The word-based virtual server spans only ~2048^2 names, and plausible
real MCP server names such as file_system or web_search are valid BIP-39
word pairs. When a caller's own server matched the derived one, its tools
stopped passing through and entered alias recovery instead: they were
silently restored to an unrelated proxied tool, or failed the request
with a 500 when no semantic suffix matched.
Record untouched caller MCP tool names as identity entries in the reverse
map, skip those entries when collecting virtual servers and recovery
candidates, and forward them unchanged on an exact hit. Recording is
skipped when nothing was aliased, so an untouched request still keeps an
empty reverse map and a no-op restore path.
Also warn instead of silently forwarding an original name when the alias
space is exhausted, report an empty embedded wordlist, trace the
semantic-suffix fallback because it guesses rather than fails, and build
both alias entry points through one shared constructor so the exhaustion
tests cannot drift away from the production path.
Refs #4916
bdde638c27