Found a few ways in which the Braille problem with browsers could resurface. Fixed now.

internal/atspi/document_caret_test.go

@@ -13,3 +13,58 @@ func TestDocumentCaretCharacterPreservesDelimiters(t *testing.T) {
 		}
 	}
 }
+
+func TestIncompleteEmbeddedTextRecoversOnlyWholeObject(t *testing.T) {
+	for _, test := range []struct {
+		name, label, expanded, want string
+		start, end, count           int
+		incomplete                  bool
+	}{
+		{"failed child", "Before Linked title after", "Before  after", "Before Linked title after", 0, 14, 14, true},
+		{"complete expansion", "Different author label", "Before Linked title after", "Before Linked title after", 0, 14, 14, false},
+		{"wrapped first line", "Whole object label", "Before  after", "Before  after", 0, 14, 28, true},
+		{"wrapped last line", "Whole object label", "Before  after", "Before  after", 14, 28, 28, true},
+		{"unknown count", "Whole object label", "Before  after", "Before  after", 0, 14, 0, true},
+		{"invalid name", "Before \ufffc after", "Before  after", "Before  after", 0, 14, 14, true},
+		{"empty name", " ", "Before  after", "Before  after", 0, 14, 14, true},
+	} {
+		t.Run(test.name, func(t *testing.T) {
+			line := DocumentCaretText{Text: "Before \ufffc after", Start: test.start, End: test.end, CharacterCount: test.count,
+				SelectionStart: 8, SelectionEnd: 10, TextAttributeRuns: []TextAttributeRun{{Start: 8, End: 10}}}
+			line.applyExpandedText(test.expanded, test.label, test.incomplete)
+			if line.Text != test.want || line.RawText != "Before \ufffc after" || !line.Expanded ||
+				line.Start != test.start || line.End != test.end || line.CharacterCount != test.count ||
+				line.SelectionStart != 8 || line.SelectionEnd != 10 || line.TextAttributeRuns[0].Start != 8 {
+				t.Fatalf("expanded line = %+v", line)
+			}
+		})
+	}
+}
+
+func TestCaretLineRepairPreservesOnlyMatchingExpansion(t *testing.T) {
+	snapshot := Snapshot{Text: "Before Linked title after", BrailleLine: "Before \ufffc after", BrailleLineStart: 10, CharacterCount: 24, TextCaretKnown: true}
+	line := DocumentCaretText{Text: "Before \ufffc after", RawText: "Before \ufffc after", Start: 10, End: 24, CharacterCount: 24}
+	snapshot.applyDocumentCaretLine(line, 18)
+	if snapshot.Text != "Before Linked title after" || snapshot.BrailleLine != line.RawText || snapshot.BrailleCaret != 18 || snapshot.CharacterCount != 24 {
+		t.Fatalf("matching expansion lost: %+v", snapshot)
+	}
+	// A newly available count permits whole-object recovery after the
+	// initial snapshot could not establish whether its line was complete.
+	snapshot.CharacterCount = 0
+	line.Text = "Before Recovered title after"
+	snapshot.applyDocumentCaretLine(line, 18)
+	if snapshot.Text != "Before Recovered title after" {
+		t.Fatalf("newly recovered expansion ignored: %+v", snapshot)
+	}
+	// Equal raw strings on different lines must not reuse the old expansion.
+	line.Start, line.End, line.Text = 0, 14, "Before New title after"
+	snapshot.applyDocumentCaretLine(line, 0)
+	if snapshot.Text != "Before New title after" || snapshot.BrailleLineStart != 0 || snapshot.BrailleCaret != 0 {
+		t.Fatalf("new line inherited stale expansion: %+v", snapshot)
+	}
+	line.Text, line.RawText = "New  plain 猫", "New  plain 猫"
+	snapshot.applyDocumentCaretLine(line, 2)
+	if snapshot.Text != "New plain 猫" || snapshot.BrailleLine != "New  plain 猫" || snapshot.BrailleCaret != 2 {
+		t.Fatalf("plain line repair lost text or spacing: %+v", snapshot)
+	}
+}