Two assertions that fire if the embedded shim registry drifts out
of sync with the pen-mcp catalog:
1. Every add_*_v0 name pen-mcp exposes must have a shim —
catches "added a pen-mcp tool, forgot the builder / shim /
Nitro SERVER_BUILDERS update" triple-edit drift.
2. Every shim key must exist in pen-mcp — catches stale shims
for removed or renamed tools.
Failure message names exactly which tools are missing on each
side so the fix is a copy-paste, not a search. Pairs with the
existing short-circuit test — together they lock the invariant
that elements.md catalog = shim set = Nitro registry.
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