refactor(i-g): BUG-018 Pilot — mail/services.py Split Schritt 1 (crypto+sanitize+pgp extrahiert)

Die 3 pure-function Bloecke aus services.py in eigene Sub-Module extrahiert: crypto.py (AES-256 Fernet mit Legacy-Salt + MAIL_ENCRYPTION_KEY-Guard), sanitize.py (nh3 HTML-Sanitizer), pgp.py (pgpy-basiert). Rueckwaertskompatibilitaet via Re-Export-Imports in services.py — alle 4 Consumer unveraendert.

Beweis: mail+sig_label_routes 51/51 passed in 105.52s; ruff clean.

app/plugins/builtins/mail/services.py

@@ -2,7 +2,6 @@
 
 from __future__ import annotations
 
-import base64
 import json
 import logging
 import os
@@ -16,16 +15,26 @@ from email.utils import formataddr, formatdate, make_msgid
 import aiofiles
 import aioimaplib
 import aiosmtplib
-import nh3
-import pgpy
-from cryptography.fernet import Fernet
-from cryptography.hazmat.primitives import hashes
-from cryptography.hazmat.primitives.kdf.pbkdf2 import PBKDF2HMAC
 from sqlalchemy import and_, func, or_, select
 from sqlalchemy.ext.asyncio import AsyncSession
 
 from app.config import settings
 from app.core.notifications import create_notification
+
+# ── Re-exports from extracted sub-modules (BUG-018 pilot split) ──
+# Backwards compatibility: all consumers still import from
+# ``app.plugins.builtins.mail.services`` unchanged.
+from app.plugins.builtins.mail.crypto import (  # noqa: E402
+    decrypt_password,
+    encrypt_password,
+    generate_salt,
+)
+from app.plugins.builtins.mail.pgp import (  # noqa: E402,F401
+    import_pgp_private_key,
+    import_pgp_public_key,
+    pgp_decrypt_message,
+    pgp_encrypt_message,
+)
 from app.plugins.builtins.mail.models import (
     Mail,
     MailAccount,
@@ -38,6 +47,7 @@ from app.plugins.builtins.mail.models import (
     MailTemplate,
     VacationSentLog,
 )
+from app.plugins.builtins.mail.sanitize import sanitize_html  # noqa: E402,F401
 
 logger = logging.getLogger(__name__)
 
@@ -129,118 +139,6 @@ def attachment_to_response(att: MailAttachment) -> dict:
     }
 
