Expose node shard capacity limits

tests/test_tracker_routing.py

@@ -864,6 +864,63 @@ def test_tracker_registration_rejects_invalid_max_loaded_shards():
         tracker.stop()
 
 
+def test_network_map_exposes_node_capacity_limits():
+    tracker = TrackerServer(model_presets={
+        "tiny-model": {
+            "total_layers": 12,
+            "bytes_per_layer": {"bfloat16": 1_000},
+        },
+    })
+    tracker_port = tracker.start()
+    try:
+        _post_json(
+            f"http://127.0.0.1:{tracker_port}/v1/nodes/register",
+            {"endpoint": "http://127.0.0.1:9021", "model": "tiny-model",
+             "shard_start": 0, "shard_end": 7,
+             "vram_bytes": 10_000, "ram_bytes": 20_000, "max_loaded_shards": 2,
+             "quantizations": ["bfloat16"], "benchmark_tokens_per_sec": 4.0,
+             "hardware_profile": {}, "score": 1.0},
+        )
+
+        network_map = _get_json(f"http://127.0.0.1:{tracker_port}/v1/network/map")
+
+        node = network_map["nodes"][0]
+        assert node["capacity"]["vram_bytes"] == 10_000
+        assert node["capacity"]["ram_bytes"] == 20_000
+        assert node["capacity"]["max_loaded_shards"] == 2
+        assert node["capacity"]["max_assignable_layers"] == 8
+        assert node["capacity"]["benchmark_tokens_per_sec"] == 4.0
+    finally:
+        tracker.stop()
+
+
+def test_rebalance_keeps_one_active_range_even_when_multiple_slots_advertised():
+    """max_loaded_shards is exposed but reserved until node runtime supports multi-range serving."""
+    tracker = TrackerServer(model_presets={
+        "tiny-model": {
+            "total_layers": 8,
+            "bytes_per_layer": {"bfloat16": 1_000},
+        },
+    })
+    tracker_port = tracker.start()
+    try:
+        reg = _post_json(
+            f"http://127.0.0.1:{tracker_port}/v1/nodes/register",
+            {"endpoint": "http://127.0.0.1:9022", "model": "tiny-model",
+             "vram_bytes": 20_000, "ram_bytes": 20_000, "max_loaded_shards": 2,
+             "quantizations": ["bfloat16"], "benchmark_tokens_per_sec": 1.0,
+             "hardware_profile": {}, "score": 1.0},
+        )
+
+        assert reg["directive"]["action"] == "LOAD_SHARD"
+        assert reg["directive"]["start_layer"] == 0
+        assert reg["directive"]["end_layer"] == 7
+        hb = _post_json(f"http://127.0.0.1:{tracker_port}/v1/nodes/{reg['node_id']}/heartbeat", {})
+        assert hb == {}
+    finally:
+        tracker.stop()
+
+
 def test_tracker_routes_only_nodes_for_requested_model():
     """A node registered for one model cannot satisfy another model's route."""
     tracker = TrackerServer(model_presets={