Meerkat TypeScript SDK

TypeScript client for the Meerkat runtime. The SDK is a thin session-first wrapper over the same runtime-backed contracts used by the CLI, REST, JSON-RPC, and MCP surfaces. It communicates with a local rkat-rpc subprocess over JSON-RPC 2.0 (newline-delimited JSON on stdin/stdout).

Current contract version: 0.5.0.

Installation

npm install @rkat/sdk

Prerequisites

• rkat-rpc binary on PATH -- build it from the Meerkat repo with cargo build -p meerkat-rpc, then ensure the resulting rkat-rpc binary is in your $PATH.
• Node.js >= 18 (uses node:child_process, node:readline, node:test).
• API key for at least one LLM provider set in your environment (e.g. ANTHROPIC_API_KEY, OPENAI_API_KEY, or GOOGLE_API_KEY).

tsconfig Requirements

The SDK is published as ESM ("type": "module" in package.json). Your project's tsconfig.json must use Node16 module resolution:

{
  "compilerOptions": {
    "target": "ES2022",
    "module": "Node16",
    "moduleResolution": "Node16",
    "lib": ["ES2022"],
    "strict": true,
    "esModuleInterop": true
  }
}

Quick Start

import { MeerkatClient } from "@rkat/sdk";

const client = new MeerkatClient();

// Connect spawns `rkat-rpc`, performs the initialize handshake,
// and fetches runtime capabilities.
await client.connect();

// Create a session (runs the first turn immediately).
const session = await client.createSession("What is the capital of Sweden?");

console.log(session.text);      // "Stockholm..."
console.log(session.id);        // UUID of the new session
console.log(session.usage);     // { inputTokens, outputTokens, ... }

// Multi-turn: send a follow-up in the same session.
const followUp = await session.turn("And what is its population?");
console.log(followUp.text);

// Clean up.
await session.archive();
await client.close();

API Reference: MeerkatClient

Constructor

new MeerkatClient(rkatPath?: string)

| Parameter | Type | Default | Description | |-----------|------|---------|-------------| | rkatPath | string | "rkat-rpc" | Path to the RPC binary. |

connect()

async connect(): Promise<this>

Spawns rkat-rpc as a child process, performs the initialize handshake, checks contract version compatibility, and fetches runtime capabilities via capabilities/get. Returns this for chaining.

Throws MeerkatError with code "VERSION_MISMATCH" if the server's contract version is incompatible with the SDK's CONTRACT_VERSION.

close()

async close(): Promise<void>

Kills the rkat-rpc subprocess and cleans up resources.

createSession(prompt, options?)

async createSession(
  prompt: string | ContentBlock[],
  options?: SessionOptions,
): Promise<Session>

Creates a new session and immediately runs the first turn with the given prompt. Returns a runtime-backed Session wrapper whose lastResult tracks the latest RunResult and whose methods (turn, stream, history, archive) stay aligned with canonical backend semantics.

Parameters:

| Parameter | Type | Default | Description | |-----------|------|---------|-------------| | prompt | string \| ContentBlock[] | (required) | The user prompt for the first turn. | | options.model | string | Server default (typically claude-sonnet-4-5) | LLM model name (e.g. "gpt-5.2", "gemini-3-flash-preview", "claude-opus-4-6"). | | options.provider | string | Auto-detected from model | Force a specific provider ("anthropic", "openai", "gemini"). | | options.systemPrompt | string | undefined | Override the default system prompt. | | options.maxTokens | number | undefined | Maximum output tokens for the LLM response. | | options.outputSchema | Record<string, unknown> | undefined | JSON Schema for structured output extraction. | | options.structuredOutputRetries | number | 2 (server default) | Max retries for structured output validation. | | options.hooksOverride | Record<string, unknown> | undefined | Run-scoped hook overrides. | | options.enableBuiltins | boolean | false | Enable built-in tools (task management, etc.). | | options.enableShell | boolean | false | Enable the shell tool (requires enableBuiltins). | | options.enableMemory | boolean | false | Enable semantic memory (memory_search tool + compaction indexing). | | options.enableMob | boolean | false | Enable mob orchestration helpers. | | options.keepAlive | boolean | false | Run in keep-alive mode for inter-agent comms. | | options.commsName | string | undefined | Agent name for comms (required when keepAlive is true). | | options.peerMeta | Record<string, unknown> | undefined | Metadata advertised to peer comms surfaces. | | options.budgetLimits | Record<string, unknown> | undefined | Runtime budget limits for the session. | | options.providerParams | Record<string, unknown> | undefined | Provider-specific parameters (e.g. thinking config). | | options.preloadSkills | string[] | undefined | Skill source UUIDs to load before the run. | | options.skillRefs | SkillRef[] | undefined | Canonical structured skill references. | | options.skillReferences | string[] | undefined | Legacy string skill references; prefer skillRefs. |

