fix: issue 1138 windows encoding (#1139)

* fix(windows): use utf-8 for text file operations

* fix(windows): normalize sandbox path masking

* fix(windows): preserve utf-8 handling after backend split

backend/app/gateway/routers/artifacts.py

@@ -63,7 +63,7 @@ def _extract_file_from_skill_archive(zip_path: Path, internal_path: str) -> byte
     summary="Get Artifact File",
     description="Retrieve an artifact file generated by the AI agent. Supports text, HTML, and binary files.",
 )
-async def get_artifact(thread_id: str, path: str, request: Request) -> FileResponse:
+async def get_artifact(thread_id: str, path: str, request: Request) -> Response:
     """Get an artifact file by its path.
 
     The endpoint automatically detects file types and returns appropriate content types.
@@ -147,12 +147,12 @@ async def get_artifact(thread_id: str, path: str, request: Request) -> FileRespo
         return FileResponse(path=actual_path, filename=actual_path.name, media_type=mime_type, headers={"Content-Disposition": f"attachment; filename*=UTF-8''{encoded_filename}"})
 
     if mime_type and mime_type == "text/html":
-        return HTMLResponse(content=actual_path.read_text())
+        return HTMLResponse(content=actual_path.read_text(encoding="utf-8"))
 
     if mime_type and mime_type.startswith("text/"):
-        return PlainTextResponse(content=actual_path.read_text(), media_type=mime_type)
+        return PlainTextResponse(content=actual_path.read_text(encoding="utf-8"), media_type=mime_type)
 
     if is_text_file_by_content(actual_path):
-        return PlainTextResponse(content=actual_path.read_text(), media_type=mime_type)
+        return PlainTextResponse(content=actual_path.read_text(encoding="utf-8"), media_type=mime_type)
 
     return Response(content=actual_path.read_bytes(), media_type=mime_type, headers={"Content-Disposition": f"inline; filename*=UTF-8''{encoded_filename}"})

backend/app/gateway/routers/mcp.py

@@ -152,7 +152,7 @@ async def update_mcp_configuration(request: McpConfigUpdateRequest) -> McpConfig
         }
 
         # Write the configuration to file
-        with open(config_path, "w") as f:
+        with open(config_path, "w", encoding="utf-8") as f:
             json.dump(config_data, f, indent=2)
 
         logger.info(f"MCP configuration updated and saved to: {config_path}")

backend/app/gateway/routers/skills.py

@@ -307,7 +307,7 @@ async def update_skill(skill_name: str, request: SkillUpdateRequest) -> SkillRes
         }
 
         # Write the configuration to file
-        with open(config_path, "w") as f:
+        with open(config_path, "w", encoding="utf-8") as f:
             json.dump(config_data, f, indent=2)
 
         logger.info(f"Skills configuration updated and saved to: {config_path}")