fix: isolate on-chain provider outages

tests/test_server_reliability.py

@@ -108,6 +108,21 @@ def test_partial_fast_scrape_preserves_last_known_good_metric(server, monkeypatc
     assert saved["fear_greed"]["source"] == "alternative.me"
 
 
+def test_onchain_sources_fail_independently(server, monkeypatch):
+    fake_lib = types.ModuleType("scrapers.lookintobitcoin")
+    setattr(fake_lib, "scrape_all", lambda: (_ for _ in ()).throw(RuntimeError("LIB down")))
+    fake_coc = types.ModuleType("scrapers.checkonchain")
+    setattr(fake_coc, "scrape_all", lambda: {"sopr": {"value": 0.99}})
+    monkeypatch.setitem(sys.modules, "scrapers.lookintobitcoin", fake_lib)
+    monkeypatch.setitem(sys.modules, "scrapers.checkonchain", fake_coc)
+
+    observations, errors, successful_sources = server._scrape_onchain_sources()
+
+    assert observations["sopr"]["value"] == 0.99
+    assert successful_sources == 1
+    assert any("LookIntoBitcoin" in error for error in errors)
+
+
 def test_expired_onchain_timestamp_triggers_real_refresh(server, monkeypatch, tmp_path):
     old = datetime.now(timezone.utc) - timedelta(hours=7)
     cache_path = tmp_path / "cache.json"