diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index d06777a..7fe13ac 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -25,3 +25,22 @@ repos:
               subworkflows/nf-core/.*|
               .*\.snap$
           )$
+  - repo: local
+    hooks:
+      - id: ban-moduledir-templates-shell-call
+        name: Ban "python3 ${moduleDir}/templates/" shell-call invocation
+        description: |
+          The pattern `python3 ${moduleDir}/templates/<script>.py` (introduced by
+          PR #154 in May 2026) breaks on Seqera Platform (Tower) running AWS
+          Batch: ${moduleDir} interpolates to a head-node path (typically
+          /.nextflow/assets/<user>/<repo>/...) that does not exist on the worker
+          containers, so every task fails at start with
+          "python3: can't open file '/.nextflow/...': No such file or directory".
+          Use top-level bin/ scripts invoked by name via PATH (canonical
+          nf-core pattern), or declare the template as a `path` input so
+          Nextflow stages it to the worker. See PR #154 discussion for
+          empirical evidence from the 2026-05-28 Atera compatibility evaluation.
+        language: pygrep
+        types: [text]
+        files: ^modules/local/.*\.nf$
+        entry: '\$\{moduleDir\}/templates/'
diff --git a/bin/utility_parquet_to_csv.py b/bin/utility_parquet_to_csv.py
index bfa19c4..785b97c 100755
--- a/bin/utility_parquet_to_csv.py
+++ b/bin/utility_parquet_to_csv.py
@@ -1,47 +1,52 @@
 #!/usr/bin/env python3
 """
-Convert a Parquet file to CSV format.
+Stream-convert a Parquet file to CSV format using pyarrow batched I/O.
 
-Reads a Parquet file and writes it as CSV, optionally gzip-compressed.
+Pure format transformation: every input row maps to one output row.
+Memory usage is bounded by --batch-size (default 200_000 rows) rather
+than the full row count, so this works on large bundles (e.g. the 10x
+Atera WTA panel: 236M rows x 13 cols) within ~200 MB of RAM rather
+than the ~30 GB the previous pandas-based eager loader required.
 """
 
 import argparse
+import gzip
 from pathlib import Path
 
-import pandas as pd
+import pyarrow.csv as pa_csv
+import pyarrow.parquet as pq
 
 
-def convert_parquet(
+def stream_parquet_to_csv(
     transcripts: str,
-    extension: str = ".csv",
-    prefix: str = "",
+    extension: str,
+    prefix: str,
+    batch_size: int,
 ) -> None:
-    """
-    Convert a Parquet file to CSV or CSV.GZ format.
-
-    Args:
-        transcripts: Filename of the input parquet file
-        extension: Output extension ('.csv' or '.gz' for gzip)
-        prefix: Output directory prefix
-    """
-    df = pd.read_parquet(transcripts, engine="pyarrow")
-
+    """Stream a Parquet file to CSV (optionally gzip-compressed)."""
     Path(prefix).mkdir(parents=True, exist_ok=True)
+    pf = pq.ParquetFile(transcripts)
 
     if extension == ".gz":
-        output = transcripts.replace(".parquet", ".csv.gz")
-        df.to_csv(f"{prefix}/{output}", compression="gzip", index=False)
+        out_path = f"{prefix}/" + transcripts.replace(".parquet", ".csv.gz")
+        # pyarrow's CSVWriter writes bytes; wrap a gzip stream.
+        sink = gzip.open(out_path, "wb")
     else:
-        output = transcripts.replace(".parquet", ".csv")
-        df.to_csv(f"{prefix}/{output}", index=False)
+        out_path = f"{prefix}/" + transcripts.replace(".parquet", ".csv")
+        sink = open(out_path, "wb")
 
-    return None
+    try:
+        with pa_csv.CSVWriter(sink, pf.schema_arrow) as writer:
+            for batch in pf.iter_batches(batch_size=batch_size):
+                writer.write_batch(batch)
+    finally:
+        sink.close()
 
 
 def parse_args() -> argparse.Namespace:
     """Parse command-line arguments."""
     parser = argparse.ArgumentParser(
-        description="Convert a Parquet file to CSV format."
+        description="Stream-convert a Parquet file to CSV format."
     )
     parser.add_argument(
         "--transcripts",
@@ -58,13 +63,20 @@ def parse_args() -> argparse.Namespace:
         required=True,
         help="Output directory prefix (sample ID)",
     )
+    parser.add_argument(
+        "--batch-size",
+        type=int,
+        default=200_000,
+        help="Rows per batch (default 200000). Memory ~= batch_size * row_size.",
+    )
     return parser.parse_args()
 
 
 if __name__ == "__main__":
     args = parse_args()
-    convert_parquet(
+    stream_parquet_to_csv(
         transcripts=args.transcripts,
         extension=args.extension,
         prefix=args.prefix,
+        batch_size=args.batch_size,
     )
diff --git a/workflows/spatialaxe.nf b/workflows/spatialaxe.nf
index 8e11f05..6f10e85 100644
--- a/workflows/spatialaxe.nf
+++ b/workflows/spatialaxe.nf
@@ -333,24 +333,34 @@ workflow SPATIALAXE {
 
     // get gene_panel.json if provided with --gene_panel, sets relabel_genes to true
     def do_relabel = gene_panel ? true : relabel_genes
-    if (gene_panel) {
 
-        def gene_panel_file = file(gene_panel, checkIfExists: true)
-        ch_gene_panel = ch_input.map { meta, _bundle, _image ->
-            return [meta, gene_panel_file]
+    // Only construct ch_gene_panel when relabel will actually run.
+    // The .map { file(..., checkIfExists: true) } closure is evaluated eagerly
+    // by Nextflow as soon as ch_input emits — even if ch_gene_panel is never
+    // consumed downstream — so leaving this block unconditional breaks every
+    // bundle that ships without gene_panel.json (e.g. 10x Atera / Xenium Gen2),
+    // even in modes that never invoke XENIUMRANGER_RELABEL_RESEGMENT.
+    if (do_relabel) {
+        if (gene_panel) {
+
+            def gene_panel_file = file(gene_panel, checkIfExists: true)
+            ch_gene_panel = ch_input.map { meta, _bundle, _image ->
+                return [meta, gene_panel_file]
+            }
         }
-    }
-    else {
+        else {
 
-        // gene panel to use if only --relabel_genes is provided
-        ch_gene_panel = ch_input.map { meta, bundle, _image ->
-            def gene_panel_file = file(
-                bundle.toString().replaceFirst(/\/$/, '') + "/gene_panel.json",
-                checkIfExists: true
-            )
-            return [meta, gene_panel_file]
+            // gene panel to use if only --relabel_genes is provided
+            ch_gene_panel = ch_input.map { meta, bundle, _image ->
+                def gene_panel_file = file(
+                    bundle.toString().replaceFirst(/\/$/, '') + "/gene_panel.json",
+                    checkIfExists: true
+                )
+                return [meta, gene_panel_file]
+            }
         }
     }
+    // else: ch_gene_panel keeps its initial channel.empty() value from line 112
 
     /*
     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~