DeepSeek Harness Message Navigator: Codex-like Session Navigation for the Web UI

DeepSeek Harness Message Navigator is a browser-based plugin designed to address the challenge of quickly locating and reviewing context in long conversations. Using a Codex-like ruler navigation on the left, it generates interactive markers for each regular user message. Its core features include precise ruler generation, automatic loading of complete history, visual follow positioning, and keyboard navigation support. It is compatible with dark mode, utilizes Harness theme variables, and runs entirely locally without storing data. Installation requires DeepSeek Harness version 0.1.0-rc.6. The plugin supports mouse hover preview, click-to-jump, and arrow-key navigation, providing developers with an efficient long-conversation browsing experience.