Swarm

Swarm is an experimental way to orchestrate many sub-agents from a Code Mode script. It is enabled by default, with an explicit opt-out. Use normal JavaScript or TypeScript control flow such as Promise.all, while, and if to fan out work, collect results, and make decisions.

There is no graph DSL and no separate workflow format. The program is the orchestration. Swarm adds awaitable collector children, structured results, bounded concurrency, and progress reporting to that program.

Enable Swarm

Swarm needs no enablement setting. Omitted tools.swarm, an empty object, or an object that sets only limits all leave Swarm enabled. Code Mode remains separately opt-in, and normal tool policy still applies. Existing Codex sessions can retain an older tool catalog; see the fresh-session guidance below.

To opt out, turn off Settings → Agents & Tools → Labs → Swarm in the Control UI. The switch saves tools.swarm.enabled: false immediately and applies to future runs without restarting the Gateway. Or set the boolean shorthand in openclaw.json:

{
  tools: {
    swarm: false,
  },
}

swarm: { enabled: false } has the same effect while preserving configured limits. To re-enable Swarm, remove the explicit opt-out, set swarm: true or swarm: { enabled: true }, or turn the Labs switch back on.

To tune the limits, use object form. These are the defaults; you only need to include values you want to change:

{
  tools: {
    swarm: {
      maxConcurrent: 8,
      maxChildrenPerGroup: 50,
      maxTotalPerGroup: 200,
      waitTimeoutSecondsMax: 600,
      defaultAgentId: "",
    },
  },
}

Field	Default	Description
enabled	true	Enables collector features subject to tool policy; set false to opt out. Code Mode has additional requirements below.
maxConcurrent	8	Maximum collector children running concurrently in one swarm group. Additional accepted children queue in FIFO order.
maxChildrenPerGroup	50	Maximum live collector children in one group.
maxTotalPerGroup	200	Maximum collector children a group may spawn over its lifetime. This is the runaway-spawn backstop.
waitTimeoutSecondsMax	600	Maximum timeout accepted by one agents_wait call. The call default is 30 seconds.
defaultAgentId	""	Target agent used when a spawn omits agentId. An empty value uses the requesting agent. Existing sub-agent allowlists apply.

Numeric values must be positive integers. OpenClaw bounds maxConcurrent to 1–1000, maxChildrenPerGroup to 1–10000, maxTotalPerGroup to 1–100000, and waitTimeoutSecondsMax to 1–86400.

You can override Swarm for one configured agent with agents.entries.*.tools.swarm. Per-agent values merge over the top-level setting. An agent’s false or { enabled: false } disables Swarm for that agent; true or { enabled: true } enables it even if globally disabled. A limits-only per-agent object inherits global enablement, so it does not re-enable a global false.

Requirements

To use the agents.run, phase, and log guest globals, enable OpenClaw Code Mode and leave Swarm enabled:

{
  tools: {
    codeMode: true,
  },
}

Code Mode exposes these globals, API.read("agents.d.ts"), and Swarm prompt hints only when its catalog contains the native OpenClaw sessions_spawn tool and the run’s execution allowlist permits it. An MCP tool with the same name does not qualify. Tool profiles, allow/deny policy, provider rules, and sandbox policy can remove the native tool. If the Swarm API is absent, check Code Mode activation and Sub-agents.

Code Mode waits for collector results internally; its agents.run() API does not require the standalone agents_wait tool to be allowed. The low-level tool flow needs both sessions_spawn and agents_wait allowed. Enabling Swarm never grants tools or bypasses policy.

defaultAgentId and per-run agentId values must name a configured target permitted by the requester’s subagents.allowAgents policy. OpenClaw rejects an unknown or disallowed target instead of falling back to another agent.

Write a Swarm script

When the requirements are met, Code Mode exposes this guest API:

type AgentRunOptions = {
  label?: string;
  model?: string;
  thinking?: string;
  fastMode?: boolean | "auto";
  agentId?: string;
  schema?: Record<string, unknown>;
  phase?: string;
};

agents.run(prompt: string, options?: AgentRunOptions & { schema?: undefined }): Promise<string>;
agents.run<T>(prompt: string, options: AgentRunOptions & { schema: Record<string, unknown> }): Promise<T>;
phase(title: string): void;
log(message: string): void;

Without schema, agents.run() resolves to the child’s final text. With a JSON Schema, it resolves to the value submitted through the child’s structured_output tool. A failed, killed, timed-out, or schema-invalid child rejects the promise with a SwarmAgentError. Read the exact generated declarations and short orchestration idioms from API.read("agents.d.ts") inside Code Mode.

