Addresses review round 5 on #2099 (three suppressed comments, no posted ones).
The `fetch: createProxyFetch()` line in each Node client is the whole of that
client's proxy support — it is what puts the proxy at the BOTTOM of the fetch
stack, where InspectorClient's wrappers compose over it rather than discarding
it. `InspectorClient` sets `fetchFn` unconditionally, so the transport-level
fallback never fires for these clients. Both lines could have been deleted with
every existing test still green.
- CLI: a test that runs a real `tools/list` against a real HTTP test server with
HTTP_PROXY pointed at a real forwarding proxy, asserting the request traversed
it. Behavioral rather than structural on purpose — the defect this replaces was
a runtime dispatch failure no structural assertion would have caught. It clears
all six proxy vars first so an ambient value cannot route it elsewhere.
- TUI: the mock added earlier always returned undefined, so the proxy branch was
never exercised. `createProxyFetch`'s return is now controllable, and two tests
assert the sentinel reaches `environment.fetch` when a proxy is configured and
that the slot stays unset when one is not.
Both were confirmed to fail with their client's wiring line removed.
Also updates the `InspectorClientEnvironment.fetch` doc in core/mcp/types.ts,
which still told callers that Node leaves this undefined and uses the global
fetch.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01JTHVxSu8AUgHRLvo1ntZ8H
Signed-off-by: cliffhall <cliff@futurescale.com>