fix(library): expose scan activity and failed analysis file details

services/api/internal/library/scanner_test.go

@@ -55,7 +55,7 @@ func TestWalkAndHash(t *testing.T) {
 	write("_incoming/new.mp3", 10)
 	write("big.mp3", 3<<20)
 
-	found, err := walk(root, func(rel string) bool { return rel == "_incoming/new.mp3" })
+	found, err := walk(root, func(rel string) bool { return rel == "_incoming/new.mp3" }, nil)
 	require.NoError(t, err)
 	assert.ElementsMatch(t, []string{"Artist/Album/01 - Song.FLAC", "big.mp3"}, rels(found))
 	for _, w := range found {
@@ -69,10 +69,42 @@ func TestWalkAndHash(t *testing.T) {
 	require.NoError(t, err)
 	assert.Equal(t, h1, h2, "hash survives a rename")
 
-	_, err = walk(filepath.Join(root, "nope"), func(string) bool { return false })
+	_, err = walk(filepath.Join(root, "nope"), func(string) bool { return false }, nil)
 	assert.Error(t, err)
 }
 
+func TestWalkReportsIncrementalProgress(t *testing.T) {
+	root := t.TempDir()
+	for _, dir := range []string{"a-empty", "b-album", ".hidden"} {
+		require.NoError(t, os.MkdirAll(filepath.Join(root, dir), 0o755))
+	}
+	for _, rel := range []string{"b-album/1.mp3", "b-album/2.flac", "b-album/skip.mp3", ".hidden/3.mp3"} {
+		require.NoError(t, os.WriteFile(filepath.Join(root, filepath.FromSlash(rel)), []byte("audio"), 0o644))
+	}
+	var counts, folders []int
+	var paths []string
+	found, err := walk(root, func(rel string) bool { return rel == "b-album/skip.mp3" }, func(n, dirs int, path string) {
+		counts, folders, paths = append(counts, n), append(folders, dirs), append(paths, path)
+	})
+	require.NoError(t, err)
+	require.Len(t, found, 2)
+	assert.Equal(t, []int{0, 0, 0, 1, 2}, counts, "reports activity before any file is found and after each accepted audio file")
+	assert.Equal(t, []int{1, 2, 3, 3, 3}, folders)
+	assert.Equal(t, []string{".", "a-empty", "b-album", "b-album", "b-album"}, paths)
+}
+
+func TestProgressDTOIncludesWalkActivity(t *testing.T) {
+	p := Progress{Phase: "walking", Running: true, Found: 7, WalkedDirs: 4, CurrentDir: "Artist/Album"}
+	dto := progressDTO(p)
+	require.NotNil(t, dto.Phase)
+	assert.Equal(t, "walking", string(*dto.Phase))
+	assert.Equal(t, p.Found, dto.Found)
+	require.NotNil(t, dto.WalkedDirs)
+	assert.Equal(t, p.WalkedDirs, *dto.WalkedDirs)
+	require.NotNil(t, dto.CurrentDir)
+	assert.Equal(t, p.CurrentDir, *dto.CurrentDir)
+}
+
 func TestParseFFprobe(t *testing.T) {
 	raw := []byte(`{
 	  "streams": [