Resolve Client.Rust-022..029: MalformedReply, correlation ids, clippy

Client.Rust-022  Restored Error::MalformedReply for register / add_item /
                 add_item2 and the bulk-subscribe / read-bulk / write-bulk
                 dispatch arms so malformed-but-OK replies fail loudly
                 instead of returning Vec::new().
Client.Rust-023  Restored next_correlation_id and routed every CLI close /
                 stream-alarms / acknowledge-alarm / bench-read-bulk call
                 through it so each call carries a unique opaque token.
Client.Rust-024  Added round-trip tests for read_bulk / write_bulk /
                 write2_bulk / write_secured_bulk / write_secured2_bulk
                 plus stream_alarms and percentile_summary unit tests.
Client.Rust-025  RustClientDesign.md re-synced — new bulk SDK, alarms
                 surface, Error variants, CLI command list, and the
                 Windows stack workaround.
Client.Rust-026  Session::read_bulk now borrows a tag slice; bench-read-
                 bulk binds tags once outside the warm-up / steady-state
                 loops.
Client.Rust-027  .cargo/config.toml selector tightened to
                 cfg(all(windows, target_env = "msvc")) and comment
                 rewritten to match reality (release + debug ship the
                 8 MB reservation).
Client.Rust-028  run_batch removed the empty-line break; stdin EOF is
                 the only terminator.
Client.Rust-029  Re-applied Client.Rust-001 / 002 / 012 — added the
                 missing doc comments, renamed BulkReplyKind variants,
                 and replaced the clone-on-copy with a deref under lock
                 so cargo clippy -D warnings is clean.

All resolved at 2026-05-24; cargo fmt + check + clippy + test all green
(55 tests).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

clients/rust/src/error.rs

@@ -106,6 +106,27 @@ pub enum Error {
         /// Detail message from the server.
         message: String,
     },
+
+    /// Gateway returned an `Ok` protocol status but the reply lacked the
+    /// expected typed payload (or carried the wrong payload arm). Distinct
+    /// from [`Error::ProtocolStatus`] because the protocol-level envelope
+    /// itself succeeded — the corruption is in the payload shape.
+    #[error("gateway returned a malformed reply: {detail}")]
+    MalformedReply {
+        /// Human-readable description of what was missing or mismatched.
+        detail: String,
+    },
+
+    /// Server returned `Unavailable` or `ResourceExhausted` — classify
+    /// transient failures separately from the catch-all [`Error::Status`].
+    #[error("gateway unavailable: {message}")]
+    Unavailable {
+        /// Redacted server-supplied detail message.
+        message: String,
+        /// Original `tonic::Status`.
+        #[source]
+        status: Box<tonic::Status>,
+    },
 }
 
 /// Wrapper around an [`MxCommandReply`] whose `protocol_status` reported a
@@ -174,6 +195,10 @@ impl From<tonic::Status> for Error {
                 message,
                 status: Box::new(status),
             },
+            Code::Unavailable | Code::ResourceExhausted => Self::Unavailable {
+                message,
+                status: Box::new(status),
+            },
             _ => Self::Status(Box::new(status)),
         }
     }