Sequence
Class: Sequence
Defined in: src/core-flow/Sequence.ts:97
Every primitive (LLMCall, Agent), every composition (Sequence, Parallel, Conditional, Loop), and every pattern factory result implements Runner. That makes them freely nestable: any runner can be a child of any composition.
Extends
Constructors
Constructor
new Sequence(
opts,steps):Sequence
Defined in: src/core-flow/Sequence.ts:109
Parameters
opts
steps
readonly StepEntry[]
Returns
Sequence
Overrides
Properties
enable
readonlyenable:EnableNamespace
Defined in: src/core/RunnerBase.ts:484
Enable-namespace for high-level observability features. Each method
attaches a pre-built CombinedRecorder and returns an unsubscribe
function. Consumers write ONE line to enable rich observability,
instead of N .on() subscriptions.
Inherited from
id
readonlyid:string
Defined in: src/core-flow/Sequence.ts:99
name
readonlyname:string
Defined in: src/core-flow/Sequence.ts:98
Methods
attach()
attach(
recorder):Unsubscribe
Defined in: src/core/RunnerBase.ts:474
Attach a footprintjs CombinedRecorder to observe every subsequent run.
LIFECYCLE CONTRACT (who owns cleanup):
- Attached recorders live for the RUNNER's lifetime, not a run's.
NOTHING auto-expires per-run — a recorder attached once observes
every later
run()until you call the returned Unsubscribe. - The CALLER owns cleanup. Keep the Unsubscribe and call it when the observer's life ends (request scope, UI unmount, test teardown).
- Event listeners (
on()/once()) follow the same rule, with two extra outs: pass{ signal }for AbortSignal auto-cleanup, or callremoveAllListeners()to bulk-drop listeners (listeners ONLY — recorders are not affected). once()listeners are the only self-expiring subscription.
attach() is NOT idempotent: every call pushes another entry. (At run time footprintjs's executor dedupes recorders by ID, so same-ID duplicates won't double-fire — but the runner-side array still grows.) Attaching in a per-run loop without detaching is the classic server leak; attach once, or detach per-run.
Parameters
recorder
Returns
Inherited from
create()
staticcreate(opts?):SequenceBuilder
Defined in: src/core-flow/Sequence.ts:122
Parameters
opts?
SequenceOptions = {}
Returns
emit()
emit(
name,payload):void
Defined in: src/core/RunnerBase.ts:522
Emit a consumer-defined custom event.
If name matches a registered event type, this routes exactly like a
library-emitted event (via the typed EventMap). Otherwise it flows
through to wildcard listeners ('*') as an opaque CustomEvent with
minimal meta. Library events remain reserved under agentfootprint.*.
Parameters
name
string
payload
Record<string, unknown>
Returns
void
Inherited from
getLastSnapshot()
getLastSnapshot():
RuntimeSnapshot|undefined
Defined in: src/core/RunnerBase.ts:108
Returns the footprintjs snapshot from the most recent run (or undefined if no run has completed). The snapshot is the CANONICAL STRUCTURE: nodes, edges, executionTree, runtimeStageId, commitLog.
Domain consumers (Lens, Trace, dashboards) read this for shape
and join their own per-stage payload by runtimeStageId. They
MUST NOT re-derive structure from typed events — that's the
design footprintjs's CLAUDE.md Convention 1 explicitly forbids.
Returns undefined before the first run() completes. After,
always returns the snapshot of the most recent run (including
across multi-turn reuse of the same runner instance).
Returns
RuntimeSnapshot | undefined
Inherited from
getSnapshot()
getSnapshot():
RuntimeSnapshot|undefined
Defined in: src/core/RunnerBase.ts:123
Alias for getLastSnapshot() that mirrors FlowChartExecutor.getSnapshot()
so consumers (lens, playground, ExplainableShell) can read the live or
just-completed snapshot through the same method name they'd use on a
footprintjs executor — without having to know whether they're holding
an agentfootprint Runner or a raw executor.
During an active run, returns the live snapshot (commit log + execution tree built incrementally as stages execute). Between runs, returns the last completed run's snapshot. Undefined before any run has started.
Returns
RuntimeSnapshot | undefined
Inherited from
getSpec()
getSpec():
FlowChart
Defined in: src/core/RunnerBase.ts:144
Return the footprintjs FlowChart for this runner — the canonical
design-time blueprint. STABLE REFERENCE across calls (getSpec() === getSpec()). Set once at construction via initChart().
Pairs with the run-time getters (getLastSnapshot,
getCommitCount) and matches ExplainableShell.spec +
specToReactFlow(spec, ...) consumer conventions.
DO NOT OVERRIDE in subclasses — the reference-identity contract
(Lens / OpenAPI / MCP caches memo on this returning the same
object) depends on the inherited body returning this.chart
directly. To customise build behaviour, override buildChart()
instead; this getter must remain a thin cache-read.
