_run_idempotent() (chat completions / responses) keyed the shared
_idem_cache purely on the client-supplied Idempotency-Key header plus a
body fingerprint, with no profile identity anywhere in the key. Under
gateway.multiplex_profiles, both the native routes and their /p/<profile>/
mirrors share the same process-global cache, so two different profiles'
clients sending the same Idempotency-Key with a matching fingerprint (a
realistic case for automation/SDKs that derive the key deterministically
from request content) silently share a cached response instead of each
profile running its own turn.
The sibling /v1/runs admission API already scopes its own idempotency
namespace this way (_run_idempotency_scope() folds in
_api_request_profile.get() or "default"); this mirrors that exact
expression into _run_idempotent()'s cache key.
2b7eb97fbf