Use label for a recognizable child name in the dashboard and sidebar. Use phase in the options to publish a phase immediately before that child starts, or call phase() when several children belong to the same stage. log() publishes a short progress note. Progress calls are fire-and-forget; they do not delay the script if the UI is unavailable.

Fan out in parallel with structured results

This example launches one researcher per topic, waits for all of them, then asks a final child to synthesize their structured reports:

const reportSchema = {
  type: "object",
  properties: {
    finding: { type: "string" },
    evidence: { type: "array", items: { type: "string" } },
    confidence: { type: "number" },
  },
  required: ["finding", "evidence", "confidence"],
  additionalProperties: false,
};

const topics = ["authentication", "storage", "recovery"];
phase("Independent review");

const reports = await Promise.all(
  topics.map((topic) =>
    agents.run(`Review the ${topic} path. Return one finding with evidence.`, {
      label: `review-${topic}`,
      thinking: "high",
      fastMode: "auto",
      schema: reportSchema,
    }),
  ),
);

phase("Synthesis");
log(`Collected ${reports.length} independent reports.`);

return await agents.run(
  `Reconcile these reports and explain disagreements:\n${JSON.stringify(reports)}`,
  { label: "synthesis" },
);

Promise.all is the fan-out and fan-in boundary. OpenClaw starts up to maxConcurrent children for the group and queues the rest in submission order.

Code Mode separately bounds concurrent guest bridge calls with tools.codeMode.maxPendingToolCalls (default 16, maximum 128). Swarm launches, progress notes, and result waits queue automatically when those slots are full. Queued requests retain their original arguments across snapshot resumes; stopping the run discards requests that have not been admitted. maxConcurrent still limits running children, and group child limits still apply. Raw tool calls do not use this Swarm queue and must remain within the bridge-call limit.

Loop on a decision gate

Use a bounded while loop when each pass decides whether another pass is needed:

const gateSchema = {
  type: "object",
  properties: {
    ready: { type: "boolean" },
    reason: { type: "string" },
    nextAction: { type: "string" },
  },
  required: ["ready", "reason", "nextAction"],
  additionalProperties: false,
};

let pass = 0;
let decision = { ready: false, reason: "Not checked", nextAction: "Review" };

while (!decision.ready && pass < 4) {
  pass += 1;
  phase(`Decision pass ${pass}`);
  decision = await agents.run(
    `Check whether the release evidence is complete. Previous decision: ${JSON.stringify(decision)}`,
    {
      label: `release-gate-${pass}`,
      schema: gateSchema,
    },
  );
  log(decision.reason);
}

if (!decision.ready) {
  throw new Error(`Gate still closed after ${pass} passes: ${decision.nextAction}`);
}

return decision;

Always bound decision loops. maxTotalPerGroup is the final safety backstop, not a substitute for a clear stopping condition.

Process the first child that finishes

agents.run() returns an ordinary promise, so Promise.race can react to the first Code Mode child. For harnesses that call the lower-level tools, agents_wait provides the same first-completion boundary: it returns as soon as at least one requested run completes, or when the bounded timeout expires. See Use Swarm from other harnesses for the complete drain loop.

How collector children behave

Collector children are ordinary isolated sub-agent sessions with a different completion path. They write a durable collector result for the parent to await instead of announcing or steering a reply back into the parent session. The accepted spawn receipt describes this path: collect the result with agents_wait, or await agents.run() in OpenClaw Code Mode. Do not use sessions_yield to wait for collectors; they do not send completion notifications.

The target agent resolves in this order:

1. agentId on the spawn or agents.run() call.
2. tools.swarm.defaultAgentId.
3. The requesting agent.

