diff --git a/core/download/aria2_backend.py b/core/download/aria2_backend.py
index b18651a..e8ac97d 100644
--- a/core/download/aria2_backend.py
+++ b/core/download/aria2_backend.py
@@ -4,6 +4,7 @@ import socket
 from typing import Any, Dict, Optional
 
 from ..log_system import create_module_logger
+from .dependencies import require_download_dependencies
 from .state import create_initial_progress
 
 log = create_module_logger("core.downloader")
@@ -13,16 +14,9 @@ class Aria2Error(RuntimeError):
     """Raised when the aria2 backend cannot start or process a request."""
 
 
-def _require_dependencies(dependencies: Any) -> Any:
-    """Return explicitly supplied services for the aria2 backend."""
-    if dependencies is None:
-        raise RuntimeError("aria2 backend dependencies were not provided")
-    return dependencies
-
-
 def try_certifi_ca_path(*, dependencies: Any = None) -> str:
     """Return certifi's CA bundle path when it is available."""
-    facade = _require_dependencies(dependencies)
+    facade = require_download_dependencies(dependencies, "aria2 backend")
     try:
         import certifi  # type: ignore
 
@@ -38,7 +32,7 @@ def resolve_aria2c_executable(
     dependencies: Any = None,
 ) -> str:
     """Resolve aria2c while restricting explicit paths to the managed install."""
-    facade = _require_dependencies(dependencies)
+    facade = require_download_dependencies(dependencies, "aria2 backend")
     active_settings = (
         settings if isinstance(settings, dict) else facade.load_settings()
     )
@@ -121,7 +115,7 @@ def delete_partial_download_files(
     dependencies: Any = None,
 ) -> None:
     """Delete an incomplete model and its aria2 control sidecar."""
-    facade = _require_dependencies(dependencies)
+    facade = require_download_dependencies(dependencies, "aria2 backend")
     for path in (dest_path, f"{dest_path}.aria2"):
         try:
             if path and facade.os.path.exists(path):
@@ -136,7 +130,7 @@ def delete_python_partial_download_file(
     dependencies: Any = None,
 ) -> None:
     """Remove a partial Python download without touching the final model path."""
-    facade = _require_dependencies(dependencies)
+    facade = require_download_dependencies(dependencies, "aria2 backend")
     try:
         if partial_path and facade.os.path.exists(partial_path):
             facade.os.remove(partial_path)
@@ -153,7 +147,7 @@ def delete_xet_partial_file(
     dependencies: Any = None,
 ) -> bool:
     """Delete a stopped Xet partial file, retrying while Windows releases it."""
-    facade = _require_dependencies(dependencies)
+    facade = require_download_dependencies(dependencies, "aria2 backend")
     attempts = max(1, int(attempts or 1))
     last_error: Optional[Exception] = None
     for attempt in range(attempts):
@@ -188,7 +182,7 @@ def resolve_download_url_for_aria2(
     dependencies: Any = None,
 ) -> tuple[str, Dict[str, str]]:
     """Preflight an aria2 URL and validate every redirect before RPC handoff."""
-    facade = _require_dependencies(dependencies)
+    facade = require_download_dependencies(dependencies, "aria2 backend")
     request_headers = facade.build_download_headers(url, headers)
     source_host = facade.urlparse(str(url or "")).hostname
     is_huggingface_source = facade.host_matches_domain(
@@ -221,7 +215,7 @@ def resolve_download_url_for_aria2(
 
 def read_aria2_version(executable: str, *, dependencies: Any = None) -> str:
     """Read the installed aria2 version without raising process errors."""
-    facade = _require_dependencies(dependencies)
+    facade = require_download_dependencies(dependencies, "aria2 backend")
     if not executable:
         return ""
     try:
@@ -265,7 +259,7 @@ def get_aria2_status(
     dependencies: Any = None,
 ) -> Dict[str, Any]:
     """Return aria2 availability, daemon and active-transfer information."""
-    facade = _require_dependencies(dependencies)
+    facade = require_download_dependencies(dependencies, "aria2 backend")
     active_settings = (
         settings if isinstance(settings, dict) else facade.load_settings()
     )
@@ -317,7 +311,7 @@ def aria2_rpc(
     dependencies: Any = None,
 ) -> Any:
     """Call the local aria2 JSON-RPC endpoint."""
-    facade = _require_dependencies(dependencies)
+    facade = require_download_dependencies(dependencies, "aria2 backend")
     if not facade.aria2_rpc_url:
         raise Aria2Error("aria2 RPC endpoint is not initialized")
 
