openclaw/docs/plugins/codex-harness.md

title, summary, read_when

title	summary	read_when
Codex Harness	Run OpenClaw embedded agent turns through the bundled Codex app-server harness	You want to use the bundled Codex app-server harness You need Codex model refs and config examples You want to disable PI fallback for Codex-only deployments

Codex Harness

The bundled codex plugin lets OpenClaw run embedded agent turns through the Codex app-server instead of the built-in PI harness.

Use this when you want Codex to own the low-level agent session: model discovery, native thread resume, native compaction, and app-server execution. OpenClaw still owns chat channels, session files, model selection, tools, approvals, media delivery, and the visible transcript mirror.

Native Codex turns also respect the shared plugin hooks so prompt shims, compaction-aware automation, tool middleware, and lifecycle observers stay aligned with the PI harness:

• before_prompt_build
• before_compaction, after_compaction
• llm_input, llm_output
• tool_result, after_tool_call
• before_message_write
• agent_end

Bundled plugins can also register a Codex app-server extension factory to add async tool_result middleware.

The harness is off by default. It is selected only when the codex plugin is enabled and the resolved model is a codex/* model, or when you explicitly force embeddedHarness.runtime: "codex" or OPENCLAW_AGENT_RUNTIME=codex. If you never configure codex/*, existing PI, OpenAI, Anthropic, Gemini, local, and custom-provider runs keep their current behavior.

Pick the right model prefix

OpenClaw has separate routes for OpenAI and Codex-shaped access:

Model ref	Runtime path	Use when
openai/gpt-5.4	OpenAI provider through OpenClaw/PI plumbing	You want direct OpenAI Platform API access with OPENAI_API_KEY.
openai-codex/gpt-5.4	OpenAI Codex OAuth provider through PI	You want ChatGPT/Codex OAuth without the Codex app-server harness.
codex/gpt-5.4	Bundled Codex provider plus Codex harness	You want native Codex app-server execution for the embedded agent turn.

The Codex harness only claims codex/* model refs. Existing openai/*, openai-codex/*, Anthropic, Gemini, xAI, local, and custom provider refs keep their normal paths.

Harness selection is not a live session control. When an embedded turn runs, OpenClaw records the selected harness id on that session and keeps using it for later turns in the same session id. Change embeddedHarness config or OPENCLAW_AGENT_RUNTIME when you want future sessions to use another harness; use /new or /reset to start a fresh session before switching an existing conversation between PI and Codex. This avoids replaying one transcript through two incompatible native session systems.

Legacy sessions created before harness pins are treated as PI-pinned once they have transcript history. Use /new or /reset to opt that conversation into Codex after changing config.

/status shows the effective non-PI harness next to Fast, for example Fast · codex. The default PI harness is omitted.

Requirements

• OpenClaw with the bundled codex plugin available.
• Codex app-server 0.118.0 or newer.
• Codex auth available to the app-server process.

The plugin blocks older or unversioned app-server handshakes. That keeps OpenClaw on the protocol surface it has been tested against.

For live and Docker smoke tests, auth usually comes from OPENAI_API_KEY, plus optional Codex CLI files such as ~/.codex/auth.json and ~/.codex/config.toml. Use the same auth material your local Codex app-server uses.

Minimal config

Use codex/gpt-5.4, enable the bundled plugin, and force the codex harness:

{
  plugins: {
    entries: {
      codex: {
        enabled: true,
      },
    },
  },
  agents: {
    defaults: {
      model: "codex/gpt-5.4",
      embeddedHarness: {
        runtime: "codex",
        fallback: "none",
      },
    },
  },
}

If your config uses plugins.allow, include codex there too:

{
  plugins: {
    allow: ["codex"],
    entries: {
      codex: {
        enabled: true,
      },
    },
  },
}

Setting agents.defaults.model or an agent model to codex/<model> also auto-enables the bundled codex plugin. The explicit plugin entry is still useful in shared configs because it makes the deployment intent obvious.

Add Codex without replacing other models

Keep runtime: "auto" when you want Codex for codex/* models and PI for everything else:

{
  plugins: {
    entries: {
      codex: {
        enabled: true,
      },
    },
  },
  agents: {
    defaults: {
      model: {
        primary: "codex/gpt-5.4",
        fallbacks: ["openai/gpt-5.4", "anthropic/claude-opus-4-6"],
      },
      models: {
        "codex/gpt-5.4": { alias: "codex" },
        "codex/gpt-5.4-mini": { alias: "codex-mini" },
        "openai/gpt-5.4": { alias: "gpt" },
        "anthropic/claude-opus-4-6": { alias: "opus" },
      },
      embeddedHarness: {
        runtime: "auto",
        fallback: "pi",
      },
    },
  },
}

With this shape:

• /model codex or /model codex/gpt-5.4 uses the Codex app-server harness.
• /model gpt or /model openai/gpt-5.4 uses the OpenAI provider path.
• /model opus uses the Anthropic provider path.
• If a non-Codex model is selected, PI remains the compatibility harness.

