{"slug": "i-tested-deepseek-harness-for-a-week-i-left-with-a-shipped-plugin-and-0-in-api", "title": "I tested DeepSeek Harness for a week. I left with a shipped plugin and $0 in API costs", "summary": "A developer built and shipped dsh-model-pricing, a plugin for DeepSeek Harness that adds per-million-token cost comparisons and cheapest-route badges to the harness's Settings page, after testing the tool for a week. The plugin was developed entirely inside DeepSeek Harness driven by Qwen3.8-Flash via a free API promotion, producing 28 commits and roughly 2,300 lines of code at $0 in LLM costs. The author says the harness's 'everything is a plugin' architecture, including its web UI and settings screen, is assembled from plugin contributions.", "body_md": "I came to DeepSeek Harness as a reviewer and left as one of its plugin authors,\n\nwhich is a fair measure of how the week went.\n\nThe hook is on the repo's first line: **\"Everything is a plugin.\"** Not the\n\nusual marketing meaning — not a config file with a couple of third-party hooks.\n\nIn DSH the agent hosts its own web UI as plugin packages; the settings screen\n\nwhere you pick and configure models is assembled from plugin contributions\n\n(this is the part I verified the hard way); even the optional subagents —\n\nCodex, Claude Code — ship as plugins you can add or drop. All of it loaded\n\nthrough manifests over a real extension API. I've poked at a lot of \"extensible\" tools. This one takes it literally, and poking at it turned into\n\nthe most fun I've had with an agent harness in a while.\n\nThe gap I kept feeling in Settings → Models was the two questions I ask before\n\nswitching providers every time: **what does this model actually cost per\nmillion tokens, and is a cheaper route to the *same* model available?** DSH\n\ntells you which models exist. It doesn't tell you what they cost.\n\n`dsh-model-pricing` closes that, and it lives *inside the harness's own Settings page* — because that's the point of testing the plugin system:\n\n`cheapest` badge: GLM-5.2, say,\nruns from $3.08 to $4.84 per 1M output tokens depending on the gateway — the\nsame model, 57% apart\nIt installs through the harness's own plugin manager — I never forked anything:\n\n```\nnpx -y @deepseek-ai/dsh plugin --profile web add dsh-model-pricing\n```\n\nHere's the part I didn't expect. I built the whole thing **using DeepSeek Harness, driven by Qwen3.8-Flash** through B.AI's current promotion — the one\n\nEight records shipped on day one; one of them describes the free model that\n\nwrote this plugin's UI.\n\n| priced rows / providers | 7,178 / 213 | \n| harness-catalog overlaid rows | 788 (30 disagreements flagged, not averaged) | \n| plan rows grouped & excluded from ranking | 175 | \n| promo records at launch | 8 (each with source URL + verification date) | \n| commits / files / LOC | 28 / 18 / ~2,300 | \n| wall-clock | ~22h, incl. overnight autonomous rounds | \n| LLM cost | $0 — free API promotion, re-verify date 2026-10-10 | \n| UI languages | en + zh (platform), ru (plugin) | \n\nIf you're curious about DeepSeek Harness the way I was: run it, then break into\n\nits settings page. The architecture is the product; the agent is very good at\n\nboth jobs, even on a model that costs nothing.\n\n```\nnpx -y @deepseek-ai/dsh plugin --profile web add dsh-model-pricing\n```\n\nRepo (docs, feature map, the promotion contribution rules — all public):\n\n[github.com/vitas/dsh-model-pricing](https://github.com/vitas/dsh-model-pricing)\n\n· npm:\n\n[dsh-model-pricing](https://www.npmjs.com/package/dsh-model-pricing) ·\n\nApache-2.0.", "url": "https://wpnews.pro/news/i-tested-deepseek-harness-for-a-week-i-left-with-a-shipped-plugin-and-0-in-api", "canonical_source": "https://dev.to/vitas/i-tested-deepseek-harness-for-a-week-i-left-with-a-shipped-plugin-and-0-in-api-costs-3d8j", "published_at": "2026-09-10 18:57:25+00:00", "updated_at": "2026-09-10 19:42:20.430034+00:00", "lang": "en", "topics": ["ai-agents", "ai-tools", "developer-tools", "ai-products", "large-language-models"], "entities": ["DeepSeek Harness", "dsh-model-pricing", "Qwen3.8-Flash", "B.AI", "GLM-5.2", "Codex", "Claude Code", "GitHub"], "alternates": {"html": "https://wpnews.pro/news/i-tested-deepseek-harness-for-a-week-i-left-with-a-shipped-plugin-and-0-in-api", "markdown": "https://wpnews.pro/news/i-tested-deepseek-harness-for-a-week-i-left-with-a-shipped-plugin-and-0-in-api.md", "text": "https://wpnews.pro/news/i-tested-deepseek-harness-for-a-week-i-left-with-a-shipped-plugin-and-0-in-api.txt", "jsonld": "https://wpnews.pro/news/i-tested-deepseek-harness-for-a-week-i-left-with-a-shipped-plugin-and-0-in-api.jsonld"}}