Fix meshnet-node model and shard flag parsing.

Unify --model and --model-id so catalog names use the tracker path, and allow --shard-start/--shard-end with --model instead of requiring --model-id.

Co-authored-by: Cursor <cursoragent@cursor.com>

tests/test_node_startup.py

@@ -1603,6 +1603,47 @@ def test_preset_model_startup_starts_heartbeat(tmp_path, monkeypatch):
         tracker.stop()
 
 
+def test_preset_model_startup_honors_pinned_shard_range(tmp_path, monkeypatch):
+    """Explicit --shard-start/--shard-end override tracker auto-assignment."""
+    import meshnet_node.startup as startup_mod
+
+    monkeypatch.setattr(
+        startup_mod,
+        "detect_hardware",
+        lambda: {"device": "cpu", "gpu_name": None, "vram_mb": 0, "ram_mb": 16 * 1024},
+    )
+    heartbeat_calls = []
+    monkeypatch.setattr(
+        startup_mod,
+        "_start_heartbeat",
+        lambda *args, **kwargs: heartbeat_calls.append((args, kwargs)),
+    )
+
+    tracker = TrackerServer(model_presets={"stub-model": {"layers_start": 0, "layers_end": 15}})
+    tracker_port = tracker.start()
+    tracker_url = f"http://127.0.0.1:{tracker_port}"
+    try:
+        node = run_startup(
+            tracker_url=tracker_url,
+            model="stub-model",
+            shard_start=0,
+            shard_end=5,
+            wallet_path=tmp_path / "wallet.json",
+            cache_dir=tmp_path / "shards",
+        )
+        try:
+            assert len(heartbeat_calls) == 1
+            args, kwargs = heartbeat_calls[0]
+            reg_payload = args[2]
+            assert reg_payload["shard_start"] == 0
+            assert reg_payload["shard_end"] == 5
+            assert reg_payload["managed_assignment"] is False
+        finally:
+            node.stop()
+    finally:
+        tracker.stop()
+
+
 def test_real_model_startup_registers_downloaded_inventory_without_checksum(
     tmp_path,
     monkeypatch,