Introduction

When developing agents with DeepSeek Harness (DSH), developers often need to process data formats such as JSON, URLs, and Base64 in the Web Composer. Manually converting this data is not only time-consuming but also error-prone. dsh-dev-toolbox is a local toolbox designed to address this pain point. It is integrated directly into the Web Composer toolbar and provides a set of instant conversion features without calling a model or using network transmission.

Plugin Overview

This plugin is maintained by Qingzhou-Joshua and is a standalone npm package. It runs in the browser context and handles conversions for JSON, URLs, Base64, timestamps, and UUIDs. Its core value lies in “localization” and “immediacy”: all operations are completed within the current session, and neither inputs nor outputs are written to disk.

Core Features

The plugin provides the following conversion features:

  • JSON Handling: Supports formatting (beautified output), minifying (single line), validation (parsing check only), escaping (converting text into a JSON string), and unescaping (parsing a JSON string). It also supports regular expression search in the output results (up to 2,000 matches) and toggling reading view.
  • URL Tools: Supports percent-encoding and decoding, as well as mutual conversion between query strings and JSON objects.
  • Base64 Encoding/Decoding: Supports conversion between UTF-8 text and standard Base64. During decoding, whitespace characters in the payload are ignored, making it easy to paste log fragments directly.
  • Timestamp Conversion: Supports 10-digit Unix seconds, 13-digit Unix milliseconds, fractional seconds, and text formats supported by Date.parse (such as ISO). After input, it displays Unix seconds, milliseconds, ISO time, and local time simultaneously.
  • UUID Generation: Generates UUID v4.

Installation and Enabling

The installation command is as follows:

dsh plugin --profile web add github:Qingzhou-Joshua/dsh-dev-toolbox

Before installing, make sure the environment meets the following requirements:
* The Node.js version is ^22.19.0 || >=24.0.0.
* If you are using pnpm >= 10, the first installation may fail because the scripts are blocked by pnpm. In that case, copy the allowBuilds key indicated in the error message into ~/.dsh/profiles/web/pnpm-workspace.yaml, and then run the installation command again.

After installation, run dsh web to start the Web UI. After refreshing the page, a code icon will appear to the right of the + button in the Composer toolbar. Click it to open the toolbox panel.

Usage Instructions

After opening the toolbox panel, enter content and click the corresponding button to obtain the result. At the bottom of the panel, there are three common actions:
1. Load from composer: Copies the current draft from Composer into the toolbox input field (excluding the UUID).
2. Copy output: Copies the output result to the clipboard.
3. Insert into composer: Inserts the output result back into Composer. If the draft is empty, it replaces the draft; otherwise, it appends a newline at the end and closes the panel.

  • JSON Search: In the JSON tab, search defaults to literal matching. After enabling “Regex”, JavaScript regular expressions are used. Press Enter to jump to the next match, and Shift+Enter to jump to the previous match.
  • Reading View: Click the expand icon next to the output label to switch the toolbox to reading view, retaining only the output content and search functionality while maximizing the output area.
  • Input Limit: A single input exceeding 512 KiB characters will be rejected to prevent page lag.

Notes

  • The plugin runs with the permissions of the current DSH process. Review the source code and license before installation.
  • Do not run pnpm run build in the harness root directory.
  • The plugin’s input and output data are not written to disk.

Summary

dsh-dev-toolbox is a lightweight development assistant suitable for developers who frequently need to convert data formats. By processing locally, it reduces network overhead and model calls, improving development efficiency in the DSH Web Composer. For more details and the source code, see the GitHub repository.