The fetcher's "saved opportunities" and "fetched opportunities" lines now name the source

internal/fetcher/fetcher.go

@@ -246,6 +246,9 @@ func (f *Fetcher) startFrom(
 // Opportunities that match the skip rules (see WithSkipRules) are marked
 // Skipped first. The store keeps the marks of an opportunity it already
 // has, so only new ones are skipped.
+//
+// Each save is one worker's, so its lines are logged with the first
+// opportunity's Source.
 func (f *Fetcher) save(
 	ctx context.Context,
 	logger *slog.Logger,
@@ -255,6 +258,10 @@ func (f *Fetcher) save(
 		return nil
 	}
 
+	if len(opportunities) > 0 {
+		logger = logger.With("source", opportunities[0].Source)
+	}
+
 	filters := f.markSkipped(opportunities)
 
 	result, err := f.store.SaveOpportunities(ctx, opportunities)