DeepSeek Harness released significant updates throughout September, progressing from version 0.1.2 through 0.2.0-rc.2. Major improvements focused on agent collaboration, file handling, workspace integration, and developer experience.
Agents and Automation
- Bidirectional agent messaging: Parent and child agents can now exchange follow-up messages seamlessly instead of one-way reporting, improving collaborative workflows.
- Continuable subagents with message control: Queue, edit, delete, steer, and stop individual or all queued messages before delivery, with visual sending state feedback.
- Subagent model selection: Choose provider, model, reasoning effort, and output limits through agent authorization or caller specification.
- Team mode expansion: Support for up to 16 teammates using the new spawn_teammate API for improved collaborative agent workflows.
- Asynchronous question mode: Agents can continue work independently while awaiting your response, streamlining long-running tasks.
Interface and Workspace
- Right sidebar with rich previews: Tabbed, split-pane, and fullscreen views for Markdown, code, HTML, PDF, images, Word, Excel, PowerPoint, CSV, and TSV files with direct rendering in chat.
- Web terminal in sidebar: Multiple tabs, shell selection, and automatic recovery after page refreshes for direct command execution.
- Session management: Pin, archive, and restore sessions with filtering and detailed change diffs with synchronized scrolling.
- Plugins page: Install, configure, and toggle plugins instantly within the UI, with support for custom registries and persistent plugin management.
- Open in external apps: Launch the workspace in any installed editor, IDE, terminal, or file manager; open folders and files with your preferred local applications.
Models and Providers
- DeepSeek-V41-Flash as default: New default model supporting text, images, and in-history prompts with improved capabilities.
- Model discovery and metadata: Expanded support for custom providers with automatic filling of missing metadata like context windows and output limits; fuzzy matching and keyboard navigation for model search.
- Unified model provider setup: Streamlined API switching and direct account model editing in Settings; web search for DeepSeek account models without separate API keys.
Developer Experience
- Headless JSON mode: Read tasks from standard input, resume sessions via ID, and stream run events as newline-delimited JSON for automation and scripting.
- Hybrid execution: File, command, and PTC tools run locally while accessing remote SSH workspaces, enabling seamless hybrid setups.
- Browser automation: Experimental support through Playwright, Chrome DevTools, and Stagehand backends with computer use, screenshots, and local driver control.
- Desktop bundling: macOS and Windows Desktop now bundle the dsh command directly, eliminating separate Node or pnpm installation requirements.
Some other features were also released this month but are not listed here.