harden ffmpeg pipeline failure handling and stream mapping

internal/app/app_test.go

@@ -2,9 +2,11 @@ package app
 
 import (
 	"context"
+	"fmt"
 	"net/http"
 	"net/http/httptest"
 	"os"
+	"os/exec"
 	"path/filepath"
 	"strings"
 	"testing"
@@ -20,6 +22,12 @@ type noopTagger struct{}
 
 func (n noopTagger) TagFLAC(string, tag.Metadata, string) error { return nil }
 
+type failingTagger struct {
+	err error
+}
+
+func (f failingTagger) TagFLAC(string, tag.Metadata, string) error { return f.err }
+
 type fakeProvider struct {
 	url string
 }
@@ -237,6 +245,56 @@ func TestTrackRipPipeline(t *testing.T) {
 	}
 }
 
+func TestTrackRipFailsWhenTaggerReportsMissingFFmpeg(t *testing.T) {
+	tmp := t.TempDir()
+
+	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
+		_, _ = w.Write([]byte("audio-bytes"))
+	}))
+	defer ts.Close()
+
+	d := config.DefaultConfigData()
+	d.Downloads.Folder = tmp
+	d.Downloads.SourceSubdirectories = false
+	cfg := &config.Config{File: d, Session: d}
+
+	sqlite, err := store.NewSQLite(filepath.Join(tmp, "db.sqlite"))
+	if err != nil {
+		t.Fatalf("NewSQLite() error = %v", err)
+	}
+	defer func() { _ = sqlite.Close() }()
+
+	m := &Main{
+		Config: cfg,
+		Providers: map[string]provider.Client{
+			"qobuz": &fakeProvider{url: ts.URL},
+		},
+		Store:  sqlite,
+		DL:     download.NewWithOptions(true, false),
+		Tagger: failingTagger{err: fmt.Errorf("ffmpeg not found: %w", exec.ErrNotFound)},
+	}
+
+	ctx := context.Background()
+	if err = m.AddByID(ctx, "qobuz", "track", "19512574"); err != nil {
+		t.Fatalf("AddByID() error = %v", err)
+	}
+	if err = m.Resolve(ctx); err != nil {
+		t.Fatalf("Resolve() error = %v", err)
+	}
+	err = m.Rip(ctx)
+	if err == nil {
+		t.Fatalf("expected rip failure")
+	}
+
+	ok, err := sqlite.IsDownloaded(ctx, "qobuz", "19512574")
+	if err != nil {
+		t.Fatalf("IsDownloaded() error = %v", err)
+	}
+	if ok {
+		t.Fatalf("expected track not marked downloaded")
+	}
+}
+
 func TestAlbumRipPipeline(t *testing.T) {
 	tmp := t.TempDir()