diff --git a/internal/tender/documents_scraped_filter.go b/internal/tender/documents_scraped_filter.go
index 8265fbc..899c0cc 100644
--- a/internal/tender/documents_scraped_filter.go
+++ b/internal/tender/documents_scraped_filter.go
@@ -12,7 +12,8 @@ import (
 
 const (
 	// contractFoldersWithDocsCacheTTL avoids scanning MinIO on every documents_scraped list request.
-	contractFoldersWithDocsCacheTTL = 60 * time.Second
+	// Kept >= resolve timeout so a slow scan is not immediately invalidated for waiters.
+	contractFoldersWithDocsCacheTTL = 15 * time.Minute
 	// contractFoldersWithDocsResolveTimeout bounds a single MinIO procedure scan.
 	contractFoldersWithDocsResolveTimeout = 3 * time.Minute
 )
@@ -65,7 +66,9 @@ func (s *tenderService) cachedContractFolderIDsWithDocuments(ctx context.Context
 		}
 		s.contractFoldersCacheMu.Unlock()
 
-		resolveCtx, cancel := context.WithTimeout(ctx, contractFoldersWithDocsResolveTimeout)
+		// Detach from the caller's cancellation so a client disconnect or proxy timeout
+		// does not abort the shared singleflight scan for every waiter.
+		resolveCtx, cancel := context.WithTimeout(context.WithoutCancel(ctx), contractFoldersWithDocsResolveTimeout)
 		defer cancel()
 
 		procedures, listErr := s.listProceduresWithDocuments(resolveCtx)
diff --git a/internal/tender/documents_scraped_filter_test.go b/internal/tender/documents_scraped_filter_test.go
index 33e8eaa..f208593 100644
--- a/internal/tender/documents_scraped_filter_test.go
+++ b/internal/tender/documents_scraped_filter_test.go
@@ -29,7 +29,9 @@ func (m *mockProcedureDocumentLister) ListProceduresWithDocuments(context.Contex
 }
 
 type stubProcedureDocumentStorage struct {
-	lister *mockProcedureDocumentLister
+	lister interface {
+		ListProceduresWithDocuments(ctx context.Context) ([]ai_summarizer.ProcedureDocumentsSummary, error)
+	}
 }
 
 func (s stubProcedureDocumentStorage) GetSummaryFromStorage(context.Context, string, string) (string, error) {
@@ -156,6 +158,64 @@ func TestContractFolderIDsFromProceduresDedupesAndSkipsEmpty(t *testing.T) {
 	}
 }
 
+type scanStartedProcedureLister struct {
+	mockProcedureDocumentLister
+	started chan struct{}
+}
+
+func (m *scanStartedProcedureLister) ListProceduresWithDocuments(ctx context.Context) ([]ai_summarizer.ProcedureDocumentsSummary, error) {
+	if m.started != nil {
+		select {
+		case <-m.started:
+		default:
+			close(m.started)
+		}
+	}
+	time.Sleep(50 * time.Millisecond)
+	if err := ctx.Err(); err != nil {
+		return nil, err
+	}
+	return m.mockProcedureDocumentLister.ListProceduresWithDocuments(ctx)
+}
+
+func TestCachedContractFolderIDsSurvivesCallerCancellation(t *testing.T) {
+	started := make(chan struct{})
+	lister := &scanStartedProcedureLister{
+		mockProcedureDocumentLister: mockProcedureDocumentLister{
+			procedures: []ai_summarizer.ProcedureDocumentsSummary{
+				{ContractFolderID: "folder-1", DocumentCount: 1},
+			},
+		},
+		started: started,
+	}
+	svc := &tenderService{aiSummarizerStorage: stubProcedureDocumentStorage{lister: lister}}
+
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	errCh := make(chan error, 1)
+	var ids []string
+	go func() {
+		var err error
+		ids, err = svc.cachedContractFolderIDsWithDocuments(ctx)
+		errCh <- err
+	}()
+
+	select {
+	case <-started:
+	case <-time.After(2 * time.Second):
+		t.Fatal("MinIO scan did not start")
+	}
+	cancel()
+
+	if err := <-errCh; err != nil {
+		t.Fatalf("expected shared scan to finish despite caller cancel: %v", err)
+	}
+	if len(ids) != 1 || ids[0] != "folder-1" {
+		t.Fatalf("unexpected folder ids: %#v", ids)
+	}
+}
+
 func TestContractFoldersWithDocsCacheExpires(t *testing.T) {
 	lister := &mockProcedureDocumentLister{
 		procedures: []ai_summarizer.ProcedureDocumentsSummary{