raised failure")
+
+    class FakeLoRAAdapter:
+        @staticmethod
+        def load(*args, **kwargs):
+            return RaisedFailureAdapter()
+
+    monkeypatch.setattr(resize, "LoRAAdapter", FakeLoRAAdapter)
+    path, report = resize.merge_loras_to_model(
+        [str(adapter)], [1.0], str(base), "cpu", torch.float32,
+        "raised_failure", verbose=False, return_report=True,
+    )
+
+    torch.testing.assert_close(
+        load_file(path)["model.diffusion_model.layer.weight"], base_weight
+    )
+    assert "[CALCULATION FAILURE] (1)" in report
+    assert "RuntimeError: synthetic raised failure" in report
+
+
+def test_merge_to_model_report_lists_skipped_tensor_and_pattern(
+    monkeypatch, tmp_path, modules
+):
+    resize, _ = modules
+    _patch_output(monkeypatch, resize, tmp_path)
+    base = tmp_path / "skip_base.safetensors"
+    adapter = tmp_path / "skip_adapter.safetensors"
+    save_file({
+        "model.diffusion_model.layer.weight": torch.zeros((2, 2)),
+        "model.diffusion_model.layer.bias": torch.zeros(2),
+    }, str(base))
+    save_file({
+        "diffusion_model.layer.lora_A.weight": torch.ones((1, 2)),
+        "diffusion_model.layer.lora_B.weight": torch.ones((2, 1)),
+    }, str(adapter))
+
+    path, report = resize.merge_loras_to_model(
+        [str(adapter)], [1.0], str(base), "cpu", torch.float32,
+        "skip", skip_patterns_str=r"layer\.weight$", verbose=False,
+        return_report=True,
+    )
+
+    assert "model.diffusion_model.layer.weight" not in load_file(path)
+    assert report.startswith("COMPLETED WITH EXCLUSIONS: 0/1")
+    assert "[OMITTED BY SKIP PATTERN] (1)" in report
+    assert r"pattern=layer\.weight$" in report
+    assert "[SKIPPED BY PATTERN] (1)" in report
+
+
+def test_merge_to_model_node_returns_path_blank_line_report(
+    monkeypatch, modules
+):
+    resize, _ = modules
+    monkeypatch.setattr(
+        resize.folder_paths, "get_full_path_or_raise",
+        lambda category, name: f"{category}/{name}",
+    )
+    monkeypatch.setattr(
+        resize, "merge_loras_to_model",
+        lambda **kwargs: ("saved/model.safetensors", "SUCCESS\nDETAILS"),
+    )
+
+    result = resize.LoRAMergeToModel.execute(
+        "base.safetensors", "1",
+        "one.safetensors", 1.0,
+        "None", 1.0, "None", 1.0, "None", 1.0,
+        "None", 1.0, "None", 1.0, "None", 1.0, "None", 1.0,
+        "", "merged", "fp32", "cpu", True, False, False,
+    )
+
+    assert result.result == ("saved/model.safetensors\n\nSUCCESS\nDETAILS",)
+
+
+def test_mixed_parser_scans_every_key_and_retains_unpaired(modules):
+    resize, _ = modules
+    filler = [f"metadata.tensor_{index}" for index in range(60)]
+    keys = filler + [
+        "diffusion_model.linear.lora_down.weight",
+        "diffusion_model.linear.lora_up.weight",
+        "diffusion_model.linear.alpha",
+        "diffusion_model.norm.diff",
+        "diffusion_model.block.diff_b",
+        "diffusion_model.orphan.lora_down.weight",
+        "diffusion_model.linear.dora_scale",
+    ]
+
+    info = resize.detect_lora_format(keys)
+    layers, passthrough = resize.parse_lora_layers(keys)
+
+    assert info["format"] == "mixed"
+    assert layers["diffusion_model.linear"]["down"].endswith("lora_down.weight")
+    assert layers["diffusion_model.norm"]["diff"].endswith(".diff")
+    assert layers["diffusion_model.block"]["diff_b"].endswith(".diff_b")
+    assert "diffusion_model.orphan.lora_down.weight" in passthrough
+    assert layers["diffusion_model.linear"]["dora_scale"].endswith(".dora_scale")
+
+
+def test_dtype_contract(modules):
+    resize, _ = modules
+    assert resize.select_output_dtype([torch.bfloat16], torch.float16, is_1d_diff=True) == torch.float32
+    assert resize.select_output_dtype([torch.float32, torch.bfloat16], torch.float16) == torch.float32
+    assert resize.select_output_dtype([torch.float32], torch.bfloat16, force=True) == torch.bfloat16
+
+
+def test_include_1d_switches_are_appended_and_default_off(modules, generic_modules):
+    resize, multi = modules
+    generic, _ = generic_modules
+    node_classes = [
+        generic.LoRATwoMerger,
+        generic.LoRAThreeMerger,
+        multi.LoRAMultiMerge,
+        multi.LoRAMultiMergeDARE,
+        multi.LoRAMultiMergeDAREEnhanced,
+        resize.LoRAMergeToModel,
+    ]
+
+    for node_class in node_classes:
+        final_input = node_class.define_schema().inputs[-1]
+        assert final_input.id == "include_1d_diffs"
+        assert final_input.default is False
+
+    assert len(resize.LoRAMergeToModel.define_schema().outputs) == 1
+
+
+def test_resize_preserves_mixed_direct_auxiliary_and_fp32(monkeypatch, tmp_path, modules):
+    resize, _ = modules
+    _patch_output(monkeypatch, resize, tmp_path)
+    source = tmp_path / "mixed.safetensors"
+    save_file({
+        "diffusion_model.linear.lora_down.weight": torch.arange(8, dtype=torch.float32).reshape(2, 4),
+        "diffusion_model.linear.lora_up.weight": torch.arange(8, dtype=torch.float32).reshape(4, 2),
+        "diffusion_model.linear.alpha": torch.tensor(2.0, dtype=torch.float32),
+        "diffusion_model.norm.diff": torch.tensor([0.125, -0.25], dtype=torch.bfloat16),
+        "diffusion_model.scale.diff": torch.tensor(0.5, dtype=torch.bfloat16),
+        "diffusion_model.lin.diff": torch.full((2, 2), 1e-8, dtype=torch.float32),
