2 files changed, 41 insertions, 1 deletions

diff --git a/src/signatures.cpp b/src/signatures.cpp
index eb43048..ef631d6 100644
--- a/src/signatures.cpp
+++ b/src/signatures.cpp
@@ -69,6 +69,20 @@ bool isQuoted(const QString &line)
     return line.startsWith(QLatin1Char('>'));
 }
 
+/// \p text with trailing blank lines removed, the same normalisation the block
+/// scan below applies. text() returns file content verbatim, so a signature
+/// file ends with the newline every editor writes; without this the match
+/// compares a block with no trailing newline against a known entry that has
+/// one, and the guard silently fails, appending a second signature instead of
+/// replacing the first.
+QString stripTrailingBlankLines(const QString &text)
+{
+    QStringList lines = text.split(QLatin1Char('\n'));
+    while (!lines.isEmpty() && lines.last().trimmed().isEmpty())
+        lines.removeLast();
+    return lines.join(QLatin1Char('\n'));
+}
+
 /// The index of the first line of the quote, or -1 when the buffer has none.
 ///
 /// The attribution line ("On Mon, someone wrote:") is deliberately NOT
@@ -164,9 +178,18 @@ QStringList withoutSignature(const QStringList &lines, int delimiter)
 QString replace(const QString &buffer, const QString &signature,
                 const QStringList &known, Position position)
 {
+    // Normalise known to the same footing the block scan uses, once here rather
+    // than per comparison. knownSignatures() passes text() verbatim, trailing
+    // newline and all, and the match must be newline-insensitive or the guard
+    // treats every on-disk signature as unknown.
+    QStringList normalized;
+    normalized.reserve(known.size());
+    for (const QString &entry : known)
+        normalized.append(stripTrailingBlankLines(entry));
+
     QStringList lines = buffer.split(QLatin1Char('\n'));
 
-    const int existing = existingSignature(lines, known);
+    const int existing = existingSignature(lines, normalized);
     if (existing >= 0)
         lines = withoutSignature(lines, existing);
 
diff --git a/tests/test_signatures.cpp b/tests/test_signatures.cpp
index 31f9eb4..47b404b 100644
--- a/tests/test_signatures.cpp
+++ b/tests/test_signatures.cpp
@@ -40,6 +40,7 @@ private slots:
     void selectingNoneRemovesAKnownSignature();
     void aBlockMatchingNoKnownSignatureIsNotRemoved();
     void aDelimiterInsideTheQuoteIsNotTheSignature();
+    void aSignatureReadBackFromDiskIsReplaced();
 
 private:
     /// Writes \p files as name -> content into a fresh temporary directory.
@@ -273,5 +274,21 @@ void TestSignatures::aDelimiterInsideTheQuoteIsNotTheSignature()
     QVERIFY(result.endsWith(QStringLiteral("-- \nJane Doe")));
 }
 
+void TestSignatures::aSignatureReadBackFromDiskIsReplaced()
+{
+    // known here is what knownSignatures() produces: text() verbatim, carrying
+    // the trailing newline every editor writes into a file. The block scan
+    // treats a trailing blank line as separation rather than text, so a naive
+    // match compares "Jane Doe" against "Jane Doe\n" and silently fails, and
+    // switching then APPENDS a second signature instead of replacing the first.
+    const QStringList known = { QStringLiteral("Jane Doe\n") };
+    const QString buffer = QStringLiteral("Hello.\n\n-- \nJane Doe\n");
+
+    const QString result = Signatures::replace(
+        buffer, QStringLiteral("Brief"), known, Signatures::Position::End);
+
+    QCOMPARE(result, QStringLiteral("Hello.\n\n-- \nBrief"));
+}
+
 QTEST_MAIN(TestSignatures)
 #include "test_signatures.moc"