Fix critical regression: restore dict return for reload preflight

The previous commit (2cf6608) introduced a critical regression by returning
MCPResponse instead of dict when Unity is reloading. This broke the reload
retry loop because _is_reloading_response() only handles dict responses and
immediately returns False for non-dict types, causing the retry helper to
exit instead of waiting through domain reloads.

Changes:
- Revert reload preflight return from MCPResponse to dict format
- Restore return type annotation to dict[str, Any] (remove | MCPResponse)
- Preserve all reload detection fields: success, state, retry_after_ms, error
- Applied to both Server/ and MCPForUnity/ versions

The dict return format ensures _is_reloading_response() correctly detects
reload state via resp.get("state") == "reloading" check, maintaining the
polite retry loop behavior during Unity domain reloads.

Addresses CodeRabbit critical feedback:
- #360 (review)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Author: sakurachan

MCPForUnity/UnityMcpServer~/src/unity_connection.py

@@ -225,7 +225,7 @@ def receive_full_response(self, sock, buffer_size=config.buffer_size) -> bytes:
             logger.error(f"Error during receive: {str(e)}")
             raise
 
-    def send_command(self, command_type: str, params: dict[str, Any] | None = None) -> dict[str, Any] | MCPResponse:
+    def send_command(self, command_type: str, params: dict[str, Any] | None = None) -> dict[str, Any]:
         """Send a command with retry/backoff and port rediscovery. Pings only when requested."""
         # Defensive guard: catch empty/placeholder invocations early
         if not command_type:
@@ -276,12 +276,12 @@ def read_status_file(target_hash: str | None = None) -> dict | None:
         try:
             status = read_status_file(target_hash)
             if status and (status.get('reloading') or status.get('reason') == 'reloading'):
-                return MCPResponse(
-                    success=False,
-                    error="Unity domain reload in progress, please try again shortly",
-                    data={"state": "reloading", "retry_after_ms": int(
-                        config.reload_retry_ms)}
-                )
+                return {
+                    "success": False,
+                    "state": "reloading",
+                    "retry_after_ms": int(config.reload_retry_ms),
+                    "error": "Unity domain reload in progress, please try again shortly",
+                }
         except Exception:
             pass
 

Server/unity_connection.py

@@ -225,7 +225,7 @@ def receive_full_response(self, sock, buffer_size=config.buffer_size) -> bytes:
             logger.error(f"Error during receive: {str(e)}")
             raise
 
-    def send_command(self, command_type: str, params: dict[str, Any] | None = None) -> dict[str, Any] | MCPResponse:
+    def send_command(self, command_type: str, params: dict[str, Any] | None = None) -> dict[str, Any]:
         """Send a command with retry/backoff and port rediscovery. Pings only when requested."""
         # Defensive guard: catch empty/placeholder invocations early
         if not command_type:
@@ -276,12 +276,12 @@ def read_status_file(target_hash: str | None = None) -> dict | None:
         try:
             status = read_status_file(target_hash)
             if status and (status.get('reloading') or status.get('reason') == 'reloading'):
-                return MCPResponse(
-                    success=False,
-                    error="Unity domain reload in progress, please try again shortly",
-                    data={"state": "reloading", "retry_after_ms": int(
-                        config.reload_retry_ms)}
-                )
+                return {
+                    "success": False,
+                    "state": "reloading",
+                    "retry_after_ms": int(config.reload_retry_ms),
+                    "error": "Unity domain reload in progress, please try again shortly",
+                }
         except Exception:
             pass