+        "diffusion_model.linear.dora_scale": torch.ones(4, dtype=torch.float32),
+        "diffusion_model.orphan.lora_down.weight": torch.ones((1, 2), dtype=torch.bfloat16),
+    }, str(source))
+
+    output = resize.resize_lora_file(
+        str(source), 1, None, None, "cpu", torch.float16, "resized", verbose=False
+    )
+    tensors = load_file(output)
+
+    assert tensors["diffusion_model.linear.lora_A.weight"].shape[0] == 2
+    assert tensors["diffusion_model.linear.lora_A.weight"].dtype == torch.float32
+    assert tensors["diffusion_model.linear.lora_B.weight"].dtype == torch.float32
+    assert tensors["diffusion_model.linear.alpha"].dtype == torch.float32
+    assert tensors["diffusion_model.norm.diff"].dtype == torch.float32
+    assert tensors["diffusion_model.scale.diff"].dtype == torch.float16
+    assert tensors["diffusion_model.lin.diff"].dtype == torch.float32
+    assert tensors["diffusion_model.linear.dora_scale"].dtype == torch.float32
+    assert tensors["diffusion_model.orphan.lora_down.weight"].dtype == torch.float16
+
+    pure_source = tmp_path / "pure_diff.safetensors"
+    save_file({
+        "diffusion_model.pure.diff": torch.ones((2, 2), dtype=torch.bfloat16),
+        "diffusion_model.pure_norm.diff": torch.ones(2, dtype=torch.bfloat16),
+    }, str(pure_source))
+    pure_output = resize.resize_lora_file(
+        str(pure_source), 1, None, None, "cpu", torch.float16, "pure_resized", verbose=False
+    )
+    pure_tensors = load_file(pure_output)
+    assert set(pure_tensors) == {"diffusion_model.pure.diff", "diffusion_model.pure_norm.diff"}
+    assert pure_tensors["diffusion_model.pure.diff"].dtype == torch.float16
+    assert pure_tensors["diffusion_model.pure_norm.diff"].dtype == torch.float32
+
+
+def test_resize_normalizes_mochi_pair_to_preferred_output(
+    monkeypatch, tmp_path, modules
+):
+    resize, _ = modules
+    _patch_output(monkeypatch, resize, tmp_path)
+    source = tmp_path / "mochi.safetensors"
+    save_file({
+        "diffusion_model.layer.lora_A": torch.ones((2, 2)),
+        "diffusion_model.layer.lora_B": torch.ones((2, 2)),
+        "diffusion_model.layer.alpha": torch.tensor(2.0),
+    }, str(source))
+
+    output = resize.resize_lora_file(
+        str(source), 1, None, None, "cpu", torch.float32,
+        "mochi_normalized", verbose=False,
+    )
+    tensors = load_file(output)
+    assert set(tensors) == {
+        "diffusion_model.layer.lora_A.weight",
+        "diffusion_model.layer.lora_B.weight",
+        "diffusion_model.layer.alpha",
+    }
+
+
+def test_standard_multi_merge_normalizes_mochi_pair_to_preferred_output(
+    monkeypatch, tmp_path, modules
+):
+    _, merger = modules
+    _patch_output(monkeypatch, merger, tmp_path)
+    first = tmp_path / "multi_mochi_a.safetensors"
+    second = tmp_path / "multi_mochi_b.safetensors"
+    for path, value in ((first, 1.0), (second, 3.0)):
+        save_file({
+            "diffusion_model.layer.lora_A": torch.full((1, 2), value),
+            "diffusion_model.layer.lora_B": torch.full((2, 1), value),
+            "diffusion_model.layer.alpha": torch.tensor(1.0),
+        }, str(path))
+
+    output = merger.merge_multi_loras(
+        [str(first), str(second)], [1.0, 1.0], "weighted_sum", "cpu",
+        torch.float32, "multi_mochi_normalized", verbose=False,
+    )
+    tensors = load_file(output)
+
+    assert set(tensors) == {
+        "diffusion_model.layer.lora_A.weight",
+        "diffusion_model.layer.lora_B.weight",
+        "diffusion_model.layer.alpha",
+    }
+
+
+def test_standard_multi_merge_emits_weighted_direct_union(monkeypatch, tmp_path, modules):
+    _, merger = modules
+    _patch_output(monkeypatch, merger, tmp_path)
+    first = tmp_path / "first.safetensors"
+    second = tmp_path / "second.safetensors"
+    base = tmp_path / "multi_base.safetensors"
+    save_file({
+        "model.diffusion_model.norm.weight": torch.zeros(2),
+        "model.diffusion_model.matrix.weight": torch.zeros((2, 2)),
+        "model.diffusion_model.only_first.weight": torch.zeros(()),
+        "model.diffusion_model.scale": torch.zeros(()),
+        "model.diffusion_model.lowrank.weight": torch.zeros((2, 2)),
+    }, str(base))
+    save_file({
+        "diffusion_model.norm.diff": torch.tensor([1.0, 2.0], dtype=torch.bfloat16),
+        "diffusion_model.matrix.diff": torch.ones((2, 2), dtype=torch.float32),
+        "diffusion_model.only_first.diff": torch.tensor(4.0, dtype=torch.bfloat16),
+        "diffusion_model.scale.diff": torch.tensor(1.0, dtype=torch.bfloat16),
+        "diffusion_model.lowrank.lora_down.weight": torch.ones((1, 2), dtype=torch.float32),
+        "diffusion_model.lowrank.lora_up.weight": torch.ones((2, 1), dtype=torch.float32),
+        "diffusion_model.lowrank.alpha": torch.tensor(1.0, dtype=torch.float32),
+    }, str(first))
+    save_file({
+        "diffusion_model.norm.diff": torch.tensor([3.0, 4.0], dtype=torch.bfloat16),
+        "diffusion_model.matrix.diff": torch.full((2, 2), 2.0, dtype=torch.bfloat16),
+        "diffusion_model.lowrank.lora_down.weight": torch.full((1, 2), 2.0, dtype=torch.bfloat16),
+        "diffusion_model.lowrank.lora_up.weight": torch.full((2, 1), 2.0, dtype=torch.bfloat16),
+        "diffusion_model.lowrank.alpha": torch.tensor(1.0, dtype=torch.bfloat16),
