From d27eb2d9564bb5d19c4588b4a6ee69df66fad4c2 Mon Sep 17 00:00:00 2001
From: t-kramer <t.kramer@berkeley.edu>
Date: Mon, 14 Sep 2026 09:11:39 -0700
Subject: [PATCH] fix: minor adjustments to PR #180

---
 pages/emissions_page.py |  4 ++++
 src/config.py           |  2 +-
 src/emissions.py        | 24 ++++++++++++++++++++++--
 src/energy.py           |  8 ++------
 4 files changed, 29 insertions(+), 9 deletions(-)

diff --git a/pages/emissions_page.py b/pages/emissions_page.py
index d9e9e67..5157d39 100644
--- a/pages/emissions_page.py
+++ b/pages/emissions_page.py
@@ -310,6 +310,10 @@ def handle_emission_group_selection(group_id, metadata_data, selected_ids, store
             "year": default_year,
         }
     )
+    # If the base was a Constant scenario it may have no grid_scenario; restore a
+    # sensible default so Cambium-based group variants don't fail validation.
+    if not base_scenario.get("grid_scenario"):
+        base_scenario["grid_scenario"] = "MidCase"
 
     # Reset to default 2/3/4 scenarios (a, b, optionally c & d) with group-specific values
     updated_scenarios = []
diff --git a/src/config.py b/src/config.py
index f79c319..d839377 100644
--- a/src/config.py
+++ b/src/config.py
@@ -70,7 +70,7 @@ class EmissionScenarioDefaults(Enum):
     """Default values for emission scenario parameters."""
 
     ELEC_EMISSION_SOURCE: str = "Marginal (Cambium, Long-run)"
-    ELEC_AVG_EMISSION_RATE_G_KWH: float = None
+    ELEC_AVG_EMISSION_RATE_G_KWH: float | None = None
     YEAR: int = 2025
     REFRIGERANT_LEAKAGE: float = 0.02
     EMISSION_TYPE: str = "Includes pre-combustion"
diff --git a/src/emissions.py b/src/emissions.py
index dd286e8..fef0f2f 100644
--- a/src/emissions.py
+++ b/src/emissions.py
@@ -1,16 +1,28 @@
 from pathlib import Path
+from typing import Literal
 
 import pandas as pd
-from pydantic import BaseModel
+from pydantic import BaseModel, model_validator
 
 from src import paths
 from src.mixins import DotAccessMixin
 
+CAMBIUM_SOURCES = (
+    "Marginal (Cambium, Long-run)",
+    "Marginal (Cambium, Short-run)",
+    "Average (Cambium)",
+)
+
 
 class EmissionScenario(DotAccessMixin, BaseModel):
     em_scen_id: str
     em_scen_name: str
-    elec_emission_source: str
+    elec_emission_source: Literal[
+        "Marginal (Cambium, Long-run)",
+        "Marginal (Cambium, Short-run)",
+        "Average (Cambium)",
+        "Constant (User-provided)",
+    ]
     elec_avg_emission_rate_gCO2e_per_kWh: float | None = None
     grid_scenario: str | None = None
     gea_grid_region: str | None = None
@@ -19,6 +31,14 @@ class EmissionScenario(DotAccessMixin, BaseModel):
     ng_emission_rate_gCO2e_per_kWh: float
     year: int
 
+    @model_validator(mode="after")
+    def check_source_fields(self) -> "EmissionScenario":
+        if self.elec_emission_source in CAMBIUM_SOURCES and not self.grid_scenario:
+            raise ValueError(
+                f"grid_scenario is required for emission source '{self.elec_emission_source}'"
+            )
+        return self
+
 
 class StandardEmissions:
     """
diff --git a/src/energy.py b/src/energy.py
index cd85c28..c22eca5 100644
--- a/src/energy.py
+++ b/src/energy.py
@@ -2,7 +2,7 @@
 import pandas as pd
 
 from src.config import Columns as Col
-from src.emissions import get_emissions_data
+from src.emissions import CAMBIUM_SOURCES, get_emissions_data
 from src.equipment import Equipment, EquipmentLibrary, PerformanceCurves
 from src.loads import StandardLoad
 from src.metadata import Metadata
@@ -1161,11 +1161,7 @@ def site_to_source(
         base[Col.HOUR.value] = base.index.hour
         base[Col.DOY.value] = base.index.dayofyear
 
-        if em_scen.elec_emission_source in [
-            "Marginal (Cambium, Long-run)",
-            "Marginal (Cambium, Short-run)",
-            "Average (Cambium)",
-        ]:
+        if em_scen.elec_emission_source in CAMBIUM_SOURCES:
             emissions_data = get_emissions_data(metadata[em_scen_id])
             logger.debug(
                 f"Cambium grid emissions: Loaded {len(emissions_data.df)} emission data rows"