diff --git a/.gitignore b/.gitignore
index 59ba284..c02e5f2 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,5 +1,5 @@
 .DS_Store
-naviwatcher
+/naviwatcher
 naviwatcher-linux
 naviwatcher-mac
 naviwatcher.exe
diff --git a/cmd/naviwatcher/datastore_smoke_test.go b/cmd/naviwatcher/datastore_smoke_test.go
new file mode 100644
index 0000000..765d555
--- /dev/null
+++ b/cmd/naviwatcher/datastore_smoke_test.go
@@ -0,0 +1,159 @@
+package main
+
+import (
+	"context"
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"testing"
+
+	"naviwatcher/internal/config"
+	"naviwatcher/internal/database"
+	"naviwatcher/internal/notifier"
+	"naviwatcher/internal/scanner"
+	"naviwatcher/internal/web"
+)
+
+// TestDataFlowSmoke seeds an in-memory DB with a monitored artist, one local
+// album, and a missing external release, then exercises the full
+// scan -> notify -> web pipeline end to end:
+//   - ScanAll reports the missing release
+//   - NotifyOnce (with a stub sender) sends exactly the missing release and
+//     marks it as sent, so a second run reports nothing
+//   - The Web UI dashboard requires auth and renders the artist + missing count,
+//     and the artist detail page renders the missing release
+//
+// This is the acceptance smoke check for Task 9.
+func TestDataFlowSmoke(t *testing.T) {
+	db, err := database.New(":memory:")
+	if err != nil {
+		t.Fatalf("open :memory: db: %v", err)
+	}
+	defer db.Close()
+
+	ctx := context.Background()
+
+	// Seed: one monitored artist with one local album ...
+	if err := database.SaveArtistSettings(db, &database.ArtistSettings{
+		ID:        "ar1",
+		Name:      "Pink Floyd",
+		MBID:      "abcdef",
+		Monitored: true,
+	}); err != nil {
+		t.Fatalf("seed artist: %v", err)
+	}
+	if err := database.SaveLocalAlbum(db, &database.LocalAlbum{
+		ID:       "al1",
+		ArtistID: "ar1",
+		Title:    "The Wall",
+	}); err != nil {
+		t.Fatalf("seed local album: %v", err)
+	}
+	// ... and a missing external release (not present locally).
+	if err := database.SaveExternalRelease(db, &database.ExternalRelease{
+		RGID:        "rg-missing",
+		ArtistID:    "ar1",
+		Title:       "Animals",
+		Type:        "Album",
+		ReleaseDate: "1977-01-01",
+	}); err != nil {
+		t.Fatalf("seed external release: %v", err)
+	}
+
+	// 1) ScanAll should surface exactly the missing release.
+	missing, err := scanner.ScanAll(ctx, db, 0.85)
+	if err != nil {
+		t.Fatalf("ScanAll: %v", err)
+	}
+	if len(missing) != 1 {
+		t.Fatalf("expected 1 missing release, got %d", len(missing))
+	}
+	if missing[0].RGID != "rg-missing" || missing[0].Title != "Animals" {
+		t.Fatalf("unexpected missing release: %+v", missing[0])
+	}
+
+	// 2) Notifier: stub sender, first run notifies 1, second run notifies 0.
+	var sent []string
+	stub := stubSender{onSend: func(msg string) error {
+		sent = append(sent, msg)
+		return nil
+	}}
+	tgCfg := config.TelegramConfig{Enabled: true}
+
+	n1, err := notifier.NotifyOnce(ctx, db, stub, tgCfg, "http://localhost:8080")
+	if err != nil {
+		t.Fatalf("NotifyOnce #1: %v", err)
+	}
+	if n1 != 1 {
+		t.Fatalf("expected NotifyOnce to send 1, got %d", n1)
+	}
+	if len(sent) != 1 || !strings.Contains(sent[0], "Animals") {
+		t.Fatalf("digest missing expected content: %v", sent)
+	}
+
+	n2, err := notifier.NotifyOnce(ctx, db, stub, tgCfg, "http://localhost:8080")
+	if err != nil {
+		t.Fatalf("NotifyOnce #2: %v", err)
+	}
+	if n2 != 0 {
+		t.Fatalf("expected second NotifyOnce to send 0 (already sent), got %d", n2)
+	}
+
+	// 3) Web UI: dashboard requires basic auth and renders the artist.
+	srvCfg := &config.ServerConfig{
+		Host:     "localhost",
+		Port:     0,
+		Username: "admin",
+		Password: "secret",
+	}
+	srv := web.NewServer(srvCfg, db, "http://localhost:8080")
+
+	// Unauthenticated -> 401.
+	rec := httptest.NewRecorder()
+	req := httptest.NewRequest(http.MethodGet, "/", nil)
+	srv.Handler().ServeHTTP(rec, req)
+	if rec.Code != http.StatusUnauthorized {
+		t.Fatalf("expected 401 for unauthenticated dashboard, got %d", rec.Code)
+	}
+
+	// Authenticated -> 200 with the artist name and missing count.
+	rec = httptest.NewRecorder()
+	req = httptest.NewRequest(http.MethodGet, "/", nil)
+	req.SetBasicAuth("admin", "secret")
+	srv.Handler().ServeHTTP(rec, req)
+	if rec.Code != http.StatusOK {
+		t.Fatalf("expected 200 for authenticated dashboard, got %d", rec.Code)
+	}
+	body := rec.Body.String()
+	if !strings.Contains(body, "Pink Floyd") {
+		t.Fatalf("dashboard did not render artist name; body head:\n%s", body[:min(400, len(body))])
+	}
+
+	// Artist detail page renders the missing release.
+	rec = httptest.NewRecorder()
+	req = httptest.NewRequest(http.MethodGet, "/artist/ar1", nil)
+	req.SetBasicAuth("admin", "secret")
+	srv.Handler().ServeHTTP(rec, req)
+	if rec.Code != http.StatusOK {
+		t.Fatalf("expected 200 for artist page, got %d", rec.Code)
+	}
+	if !strings.Contains(rec.Body.String(), "Animals") {
+		t.Fatalf("artist page did not render missing release 'Animals'")
+	}
+}
+
+func min(a, b int) int {
+	if a < b {
+		return a
+	}
+	return b
+}
+
+// stubSender is a test double for notifier.Sender.
+type stubSender struct {
+	onSend func(message string) error
+}
+
+func (s stubSender) Send(_ context.Context, message string) error {
+	return s.onSend(message)
+}
diff --git a/config.yaml.example b/config.yaml.example
index d1942c0..2c70eee 100644
--- a/config.yaml.example
+++ b/config.yaml.example
@@ -22,3 +22,10 @@ telegram:
 
