feat: SMTP email notification channel with UI and ingest

Migration 006, email config DB/env, smtplib sender, settings API,
Settings UI section, and dispatch on event/problem ingest.

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/app/services/notification_settings.py

@@ -13,6 +13,7 @@ from app.models.notification_channel import NotificationChannel
 VALID_SEVERITIES = frozenset({"info", "warning", "high", "critical"})
 CHANNEL_TELEGRAM = "telegram"
 CHANNEL_WEBHOOK = "webhook"
+CHANNEL_EMAIL = "email"
 
 
 @dataclass(frozen=True)
@@ -50,6 +51,29 @@ class WebhookConfig:
         return self.enabled and self.configured
 
 
+@dataclass(frozen=True)
+class EmailConfig:
+    enabled: bool
+    smtp_host: str
+    smtp_port: int
+    smtp_user: str
+    smtp_password: str
+    mail_from: str
+    mail_to: str
+    smtp_starttls: bool
+    smtp_ssl: bool
+    min_severity: str
+    source: str  # env | db
+
+    @property
+    def configured(self) -> bool:
+        return bool(self.smtp_host.strip() and self.mail_from.strip() and self.mail_to.strip())
+
+    @property
+    def active(self) -> bool:
+        return self.enabled and self.configured
+
+
 def _telegram_from_env() -> TelegramConfig:
     settings = get_settings()
     return TelegramConfig(
@@ -211,3 +235,121 @@ def upsert_webhook_channel(
     db.commit()
     db.refresh(row)
     return get_effective_webhook_config(db)
+
+
+def _email_from_env() -> EmailConfig:
+    settings = get_settings()
+    return EmailConfig(
+        enabled=bool(settings.smtp_enabled),
+        smtp_host=settings.smtp_host.strip(),
+        smtp_port=int(settings.smtp_port or 587),
+        smtp_user=settings.smtp_user.strip(),
+        smtp_password=settings.smtp_password,
+        mail_from=settings.smtp_from.strip(),
+        mail_to=settings.smtp_to.strip(),
+        smtp_starttls=bool(settings.smtp_starttls),
+        smtp_ssl=bool(settings.smtp_ssl),
+        min_severity=settings.smtp_min_severity.strip() or "high",
+        source="env",
+    )
+
+
+def get_effective_email_config(db: Session | None = None) -> EmailConfig:
+    if db is None:
+        from app.database import SessionLocal
+
+        session = SessionLocal()
+        try:
+            return get_effective_email_config(session)
+        finally:
+            session.close()
+
+    row = db.scalar(select(NotificationChannel).where(NotificationChannel.channel == CHANNEL_EMAIL))
+    env_cfg = _email_from_env()
+    if row is None:
+        return env_cfg
+
+    host = (row.smtp_host or "").strip() or env_cfg.smtp_host
+    port = row.smtp_port if row.smtp_port is not None else env_cfg.smtp_port
+    user = (row.smtp_user or "").strip() or env_cfg.smtp_user
+    password = (row.smtp_password or "") or env_cfg.smtp_password
+    mail_from = (row.mail_from or "").strip() or env_cfg.mail_from
+    mail_to = (row.mail_to or "").strip() or env_cfg.mail_to
+    min_sev = (row.min_severity or "").strip() or env_cfg.min_severity
+    if min_sev not in VALID_SEVERITIES:
+        min_sev = env_cfg.min_severity
+
+    return EmailConfig(
+        enabled=bool(row.enabled),
+        smtp_host=host,
+        smtp_port=int(port or 587),
+        smtp_user=user,
+        smtp_password=password,
+        mail_from=mail_from,
+        mail_to=mail_to,
+        smtp_starttls=bool(row.smtp_starttls),
+        smtp_ssl=bool(row.smtp_ssl),
+        min_severity=min_sev,
+        source="db",
+    )
+
+
+def upsert_email_channel(
+    db: Session,
+    *,
+    enabled: bool | None = None,
+    smtp_host: str | None = None,
+    smtp_port: int | None = None,
+    smtp_user: str | None = None,
+    smtp_password: str | None = None,
+    mail_from: str | None = None,
+    mail_to: str | None = None,
+    smtp_starttls: bool | None = None,
+    smtp_ssl: bool | None = None,
+    min_severity: str | None = None,
+) -> EmailConfig:
+    row = db.scalar(select(NotificationChannel).where(NotificationChannel.channel == CHANNEL_EMAIL))
+    env_cfg = _email_from_env()
+
+    if row is None:
+        row = NotificationChannel(
+            channel=CHANNEL_EMAIL,
+            enabled=env_cfg.enabled,
+            min_severity=env_cfg.min_severity,
+            smtp_host=env_cfg.smtp_host or None,
+            smtp_port=env_cfg.smtp_port,
+            smtp_user=env_cfg.smtp_user or None,
+            smtp_password=env_cfg.smtp_password or None,
+            mail_from=env_cfg.mail_from or None,
+            mail_to=env_cfg.mail_to or None,
+            smtp_starttls=env_cfg.smtp_starttls,
+            smtp_ssl=env_cfg.smtp_ssl,
+        )
+        db.add(row)
+
+    if enabled is not None:
+        row.enabled = enabled
+    if min_severity is not None:
+        if min_severity not in VALID_SEVERITIES:
+            raise ValueError(f"invalid min_severity: {min_severity}")
+        row.min_severity = min_severity
+    if smtp_host is not None and smtp_host.strip():
+        row.smtp_host = smtp_host.strip()
+    if smtp_port is not None:
+        row.smtp_port = smtp_port
+    if smtp_user is not None:
+        row.smtp_user = smtp_user.strip() or None
+    if smtp_password is not None and smtp_password.strip():
+        row.smtp_password = smtp_password
+    if mail_from is not None and mail_from.strip():
+        row.mail_from = mail_from.strip()
+    if mail_to is not None and mail_to.strip():
+        row.mail_to = mail_to.strip()
+    if smtp_starttls is not None:
+        row.smtp_starttls = smtp_starttls
+    if smtp_ssl is not None:
+        row.smtp_ssl = smtp_ssl
+
+    db.commit()
+    db.refresh(row)
+    return get_effective_email_config(db)