Introduction

DeepSeek Harness (DSH) adopts a plugin-based architecture with a rich community plugin ecosystem. When developing or debugging agents, typically only the most recent few dozen conversation messages are rendered, making earlier instruction records difficult to review. This can reduce efficiency when viewing long session context or locating historical instructions.

dsh-command-rail is a plugin for the DSH web interface. It generates a vertical column of low-contrast instruction bars along the left edge of the conversation area, creating an instruction history rail similar to Codex. Instead of relying on the current DOM rendering window, it fetches complete historical data through the official client API, ensuring every user instruction has a corresponding marker.

Core Features

Full History and Data Source

The plugin fetches the full dataset through the official client API (such as connection.api.sessions.history) instead of reading the DOM only. The DOM retains only a window of roughly the most recent 50 events, but the rail display is not limited by this.

Interactions

  • Hover to view: When hovering over a rail bar, the bar becomes wider and brighter, and a Popover appears showing a summary of the current instruction (formatted as “Instruction N / M”). Even if the instruction has not been loaded into the DOM, its summary can be viewed as long as it exists in the history.
  • Click to jump: Clicking a bar smoothly scrolls to the instruction. If the target instruction is not within the current window, the plugin loads older history page by page through sessions.scope(id).conversation.loadOlder() until the message enters the DOM, then performs the jump and highlights it.
  • Current position highlight: The bar corresponding to the current reading position remains highlighted in the brand color. DOM rows and historical entries are aligned by text signature.

Robustness and Adaptability

  • Session switching: The plugin subscribes to the sessions list, automatically detects session switches, and redraws the history.
  • Fallback handling: When the history API is unavailable, it automatically falls back to DOM collection mode to ensure the rail does not disappear.
  • Adaptive layout: When there are many instructions, bar height and spacing are progressively compressed (down to a minimum of 2px); when instructions exceed 400, uniform sampling is applied automatically to avoid an overly crowded interface.

Install and Enable

Use the following command to install the plugin:

dsh plugin --profile desktop add dsh-command-rail-0.3.1.tgz

Notes:
1. Newly installed plugins require a restart of DSH Desktop to take effect on first installation.
2. Updates for already installed plugins support HMR (Hot Module Replacement) and do not require a restart.
3. When updating with pnpm, if the version number has not changed, pnpm will skip reinstallation; in this case, the version number must be manually bumped.

Typical Usage

  • Hover over the instruction bar on the left to view the summary of that instruction.
  • Click the corresponding bar, and the page will smoothly scroll to and load that instruction. If the instruction is older, earlier historical records are automatically loaded.

Use Cases and Considerations

This plugin is suitable for developers who frequently need to trace back through long sessions and review the context of historical instructions. Because the plugin runs with the permissions of the current DSH process, it is recommended to review the source code and license (MIT) before installation.

For more information or to submit feedback, visit the Community Directory or the GitHub repository.