verbose live UI + tool-level SSE events + Groq default + regression tests

api/prompts/text_to_sql.user.txt

@@ -0,0 +1,10 @@
+Question:
+{question}
+
+Schema (only the tables that look relevant; you may use any of these):
+{schema_block}
+
+Metric catalog (copy the SQL verbatim when the question maps to one):
+{metrics_block}
+
+Return only the SQL in a ```sql fenced block.{retry_hint}