fix model load/unload

tests/test_node_startup.py

@@ -287,6 +287,47 @@ def test_configure_torch_threads_applies_explicit_settings(monkeypatch):
     assert active == {"torch_threads": 12, "torch_interop_threads": 2}
 
 
+def test_heartbeat_applies_release_without_reregistering(monkeypatch):
+    """DROP_SHARD has no replacement range and must not look like an outage."""
+    import meshnet_node.startup as startup_mod
+
+    released = threading.Event()
+    requests: list[tuple[str, dict]] = []
+
+    class FakeNode:
+        def apply_tracker_directives(self, directives):
+            assert directives == [{"action": "DROP_SHARD", "model": "Qwen/Qwen2.5-0.5B-Instruct"}]
+            return {"action": "DROP_SHARD", "model": "Qwen/Qwen2.5-0.5B-Instruct"}
+
+    def fake_post(url, payload, timeout=10.0):
+        requests.append((url, dict(payload)))
+        released.set()
+        return {"directives": [{"action": "DROP_SHARD", "model": "Qwen/Qwen2.5-0.5B-Instruct"}]}
+
+    sleep_calls = 0
+
+    def one_heartbeat(_seconds):
+        nonlocal sleep_calls
+        sleep_calls += 1
+        if sleep_calls > 1:
+            raise SystemExit
+
+    monkeypatch.setattr(startup_mod, "_post_json", fake_post)
+    monkeypatch.setattr(startup_mod.time, "sleep", one_heartbeat)
+    payload = {
+        "model": "Qwen2.5-0.5B-Instruct",
+        "hf_repo": "Qwen/Qwen2.5-0.5B-Instruct",
+        "shard_start": 0,
+        "shard_end": 23,
+    }
+    startup_mod._start_heartbeat("http://tracker", "node-1", payload, interval=0, node_ref=FakeNode())
+
+    assert released.wait(1), "heartbeat did not receive the queued release"
+    assert len(requests) == 1, "release must not trigger a re-registration"
+    assert payload["shard_start"] == 0
+    assert payload["shard_end"] == 23
+
+
 def test_benchmark_throughput_is_registered_in_payload(monkeypatch, tmp_path):
     "benchmark_tokens_per_sec from the benchmark is included in the tracker registration.\n\nTags: node, performance, startup"
     import meshnet_node.startup as startup_mod