diff --git a/docs/help/testing.md b/docs/help/testing.md
index e5977cd705d..e3ddc2564f9 100644
--- a/docs/help/testing.md
+++ b/docs/help/testing.md
@@ -579,6 +579,7 @@ Notes:
   - `OPENCLAW_LIVE_ACP_BIND_AGENT=gemini`
   - `OPENCLAW_LIVE_ACP_BIND_AGENTS=claude,codex,gemini`
   - `OPENCLAW_LIVE_ACP_BIND_AGENT_COMMAND='npx -y @agentclientprotocol/claude-agent-acp@<version>'`
+  - `OPENCLAW_LIVE_ACP_BIND_CODEX_MODEL=gpt-5.4`
 - Notes:
   - This lane uses the gateway `chat.send` surface with admin-only synthetic originating-route fields so tests can attach message-channel context without pretending to deliver externally.
   - When `OPENCLAW_LIVE_ACP_BIND_AGENT_COMMAND` is unset, the test uses the embedded `acpx` plugin's built-in agent registry for the selected ACP harness agent.
diff --git a/src/gateway/gateway-acp-bind.live.test.ts b/src/gateway/gateway-acp-bind.live.test.ts
index 77a13bc9c8c..3ed7c7c1aac 100644
--- a/src/gateway/gateway-acp-bind.live.test.ts
+++ b/src/gateway/gateway-acp-bind.live.test.ts
@@ -36,6 +36,7 @@ const describeLive = LIVE && ACP_BIND_LIVE ? describe : describe.skip;
 
 const CONNECT_TIMEOUT_MS = 90_000;
 const LIVE_TIMEOUT_MS = 240_000;
+const DEFAULT_LIVE_CODEX_MODEL = "gpt-5.4";
 type LiveAcpAgent = "claude" | "codex" | "gemini";
 
 function createSlackCurrentConversationBindingRegistry() {
@@ -129,6 +130,32 @@ function logLiveStep(message: string): void {
   console.info(`[live-acp-bind] ${message}`);
 }
 
+async function prepareCodexHomeForLiveBindTest(): Promise<void> {
+  const home = process.env.HOME?.trim();
+  if (!home) {
+    return;
+  }
+  const model = process.env.OPENCLAW_LIVE_ACP_BIND_CODEX_MODEL?.trim() || DEFAULT_LIVE_CODEX_MODEL;
+  const codexHome = path.join(home, ".codex");
+  await fs.mkdir(codexHome, { recursive: true });
+  const configPath = path.join(codexHome, "config.toml");
+  let rawConfig = "";
+  try {
+    rawConfig = await fs.readFile(configPath, "utf8");
+  } catch (error) {
+    if ((error as NodeJS.ErrnoException)?.code !== "ENOENT") {
+      throw error;
+    }
+  }
+  const modelLine = `model = ${JSON.stringify(model)}`;
+  const nextConfig = /^model\s*=.*$/m.test(rawConfig)
+    ? rawConfig.replace(/^model\s*=.*$/m, modelLine)
+    : `${modelLine}\n${rawConfig}`;
+  await fs.writeFile(configPath, nextConfig, "utf8");
+  process.env.CODEX_HOME = codexHome;
+  logLiveStep(`using Codex ACP model ${model}`);
+}
+
 async function waitForGatewayPort(params: {
   host: string;
   port: number;
@@ -414,6 +441,7 @@ describeLive("gateway live (ACP bind)", () => {
         skipGmail: process.env.OPENCLAW_SKIP_GMAIL_WATCHER,
         skipCron: process.env.OPENCLAW_SKIP_CRON,
         skipCanvas: process.env.OPENCLAW_SKIP_CANVAS_HOST,
+        codexHome: process.env.CODEX_HOME,
       };
       const liveAgent = normalizeAcpAgent(process.env.OPENCLAW_LIVE_ACP_BIND_AGENT);
       const agentCommandOverride =
@@ -438,6 +466,9 @@ describeLive("gateway live (ACP bind)", () => {
       process.env.OPENCLAW_SKIP_CANVAS_HOST = "1";
       process.env.OPENCLAW_GATEWAY_TOKEN = token;
       process.env.OPENCLAW_GATEWAY_PORT = String(port);
+      if (liveAgent === "codex" && !agentCommandOverride) {
+        await prepareCodexHomeForLiveBindTest();
+      }
 
       const cfg = loadConfig();
       const acpxEntry = cfg.plugins?.entries?.acpx;
@@ -866,6 +897,11 @@ describeLive("gateway live (ACP bind)", () => {
         } else {
           process.env.OPENCLAW_SKIP_CANVAS_HOST = previous.skipCanvas;
         }
+        if (previous.codexHome === undefined) {
+          delete process.env.CODEX_HOME;
+        } else {
+          process.env.CODEX_HOME = previous.codexHome;
+        }
       }
     },
     LIVE_TIMEOUT_MS + 360_000,