vercel__workflow/.changeset/parallel-inline-optimistic-start.md

workflow, @workflow/core

workflow	@workflow/core
minor	minor

Inline execution now runs up to WORKFLOW_MAX_INLINE_STEPS (default 3) steps in parallel per suspension, each lazily created. An opt-in WORKFLOW_OPTIMISTIC_INLINE_START (default off) additionally starts step bodies before step_started is confirmed, reconciling the in-flight start before the terminal write so a lost create-claim is discarded; it is off by default because under contention a step body can run more than once (e.g. two runs writing to the workflow stream can corrupt it), so only enable it for idempotent steps.