+    }, str(second))
+
+    output = merger.merge_multi_loras(
+        [str(first), str(second)], [2.0, -1.0], "concatenate", "cpu",
+        torch.float16, "merged", base_model_path=str(base), verbose=False,
+        include_1d_diffs=True,
+    )
+    tensors = load_file(output)
+
+    torch.testing.assert_close(tensors["diffusion_model.norm.diff"], torch.tensor([-1.0, 0.0]))
+    torch.testing.assert_close(tensors["diffusion_model.matrix.diff"], torch.zeros((2, 2)))
+    assert tensors["diffusion_model.norm.diff"].dtype == torch.float32
+    assert tensors["diffusion_model.matrix.diff"].dtype == torch.float32
+    assert tensors["diffusion_model.only_first.diff"].item() == pytest.approx(8.0)
+    assert tensors["diffusion_model.only_first.diff"].dtype == torch.float16
+    assert tensors["diffusion_model.scale.diff"].item() == pytest.approx(2.0)
+    assert tensors["diffusion_model.lowrank.lora_A.weight"].shape[0] == 2
+    assert tensors["diffusion_model.lowrank.lora_A.weight"].dtype == torch.float32
+    assert tensors["diffusion_model.lowrank.lora_B.weight"].dtype == torch.float32
+    assert tensors["diffusion_model.lowrank.alpha"].dtype == torch.float32
+
+    default_output = merger.merge_multi_loras(
+        [str(first), str(second)], [2.0, -1.0], "concatenate", "cpu",
+        torch.float16, "merged_default", base_model_path=str(base), verbose=False,
+    )
+    default_tensors = load_file(default_output)
+    assert "diffusion_model.norm.diff" not in default_tensors
+    assert "diffusion_model.matrix.diff" in default_tensors
+    assert "diffusion_model.scale.diff" in default_tensors
+    assert "diffusion_model.lowrank.lora_A.weight" in default_tensors
+
+
+def test_multi_merge_rejects_direct_shape_mismatch(monkeypatch, tmp_path, modules):
+    _, merger = modules
+    _patch_output(monkeypatch, merger, tmp_path)
+    first = tmp_path / "shape_first.safetensors"
+    second = tmp_path / "shape_second.safetensors"
+    save_file({"diffusion_model.bad.diff": torch.ones(2)}, str(first))
+    save_file({"diffusion_model.bad.diff": torch.ones(3)}, str(second))
+
+    with pytest.raises(ValueError, match="Direct LoRA shape mismatch"):
+        merger.merge_multi_loras(
+            [str(first), str(second)], [1.0, 1.0], "weighted_sum", "cpu",
+            torch.float16, "bad_shapes", verbose=False, include_1d_diffs=True,
+        )
+
+
+@pytest.mark.parametrize("enhanced", [False, True])
+def test_dare_variants_emit_direct_layers(monkeypatch, tmp_path, modules, enhanced):
+    _, merger = modules
+    _patch_output(monkeypatch, merger, tmp_path)
+    first = tmp_path / f"dare_first_{enhanced}.safetensors"
+    second = tmp_path / f"dare_second_{enhanced}.safetensors"
+    save_file({
+        "diffusion_model.norm.diff": torch.tensor([1.0, 2.0], dtype=torch.bfloat16),
+        "diffusion_model.lowrank.lora_down.weight": torch.ones((1, 2), dtype=torch.float32),
+        "diffusion_model.lowrank.lora_up.weight": torch.ones((2, 1), dtype=torch.float32),
+    }, str(first))
+    save_file({
+        "diffusion_model.norm.diff": torch.tensor([3.0, 4.0], dtype=torch.float32),
+        "diffusion_model.lowrank.lora_down.weight": torch.ones((1, 2), dtype=torch.bfloat16),
+        "diffusion_model.lowrank.lora_up.weight": torch.ones((2, 1), dtype=torch.bfloat16),
+    }, str(second))
+
+    if enhanced:
+        output = merger.merge_multi_loras_dare_enhanced(
+            [str(first), str(second)], [1.0, 1.0], 1.0, 1.0, 0.0, 0.0, 7,
+            "cpu", torch.float16, "enhanced", verbose=False, include_1d_diffs=True,
+        )
+    else:
+        output = merger.merge_multi_loras_dare(
+            [str(first), str(second)], [1.0, 1.0], 0.0, 0.0, 7,
+            "cpu", torch.float16, "dare", verbose=False, include_1d_diffs=True,
+        )
+    tensors = load_file(output)
+
+    torch.testing.assert_close(tensors["diffusion_model.norm.diff"], torch.tensor([2.0, 3.0]))
+    assert tensors["diffusion_model.norm.diff"].dtype == torch.float32
+    assert tensors["diffusion_model.lowrank.lora_A.weight"].dtype == torch.float32
+    assert tensors["diffusion_model.lowrank.lora_B.weight"].dtype == torch.float32
+
+    if enhanced:
+        default_output = merger.merge_multi_loras_dare_enhanced(
+            [str(first), str(second)], [1.0, 1.0], 1.0, 1.0, 0.0, 0.0, 7,
+            "cpu", torch.float16, "enhanced_default", verbose=False,
+        )
+    else:
+        default_output = merger.merge_multi_loras_dare(
+            [str(first), str(second)], [1.0, 1.0], 0.0, 0.0, 7,
+            "cpu", torch.float16, "dare_default", verbose=False,
+        )
+    default_tensors = load_file(default_output)
+    assert "diffusion_model.norm.diff" not in default_tensors
+    assert "diffusion_model.lowrank.lora_A.weight" in default_tensors
+
+
+def test_merge_to_model_applies_generic_direct_keys_and_preserves_dtype(
+    monkeypatch, tmp_path, modules, caplog
+):
+    resize, _ = modules
+    _patch_output(monkeypatch, resize, tmp_path)
+    base = tmp_path / "base.safetensors"
+    adapter = tmp_path / "adapter.safetensors"
+    save_file({
+        "model.diffusion_model.block.weight": torch.zeros((2, 2), dtype=torch.bfloat16),
+        "model.diffusion_model.norm.weight": torch.zeros(2, dtype=torch.bfloat16),
+        "model.diffusion_model.block.bias": torch.zeros(2, dtype=torch.bfloat16),