createDeferredSession(prompt, options?)

async createDeferredSession(
  prompt: string | ContentBlock[],
  options?: SessionOptions,
): Promise<DeferredSession>

Creates a session identity without running the first turn yet. Use await deferred.startTurn(...) when you want the first runtime-backed turn to happen later.

listSessions()

async listSessions(): Promise<SessionInfo[]>

Returns an array of SessionInfo objects with camelCase fields such as sessionId, sessionRef, messageCount, and isActive.

readSession(sessionId)

async readSession(sessionId: string): Promise<Record<string, unknown>>

Returns the current state payload for a session.

Session lifecycle on wrappers

Cancellation and archive operations live on the runtime-backed session wrappers:

await session.interrupt();
await session.archive();
const history = await session.history({ limit: 20 });

capabilities

client.capabilities

Returns the cached Capability[] collected during connect().

hasCapability(capabilityId)

hasCapability(capabilityId: string): boolean

Returns true if the given capability is "Available" in the runtime. Known capability IDs:

| Capability ID | Description | |---------------|-------------| | "sessions" | Session lifecycle (create/turn/list/read/archive) | | "streaming" | Real-time event streaming | | "structured_output" | JSON schema-based structured output extraction | | "hooks" | Lifecycle hooks | | "builtins" | Built-in tools | | "shell" | Shell tool | | "comms" | Inter-agent communication | | "memory_store" | Semantic memory | | "session_store" | Session persistence | | "session_compaction" | Context compaction | | "skills" | Skill loading and invocation |

requireCapability(capabilityId)

requireCapability(capabilityId: string): void

Throws MeerkatError with code "CAPABILITY_UNAVAILABLE" if the capability is not available.

getConfig()

async getConfig(): Promise<Record<string, unknown>>

Returns the current Meerkat configuration as a JSON object.

setConfig(config)

async setConfig(config: Record<string, unknown>): Promise<void>

Replaces the entire runtime configuration.

patchConfig(patch)

async patchConfig(patch: Record<string, unknown>): Promise<Record<string, unknown>>

Merge-patches the runtime configuration and returns the resulting config.

Public Types

The TypeScript SDK exposes camelCase domain types at the package root. The JSON-RPC snake_case wire format stays internal.

• RunResult is available from session.lastResult, await session.turn(...), await deferred.startTurn(...), and stream.result.
• Usage, SessionInfo, Capability, and SchemaWarning model the runtime responses directly.
• Session and DeferredSession are the canonical runtime-backed wrappers for session lifecycle.
• EventStream yields typed events such as text_delta, turn_completed, and tool_execution_completed.

