--- summary: "Runtime boundaries, hooks, tools, permissions, and diagnostics for the Codex harness" title: "Codex harness runtime" read_when: - You need the Codex harness runtime support contract - You are debugging native Codex tools, hooks, compaction, or feedback upload - You are changing plugin behavior across PI and Codex harness turns --- This page documents the runtime contract for Codex harness turns. For setup and routing, start with [Codex harness](/plugins/codex-harness). For config fields, see [Codex harness reference](/plugins/codex-harness-reference). ## Overview Codex mode is not PI with a different model call underneath. Codex owns more of the native model loop, and OpenClaw adapts its plugin, tool, session, and diagnostic surfaces around that boundary. OpenClaw still owns channel routing, session files, visible message delivery, OpenClaw dynamic tools, approvals, media delivery, and a transcript mirror. Codex owns the canonical native thread, native model loop, native tool continuation, and native compaction. ## Thread bindings and model changes When an OpenClaw session is attached to an existing Codex thread, the next turn sends the currently selected OpenAI model, approval policy, sandbox, and service tier to app-server again. Switching from `openai/gpt-5.5` to `openai/gpt-5.2` keeps the thread binding but asks Codex to continue with the newly selected model. ## Visible replies and heartbeats When a source chat turn runs through the Codex harness, visible replies default to the OpenClaw `message` tool if the deployment has not explicitly configured `messages.visibleReplies`. The agent can still finish its Codex turn privately; it only posts to the channel when it calls `message(action="send")`. Set `messages.visibleReplies: "automatic"` to keep direct-chat final replies on the legacy automatic delivery path. Codex heartbeat turns also get `heartbeat_respond` in the searchable OpenClaw tool catalog by default, so the agent can record whether the wake should stay quiet or notify without encoding that control flow in final text. Heartbeat-specific initiative guidance is sent as a Codex collaboration-mode developer instruction on the heartbeat turn itself. Ordinary chat turns restore Codex Default mode instead of carrying heartbeat philosophy in their normal runtime prompt. ## Hook boundaries The Codex harness has three hook layers: | Layer | Owner | Purpose | | ------------------------------------- | ------------------------ | ------------------------------------------------------------------- | | OpenClaw plugin hooks | OpenClaw | Product/plugin compatibility across PI and Codex harnesses. | | Codex app-server extension middleware | OpenClaw bundled plugins | Per-turn adapter behavior around OpenClaw dynamic tools. | | Codex native hooks | Codex | Low-level Codex lifecycle and native tool policy from Codex config. | OpenClaw does not use project or global Codex `hooks.json` files to route OpenClaw plugin behavior. For the supported native tool and permission bridge, OpenClaw injects per-thread Codex config for `PreToolUse`, `PostToolUse`, `PermissionRequest`, and `Stop`. When Codex app-server approvals are enabled, meaning `approvalPolicy` is not `"never"`, the default injected native hook config omits `PermissionRequest` so Codex's app-server reviewer and OpenClaw's approval bridge handle real escalations after review. Operators can explicitly add `permission_request` to `nativeHookRelay.events` when they need the compatibility relay. Other Codex hooks such as `SessionStart` and `UserPromptSubmit` remain Codex-level controls. They are not exposed as OpenClaw plugin hooks in the v1 contract. For OpenClaw dynamic tools, OpenClaw executes the tool after Codex asks for the call, so OpenClaw fires the plugin and middleware behavior it owns in the harness adapter. For Codex-native tools, Codex owns the canonical tool record. OpenClaw can mirror selected events, but it cannot rewrite the native Codex thread unless Codex exposes that operation through app-server or native hook callbacks. Compaction and LLM lifecycle projections come from Codex app-server notifications and OpenClaw adapter state, not native Codex hook commands. OpenClaw's `before_compaction`, `after_compaction`, `llm_input`, and `llm_output` events are adapter-level observations, not byte-for-byte captures of Codex's internal request or compaction payloads. Codex native `hook/started` and `hook/completed` app-server notifications are projected as `codex_app_server.hook` agent events for trajectory and debugging. They do not invoke OpenClaw plugin hooks. ## V1 support contract Supported in Codex runtime v1: | Surface | Support | Why | | --------------------------------------------- | -------------------------------------------------------------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | OpenAI model loop through Codex | Supported | Codex app-server owns the OpenAI turn, native thread resume, and native tool continuation. | | OpenClaw channel routing and delivery | Supported | Telegram, Discord, Slack, WhatsApp, iMessage, and other channels stay outside the model runtime. | | OpenClaw dynamic tools | Supported | Codex asks OpenClaw to execute these tools, so OpenClaw stays in the execution path. | | Prompt and context plugins | Supported | OpenClaw builds prompt overlays and projects context into the Codex turn before starting or resuming the thread. | | Context engine lifecycle | Supported | Assemble, ingest, after-turn maintenance, and context-engine compaction coordination run for Codex turns. | | Dynamic tool hooks | Supported | `before_tool_call`, `after_tool_call`, and tool-result middleware run around OpenClaw-owned dynamic tools. | | Lifecycle hooks | Supported as adapter observations | `llm_input`, `llm_output`, `agent_end`, `before_compaction`, and `after_compaction` fire with honest Codex-mode payloads. | | Final-answer revision gate | Supported through native hook relay | Codex `Stop` is relayed to `before_agent_finalize`; `revise` asks Codex for one more model pass before finalization. | | Native shell, patch, and MCP block or observe | Supported through native