refactor composer to use sqlalchemy, avoid string concatenations and follow conventions

api/recon/build.py

@@ -137,6 +137,11 @@ def merge_into_recon(dataset: str, extracted: dict[str, Any]) -> Recon:
 
     relationships = [Relationship.parse(r) for r in (aug.get("relationships", []) or [])]
 
+    # Storage-encoding overrides (optional). Keyed by Column.semantic_type; each
+    # value maps a role (e.g. "as_date") to a SQL template with a `{col}`
+    # placeholder. The composer merges these over its built-in defaults.
+    encodings: dict[str, dict[str, str]] = aug.get("encodings", {}) or {}
+
     column_to_tables: dict[str, list[str]] = {}
     for t in tables.values():
         for c in t.columns:
@@ -150,6 +155,7 @@ def merge_into_recon(dataset: str, extracted: dict[str, Any]) -> Recon:
         metrics=metrics,
         column_to_tables=column_to_tables,
         relationships=relationships,
+        encodings=encodings,
     )