mail: robustes Decoding gegen unbekannte Charsets (x-unknown); OAuth-Token 30 Tage

- _safe_decode() faengt LookupError bei unbekannten/kaputten Mail-Charsets
  (z.B. 'x-unknown') ab, Fallback utf-8 -> latin-1. Verhindert Crash der
  Mail-Suche/Read bei einzelnen kaputt-kodierten Mails.
- common.py: OAuth access_token Lifetime 24h -> 30 Tage (weniger Re-Auth in claude.ai)
- .gitignore: *.before-* Backups ausschliessen

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

.gitignore

@@ -4,3 +4,4 @@ __pycache__/
 tokens.json
 config.json
 .active_tokens.json
+*.before-*

common.py

@@ -193,7 +193,7 @@ async def oauth_token(request: Request):
         return JSONResponse({"error": "unsupported_grant_type"}, status_code=400)
 
     access_token = secrets.token_urlsafe(48)
-    expires_in = 86400
+    expires_in = 2592000  # 30 days
     tokens = _load_access_tokens()
     # Cleanup expired
     now = time.time()

mail/server.py

@@ -46,6 +46,21 @@ mcp = FastMCP("Mail", stateless_http=True,
               transport_security={"enable_dns_rebinding_protection": False})
 
 
+def _safe_decode(payload, charset):
+    """Decode bytes robust gegen unbekannte/kaputte Charsets (z.B. 'x-unknown')."""
+    if not isinstance(payload, bytes):
+        return str(payload)
+    for cs in (charset, "utf-8", "latin-1"):
+        if not cs:
+            continue
+        try:
+            return payload.decode(cs, errors="replace")
+        except (LookupError, TypeError):
+            continue
+    # Letzter Fallback: latin-1 akzeptiert jedes Byte
+    return payload.decode("latin-1", errors="replace")
+
+
 def _decode_hdr(raw):
     if not raw:
         return ""
@@ -53,7 +68,7 @@ def _decode_hdr(raw):
     decoded = []
     for data, charset in parts:
         if isinstance(data, bytes):
-            decoded.append(data.decode(charset or "utf-8", errors="replace"))
+            decoded.append(_safe_decode(data, charset))
         else:
             decoded.append(str(data))
     return " ".join(decoded)
@@ -65,16 +80,16 @@ def _get_body(msg):
             if part.get_content_type() == "text/plain":
                 payload = part.get_payload(decode=True)
                 if payload:
-                    return payload.decode(part.get_content_charset() or "utf-8", errors="replace")
+                    return _safe_decode(payload, part.get_content_charset())
         for part in msg.walk():
             if part.get_content_type() == "text/html":
                 payload = part.get_payload(decode=True)
                 if payload:
-                    return "[HTML] " + payload.decode(part.get_content_charset() or "utf-8", errors="replace")
+                    return "[HTML] " + _safe_decode(payload, part.get_content_charset())
     else:
         payload = msg.get_payload(decode=True)
         if payload:
-            return payload.decode(msg.get_content_charset() or "utf-8", errors="replace")
+            return _safe_decode(payload, msg.get_content_charset())
     return ""