Route application and provider-environment harnesses through the shared MCP
connection owner. Join accepted handshakes during shutdown, retain each failed
close for retry, preserve primary and independent cleanup failures, and release
provider files only after their session closes.
Surface BinarySession close Result errors in production and artifact fixture
teardown. Add real SDK and descriptor-boundary regressions for startup races,
concurrent cleanup, mixed failures and recovery. Use a provider-free plist for
descriptor ownership so installed deep engines cannot change the test outcome.
Verify retained hierarchy limits and summary identity through the production artifact-only composition and real MCP SDK, alongside compiled CLI controls. Deep-provider selection is a separate lane.
Co-authored-by: Aliciawque <166712943+Aliciawque@users.noreply.github.com>
morluto