Fix agent output summary for pipeline steps (#812)

* Changes from fix/agent-output-summary-for-pipeline-steps

* feat: Optimize pipeline summary extraction and fix regex vulnerability

* fix: Use fallback summary for pipeline steps when extraction fails

* fix: Strip follow-up session scaffold from pipeline step fallback summaries

apps/ui/src/lib/summary-selection.ts

@@ -0,0 +1,14 @@
+export type SummaryValue = string | null | undefined;
+
+/**
+ * Returns the first summary candidate that contains non-whitespace content.
+ * The original string is returned (without trimming) to preserve formatting.
+ */
+export function getFirstNonEmptySummary(...candidates: SummaryValue[]): string | null {
+  for (const candidate of candidates) {
+    if (typeof candidate === 'string' && candidate.trim().length > 0) {
+      return candidate;
+    }
+  }
+  return null;
+}