Merge origin/main with local pending work and update AGENTS.md references

- Resolve 14 conflicts from popping local stash on top of origin's
  eed1e88 + 8d3352f doc-comment additions (11 mechanical, plus
  version.rs, DashboardAuthenticatorTests.cs, DashboardGalaxyProjector.cs)
- Fix 4 test files that used AGENTS.md as the repo-root sentinel
  (now use CLAUDE.md, since AGENTS.md was removed in 4731ab5)
- Redirect 10 doc citations from AGENTS.md to the matching gateway.md
  sections (Value Model, Status Model, Security, STA Worker Thread
  Model, gRPC Layer rule, cancellation rule)

Verified: solution build clean, x86 worker build clean, 266/266
gateway tests passing, 121/121 worker tests passing.

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

clients/python/src/mxgateway/options.py

@@ -21,6 +21,7 @@ class ClientOptions:
     server_name_override: str | None = None
     call_timeout: float | None = 30.0
     stream_timeout: float | None = None
+    max_grpc_message_bytes: int = 16 * 1024 * 1024
 
     def __post_init__(self) -> None:
         """Validate options; raise `ValueError` for invalid combinations."""
@@ -33,6 +34,8 @@ class ClientOptions:
             raise ValueError("call_timeout must be greater than zero")
         if self.stream_timeout is not None and self.stream_timeout <= 0:
             raise ValueError("stream_timeout must be greater than zero")
+        if self.max_grpc_message_bytes <= 0:
+            raise ValueError("max_grpc_message_bytes must be greater than zero")
 
     def __repr__(self) -> str:
         """Return a repr that redacts the API key value."""
@@ -43,14 +46,18 @@ class ClientOptions:
             f"ca_file={self.ca_file!r}, "
             f"server_name_override={self.server_name_override!r}, "
             f"call_timeout={self.call_timeout!r}, "
-            f"stream_timeout={self.stream_timeout!r})"
+            f"stream_timeout={self.stream_timeout!r}, "
+            f"max_grpc_message_bytes={self.max_grpc_message_bytes!r})"
         )
 
 
 def create_channel(options: ClientOptions) -> grpc.aio.Channel:
     """Create a plaintext or TLS `grpc.aio` channel from client options."""
 
-    channel_options: list[tuple[str, str]] = []
+    channel_options: list[tuple[str, str | int]] = [
+        ("grpc.max_receive_message_length", options.max_grpc_message_bytes),
+        ("grpc.max_send_message_length", options.max_grpc_message_bytes),
+    ]
     if options.server_name_override:
         channel_options.append(("grpc.ssl_target_name_override", options.server_name_override))