From a101f6699ccfe8bf40de8bd2ceb58423f5414652 Mon Sep 17 00:00:00 2001
From: Paul Buetow <paul@buetow.org>
Date: Thu, 7 May 2026 00:37:28 +0300
Subject: Fix scan cancellation progress error for q0

---
 internal/service/scan.go      |  6 ++++-
 internal/service/scan_test.go | 55 ++++++++++++++++++++++++++++++++++++-------
 2 files changed, 52 insertions(+), 9 deletions(-)

diff --git a/internal/service/scan.go b/internal/service/scan.go
index 52bc5c5..2a56f93 100644
--- a/internal/service/scan.go
+++ b/internal/service/scan.go
@@ -58,7 +58,11 @@ func (s *scanService) TriggerRescan(ctx context.Context) error {
 
 	go func() {
 		defer cancel()
-		if err := s.scanner.Scan(scanCtx, s.mediaRoot, progress); err != nil {
+		err := s.scanner.Scan(scanCtx, s.mediaRoot, progress)
+		if err == nil {
+			err = scanCtx.Err()
+		}
+		if err != nil {
 			progress.Done(err)
 			s.logger.Error("rescan failed", "err", err)
 		} else {
diff --git a/internal/service/scan_test.go b/internal/service/scan_test.go
index aba647f..fcd7e0a 100644
--- a/internal/service/scan_test.go
+++ b/internal/service/scan_test.go
@@ -14,17 +14,17 @@ func TestScanService_ScanLibrary(t *testing.T) {
 	ctx := context.Background()
 
 	tests := []struct {
-		name     string
-		scanErr  error
-		wantErr  bool
+		name    string
+		scanErr error
+		wantErr bool
 	}{
 		{
 			name: "ok",
 		},
 		{
-			name:     "scan error",
-			scanErr:  errors.New("boom"),
-			wantErr:  false, // TriggerRescan returns nil immediately; background goroutine logs error
+			name:    "scan error",
+			scanErr: errors.New("boom"),
+			wantErr: false, // TriggerRescan returns nil immediately; background goroutine logs error
 		},
 	}
 
@@ -62,18 +62,18 @@ func TestScanService_CancelledByAppContext(t *testing.T) {
 	appCtx, appCancel := context.WithCancel(context.Background())
 	defer appCancel()
 
-	done := make(chan struct{})
+	done := make(chan struct{}, 1)
 	started := make(chan struct{})
 	sc := &fakeScanner{
 		scanFunc: func(scanCtx context.Context, _ string, progress *model.ScanProgress) error {
 			close(started)
 			<-scanCtx.Done()
-			close(done)
 			return scanCtx.Err()
 		},
 	}
 
 	svc := NewScanService(appCtx, sc, "/media", clock.RealClock{}, nil)
+	svc.doneCh = done
 	if err := svc.TriggerRescan(context.Background()); err != nil {
 		t.Fatalf("unexpected error: %v", err)
 	}
@@ -95,3 +95,42 @@ func TestScanService_CancelledByAppContext(t *testing.T) {
 		t.Fatal("expected a last error after cancellation")
 	}
 }
+
+func TestScanService_CancelledContextRecordedWhenScannerReturnsNil(t *testing.T) {
+	appCtx, appCancel := context.WithCancel(context.Background())
+	defer appCancel()
+
+	done := make(chan struct{}, 1)
+	started := make(chan struct{})
+	sc := &fakeScanner{
+		scanFunc: func(scanCtx context.Context, _ string, progress *model.ScanProgress) error {
+			progress.Start(1)
+			close(started)
+			<-scanCtx.Done()
+			return nil
+		},
+	}
+
+	svc := NewScanService(appCtx, sc, "/media", clock.RealClock{}, nil)
+	svc.doneCh = done
+	if err := svc.TriggerRescan(context.Background()); err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	<-started
+	appCancel()
+
+	select {
+	case <-done:
+	case <-time.After(5 * time.Second):
+		t.Fatal("timeout waiting for scan goroutine to exit after app context cancellation")
+	}
+
+	p := svc.ScanProgress(context.Background())
+	if p.Running {
+		t.Fatal("expected scan to be stopped after app context cancellation")
+	}
+	if p.LastError != context.Canceled.Error() {
+		t.Fatalf("expected last error %q, got %q", context.Canceled.Error(), p.LastError)
+	}
+}
-- 
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