Enforces the same-entity invariant (plan §5.1/§5.3 check 6): every referrer
of a shared filter must resolve to the SAME entity the current save binds it
to. A filter record carries no entity binding of its own — all entity context
lives in the referrers — so cross-entity sharing would let one row's edit
silently break another entity's filter. Unresolvable referrers reject too
(fail closed).
Enforces the same-entity invariant (plan §5.1/§5.3 check 6): every referrer of a shared filter must resolve to the SAME entity the current save binds it to. A filter record carries no entity binding of its own — all entity context lives in the referrers — so cross-entity sharing would let one row's edit silently break another entity's filter. Unresolvable referrers reject too (fail closed).