TypeScript SDK reference

Public SDK interfaces use camelCase by default. Protocol-bound multimodal content keys (media_type, blob_id, duration_ms) intentionally remain wire-shaped.

Imports

Everything public is re-exported from the package root:

import {
  MeerkatClient,
  Session,
  LiveChannel,
  Mob,
  EventStream,
  EventSubscription,
  MeerkatError,
  CapabilityUnavailableError,
  SessionNotFoundError,
  SkillNotFoundError,
  CONTRACT_VERSION,
} from "@rkat/sdk";

import type {
  RunResult,
  Usage,
  SessionInfo,
  SessionOptions,
  LiveChannelOptions,
  LiveOpenResult,
  LiveStatusResult,
  LiveInputChunkWire,
  ContentBlock,
  Capability,
  SkillKey,
  SkillRef,
  SkillRuntimeDiagnostics,
  SchemaWarning,
  AgentEvent,
  AgentEventEnvelope,
  AttributedMobEvent,
  EventEnvelope,
  AttributedEvent,
  MobMember,
  MobStatus,
  MobSummary,
  SpawnSpec,
  MobFlowStatus,
  MobLifecycleAction,
  MobDefinition,
  TextDeltaEvent,
  TurnCompletedEvent,
  // ... all event types
} from "@rkat/sdk";

Additional client wrappers

The package exports more than the core session lifecycle. The MeerkatClient also exposes:

auth-profile helpers: authProfileList, authProfileGet, authProfileCreate, authProfileDelete
auth-login helpers: authLoginStart, authLoginComplete, authLoginDeviceStart, authLoginDeviceComplete, authLoginProvisionApiKey, authStatusGet, authLogout
realm helpers: realmList, realmGet
typed ingress helper: sendPeerResponseTerminal
MCP live-op helpers: mcpAdd, mcpRemove, mcpReload
blob/skill helpers: getBlob, listSkills
live-channel helpers: liveOpen, liveStatus, liveClose, liveSendInput, liveSendInputImage, liveSendInputVideoFrame, liveCommitInput, liveInterrupt, liveTruncate, liveRefresh, and parseLiveObservation

Core types

RunResult

The result returned by session.turn(), session.invokeSkill(), and deferred.startTurn(). Session creation returns runtime-backed Session or DeferredSession wrappers, and the latest RunResult remains available through session.lastResult or stream.result after an EventStream is fully consumed.

interface RunResult {
  readonly sessionId: string;
  readonly sessionRef?: string;
  readonly text: string;
  readonly turns: number;
  readonly toolCalls: number;
  readonly usage: Usage;
  readonly terminalCauseKind?: TurnTerminalCauseKind;
  readonly structuredOutput?: unknown;
  readonly extractionError?: ExtractionError;
  readonly schemaWarnings?: readonly SchemaWarning[];
  readonly skillDiagnostics?: SkillRuntimeDiagnostics;
}

Field	Type	Description
`sessionId`	`string`	Stable UUID for this session
`sessionRef`	`string \| undefined`	Optional human-readable reference
`text`	`string`	Full assistant text from the last LLM turn
`turns`	`number`	Number of LLM turns in this run
`toolCalls`	`number`	Total tool calls executed in this run
`usage`	`Usage`	Token usage for this run
`terminalCauseKind`	`TurnTerminalCauseKind \| undefined`	Machine-owned terminal cause when success carries a typed terminal condition (e.g. budget exhaustion)
`structuredOutput`	`unknown \| undefined`	Parsed structured output when `outputSchema` was provided
`extractionError`	`ExtractionError \| undefined`	Extraction failure details (`lastOutput`, `attempts`, `reason`) when schema extraction failed after a completed main run
`schemaWarnings`	`SchemaWarning[] \| undefined`	Warnings emitted when structured output didn’t fully match the schema
`skillDiagnostics`	`SkillRuntimeDiagnostics \| undefined`	Runtime diagnostics from the skill subsystem

Session

client.createSession() returns a runtime-backed Session wrapper.

class Session {
  readonly id: string;
  readonly ref?: string;
  readonly text: string;
  readonly usage: Usage;
  readonly turns: number;
  readonly toolCalls: number;
  readonly structuredOutput?: unknown;
  readonly lastResult: RunResult;
}

The Session methods are thin conveniences over canonical runtime calls:

await session.turn(...)
session.stream(...)
await session.history(...)
await session.archive()
await session.interrupt()
await session.invokeSkill(...)
await session.subscribeEvents()

DeferredSession

client.createDeferredSession() reserves session identity now and runs the first turn later through await deferred.startTurn(...).

