API Reference

Quick reference of all exported functions, types, and classes per package.

`@workkit/types`

Export	Kind	Description
`Result<T,E>`	type	Discriminated union: `{ ok: true, value: T }` or `{ ok: false, error: E }`
`AsyncResult<T,E>`	type	`Promise<Result<T,E>>`
`Ok(value)`	function	Create a success Result
`Err(error)`	function	Create an error Result
`isOk(result)`	function	Type guard for success
`isErr(result)`	function	Type guard for error
`unwrap(result)`	function	Extract value or throw
`Branded<T, Brand>`	type	Nominal typing helper
`brand(value, tag)`	function	Brand a value
`kvKey(value)`	function	Brand as KVKey
`d1RowId(value)`	function	Brand as D1RowId
`r2ObjectKey(value)`	function	Brand as R2ObjectKey
`durableObjectId(value)`	function	Brand as DurableObjectId
`queueMessageId(value)`	function	Brand as QueueMessageId
`TypedKVNamespace<T>`	type	Typed KV binding augmentation
`TypedD1Result<T>`	type	Typed D1 query result
`TypedR2Object`	type	Typed R2 object
`TypedQueue<T>`	type	Typed queue binding
`TypedMessageBatch<T>`	type	Typed message batch
`TypedDurableObjectStorage`	type	Typed DO storage
`JsonValue`, `JsonObject`, `JsonArray`	types	JSON-safe types
`DeepPartial<T>`, `DeepReadonly<T>`	types	Recursive utility types
`WorkerFetchHandler`	type	`fetch()` handler signature
`WorkerScheduledHandler`	type	`scheduled()` handler signature
`WorkerQueueHandler`	type	`queue()` handler signature
`WorkerModule`	type	Full worker module export
`ExecutionContext`	type	Worker execution context
`ScheduledEvent`	type	Cron trigger event
`MaybePromise<T>`	type	`T
`Prettify<T>`	type	Flatten intersection types
`assertNever(x)`	function	Exhaustive switch helper

`@workkit/errors`

Export	Kind	Description
`WorkkitError`	abstract class	Base error with code, statusCode, retryable, retryStrategy
`NotFoundError`	class	404, not retryable
`ConflictError`	class	409, retryable (exponential)
`ValidationError`	class	400, not retryable, carries `issues[]`
`UnauthorizedError`	class	401, not retryable
`ForbiddenError`	class	403, not retryable
`TimeoutError`	class	504, retryable (exponential)
`RateLimitError`	class	429, retryable (fixed)
`ServiceUnavailableError`	class	503, retryable (exponential)
`BindingError`	class	500, not retryable
`BindingNotFoundError`	class	500, not retryable
`InternalError`	class	500, not retryable
`ConfigError`	class	500, not retryable
`RetryStrategies`	object	Factory for retry strategies: `.none()`, `.immediate()`, `.fixed()`, `.exponential()`
`getRetryDelay(strategy, attempt)`	function	Calculate delay for attempt, returns `number
`isRetryable(error)`	function	Type guard: is error retryable?
`getRetryStrategy(error)`	function	Extract retry strategy from any error
`errorToResponse(error)`	function	Convert WorkkitError to HTTP Response
`fromHttpStatus(status, msg?)`	function	Create WorkkitError from HTTP status code
`isWorkkitError(error)`	function	Type guard for WorkkitError
`isErrorCode(error, code)`	function	Type guard for specific error code
`serializeError(error)`	function	Serialize any error to structured JSON
`wrapError(error, msg?)`	function	Wrap unknown error as WorkkitError

`@workkit/env`

Export	Kind	Description
`parseEnv(rawEnv, schema)`	async function	Validate env (async validators)
`parseEnvSync(rawEnv, schema)`	function	Validate env (sync only, throws on async)
`createEnvParser(schema)`	function	Create reusable parser with `.parse()` and `.parseSync()`
`EnvValidationError`	class	Error with `.issues: EnvIssue[]`
`isStandardSchema(value)`	function	Type guard for Standard Schema objects
`detectPlatform()`	function	Returns `‘workerd'
`resolveEnv()`	function	Get env from current platform
`EnvSchema`	type	`Record<string, StandardSchemaV1>`
`InferEnv<T>`	type	Infer output types from schema
`InferRawEnv<T>`	type	Infer input types from schema