Codex-only deployments

Disable PI fallback when you need to prove that every embedded agent turn uses the Codex harness:

{
  agents: {
    defaults: {
      model: "codex/gpt-5.4",
      embeddedHarness: {
        runtime: "codex",
        fallback: "none",
      },
    },
  },
}

Environment override:

OPENCLAW_AGENT_RUNTIME=codex \
OPENCLAW_AGENT_HARNESS_FALLBACK=none \
openclaw gateway run

With fallback disabled, OpenClaw fails early if the Codex plugin is disabled, the requested model is not a codex/* ref, the app-server is too old, or the app-server cannot start.

Per-agent Codex

You can make one agent Codex-only while the default agent keeps normal auto-selection:

{
  agents: {
    defaults: {
      embeddedHarness: {
        runtime: "auto",
        fallback: "pi",
      },
    },
    list: [
      {
        id: "main",
        default: true,
        model: "anthropic/claude-opus-4-6",
      },
      {
        id: "codex",
        name: "Codex",
        model: "codex/gpt-5.4",
        embeddedHarness: {
          runtime: "codex",
          fallback: "none",
        },
      },
    ],
  },
}

Use normal session commands to switch agents and models. /new creates a fresh OpenClaw session and the Codex harness creates or resumes its sidecar app-server thread as needed. /reset clears the OpenClaw session binding for that thread and lets the next turn resolve the harness from current config again.

Model discovery

By default, the Codex plugin asks the app-server for available models. If discovery fails or times out, it uses the bundled fallback catalog:

• codex/gpt-5.4
• codex/gpt-5.4-mini
• codex/gpt-5.2

You can tune discovery under plugins.entries.codex.config.discovery:

{
  plugins: {
    entries: {
      codex: {
        enabled: true,
        config: {
          discovery: {
            enabled: true,
            timeoutMs: 2500,
          },
        },
      },
    },
  },
}

Disable discovery when you want startup to avoid probing Codex and stick to the fallback catalog:

{
  plugins: {
    entries: {
      codex: {
        enabled: true,
        config: {
          discovery: {
            enabled: false,
          },
        },
      },
    },
  },
}

App-server connection and policy

By default, the plugin starts Codex locally with:

codex app-server --listen stdio://

By default, OpenClaw starts local Codex harness sessions in YOLO mode: approvalPolicy: "never", approvalsReviewer: "user", and sandbox: "danger-full-access". This is the trusted local operator posture used for autonomous heartbeats: Codex can use shell and network tools without stopping on native approval prompts that nobody is around to answer.

To opt in to Codex guardian-reviewed approvals, set appServer.mode: "guardian":

{
  plugins: {
    entries: {
      codex: {
        enabled: true,
        config: {
          appServer: {
            mode: "guardian",
            serviceTier: "fast",
          },
        },
      },
    },
  },
}

Guardian is a native Codex approval reviewer. When Codex asks to leave the sandbox, write outside the workspace, or add permissions like network access, Codex routes that approval request to a reviewer subagent instead of a human prompt. The reviewer applies Codex's risk framework and approves or denies the specific request. Use Guardian when you want more guardrails than YOLO mode but still need unattended agents to make progress.

The guardian preset expands to approvalPolicy: "on-request", approvalsReviewer: "guardian_subagent", and sandbox: "workspace-write". Individual policy fields still override mode, so advanced deployments can mix the preset with explicit choices.

For an already-running app-server, use WebSocket transport:

{
  plugins: {
    entries: {
      codex: {
        enabled: true,
        config: {
          appServer: {
            transport: "websocket",
            url: "ws://127.0.0.1:39175",
            authToken: "${CODEX_APP_SERVER_TOKEN}",
            requestTimeoutMs: 60000,
          },
        },
      },
    },
  },
}

Supported appServer fields:

Field	Default	Meaning
transport	"stdio"	"stdio" spawns Codex; "websocket" connects to url.
command	"codex"	Executable for stdio transport.
args	["app-server", "--listen", "stdio://"]	Arguments for stdio transport.
url	unset	WebSocket app-server URL.
authToken	unset	Bearer token for WebSocket transport.
headers	{}	Extra WebSocket headers.
requestTimeoutMs	60000	Timeout for app-server control-plane calls.
mode	"yolo"	Preset for YOLO or guardian-reviewed execution.
approvalPolicy	"never"	Native Codex approval policy sent to thread start/resume/turn.
sandbox	"danger-full-access"	Native Codex sandbox mode sent to thread start/resume.
approvalsReviewer	"user"	Use "guardian_subagent" to let Codex Guardian review prompts.
serviceTier	unset	Optional Codex app-server service tier: "fast", "flex", or null. Invalid legacy values are ignored.

