diff --git a/domain/property_baseline/calculator_rebaseliner.py b/domain/property_baseline/calculator_rebaseliner.py
index 184f56b0..9c412c4e 100644
--- a/domain/property_baseline/calculator_rebaseliner.py
+++ b/domain/property_baseline/calculator_rebaseliner.py
@@ -12,12 +12,19 @@ if TYPE_CHECKING:
 
 logger = logging.getLogger(__name__)
 
-# The calculator targets SAP 10.2 (14-03-2025). A cert lodged below this carries
-# a superseded methodology and is rebaselined to the calculator's output; at or
-# above it, the API's lodged figures are kept and the calculator only validates.
-_SAP10_2_FLOOR = 10.2
-_SAP_ABS_TOL = 0.5
-_REL_TOL = 0.01
+# Lodged figures are trusted from SAP 10.2 (14-03-2025) onward — the version the
+# calculator targets. A cert lodged below this carries a superseded methodology,
+# so the calculator's output replaces it; at or above it the lodged figures are
+# kept and the calculator only validates against them.
+_MIN_TRUSTED_SAP_VERSION = 10.2
+
+# Divergence thresholds for that validation log. The calculator emits a
+# *continuous* SAP score whereas the lodged score is rounded to an integer, so a
+# gap up to half a point is just rounding — beyond it the calculator and the
+# register genuinely disagree and we record it. CO2 and Primary Energy Intensity
+# are not rounded that way, so they get a 1% relative band instead.
+_MAX_SAP_SCORE_DIVERGENCE = 0.5
+_MAX_RELATIVE_DIVERGENCE = 0.01
 _KG_PER_TONNE = 1000.0
 
 
@@ -49,7 +56,7 @@ class CalculatorRebaseliner(Rebaseliner):
         # load-bearing, so the batch aborts and the cert is fixed at once.
         result: SapResult = self._calculator.calculate(effective_epc)
         sap_version: Optional[float] = effective_epc.sap_version
-        if sap_version is not None and sap_version < _SAP10_2_FLOOR:
+        if sap_version is not None and sap_version < _MIN_TRUSTED_SAP_VERSION:
             return Performance.from_sap_result(result), "pre_sap10"
         self._log_divergence(
             property_id=property_id, sap_version=sap_version, result=result, lodged=lodged
@@ -64,15 +71,15 @@ class CalculatorRebaseliner(Rebaseliner):
         result: "SapResult",
         lodged: Performance,
     ) -> None:
-        if abs(result.sap_score_continuous - lodged.sap_score) > _SAP_ABS_TOL:
+        if abs(result.sap_score_continuous - lodged.sap_score) > _MAX_SAP_SCORE_DIVERGENCE:
             self._warn(property_id, sap_version, "sap_score", lodged.sap_score, result.sap_score_continuous)
-        if _relative_diff(result.primary_energy_kwh_per_m2, lodged.primary_energy_intensity) > _REL_TOL:
+        if _relative_diff(result.primary_energy_kwh_per_m2, lodged.primary_energy_intensity) > _MAX_RELATIVE_DIVERGENCE:
             self._warn(
                 property_id, sap_version, "primary_energy_intensity",
                 lodged.primary_energy_intensity, result.primary_energy_kwh_per_m2,
             )
         calculated_co2_t = result.co2_kg_per_yr / _KG_PER_TONNE
-        if _relative_diff(calculated_co2_t, lodged.co2_emissions) > _REL_TOL:
+        if _relative_diff(calculated_co2_t, lodged.co2_emissions) > _MAX_RELATIVE_DIVERGENCE:
             self._warn(property_id, sap_version, "co2_emissions", lodged.co2_emissions, calculated_co2_t)
 
     def _warn(