`@workkit/env/validators`

Export	Kind	Description
`d1()`	function	D1Database binding validator
`kv()`	function	KVNamespace binding validator
`r2()`	function	R2Bucket binding validator
`queue()`	function	Queue binding validator
`ai()`	function	AI binding validator
`durableObject()`	function	DurableObjectNamespace binding validator
`service()`	function	Service binding validator

`@workkit/d1`

Export	Kind	Description
`d1(binding, options?)`	function	Create typed D1 client
`D1Error`	class	Base D1 error
`D1QueryError`	class	SQL query error
`D1ConstraintError`	class	Constraint violation (409)
`D1BatchError`	class	Batch operation error
`D1MigrationError`	class	Migration error
`classifyD1Error(error, sql?, params?)`	function	Classify raw D1 errors
`snakeToCamel(column)`	function	Column name transformer
`migrate(db, migrations, options?)`	function	Run pending migrations
`migrationStatus(db, migrations, options?)`	function	Check migration status

TypedD1 Client Methods

Method	Returns	Description
`.first<T>(sql, params?)`	`Promise<T \| null>`	Single row query
`.all<T>(sql, params?)`	`Promise<T[]>`	Multi-row query
`.run(sql, params?)`	`Promise<D1RunResult>`	Mutation (INSERT/UPDATE/DELETE)
`.exec(sql)`	`Promise<D1ExecResult>`	Raw SQL execution
`.prepare<T>(sql, params?)`	`TypedPreparedStatement<T>`	Create prepared statement
`.batch(statements)`	`Promise<D1BatchResult[]>`	Atomic batch execution
`.select<T>(table)`	`SelectBuilder<T>`	Fluent SELECT builder
`.insert(table)`	`InsertBuilder`	Fluent INSERT builder
`.update(table)`	`UpdateBuilder`	Fluent UPDATE builder
`.delete(table)`	`DeleteBuilder`	Fluent DELETE builder
`.raw`	`D1Database`	Underlying binding

`@workkit/kv`

Export	Kind	Description
`kv<T>(binding, options?)`	function	Create typed KV client
`validateKey(key)`	function	Validate KV key
`prefixKey(prefix, key)`	function	Prepend prefix to key
`stripPrefix(prefix, key)`	function	Remove prefix from key
`wrapKVError(error, context)`	function	Wrap KV errors with context
`assertKVBinding(binding)`	function	Assert binding exists
`assertValidTtl(ttl)`	function	Assert TTL >= 60

WorkkitKV Client Methods

Method	Returns	Description
`.get(key, options?)`	`Promise<T \| null>`	Get value
`.getWithMetadata<M>(key, options?)`	`Promise<{value, metadata, cacheStatus}>`	Get with metadata
`.put(key, value, options?)`	`Promise<void>`	Store value
`.delete(key)`	`Promise<void>`	Delete key
`.getMany(keys, options?)`	`Promise<Map<string, T>>`	Batch get
`.putMany(entries, options?)`	`Promise<void>`	Batch put
`.deleteMany(keys)`	`Promise<void>`	Batch delete
`.list<M>(options?)`	`AsyncIterable<KVListEntry<M>>`	List keys (auto-paginate)
`.listKeys(options?)`	`Promise<KVListEntry[]>`	Collect all keys
`.has(key)`	`Promise<boolean>`	Check key existence
`.raw`	`KVNamespace`	Underlying binding

`@workkit/auth`

Export	Kind	Description
`signJWT(payload, options)`	async function	Sign a JWT token
`verifyJWT(token, options)`	async function	Verify and decode JWT
`decodeJWT(token)`	function	Decode JWT without verification
`parseDuration(str)`	function	Parse ‘1h’, ‘30m’, ‘7d’ to seconds
`hashPassword(password, options?)`	async function	PBKDF2 password hashing
`verifyPassword(password, stored)`	async function	Constant-time password verification
`createSessionManager(config)`	function	KV-backed session manager
`createAuthHandler(config)`	function	Auth middleware factory
`extractBearerToken(request)`	function	Extract Bearer token from header
`extractBasicAuth(request)`	function	Extract Basic auth credentials