The older environment variables still work as fallbacks for local testing when the matching config field is unset:

• OPENCLAW_CODEX_APP_SERVER_BIN
• OPENCLAW_CODEX_APP_SERVER_ARGS
• OPENCLAW_CODEX_APP_SERVER_MODE=yolo|guardian
• OPENCLAW_CODEX_APP_SERVER_APPROVAL_POLICY
• OPENCLAW_CODEX_APP_SERVER_SANDBOX

OPENCLAW_CODEX_APP_SERVER_GUARDIAN=1 was removed. Use plugins.entries.codex.config.appServer.mode: "guardian" instead, or OPENCLAW_CODEX_APP_SERVER_MODE=guardian for one-off local testing. Config is preferred for repeatable deployments because it keeps the plugin behavior in the same reviewed file as the rest of the Codex harness setup.

Common recipes

Local Codex with default stdio transport:

{
  plugins: {
    entries: {
      codex: {
        enabled: true,
      },
    },
  },
}

Codex-only harness validation, with PI fallback disabled:

{
  embeddedHarness: {
    fallback: "none",
  },
  plugins: {
    entries: {
      codex: {
        enabled: true,
      },
    },
  },
}

Guardian-reviewed Codex approvals:

{
  plugins: {
    entries: {
      codex: {
        enabled: true,
        config: {
          appServer: {
            mode: "guardian",
            approvalPolicy: "on-request",
            approvalsReviewer: "guardian_subagent",
            sandbox: "workspace-write",
          },
        },
      },
    },
  },
}

Remote app-server with explicit headers:

{
  plugins: {
    entries: {
      codex: {
        enabled: true,
        config: {
          appServer: {
            transport: "websocket",
            url: "ws://gateway-host:39175",
            headers: {
              "X-OpenClaw-Agent": "main",
            },
          },
        },
      },
    },
  },
}

Model switching stays OpenClaw-controlled. When an OpenClaw session is attached to an existing Codex thread, the next turn sends the currently selected codex/* model, provider, approval policy, sandbox, and service tier to app-server again. Switching from codex/gpt-5.4 to codex/gpt-5.2 keeps the thread binding but asks Codex to continue with the newly selected model.

Codex command

The bundled plugin registers /codex as an authorized slash command. It is generic and works on any channel that supports OpenClaw text commands.

Common forms:

• /codex status shows live app-server connectivity, models, account, rate limits, MCP servers, and skills.
• /codex models lists live Codex app-server models.
• /codex threads [filter] lists recent Codex threads.
• /codex resume <thread-id> attaches the current OpenClaw session to an existing Codex thread.
• /codex compact asks Codex app-server to compact the attached thread.
• /codex review starts Codex native review for the attached thread.
• /codex account shows account and rate-limit status.
• /codex mcp lists Codex app-server MCP server status.
• /codex skills lists Codex app-server skills.

/codex resume writes the same sidecar binding file that the harness uses for normal turns. On the next message, OpenClaw resumes that Codex thread, passes the currently selected OpenClaw codex/* model into app-server, and keeps extended history enabled.

The command surface requires Codex app-server 0.118.0 or newer. Individual control methods are reported as unsupported by this Codex app-server if a future or custom app-server does not expose that JSON-RPC method.

Tools, media, and compaction

The Codex harness changes the low-level embedded agent executor only.

OpenClaw still builds the tool list and receives dynamic tool results from the harness. Text, images, video, music, TTS, approvals, and messaging-tool output continue through the normal OpenClaw delivery path.

Codex MCP tool approval elicitations are routed through OpenClaw's plugin approval flow when Codex marks _meta.codex_approval_kind as "mcp_tool_call"; other elicitation and free-form input requests still fail closed.

When the selected model uses the Codex harness, native thread compaction is delegated to Codex app-server. OpenClaw keeps a transcript mirror for channel history, search, /new, /reset, and future model or harness switching. The mirror includes the user prompt, final assistant text, and lightweight Codex reasoning or plan records when the app-server emits them. Today, OpenClaw only records native compaction start and completion signals. It does not yet expose a human-readable compaction summary or an auditable list of which entries Codex kept after compaction.

Media generation does not require PI. Image, video, music, PDF, TTS, and media understanding continue to use the matching provider/model settings such as agents.defaults.imageGenerationModel, videoGenerationModel, pdfModel, and messages.tts.

Troubleshooting

Codex does not appear in /model: enable plugins.entries.codex.enabled, set a codex/* model ref, or check whether plugins.allow excludes codex.

OpenClaw uses PI instead of Codex: if no Codex harness claims the run, OpenClaw may use PI as the compatibility backend. Set embeddedHarness.runtime: "codex" to force Codex selection while testing, or embeddedHarness.fallback: "none" to fail when no plugin harness matches. Once Codex app-server is selected, its failures surface directly without extra fallback config.

The app-server is rejected: upgrade Codex so the app-server handshake reports version 0.118.0 or newer.

Model discovery is slow: lower plugins.entries.codex.config.discovery.timeoutMs or disable discovery.

WebSocket transport fails immediately: check appServer.url, authToken, and that the remote app-server speaks the same Codex app-server protocol version.

A non-Codex model uses PI: that is expected. The Codex harness only claims codex/* model refs.

Related

• Agent Harness Plugins
• Model Providers
• Configuration Reference
• Testing