JavaScript Runtime

Look up every published runtime symbol and shared schema from the installed package JavaScript runtime contract on a stable static docs route.

Symbol metadata glossary

Symbol cards show kind, mutability, nullability, and binding lifecycle as glossary-backed pills when the package contract publishes those fields. The definitions below explain the published meanings — including Value versus function kind — without inventing extra enum values.

Kind: Kind classifies what the published symbol is. A Value is a bound data binding such as args or meta. A function is a callable runtime helper such as log. Namespace and method kinds appear only when the contract publishes those shapes.
Mutability: Mutability describes whether the bound object may change after bind. Mutable object means the binding exposes an object authors can update. Fixed binding means the binding identity stays fixed for the published lifetime.
Nullability: Nullability describes whether the binding may be null. Non-null means the published contract treats the binding as always present when that field is published.
Binding lifecycle: Binding lifecycle describes how the binding relates to the workflow run. Snapshot at bind captures the value when the binding is established. Live namespace stays connected to the live namespace surface for the published lifetime.

How the JavaScript runtime works

At script start the host binds Value symbols such as javascript.args and javascript.meta from the workflow request. The script body then chains published helpers — phase, log, workflow.checkpoint, agent.run, workflow.artifact, and workflow.final — to record progress, dispatch child work, attach artifacts, and terminate. The example below composes only published call patterns from the package contract.

Record a phase
Call phase with a published string label so the host can track progress before heavier work starts.
javascript.phase
Emit a log record
Call log with a message string and an optional JSON-compatible detail object for workflow-scoped logging.
javascript.log
Persist a checkpoint
Call workflow.checkpoint with a closed spec object (label plus optional JSON-compatible state) so a later resume can restore progress.
javascript.workflow.checkpoint
Dispatch a child agent
Await agent.run with a closed spec that includes a required prompt and optional label and preset fields from the published agent-run schema.
javascript.agent.run
Register an artifact
Call workflow.artifact with kind and label metadata, and optional JSON-compatible content, to attach durable output to the run.
javascript.workflow.artifact
Finish the workflow
Call workflow.final with an optional JSON-compatible value to terminate the script and return a final result.
javascript.workflow.final

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: Value Mutability: Mutable object Nullability: Non-null Binding 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: Namespace Mutability: Fixed binding Nullability: Non-null Binding 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: Namespace Mutability: Fixed binding Nullability: Non-null Binding 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

Symbol metadata glossary

How the JavaScript runtime works

Runtime Inventory

Symbols

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Shared schemas

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Shared schemas

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