DeepSeek Harness Plugin: dsh-session-pin

`dsh-session-pin` is a sidebar session pinning plugin purpose-built for DeepSeek Harness. It allows users to pin important conversations to the top of the sidebar for persistent, cross-workspace access without manually editing configuration files. The plugin leverages Codex-style interactions, integrates an archive lifecycle, and neither consumes tokens nor stores sensitive data. Installation requires specific version prerequisites. It only persists session IDs and automatically restores the default state after uninstallation, providing a lightweight and efficient solution for multi-session management.