Review finding, valid — the previous SDK fix covered only the
non-default branch: in the default mode under Code Mode the wire filter
dropped exit_plan_mode but the registry-rendered tools:sdk section
still advertised its binding, offering default-mode agents a call that
can only error and breaking the byte-identical claim (a no-dsh-mode
deployment's registry never saw the tool, so its SDK never listed it).
The SDK re-render extracts to one helper both branches share: the
non-default branch passes the mode's visibility rule, the default
branch hides exactly the exit binding. The pinning test now compares
the default-mode SDK byte-for-byte against a bare deployment without
dsh-mode — the strongest form of the invariant the RFC states.