dsh-zen-spoof: A DeepSeek Harness Plugin for Directly Connecting to OpenCode Zen Free Models

The dsh-zen-spoof plugin bypasses the DSH native adapter by directly registering the `opencode` route, resolving the header override issue and enabling use of OpenCode's free tier. After installation, manually edit the configuration file to comment out the conflicting `opencode` provider. The plugin supports automatic model discovery, thinking-mode parsing, automatic error fallback, and credential hot updates, is compatible with any DSH version, and requires no additional patches.