What problem does it solve? When blue rebuild or guix system reconfigure hangs after a channel update, it is hard to tell whether the cause is a shepherd control-fiber deadlock or a substitute proxy blackhole. This Skill provides a proven diagnostic playbook that distinguishes the two failure modes and gives copy-paste forensic commands plus recovery steps. ## Core Features & Use Cases - Deadlock vs. proxy discrimination: Identify shepherd 1.0.9 control-fiber deadlocks triggered by guix-daemon service restarts, and rule out mihomo proxy blackholes on substitute URLs using --no-substitutes tests and /proc/<pid>/environ inspection. - Forensic command set: Ready-to-run commands for process trees, proxy connection states (ss -tnp), herd responsiveness timing, and syslog evidence extraction. - Guix Home PATH drift repair: Locate surviving /gnu/store/*-profile directories and fix git: command not found after guix home reconfigures. - Use Case: After blue update bumps the guix package, your first rebuild freezes and every herd command hangs. Follow the playbook to confirm the shepherd deadlock via syslog, reboot to reset shepherd, then rebuild successfully. ## Quick Start Ask the agent to diagnose why my blue rebuild is hanging and whether it is a shepherd deadlock or a substitute proxy problem.
