refactor(evidence): unify formulas with typed evidence

harness/tests/test_formula.py

@@ -8,7 +8,13 @@ part of the schema-linking artifact. The store is frontmatter-YAML + SQL body.
 """
 
 
+from datetime import UTC, datetime
+
+from tht.decisions import DecisionRecord
+from tht.evidence import formula_store
 from tht.evidence.formula_store import ConceptFormula, retrieve_formula, save_formula
+from tht.evidence.session import project_session
+from tht.session.models import SchemaLinking
 
 
 def test_formula_retrieval_by_concept(tmp_path):
@@ -82,3 +88,63 @@ def test_concept_formula_default_status(tmp_path):
     f = ConceptFormula(concept="x", columns=["c"], sql="SELECT 1")
     assert f.status == "draft"  # not yet reviewed
     assert f.sources == []
+
+
+def test_reviewed_legacy_formula_becomes_curated_formula_with_stable_provenance():
+    formula = ConceptFormula(
+        concept="fascia pediatrica",
+        columns=["clinical.patient.birth_date"],
+        sql="CASE WHEN age < 18 THEN 'pediatrica' ELSE 'adulta' END",
+        status="reviewed",
+        sources=["Regola clinica approvata dal gruppo pediatrico."],
+    )
+
+    migrated = formula_store.legacy_formula_to_curated(
+        formula, legacy_path="formulas/fascia-pediatrica-1.sql.md",
+    )
+
+    assert migrated is not None
+    assert migrated.id == "evidence:fascia-pediatrica"
+    assert migrated.title == "Fascia pediatrica"
+    assert migrated.kind == "formula"
+    assert migrated.payload.concept == formula.concept
+    assert migrated.payload.columns == ("clinical.patient.birth_date",)
+    assert migrated.payload.sql == formula.sql
+    assert migrated.provenance.source_file == "source/formulas/fascia-pediatrica-1.sql.md"
+    assert migrated.provenance.supporting_excerpts == tuple(formula.sources)
+    assert migrated.review_items == ()
+    assert formula_store.legacy_formula_to_curated(
+        formula, legacy_path="formulas/fascia-pediatrica-1.sql.md",
+    ).id == migrated.id
+
+
+def test_session_formula_proposal_is_versioned_and_is_not_published_evidence(tmp_path):
+    linking = SchemaLinking(
+        question="Conta i pazienti pediatrici",
+        concept_formulas=[{
+            "concept": "fascia pediatrica",
+            "columns": ["clinical.patient.birth_date"],
+            "sql": "CASE WHEN age < 18 THEN 'pediatrica' ELSE 'adulta' END",
+            "sources": ["Sintetizzata nella sessione"],
+        }],
+    )
+    decisions = [DecisionRecord(
+        seq=9,
+        ts=datetime(2026, 8, 25, tzinfo=UTC),
+        type="concept_formula_approved",
+        subject="phase:4",
+        detail="fascia pediatrica",
+    )]
+
+    projected = project_session(decisions, linking, tmp_path / "evidence")
+
+    assert projected == [{
+        "schema_version": 1,
+        "kind": "formula_proposal",
+        "publication": "session_only",
+        "concept": "fascia pediatrica",
+        "columns": ["clinical.patient.birth_date"],
+        "sql": "CASE WHEN age < 18 THEN 'pediatrica' ELSE 'adulta' END",
+        "sources": ["Sintetizzata nella sessione"],
+        "decision_seq": 9,
+    }]