 
-# ─── AES-256 Encryption (Fernet) ───
-
-MAIL_ENCRYPTION_KEY = os.environ.get("MAIL_ENCRYPTION_KEY")
-if not MAIL_ENCRYPTION_KEY:
-    raise RuntimeError("MAIL_ENCRYPTION_KEY environment variable is required. Set it to a strong random value.")
-
-# Legacy salt for backward compatibility with existing encrypted passwords
-_LEGACY_SALT = b"leocrm-mail-salt"
-
-
-def _derive_key(password: str, salt: bytes) -> bytes:
-    """Derive a 32-byte Fernet key from a password using PBKDF2 with the given salt."""
-    kdf = PBKDF2HMAC(
-        algorithm=hashes.SHA256(),
-        length=32,
-        salt=salt,
-        iterations=480000,
-    )
-    return base64.urlsafe_b64encode(kdf.derive(password.encode()))
-
-
-def generate_salt() -> str:
-    """Generate a random 32-byte salt and return as base64 string."""
-    salt = os.urandom(32)
-    return base64.urlsafe_b64encode(salt).decode()
-
-
-def _get_fernet(salt_b64: str | None = None) -> Fernet:
-    """Get a Fernet instance. If salt_b64 is provided, use it; otherwise use legacy salt."""
-    if salt_b64:
-        salt = base64.urlsafe_b64decode(salt_b64.encode())
-    else:
-        salt = _LEGACY_SALT
-    return Fernet(_derive_key(MAIL_ENCRYPTION_KEY, salt))
-
-
-def encrypt_password(plaintext: str, salt_b64: str | None = None) -> str:
-    """Encrypt a password using AES-256 (Fernet). Returns base64 ciphertext.
-
-    If salt_b64 is provided, uses that salt for key derivation.
-    If not, uses the legacy hardcoded salt (for backward compatibility).
-    """
-    fernet = _get_fernet(salt_b64)
-    return fernet.encrypt(plaintext.encode()).decode()
-
-
-def decrypt_password(ciphertext: str, salt_b64: str | None = None) -> str:
-    """Decrypt a password encrypted with encrypt_password.
-
-    If salt_b64 is provided, uses that salt for key derivation.
-    If not, uses the legacy hardcoded salt (for backward compatibility).
-    """
-    fernet = _get_fernet(salt_b64)
-    return fernet.decrypt(ciphertext.encode()).decode()
-
-
-# ─── HTML Sanitization (F-MAIL: no script tags) ───
-
-
-def sanitize_html(raw_html: str) -> str:
-    """Sanitize HTML using nh3 — removes script tags and dangerous attributes."""
-    if not raw_html:
-        return ""
-    return nh3.clean(
-        raw_html,
-        tags={
-            "a",
-            "b",
-            "br",
-            "div",
-            "em",
-            "h1",
-            "h2",
-            "h3",
-            "h4",
-            "h5",
-            "h6",
-            "hr",
-            "i",
-            "img",
-            "li",
-            "ol",
-            "p",
-            "span",
-            "strong",
-            "table",
-            "tbody",
-            "td",
-            "th",
-            "thead",
-            "tr",
-            "u",
-            "ul",
-            "blockquote",
-            "code",
-            "pre",
-            "font",
-            "center",
-        },
-        attributes={
-            "a": {"href", "title", "target"},
-            "img": {"src", "alt", "width", "height"},
-            "span": {"style"},
-            "div": {"style"},
-            "font": {"color", "size", "face"},
-            "p": {"style"},
-            "td": {"style"},
-            "th": {"style"},
-        },
-    )
-
-
 # ─── IMAP Quota Parser ───
 
 
@@ -1966,48 +1864,6 @@ async def log_vacation_sent(
     await db.flush()
 
 
-# ─── PGP Service (F-MAIL-12) ───
-
-
-def import_pgp_private_key(private_key_armored: str, passphrase: str = "") -> tuple[str, str]:
-    """Import a PGP private key. Returns (key_id, public_key_armored)."""
-    key, _ = pgpy.PGPKey.from_blob(private_key_armored)
-    if key.is_protected:
-        with key.unlock(passphrase):
-            pub_key = key.pubkey
-            key_id = str(key.fingerprint).upper()[-16:]
-            return key_id, str(pub_key)
-    pub_key = key.pubkey
-    key_id = str(key.fingerprint).upper()[-16:]
-    return key_id, str(pub_key)
-
-
-def import_pgp_public_key(public_key_armored: str) -> str:
-    """Import a PGP public key. Returns key_id."""
-    key, _ = pgpy.PGPKey.from_blob(public_key_armored)
-    return str(key.fingerprint).upper()[-16:]
-
-
-def pgp_encrypt_message(plaintext: str, recipient_public_key_armored: str) -> str:
-    """Encrypt a message with recipient's public PGP key."""
-    pub_key, _ = pgpy.PGPKey.from_blob(recipient_public_key_armored)
-    msg = pgpy.PGPMessage.new(plaintext)
-    encrypted = pub_key.encrypt(msg)
-    return str(encrypted)
-
-
-def pgp_decrypt_message(ciphertext: str, private_key_armored: str, passphrase: str = "") -> str:
-    """Decrypt a PGP-encrypted message."""
-    key, _ = pgpy.PGPKey.from_blob(private_key_armored)
-    enc_msg = pgpy.PGPMessage.from_blob(ciphertext)
-    if key.is_protected:
-        with key.unlock(passphrase):
-            decrypted = key.decrypt(enc_msg)
-            return decrypted.message.decode("utf-8")
-    decrypted = key.decrypt(enc_msg)
-    return decrypted.message.decode("utf-8")
-
-
 # ─── Contact Linking (F-MAIL-10) ───