WASM runtime

The WASM runtime is the full Meerkat agent stack compiled to wasm32 for browser deployment. It routes through the same AgentFactory::build_agent() pipeline as all other surfaces.

This page is intentionally browser/WASM-specific rather than a cross-surface tabbed page. Use Examples: Mobpack first if you want the packaging/deployment path that usually leads into browser delivery.

Build the WASM bundle

CLI
Manual (wasm-pack)

Assemble a self-contained, runnable web bundle from a .mobpack artifact. The command does not compile wasm32; it copies the required prebuilt meerkat-web-runtime from the generated wasm-pack --target web output directory named by --wasm:

rkat mob web build ./dist/my-mob.mobpack -o ./dist/web-bundle --wasm ./meerkat-web-runtime/pkg --trust-policy permissive

Then serve and open it: python3 -m http.server -d ./dist/web-bundle.

Build the WASM package directly with wasm-pack:

RUSTFLAGS='--cfg getrandom_backend="wasm_js"' \
  wasm-pack build meerkat-web-runtime --target web --out-dir pkg

Initialize runtime

Use init-time credentials and provider base URLs to seed the browser runtime’s realm config. The @rkat/web RuntimeConfig is provider-specific: anthropicApiKey, openaiApiKey, geminiApiKey, and the matching provider base URL fields (anthropicBaseUrl, openaiBaseUrl, geminiBaseUrl). The old generic apiKey/baseUrl compatibility fields are deleted, and SessionConfig does not accept per-session apiKey or baseUrl.

import { MeerkatRuntime } from "@rkat/web";
import * as wasm from "@rkat/web/wasm/meerkat_web_runtime.js";

const runtime = await MeerkatRuntime.initFromMobpack(wasm, mobpackBytes, {
  anthropicApiKey: "sk-ant-...",
  model: "claude-sonnet-4-6",
});

For proxy deployments, pass a provider-specific dummy key and base URL. The proxy injects the real server-side credential.

const runtime = await MeerkatRuntime.init(wasm, {
  anthropicApiKey: "proxy",
  anthropicBaseUrl: "http://localhost:3100/anthropic",
  model: "claude-sonnet-4-6",
});

Create session and run turn

const session = runtime.createSession({
  model: "claude-sonnet-4-6",
});

const result = await session.turn("Hello");
console.log(result.text);

For OAuth or host-owned cloud credentials, register an external auth resolver and bind the session to a structural auth binding. The selected realm binding must be configured to use the WASM external-resolver credential source.

import { registerExternalAuthResolver, withAuthBinding } from "@rkat/web";

registerExternalAuthResolver(wasm, async (authBinding) => {
  const token = await hostAuth.freshAccessToken(authBinding);
  return {
    kind: "inline_secret",
    secret: token.accessToken,
    metadata: { account_id: token.accountId },
    expires_at: token.expiresAt,
  };
});

const bound = runtime.createSession(withAuthBinding(
  { realm: "team-alpha", binding: "anthropic" },
  { model: "claude-sonnet-4-6" },
));

Poll events

for (const event of session.pollEvents()) {
  if (event.type === "text_delta") {
    document.body.innerText += event.delta;
  }
}

Mob lifecycle in browser

// Create mob from definition
const mob = await runtime.createMob({
  id: "research-team",
  orchestrator: { profile: "lead" },
  profiles: {
    lead: { model: "claude-sonnet-4-6" },
    worker: { model: "claude-sonnet-4-6" },
  },
});

// Spawn members
await mob.spawn([
  { profile: "lead", agent_identity: "lead-1" },
  { profile: "worker", agent_identity: "worker-1" },
]);

// Wire peers
await mob.wire("lead-1", "worker-1");

// Inspect runtime state
const members = await mob.listMembers();
const leadStatus = await mob.memberStatus("lead-1");

const sub = await mob.subscribeMemberEvents("lead-1");

for (const event of sub.poll()) {
  console.log(event.type, event);
}

sub.close();

Cross-mob comms

Wire ambassadors across mobs for inter-faction communication. mob.wire() accepts either a local member name or an external peer target, so trust between members of different mobs is established by wiring each ambassador to the other side’s peer identity (comms name, address, Ed25519 public key).

// Wire an ambassador to a peer in another mob
await northMob.wire("ambassador-north", {
  external: {
    name: "ambassador-south",
    address: southAddress,
    identity: { kind: "ed25519_public_key", public_key: southPublicKey },
  },
});

// Send work to a member through the canonical member path
await northMob
  .member("ambassador-north")
  .send("Send a message to the south faction proposing an alliance on the eastern front.");

Direct comms_send and comms_peers are reserved low-level placeholders rather than current wasm-bindgen exports or public @rkat/web wrapper methods. Inter-agent messaging happens through member-directed turn submission and the comms tools available to agents during their turns (send_message, send_request, send_response, and peers).

What is available on wasm32

Category	Available	Not available
Agent loop	Full agent state machine, streaming, budget	—
Providers	Anthropic, OpenAI, Gemini (browser fetch)	—
Sessions	Ephemeral sessions	Persistent sessions (filesystem)
Mobs	Full orchestration, flows, lifecycle	—
Comms	In-process (`inproc`) transport	TCP, UDS, network transports
Tools	Custom tools, tool dispatch	Shell tools, filesystem tools
Skills	Embedded skills, HTTP skills	Filesystem skill sources
Hooks	In-process hooks	Command hooks, filesystem hooks
Compaction	Context compaction	—
Other	—	MCP client, delegated work orchestration

Next step

Examples: Mobpack — the packaging/deployment path that often comes before browser delivery
Examples: Mobs — the multi-agent runtime model behind many WASM demos

Getting started

Concepts

Guides: Models And Hosting

Guides: Runtime Behavior

Guides: Orchestration

Examples: Foundations

Examples: Capabilities

Examples: Orchestration And Deployment

Build the WASM bundle

Initialize runtime

Create session and run turn

Poll events

Mob lifecycle in browser

Cross-mob comms

What is available on wasm32

Next step

​Build the WASM bundle

​Initialize runtime

​Create session and run turn

​Poll events

​Mob lifecycle in browser

​Subscribe to member events

​Cross-mob comms

​What is available on wasm32

​Next step

Build the WASM bundle

Initialize runtime

Create session and run turn

Poll events

Mob lifecycle in browser

Subscribe to member events

Cross-mob comms

What is available on wasm32

Next step