dsh-agent-blackbox: Observe Agent Sessions in the DeepSeek Harness Sidebar

What Does It Do?

Blackbox (agent-blackbox) is a DSH plugin for DeepSeek Harness that puts the agent-blackbox dashboard directly into the DSH sidebar, so you can view live sessions, timeline replay, and cross-session cost overviews inside the app with a single click. It removes the hassle of switching between terminal and browser and spinning up extra processes or ports just to inspect agent behavior. The plugin mounts the core HTTP routes under the /blackbox prefix of DSH's own webServer, staying same-origin with no extra process or port. All data stays local: the plugin only reads local session files, with no network requests and no telemetry.

Core Features

• Live monitoring: sessions being written refresh incrementally, with a LIVE indicator and events and clock advancing with the session.
• Timeline replay: zoom and box-select on the timeline, tool waterfall, and event inspector, with events and tools revealed step by step during playback.
• Attribution: per-agent tool calls, tokens, and cost, plus blocking relationships.
• Cross-session overview: cost rankings grouped by runtime or project, with one click switching to the matching session.
• Same-origin embedding: the sidebar panel opens in embed mode with its own top bar hidden, and can also open in a new window for dual-screen setups.
• Bundled build artifacts: the published package ships compiled core and frontend, so no separate agent-blackbox install or local build is needed.

How to Use This Plugin?

After enabling it in DSH and restarting, a Blackbox ▣ entry appears in the left sidebar; click it to open the panel, which defaults to the most recently active session. Clicking a row on the overview page switches to that session; use "open in new window" inside the panel for dual-screen or multi-monitor setups. On the replay page you can zoom and box-select the timeline and play it step by step, using the tool waterfall and event inspector to locate issues. Cost estimates rely on a local pricing table, and unknown models are excluded from totals; sessions over 24 MB load only the trailing 8 MB window, so early tools do not appear in replay. Restart DSH after upgrading the plugin, and just refresh the panel when only frontend changes are involved. The plugin is maintained by JasperPengC under the MIT license.

How to Troubleshoot This Plugin?

If the Blackbox entry does not appear in the sidebar, the host code usually has not been reloaded; restarting DSH restores it. If features misbehave after upgrading the plugin, restart DSH first, since host code loads at startup. When the panel content is stale and only frontend changes are involved, refresh the panel instead of restarting. Missing early tools in session replay is a known limitation of large sessions that load only the trailing window; follow the official instructions to handle it.