Move retry-after constant to config.py (#543 review)

Author: abhishek-8081

app/core/config.py

@@ -44,3 +44,8 @@
     for origin in os.getenv("FRONTEND_ORIGINS", _DEFAULT_ORIGINS).split(",")
     if origin.strip()
 ]
+
+# --- Error handling -------------------------------------------------------
+# Advisory Retry-After sent to clients on 503 responses. This is a client
+# hint, not a measured backpressure value — the app has no queue-depth signal.
+RETRY_AFTER_SECONDS = 30

app/core/errors/handlers.py

@@ -2,12 +2,9 @@
 from fastapi.exceptions import RequestValidationError
 from fastapi.responses import JSONResponse
 
+from app.core.config import RETRY_AFTER_SECONDS
 from app.core.errors.base import AppError
 
-# Advisory retry hint on 503 responses — not a measured queue depth or backpressure
-# value; just a safe default so clients know when to try again.
-_RETRY_AFTER_SECONDS = 30
-
 
 def register_exception_handlers(app):
     @app.exception_handler(AppError)
@@ -16,7 +13,7 @@ async def app_error_handler(request: Request, exc: AppError):
         if exc.detail is not None:
             body["detail"] = exc.detail
         if exc.status_code == 503:
-            body["retry_after_seconds"] = _RETRY_AFTER_SECONDS
+            body["retry_after_seconds"] = RETRY_AFTER_SECONDS
         return JSONResponse(status_code=exc.status_code, content=body)
 
     @app.exception_handler(RequestValidationError)