DeepSeek Harness v0.1.5-alpha.1
DeepSeek Harness v0.1.5-alpha.1: Sidebar & Session V3
- Author
- DeepSeekAgent.io Editorial Team
- Published
- Updated
DeepSeek published the dsh-v0.1.5-alpha.1 GitHub pre-release on September 8, 2026 and released the exact version to npm. It introduces an experimental right Sidebar and dynamic system-prompt updates, upgrades the Session format to V3, and changes the Agent and Inbox plugin APIs.
As of September 10, npm latest and next remain on 0.1.2-rc.1. Version 0.1.5-alpha.1 is a pre-release and requires an explicit version selection.
Release and installation status
| Check | Status |
|---|---|
| GitHub Release | v0.1.5-alpha.1, marked Pre-release |
| Published | September 8, 2026 at 16:16 UTC |
| Exact npm version | @deepseek-ai/[email protected] |
npm latest / next | 0.1.2-rc.1 |
| Later alpha | 0.1.5-alpha.2 is available |
Pin the version when testing this build:
npx @deepseek-ai/[email protected] web
Experimental right Sidebar
The Web app gains an experimental right Sidebar with tabs, split panes, and fullscreen. File links and model-produced files can open in the Sidebar, while the former Detail panel is removed.
This creates a foundation for completing work in a conversation and inspecting the result in the same interface. Alpha.1 supplies the container and file entry points. Alpha.2 follows with Markdown, code, HTML, PDF, and image previews plus explicit file delivery.
Dynamic system prompts and KV Cache
DSH can update a system prompt without invalidating KV Cache when the model configuration explicitly declares support. Long-running sessions and runtime state updates may benefit, although plugins cannot assume identical behavior across every provider.
Session format V3
Resuming a supported historical Session generates a new-format log while preserving the original file. V3 records system prompts in message history and migrates legacy PTC events and code preset references.
Sessions upgraded to V3 cannot be read by downgrading to an older build. Custom log readers, backup utilities, and Session analytics must adapt. Back up Sessions and test open, continue, compact, fork, and recovery paths before adoption.
Plugin API changes
Plugin authors have two main migrations:
ctx.agentis removed; callers pass the Agent explicitly.Inboxbecomes a type interface. Plugins access pending messages throughagent.inbox, whilehasPendingandclaimleave the public API.
The release also corrects ownership of continuable subagents so they do not participate in root-only scheduling as root Sessions.
Experience improvements and fixes
- Optional Codex and Claude Code subagent runtimes are updated.
- Session statistics split turns and speed from detailed token and cache-hit data.
- Assistant messages can render local images referenced by absolute POSIX paths.
- A model cannot resume a goal paused by the user.
- npm installs on macOS and Linux no longer require a local
fs-extbuild.
Upgrade guidance
| Scenario | Recommendation |
|---|---|
| Daily use | Stay on npm default 0.1.2-rc.1 |
| Sidebar evaluation | Test the later 0.1.5-alpha.2 build |
| Session tooling | Validate V3 migration and downgrade limits on a copy |
| Agent or Inbox plugin development | Apply the alpha.1 API migrations |
Related reading
- DeepSeek Harness v0.1.5-alpha.2: file delivery, previews, and Agent Teams
- DeepSeek Harness v0.1.3-alpha.2: subagent controls and long-session fixes
- DeepSeek Harness Agent Teams guide
FAQ
Does an unpinned install select alpha.1?
No. npx @deepseek-ai/dsh web currently resolves through latest, which remains 0.1.2-rc.1.
Does V3 delete old Session files?
The official notes say migration writes a new-format log and preserves the original. Important data still deserves an independent backup because older builds cannot read the upgraded Session.