vercel__workflow/.changeset/pre/otel-linked-trace-mode.md

@workflow/core, workflow, @workflow/world-vercel, @workflow/utils

@workflow/core	workflow	@workflow/world-vercel	@workflow/utils
minor	minor	minor	minor

Add WORKFLOW_TRACE_MODE with a new linked default: each workflow/step invocation span is now its own trace root with span links to the delivery and run-origin contexts, instead of one trace spanning the entire run. world-vercel now explicitly injects W3C traceparent/tracestate/baggage headers on outgoing workflow-server requests.

Span names are also friendlier: workflow and step spans now use the short function name (e.g. workflow.execute processOrder, step.execute chargeCard, workflow.start processOrder) instead of the uppercase prefixes and full machine names (WORKFLOW_V2 workflow//./src/jobs/order//processOrder). The full name remains available in the workflow.name / step.name span attributes, and new workflowDisplayName / stepDisplayName helpers are exported from @workflow/utils.

Behavioral changes to telemetry under the new default (set WORKFLOW_TRACE_MODE=continuous to restore the previous trace shape exactly; the span-name change applies in both modes):

• A run no longer shares one trace ID: the trace of the request that called start() no longer contains the workflow's execution spans — navigate via span links or the workflow.run.id attribute instead.
• Sampling decisions are made independently per invocation root (previously one parent-based decision covered the whole run), and the number of root spans/traces increases to one per invocation.
• workflow.execute/step.execute invocation spans (formerly WORKFLOW_V2/STEP) become parentless roots, which changes parent/child-based queries and service-map edges.
• Re-enqueued queue messages forward the original run-origin trace carrier unchanged, rather than each invocation's current context.
• Queries or dashboards matching the old WORKFLOW_V2 .../STEP ... span names must switch to the new names.
• The queue-delivered workflow.execute span kind changed from internal to consumer, matching the queue-delivered step.execute span (this applies in both modes).

Existing attributes and baggage keys are unchanged, and everything remains a no-op when no OpenTelemetry SDK is registered.