dsh-turn-doctor: DeepSeek Harness Turn Failure Diagnostic Plugin

DSH-turn-doctor is a diagnostic plugin for DeepSeek Harness that helps identify the causes of failures such as request timeouts. It measures time to first byte, byte inter-arrival gaps, and total request time, analyzes multi-layered timeouts across idle watchdogs, SDKs, HTTP timers, and tool calls, pinpoints the specific failure point, and provides remediation suggestions. The plugin is strictly for diagnostics: it does not perform retries or modify configurations, and its verdicts remain in memory, helping developers avoid blind configuration changes and resolve issues quickly.