@@ -356,7 +350,7 @@ def aria2_rpc(
 
 def aria2_ping(*, dependencies: Any = None) -> bool:
     """Check whether the local aria2 RPC endpoint responds."""
-    facade = _require_dependencies(dependencies)
+    facade = require_download_dependencies(dependencies, "aria2 backend")
     try:
         result = facade._aria2_rpc(
             "aria2.getVersion",
@@ -369,7 +363,7 @@ def aria2_ping(*, dependencies: Any = None) -> bool:
 
 def cancel_aria2_idle_timer_locked(*, dependencies: Any = None) -> None:
     """Cancel the pending idle timer while holding the aria2 lock."""
-    facade = _require_dependencies(dependencies)
+    facade = require_download_dependencies(dependencies, "aria2 backend")
     if facade.aria2_idle_timer is not None:
         facade.aria2_idle_timer.cancel()
         facade.aria2_idle_timer = None
@@ -377,7 +371,7 @@ def cancel_aria2_idle_timer_locked(*, dependencies: Any = None) -> None:
 
 def aria2_has_active_transfers_locked(*, dependencies: Any = None) -> bool:
     """Return whether aria2 has active resolver-owned transfers."""
-    facade = _require_dependencies(dependencies)
+    facade = require_download_dependencies(dependencies, "aria2 backend")
     return bool(facade.aria2_transfers)
 
 
@@ -387,7 +381,7 @@ def stop_aria2_daemon(
     dependencies: Any = None,
 ) -> Dict[str, Any]:
     """Stop the aria2 RPC process started by Model Resolver."""
-    facade = _require_dependencies(dependencies)
+    facade = require_download_dependencies(dependencies, "aria2 backend")
     with facade.aria2_lock:
         facade._cancel_aria2_idle_timer_locked()
         process = facade.aria2_process
@@ -442,7 +436,7 @@ def start_aria2_daemon(
     dependencies: Any = None,
 ) -> Dict[str, Any]:
     """Start the aria2 RPC process without creating a download."""
-    facade = _require_dependencies(dependencies)
+    facade = require_download_dependencies(dependencies, "aria2 backend")
     active_settings = (
         settings if isinstance(settings, dict) else facade.load_settings()
     )
@@ -476,7 +470,7 @@ def start_aria2_daemon(
 
 def aria2_idle_stop_worker(*, dependencies: Any = None) -> None:
     """Stop a resolver-owned daemon after its idle timeout."""
-    facade = _require_dependencies(dependencies)
+    facade = require_download_dependencies(dependencies, "aria2 backend")
     with facade.aria2_lock:
         facade.aria2_idle_timer = None
 
@@ -497,7 +491,7 @@ def aria2_idle_stop_worker(*, dependencies: Any = None) -> None:
 
 def schedule_aria2_idle_stop(*, dependencies: Any = None) -> None:
     """Schedule daemon shutdown when no resolver transfer remains active."""
-    facade = _require_dependencies(dependencies)
+    facade = require_download_dependencies(dependencies, "aria2 backend")
     settings = facade.load_settings()
     if not settings.get("aria2_auto_stop_daemon", True):
         return
@@ -525,7 +519,7 @@ def ensure_aria2_daemon(
     dependencies: Any = None,
 ) -> None:
     """Start or reuse the resolver-owned aria2 daemon."""
-    facade = _require_dependencies(dependencies)
+    facade = require_download_dependencies(dependencies, "aria2 backend")
     active_settings = (
         settings if isinstance(settings, dict) else facade.load_settings()
     )
@@ -624,7 +618,7 @@ def recover_aria2_missing_control_file(
     dependencies: Any = None,
 ) -> bool:
     """Restart a stale resolver daemon when a download loses its control file."""
-    facade = _require_dependencies(dependencies)
+    facade = require_download_dependencies(dependencies, "aria2 backend")
     with facade.aria2_lock:
         other_transfers = [
             active_id
@@ -670,7 +664,7 @@ def recover_aria2_missing_control_file(
 
