Runtime options

createFlowState({ ... }) is the process-level config. It registers flows, builds the model resolver, opens store profiles, and returns a handle you mount as HTTP (and export from fsdev.config.ts for the CLI).

import { createFlowState, inMemoryStores } from "@flow-state-dev/engine";
import chatFlow from "./src/flows/hello-chat/flow";

export const flowstate = createFlowState({
  flows: { chat: chatFlow },
  models: { default: "openai/gpt-5.4-mini" },
  stores: { default: { primary: inMemoryStores() } },
});

The handle builds the router lazily on the first getRouter() / ready() call.

Method / field	What it does
getRouter()	Resolve HTTP handlers. First call opens stores.
getRuntime()	{ registry, stores, runtimeConfig } for workers and scripts. Same instances the router uses.
ready()	Eager warmup. Idempotent.
dispose()	Close workers, then store adapters.
activeProfile	Resolved profile name. Reading it before ready() resolves the profile and throws if FSD_ENV names a missing one.
settings	The settings bag you passed in.
meta	{ flowKeys, profileKeys, declaredSlots, devtool? }.

Narrative: Engine setup, App configuration, Persistence.

createFlowState fields

Field	Type	Default	What it does
flows	Record<string, FlowInstance>	required	Registered flows. Keys are stable ids for the registry.
stores	StoresConfig	required	Named profiles. At least one. See Stores.
models	FlowStateModelsConfig	—	Shorthand model resolver. See Models.
modelResolver	ModelResolver	built from models	Escape hatch. When set, models is ignored. Use for mocks or a fully custom resolver.
defaultProfile	string	first declared profile	Active profile when FSD_ENV is unset. NODE_ENV is not consulted.
settings	object	—	Read in blocks as ctx.settings. Type it by declaration-merging FlowStateSettings. Process-wide and one shape for every flow; for settings that differ between two registered copies of one flow, use config, read as ctx.flow.config.
voice	{ provider? }	—	Runtime voice provider (TTS/STT). Distinct from a flow's voice speak defaults.
onError	(error, { method, path }) => void	—	HTTP-level error sink.
errorCapture	handler	off	Block-aware sink: failing block identity plus flow / request / session / user ids. You write the adapter; the framework ships no vendor SDK.
onBackgroundWork	(promise) => void	—	Keep-alive for work that outlives the response. On Vercel, pass (p) => after(() => p).
detectInterruptedOnStartup	boolean	true	Scan for interrupted requests at boot. Turn off on serverless if the scan contends with the first request.
dispatchDrainTimeoutMs	number	30000	How long dispose() waits for dispatch runs still running in this process. 0 skips the wait and still reports what was left. The default is sized for a serverless shutdown grace period, so raise it past your longest expected run on a long-lived host doing slow background work. It does not cover the worker shutdown that follows: dispose() then closes the worker, and an adapter like BullMQ waits — outside this ceiling — for jobs this process already claimed. Queued work no worker has claimed is not waited on. Size a host's shutdown grace period for both phases, not this value alone.
debugEndpointsEnabled	boolean	false	Privileged debug routes. fsdev dev sets FSDEV_DEBUG_ENDPOINTS=1 on a loopback host.
debugAllowAnonymousLocal	boolean	true when FSDEV_DEBUG_ALLOW_ANONYMOUS_LOCAL is 1, else false	Let debug routes accept requests with no Origin header (curl, scripts, same-origin browser GETs). Off, they get 403. A request whose Origin is not loopback is rejected either way; createFlowState has no origin allowlist (createFlowApiRouter takes one as debugAllowedOrigins). fsdev dev turns it on for a loopback host; fsdev serve does not. Only for a server bound to loopback.
defaultSseHeartbeatMs	number	15000	Router-level SSE ping when a flow does not set request.sseHeartbeatMs.
staleSweepIntervalMs	number	30000	Stale-request sweeper cadence. 0 disables.
staleSweepThresholdMs	number	60000	Heartbeat age after which a running request is stale.
queuedGraceMs	number	600000	How long an unclaimed queued request may sit before a sweep treats it as lost. Must be finite.
publicReentrySources	string[]	built-in caller-addressed sources	Extra inbound source values allowed on retry / continue / resume. webhook, internal and task cannot be added.
maxChildSessionListLimit	number	100	Largest limit the child-session listing route accepts. The listing is all-time history, so it outgrows any fixed page a client would ask for.
durable	boolean	false	Install the default checkpoint provider so actions with durable: true can recover and ctx.suspend(). Needs a persistent store to survive a process restart.
durabilityRetention	retention object	—	Sweeper for expired suspensions, leases, and orphaned checkpoints. Only with durability on.
worker	WorkerAdapter	—	Execution backend (for example bullmqWorker(...)). Mutually exclusive with dispatcher.
dispatcher	FlowDispatcher	in-process	Low-level "where actions run" hook. Prefer worker.
adapters	inbound adapters	—	Custom transports forwarded to the router.
resolvePrincipal	PrincipalResolver	body userId	Host fallback when a flow has no authentication.resolvePrincipal. Per-flow auth always wins.
chat	{ default?: string }	—	fsdev chat target when you omit the flow argument: "<kind>" or "<kind>.<action>". Not the flow's chat subscription map.
devtool	{ userId?, bearerToken? }	—	Only fsdev dev reads this. Identity and bearer token for the loopback DevTool page. Production serve ignores it.