+        "model.diffusion_model.scale": torch.tensor(1.0, dtype=torch.bfloat16),
+        "model.diffusion_model.lin": torch.zeros((2, 2), dtype=torch.bfloat16),
+        "model.diffusion_model.bad.weight": torch.ones((2, 2), dtype=torch.bfloat16),
+        "model.diffusion_model.untouched": torch.tensor(1e-8, dtype=torch.float32),
+    }, str(base))
+    save_file({
+        "diffusion_model.block.diff": torch.full((2, 2), 1e-8, dtype=torch.float32),
+        "diffusion_model.norm.diff": torch.tensor([1.0, 2.0], dtype=torch.bfloat16),
+        "diffusion_model.block.diff_b": torch.tensor([3.0, 4.0], dtype=torch.bfloat16),
+        "diffusion_model.scale.diff": torch.tensor(0.5, dtype=torch.bfloat16),
+        "diffusion_model.lin.diff": torch.ones((2, 2), dtype=torch.float32),
+        "diffusion_model.bad.diff": torch.ones(3, dtype=torch.float32),
+    }, str(adapter))
+
+    output = resize.merge_loras_to_model(
+        [str(adapter)], [0.5], str(base), "cpu", torch.float16, "merged_model",
+        verbose=False, include_1d_diffs=True,
+    )
+    tensors = load_file(output)
+
+    torch.testing.assert_close(tensors["model.diffusion_model.norm.weight"], torch.tensor([0.5, 1.0]))
+    torch.testing.assert_close(tensors["model.diffusion_model.block.bias"], torch.tensor([1.5, 2.0]))
+    assert tensors["model.diffusion_model.scale"].item() == pytest.approx(1.25)
+    torch.testing.assert_close(tensors["model.diffusion_model.lin"], torch.full((2, 2), 0.5))
+    torch.testing.assert_close(tensors["model.diffusion_model.bad.weight"].float(), torch.ones((2, 2)))
+    assert "Shape mismatch" in caplog.text
+    assert tensors["model.diffusion_model.block.weight"].dtype == torch.float32
+    assert tensors["model.diffusion_model.norm.weight"].dtype == torch.float32
+    assert tensors["model.diffusion_model.block.bias"].dtype == torch.float32
+    assert tensors["model.diffusion_model.scale"].dtype == torch.float16
+    assert tensors["model.diffusion_model.lin"].dtype == torch.float32
+    assert tensors["model.diffusion_model.untouched"].dtype == torch.float32
+
+    default_output = resize.merge_loras_to_model(
+        [str(adapter)], [0.5], str(base), "cpu", torch.float16, "merged_model_default",
+        verbose=False,
+    )
+    default_tensors = load_file(default_output)
+    torch.testing.assert_close(
+        default_tensors["model.diffusion_model.norm.weight"].float(), torch.zeros(2)
+    )
+    torch.testing.assert_close(
+        default_tensors["model.diffusion_model.block.bias"].float(), torch.zeros(2)
+    )
+    assert default_tensors["model.diffusion_model.scale"].item() == pytest.approx(1.25)
+    torch.testing.assert_close(
+        default_tensors["model.diffusion_model.lin"], torch.full((2, 2), 0.5)
+    )
+
+
+def _generic_params(output_filename, override_dtype, include_1d_diffs=False):
+    return {
+        "mismatch_mode": "skip",
+        "alignment_mode": "pad/crop",
+        "alpha": 0.5,
+        "beta": 0.0,
+        "gamma": 0.5,
+        "delta": 2.0,
+        "epsilon": 0.01,
+        "zeta": 0.0,
+        "seed": 0,
+        "output_filename": output_filename,
+        "save_dtype": "bf16",
+        "override_dtype": override_dtype,
+        "device": "cpu",
+        "dtype": torch.float32,
+        "exclude_patterns": "",
+        "discard_patterns": "",
+        "glob_patterns": False,
+        "lazy_load": True,
+        "force_clear_cache": False,
+        "include_1d_diffs": include_1d_diffs,
+    }
+
+
+def test_generic_two_and_three_mergers_enforce_direct_dtype_contract(
+    monkeypatch, tmp_path, generic_modules
+):
+    generic, operations = generic_modules
+    paths = {}
+    for name, tensors in {
+        "a": {
+            "diffusion_model.norm.diff": torch.tensor([1.0, 2.0], dtype=torch.bfloat16),
+            "diffusion_model.matrix.diff": torch.ones((2, 2), dtype=torch.float32),
+        },
+        "b": {
+            "diffusion_model.norm.diff": torch.tensor([3.0, 4.0], dtype=torch.bfloat16),
+            "diffusion_model.matrix.diff": torch.full((2, 2), 3.0, dtype=torch.bfloat16),
+            "diffusion_model.secondary_only.diff": torch.ones(1, dtype=torch.float32),
+        },
+        "c": {
+            "diffusion_model.norm.diff": torch.tensor([0.5, 1.0], dtype=torch.float32),
+            "diffusion_model.matrix.diff": torch.full((2, 2), 0.5, dtype=torch.bfloat16),
+        },
+    }.items():
+        path = tmp_path / f"{name}.safetensors"
+        save_file(tensors, str(path))
+        paths[name] = str(path)
+
+    monkeypatch.setattr(generic.folder_paths, "get_full_path", lambda _, name: paths.get(name))
+    monkeypatch.setattr(generic.folder_paths, "get_folder_paths", lambda _: [str(tmp_path)])
+    monkeypatch.setattr(generic.folder_paths, "models_dir", str(tmp_path))
+    monkeypatch.setattr(generic, "prepare_for_large_operation", lambda *args, **kwargs: None)
+    monkeypatch.setattr(generic, "cleanup_after_operation", lambda: None)
+
+    two_params = _generic_params("generic_two", override_dtype=True)
+    two_params.update({"model_a": "a", "model_b": "b"})
+    generic.MergerLogic.execute_merge(
+        {"model_a": "a", "model_b": "b"},
+        "Weight-Sum",
+        operations.TWO_MODEL_MODES,
+        two_params,
+        "loras",
+    )