 def aria2_tell_status(gid: str, *, dependencies: Any = None) -> Dict[str, Any]:
     """Read an aria2 transfer status with retries for transient resets."""
-    facade = _require_dependencies(dependencies)
+    facade = require_download_dependencies(dependencies, "aria2 backend")
     keys = [
         "gid",
         "status",
@@ -711,7 +705,7 @@ def download_file_with_aria2(
     dependencies: Any = None,
 ) -> Dict[str, Any]:
     """Download a file with an aria2c JSON-RPC process."""
-    facade = _require_dependencies(dependencies)
+    facade = require_download_dependencies(dependencies, "aria2 backend")
     settings = facade.load_settings()
     result = {
         "success": False,
@@ -1025,7 +1019,7 @@ def force_remove_aria2_transfer(
     dependencies: Any = None,
 ) -> None:
     """Request removal of an active aria2 transfer."""
-    facade = _require_dependencies(dependencies)
+    facade = require_download_dependencies(dependencies, "aria2 backend")
     try:
         facade._aria2_rpc(
             "aria2.forceRemove",
@@ -1041,7 +1035,7 @@ def get_aria2_action_lock(
     dependencies: Any = None,
 ) -> Any:
     """Return the per-download lock used to serialize aria2 actions."""
-    facade = _require_dependencies(dependencies)
+    facade = require_download_dependencies(dependencies, "aria2 backend")
     with facade.aria2_lock:
         lock = facade.aria2_action_locks.get(download_id)
         if lock is None:
@@ -1058,7 +1052,7 @@ def set_download_progress_status(
     **updates: Any,
 ) -> None:
     """Update a download status while holding the progress lock."""
-    facade = _require_dependencies(dependencies)
+    facade = require_download_dependencies(dependencies, "aria2 backend")
     with facade.download_lock:
         if download_id in facade.download_progress:
             facade.download_progress[download_id]["status"] = status
@@ -1071,7 +1065,7 @@ def run_aria2_desired_state_worker(
     dependencies: Any = None,
 ) -> None:
     """Apply the latest queued pause/resume request for a transfer."""
-    facade = _require_dependencies(dependencies)
+    facade = require_download_dependencies(dependencies, "aria2 backend")
     while True:
         with facade.aria2_lock:
             desired = dict(facade.aria2_desired_states.get(download_id) or {})
@@ -1152,7 +1146,7 @@ def queue_aria2_desired_state(
     dependencies: Any = None,
 ) -> Dict[str, Any]:
     """Queue an aria2 pause/resume state change and start its worker."""
-    facade = _require_dependencies(dependencies)
+    facade = require_download_dependencies(dependencies, "aria2 backend")
     transfer = facade.aria2_transfers.get(download_id)
     if not transfer or not transfer.get("gid"):
         return {"success": False, "error": "Download action is not available yet"}
@@ -1193,7 +1187,7 @@ def _set_aria2_desired_download_state(
     *,
     dependencies: Any = None,
 ) -> Dict[str, Any]:
-    facade = _require_dependencies(dependencies)
+    facade = require_download_dependencies(dependencies, "aria2 backend")
     if download_id in facade.cancelled_downloads:
         return {"success": False, "error": "Download is being cancelled"}
     return facade._queue_aria2_desired_state(
diff --git a/core/download/config.py b/core/download/config.py
index 57cc14a..f85cf04 100644
--- a/core/download/config.py
+++ b/core/download/config.py
@@ -3,12 +3,7 @@
 import uuid
 from typing import Any, Dict, Optional
 
