dsh-mt-download

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A multi-channel file downloader for DeepSeek Harness: 16-connection chunked downloads through aria2c, with an automatic fallback to a plain Node.js stream.

A DeepSeek Harness plugin.

Why this exists

When an agent downloads assets, models, videos or GitHub release archives, a single streaming connection has three recurring problems:

1. Slow — one connection leaves bandwidth unused, so large files take far longer and hover near the timeout.
2. Blocked — resources on Douyin, Bilibili and Xiaohongshu are hotlink-protected and return 403 without a matching Referer.
3. Broken TLS — Node.js uses the system trust store, so a damaged certificate chain on Windows makes HTTPS downloads fail outright.

This plugin folds all three into one tool. The agent supplies a URL and a destination path.

What it does

• Primary channel — drives a local aria2c JSON-RPC endpoint (default 127.0.0.1:16801) with 16 parallel connections. The daemon is started on demand and costs nothing while idle.
• Fallback channel — if aria2c is missing or a download errors out, the file is streamed once through Node.js fetch so it still lands on disk.
• Hotlink handling — a Referer is injected per known host (Douyin, Bilibili, Xiaohongshu, Weibo, GitHub) together with a modern browser User-Agent. Callers can pass their own headers to override.
• Path resolution — the destination may be a file path, a directory, or a path with a trailing separator; for a directory the filename is taken from the URL.
• Reporting — returns the absolute path, byte count, elapsed seconds, average speed, and which channel actually delivered the file.

Install

Use github:643048695/dsh-mt-download in the Web UI plugin page, or:

dsh plugin --profile <profile> add github:643048695/dsh-mt-download

Configure

Set these under the plugin's config in the profile cordis.patch.yml:

Where aria2c comes from

The plugin does not bundle the aria2c binary — it locates and drives the copy already on your machine. Lookup order:

1. The aria2Path config value
2. Environment variables MT_ARIA2C_PATH / ARIA2C_PATH / DOUYIN_ARIA2C_PATH
3. aria2c on the system PATH
4. Common install locations (on Windows Program Files\aria2 and Motrix's bundled directory; on macOS/Linux /usr/bin, /usr/local/bin, /opt/homebrew/bin, and similar)

If none is found the plugin still works — it goes straight to the fallback channel.

Tool signature

download_file

Result:

{
  "success": true,
  "file_path": "C:\\path\\to\\file.bin",
  "file_size_bytes": 25098,
  "file_size_human": "24.51 KB",
  "duration_seconds": 1,
  "speed_human": "24.51 KB/s",
  "method": "aria2c (16 并发通道)"
}

On failure it returns { "success": false, "error": "..." } with the reason from both channels.

Notes and limits

• The aria2c daemon is spawned detached and is not shut down when the plugin unloads; the next download reuses it.
• Chunked downloads need server-side Range support. Without it aria2c degrades to a single connection rather than corrupting the file.
• Auto-injected Referer covers only a handful of hosts; pass headers for anything else.
• Direct HTTP/HTTPS links only — no page scraping, no m3u8 segmentation, no authenticated sessions.

Compatibility

Node.js >= 20. On the host side only tools.register is used, with no hard service dependency, so any DSH profile with a tool registry can mount it.

Development

npm install
npm test

Tests cover the pure helpers (size and speed formatting, filename inference, hotlink header matching) and touch neither the network nor aria2c.

License

MIT, Copyright (c) 2026 643048695.