Add text-to-sql module: schema prompt through a restricted role, JSqlParser guard, read-only role with column grants and timeout, row cap, execution-based evaluation on a real PostgreSQL

Co-Authored-By: Claude Sonnet 5.5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01JXVi2GMQ7bR5EmbUFdDj7N

text-to-sql/src/main/java/com/ankurm/texttosql/QueryRunner.java

@@ -0,0 +1,56 @@
+package com.ankurm.texttosql;
+
+import java.sql.Connection;
+import java.sql.ResultSet;
+import java.sql.ResultSetMetaData;
+import java.sql.SQLException;
+import java.sql.Statement;
+import java.util.ArrayList;
+import java.util.List;
+
+/** Runs one query and returns at most {@code maxRows} rows, saying whether it stopped early. */
+public final class QueryRunner {
+
+    public record Rows(List<String> columns, List<List<String>> rows, boolean truncated) {
+    }
+
+    private QueryRunner() {
+    }
+
+    public static Rows run(Connection c, String sql, int maxRows) throws SQLException {
+        c.setAutoCommit(false);   // lets the JDBC driver ask the server for only maxRows + 1 rows
+        try (Statement st = c.createStatement()) {
+            st.setMaxRows(maxRows + 1);
+            boolean hasResult = st.execute(sql);
+            while (!hasResult && st.getUpdateCount() != -1) {
+                hasResult = st.getMoreResults();
+            }
+            if (!hasResult) {
+                return new Rows(List.of(), List.of(), false);
+            }
+            try (ResultSet rs = st.getResultSet()) {
+                ResultSetMetaData md = rs.getMetaData();
+                List<String> cols = new ArrayList<>();
+                for (int i = 1; i <= md.getColumnCount(); i++) {
+                    cols.add(md.getColumnLabel(i));
+                }
+                List<List<String>> out = new ArrayList<>();
+                boolean truncated = false;
+                while (rs.next()) {
+                    if (out.size() == maxRows) {
+                        truncated = true;
+                        break;
+                    }
+                    List<String> row = new ArrayList<>();
+                    for (int i = 1; i <= cols.size(); i++) {
+                        row.add(rs.getString(i));
+                    }
+                    out.add(row);
+                }
+                return new Rows(cols, out, truncated);
+            }
+        } finally {
+            c.rollback();
+        }
+    }
+}