DeepSeek has released DeepSeek Harness version v0.2.1-rc1 on October 17th. This version is the first candidate release of the 0.2.1 series for its open agent runtime. The release notes on GitHub compile the main changes concerning users and developers since the release of v0.2.0-rc.2. Some of these improvements, including reasoning trace translation, the Git Worktrees plugin, and the Claude Code Mods compatibility layer, were previously presented in the alpha.1 and alpha.2 preliminary releases, as reported by Pandaily.
The main innovation is the expansion of plugin capabilities. Users can now find and install plugins from custom index sources, not just from the official list. The plugin manager has gained a 'Allow Agent to Create Plugin' function, which saves a draft in creation mode and only starts working after receiving a request from the user. Functions for enabling, disabling, deleting, and updating plugins now synchronize dependencies. With hot reload enabled, an updated or reinstalled replaceable plugin takes effect immediately; otherwise, the application requests a restart.
Additional plugins support minimal mode, while the official list allows installing Claude Code and Codex packages corresponding to the current release for headless profiles, SDKs, and ACPs. An experimental session state interface allows plugins to independently save and read their session records.
Progress was also made in model and context processing. Users can now set reasoning levels for each model via the interface instead of using a configuration file, utilizing custom model APIs. The pi-ai router manages system prompt updates within a session and dynamically adds or removes tools according to the model's capabilities. Minimal mode can read images and automatically compress long dialogues, while web and desktop applications have added the /compact command for manual compression. Global instructions can read the AGENTS.md file from the general agents directory, which is specified via the DSH_AGENTS_HOME environment variable.
A new working_directory tool has been introduced for developers, along with TypeScript and Python SDK interfaces for reading and switching the session working directory. The web version allows logging into DeepSeek via local HTTP, and secrets and tokens found in sent messages are masked by default. New sessions can be pre-filled with an unsaved prompt, and the Markdown preview displays the YAML header as a list of fields.
It is worth noting that an automated account on X reported the brief appearance of an entry labeled 'deepseek-v4.1-flash-1017' in the official list of DeepSeek API models before it was removed. The suffix corresponds to a dated naming scheme of earlier snapshots, such as V4-Flash-0731 and V4-Pro-0813. The same account noted that the public model deepseek-flash still points to V4.1 Flash, not build 1017. DeepSeek has not commented on the existence of such a snapshot or what it might change.