`@workkit/ratelimit`

Export	Kind	Description
`fixedWindow(options)`	function	Fixed window rate limiter
`slidingWindow(options)`	function	Sliding window rate limiter
`tokenBucket(options)`	function	Token bucket rate limiter
`composite(limiters)`	function	Combine multiple limiters
`parseDuration(str)`	function	Parse duration to milliseconds
`rateLimitHeaders(result)`	function	Generate X-RateLimit-* headers
`rateLimitResponse(result, msg?)`	function	Generate 429 Response

`@workkit/ai`

Export	Kind	Description
`ai(binding)`	function	Create typed AI client
`streamAI(binding, model, input, options?)`	async function	Stream text generation
`fallback(binding, models, inputs, options?)`	async function	Try models in order
`withRetry(fn, options?)`	async function	Retry wrapper
`estimateTokens(text)`	function	Approximate token count

`@workkit/ai-gateway`

Export	Kind	Description
`createGateway(config)`	function	Multi-provider AI gateway
`createRouter(config)`	function	Model-to-provider router
`createCostTracker(config)`	function	Token usage and cost tracker
`withCache(gateway, config)`	function	Cache wrapper for gateway
`withLogging(gateway, config)`	function	Logging wrapper for gateway

`@workkit/queue`

Export	Kind	Description
`queue<T>(binding)`	function	Create typed queue producer
`createConsumer<T>(options)`	function	Per-message consumer handler
`createBatchConsumer<T>(options)`	function	Batch consumer handler
`createDLQProcessor<T>(options)`	function	Dead letter queue processor
`RetryAction`	enum	`ACK`, `RETRY`, `DEAD_LETTER`

`@workkit/cron`

Export	Kind	Description
`createCronHandler(options)`	function	Route scheduled events to tasks
`matchCron(schedule, cron)`	function	Check if cron matches
`parseCron(expression)`	function	Parse cron expression
`describeCron(expression)`	function	Human-readable description
`nextRun(expression)`	function	Next scheduled Date
`isValidCron(expression)`	function	Validate cron expression
`withTimeout(ms)`	function	Timeout middleware
`withRetry(maxRetries, options?)`	function	Retry middleware
`withErrorReporting(getQueue, reporter?)`	function	Error reporting middleware
`withLock(getKV, key, options, handler)`	function	Distributed lock wrapper
`acquireLock(kv, key, options?)`	function	Acquire a KV-based lock

`@workkit/do`

Export	Kind	Description
`typedStorage<T>(raw)`	function	Type-safe DO storage wrapper
`createStateMachine(config)`	function	Finite state machine for DOs
`scheduleAlarm(storage, schedule)`	async function	Schedule a DO alarm
`createAlarmHandler(config)`	function	Route alarms to named handlers
`parseDuration(str)`	function	Parse duration to milliseconds
`createDOClient<T>(namespace, id)`	function	Typed RPC client for DO stubs
`singleton(namespace, name)`	function	Get named DO instance

`@workkit/logger`

Export	Kind	Description
`createLogger(options?)`	function	Create a standalone structured logger
`logger(options?)`	function	Hono middleware for structured request logging
`getLogger(c)`	function	Get a logger from Hono context with request context
`getRequestContext()`	function	Get current request context from AsyncLocalStorage
`LogLevel`	type	`"debug" \| "info" \| "warn" \| "error"`
`LogFields`	type	`Record<string, unknown>`
`LogEntry`	type	Structured log entry with level, msg, ts, and fields
`Logger`	type	Logger interface with `.debug()`, `.info()`, `.warn()`, `.error()`, `.child()`
`CreateLoggerOptions`	type	Options for `createLogger`
`LoggerMiddlewareOptions`	type	Options for `logger` middleware
`RequestContext`	type	Request context: requestId, method, path, startTime, fields

`@workkit/testing`

Export	Kind	Description
`createTestEnv(config)`	function	One-call typed env factory
`createMockKV()`	function	In-memory KVNamespace mock
`createMockD1()`	function	In-memory D1Database mock
`createFailingD1()`	function	Always-failing D1 mock
`createMockR2()`	function	In-memory R2Bucket mock
`createMockQueue()`	function	In-memory Queue mock
`createMockDO()`	function	In-memory DO storage mock
`createRequest(path, options?)`	function	Request factory
`createExecutionContext()`	function	Mock ExecutionContext

