Agent harness runtime configuration

Operator configuration: turning on the bundled native Codex mode, and pinning provider, model, or per-agent runtime policy so a missing harness fails instead of routing through the embedded runtime. Part of the Agent harness plugins reference.

Native Codex harness mode

The bundled codex harness is the native Codex mode for embedded OpenClaw agent turns. Enable the bundled codex plugin first, and include codex in plugins.allow if your config uses a restrictive allowlist. Native app-server configs should use openai/gpt-*; OpenAI agent turns select the Codex harness only when the effective route declares Codex compatibility. Legacy Codex model refs should be repaired with openclaw doctor --fix, and legacy codex/* model refs remain compatibility aliases for the native harness.

When this mode runs, Codex owns the native thread id, resume behavior, compaction, and app-server execution. OpenClaw still owns the chat channel, visible transcript mirror, tool policy, approvals, media delivery, and session selection. Use provider/model agentRuntime.id: "codex" to require a registered Codex harness. Unsupported routes/auth fail closed unless the harness declares an exact-request fallback before execution. Codex runtime failures are not retried through another runtime.

Runtime strictness

By default, OpenClaw uses auto provider/model runtime policy: registered plugin harnesses can claim compatible effective routes, and the embedded runtime handles the turn when none match. A provider/model prefix alone never selects a harness. Use an explicit provider/model plugin runtime such as agentRuntime.id: "codex" when missing harness selection should fail instead of routing through the embedded runtime. Explicit selection does not make an incompatible route compatible. Selected plugin harness failures always fail hard. This does not block an explicit provider/model agentRuntime.id: "openclaw".

To request Codex for embedded runs:

{  "models": {    "providers": {      "openai": {        "agentRuntime": {          "id": "codex"        }      }    }  },  "agents": {    "defaults": {      "model": "openai/gpt-5.6-sol"    }  }}

If you want a CLI backend for one canonical model, put the runtime on that model entry:

{  "agents": {    "defaults": {      "model": "anthropic/claude-opus-5",      "models": {        "anthropic/claude-opus-5": {          "agentRuntime": {            "id": "claude-cli"          }        }      }    }  }}

Per-agent overrides use the same model-scoped shape:

{  "agents": {    "entries": {      "codex-only": {        "default": true,        "model": "openai/gpt-5.6-sol",        "models": {          "openai/gpt-5.6-sol": {            "agentRuntime": { "id": "codex" }          }        }      }    }  }}

Legacy whole-agent runtime examples like this are ignored:

{  "agents": {    "defaults": {      "agentRuntime": {        "id": "codex"      }    }  }}

With an explicit plugin runtime, a session fails early when the requested harness is not registered or rejects the resolved provider/model without a declared fallback. An authored transport override may select OpenClaw through that fallback even with an explicit runtime. To prove native execution, inspect the actual harness in the completed result; configured intent alone is not proof.

This setting only controls the embedded agent harness. It does not disable image, video, music, TTS, PDF, or other provider-specific model routing.