Models

models is a reshaped createModelResolver config.

Field	Type	Default	What it does
default	model id	—	Fallback when an intent/<name> string cannot resolve. Required once you declare any intents.
intents	Record<string, string[]>	—	Named ladders. model: "intent/chat" walks intents.chat and takes the first candidate with a key and an installed SDK.
keys	Record<string, string>	process.env	Explicit API keys.
gateways	gateway map	auto from env	Gateway instances or configs.
providers	provider map	auto from env	Pre-built AI SDK provider instances.
providerPreference	preference	—	Reorder intent candidates by provider.
retryPolicy	RetryPolicy	2 attempts, 1s base	Fallback retry when a candidate fails.

Env overrides (FSDEV_INTENT_*, FSDEV_DEFAULT_MODEL) are listed under Environment. Depth: Models.

Stores

stores is Record<profileName, { primary, blobs?, queue?, scheduler? }>.

Profile resolution, first match wins:

1. process.env.FSD_ENV
2. defaultProfile
3. The first key in the stores object

Slot	What it holds
primary	Required. Sessions, state, items, requests, content, checkpoints, traces, suspensions, leases.
blobs	Reserved. Backs no store today.
queue	Reserved. Backs no store today.
scheduler	Reserved. Backs no store today.

Only primary resolves into the store registry. blobs, queue, and scheduler are forward-compatible slots: the adapter you name must declare the capability (construction throws if it does not), but declaring one configures nothing. Durable job queues come from a worker adapter; schedules are fired by the host scheduler, not by a store — see Scheduled actions.

Built-in adapters:

Factory	Package	Typical use
inMemoryStores()	@flow-state-dev/engine	Tests and throwaway local runs. Nothing survives dispose().
filesystemStores({ rootDir })	@flow-state-dev/engine	Local files under .fsdev/data.
sqliteStores({ filename })	@flow-state-dev/store-sqlite	Single-process durable store.
postgresStores({ connectionString })	@flow-state-dev/store-postgres	Multi-instance production.

inMemoryStores accepts optional cas and traceStore.maxRequests. filesystemStores also accepts developmentOnly and onPersistError. See Persistence.

Workers

worker is an adapter such as bullmqWorker(...) from @flow-state-dev/bullmq. The adapter's mode decides which sides this process runs:

Mode	This process
"colocated" (default)	Enqueue and consume. Local-dev default.
"dispatch-only"	Enqueue only (web process).
"worker-only"	Consume only. Call ready() so the worker starts; you typically do not serve the router.

worker and dispatcher cannot both be set. See Dispatched work and Background jobs with BullMQ.

See also

• Flow options
• Environment
• Error capture
• Host adapters
• Durable execution
• Custom model resolver