+    two = load_file(str(tmp_path / "loras" / "generic_two.safetensors"))
+    torch.testing.assert_close(
+        two["diffusion_model.norm.diff"].float(), torch.tensor([1.0, 2.0])
+    )
+    assert two["diffusion_model.norm.diff"].dtype == torch.bfloat16
+    assert two["diffusion_model.matrix.diff"].dtype == torch.bfloat16
+    assert "diffusion_model.secondary_only.diff" not in two
+
+    two_enabled_params = _generic_params(
+        "generic_two_enabled", override_dtype=True, include_1d_diffs=True
+    )
+    two_enabled_params.update({"model_a": "a", "model_b": "b"})
+    generic.MergerLogic.execute_merge(
+        {"model_a": "a", "model_b": "b"},
+        "Weight-Sum",
+        operations.TWO_MODEL_MODES,
+        two_enabled_params,
+        "loras",
+    )
+    two_enabled = load_file(
+        str(tmp_path / "loras" / "generic_two_enabled.safetensors")
+    )
+    torch.testing.assert_close(
+        two_enabled["diffusion_model.norm.diff"], torch.tensor([2.0, 3.0])
+    )
+    assert two_enabled["diffusion_model.norm.diff"].dtype == torch.float32
+
+    three_params = _generic_params("generic_three", override_dtype=False)
+    three_params.update({"model_a": "a", "model_b": "b", "model_c": "c"})
+    generic.MergerLogic.execute_merge(
+        {"model_a": "a", "model_b": "b", "model_c": "c"},
+        "Add-Difference",
+        operations.THREE_MODEL_MODES,
+        three_params,
+        "loras",
+    )
+    three = load_file(str(tmp_path / "loras" / "generic_three.safetensors"))
+    torch.testing.assert_close(
+        three["diffusion_model.norm.diff"].float(), torch.tensor([1.0, 2.0])
+    )
+    assert three["diffusion_model.norm.diff"].dtype == torch.bfloat16
+    assert three["diffusion_model.matrix.diff"].dtype == torch.float32
+
+    three_enabled_params = _generic_params(
+        "generic_three_enabled", override_dtype=False, include_1d_diffs=True
+    )
+    three_enabled_params.update({"model_a": "a", "model_b": "b", "model_c": "c"})
+    generic.MergerLogic.execute_merge(
+        {"model_a": "a", "model_b": "b", "model_c": "c"},
+        "Add-Difference",
+        operations.THREE_MODEL_MODES,
+        three_enabled_params,
+        "loras",
+    )
+    three_enabled = load_file(
+        str(tmp_path / "loras" / "generic_three_enabled.safetensors")
+    )
+    torch.testing.assert_close(
+        three_enabled["diffusion_model.norm.diff"], torch.tensor([2.25, 3.5])
+    )
+    assert three_enabled["diffusion_model.norm.diff"].dtype == torch.float32

tests/test_lora_quantization_guard.py

@@ -0,0 +1,437 @@
+import importlib
+import json
+import logging
+import struct
+import sys
+import types
+from pathlib import Path
+
+import pytest
+import torch
+from safetensors.torch import load_file, save_file
+
+
+REPO_ROOT = Path(__file__).resolve().parents[1]
+PACKAGE_NAME = "modelutils_quant_guard_tests"
+
+
+def _load_module(name):
+    if PACKAGE_NAME not in sys.modules:
+        package = types.ModuleType(PACKAGE_NAME)
+        package.__path__ = [str(REPO_ROOT)]
+        sys.modules[PACKAGE_NAME] = package
+    return importlib.import_module(f"{PACKAGE_NAME}.{name}")
+
+
+@pytest.fixture(scope="module")
+def modules():
+    return {
+        "guard": _load_module("nodes.quantization_guard"),
+        "extract": _load_module("nodes.lora_extract_svd"),
+        "resize": _load_module("nodes.lora_resize"),
+        "multi": _load_module("nodes.lora_merger"),
+        "generic": _load_module("nodes.merger"),
+        "operations": _load_module("nodes.merger_ops"),
+    }
+
+
+def _patch_output(monkeypatch, module, output_dir):
+    monkeypatch.setattr(module.folder_paths, "get_folder_paths", lambda _: [str(output_dir)])
+    monkeypatch.setattr(module.folder_paths, "models_dir", str(output_dir))
+    monkeypatch.setattr(module, "prepare_for_large_operation", lambda *args, **kwargs: None)
+    monkeypatch.setattr(module, "cleanup_after_operation", lambda: None)
+
+
+def _inspect_file(path, modules, label="input"):
+    handler = modules["resize"].MemoryEfficientSafeOpen(str(path), low_memory=True)
+    try:
+        return modules["guard"].inspect_low_bit_input(handler, label, "Guard Test")
+    finally:
+        handler.__exit__(None, None, None)
+
+
+def _round_trip_preserved(path, output, modules):
+    handler = modules["resize"].MemoryEfficientSafeOpen(str(path), low_memory=True)
+    try:
+        with modules["resize"].IncrementalSafetensorsWriter(str(output)) as writer:
+            modules["guard"].write_preserved_tensor(writer, "low", handler)
+    finally:
+        handler.__exit__(None, None, None)
+    return load_file(str(output))["low"]
+
+
+def _tensor_payload(path, key="low"):
+    with open(path, "rb") as source:
+        header_size = struct.unpack("<Q", source.read(8))[0]
+        header = json.loads(source.read(header_size).decode("utf-8"))
+        start, end = header[key]["data_offsets"]
+        source.seek(8 + header_size + start)
+        return source.read(end - start)
+
+
+@pytest.mark.parametrize("dtype", [torch.int8, torch.uint8])
+def test_int8_uint8_are_detected_and_warn_once(tmp_path, modules, caplog, dtype):
+    path = tmp_path / f"{dtype}.safetensors"
+    save_file({"low": torch.arange(4, dtype=dtype), "normal": torch.ones(1)}, str(path))
+
+    with caplog.at_level(logging.WARNING):
+        detected = _inspect_file(path, modules, "threshold input")
