diff --git a/packages/tracker/meshnet_tracker/model_files.py b/packages/tracker/meshnet_tracker/model_files.py
index 4e97a49..70cc503 100644
--- a/packages/tracker/meshnet_tracker/model_files.py
+++ b/packages/tracker/meshnet_tracker/model_files.py
@@ -99,9 +99,18 @@ def select_safetensors_files_for_layers(
         if not isinstance(tensor_name, str) or not isinstance(rel_file, str):
             continue
         if _tensor_belongs_to_range(tensor_name, start_layer, end_layer, inferred_total_layers):
-            selected.add(_normalise_relative_file(rel_file))
+            rel = _normalise_relative_file(rel_file)
+            if not (root / rel).is_file():
+                # A required weight file is missing from this local snapshot: the
+                # snapshot is incomplete for this layer range, so it must not be
+                # advertised as a source at all. Silently dropping just this file
+                # (as before) made a partial snapshot look "fully cached" to
+                # downstream clients, which then skipped the real download and
+                # only discovered the missing weights at model-load time.
+                return []
+            selected.add(rel)
 
-    return sorted(rel for rel in selected if (root / rel).is_file())
+    return sorted(selected)
 
 
 def _tensor_belongs_to_range(
diff --git a/tests/test_tracker_model_files.py b/tests/test_tracker_model_files.py
new file mode 100644
index 0000000..bc7cfe9
--- /dev/null
+++ b/tests/test_tracker_model_files.py
@@ -0,0 +1,71 @@
+"""Tests for tracker-side layer-aware SafeTensors file selection.
+
+The tracker advertises its local snapshot as a downloadable "model source" for
+whatever layer range a node needs. If a required weight file for that range is
+missing from the tracker's own disk, the tracker must refuse to advertise
+itself as a source for that range — not quietly report the subset of files it
+does have as if that were the complete, correct set. A partial-but-"complete"
+answer makes the requesting node believe the download is already satisfied,
+so it never fetches the real weights and only discovers the gap much later
+at model-load time.
+"""
+
+import json
+
+from meshnet_tracker.model_files import select_safetensors_files_for_layers
+
+
+def _write_index(tmp_path, *, config=None):
+    (tmp_path / "config.json").write_text(
+        json.dumps(config or {"num_hidden_layers": 5}),
+        encoding="utf-8",
+    )
+    (tmp_path / "model.safetensors.index.json").write_text(
+        json.dumps({
+            "weight_map": {
+                "model.embed_tokens.weight": "model-00001-of-00004.safetensors",
+                "model.layers.0.self_attn.q_proj.weight": "model-00001-of-00004.safetensors",
+                "model.layers.4.self_attn.q_proj.weight": "model-00004-of-00004.safetensors",
+                "model.norm.weight": "model-00004-of-00004.safetensors",
+                "lm_head.weight": "model-00004-of-00004.safetensors",
+            },
+        }),
+        encoding="utf-8",
+    )
+
+
+def _touch(path, size=1):
+    path.write_bytes(b"0" * size)
+
+
+def test_selects_files_when_snapshot_is_complete(tmp_path):
+    "Selects files when snapshot is complete\n\nTags: general"
+    _write_index(tmp_path)
+    _touch(tmp_path / "model-00001-of-00004.safetensors")
+
+    files = select_safetensors_files_for_layers(tmp_path, 0, 0)
+
+    assert files == ["config.json", "model-00001-of-00004.safetensors", "model.safetensors.index.json"]
+
+
+def test_returns_empty_when_a_required_weight_file_is_missing_on_disk(tmp_path):
+    "Returns empty when a required weight file is missing on disk\n\nTags: general"
+    _write_index(tmp_path)
+    # model-00001-of-00004.safetensors is required for layer 0 but was never
+    # downloaded onto this tracker host — the snapshot is incomplete.
+
+    files = select_safetensors_files_for_layers(tmp_path, 0, 0)
+
+    assert files == []
+
+
+def test_tail_range_returns_empty_when_only_head_shard_present(tmp_path):
+    "Tail range returns empty when only head shard present\n\nTags: general"
+    _write_index(tmp_path)
+    _touch(tmp_path / "model-00001-of-00004.safetensors")
+    # model-00004-of-00004.safetensors (norm/lm_head) is required for the tail
+    # range but missing — must not be silently dropped from the result.
+
+    files = select_safetensors_files_for_layers(tmp_path, 4, 4)
+
+    assert files == []