DeepSeek Harness Plugin: request-frame-preview (Preview and Download Model Request Frames)

`request-frame-preview` is a DeepSeek Harness plugin designed to help developers inspect and debug the request parameters sent to a model. The plugin provides a “Request Preview” button in the session header, allowing users to view system prompts, tool definitions, and message flow details, and supports downloading the full request frame in JSON format. Data sources include the current running session or historical logs, and it strictly follows the DeepSeek adapter format. As a debugging tool, it exposes read-only HTTP endpoints, but note that its security is intended only for local debugging and should not be relied upon as a security boundary.