Bandaid fix

Author: BrianMichell

src/mdio/converters/segy.py

@@ -371,15 +371,19 @@ def _scalar_to_size(scalar: ScalarType2) -> int:
         raise ValueError(f"Invalid scalar type: {scalar}")
 
 def _customize_segy_spec(segy_spec: SegySpec) -> SegySpec:
+    from copy import deepcopy
     assigned_bytes = []
+
+    ret = deepcopy(segy_spec)
+
     for field in segy_spec.trace.header.fields:
         byte = field.byte-1
         for i in range(byte, byte + _scalar_to_size(field.format)):
             assigned_bytes.append(i)
     unassigned_bytes = [i for i in range(240) if i not in assigned_bytes]
-    field_to_customize = [HeaderField(name=f"Field_{i}", format=ScalarType.UINT8, byte=i+1) for i in unassigned_bytes]
-    segy_spec = segy_spec.customize(trace_header_fields=field_to_customize)
-    return segy_spec
+    field_to_customize = [HeaderField(name=f"__MDIO_RAW_UNSPECIFIED_Field_{i}", format=ScalarType.UINT8, byte=i+1) for i in unassigned_bytes]
+    ret = ret.customize(trace_header_fields=field_to_customize)
+    return ret
 
 
 def _add_raw_headers_to_template(mdio_template: AbstractDatasetTemplate) -> AbstractDatasetTemplate:

src/mdio/segy/creation.py

@@ -28,6 +28,39 @@
 logger = logging.getLogger(__name__)
 
 
+def _filter_raw_unspecified_fields(headers: NDArray) -> NDArray:
+    """Filter out __MDIO_RAW_UNSPECIFIED_Field_* fields from headers array.
+    
+    These fields are added during SEGY import to preserve raw header bytes,
+    but they cause dtype mismatches during export. This function removes them.
+    
+    Args:
+        headers: Header array that may contain raw unspecified fields.
+        
+    Returns:
+        Header array with raw unspecified fields removed.
+    """
+    if headers.dtype.names is None:
+        return headers
+        
+    # Find field names that don't start with __MDIO_RAW_UNSPECIFIED_
+    field_names = [name for name in headers.dtype.names 
+                   if not name.startswith("__MDIO_RAW_UNSPECIFIED_")]
+    
+    if len(field_names) == len(headers.dtype.names):
+        # No raw unspecified fields found, return as-is
+        return headers
+    
+    # Create new structured array with only the non-raw fields
+    new_dtype = [(name, headers.dtype.fields[name][0]) for name in field_names]
+    filtered_headers = np.empty(headers.shape, dtype=new_dtype)
+    
+    for name in field_names:
+        filtered_headers[name] = headers[name]
+        
+    return filtered_headers
+
+
 def make_segy_factory(spec: SegySpec, binary_header: dict[str, int]) -> SegyFactory:
     """Generate SEG-Y factory from MDIO metadata."""
     sample_interval = binary_header["sample_interval"]
@@ -167,7 +200,9 @@ def serialize_to_segy_stack(  # noqa: PLR0913
         samples = samples[live_mask]
         headers = headers[live_mask]
 
-        buffer = segy_factory.create_traces(headers, samples)
+        # Filter out raw unspecified fields that cause dtype mismatches
+        filtered_headers = _filter_raw_unspecified_fields(headers)
+        buffer = segy_factory.create_traces(filtered_headers, samples)
 
         global_index = block_start[0]
         record_id_str = str(global_index)
@@ -199,7 +234,9 @@ def serialize_to_segy_stack(  # noqa: PLR0913
             rec_samples = samples[rec_index][rec_live_mask]
             rec_headers = headers[rec_index][rec_live_mask]
 
-            buffer = segy_factory.create_traces(rec_headers, rec_samples)
+            # Filter out raw unspecified fields that cause dtype mismatches
+            filtered_headers = _filter_raw_unspecified_fields(rec_headers)
+            buffer = segy_factory.create_traces(filtered_headers, rec_samples)
 
             global_index = tuple(block_start[i] + rec_index[i] for i in range(record_ndim))
             record_id_str = "/".join(map(str, global_index))