LiveChannel

LiveChannel is the session-bound helper for the live/* RPC surface. RealtimeChannel was removed with the live-adapter surface; use LiveChannel.session(client, sessionId, options?) instead.

const channel = LiveChannel.session(client, session.id, {
  turningMode: "explicit_commit",
});

const opened: LiveOpenResult = await channel.open();
await channel.sendInputText("hello");
await channel.commitInput("text");
const status: LiveStatusResult = await channel.status();
const refresh = await channel.refresh();
await channel.close();

The helper stores the channel_id returned by live/open. It does not own the WebSocket transport; connect to opened.transport.url with the returned token using the transport appropriate for your app.

Usage

Token usage for a single run. All fields are camelCase — there is no total_tokens field.

interface Usage {
  readonly inputTokens: number;
  readonly outputTokens: number;
  readonly cacheCreationTokens?: number;
  readonly cacheReadTokens?: number;
}

SessionInfo

Summary returned by client.listSessions().

interface SessionInfo {
  readonly sessionId: string;
  readonly sessionRef?: string;
  readonly createdAt: number;
  readonly updatedAt: number;
  readonly messageCount: number;
  readonly totalTokens?: number;
  readonly isActive: boolean;
  readonly model?: string;
  readonly provider?: string;
  readonly lastAssistantText?: string;
  readonly resolvedCapabilities?: ResolvedModelCapabilities;
  readonly labels: Readonly<Record<string, string>>;
}

Capability

A single runtime capability entry, as returned by client.capabilities.

interface Capability {
  readonly id: string;
  readonly description: string;
  readonly status: string;  // "Available", "DisabledByPolicy", "NotCompiled", etc.
}

Status values may be emitted as externally-tagged Rust enum objects (e.g. { DisabledByPolicy: { ... } }). The SDK normalizes these to the key string automatically.

ContentBlock

Content blocks are used in multimodal prompts and tool results. Both createSession() and session.turn() accept string | ContentBlock[] as the prompt parameter.

type ContentBlock =
  | { type: "text"; text: string }
  | { type: "image"; media_type: string; data: string; source?: "inline" }
  | { type: "image"; media_type: string; source: "blob"; blob_id: string }
  | { type: "video"; media_type: string; duration_ms: number; data: string; source?: "inline" }
  | { type: "video"; media_type: string; duration_ms: number; source: "uri"; uri: string };

Variant	Fields	Description
`text`	`text: string`	Plain text content
`image`	`media_type: string`, `data: string`	Base64-encoded image with MIME type (e.g. `"image/png"`)

// Multimodal prompt example
const session = await client.createSession([
  { type: "text", text: "Describe this image" },
  { type: "image", media_type: "image/png", data: base64Data },
]);

SchemaWarning

Emitted when a structured output response did not fully conform to the requested schema.

interface SchemaWarning {
  readonly provider: string;
  readonly path: string;
  readonly message: string;
}

Skill types

SkillKey

Structured skill identifier.

interface SkillKey {
  readonly sourceUuid: string;
  readonly skillName: string;
}

SkillRef

A skill reference is a structured SkillKey.

type SkillRef = SkillKey;

SkillRuntimeDiagnostics

Runtime diagnostics from the skill subsystem. Present on RunResult.skillDiagnostics when the server emits skill health data.

interface SkillRuntimeDiagnostics {
  readonly sourceHealth: SourceHealthSnapshot;
  readonly quarantined: readonly SkillQuarantineDiagnostic[];
}

interface SourceHealthSnapshot {
  readonly state: string;
  readonly invalidRatio: number;
  readonly invalidCount: number;
  readonly totalCount: number;
  readonly failureStreak: number;
  readonly handshakeFailed: boolean;
}

interface SkillQuarantineDiagnostic {
  readonly sourceUuid: string;
  readonly skillId: string;
  readonly location: string;
  readonly errorCode: string;
  readonly errorClass: string;
  readonly message: string;
  readonly firstSeenUnixSecs: number;
  readonly lastSeenUnixSecs: number;
}

