Add SSI disability criteria input (#8398)

* Add SSA disability screen input

* Document SSI disability transition precedence

* Remove SSA disability screen alias

* Carry data-backed SSI disability criteria forward

Author: MaxGhenis

changelog.d/added/ssa-disability-screen.md

@@ -0,0 +1 @@
+Added an SSA disability-screen variable for data-backed SSI disability modeling.

changelog.d/fixed/ssi-disability-sga.md

@@ -1 +1 @@
-Keep the SSI substantial gainful activity screen separate from the data-backed SSI disability criteria variable.
+Keep the SSI substantial gainful activity screen separate from the data-backed SSI disability criteria variable and preserve data-backed SSI disability criteria across future analysis years.

policyengine_us/tests/core/test_ssi_disability_criteria_inputs.py

@@ -0,0 +1,36 @@
+from policyengine_us import Simulation
+
+
+def test_data_provided_ssi_disability_criteria_carries_to_future_years():
+    simulation = Simulation(
+        situation={
+            "people": {
+                "person1": {
+                    "is_disabled": {2024: False, 2026: False},
+                    "meets_ssi_disability_criteria": {2024: True},
+                }
+            }
+        }
+    )
+
+    result = simulation.calculate("meets_ssi_disability_criteria", 2026)
+
+    assert result[0]
+
+
+def test_formula_derived_ssi_disability_criteria_allows_later_disabled_input():
+    simulation = Simulation(
+        situation={
+            "people": {
+                "person1": {
+                    "is_disabled": {2024: False, 2026: True},
+                }
+            }
+        }
+    )
+
+    assert not simulation.calculate("meets_ssi_disability_criteria", 2024)[0]
+
+    result = simulation.calculate("meets_ssi_disability_criteria", 2026)
+
+    assert result[0]

policyengine_us/tests/policy/baseline/gov/ssa/ssi/meets_ssi_disability_criteria.yaml

@@ -21,3 +21,19 @@
     ssi_engaged_in_sga: false
   output:
     meets_ssi_disability_criteria: false
+
+- name: Data-provided SSI disability criteria can override broad disability
+  period: 2024
+  input:
+    meets_ssi_disability_criteria: true
+    is_disabled: false
+  output:
+    meets_ssi_disability_criteria: true
+
+- name: Data-provided SSI disability criteria can exclude broad disability
+  period: 2024
+  input:
+    meets_ssi_disability_criteria: false
+    is_disabled: true
+  output:
+    meets_ssi_disability_criteria: false

policyengine_us/variables/gov/ssa/ssi/eligibility/status/meets_ssi_disability_criteria.py

@@ -13,4 +13,23 @@ class meets_ssi_disability_criteria(Variable):
     reference = "https://www.law.cornell.edu/uscode/text/42/1382c#a_3_A"
 
     def formula(person, period, parameters):
+        holder = person.simulation.get_holder("meets_ssi_disability_criteria")
+        prior_periods = [
+            known_period
+            for known_period in holder.get_known_periods()
+            if known_period.unit == YEAR and known_period.start < period.start
+        ]
+        if prior_periods:
+            latest_period = max(
+                prior_periods, key=lambda known_period: known_period.start
+            )
+            latest_value = holder.get_array(
+                latest_period, person.simulation.branch_name
+            )
+            latest_broad_disability = person("is_disabled", latest_period)
+            # Data-backed overrides should persist across analysis years; pure
+            # formula caches should not shadow later is_disabled inputs.
+            if not np.array_equal(latest_value, latest_broad_disability):
+                return None
+
         return person("is_disabled", period)