DeepSeek Harness
Core Facts
DeepSeek Harness is open-sourced under the MIT license, with all source code publicly available and completely free.
The DeepSeek Flash version is a distilled model optimized for low-latency scenarios, trading some complex reasoning capability for faster response speeds and lower token unit prices.
DeepSeek Harness supports hot-plug capability, allowing plugins to be installed without restarting, unlike VS Code.
Timeline (last 90 days)
The Flash Presets plugin does not take effect automatically once installed; V3 must be manually selected in the mode menu for each new conversation, and a restart is required after installation.
The Flash Presets plugin includes no tools; it is a preset: switch to PTC mode plus add 13 rules.
PTC mode is hidden by default and only appears in the mode menu after turning on "Show Code Workspace View" in settings.
Across 51 test runs, with the same settings and the same task, the most expensive run cost more than 5 times as much as the cheapest run.
In PTC mode, the Ops plugin found the answer in a code file of more than 4000 lines at more than 30% lower cost than not installing it.
In tests where Billion Context conversations grew to 300,000 tokens, compression ran 4 to 11 times per pass, and conversations only reached 70,000 to 140,000 tokens at most, but in terms of cost, compared with not installing it, four passes showed no discernible difference, two passes were cheaper, and two passes were more expensive.
In PTC mode, the Ops plugin fixing a set of interdependent code files actually cost 20% more than not installing it.
Across the three test runs, Flash Presets was about 20% cheaper than not installing it, with all answers correct.
In PTC mode, the Ops plugin found the single failing item in a test log of more than 2000 lines at less than half the cost of not installing it.
New accounts in the DeepSeek Harness settings interface receive an official 6 yuan API trial credit, and can switch to third-party model providers or connect to locally deployed models.
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All Facts (20)
DeepSeek Harness is open-sourced under the MIT license, with all source code publicly available and completely free.
90%VerifiedThe DeepSeek Flash version is a distilled model optimized for low-latency scenarios, trading some complex reasoning capability for faster response speeds and lower token unit prices.
90%VerifiedDeepSeek Harness supports hot-plug capability, allowing plugins to be installed without restarting, unlike VS Code.
85%VerifiedDeepSeek Harness offers multiple working modes, forming a spectrum between autonomy and controllability.
85%VerifiedThe core design of DeepSeek-Harness is the Codis kernel, through which models, tools, skills, sessions, sandboxes, storage, and everything else are loaded, unloaded, and have their dependencies managed as plugins.
85%VerifiedDeepSeek Harness's Web UI supports switching between multiple modes including code mode, minimal mode, and creator mode.
80%VerifiedDeepSeek officially positions Harness as a Developer Preview.
80%VerifiedDeepSeek Harness only requires installing Node.js and entering a single command to run in a browser, achieving out-of-the-box usability.
80%VerifiedThe core design philosophy of Harness is 'everything is a plugin,' with all components—including models, tools, cache, sandbox, and UI—fully pluggable and replaceable.
80%VerifiedDeepSeek Harness adopts a plugin-based architecture in which the model, tools, session sandbox, and the Agent main loop itself can all be swapped out and recombined.
80%VerifiedThe core design philosophy of DeepSeek Harness is to treat everything as a plugin, including tools, skills, and drawing functionality.
80%VerifiedPTC mode (Programmatic Tool Composition) has the model generate a TypeScript program that combines multiple tool calls and executes them all at once in a sandbox environment.
80%VerifiedDeepSeek Harness provides end-to-end traceability, recording the complete trajectory of every step of system operation.
80%VerifiedDeepSeek Harness is currently in a developer preview stage; the official team has explicitly stated that breaking changes will occur, making it not yet suitable for direct deployment to stable production environments.
80%VerifiedConfiguring DeepSeek Harness requires pasting the API Key into the Edit DeepSeek input field in the model options on the settings page and saving.
80%VerifiedDeepSeek Harness采用TypeScript编写
80%VerifiedDeepSeek Harness is written in TypeScript, and installation requires a Node.js environment (tested with Node.js 24).
80%VerifiedDeepSeek is developed by DeepSeek (深度求索) company.
80%VerifiedEvent-driven architecture is a system design paradigm centered on events, in which components communicate by publishing and subscribing to events, achieving decoupling.
80%VerifiedDeep Agents itself is a harness, that is, an agent loop.
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