A dedicated, lean worker agent is useful when swarm children need a smaller tool surface, cheaper model, or tighter sandbox policy. OpenClaw does not ship a built-in worker agent id; configure one before naming it as the default. Harden that worker with tools.swarm: false in its per-agent configuration so it can be spawned but cannot start swarms from its own top-level sessions:

{
  tools: { swarm: { enabled: true, defaultAgentId: "worker" } },
  agents: {
    entries: {
      main: {
        default: true,
        subagents: { allowAgents: ["worker"] },
      },
      worker: { tools: { swarm: false } },
    },
  },
}

Collector approvals fail closed. A child never opens an operator approval prompt. A tool action that would require approval is denied, and the child can report that denial in its result so the script can decide what to do next.

For structured output, OpenClaw adds a synthetic structured_output tool to the child and validates its payload against the supplied JSON Schema. An invalid payload gets one corrective nudge. If no payload is submitted, or the retry still does not validate, the collector completion keeps the child’s raw text, leaves structured unset, and includes schemaError. The low-level agents_wait result exposes those fields for explicit recovery logic.

Children are leaves

Swarm children are leaves by default. The universal agents.defaults.subagents.maxSpawnDepth guard prevents a child from spawning its own children at the default depth of 1. The usual orchestration idiom is to return work to the parent, not spawn more work from a child:

const plan = await agents.run("Plan this job as independent tasks.", {
  schema: {
    type: "object",
    properties: { tasks: { type: "array", items: { type: "string" } } },
    required: ["tasks"],
    additionalProperties: false,
  },
});
return await Promise.all(plan.tasks.map((task) => agents.run(task)));

Nested sub-agents are an operator opt-in through agents.defaults.subagents.maxSpawnDepth and are discouraged for Swarm. Group caps, budgets, and observability all assume flat collector groups.

Every child has one admission owner. Announce and interactive children use agents.defaults.subagents.maxChildrenPerAgent (default 5) and do not count collector children. Collector children use only maxChildrenPerGroup and maxTotalPerGroup; they do not consume the per-session child budget. The spawn depth guard still applies to both modes.

After admission, children above maxConcurrent queue FIFO within their swarm group, nested inside the global sub-agent lane. These concurrency layers queue work rather than rejecting it. A collector spawn that exceeds either group cap is rejected with the relevant config key in the error.

Observe a Swarm

Keep the parent session open in Chat while a swarm is active. The Control UI and native Android, iOS, and macOS chat surfaces show a compact Swarm progress widget between the transcript and composer.

In the Control UI, each active collector group appears as a card with a completion count and phase progress segments. Hover over a card or focus it with the keyboard to reveal a list of child names, status icons, and run durations.

Native Android, iOS, and macOS chat surfaces show phase-grouped grids of child status markers, capped at 256 markers per phase with an overflow count for additional children. Accessible labels identify each child and its queued, running, done, or failed status.

All clients present killed and timed-out children as failed. Each group leaves the widget when none of its children are queued or running, and the widget disappears when no active groups remain.

The session sidebar keeps the normal parent/child tree. Expand the parent row to inspect a collector child or open its transcript without losing the swarm hierarchy.

Collector results remain waitable until their group is archived. After every member reaches its retention deadline, OpenClaw archives the group’s children as a batch so completed swarms do not remain in the live session tree.

Stop a Swarm

Use Stop in the parent chat to cancel a running swarm. A Stop targeting a specific parent run also cancels its associated collector children and their nested descendants. Collector mode changes result delivery, not cancellation scope. Successful cancellation prevents selected queued children from starting as running siblings stop; it does not cancel work from unrelated parent turns.

If Stop reports incomplete descendant cancellation, inspect the remaining work on the Tasks page and retry cancellation for those children. A stopped parent alone does not confirm that every child stopped, and a cancellation acknowledgment does not promise instantaneous runtime cleanup.

Already-accepted children remain independent when the parent completes normally, yields, or times out. If the parent is no longer active, cancel the child tasks directly. See Sub-agent stopping for exact-run and session-wide Stop scopes.

Use Swarm from other harnesses

You can use Swarm without OpenClaw Code Mode. Its core tools are harness-independent: start collector children with sessions_spawn({ collect: true }) and drain them with bounded agents_wait calls. Both tools must be allowed by the effective tool policy; default-on Swarm does not add them to a restrictive tool profile or allowlist.

Codex Code Mode automatically exposes eligible dynamic OpenClaw tools under tools.*. It does not use OpenClaw’s QuickJS guest API or require tools.codeMode, but tools.swarm must still be enabled. Codex harness agents_wait calls support the full 600-second timeout.

