docs: the history phrases the id sweep missed, restated as present-tense facts or traps (#6277)

A wider pass for "previous", "before the fix", "we shipped" and the
like. The chi double-subtree, uppercase Vorbis key and stopPropagation
comments now describe the trap they guard; commit hashes, CI run
numbers and a deleted file name are gone; uuidString's comment says
what it returns.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/library/genre_test.go

@@ -334,7 +334,7 @@ func TestExtractGenres_EndToEnd(t *testing.T) {
 	if err != nil {
 		t.Fatalf("tag.ReadFrom: %v", err)
 	}
-	// Confirm the upstream behaviour this fix exists for is still present —
+	// Confirm the upstream behaviour this reader works around is still present —
 	// if dhowden ever fixes it, this test tells us the workaround can go.
 	if welded := meta.Genre(); welded != "Alternative RockRock" {
 		t.Logf("note: dhowden/tag no longer welds multi-values (got %q)", welded)

internal/library/mbids_test.go

@@ -97,10 +97,9 @@ func TestExtractMBIDs_MissingTagsReturnEmpty(t *testing.T) {
 }
 
 func TestExtractMBIDs_VorbisUppercaseKeysMiss(t *testing.T) {
-	// Regression guard: real dhowden never produces uppercase Vorbis
-	// keys. If a future change starts looking up "MUSICBRAINZ_ALBUMID"
-	// directly, this test must keep returning empty so we don't
-	// silently re-introduce the v0 bug where every album skipped.
+	// Real dhowden never produces uppercase Vorbis keys. Looking up
+	// "MUSICBRAINZ_ALBUMID" directly would find nothing, and every album
+	// would be skipped; this test keeps that lookup returning empty.
 	m := stubMeta{
 		format: tag.VORBIS,
 		raw: map[string]interface{}{

internal/library/song_link_test.go

@@ -168,8 +168,8 @@ func TestCrossReleaseLinkNeedsAutoResolve_Integration(t *testing.T) {
 
 // A merge keeps the removed copy's link to the song on another release,
 // whichever copy's id names the song. That copy has no song_id of its own,
-// and before the fix its link was lost whenever the random ids made it the
-// key (the flaky failure in run 8891).
+// and its link must survive whichever way the random ids fall, including when
+// they make it the key.
 func TestMergeInheritsSongLink_Integration(t *testing.T) {
 	for _, removeAlbumCut := range []bool{true, false} {
 		pool := newPool(t)

internal/library/vorbisgenre_test.go

@@ -170,7 +170,7 @@ func TestExtractGenres_FLACRepeatedFields(t *testing.T) {
 	if err != nil {
 		t.Fatalf("tag.ReadFrom: %v", err)
 	}
-	// Confirm the upstream behaviour this fix exists for is still present.
+	// Confirm the upstream behaviour this reader works around is still present.
 	if got := meta.Genre(); got != "Instrumental Hip Hop" {
 		t.Logf("note: dhowden/tag no longer keeps only the last GENRE (got %q)", got)
 	}