diff --git a/CHANGELOG.md b/CHANGELOG.md
index 9a6cf6ebbf3..63a4fbbd160 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,7 @@ Docs: https://docs.openclaw.ai
 ### Changes
 
 - Highlight: External Secrets Management introduces a full `openclaw secrets` workflow (`audit`, `configure`, `apply`, `reload`) with runtime snapshot activation, strict `secrets apply` target-path validation, safer migration scrubbing, ref-only auth-profile support, and dedicated docs. (#26155) Thanks @joshavant.
+- Codex/WebSocket transport: make `openai-codex` WebSocket-first by default (`transport: "auto"` with SSE fallback), keep explicit per-model/runtime transport overrides, and add regression coverage + docs for transport selection.
 - Agents/Routing CLI: add `openclaw agents bindings`, `openclaw agents bind`, and `openclaw agents unbind` for account-scoped route management, including channel-only to account-scoped binding upgrades, role-aware binding identity handling, plugin-resolved binding account IDs, and optional account-binding prompts in `openclaw channels add`. (#27195) thanks @gumadeiras.
 - ACP/Thread-bound agents: make ACP agents first-class runtimes for thread sessions with `acp` spawn/send dispatch integration, acpx backend bridging, lifecycle controls, startup reconciliation, runtime cleanup, and coalesced thread replies. (#23580) thanks @osolmaz.
 - Onboarding/Plugins: let channel plugins own interactive onboarding flows with optional `configureInteractive` and `configureWhenConfigured` hooks while preserving the generic fallback path. (#27191) thanks @gumadeiras.
diff --git a/docs/concepts/model-providers.md b/docs/concepts/model-providers.md
index 6210f592482..94675b639a0 100644
--- a/docs/concepts/model-providers.md
+++ b/docs/concepts/model-providers.md
@@ -70,6 +70,8 @@ OpenClaw ships with the pi‑ai catalog. These providers require **no**
 - Auth: OAuth (ChatGPT)
 - Example model: `openai-codex/gpt-5.3-codex`
 - CLI: `openclaw onboard --auth-choice openai-codex` or `openclaw models auth login --provider openai-codex`
+- Default transport is `auto` (WebSocket-first, SSE fallback)
+- Override per model via `agents.defaults.models["openai-codex/<model>"].params.transport` (`"sse"`, `"websocket"`, or `"auto"`)
 
 ```json5
 {
diff --git a/docs/providers/openai.md b/docs/providers/openai.md
index 54e3d29e454..1a47081a9a6 100644
--- a/docs/providers/openai.md
+++ b/docs/providers/openai.md
@@ -56,6 +56,33 @@ openclaw models auth login --provider openai-codex
 }
 ```
 
+### Codex transport default
+
+OpenClaw uses `pi-ai` for model streaming. For `openai-codex/*` models you can set
+`agents.defaults.models.<provider/model>.params.transport` to select transport:
+
+- Default is `"auto"` (WebSocket-first, then SSE fallback).
+- `"sse"`: force SSE
+- `"websocket"`: force WebSocket
+- `"auto"`: try WebSocket, then fall back to SSE
+
+```json5
+{
+  agents: {
+    defaults: {
+      model: { primary: "openai-codex/gpt-5.3-codex" },
+      models: {
+        "openai-codex/gpt-5.3-codex": {
+          params: {
+            transport: "auto",
+          },
+        },
+      },
+    },
+  },
+}
+```
+
 ## Notes
 
 - Model refs always use `provider/model` (see [/concepts/models](/concepts/models)).
diff --git a/src/agents/pi-embedded-runner-extraparams.test.ts b/src/agents/pi-embedded-runner-extraparams.test.ts
index 404d4439da4..3b717d3ab96 100644
--- a/src/agents/pi-embedded-runner-extraparams.test.ts
+++ b/src/agents/pi-embedded-runner-extraparams.test.ts
@@ -490,6 +490,160 @@ describe("applyExtraParamsToAgent", () => {
     });
   });
 
