fix: validate scraper metric semantics

tests/test_scraper_semantics.py

@@ -0,0 +1,28 @@
+from scrapers import lookintobitcoin
+from scoring import engine
+
+
+def test_hash_ribbon_signal_requires_a_current_truthy_marker():
+    named_but_inactive = {"name": "Buy Signal", "y": [1, None, None]}
+    active = {"name": "Buy Signal", "y": [None, 0, 1]}
+
+    assert lookintobitcoin._trace_signal_is_active(named_but_inactive) is False
+    assert lookintobitcoin._trace_signal_is_active(active) is True
+
+
+def test_lth_supply_trace_selection_never_falls_back_to_price():
+    traces = [
+        {"name": "BTC Price", "y": [60000, 61000]},
+        {"name": "Long-Term Holder Supply", "y": [14_000_000, 14_100_000]},
+    ]
+
+    assert lookintobitcoin._find_lth_supply_trace(traces)["name"] == "Long-Term Holder Supply"
+    assert lookintobitcoin._find_lth_supply_trace(traces[:1]) is None
+
+
+def test_vdd_derived_return_is_labeled_as_momentum_not_raw_multiple():
+    result = engine.score_all({"vdd_multiple": {"value": 0.12}})
+    vdd = next(metric for metric in result["metrics"] if metric["key"] == "vdd_multiple")
+
+    assert vdd["name"] == "VDD 30-Period Momentum"
+    assert vdd["transform"] == "30_period_return"