EventStream

EventStream is an AsyncIterable<AgentEvent> returned by createSessionStreaming() and session.stream(). It yields typed events as the agent runs, then makes the final RunResult available on stream.result.

class EventStream implements AsyncIterable<AgentEvent> {
  readonly sessionId: string;
  readonly result: RunResult;  // throws if accessed before iteration completes

  [Symbol.asyncIterator](): AsyncGenerator<AgentEvent>;

  /** Consume all events and return the final RunResult. */
  collect(): Promise<RunResult>;

  /** Consume events, accumulate text deltas, return [fullText, result]. */
  collectText(): Promise<[string, RunResult]>;
}

Iterating

for await (const event of session.stream("Summarise this")) {
  if (event.type === "text_delta") {
    process.stdout.write(event.delta);
  }
}
const result = stream.result;

collect()

Discards all events and returns the final result:

const result = await stream.collect();

collectText()

Accumulates all text_delta events and returns the joined string alongside the result:

const [fullText, result] = await stream.collectText();
console.log(fullText);
console.log("Output tokens:", result.usage.outputTokens);

Typed events

All events are discriminated on the type field (snake_case, matching the wire protocol). All other fields are camelCase.

AgentEvent union

type AgentEvent =
  | RunStartedEvent
  | RunCompletedEvent
  | ExtractionSucceededEvent
  | ExtractionFailedEvent
  | RunFailedEvent
  | TurnStartedEvent
  | TextDeltaEvent
  | TextCompleteEvent
  | ToolCallRequestedEvent
  | ToolResultReceivedEvent
  | TurnCompletedEvent
  | ToolExecutionStartedEvent
  | ToolExecutionCompletedEvent
  | ToolExecutionTimedOutEvent
  | CompactionStartedEvent
  | CompactionCompletedEvent
  | CompactionFailedEvent
  | BudgetWarningEvent
  | RetryingEvent
  | HookStartedEvent
  | HookCompletedEvent
  | HookFailedEvent
  | HookDeniedEvent
  | SkillsResolvedEvent
  | SkillResolutionFailedEvent
  | InteractionCompleteEvent
  | InteractionFailedEvent
  | StreamTruncatedEvent
  | ToolConfigChangedEvent
  | BackgroundJobCompletedEvent
  | TranscriptRewriteCommittedEvent
  | MalformedEvent
  | UnknownEvent;

Event parsing fails closed: a type outside the generated KNOWN_AGENT_EVENT_TYPES inventory throws a MeerkatError with code UNKNOWN_EVENT_TYPE. A known type without a parser case in this SDK version is surfaced as UnknownEvent for forward-compatibility, and a known type with a malformed payload is preserved as a MalformedEvent (type: "malformed_event").

Session lifecycle events

interface RunStartedEvent   { type: "run_started";   sessionId: string; prompt: ContentInput }
interface RunCompletedEvent {
  type: "run_completed";
  sessionId: string;
  result: string;
  structuredOutput?: unknown;
  extractionRequired?: boolean;
  usage: Usage;
  terminalCauseKind?: TurnTerminalCauseKind;
}
interface ExtractionSucceededEvent {
  type: "extraction_succeeded";
  sessionId: string;
  structuredOutput: unknown;
  schemaWarnings?: readonly SchemaWarning[];
}
interface ExtractionFailedEvent {
  type: "extraction_failed";
  sessionId: string;
  lastOutput: string;
  attempts: number;
  reason: string;
}
interface RunFailedEvent {
  type: "run_failed";
  sessionId: string;
  errorClass: string;
  error: string;
  terminalCauseKind?: TurnTerminalCauseKind;
  errorReport?: AgentErrorReport | null;
}

Turn and LLM events

interface TurnStartedEvent        { type: "turn_started";         turnNumber: number }
interface TextDeltaEvent          { type: "text_delta";            delta: string }
interface TextCompleteEvent       { type: "text_complete";         content: string }
interface ToolCallRequestedEvent  { type: "tool_call_requested";   id: string; name: string; args: ToolCallArguments }
interface ToolResultReceivedEvent { type: "tool_result_received";  id: string; name: string; content: readonly ContentBlock[]; isError?: boolean }
interface TurnCompletedEvent      { type: "turn_completed";        stopReason?: StopReason; usage: Usage }

type StopReason =
  | "end_turn"
  | "tool_use"
  | "max_tokens"
  | "stop_sequence"
  | "content_filter"
  | "cancelled";

