Interface: ParallelBranchOptions

Defined in: src/core-flow/Parallel.ts:128

Options bag accepted by ParallelBuilder.branch() for per-method overrides. Backwards-compatible with the legacy .branch(id, runner, name?) signature: when the third arg is a string it's still treated as name.

Properties

groupTranslator?

readonly optional groupTranslator?: GroupTranslator<unknown>

Defined in: src/core-flow/Parallel.ts:132

Per-method translator override. See BranchEntry.groupTranslator.

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name?

readonly optional name?: string

Defined in: src/core-flow/Parallel.ts:130

Human-friendly name for this branch. Default: the branch id.

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required?

readonly optional required?: boolean

Defined in: src/core-flow/Parallel.ts:170

Mark this branch as REQUIRED: its failure rejects the whole Parallel run — even under a tolerant .mergeOutcomesWithFn() merge — with an error that names the branch. Default false (existing semantics: strict merges aggregate failures at the join; tolerant merges receive them as BranchOutcome entries).

Fail-fast wiring: when EVERY branch is required, footprintjs's fork-level failFast is engaged (Promise.all) so the first failure aborts the fan-out immediately — siblings are not awaited and the Merge stage never runs. When only SOME branches are required, the fan-out stays best-effort (Promise.allSettled) and required failures are enforced at the Merge join instead — footprintjs's failFast is all-or-nothing per fork node, so engaging it for a mixed set would wrongly abort the run when an OPTIONAL sibling throws. See docs/guides/concepts.md (Parallel).

Pause semantics under fail-fast: with every branch required, a branch that PAUSES (pauseHere()) pre-empts its siblings the same way a failure does — Promise.all settles on the first non-success, so still-running siblings are not awaited before the run surfaces the RunnerPauseOutcome. The checkpoint reflects the paused branch; resume() continues from there and re-attributes any post-resume required-branch failure just like run() does. Under the default best-effort fork, a pause is only surfaced after every sibling settles.

Nested-mounting limitation: required-branch attribution and the synthetic composition.exit are wired through Parallel.run() / Parallel.resume(). When the Parallel's chart is instead MOUNTED into an outer composition (e.g. Sequence.step('s', parallel)), the outer runner's executor runs the chart — the fork-level failFast still aborts the fan-out, but the rejection surfaces RAW (no required branch 'x' failed wrapping) and the nested Parallel's composition.enter is left without a matching exit. See README Decision 8.