diff --git a/config.json b/config.json
index 003b2b6..3513b2d 100644
--- a/config.json
+++ b/config.json
@@ -1,6 +1,6 @@
 {
   "dailyFormat": "daily_YYMMDD",
-  "structDir": "D:\\ProjectStructure",
+  "structDir": "T:\\3 ProjectStructure",
   "zipper": "7z",
   "compression": 9
 }
diff --git a/zip_sequences.py b/zip_sequences.py
index fb45229..7725b5f 100644
--- a/zip_sequences.py
+++ b/zip_sequences.py
@@ -11,10 +11,11 @@ from __future__ import annotations
 
 import argparse
 import json
-import subprocess
 import os
 import shutil
+import subprocess
 import sys
+import tempfile
 from concurrent.futures import ThreadPoolExecutor, as_completed
 from pathlib import Path
 from typing import Iterator, Sequence
@@ -67,7 +68,6 @@ if isinstance(zipper_val, bool):
     ZIPPER_TYPE = "7z" if zipper_val else "zip"
 else:
     ZIPPER_TYPE = str(zipper_val).lower()
-USE_7Z = ZIPPER_TYPE == "7z"
 COMPRESSION_LEVEL = CONFIG.get("compression", 9)
 if isinstance(COMPRESSION_LEVEL, str):
     try:
@@ -79,11 +79,10 @@ if not isinstance(COMPRESSION_LEVEL, int):
 COMPRESSION_LEVEL = max(0, min(9, COMPRESSION_LEVEL))
 
 SEVEN_Z_EXE: str | None = None
-if USE_7Z:
+if ZIPPER_TYPE == "7z":
     SEVEN_Z_EXE = shutil.which("7z") or shutil.which("7za")
     if SEVEN_Z_EXE is None:
-        print("[zip] Requested 7z compression but no 7z executable was found; falling back to zipfile.", file=sys.stderr)
-        USE_7Z = False
+        print("[zip] Warning: 7z compression requested but no 7z executable was found in PATH.", file=sys.stderr)
 
 
 def parse_args() -> argparse.Namespace:
@@ -192,20 +191,47 @@ def state_path_for(zip_path: Path) -> Path:
 
 
 def zip_sequence(seq_dir: Path, zip_path: Path) -> None:
-    if USE_7Z and SEVEN_Z_EXE:
+    if ZIPPER_TYPE == "7z":
+        if SEVEN_Z_EXE is None:
+            raise RuntimeError("7z compression requested but 7z executable not found in PATH")
         zip_path.parent.mkdir(parents=True, exist_ok=True)
-        cmd = [
-            SEVEN_Z_EXE,
-            "a",
-            "-y",
-            f"-mx={COMPRESSION_LEVEL}",
-            "-tzip",
-            str(zip_path),
-            ".\\*",
-        ]
-        subprocess.run(cmd, cwd=seq_dir, check=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
+        # Build list of files to archive with relative paths
+        file_list = []
+        for file_path in iter_sequence_files(seq_dir):
+            rel_path = file_path.relative_to(seq_dir).as_posix()
+            file_list.append(rel_path)
+        
+        # Use a temporary list file to avoid Windows command line length limits
+        with tempfile.NamedTemporaryFile(mode="w", suffix=".lst", delete=False, encoding="utf-8") as list_file:
+            list_file_path = Path(list_file.name)
+            for rel_path in file_list:
+                list_file.write(rel_path + "\n")
+        
+        try:
+            cmd = [
+                SEVEN_Z_EXE,
+                "a",
+                "-y",
+                f"-mx={COMPRESSION_LEVEL}",
+                "-tzip",
+                str(zip_path),
+                f"@{list_file_path}",
+            ]
+            result = subprocess.run(
+                cmd,
+                cwd=seq_dir,
+                check=False,
+                stdout=subprocess.PIPE,
+                stderr=subprocess.PIPE,
+                text=True,
+            )
+            if result.returncode != 0:
+                raise RuntimeError(f"7z compression failed: {result.stderr}")
+        finally:
+            list_file_path.unlink(missing_ok=True)
         return
 
+    # Use zipfile (ZIPPER_TYPE == "zip" or fallback)
     from zipfile import ZIP_DEFLATED, ZIP_STORED, ZipFile
 
     zip_path.parent.mkdir(parents=True, exist_ok=True)
@@ -227,7 +253,9 @@ def expand_sequence(zip_path: Path, seq_state: dict) -> None:
         shutil.rmtree(target_dir)
     target_dir.mkdir(parents=True, exist_ok=True)
 
-    if USE_7Z and SEVEN_Z_EXE:
+    if ZIPPER_TYPE == "7z":
+        if SEVEN_Z_EXE is None:
+            raise RuntimeError("7z extraction requested but 7z executable not found in PATH")
         cmd = [
             SEVEN_Z_EXE,
             "x",