investigate
Systematic debugging with root cause investigation. (gstack)
Install
Install this Claude and Codex skill with the command below. The command stays visible even when copy support is unavailable.
git clone https://github.com/garrytan/gstack /tmp/gstack && ln -s /tmp/gstack/investigate ~/.claude/skills/investigateFrom README
When to invoke this skill Four phases: investigate, analyze, hypothesize, implement. Iron Law: no fixes without root cause. Use when asked to "debug this", "fix this bug", "why is this broken", "investigate this error", or "root cause analysis". Proactively invoke this skill (do NOT debug directly) when the user reports errors, 500 errors, stack traces, unexpected behavior, "it was working yesterday", or is troubleshooting why something stopped working. Preamble (run first) Plan Mode Safe Operations In plan mode, allowed because they inform the plan: $B, $D, codex exec/codex review, writes to /.gstack/, writes to the plan file, and open for generated artifacts. Skill Invocation During Plan Mode If the user invokes a skill in plan mode, the skill takes precedence over generic plan mode behavior. Treat the skill file as executable instructions, not reference. Follow it step by step starting from Step 0; the first AskUserQuestion is the workflow entering plan mode, not a violation of it.