Use the built-in client helpers directly for capability and skill flows:

const client = new MeerkatClient();
await client.connect();

if (client.hasCapability("skills")) {
  const session = await client.createSession("Review this function");
  const result = await session.invokeSkill(
    { sourceUuid: "source-123", skillName: "code-review" },
    "Focus on performance regressions.",
  );
  console.log(result.text);
}

Error Handling

The SDK provides a hierarchy of error classes, all extending the base MeerkatError:

MeerkatError

class MeerkatError extends Error {
  readonly code: string;
  readonly details?: unknown;
  readonly capabilityHint?: {
    capability_id: string;
    message: string;
  };

  constructor(
    code: string,
    message: string,
    details?: unknown,
    capabilityHint?: { capability_id: string; message: string },
  );
}

Base error class. The code field contains a machine-readable error code (e.g. "VERSION_MISMATCH", "NOT_CONNECTED", "CAPABILITY_UNAVAILABLE"). The optional capabilityHint suggests which capability needs to be enabled.

CapabilityUnavailableError

class CapabilityUnavailableError extends MeerkatError {}

Thrown when a required capability is not available in the runtime (e.g. feature not compiled in, disabled by policy).

SessionNotFoundError

class SessionNotFoundError extends MeerkatError {}

Thrown when a session ID does not exist in the runtime.

SkillNotFoundError

class SkillNotFoundError extends MeerkatError {}

Thrown when a referenced skill cannot be found.

Error handling example

import {
  MeerkatClient,
  MeerkatError,
  CapabilityUnavailableError,
} from "@rkat/sdk";

const client = new MeerkatClient();

try {
  await client.connect();
  const session = await client.createSession("Hello");
  console.log(session.text);
} catch (err) {
  if (err instanceof CapabilityUnavailableError) {
    console.error("Missing capability:", err.message);
    if (err.capabilityHint) {
      console.error("Hint:", err.capabilityHint.message);
    }
  } else if (err instanceof MeerkatError) {
    console.error(`Meerkat error [${err.code}]: ${err.message}`);
  } else {
    throw err;
  }
} finally {
  await client.close();
}

Version Compatibility

The SDK exports CONTRACT_VERSION (currently "0.4.11"). During connect(), the SDK checks that the server's contract version is compatible:

• While the major version is 0, minor versions must match exactly (e.g. SDK 0.1.x requires server 0.1.x).
• Once 1.0.0 is reached, major versions must match (standard semver).

import { CONTRACT_VERSION } from "@rkat/sdk";
console.log(CONTRACT_VERSION);  // "0.4.11"

If the versions are incompatible, connect() throws a MeerkatError with code "VERSION_MISMATCH".

Config Management Example

const client = new MeerkatClient();
await client.connect();

// Read the current config.
const config = await client.getConfig();
console.log(config);

// Replace the entire config.
await client.setConfig({ ...config, max_tokens: 4096 });

// Or merge-patch specific fields.
const updated = await client.patchConfig({ max_tokens: 8192 });
console.log(updated.max_tokens);  // 8192

await client.close();

Structured Output Example

const client = new MeerkatClient();
await client.connect();

const session = await client.createSession("List three European capitals", {
  outputSchema: {
    type: "object",
    properties: {
      capitals: {
        type: "array",
        items: { type: "string" },
      },
    },
    required: ["capitals"],
  },
  structured_output_retries: 3,
});

// Parsed structured output (matches the schema).
console.log(result.structured_output);
// { capitals: ["Paris", "Berlin", "Madrid"] }

// Schema warnings from provider-specific validation issues.
if (result.schema_warnings) {
  for (const w of result.schema_warnings) {
    console.warn(`[${w.provider}] ${w.path}: ${w.message}`);
  }
}

await client.close();

Multi-turn Conversation Example

const client = new MeerkatClient();
await client.connect();

// Create session with first turn.
const session = await client.createSession("My name is Alice.", {
  model: "claude-sonnet-4-5",
});

// Follow-up turns reuse the runtime-backed session handle.
const turn2 = await session.turn("What is my name?");
console.log(turn2.text);  // Should mention "Alice"

// Check session state.
const state = await client.readSession(session.id);
console.log(state);

// List all active sessions.
const sessions = await client.listSessions();
console.log(`Active sessions: ${sessions.length}`);

// Clean up.
await session.archive();
await client.close();

License

MIT OR Apache-2.0