Inherit email link addresses from hosting and proxy settings

backend/app/routers/newsletters.py

@@ -6,6 +6,7 @@ from uuid import UUID
 from fastapi import APIRouter, Depends, HTTPException, Query, Response
 from pydantic import Field, field_validator
 
+from ..services.public_urls import magent_public_url
 from ..auth import get_current_user, require_admin
 from ..runtime import get_runtime_settings
 from ..services import newsletters as service, newsletter_store as store, newsletter_catalog as catalog
@@ -19,7 +20,7 @@ class Settings(StrictPayload):
     weekday: int = Field(ge=0, le=6)
     hour: int = Field(ge=0, le=23)
     limit_titles: int = Field(ge=1, le=24)
-    public_url: str = Field(max_length=500)
+    public_url: str = Field(default="", max_length=500)
     intro: str = Field(default='', max_length=2000)
     revision: int = Field(ge=1)
     _url = field_validator('public_url')(RecapSettings.origin_only.__func__)
@@ -114,10 +115,11 @@ def overview(offset: int = Query(default=0, ge=0, le=1_000_000), user: dict = De
 @router.put('/admin/newsletters')
 def settings(payload: Settings, user: dict = Depends(require_admin)):
     try:
-        ready, detail = service.delivery_ready(payload.public_url)
+        public_url = magent_public_url(payload.public_url or store.settings()['public_url'])
+        ready, detail = service.delivery_ready(public_url)
         if payload.enabled and not ready:
             raise service.NewsletterError(detail)
-        return store.save_settings(payload.model_dump(), datetime.now(timezone.utc))
+        return store.save_settings({**payload.model_dump(), "public_url": public_url}, datetime.now(timezone.utc))
     except (service.NewsletterError, store.Conflict) as exc:
         fail(exc)