Document RC provenance at baseline selection

- Keep the compatibility invariant beside the baseline profile assignment where provenance must remain unchanged.

Validation: bazel test --nocache_test_results //comp/networkpath/npcollector/impl:impl_test

Author: AlexandreYang

comp/networkpath/npcollector/impl/baseline.go

@@ -59,6 +59,9 @@ func addBaselineCandidate(selected []baselineCandidate, candidate baselineCandid
 	return selected
 }
 
+// addBaselinePath marks the path as baseline-selected without changing its
+// admission provenance. Paths admitted by Dynamic RC retain their config ID,
+// source, and tags.
 func addBaselinePath(selected []baselineCandidate, path common.Pathtest, signals npmodel.ConnectionSignals) []baselineCandidate {
 	path.DynamicTestProfile = payload.DynamicTestProfileBaseline
 	return addBaselineCandidate(selected, baselineCandidate{

comp/networkpath/npcollector/impl/npcollector.go

@@ -323,8 +323,6 @@ func (s *npCollectorImpl) scheduleNetworkPathTests(origin payload.PathOrigin, co
 	}
 	for conn := range conns {
 		connCount++
-		// Baseline mode changes only post-filter ranking. All modes use the same
-		// local-plus-RC filter, and any winning RC attribution is preserved below.
 		evaluation := s.evaluateNetworkPathForConn(conn, origin, vpcSubnets)
 		if !evaluation.shouldSchedule {
 			s.logger.Tracef("Skipped connection: addr=%s, protocol=%s", conn.Dest, conn.Type)