`@workkit/r2`

Export	Kind	Description
`r2(bucket, options?)`	function	Typed R2 client wrapper
`createPresignedUrl(bucket, options)`	function	Generate presigned PUT/GET URLs
`multipartUpload(bucket, key, options?)`	function	Start a multipart upload session
`streamToBuffer(stream)` / `streamToText(stream)` / `streamToJson<T>(stream)`	function	Body stream helpers
`fromS3Key(key)` / `toS3Key(key)`	function	S3 ↔ R2 key migration helpers
`validateR2Key(key)` / `assertR2Binding(b)` / `wrapR2Error(err, ctx)`	function	Defensive helpers

`@workkit/cache`

Export	Kind	Description
`cache(kv, options?)`	function	Typed KV-backed cache client
`swr(kv, key, fetcher, options?)`	function	Stale-while-revalidate read-through
`cacheAside(kv, options?)`	function	Cache-aside pattern helper
`taggedCache(kv, options?)`	function	Tagged invalidation client
`createMemoryCache(options?)`	function	In-process LRU cache
`buildCacheUrl(key)`	function	Compose cache key URL

`@workkit/crypto`

Export	Kind	Description
`encrypt(key, data)` / `decrypt(key, ciphertext)`	function	AES-256-GCM encrypt / decrypt
`encryptWithAAD(key, data, aad)` / `decryptWithAAD(key, ciphertext, aad)`	function	AES-GCM with additional authenticated data
`generateKey()` / `exportKey(key)` / `importKey(base64)`	function	AES-256-GCM key lifecycle
`deriveKey(source, context)`	function	PBKDF2 (string) or HKDF (CryptoKey) key derivation
`envelope.seal / open / rotate`	object	Envelope encryption (DEK + master key)
`hash(algo, data)`	function	SHA-1 / SHA-256 / SHA-384 / SHA-512
`hmac(secret, data)` / `hmac.verify(secret, data, mac)`	function	HMAC sign + constant-time verify
`generateSigningKeyPair(algo?)`	function	Ed25519 (default) or ECDSA keypair
`exportSigningKey(key)` / `importSigningKey(base64, type, algo?)`	function	Public/private signing key serialization
`sign(privateKey, data)` / `sign.verify(publicKey, data, signature)`	function	Detached signature + verify
`randomBytes(n)` / `randomHex(n)` / `randomUUID()`	function	Crypto-secure random

`@workkit/api`

Export	Kind	Description
`api(config)`	function	Define a typed API surface
`createRouter(config)`	function	Build a router from API definitions
`generateOpenAPI(api)`	function	Build OpenAPI 3.1 spec from definitions
`parsePath` / `matchPath` / `buildPath` / `toOpenAPIPath` / `parseQuery`	function	Path utilities
`validate` / `validateSync` / `tryValidate` / `isStandardSchema`	function	Standard Schema validation helpers
`createLlmsRoutes` / `generateLlmsTxt` / `generateLlmsFullTxt`	function	`llms.txt` generation

`@workkit/health`

Export	Kind	Description
`createHealthCheck(probes, options?)`	function	Compose probes into a `HealthChecker`
`healthHandler(probes, options?)`	function	Hono-style `/health` handler
`kvProbe(kv)` / `d1Probe(db)` / `r2Probe(bucket)` / `doProbe(ns)` / `aiProbe(ai)` / `queueProbe(q)`	function	Built-in binding probes

`@workkit/turnstile`

Export	Kind	Description
`verifyTurnstile(token, secret, options?)`	function	Server-side CAPTCHA verification
`turnstile(options)`	function	Hono middleware that gates handlers on a valid token

`@workkit/features`

Export	Kind	Description
`createFlags(kv, options?)`	function	KV-backed feature flag client
`evaluate(flag, context)`	function	Evaluate a flag against a user context (rollout %, targeting)

`@workkit/mail`

Export	Kind	Description
`mail(binding, options?)`	function	Typed email send client over `SendEmail` binding
`parseEmail(raw)`	function	Parse Email Routing inbound message
`createEmailHandler(opts)`	function	Build an inbound email handler
`createEmailRouter(routes)`	function	Route inbound emails to handlers
`composeMessage(opts)`	function	Compose a `MailMessage` from address/subject/body parts
`validateAddress(addr)` / `isValidAddress(addr)`	function	Address validation helpers
`MailError` / `InvalidAddressError` / `DeliveryError`	class	Domain errors

