feat: Refactor integration settings loading to use environment variable fallbacks for Calibre OPDS

abogen/web/routes/books.py

@@ -7,7 +7,7 @@ from flask.typing import ResponseReturnValue
 
 from abogen.web.routes.utils.settings import (
     load_settings,
-    stored_integration_config,
+    load_integration_settings,
 )
 from abogen.web.routes.utils.voice import template_options
 from abogen.web.routes.utils.form import build_pending_job_from_extraction
@@ -37,7 +37,7 @@ def _build_calibre_client(payload: Dict[str, Any]) -> CalibreOPDSClient:
 @books_bp.get("/")
 def find_books_page() -> ResponseReturnValue:
     settings = load_settings()
-    integrations = settings.get("integrations", {})
+    integrations = load_integration_settings()
     return render_template(
         "find_books.html",
         integrations=integrations,
@@ -54,8 +54,7 @@ def search_books() -> ResponseReturnValue:
 
 @books_bp.get("/calibre/feed")
 def calibre_opds_feed() -> ResponseReturnValue:
-    settings = load_settings()
-    integrations = settings.get("integrations", {})
+    integrations = load_integration_settings()
     calibre_settings = integrations.get("calibre_opds", {})
     
     payload = {

abogen/web/routes/utils/settings.py

@@ -343,6 +343,25 @@ def load_integration_settings() -> Dict[str, Dict[str, Any]]:
             # Do not clear the token here
             # merged["api_token"] = ""
         integrations[key] = merged
+
+    # Environment variable fallbacks for Calibre OPDS
+    calibre = integrations["calibre_opds"]
+    if not calibre.get("base_url"):
+        calibre["base_url"] = os.environ.get("CALIBRE_SERVER_HOST", "")
+    if not calibre.get("username"):
+        calibre["username"] = os.environ.get("OPDS_USERNAME", "")
+    if not calibre.get("password"):
+        calibre["password"] = os.environ.get("OPDS_PASSWORD", "")
+    
+    # If we have a password (from storage or env), mark it as present for the UI
+    if calibre.get("password"):
+        calibre["has_password"] = True
+
+    # Auto-enable if configured via env but not explicitly disabled in config
+    stored_calibre = stored_integrations.get("calibre_opds")
+    if stored_calibre is None and calibre.get("base_url"):
+        calibre["enabled"] = True
+
     return integrations