JavaScript Runtime

This is a reference for the JavaScript runtime contract. It is the surface a JavaScript orchestrator script runs against: the values the host binds at script start, and the helpers a script calls to record progress, dispatch child work, attach artifacts, and finish.

Example script

Every call below is a published symbol from the package contract, in the order an author would chain them.

phase("draft");
log("checkpoint", { step: 1 });
workflow.checkpoint({ label: "draft", state: { step: 1 } });
await agent.run({
  prompt: "Summarize findings",
  label: "summarize",
  preset: "operator",
});
workflow.artifact({ kind: "log", label: "step", content: { step: 1 } });
workflow.final({ ok: true, result: { count: 1 } });

Runtime Inventory

Scan the published JavaScript symbols and shared schemas below. Filter by symbol path, schema id, description, or lifecycle when those facets are present. Open a card for available metadata and shared-schema links, and copy its stable anchor when you need a deep link.

21 published JavaScript runtime items from the package contract.

Filter JavaScript runtime items

Symbol or schema

Lifecycle

Visibility

Symbols

args

#javascript.args

Mutable invocation argument value bound from workflow request args JSON at script start. The binding is a non-null object snapshot; property reads and writes affect only the in-script view and do not change the original request payload.

Lifecycle: ActiveVisibility: Public

Kind: ValueMutability: Mutable objectNullability: Non-nullBinding lifecycle: Snapshot at bind

Symbol path: args
Symbol id: javascript.args

Examples

{ "subject": "release", "count": 2, "prefix": "echo" }

log

#javascript.log

Synchronously emits one workflow-scoped log record. The first argument must be a non-empty string message; an optional second argument supplies JSON-compatible structured fields.

Lifecycle: ActiveVisibility: Public

Kind: Function

Symbol path: log
Symbol id: javascript.log

Shared schemas

javascript.schema.json_compatible#/sharedSchemas/javascript.schema.json_compatible/schema

Examples

log("checkpoint", { step: 1 })

agent

#javascript.agent

Root agent namespace for the installed agent.run child-dispatch helper.

Lifecycle: ActiveVisibility: Public

Kind: NamespaceMutability: Fixed bindingNullability: Non-nullBinding lifecycle: Live namespace

Symbol path: agent
Symbol id: javascript.agent

Examples

agent.run({ prompt: "Summarize findings", label: "summarize" })

agent.run

#javascript.agent.run

Dispatches one child agent run from a closed spec object with a required prompt and optional model or preset fields. Returns a promise that resolves to the child result object after policy checks and child_dispatch emission.

Lifecycle: ActiveVisibility: Public

Kind: Method

Symbol path: agent.run
Symbol id: javascript.agent.run

Shared schemas

javascript.schema.agent_run_spec#/sharedSchemas/javascript.schema.agent_run_spec/schema

Examples

await agent.run({ prompt: "Summarize findings", label: "summarize", preset: "operator" })

parallel

#javascript.parallel

Runs an array of agent run specs or item functions concurrently and returns a promise that resolves to an array of child results. Each function item is invoked with undefined this.

Lifecycle: ActiveVisibility: Public

Kind: Function

Symbol path: parallel
Symbol id: javascript.parallel

Examples

await parallel([{ prompt: "first" }, { prompt: "second", label: "two" }])

pipeline

#javascript.pipeline

Maps each items entry through a required worker function and optional next stage callback, running stages sequentially per item. Returns a promise that resolves to a pipeline result array.

Lifecycle: ActiveVisibility: Public

Kind: Function

Symbol path: pipeline
Symbol id: javascript.pipeline

Examples

await pipeline([1, 2], (item) => item * 2, (prior, item) => prior + item)

phase

#javascript.phase

Synchronously records one named workflow phase transition for progress tracking. The name must be a non-empty string.

Lifecycle: ActiveVisibility: Public

Kind: Function

Symbol path: phase
Symbol id: javascript.phase

Examples

phase("draft")

workflow

#javascript.workflow

Root workflow namespace for installed checkpoint, artifact, budget, final, log, and resumeState helpers.

Lifecycle: ActiveVisibility: Public

Kind: NamespaceMutability: Fixed bindingNullability: Non-nullBinding lifecycle: Live namespace

Symbol path: workflow
Symbol id: javascript.workflow

Examples

workflow.artifact({ kind: "log", label: "step" })

workflow.artifact

#javascript.workflow.artifact

Registers one workflow artifact with kind and label metadata. Optional content must be JSON-compatible and is subject to maxArtifactBytes policy.

Lifecycle: ActiveVisibility: Public

Kind: Method

Symbol path: workflow.artifact
Symbol id: javascript.workflow.artifact

Shared schemas

javascript.schema.artifact_spec#/sharedSchemas/javascript.schema.artifact_spec/schema

Examples

workflow.artifact({ kind: "log", label: "step", content: { step: 1 } })

workflow.budget

#javascript.workflow.budget

Returns the current workflow budget counters and emits one budget record. The helper does not accept arguments.

