Default online backtest to production GTL

app/services/backtest_service.py

@@ -176,8 +176,17 @@ SR_RESEARCH_VARIANTS = {
 
 
 def _sr_research_variant() -> str:
-    """S/R policy arm for local research; never read by the live scanner."""
-    value = os.getenv("BACKTEST_SR_VARIANT", "rewrite").strip().lower()
+    """Backtest target policy; research arms require an explicit override.
+
+    The unconfigured online/scheduled backtest must replay the same transient
+    Gate Target Ladder as the live scanner. Clean Structural S/R remains an
+    opt-in research arm here because it is intentionally chart/alert structure,
+    not the production gate's target source.
+    """
+    value = os.getenv(
+        "BACKTEST_SR_VARIANT",
+        EXPLICIT_TARGET_LADDER_VARIANT,
+    ).strip().lower()
     if value not in SR_RESEARCH_VARIANTS:
         allowed = ", ".join(sorted(SR_RESEARCH_VARIANTS))
         raise ValueError(f"Unknown BACKTEST_SR_VARIANT={value!r}; expected one of {allowed}")