-
-def _require_dependencies(dependencies: Any) -> Any:
-    """Return explicitly supplied settings services."""
-    if dependencies is None:
-        raise RuntimeError("download configuration dependencies were not provided")
-    return dependencies
+from .dependencies import require_download_dependencies
 
 
 def generate_download_id() -> str:
@@ -22,6 +17,6 @@ def download_backend_from_settings(
     dependencies: Any = None,
 ) -> str:
     """Return the normalized backend selected in the active settings."""
-    facade = _require_dependencies(dependencies)
+    facade = require_download_dependencies(dependencies, "download configuration")
     active_settings = settings if isinstance(settings, dict) else facade.load_settings()
     return facade.normalize_download_backend(active_settings.get("download_backend"))
diff --git a/core/download/dependencies.py b/core/download/dependencies.py
new file mode 100644
index 0000000..a70bc4c
--- /dev/null
+++ b/core/download/dependencies.py
@@ -0,0 +1,10 @@
+"""Shared dependency validation for download components."""
+
+from typing import Any
+
+
+def require_download_dependencies(dependencies: Any, component: str) -> Any:
+    """Return explicitly supplied services for a download component."""
+    if dependencies is None:
+        raise RuntimeError(f"{component} dependencies were not provided")
+    return dependencies
diff --git a/core/download/directories.py b/core/download/directories.py
index ea8a904..c4d43f3 100644
--- a/core/download/directories.py
+++ b/core/download/directories.py
@@ -3,12 +3,7 @@
 import os
 from typing import Any, List, Optional
 
-
-def _require_dependencies(dependencies: Any) -> Any:
-    """Return explicitly supplied services for directory resolution."""
-    if dependencies is None:
-        raise RuntimeError("download directory dependencies were not provided")
-    return dependencies
+from .dependencies import require_download_dependencies
 
 
 def get_download_directory(
@@ -18,7 +13,7 @@ def get_download_directory(
     dependencies: Any = None,
 ) -> Optional[str]:
     """Get the appropriate download directory for a model category."""
-    facade = _require_dependencies(dependencies)
+    facade = require_download_dependencies(dependencies, "download directory")
     folder_paths = facade.folder_paths
 
     if folder_paths is None:
diff --git a/core/download/huggingface_xet.py b/core/download/huggingface_xet.py
index af637a7..0790b2a 100644
--- a/core/download/huggingface_xet.py
+++ b/core/download/huggingface_xet.py
@@ -5,18 +5,12 @@ from typing import Any, Dict, Optional
 from urllib.parse import urlparse
 
 from ..log_system import create_module_logger
+from .dependencies import require_download_dependencies
 from .state import create_initial_progress
 
 log = create_module_logger("core.downloader")
 
 
-def _require_dependencies(dependencies: Any) -> Any:
-    """Return explicitly supplied services for Hugging Face Xet."""
-    if dependencies is None:
-        raise RuntimeError("Hugging Face Xet dependencies were not provided")
-    return dependencies
-
-
 class HuggingFaceXetDownloadCancelled(Exception):
     """Raised by the Xet progress adapter when a download is cancelled."""
 
@@ -32,7 +26,7 @@ class HuggingFaceXetProgressAdapter:
         *,
         dependencies: Any = None,
     ) -> None:
-        self.dependencies = _require_dependencies(dependencies)
+        self.dependencies = require_download_dependencies(dependencies, "Hugging Face Xet")
         self.download_id = download_id
         self.total_size = max(0, int(total_size or 0))
         self.downloaded = 0
@@ -165,7 +159,7 @@ def run_huggingface_xet_transfer(
     dependencies: Any = None,
 ) -> None:
     """Use detailed native Xet progress when supported, with legacy fallback."""
-    facade = _require_dependencies(dependencies)
+    facade = require_download_dependencies(dependencies, "Hugging Face Xet")
     import hf_xet
     from huggingface_hub.file_download import xet_get
     try:
@@ -279,7 +273,7 @@ def download_huggingface_xet(
     dependencies: Any = None,
 ) -> Optional[Dict[str, Any]]:
     """Download Hugging Face Xet files with the official hf_xet transport."""
-    facade = _require_dependencies(dependencies)
+    facade = require_download_dependencies(dependencies, "Hugging Face Xet")
     validated_url = facade.validate_public_http_url(url)
     parsed_url = urlparse(validated_url)
     if not (
diff --git a/core/download/metadata.py b/core/download/metadata.py
index f328343..5eef09c 100644
--- a/core/download/metadata.py
+++ b/core/download/metadata.py
@@ -23,6 +23,7 @@ from ..type_utils import (
     first_non_empty,
     normalize_category_to_model_type,
 )
+from .dependencies import require_download_dependencies
 from .validation import _is_sensitive_metadata_key, _strip_sensitive_url_params
 
 log = create_module_logger("core.downloader")
@@ -32,13 +33,6 @@ _as_list = as_list
 _first_present = first_non_empty
 