+
+    assert detected == {"low"}
+    records = [record for record in caplog.records if "threshold input" in record.message]
+    assert len(records) == 1
+    assert "1 isolated low-bit tensor" in records[0].message
+    assert "low" in records[0].message
+
+
+def test_exact_two_tensor_threshold(tmp_path, modules):
+    for count in range(4):
+        path = tmp_path / f"threshold_{count}.safetensors"
+        tensors = {f"low_{i}": torch.ones(2, dtype=torch.uint8) for i in range(count)}
+        tensors["normal"] = torch.ones(1)
+        save_file(tensors, str(path))
+        if count <= 2:
+            assert len(_inspect_file(path, modules)) == count
+        else:
+            with pytest.raises(ValueError, match="3 low-bit tensors.*casted or quantized"):
+                _inspect_file(path, modules)
+
+
+@pytest.mark.parametrize(
+    ("tensors", "metadata"),
+    [
+        ({"layer.comfy_quant": torch.tensor([123], dtype=torch.uint8)}, None),
+        ({"normal": torch.ones(1)}, {"_quantization_metadata": "{}"}),
+        ({"scaled_fp8": torch.ones(2)}, None),
+    ],
+)
+def test_recognized_comfy_quantization_hard_errors(tmp_path, modules, tensors, metadata):
+    path = tmp_path / f"quant_{len(list(tmp_path.iterdir()))}.safetensors"
+    save_file(tensors, str(path), metadata=metadata)
+    with pytest.raises(ValueError, match="ComfyUI quantization metadata.*unsupported"):
+        _inspect_file(path, modules, "recognized input")
+
+
+def test_supported_fp8_storage_round_trip(tmp_path, modules):
+    candidates = [
+        dtype
+        for name in (
+            "float8_e4m3fn", "float8_e4m3fnuz", "float8_e5m2", "float8_e5m2fnuz",
+            "float8_e8m0fnu",
+        )
+        if (dtype := getattr(torch, name, None)) is not None
+    ]
+    supported = []
+    for index, dtype in enumerate(candidates):
+        path = tmp_path / f"low_float_{index}.safetensors"
+        try:
+            save_file({"low": torch.zeros(4, dtype=dtype)}, str(path))
+            loaded = load_file(str(path))["low"]
+        except (KeyError, RuntimeError, TypeError, ValueError):
+            continue
+        supported.append(dtype)
+        assert loaded.dtype == dtype
+        assert _inspect_file(path, modules) == {"low"}
+        preserved = _round_trip_preserved(path, tmp_path / f"preserved_{index}.safetensors", modules)
+        assert preserved.dtype == dtype
+        torch.testing.assert_close(preserved.float(), loaded.float())
+
+    if candidates and not supported:
+        pytest.skip("Installed safetensors cannot write any installed torch FP8 dtype")
+
+
+def test_fp4_storage_when_supported(tmp_path, modules):
+    dtype = getattr(torch, "float4_e2m1fn_x2", None)
+    if dtype is None:
+        pytest.skip("Installed PyTorch has no torch.float4_e2m1fn_x2")
+    path = tmp_path / "fp4.safetensors"
+    try:
+        save_file({"low": torch.zeros(4, dtype=dtype)}, str(path))
+        loaded = load_file(str(path))["low"]
+    except (KeyError, RuntimeError, TypeError, ValueError):
+        pytest.skip("Installed safetensors cannot write torch.float4_e2m1fn_x2")
+    assert loaded.dtype == dtype
+    assert _inspect_file(path, modules) == {"low"}
+    preserved = _round_trip_preserved(path, tmp_path / "preserved_fp4.safetensors", modules)
+    assert preserved.dtype == dtype
+    assert _tensor_payload(path) == _tensor_payload(tmp_path / "preserved_fp4.safetensors")
+
+
+def test_realistic_packed_uint8_comfy_sidecar_is_rejected(tmp_path, modules):
+    path = tmp_path / "packed_comfy.safetensors"
+    save_file({
+        "layer.weight": torch.arange(8, dtype=torch.uint8).reshape(2, 4),
+        "layer.comfy_quant": torch.tensor(list(b'{"format":"int8"}'), dtype=torch.uint8),
+        "layer.weight_scale": torch.ones(2),
+    }, str(path))
+    with pytest.raises(ValueError, match="ComfyUI quantization metadata"):
+        _inspect_file(path, modules)
+
+
+def test_resize_preserves_complete_low_bit_layer_and_resizes_normal(
+    monkeypatch, tmp_path, modules
+):
+    resize = modules["resize"]
+    _patch_output(monkeypatch, resize, tmp_path)
+    source = tmp_path / "resize_quant.safetensors"
+    guarded_down = torch.tensor([[1, 2], [3, 4]], dtype=torch.uint8)
+    save_file({
+        "diffusion_model.guarded.lora_down.weight": guarded_down,
+        "diffusion_model.guarded.lora_up.weight": torch.ones((2, 2)),
+        "diffusion_model.guarded.alpha": torch.tensor(2.0),
+        "diffusion_model.guarded.dora_scale": torch.tensor([0.125, 0.25]),
+        "diffusion_model.normal.lora_down.weight": torch.ones((2, 2)),
+        "diffusion_model.normal.lora_up.weight": torch.ones((2, 2)),
+        "isolated_aux": torch.tensor([7], dtype=torch.int8),
+    }, str(source))
+
+    output = resize.resize_lora_file(
+        str(source), 1, None, None, "cpu", torch.float16, "resize_guarded", verbose=False
+    )
+    result = load_file(output)
+    torch.testing.assert_close(result["diffusion_model.guarded.lora_A.weight"], guarded_down)
+    assert result["diffusion_model.guarded.lora_A.weight"].dtype == torch.uint8
+    assert result["diffusion_model.guarded.lora_B.weight"].dtype == torch.float32
+    assert result["diffusion_model.guarded.dora_scale"].dtype == torch.float32
+    assert result["diffusion_model.normal.lora_A.weight"].shape[0] == 1
