diff --git a/AGENTS.md b/AGENTS.md
index 1b7b7b6..ca385a1 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -4,7 +4,7 @@ Rules for anyone, human or automated, changing this repository.
 
 ## Build and test
 
-- Go 1.27.2 or newer (see `go.mod`).
+- Go 1.27.3 or newer (see `go.mod`).
 - `make check` runs `gofmt` verification, `go vet`, `go test ./...` and
   `go test -race ./...`. CI also runs `staticcheck` and `govulncheck`.
 - Tests are hermetic: they use an in-memory Redis and synthetic GeoIP data and
diff --git a/Dockerfile b/Dockerfile
index 26e6c8e..76e58b4 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,7 +1,7 @@
 # Base images are pinned by multi-arch index digest; keep the tag for
 # readability and bump tag and digest together
 # (`docker buildx imagetools inspect <image:tag>`).
-FROM golang:1.27.2-alpine@sha256:f92b6ef800e499660581efdabdf25d9d817a9d124eaf900924f0504e7e27e12d AS build
+FROM golang:1.27.3-alpine@sha256:d200d2dd76b03a99b52651fd1325aff7dcd35422c35c01bac56571b0507f3deb AS build
 
 # Optional module-proxy override for restricted networks:
 #   docker build --build-arg GOPROXY=https://goproxy.cn,direct .
diff --git a/go.mod b/go.mod
index af8cfad..735def7 100644
--- a/go.mod
+++ b/go.mod
@@ -1,6 +1,6 @@
 module github.com/Crawlora-org/FreeProxyAPI
 
-go 1.27.2
+go 1.27.3
 
 require (
 	github.com/alicebob/miniredis/v2 v2.40.0
diff --git a/internal/probe/tester_test.go b/internal/probe/tester_test.go
index 9461039..017dd46 100644
--- a/internal/probe/tester_test.go
+++ b/internal/probe/tester_test.go
@@ -117,6 +117,9 @@ func TestRunProbeEchoThroughHTTPProxy(t *testing.T) {
 	requests := 0
 	var seenNonce string
 	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		// The transport writes request bytes asynchronously. Keep the response
+		// behind that write so the traffic counter has a deterministic snapshot.
+		time.Sleep(10 * time.Millisecond)
 		requests++
 		seenNonce = r.URL.Query().Get(EchoNonceParam)
 		w.Header().Set("Content-Type", "application/json")