fix: use distinct agents for each server

FlipcashCore/Sources/FlipcashCore/Clients/Payments API/Utilities/Interceptors/UserAgentInterceptor.swift

@@ -11,18 +11,34 @@ import GRPC
 import NIO
 import NIOHPACK
 
+/// Attaches a `User-Agent` header to every outgoing gRPC request.
+///
+/// The product name is derived from the RPC method path so that each
+/// backend receives the user agent it expects:
+///   - OCP server  (`/ocp.*`)       → `OpenCodeProtocol/iOS/{version}`
+///   - Flipcash server              → `Flipcash/iOS/{version}`
 class UserAgentInterceptor<Request, Response>: ClientInterceptor<Request, Response>, @unchecked Sendable {
     override func send(_ part: GRPCClientRequestPart<Request>, promise: EventLoopPromise<Void>?, context: ClientInterceptorContext<Request, Response>) {
         var modifiedPart = part
         switch modifiedPart {
         case .metadata(var headers):
-            headers.add(.userAgent, value: "Flipcash/iOS/\(AppMeta.version)")
+            let product = Self.productName(for: context.path)
+            headers.add(.userAgent, value: "\(product)/iOS/\(AppMeta.version)")
             modifiedPart = .metadata(headers)
         default:
             break
         }
         context.send(modifiedPart, promise: promise)
     }
+
+    /// Returns the product name for the `User-Agent` header based on
+    /// the gRPC method path (e.g. `/ocp.transaction.v1.Transaction/SubmitIntent`).
+    private static func productName(for path: String) -> String {
+        if path.hasPrefix("/ocp.") {
+            return "OpenCodeProtocol"
+        }
+        return "Flipcash"
+    }
 }
 
 // MARK: - App -