Introduction

DeepSeek Harness (DSH) is a framework for agent development. In interactive debugging or demonstration scenarios, it is often useful to let an LLM directly inspect local image files. A common traditional approach is to convert images into Base64 strings, but this can significantly bloat session logs and increase network transfer overhead. The dsh-plugin-show-image plugin solves this problem by providing a global tool and an on-demand HTTP route. It can render local images inline in the conversation flow without consuming model context.

Core Features

Maintained primarily by justhalfbit, this plugin provides the following capabilities:

  1. Inline image rendering: Display local images directly in the conversation flow without leaving the session interface.
  2. Click to enlarge: Thumbnails can be clicked to view the full-size image in a fullscreen Lightbox overlay. You can close the overlay by clicking anywhere or pressing Escape.
  3. On-demand HTTP transfer: Image bytes are transferred through a dedicated HTTP route (GET /show-image?path=…). Images are not Base64-encoded, and the image data does not enter the session log.
  4. Zero dependencies, zero build: Written in plain JavaScript with no npm dependencies, no build step, and no TypeScript.
  5. Security guards: Enforces an 8 MB file-size limit and an extension whitelist that prevents prototype-chain pollution. Unsupported formats are rejected.
  6. Fully reversible: All side effects (tool registration, HTTP routes, card renderers) are bound to the plugin fiber and are cleaned up when the plugin is removed.

Installation and Setup

Before installing, ensure that DSH is installed and that pnpm is available in PATH.

dsh plugin --profile web add github:justhalfbit/dsh-plugin-show-image

After installation, restart dsh web for the configuration to take effect. The removal command is:

dsh plugin --profile web remove dsh-plugin-show-image

Usage

After installing and restarting, the plugin registers the global tool show_image in every session. You can directly instruct the Agent:

Show /path/to/image.png

After the Agent calls the tool, the image is rendered as an inline card in the conversation flow. Click the image to view the full-size version.

Limitations and Notes

  1. Runtime environment: Only available in the dsh web (browser GUI) profile. It is not available in tui or headless modes. This is because the plugin depends on the webServer service, and registering an unrenderable tool in a terminal without a rendering surface would mislead the model.
  2. Path resolution: Relative paths are resolved against the working directory of the DSH process, not the working directory of the current session. Use absolute paths wherever possible.
  3. Permission model: Any local process can read local image files through the GUI port, which is consistent with DSH GUI’s existing local trust model and should not require extra concern.

The plugin is fully open source under the MIT license. For additional technical details, a directory index, and the source repository, see the links below: