diff --git a/changelog/unreleased/codex-cloak-0.166.md b/changelog/unreleased/codex-cloak-0.166.md
new file mode 100644
index 00000000..bb70f619
--- /dev/null
+++ b/changelog/unreleased/codex-cloak-0.166.md
@@ -0,0 +1,7 @@
+### English
+
+- Bump Codex outbound cloaking User-Agent to official stable `0.166.0` (`rust-v0.166.0`). CPA pin stays at 0.154.
+
+### 中文
+
+- Codex 出站伪装 User-Agent 升至官方稳定版 `0.166.0`（`rust-v0.166.0`）。CPA pin 仍为 0.154。
diff --git a/internal/providers/codex/credential.go b/internal/providers/codex/credential.go
index dba74794..99f30744 100644
--- a/internal/providers/codex/credential.go
+++ b/internal/providers/codex/credential.go
@@ -53,7 +53,7 @@ const (
 	pathWhamUsage = "/wham/usage"
 
 	// Cloaking: upstream gates on the official codex CLI UA/originator.
-	UserAgent  = "codex-tui/0.165.0 (Mac OS 26.5.2; arm64) iTerm.app/3.6.11 (codex-tui; 0.165.0)"
+	UserAgent  = "codex-tui/0.166.0 (Mac OS 26.5.2; arm64) iTerm.app/3.6.11 (codex-tui; 0.166.0)"
 	Originator = "codex-tui"
 
 	QuotaUnit = "rate_limit_window"
diff --git a/internal/providers/codex/headers_passthrough_test.go b/internal/providers/codex/headers_passthrough_test.go
index ce64f9bb..cd32ead2 100644
--- a/internal/providers/codex/headers_passthrough_test.go
+++ b/internal/providers/codex/headers_passthrough_test.go
@@ -58,7 +58,7 @@ func TestWithCodexClientHeadersFilters(t *testing.T) {
 }
 
 func TestUserAgentPinnedToOfficialStable(t *testing.T) {
-	if !strings.Contains(UserAgent, "0.165.0") {
-		t.Fatalf("UserAgent=%q want 0.165.0", UserAgent)
+	if !strings.Contains(UserAgent, "0.166.0") {
+		t.Fatalf("UserAgent=%q want 0.166.0", UserAgent)
 	}
 }