Result of a "foundingAdd" send. Deliberately has NO envelope
member:
(a) Per refs/marmot/protocol-core/joining.md lines 21-30 and
refs/marmot/protocol-core/publish-lifecycle.md lines 66-78, the
founding Add has an empty publication obligation, so no transport
envelope exists for it — the absence of this field is the
type-level expression of FOUND-01, not merely an unpublished
envelope.
(b) The caller MUST hand pending straight to confirmPublished()
in the same uninterrupted continuation with no intervening
await (D-01). This invariant is convention, not enforced by
this signature (R-01) — callers must be tested, not trusted.
(c) pending.kind is "commit" (see PendingState's doc
comment), so the existing commit-recording branch of
confirmPublished() applies to it unchanged.
Engine response to MarmotGroupEngine.send.