+  it("passes configured websocket transport through stream options", () => {
+    const { calls, agent } = createOptionsCaptureAgent();
+    const cfg = {
+      agents: {
+        defaults: {
+          models: {
+            "openai-codex/gpt-5.3-codex": {
+              params: {
+                transport: "websocket",
+              },
+            },
+          },
+        },
+      },
+    };
+
+    applyExtraParamsToAgent(agent, cfg, "openai-codex", "gpt-5.3-codex");
+
+    const model = {
+      api: "openai-codex-responses",
+      provider: "openai-codex",
+      id: "gpt-5.3-codex",
+    } as Model<"openai-codex-responses">;
+    const context: Context = { messages: [] };
+    void agent.streamFn?.(model, context, {});
+
+    expect(calls).toHaveLength(1);
+    expect(calls[0]?.transport).toBe("websocket");
+  });
+
+  it("defaults Codex transport to auto (WebSocket-first)", () => {
+    const { calls, agent } = createOptionsCaptureAgent();
+
+    applyExtraParamsToAgent(agent, undefined, "openai-codex", "gpt-5.3-codex");
+
+    const model = {
+      api: "openai-codex-responses",
+      provider: "openai-codex",
+      id: "gpt-5.3-codex",
+    } as Model<"openai-codex-responses">;
+    const context: Context = { messages: [] };
+    void agent.streamFn?.(model, context, {});
+
+    expect(calls).toHaveLength(1);
+    expect(calls[0]?.transport).toBe("auto");
+  });
+
+  it("does not set transport defaults for non-Codex providers", () => {
+    const { calls, agent } = createOptionsCaptureAgent();
+
+    applyExtraParamsToAgent(agent, undefined, "openai", "gpt-5");
+
+    const model = {
+      api: "openai-responses",
+      provider: "openai",
+      id: "gpt-5",
+    } as Model<"openai-responses">;
+    const context: Context = { messages: [] };
+    void agent.streamFn?.(model, context, {});
+
+    expect(calls).toHaveLength(1);
+    expect(calls[0]?.transport).toBeUndefined();
+  });
+
+  it("allows forcing Codex transport to SSE", () => {
+    const { calls, agent } = createOptionsCaptureAgent();
+    const cfg = {
+      agents: {
+        defaults: {
+          models: {
+            "openai-codex/gpt-5.3-codex": {
+              params: {
+                transport: "sse",
+              },
+            },
+          },
+        },
+      },
+    };
+
+    applyExtraParamsToAgent(agent, cfg, "openai-codex", "gpt-5.3-codex");
+
+    const model = {
+      api: "openai-codex-responses",
+      provider: "openai-codex",
+      id: "gpt-5.3-codex",
+    } as Model<"openai-codex-responses">;
+    const context: Context = { messages: [] };
+    void agent.streamFn?.(model, context, {});
+
+    expect(calls).toHaveLength(1);
+    expect(calls[0]?.transport).toBe("sse");
+  });
+
+  it("lets runtime options override configured transport", () => {
+    const { calls, agent } = createOptionsCaptureAgent();
+    const cfg = {
+      agents: {
+        defaults: {
+          models: {
+            "openai-codex/gpt-5.3-codex": {
+              params: {
+                transport: "websocket",
+              },
+            },
+          },
+        },
+      },
+    };
+
+    applyExtraParamsToAgent(agent, cfg, "openai-codex", "gpt-5.3-codex");
+
+    const model = {
+      api: "openai-codex-responses",
+      provider: "openai-codex",
+      id: "gpt-5.3-codex",
+    } as Model<"openai-codex-responses">;
+    const context: Context = { messages: [] };
+    void agent.streamFn?.(model, context, { transport: "sse" });
+
+    expect(calls).toHaveLength(1);
+    expect(calls[0]?.transport).toBe("sse");
+  });
+
+  it("falls back to Codex default transport when configured value is invalid", () => {
+    const { calls, agent } = createOptionsCaptureAgent();
+    const cfg = {
+      agents: {
+        defaults: {
+          models: {
+            "openai-codex/gpt-5.3-codex": {
+              params: {
+                transport: "udp",
+              },
+            },
+          },
+        },
+      },
+    };
+
+    applyExtraParamsToAgent(agent, cfg, "openai-codex", "gpt-5.3-codex");
+
+    const model = {
+      api: "openai-codex-responses",
+      provider: "openai-codex",
+      id: "gpt-5.3-codex",
+    } as Model<"openai-codex-responses">;
+    const context: Context = { messages: [] };
+    void agent.streamFn?.(model, context, {});
+
+    expect(calls).toHaveLength(1);
+    expect(calls[0]?.transport).toBe("auto");
+  });
+
   it("disables prompt caching for non-Anthropic Bedrock models", () => {
     const { calls, agent } = createOptionsCaptureAgent();
 
diff --git a/src/agents/pi-embedded-runner/extra-params.ts b/src/agents/pi-embedded-runner/extra-params.ts
index dc1db5f7642..70662760235 100644
--- a/src/agents/pi-embedded-runner/extra-params.ts
+++ b/src/agents/pi-embedded-runner/extra-params.ts
@@ -117,6 +117,13 @@ function createStreamFnWithExtraParams(
   if (typeof extraParams.maxTokens === "number") {
     streamParams.maxTokens = extraParams.maxTokens;
   }
+  const transport = extraParams.transport;
+  if (transport === "sse" || transport === "websocket" || transport === "auto") {
+    streamParams.transport = transport;
+  } else if (transport != null) {
+    const transportSummary = typeof transport === "string" ? transport : typeof transport;
+    log.warn(`ignoring invalid transport param: ${transportSummary}`);
+  }
   const cacheRetention = resolveCacheRetention(extraParams, provider);
   if (cacheRetention) {
     streamParams.cacheRetention = cacheRetention;
@@ -234,6 +241,15 @@ function createOpenAIResponsesStoreWrapper(baseStreamFn: StreamFn | undefined):
   };
 }
 
+function createCodexDefaultTransportWrapper(baseStreamFn: StreamFn | undefined): StreamFn {
+  const underlying = baseStreamFn ?? streamSimple;
+  return (model, context, options) =>
+    underlying(model, context, {
+      ...options,
+      transport: options?.transport ?? "auto",
+    });
+}
+
 function isAnthropic1MModel(modelId: string): boolean {
   const normalized = modelId.trim().toLowerCase();
   return ANTHROPIC_1M_MODEL_PREFIXES.some((prefix) => normalized.startsWith(prefix));
@@ -652,6 +668,10 @@ export function applyExtraParamsToAgent(
     modelId,
     agentId,
   });
+  if (provider === "openai-codex") {
+    // Default Codex to WebSocket-first when nothing else specifies transport.
+    agent.streamFn = createCodexDefaultTransportWrapper(agent.streamFn);
+  }
   const override =
     extraParamsOverride && Object.keys(extraParamsOverride).length > 0
       ? Object.fromEntries(