ADR 0582 clause 3 writes the key holder "with the why, the ask and the time": LeaseHolder gains ask and at,
which LeaseHandedAway ignores (it reads handed-to alone). The grants part's user-list key gains lease-handed,
so the bus node's engine follows the grants part's list alone once the lease is handed (ADR 0571 clause 8)
and never falls back to the controller's; a key written before reads false.
Tests: a row in the lease table of TestTheCopiedComposerComposesAsTheControllers; the old key (shaped as
EncodeGrantsUserList writes it today) and the flag's round trip added to the existing user-list case in
delivery_test.go; no new test function.
(issue 774, 774/S3)
Claude-Session: https://claude.ai/code/session_01NcbgfJ9Gum47zkFKWRaovL
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