Add retained run report helpers

tests/test_core.py

@@ -16,7 +16,12 @@ from guide_board.planning import (
     validate_assessment_profile,
     validate_target_profile,
 )
-from guide_board.retention import build_trend_summary, list_retained_runs
+from guide_board.retention import (
+    build_trend_summary,
+    list_retained_runs,
+    retained_run_report_paths,
+    select_retained_run,
+)
 from guide_board.schema import assert_valid
 from guide_board.service import ServiceHandle, start_service
 
@@ -288,6 +293,19 @@ class CoreArchitectureTests(unittest.TestCase):
             self.assertEqual(gate["status"], "passed")
             self.assertEqual(gate["passed_groups"], 1)
 
+            latest = select_retained_run(
+                runs_dir,
+                target_profile_ref="sample-repository",
+                assessment_profile_ref="sample-noop-assessment",
+            )
+            self.assertIsNotNone(latest)
+            assert latest is not None
+            self.assertEqual(latest["run_id"], "run-new")
+            self.assertEqual(
+                retained_run_report_paths(latest)["report"],
+                str(runs_dir / "run-new" / "reports" / "report.md"),
+            )
+
             missing_gate = evaluate_trend_gates(
                 trend,
                 target_profile_ref="missing-target",