+    assert result["isolated_aux"].dtype == torch.int8
+
+
+def test_extract_excludes_low_bit_candidate_and_extracts_float_layer(
+    monkeypatch, tmp_path, modules
+):
+    extract = modules["extract"]
+    monkeypatch.setattr(extract, "prepare_for_large_operation", lambda *args, **kwargs: None)
+    monkeypatch.setattr(extract, "cleanup_after_operation", lambda: None)
+    model_a = tmp_path / "extract_a.safetensors"
+    model_b = tmp_path / "extract_b.safetensors"
+    output = tmp_path / "extracted.safetensors"
+    save_file({
+        "model.diffusion_model.normal.weight": torch.eye(2),
+        "model.diffusion_model.quant.weight": torch.ones((2, 2), dtype=torch.uint8),
+    }, str(model_a))
+    save_file({
+        "model.diffusion_model.normal.weight": torch.zeros((2, 2)),
+        "model.diffusion_model.quant.weight": torch.zeros((2, 2), dtype=torch.uint8),
+    }, str(model_b))
+
+    extract.extract_lora_from_files(
+        str(model_a), str(model_b), "fixed", 1, 1, "cpu", "fp32", str(output),
+        force_clear_cache=False,
+    )
+    result = load_file(str(output))
+    assert any("normal" in key for key in result)
+    assert not any("quant" in key for key in result)
+
+
+def test_extract_bias_diff_round_trips_through_merge_to_model(
+    monkeypatch, tmp_path, modules
+):
+    extract = modules["extract"]
+    resize = modules["resize"]
+    monkeypatch.setattr(extract, "prepare_for_large_operation", lambda *args, **kwargs: None)
+    monkeypatch.setattr(extract, "cleanup_after_operation", lambda: None)
+    _patch_output(monkeypatch, resize, tmp_path)
+
+    finetuned = tmp_path / "bias_finetuned.safetensors"
+    base = tmp_path / "bias_base.safetensors"
+    adapter = tmp_path / "bias_adapter.safetensors"
+    save_file({
+        "model.diffusion_model.layer.bias": torch.tensor([0.25, -0.5]),
+    }, str(finetuned))
+    save_file({
+        "model.diffusion_model.layer.bias": torch.tensor([0.0, 0.5]),
+    }, str(base))
+
+    extract.extract_lora_from_files(
+        str(finetuned), str(base), "fixed", 1, 1, "cpu", "fp16", str(adapter),
+        force_clear_cache=False, include_1d_diffs=True,
+    )
+    extracted = load_file(str(adapter))
+    assert set(extracted) == {"diffusion_model.layer.diff_b"}
+    assert extracted["diffusion_model.layer.diff_b"].dtype == torch.float32
+
+    merged_path = resize.merge_loras_to_model(
+        [str(adapter)], [1.0], str(base), "cpu", torch.float32,
+        "bias_round_trip", verbose=False, include_1d_diffs=True,
+    )
+    merged = load_file(merged_path)
+    torch.testing.assert_close(
+        merged["model.diffusion_model.layer.bias"],
+        load_file(str(finetuned))["model.diffusion_model.layer.bias"],
+    )
+
+
+def _run_multi_variant(module, variant, paths, output_name):
+    common = (paths, [1.0, 1.0])
+    if variant == "standard":
+        return module.merge_multi_loras(
+            *common, "weighted_sum", "cpu", torch.float16, output_name,
+            verbose=False, include_1d_diffs=True,
+        )
+    if variant == "dare":
+        return module.merge_multi_loras_dare(
+            *common, 0.0, 0.0, 11, "cpu", torch.float16, output_name,
+            verbose=False, include_1d_diffs=True,
+        )
+    return module.merge_multi_loras_dare_enhanced(
+        *common, 1.0, 1.0, 0.0, 0.0, 11, "cpu", torch.float16, output_name,
+        verbose=False, include_1d_diffs=True,
+    )
+
+
+@pytest.mark.parametrize("variant", ["standard", "dare", "enhanced"])
+def test_multi_variants_preserve_earliest_complete_affected_layer(
+    monkeypatch, tmp_path, modules, variant
+):
+    multi = modules["multi"]
+    _patch_output(monkeypatch, multi, tmp_path)
+    first = tmp_path / f"{variant}_first.safetensors"
+    second = tmp_path / f"{variant}_second.safetensors"
+    first_down = torch.tensor([[1.0, 2.0]])
+    save_file({
+        "diffusion_model.guarded.lora_down.weight": first_down,
+        "diffusion_model.guarded.lora_up.weight": torch.tensor([[3.0], [4.0]]),
+        "diffusion_model.guarded.dora_scale": torch.tensor([0.125, 0.25]),
+        "diffusion_model.normal.diff": torch.ones((2, 2)),
+    }, str(first))
+    save_file({
+        "diffusion_model.guarded.lora_down.weight": torch.tensor([[1, 2]], dtype=torch.uint8),
+        "diffusion_model.guarded.lora_up.weight": torch.tensor([[9.0], [9.0]]),
+        "diffusion_model.guarded.dora_scale": torch.tensor([9.0, 9.0]),
+        "diffusion_model.normal.diff": torch.full((2, 2), 3.0),
+    }, str(second))
+
+    output = _run_multi_variant(multi, variant, [str(first), str(second)], f"guard_{variant}")
+    result = load_file(output)
+    torch.testing.assert_close(result["diffusion_model.guarded.lora_A.weight"], first_down)
+    torch.testing.assert_close(
+        result["diffusion_model.guarded.lora_B.weight"], torch.tensor([[3.0], [4.0]])
+    )
+    torch.testing.assert_close(
+        result["diffusion_model.guarded.dora_scale"], torch.tensor([0.125, 0.25])
+    )
+    assert "diffusion_model.normal.diff" in result
+
+
+def test_hard_error_happens_before_resize_output_creation(monkeypatch, tmp_path, modules):
+    resize = modules["resize"]
+    _patch_output(monkeypatch, resize, tmp_path)
+    source = tmp_path / "three_low.safetensors"
+    save_file({f"low_{i}": torch.ones(1, dtype=torch.uint8) for i in range(3)}, str(source))