Codex records its dynamic tool catalog when a native thread starts. A thread created without agents_wait cannot gain that reader just by enabling Swarm or upgrading OpenClaw, so collector spawn fields remain unavailable on that thread. For an ordinary unlocked chat, use /new or /reset to start with current tools. For a supervised, model-locked Chat, open the Control UI’s global New Session page and select a concrete Codex-backed model to start a separate ordinary session. Keep the supervised Chat intact: /new, /reset, and parent-linked New chat are blocked there. The new session still needs a tool policy that permits both collector tools.

With the currently supported Codex runtime, dynamic OpenClaw tool results reach Code Mode as JSON text. Parse each result before reading fields. Codex also serializes dynamic tool calls, so Promise.all does not submit several sessions_spawn calls concurrently. Launch collectors in a bounded loop; already-accepted children can still run while later launches are submitted.

function parseToolResult(value) {
  if (typeof value !== "string") return value;
  return JSON.parse(value);
}

const tasks = [
  "Check the authentication path.",
  "Check the storage path.",
  "Check the recovery path.",
];
const launches = [];

for (const [index, task] of tasks.entries()) {
  const launch = parseToolResult(
    await tools.sessions_spawn({
      task,
      collect: true,
      label: `review-${index + 1}`,
    }),
  );
  if (launch.status !== "accepted") {
    throw new Error(launch.error ?? "Collector spawn was not accepted.");
  }
  launches.push(launch);
}

const pending = new Set(launches.map((launch) => launch.runId));
const completed = [];

while (pending.size > 0) {
  const ids = [...pending].slice(0, 1000);
  const batch = parseToolResult(
    await tools.agents_wait({
      ids,
      timeoutSeconds: 30,
    }),
  );

  // Rotate this bounded window behind ids that have not been checked yet.
  for (const runId of ids) {
    if (pending.delete(runId)) pending.add(runId);
  }

  for (const item of batch.completed) {
    pending.delete(item.runId);
    if (item.status !== "done") {
      const detail = [item.error, item.schemaError, item.result].find(
        (value) => typeof value === "string" && value.trim(),
      );
      throw new Error(detail ?? `${item.runId}: ${item.status}`);
    }
    completed.push(item); // Process each result as soon as it finishes.
  }

  for (const failure of batch.errors ?? []) {
    pending.delete(failure.runId);
    throw new Error(`${failure.runId}: ${failure.error}`);
  }
}

return completed;

Each agents_wait call accepts 1–1000 run ids. It returns:

type AgentsWaitResult = {
  completed: Array<{
    runId: string;
    status: "done" | "failed" | "killed" | "timeout";
    result: string;
    structured?: unknown;
    error?: string;
    schemaError?: string;
    sessionKey: string;
    label?: string;
    usage?: { inputTokens: number; outputTokens: number };
  }>;
  pending: string[];
  errors?: Array<{
    runId: string;
    error: "not_found" | "not_owner";
  }>;
};

A completed item can contain partial structured data and still have status: "failed" when the provider or runtime fails afterward. In that case, error is the authoritative terminal failure. Recovery code should prefer a nonblank error, then schemaError, then a nonblank result, and finally a run/status fallback.

Individual failed items do not make a mixed agents_wait poll a top-level tool error. The poll remains a successful JSON result so callers can process its completed, pending, and errors arrays independently.

The call returns immediately when any requested child is already complete, when at least one pending child completes, when no valid pending ids remain, or when its timeout expires. Completed records are idempotent, so passing an already-completed run id returns its result again. Only the spawning session or its authorized parent chain can wait on a collector.

This is bounded long polling, not a busy status loop. Keep passing only the remaining run ids until pending is empty. Collector mode supports native OpenClaw sub-agents; it does not support ACP runtime, thread binding, visible sessions, or persistent session mode.

Limits and roadmap

Swarm v1 runs one-shot collector children; the planned agents.session() API will add stateful multi-turn workers. Children currently run on the local Gateway’s sub-agent lane; cloud placement is planned as an explicit spawn option. Saved workflow definitions and a graph DSL are not part of Swarm’s current direction.

Related

• Code Mode for the QuickJS guest runtime and activation rules
• Sub-agents for child policy, isolation, and session behavior
• Multi-agent sandbox tools for per-agent restrictions
• Tools overview for tool profiles and policy routing