hook relay | Codex `PreToolUse` and `PostToolUse` are relayed for committed native tool surfaces, including MCP payloads on Codex app-server `0.125.0` or newer. Blocking is supported; argument rewriting is not. | | Native permission policy | Supported through Codex app-server approvals and compatibility native hook relay | Codex app-server approval requests route through OpenClaw after Codex review. The `PermissionRequest` native hook relay is opt-in for native approval modes because Codex emits it before guardian review. | | App-server trajectory capture | Supported | OpenClaw records the request it sent to app-server and the app-server notifications it receives. | Not supported in Codex runtime v1: | Surface | V1 boundary | Future path | | --------------------------------------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------- | ----------------------------------------------------------------------------------------- | | Native tool argument mutation | Codex native pre-tool hooks can block, but OpenClaw does not rewrite Codex-native tool arguments. | Requires Codex hook/schema support for replacement tool input. | | Editable Codex-native transcript history | Codex owns canonical native thread history. OpenClaw owns a mirror and can project future context, but should not mutate unsupported internals. | Add explicit Codex app-server APIs if native thread surgery is needed. | | `tool_result_persist` for Codex-native tool records | That hook transforms OpenClaw-owned transcript writes, not Codex-native tool records. | Could mirror transformed records, but canonical rewrite needs Codex support. | | Rich native compaction metadata | OpenClaw observes compaction start and completion, but does not receive a stable kept/dropped list, token delta, or summary payload. | Needs richer Codex compaction events. | | Compaction intervention | Current OpenClaw compaction hooks are notification-level in Codex mode. | Add Codex pre/post compaction hooks if plugins need to veto or rewrite native compaction. | | Byte-for-byte model API request capture | OpenClaw can capture app-server requests and notifications, but Codex core builds the final OpenAI API request internally. | Needs a Codex model-request tracing event or debug API. | ## Native permissions and MCP elicitations For `PermissionRequest`, OpenClaw only returns explicit allow or deny decisions when policy decides. A no-decision result is not an allow. Codex treats it as no hook decision and falls through to its own guardian or user approval path. Codex app-server approval modes omit this native hook by default. This behavior applies when `permission_request` is explicitly included in `nativeHookRelay.events` or a compatibility runtime installs it. When an operator chooses `allow-always` for a Codex native permission request, OpenClaw remembers that exact provider/session/tool input/cwd fingerprint for a bounded session window. The remembered decision is intentionally exact-match only: a changed command, arguments, tool payload, or cwd creates a fresh approval. Codex MCP tool approval elicitations are routed through OpenClaw's plugin approval flow when Codex marks `_meta.codex_approval_kind` as `"mcp_tool_call"`. Codex `request_user_input` prompts are sent back to the originating chat, and the next queued follow-up message answers that native server request instead of being steered as extra context. Other MCP elicitation requests fail closed. ## Queue steering Active-run queue steering maps onto Codex app-server `turn/steer`. With the default `messages.queue.mode: "steer"`, OpenClaw batches queued chat messages for the configured quiet window and sends them as one `turn/steer` request in arrival order. Legacy `queue` mode sends separate `turn/steer` requests. Codex review and manual compaction turns can reject same-turn steering. In that case, OpenClaw uses the follow-up queue when the selected mode allows fallback. See [Steering queue](/concepts/queue-steering). ## Codex feedback upload When `/diagnostics [note]` is approved for a session using the native Codex harness, OpenClaw also calls Codex app-server `feedback/upload` for relevant Codex threads. The upload asks app-server to include logs for each listed thread and spawned Codex subthreads when available. The upload goes through Codex's normal feedback path to OpenAI servers. If Codex feedback is disabled in that app-server, the command returns the app-server error. The completed diagnostics reply lists the channels, OpenClaw session ids, Codex thread ids, and local `codex resume ` commands for the threads that were sent. If you deny or ignore the approval, OpenClaw does not print those Codex ids and does not send Codex feedback. The upload does not replace the local Gateway diagnostics export. See [Diagnostics export](/gateway/diagnostics) for the approval, privacy, local bundle, and group-chat behavior. Use `/codex diagnostics [note]` only when you specifically want the Codex feedback upload for the currently attached thread without the full Gateway diagnostics bundle. ## Compaction and transcript mirror 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. Because Codex owns the canonical native thread, `tool_result_persist` does not currently rewrite Codex-native tool result records. It only applies when OpenClaw is writing an OpenClaw-owned session transcript tool result. ## Media and delivery OpenClaw continues to own media delivery and media provider selection. Image, video, music, PDF, TTS, and media understanding use matching provider/model settings such as `agents.defaults.imageGenerationModel`, `videoGenerationModel`, `pdfModel`, and `messages.tts`. Text, images, video, music, TTS, approvals, and messaging-tool output continue through the normal OpenClaw delivery path. Media generation does not require PI. ## Related - [Codex harness](/plugins/codex-harness) - [Codex harness reference](/plugins/codex-harness-reference) - [Native Codex plugins](/plugins/codex-native-plugins) - [Plugin hooks](/plugins/hooks) - [Agent harness plugins](/plugins/sdk-agent-harness) - [Diagnostics export](/gateway/diagnostics) - [Trajectory export](/tools/trajectory)