0d874f91ee
Code-review follow-up on the CLI-40/41/44 branch. ISSUE 1 (all five, critical): the message-only scrub still leaked the server-echoed credential through the redacted error's structured reply accessor (.NET Reply/Statuses, Java reply()/protocolStatus(), Go MxAccessError.Reply via errors.As, Rust reply()/into_reply(), Python raw_reply). The redacted error now carries a scrubbed clone of the reply (protocol_status.message, diagnostic_message, statuses[].diagnostic_text), with per-language tests asserting the reply accessor no longer contains the credential. ISSUE 2 (Rust, critical): ensure_command_success routed MXACCESS_FAILURE to Error::Command (unlike the other four clients), bypassing attach_secrets and leaking via derived Debug/Display. MXACCESS_FAILURE now routes to Error::MxAccess, fixing the cross-client inconsistency. ISSUE 3 (Go, important): the CLI-44 terminal send was unconditionally non-blocking, dropping a genuine terminal error under a full buffer on the never-drop SubscribeEvents path. It is now reserved-slot-non-blocking only for the cancel-on-overflow path and blocking for the never-drop path. New shared fixture authenticate-user.echoed-credential-mxaccess-failure.reply.json wired into all five suites. Minors: whitespace-secret guard on .NET/Java redact helpers; Java preserves exception subtype on redaction; redaction-helper unit tests (Go/Java/.NET). Docs (ClientBehaviorFixtures.md, ClientLibrariesDesign.md) updated to make the structured-field claim true.