Tool execution events

interface ToolExecutionStartedEvent   { type: "tool_execution_started";    id: string; name: string }
interface ToolExecutionCompletedEvent { type: "tool_execution_completed";   id: string; name: string; content: readonly ContentBlock[]; isError?: boolean; durationMs?: number }
interface ToolExecutionTimedOutEvent  { type: "tool_execution_timed_out";   id: string; name: string; timeoutMs: number }

Compaction events

interface CompactionStartedEvent   { type: "compaction_started";   inputTokens: number; estimatedHistoryTokens: number; messageCount: number }
interface CompactionCompletedEvent { type: "compaction_completed";  summaryTokens: number; messagesBefore: number; messagesAfter: number }
// `reason` mirrors the Rust CompactionFailureReason tagged enum ({ kind, ... }).
interface CompactionFailedEvent    { type: "compaction_failed";     reason: Record<string, unknown> }

Budget events

interface BudgetWarningEvent { type: "budget_warning"; budgetType: BudgetType; used: number; limit: number; percent: number }

type BudgetType = "tokens" | "time" | "tool_calls";

Retry events

interface RetryingEvent { type: "retrying"; attempt: number; maxAttempts: number; error: string; delayMs: number }

Hook events

type HookPoint =
  | "run_started" | "run_completed" | "run_failed"
  | "pre_llm_request" | "post_llm_response"
  | "pre_tool_execution" | "post_tool_execution"
  | "turn_boundary";

interface HookStartedEvent        { type: "hook_started";         hookId: string; point: HookPoint }
interface HookCompletedEvent      { type: "hook_completed";        hookId: string; point: HookPoint; durationMs: number }
interface HookFailedEvent         { type: "hook_failed";           hookId: string; point: HookPoint; error: string }
interface HookDeniedEvent         { type: "hook_denied";           hookId: string; point: HookPoint; reasonCode: string; message: string; payload?: unknown }

Skill events

interface SkillsResolvedEvent       { type: "skills_resolved";         skills: readonly SkillKey[]; injectionBytes: number }
interface SkillResolutionFailedEvent { type: "skill_resolution_failed"; skillKey?: SkillKey; reason?: SkillResolutionFailureReason }

SkillResolutionFailureReason is a typed union discriminated on reasonType (not_found, capability_unavailable, load, parse, source_uuid_collision, source_uuid_mutation_without_lineage, missing_skill_remaps, remap_without_lineage, unknown_skill_alias, remap_cycle, unknown).

Comms events

interface InteractionCompleteEvent { type: "interaction_complete"; interactionId: string; result: string; structuredOutput?: unknown }
interface InteractionFailedEvent   { type: "interaction_failed";   interactionId: string; error: string }

Tool config events

interface ToolConfigChangedEvent { type: "tool_config_changed"; payload: ToolConfigChangedPayload }

// Payload keys intentionally remain wire-shaped (snake_case).
interface ToolConfigChangedPayload {
  operation?: "add" | "remove" | "reload";
  target?: string;
  status_info?: ToolConfigChangeStatus;
  persisted?: boolean;
  applied_at_turn?: number;
}

type ToolConfigChangeStatus =
  | { kind: "boundary_applied"; base_changed: boolean; visible_changed: boolean; revision: number }
  | { kind: "deferred_catalog_delta"; added_hidden_count: number; removed_hidden_count: number; pending_source_count: number }
  | { kind: "warning_failed_closed"; error: string }
  | { kind: "external_tool_delta"; phase: "pending" | "applied" | "draining" | "forced" | "failed"; detail?: string };

Background job events

type BackgroundJobTerminalStatus =
  | "completed"
  | "failed"
  | "aborted"
  | "cancelled"
  | "retired"
  | "terminated";

interface BackgroundJobCompletedEvent {
  type: "background_job_completed";
  jobId: string;
  displayName: string;
  terminalStatus: BackgroundJobTerminalStatus;
  detail: string;
}

terminalStatus is the typed semantic status; detail is the human-readable description.