Lifecycle: ActiveVisibility: Public

Kind: Method

Symbol path: workflow.budget
Symbol id: javascript.workflow.budget

Shared schemas

javascript.schema.budget_snapshot#/sharedSchemas/javascript.schema.budget_snapshot/schema

Examples

workflow.budget()

workflow.checkpoint

#javascript.workflow.checkpoint

Persists one labeled checkpoint with optional JSON-compatible state for later resume through workflow.resumeState().

Lifecycle: ActiveVisibility: Public

Kind: Method

Symbol path: workflow.checkpoint
Symbol id: javascript.workflow.checkpoint

Shared schemas

javascript.schema.checkpoint_spec#/sharedSchemas/javascript.schema.checkpoint_spec/schema

Examples

workflow.checkpoint({ label: "draft", state: { step: 1 } })

workflow.final

#javascript.workflow.final

Terminates the workflow with an optional final value. When both workflow.final and a returned value are present, workflow.final wins for terminal result selection.

Lifecycle: ActiveVisibility: Public

Kind: Method

Symbol path: workflow.final
Symbol id: javascript.workflow.final

Examples

workflow.final({ ok: true, result: { count: 1 } })

workflow.log

#javascript.workflow.log

Synchronously emits one workflow-scoped log record. The first argument must be a string message; an optional second argument supplies JSON-compatible structured fields.

Lifecycle: ActiveVisibility: Public

Kind: Method

Symbol path: workflow.log
Symbol id: javascript.workflow.log

Shared schemas

javascript.schema.json_compatible#/sharedSchemas/javascript.schema.json_compatible/schema

Examples

workflow.log("checkpoint", { step: 1 })

workflow.resumeState

#javascript.workflow.resume-state

Reads checkpoint state restored for a resumed workflow session, or undefined when no resume state is bound.

Lifecycle: ActiveVisibility: Public

Kind: Method

Symbol path: workflow.resumeState
Symbol id: javascript.workflow.resume-state

Shared schemas

javascript.schema.checkpoint_spec#/sharedSchemas/javascript.schema.checkpoint_spec/schema

Examples

workflow.resumeState()

Shared schemas

Checkpoint specification object

#javascript.schema.checkpoint_spec

Closed object shape for workflow.checkpoint spec arguments.

Visibility: Public

Schema

Required: label

Closed object shape for workflow.checkpoint spec arguments.

Properties

labelstringRequired
state#/sharedSchemas/javascript.schema.json_compatible/schemaOptional

Examples

{ "label": "draft", "state": {} }

Artifact specification object

#javascript.schema.artifact_spec

Closed object shape for workflow.artifact spec arguments.

Visibility: Public

Schema

Required: kind, label

Closed object shape for workflow.artifact spec arguments.

Properties

kindstringRequired
labelstringRequired
content#/sharedSchemas/javascript.schema.json_compatible/schemaOptional
visibilitystringOptional

Examples

{ "kind": "log", "label": "step" }

Workflow budget snapshot object

#javascript.schema.budget_snapshot

Closed object shape returned by workflow.budget.

Visibility: Public

Schema

Required: maxAgents, concurrency

Closed object shape returned by workflow.budget.

Properties

maxAgentsnumberRequired
concurrencynumberRequired
sandboxModestringOptional
maxRunDurationMsnumberOptional
maxWorkerDurationMsnumberOptional
maxOutputBytesPerWorkernumberOptional
maxArtifactBytesnumberOptional
maxTokensnumberOptional

Examples

{ "maxAgents": 4, "concurrency": 2 }

JSON-compatible serializable value

#javascript.schema.json_compatible

Closed union of JSON-compatible serializable values accepted by installed runtime helpers.

Visibility: Public

Schema

Composition: oneOf (6)

Closed union of JSON-compatible serializable values accepted by installed runtime helpers.

Examples

{ "step": 1 }

"note"

null

Agent run specification object

#javascript.schema.agent_run_spec

Closed object shape for agent.run spec arguments.

Visibility: Public

Schema

Required: prompt

Closed object shape for agent.run spec arguments.

Properties

promptstringRequired
labelstringOptional
presetstringOptional
modelProviderstringOptional
modelstringOptional
reasoningEffortstringOptional

Examples

{ "prompt": "Summarize findings", "label": "summarize" }

String-keyed invocation record

#javascript.schema.string_key_record

Closed top-level object for args and meta value bindings exposed at workflow bind time.

Visibility: Public

Schema

Closed top-level object for args and meta value bindings exposed at workflow bind time.

Examples

{ "topic": "release" }

JavaScript Runtime

Example script

Runtime Inventory

Symbols

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Shared schemas

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