dsh-calendar: Global Session Interaction Calendar for DeepSeek Harness

`dsh-calendar` is an MIT-licensed plugin for DeepSeek Harness that addresses the difficulty of reviewing global interaction history during multi-session parallel development. It provides a root-scoped calendar view that aggregates user messages, assistant replies, and tool invocation events across all sessions. The plugin supports real-time updates, historical backfilling, and rolling 90-day memory management. Users can quickly filter sessions by date through the sidebar calendar, or query JSON data via HTTP endpoints and SSE channels. Installation requires the `dsh plugin` command, after which a Calendar entry appears at the bottom of the sidebar. Note that the plugin only works in the Web client and that pnpm version compatibility should be considered.