 scanner:
   fuzzy_threshold: 0.85
+
+# Periodic sync+scan pipeline: how often NaviWatcher pulls artists/albums from
+# Navidrome, resolves MusicBrainz discographies, and re-runs the scanner.
+# Accepts any duration Go's time.ParseDuration understands (e.g. "6h", "30m").
+# Defaults to 6h when omitted.
+sync:
+  interval: 6h
diff --git a/docs/plans/2026-07-19-notifier-webui-sync.md b/docs/plans/2026-07-19-notifier-webui-sync.md
index c71bf42..536147d 100644
--- a/docs/plans/2026-07-19-notifier-webui-sync.md
+++ b/docs/plans/2026-07-19-notifier-webui-sync.md
@@ -132,10 +132,10 @@ name collisions.)
 - [x] run tests - must pass before task 9
 
 ### Task 9: Verify acceptance criteria
-- [ ] run full suite `go test ./...` — all pass
-- [ ] run `go vet ./...` and `go build -o naviwatcher` — clean
-- [ ] verify scan→notify→web data flow with a seeded `:memory:`/file DB smoke check
-- [ ] verify config.yaml.example documents new `sync_interval` field
+- [x] run full suite `go test ./...` — all pass
+- [x] run `go vet ./...` and `go build -o naviwatcher` — clean
+- [x] verify scan→notify→web data flow with a seeded `:memory:`/file DB smoke check
+- [x] verify config.yaml.example documents new `sync_interval` field
 
 ### Task 10: Update documentation
 - [ ] add a short "How it works now" note to README/CLAUDE.md if present