Disable buffering on SSE endpoints

src/main/kotlin/com/android/trisolarisserver/controller/RazorpayQrPayments.kt

@@ -15,6 +15,7 @@ import com.android.trisolarisserver.repo.RazorpaySettingsRepo
 import com.android.trisolarisserver.repo.RazorpayWebhookLogRepo
 import com.android.trisolarisserver.security.MyPrincipal
 import com.fasterxml.jackson.databind.ObjectMapper
+import jakarta.servlet.http.HttpServletResponse
 import org.springframework.http.HttpEntity
 import org.springframework.http.HttpHeaders
 import org.springframework.http.HttpMethod
@@ -267,12 +268,20 @@ class RazorpayQrPayments(
         @PathVariable propertyId: UUID,
         @PathVariable bookingId: UUID,
         @PathVariable qrId: String,
-        @AuthenticationPrincipal principal: MyPrincipal?
+        @AuthenticationPrincipal principal: MyPrincipal?,
+        response: HttpServletResponse
     ): SseEmitter {
         requireRole(propertyAccess, propertyId, principal, Role.ADMIN, Role.MANAGER, Role.STAFF)
+        prepareSse(response)
         return qrEvents.subscribe(propertyId, qrId)
     }
 
+    private fun prepareSse(response: HttpServletResponse) {
+        response.setHeader("Cache-Control", "no-cache")
+        response.setHeader("Connection", "keep-alive")
+        response.setHeader("X-Accel-Buffering", "no")
+    }
+
     @GetMapping("/qr")
     fun listQr(
         @PathVariable propertyId: UUID,