pub fn validate_enqueue(batch: &[Envelope]) -> Result<(), StoreError>Expand description
The boundary validation every backend’s enqueue runs before it writes anything —
ONE function so the rule cannot drift between four adapters, and the layer is the
store because the API and the harnesses call Store::enqueue directly, never through
the runtime. Batch-level: a repeated id WITHIN one batch is an IdConflict on every
backend rather than a constraint error from whichever row the database reached first.