The validator runs again at launch, before anything is created
A definition can become invalid after it was saved: a node type removed, a workflow written by a path that skipped validation. Re-checking at launch means an invalid workflow fails as a refusal, not as a half-built run.
The rule
Normative: this is the rule
- Launching a workflow re-runs every validation rule against the stored definition.
- On any error the launch is refused before any of its effects exist (no jobs are generated, no pipeline is created, nothing is scheduled and nothing is queued), and the refusal carries the full set of errors.
- Over the API the refusal is
422, with each error reported as acode, amessageand alocator, exactly as the save path reports them.
Rule identifiers are permanent and are never renumbered. Each implementation publishes its own standing against these rules; this specification does not.spec 1.0-draft · VAL-LAUNCH · changed in spec 1.0