perf: batch gateway submits and isolate callbacks

gateway/cmd/gateway/main.go

@@ -32,7 +32,8 @@ func main() {
 		cmppAddr = ":17890"
 	}
 	apiBaseURL := os.Getenv("API_BASE_URL")
-	upstreamManager := &upstream.Manager{APIBaseURL: apiBaseURL}
+	callbackBaseURL := getenv("GATEWAY_CALLBACK_API_BASE_URL", apiBaseURL)
+	upstreamManager := &upstream.Manager{APIBaseURL: apiBaseURL, EventAPIBaseURL: callbackBaseURL}
 	var worker *submitworker.Worker
 	var resultOutbox *resultoutbox.Outbox
 	channelLimiter, err := ratelimit.New(os.Getenv("REDIS_URL"))
@@ -75,12 +76,12 @@ func main() {
 			worker.Group = getenv("GATEWAY_SUBMIT_GROUP", "cmpp-gateway")
 			worker.Consumer = getenv("GATEWAY_SUBMIT_CONSUMER", "gateway-1")
 			worker.Concurrency = positiveEnvInt("GATEWAY_SUBMIT_WORKER_CONCURRENCY", 64)
-			worker.APIBaseURL = apiBaseURL
+			worker.APIBaseURL = callbackBaseURL
 			resultOutbox = resultoutbox.New(worker.Redis)
 			resultOutbox.Stream = getenv("GATEWAY_SUBMIT_RESULT_STREAM", "gateway.submit.results")
 			resultOutbox.Group = getenv("GATEWAY_SUBMIT_RESULT_GROUP", "cmpp-api-callback")
 			resultOutbox.Consumer = getenv("GATEWAY_SUBMIT_RESULT_CONSUMER", "gateway-1")
-			resultOutbox.APIBaseURL = apiBaseURL
+			resultOutbox.APIBaseURL = callbackBaseURL
 			resultOutbox.Concurrency = positiveEnvInt("GATEWAY_SUBMIT_RESULT_WORKER_CONCURRENCY", 8)
 			worker.ResultOutbox = resultOutbox
 			upstreamManager.SubmitSegmentPublisher = resultOutbox
@@ -161,7 +162,7 @@ func main() {
 		return snapshot
 	}))
 	control.Register(mux, control.Server{
-		APIBaseURL: apiBaseURL,
+		APIBaseURL: callbackBaseURL,
 		Upstream:   upstreamManager,
 		Limiter:    channelLimiter,
 		Submit: func(ctx context.Context, command queue.SubmitCommand) (queue.SubmitResult, error) {