diff --git a/tests/test_web_observability.py b/tests/test_web_observability.py
index 4ce29d37..76746238 100644
--- a/tests/test_web_observability.py
+++ b/tests/test_web_observability.py
@@ -2298,6 +2298,32 @@ def test_scan_terminal_timeout_does_not_replace_better_cached_snapshot(monkeypat
     assert [row["id"] for row in cached["rows"]] == ["old-1", "old-2"]
 
 
+def test_scan_terminal_prewarm_builds_default_terminal_payload(monkeypatch):
+    calls = []
+
+    def _fake_build(filters, *, force_refresh=False):
+        calls.append((dict(filters), force_refresh))
+        return {"rows": []}
+
+    monkeypatch.setattr(
+        scan_terminal_service,
+        "_build_scan_terminal_payload_uncached",
+        _fake_build,
+    )
+
+    assert scan_terminal_service._warm_scan_terminal_payloads() == 1
+    filters, force_refresh = calls[0]
+    assert force_refresh is False
+    assert filters["scan_mode"] == "tradable"
+    assert filters["min_price"] == 0.05
+    assert filters["max_price"] == 0.95
+    assert filters["min_edge_pct"] == 2.0
+    assert filters["min_liquidity"] == 500.0
+    assert filters["market_type"] == "maxtemp"
+    assert filters["time_range"] == "today"
+    assert filters["limit"] == 180
+
+
 def test_scan_terminal_service_returns_failed_without_success_snapshot(monkeypatch):
     filters = {"scan_mode": "tradable", "limit": 5}
     scan_terminal_cache._SCAN_TERMINAL_CACHE.clear()
diff --git a/web/scan_terminal_service.py b/web/scan_terminal_service.py
index 730a3bb8..e713e826 100644
--- a/web/scan_terminal_service.py
+++ b/web/scan_terminal_service.py
@@ -336,6 +336,36 @@ def build_scan_terminal_payload(
 
 _SCAN_PREWARM_STARTED = False
 _SCAN_PREWARM_LOCK = threading.Lock()
+_SCAN_TERMINAL_PREWARM_RAW_FILTERS = [
+    {
+        "scan_mode": "tradable",
+        "min_price": 0.05,
+        "max_price": 0.95,
+        "min_edge_pct": 2,
+        "min_liquidity": 500,
+        "market_type": "maxtemp",
+        "time_range": "today",
+        "limit": 180,
+    }
+]
+
+
+def _scan_terminal_prewarm_filters() -> List[Dict[str, Any]]:
+    return [
+        _normalize_scan_terminal_filters(filters)
+        for filters in _SCAN_TERMINAL_PREWARM_RAW_FILTERS
+    ]
+
+
+def _warm_scan_terminal_payloads() -> int:
+    ok = 0
+    for filters in _scan_terminal_prewarm_filters():
+        try:
+            _build_scan_terminal_payload_uncached(filters, force_refresh=False)
+            ok += 1
+        except Exception as exc:
+            logger.warning("scan terminal payload pre-warm failed: {}", exc)
+    return ok
 
 
 def start_scan_terminal_prewarm() -> None:
@@ -379,11 +409,13 @@ def start_scan_terminal_prewarm() -> None:
                         ok += 1
                     except Exception:
                         pass
+            payload_ok = _warm_scan_terminal_payloads()
             elapsed = int(time.time() - started)
             logger.info(
-                "scan terminal pre-warm finished ok={}/{} elapsed={}s",
+                "scan terminal pre-warm finished ok={}/{} payloads={} elapsed={}s",
                 ok,
                 len(city_names),
+                payload_ok,
                 elapsed,
             )
         except (ValueError, OSError, IOError):