From 31d71138c908f350f0ba971c400ea008e568621f Mon Sep 17 00:00:00 2001
From: sysops <sysops@LenovoT14Gen5>
Date: Thu, 6 Aug 2026 19:22:19 +0200
Subject: [PATCH] fix: MIME-Encoded-Word-Betreffs mit Windows-1252 werden nicht
 dekodiert
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

decodeMIMEHeader() nutzte mime.WordDecoder ohne CharsetReader. Go kennt
dort nativ nur UTF-8/US-ASCII/ISO-8859-1, alles andere (z.B.
Windows-1252) ließ DecodeHeader() scheitern, Betreff blieb roh
("=?Windows-1252?Q?...?="). CharsetReader ergänzt, nutzt dieselbe
htmlindex-Logik wie decodeCharset() für den Body (vgl. PROJ-57).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01WapWkrQusDuBMhaN8WyuXB
---
 pkg/mailparser/parser.go | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/pkg/mailparser/parser.go b/pkg/mailparser/parser.go
index f40e84a..49fe6a1 100644
--- a/pkg/mailparser/parser.go
+++ b/pkg/mailparser/parser.go
@@ -324,9 +324,20 @@ func decodeBody(data []byte, cte string) []byte {
 	return data
 }
 
-// decodeMIMEHeader decodes RFC 2047 encoded-word headers.
+// decodeMIMEHeader decodes RFC 2047 encoded-word headers. Go's mime package
+// only knows UTF-8/US-ASCII/ISO-8859-1 natively; CharsetReader closes that
+// gap for charsets like Windows-1252 using the same htmlindex lookup as
+// decodeCharset for the body.
 func decodeMIMEHeader(s string) string {
-	dec := new(mime.WordDecoder)
+	dec := &mime.WordDecoder{
+		CharsetReader: func(charset string, input io.Reader) (io.Reader, error) {
+			data, err := io.ReadAll(input)
+			if err != nil {
+				return nil, err
+			}
+			return bytes.NewReader(decodeCharset(data, charset)), nil
+		},
+	}
 	decoded, err := dec.DecodeHeader(s)
 	if err != nil {
 		return s