 
-def _require_dependencies(dependencies: Any) -> Any:
-    """Return explicitly supplied services for metadata sidecars."""
-    if dependencies is None:
-        raise RuntimeError("metadata sidecar dependencies were not provided")
-    return dependencies
-
-
 def write_model_resolver_metadata(
     dest_path: str,
     metadata: Optional[Dict[str, Any]] = None,
@@ -49,7 +43,7 @@ def write_model_resolver_metadata(
     dependencies: Any = None,
 ) -> Optional[str]:
     """Write metadata only to the sidecar owned by Model Resolver."""
-    facade = _require_dependencies(dependencies)
+    facade = require_download_dependencies(dependencies, "metadata sidecar")
     metadata_path = facade.get_model_resolver_sidecar_path(dest_path)
 
     try:
diff --git a/core/download/previews.py b/core/download/previews.py
index 3d9b04c..833e7a3 100644
--- a/core/download/previews.py
+++ b/core/download/previews.py
@@ -11,6 +11,7 @@ import requests
 from ..log_system import create_module_logger
 from ..path_utils import get_filename_from_path
 from ..type_utils import as_dict, as_list
+from .dependencies import require_download_dependencies
 
 log = create_module_logger("core.downloader")
 
@@ -35,13 +36,6 @@ MODEL_PREVIEW_EXTENSIONS = (
 )
 
 
-def _require_dependencies(dependencies: Any) -> Any:
-    """Return explicitly supplied services for preview downloads."""
-    if dependencies is None:
-        raise RuntimeError("preview download dependencies were not provided")
-    return dependencies
-
-
 def get_existing_model_preview_path(dest_path: str) -> str:
     """Return the first adjacent preview media file available for a model."""
     model_base_path, _model_ext = os.path.splitext(dest_path)
@@ -122,7 +116,7 @@ def _download_preview_asset(
     *,
     dependencies: Any = None,
 ) -> bytes:
-    facade = _require_dependencies(dependencies)
+    facade = require_download_dependencies(dependencies, "preview download")
     max_bytes = (
         MODEL_PREVIEW_VIDEO_MAX_DOWNLOAD_BYTES
         if media_type == "video"
@@ -200,7 +194,7 @@ def _download_preview_asset_with_system_trust(
         build_opener,
     )
 
-    facade = _require_dependencies(dependencies)
+    facade = require_download_dependencies(dependencies, "preview download")
     max_bytes = (
         MODEL_PREVIEW_VIDEO_MAX_DOWNLOAD_BYTES
         if media_type == "video"
@@ -362,7 +356,7 @@ def create_model_preview(
     dependencies: Any = None,
 ) -> str:
     """Create adjacent preview media using LoRA Manager-compatible behavior."""
-    dependencies = _require_dependencies(dependencies)
+    dependencies = require_download_dependencies(dependencies, "preview download")
     existing_path = get_existing_model_preview_path(dest_path)
     source = metadata if isinstance(metadata, dict) else {}
     preview_url, media_type = _first_model_preview_asset(source)
diff --git a/tests/test_download_dependencies.py b/tests/test_download_dependencies.py
new file mode 100644
index 0000000..9364ec3
--- /dev/null
+++ b/tests/test_download_dependencies.py
@@ -0,0 +1,27 @@
+import pytest
+
+from core.download.dependencies import require_download_dependencies
+
+
+@pytest.mark.parametrize(
+    ("require_dependencies", "message"),
+    [
+        (require_download_dependencies, "download configuration"),
+        (require_download_dependencies, "download directory"),
+        (require_download_dependencies, "metadata sidecar"),
+        (require_download_dependencies, "Hugging Face Xet"),
+        (require_download_dependencies, "aria2 backend"),
+        (require_download_dependencies, "preview download"),
+    ],
+)
+def test_download_dependency_guards_preserve_error_and_identity(
+    require_dependencies, message
+):
+    with pytest.raises(
+        RuntimeError,
+        match=rf"{message} dependencies were not provided",
+    ):
+        require_dependencies(None, message)
+
+    dependencies = object()
+    assert require_dependencies(dependencies, message) is dependencies