Stream management

interface StreamTruncatedEvent { type: "stream_truncated"; reason: string }

Transcript rewrite events

interface TranscriptRewriteCommittedEvent {
  type: "transcript_rewrite_committed";
  sessionId: string;
  record: Record<string, unknown>;
}

Type guard utilities

The SDK exports type guards for the most commonly used events:

import {
  isTextDelta,
  isTextComplete,
  isTurnCompleted,
  isToolCallRequested,
  isRunCompleted,
  isRunFailed,
} from "@rkat/sdk";

for await (const event of session.stream("prompt")) {
  if (isTextDelta(event)) {
    process.stdout.write(event.delta);  // TypeScript knows event.delta exists
  }
  if (isTurnCompleted(event)) {
    console.log(event.stopReason, event.usage.inputTokens);
  }
}

Error handling

All errors extend MeerkatError. Catch it as a base class or use the specific subclasses for targeted handling.

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

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

Error classes

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

class CapabilityUnavailableError extends MeerkatError {}
class SessionNotFoundError extends MeerkatError {}
class SkillNotFoundError extends MeerkatError {}

Class	When thrown
`MeerkatError`	Base class for all SDK errors
`CapabilityUnavailableError`	`client.requireCapability()` or `session.invokeSkill()` when the required capability is not available
`SessionNotFoundError`	Server reports that the requested session does not exist
`SkillNotFoundError`	Server reports that a skill reference cannot be resolved

Common error codes

Code	Cause
`NOT_CONNECTED`	Method called before `connect()`
`VERSION_MISMATCH`	Server contract version incompatible with SDK
`CAPABILITY_UNAVAILABLE`	Required capability not enabled in this build
`CLIENT_CLOSED`	Method called after `close()`
`STREAM_NOT_CONSUMED`	`stream.result` accessed before iteration completed
`BINARY_NOT_FOUND`	`rkat-rpc` not found and auto-download failed
`UNKNOWN_EVENT_TYPE`	Streamed event `type` not in the generated known-event inventory

Skills

Both createSession() and session.turn() accept structured skill parameters.

// Preload skills into the system prompt at session creation
const session = await client.createSession("Hello!", {
  preloadSkills: [
    { sourceUuid: "dc256086-0d2f-4f61-a307-320d4148107f", skillName: "extraction-email" },
    { sourceUuid: "dc256086-0d2f-4f61-a307-320d4148107f", skillName: "formatting-markdown" },
  ],
});

// Inject a skill for a specific turn via session.turn()
const result = await session.turn("Extract emails from this text", {
  skillRefs: [{ sourceUuid: "abc123", skillName: "extraction-email" }],
});

// Convenience method on Session — wraps turn() with requireCapability check
const result2 = await session.invokeSkill(
  { sourceUuid: "abc123", skillName: "extraction-email" },
  "Extract emails from this text",
);

Version compatibility

import { CONTRACT_VERSION } from "@rkat/sdk";
console.log(CONTRACT_VERSION);  // "0.7.11"

While the major version is 0, minor versions must match exactly between SDK and server.
From 1.0.0 onwards, standard semver applies: major versions must match.

Version checking happens automatically during connect(). A MeerkatError with code VERSION_MISMATCH is thrown if versions are incompatible.

​Imports

​Additional client wrappers

​Core types

​RunResult

​Session

​DeferredSession

​LiveChannel

​Usage

​SessionInfo

​Capability

​ContentBlock

​SchemaWarning

​Skill types

​SkillKey

​SkillRef

​SkillRuntimeDiagnostics

​EventStream

​Iterating

​collect()

​collectText()

​Typed events

​AgentEvent union

​Session lifecycle events

​Turn and LLM events

​Tool execution events

​Compaction events

​Budget events

​Retry events

​Hook events

​Skill events

​Comms events

​Tool config events

​Background job events

​Stream management

​Transcript rewrite events

​Type guard utilities

​Error handling

​Error classes

​Common error codes

​Skills

​Version compatibility

​See also

Imports

Additional client wrappers

Core types

RunResult

Session

DeferredSession

LiveChannel

Usage

SessionInfo

Capability

ContentBlock

SchemaWarning

Skill types

SkillKey

SkillRef

SkillRuntimeDiagnostics

EventStream

Iterating

collect()

collectText()

Typed events

AgentEvent union

Session lifecycle events

Turn and LLM events

Tool execution events

Compaction events

Budget events

Retry events

Hook events

Skill events

Comms events

Tool config events

Background job events

Stream management

Transcript rewrite events

Type guard utilities

Error handling

Error classes

Common error codes

Skills

Version compatibility

See also