Returns
FlowChart
Inherited from
getUIGroup()
getUIGroup<
T>():T|undefined
Defined in: src/core/RunnerBase.ts:180
Return the consumer-shaped UI group for this composition — produced
by invoking the consumer's groupTranslator (if attached) with this
runner's GroupMetadata. Returns undefined when no translator was
attached.
STABLE REFERENCE across calls. Computed on first access and cached;
subsequent calls return the same value. Pairs with getSpec() —
library shape on one side, consumer-shaped UI on the other.
Subclasses MUST override buildUIGroupMetadata() (the next hook) to
supply the GroupMetadata for their composition kind. This method
(the public surface) is final-by-convention — do not override.
Type Parameters
T
T = unknown
Returns
T | undefined
Inherited from
getUIGroupWith()
getUIGroupWith<
T>(override):T|undefined
Defined in: src/core/RunnerBase.ts:224
Translate this runner's group metadata with a CALLER-SUPPLIED
translator that overrides the runner's own default. Used by
parent compositions to apply per-method translator overrides.
See the Runner.getUIGroupWith JSDoc for the contract.
Type Parameters
T
T = unknown
Parameters
override
GroupTranslator<unknown>
Returns
T | undefined
Inherited from
listenerCount()
listenerCount(
type?):number
Defined in: src/core/RunnerBase.ts:447
Diagnostic — how many event listeners this runner currently retains.
No argument = total across all buckets (the leak-detection number);
with a subscription key = that bucket only. Delegates to
EventDispatcher.listenerCount().
Parameters
type?
keyof AgentfootprintEventMap | WildcardSubscription
Returns
number
Inherited from
off()
Call Signature
off<
K>(type,listener):void
Defined in: src/core/RunnerBase.ts:390
Unsubscribe a previously-registered listener.
Type Parameters
K
K extends keyof AgentfootprintEventMap
Parameters
type
K
listener
Returns
void
Inherited from
Call Signature
off(
type,listener):void
Defined in: src/core/RunnerBase.ts:391
Parameters
type
listener
Returns
void
Inherited from
on()
Call Signature
on<
K>(type,listener,options?):Unsubscribe
Defined in: src/core/RunnerBase.ts:367
Subscribe a typed listener. Returns unsubscribe.
Lifecycle: the subscription lives until you call the returned
Unsubscribe, the { signal } you passed aborts, or
removeAllListeners() runs. Nothing auto-expires per-run — pass a
per-run AbortSignal for request-scoped listeners on long-lived
runners (servers).
Type Parameters
K
K extends keyof AgentfootprintEventMap
Parameters
type
K
listener
options?
Returns
Inherited from
Call Signature
on(
type,listener,options?):Unsubscribe
Defined in: src/core/RunnerBase.ts:372
Subscribe to a domain wildcard (e.g. 'agentfootprint.context.') or ''.
Parameters
type
listener
options?
Returns
Inherited from
once()
Call Signature
once<
K>(type,listener,options?):Unsubscribe
Defined in: src/core/RunnerBase.ts:401
Subscribe a one-shot listener (fires once then auto-removes). Accepts { signal }.
Type Parameters
K
K extends keyof AgentfootprintEventMap
Parameters
type
K
listener
options?
Omit<ListenOptions, "once">
Returns
Inherited from
Call Signature
once(
type,listener,options?):Unsubscribe
Defined in: src/core/RunnerBase.ts:406
Parameters
type
listener
options?
Omit<ListenOptions, "once">
Returns
Inherited from
removeAllListeners()
removeAllListeners():
void
Defined in: src/core/RunnerBase.ts:437
Lifecycle escape hatch — drop EVERY event listener on this runner in
one call (typed, domain-wildcard, and '*'). Delegates to
EventDispatcher.removeAllListeners().
For long-lived runners on servers: when you can't thread an
AbortSignal or keep every Unsubscribe handle, call this between
requests to guarantee zero residual subscriptions. Note it also
removes listeners wired by enable.* strategies — re-enable after
calling if you still want them. Does NOT touch attached recorders
(see attach() — recorders have their own Unsubscribe).
Returns
void
Inherited from
resume()
resume(
checkpoint,input?,options?):Promise<string|RunnerPauseOutcome>
Defined in: src/core-flow/Sequence.ts:167
Resume a paused run from its checkpoint. Default behavior: rebuild the
chart, wire the same core recorders + consumer recorders, call
executor.resume(checkpoint, input), and emit pause.resume before
returning. Subclass overrides only if it needs specialized behavior.
Parameters
checkpoint
FlowchartCheckpoint
input?
unknown
options?
RunOptions
Returns
Promise<string | RunnerPauseOutcome>
Overrides
run()
run(
input,options?):Promise<string|RunnerPauseOutcome>
Defined in: src/core-flow/Sequence.ts:154
Execute the runner. Subclass may override for specialized input mapping, but default invokes getSpec() + FlowChartExecutor.
Parameters
input
options?
RunOptions
Returns
Promise<string | RunnerPauseOutcome>