`@workkit/chat`

Export	Kind	Description
`createChatTransport(env, options?)`	function	WebSocket transport factory
`ChatSessionDO`	DO class	Re-exportable Durable Object for chat sessions
`ChatMessage`	type	Discriminated union of typed chat events

`@workkit/notify`

Export	Kind	Description
`define(spec, options)`	function	Define a typed notification with channel rendering
`createNotifyConsumer(adapters)`	function	Queue consumer that dispatches via adapters
`ALL_MIGRATIONS`	const	D1 schema for core (preferences, opt-out, records)

Subpath imports: @workkit/notify/email, @workkit/notify/inapp, @workkit/notify/whatsapp — each ships an *_MIGRATION_SQL plus an *Adapter factory.

`@workkit/browser`

Export	Kind	Description
`browser(binding, options?)`	function	Acquire a Browser Rendering session
`withPage(session, fn, options?)`	function	Run `fn(page)` with guaranteed cleanup
`loadFonts(page, fonts, options?)`	function	Inject `@font-face` declarations safely

`@workkit/pdf`

Export	Kind	Description
`renderPdf(session, html, options?)`	function	Render HTML to PDF with header/footer presets
`storePdf(bucket, key, bytes, options?)`	function	Store rendered PDF in R2
`presignPdf(bucket, key, options)`	function	Generate a presigned download URL
`presets`	object	Page-size and margin presets
`raw(html)`	function	Mark a string as already-escaped HTML

`@workkit/agent`

Export	Kind	Description
`tool(spec)`	function	Define a Standard-Schema-validated tool
`defineAgent(spec)`	function	Compose a multi-turn agent loop
`handoff(target, options?)`	function	Synthetic tool that hands off to another agent
`AgentEvent`	type	Discriminated union streamed by `agent.stream()`
`HandoffCycleError` / `BudgetExceededError`	error class	Domain-specific failures

`@workkit/memory`

Export	Kind	Description
`createMemory(options)`	function	Memory factory (D1 + optional Vectorize/AI/KV)
`getSchema()`	function	D1 schema SQL for migrations
`cosineSimilarity` / `estimateTokens` / `extractSearchTerms`	function	Recall scoring utilities
`Memory` / `Conversation` / `Fact` / `RecallResult` / `MemoryError`	type	Public types

`@workkit/mcp`

Export	Kind	Description
`createMCPServer(config)`	function	MCP server with tools, resources, prompts
`generateOpenAPISpec(server)`	function	Export OpenAPI from a server instance
`validateInput(schema, input)`	function	Standard Schema validation helper
`ToolAnnotations`	type	MCP 2025-06 tool safety hints

`@workkit/workflow`

Export	Kind	Description
`createDurableWorkflow(name, config)`	function	Builder for DO-backed workflows
`createWorkflow(name, config)`	function	Alias for non-durable testing flows
`WorkflowExecutionDO`	DO class	Re-exportable Durable Object for execution state
`parseDuration(str)`	function	Parse `"30s"`, `"5m"`, `"1h"` to ms
`generateExecutionId()`	function	Create a unique execution ID

`@workkit/approval`

Export	Kind	Description
`createApprovalGate(config)`	function	Approval gate factory
`ApprovalRequestDO`	DO class	Re-exportable Durable Object for live requests
`evaluatePolicies(action, policies)`	function	Match an action against registered policies
`generateApprovalToken` / `verifyApprovalToken` / `generateApprovalKeys`	function	Ed25519 signed approval tokens
`createAuditProjection(db)`	function	Append-only audit projection over D1

`@workkit/cli`

The workkit CLI is published as a single binary. Run via bunx workkit <cmd>.

Command	Description
`init`	Scaffold a new Workers project with workkit defaults
`add [packages...]`	Interactively add `@workkit/*` packages to an existing project
`catalog`	List every workkit package with one-line descriptions
`check`	Run the constitution check on the current repo
`gen-client`	Generate a typed client from an `@workkit/api` definition
`gen-docs`	Generate API reference markdown from `src/index.ts` exports
`migrate`	Apply D1 migrations from a directory
`seed`	Seed a D1 database from a JSON or SQL fixture