Introduction

DeepSeek Harness (DSH) follows the “everything is a plugin” philosophy. Quickly locating context or reviewing historical details in long conversations is a common requirement in agent development. dsh-msgrail is a client-side plugin for this scenario. It provides vertically distributed message-index dots along the right edge of the conversation area, supporting hover previews and click-to-jump.

Purpose

This is a rail plugin that provides message-index functionality and is maintained by futongxu9-maker. It displays the conversation structure using a column of dots on the right edge, and supports hover previews, click-to-jump, and automatic loading of history. It uses a pure-plugin (shell.overlay) architecture, does not modify host code, and allows DSH upgrades without worrying about breakage.

Installation and Activation

Install it using the official plugin command:

dsh plugin --profile web add github:futongxu9-maker/dsh-msgrail

After installation completes, refresh the page; the column of dots will automatically appear on the right edge of the conversation area.

Core Features

The plugin implements the following core capabilities:

  1. Message Index: A vertical column of dots is displayed on the right edge of the conversation. Each real user message corresponds to one dot (context nodes injected by plugins are automatically excluded).
  2. Hover Preview: When hovering with the mouse, the dot enlarges and highlights, and a preview card containing the timestamp and text appears on the left. Text longer than 3 lines is automatically truncated, with a fade-in and upward-floating animation.
  3. Click-to-Jump: Clicking a dot jumps to the corresponding message. If the message has not been loaded yet, the plugin automatically triggers the “load earlier” operation and continues loading page by page until the target message is reached.
  4. Full History: The data is read directly from the session log and does not depend on the content currently loaded in the front-end window, so it can index all historical records.
  5. Skin Adaptation: The colors are fully based on DSH semantic tokens and change according to the DeepSeek theme or any skin (such as Pinkie or Dragonkin).
  6. Latest Message Highlight: The latest dot is displayed brighter and more prominent.
  7. Scrollable Index: When the message volume is very large, the dot column supports internal scrolling, with gradient fade-out effects at the top and bottom ends.

Typical Usage

In a long conversation, use the wheel to scroll inside the dot column to quickly browse historical messages. Hover over a dot to view the detailed content of that message on the left. Click a dot, and if the message is outside the current view, the system automatically loads history and jumps to it.

Applicable Scenarios and Limitations

This plugin is suitable for developers who frequently need to switch context in long conversations. Two limitations are worth noting: first, when jumping to very old, unloaded history, it may require page-by-page loading and may cause brief stuttering due to DSH’s front-end pagination mechanism (50 items per page) and the absence of virtual scrolling; second, the dot column is anchored to the right edge of the conversation area, so its position may shift too far to the right in narrow windows or ultra-wide layouts. It is recommended to use it when the window width is greater than 800px.

Conclusion

dsh-msgrail provides lightweight navigation assistance for DSH users. The plugin source code and documentation are located at: GitHub, and the community catalog page is: SkillHub.