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Code Mode uses Node by default when enabled. Select QuickJS when you need a hardened guest runtime. Both executors run the same plain JavaScript cells, expose the same typed tool discovery, and use the same exec and wait tools. Code Mode itself remains off by default.

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Choose an executor

Node’s node:vm is not a security boundary. The worker keeps guest computation off the Gateway event loop, but it shares the Gateway process’s operating-system privileges. Treat Node Code Mode as trusted host execution.
The intended guest API does not expose Node’s filesystem, networking, process, environment, or module-loading APIs. Module guards and a small set of globals help keep cells focused on tool orchestration; they do not make node:vm safe for hostile JavaScript. Use QuickJS when guest isolation is part of your threat model, and use a separate OS user, container, or host when you need a stronger host boundary. QuickJS provides a separate WASM guest with no ambient host access. It can still call powerful tools if your tool policy grants them. Calls made through the Code Mode tool bridge retain OpenClaw’s normal policy, approvals, hooks, and session ownership under either executor. These checks mediate tool calls; they cannot contain hostile code that escapes a Node VM context.

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Set the executor

In the web interface, open Settings → Agents & Tools → Labs and use Code Mode executor to choose Node.js (default) or QuickJS (isolated). Activation and executor selection are separate: choosing an executor does not enable Code Mode. To enable Code Mode with the default Node executor:
For hardened guest isolation, set executor: "quickjs" in the same object. The bundled plugin ID is code-mode-quickjs; selecting its executor needs no separate plugin enable step. Explicit executor selection activates this bundled runtime even when plugins.enabled is false or a restrictive plugins.allow list omits it. It does not enable other plugins. An explicit plugins.deny entry or plugins.entries.code-mode-quickjs.enabled: false still blocks it. An external plugin can supply the quickjs executor choice and remains subject to the full plugin activation policy. Enable exactly one owner for that choice. The selectable executor IDs are node and quickjs; node is owned by core. The selected executor must be available. If it is missing, disabled, denied, or cannot load, the run fails with runtime_unavailable; OpenClaw never silently switches to Node or broad direct tool exposure. Check plugin policy when a configured QuickJS executor is unavailable. Set agents.entries.<agent>.tools.codeMode.executor to override the global selection for one agent. An agent that omits it inherits the global choice. See Code Mode configuration for activation precedence and limits.

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Understand waits and limits

Each cell keeps its selected executor for its entire lifetime, including every wait. Changing configuration affects new cells; it does not move suspended JavaScript between engines or replay completed tool calls. Node retains its live worker context while suspended. QuickJS can release its worker after serializing the guest and restore the snapshot for wait. Both continuations are transient: completion, failure, cancellation, expiry, or Gateway shutdown releases them. Neither survives a Gateway restart. timeoutMs, output limits, pending-call limits, suspended-run capacity, and snapshotTtlSeconds apply to both executors. The historical snapshotTtlSeconds name also controls Node’s suspended-context lifetime. QuickJS additionally checks serialized VM state against maxSnapshotBytes. Node has no serialized VM snapshot, so that setting does not bound its live heap. Saved JSON results retain their shared memory/snapshot data allowance. memoryLimitBytes limits QuickJS guest memory. For Node, it configures a best-effort V8 worker heap budget across the old and young generations, subject to engine minimums. That budget includes worker runtime allocations and excludes external buffers; it is not a per-context heap measurement or security boundary. Neither executor’s setting caps total Gateway RSS. Worker overhead and host-side tool results also consume memory. A retained Node context can use more total host memory than a size-limited QuickJS snapshot. The shared limit of 64 suspended cells and reserved resume slots still applies; there is no separate global memory quota. See Code Mode internals for state ownership and retention.

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Upgrade an existing configuration

Doctor and eligible Gateway startup migrations replace an explicit runtime: "quickjs-wasi" with executor: "quickjs", preserving that explicit choice. An existing executor setting takes precedence when both fields are present. Activation and other limits remain unchanged. The migrated explicit QuickJS choice also works when generic plugins are disabled or allowlisted, without enabling unrelated plugins. An explicit denial of code-mode-quickjs still prevents execution. Configurations that did not explicitly select a runtime use the new Node default. Set executor: "quickjs" explicitly to retain hardened guest isolation. The retired runtime field is not a runtime alias; use openclaw doctor --fix for an older configuration.