+    output = tmp_path / "must_not_exist.safetensors"
+
+    with pytest.raises(ValueError, match="3 low-bit tensors"):
+        resize.resize_lora_file(
+            str(source), 1, None, None, "cpu", torch.float16, output.stem, verbose=False
+        )
+    assert not output.exists()
+
+
+def test_recognized_quantization_creates_no_resize_output(monkeypatch, tmp_path, modules):
+    resize = modules["resize"]
+    _patch_output(monkeypatch, resize, tmp_path)
+    source = tmp_path / "recognized_quant.safetensors"
+    save_file({
+        "layer.weight": torch.ones((2, 2)),
+        "layer.comfy_quant": torch.tensor(list(b'{"format":"int8"}'), dtype=torch.uint8),
+    }, str(source))
+    output = tmp_path / "recognized_must_not_exist.safetensors"
+
+    with pytest.raises(ValueError, match="ComfyUI quantization metadata"):
+        resize.resize_lora_file(
+            str(source), 1, None, None, "cpu", torch.float16, output.stem, verbose=False
+        )
+    assert not output.exists()
+
+
+def _generic_params(output_filename):
+    return {
+        "mismatch_mode": "skip", "alignment_mode": "pad/crop", "alpha": 0.5,
+        "beta": 0.0, "gamma": 0.5, "delta": 2.0, "epsilon": 0.01, "zeta": 0.0,
+        "seed": 0, "output_filename": output_filename, "save_dtype": "bf16",
+        "override_dtype": True, "device": "cpu", "dtype": torch.float32,
+        "exclude_patterns": "", "discard_patterns": "", "glob_patterns": False,
+        "lazy_load": True, "force_clear_cache": False, "include_1d_diffs": True,
+    }
+
+
+def test_generic_merge_preserves_model_a_when_either_source_key_is_low_bit(
+    monkeypatch, tmp_path, modules
+):
+    generic = modules["generic"]
+    operations = modules["operations"]
+    model_a = tmp_path / "generic_guard_a.safetensors"
+    model_b = tmp_path / "generic_guard_b.safetensors"
+    a_tensors = {
+        "a_low": torch.tensor([[1, 2]], dtype=torch.uint8),
+        "b_low": torch.tensor([[0.125, 0.25]], dtype=torch.float32),
+        "normal": torch.ones((1, 2)),
+    }
+    save_file(a_tensors, str(model_a))
+    save_file({
+        "a_low": torch.tensor([[9.0, 9.0]]),
+        "b_low": torch.tensor([[3, 4]], dtype=torch.int8),
+        "normal": torch.full((1, 2), 3.0),
+    }, str(model_b))
+    paths = {"a": str(model_a), "b": str(model_b)}
+    monkeypatch.setattr(generic.folder_paths, "get_full_path", lambda _, name: paths[name])
+    monkeypatch.setattr(generic.folder_paths, "get_folder_paths", lambda _: [str(tmp_path)])
+    monkeypatch.setattr(generic.folder_paths, "models_dir", str(tmp_path))
+    monkeypatch.setattr(generic, "prepare_for_large_operation", lambda *args, **kwargs: None)
+    monkeypatch.setattr(generic, "cleanup_after_operation", lambda: None)
+    params = _generic_params("generic_guarded")
+    params.update({"model_a": "a", "model_b": "b"})
+
+    generic.MergerLogic.execute_merge(
+        {"model_a": "a", "model_b": "b"}, "Weight-Sum",
+        operations.TWO_MODEL_MODES, params, "loras",
+    )
+    result = load_file(
+        str(tmp_path / "loras" / "generic_guarded.safetensors")
+    )
+    torch.testing.assert_close(result["a_low"], a_tensors["a_low"])
+    torch.testing.assert_close(result["b_low"], a_tensors["b_low"])
+    assert result["a_low"].dtype == torch.uint8
+    assert result["b_low"].dtype == torch.float32
+    torch.testing.assert_close(result["normal"].float(), torch.full((1, 2), 2.0))
+
+
+def test_merge_to_model_preserves_low_bit_base_and_skips_low_bit_adapter_layer(
+    monkeypatch, tmp_path, modules
+):
+    resize = modules["resize"]
+    _patch_output(monkeypatch, resize, tmp_path)
+    base = tmp_path / "merge_guard_base.safetensors"
+    adapter = tmp_path / "merge_guard_adapter.safetensors"
+    base_quant = torch.tensor([[1, 2], [3, 4]], dtype=torch.uint8)
+    save_file({
+        "model.diffusion_model.base_quant.weight": base_quant,
+        "model.diffusion_model.guarded.weight": torch.zeros((2, 2)),
+        "model.diffusion_model.normal.weight": torch.zeros((2, 2)),
+    }, str(base))
+    save_file({
+        "diffusion_model.guarded.lora_down.weight": torch.tensor([[1, 1]], dtype=torch.int8),
+        "diffusion_model.guarded.lora_up.weight": torch.ones((2, 1)),
+        "diffusion_model.guarded.diff": torch.full((2, 2), 5.0),
+        "diffusion_model.normal.diff": torch.ones((2, 2)),
+    }, str(adapter))
+
+    output, report = resize.merge_loras_to_model(
+        [str(adapter)], [1.0], str(base), "cpu", torch.float16, "merge_guarded",
+        verbose=False, include_1d_diffs=True, return_report=True,
+    )
+    result = load_file(output)
+    torch.testing.assert_close(result["model.diffusion_model.base_quant.weight"], base_quant)
+    assert result["model.diffusion_model.base_quant.weight"].dtype == torch.uint8
+    torch.testing.assert_close(
+        result["model.diffusion_model.guarded.weight"].float(), torch.zeros((2, 2))
+    )
+    torch.testing.assert_close(
+        result["model.diffusion_model.normal.weight"].float(), torch.ones((2, 2))
+    )
+    assert report.startswith("COMPLETED WITH EXCLUSIONS: 1/2")
+    assert "[GUARDED] (1)" in report
+    assert "diffusion_model.guarded.lora_down.weight" in report
+    assert "torch.int8" in report
+    assert "model.diffusion_model.base_quant.weight" in report