phxinvestigate

# Investigate Bug Investigate bugs using the Ralph Wiggum approach: check the obvious, read errors literally. ## Usage ``` /phx:investigate Users can't log in after password reset /phx:investigate FunctionClauseError in UserController.show /phx:investigate Complex auth bug --parallel ``` ## Arguments `$ARGUMENTS` = Bug description or error message. Add `--parallel` for deep 4-track investigation. ## Mode Selection Use **parallel mode** (spawn `deep-bug-investigator`) when: bug mentions 3+ modules, spans multiple contexts, is intermittent or involves concurrency, or user says `--parallel`/`deep`. **Otherwise**: Run the sequential workflow below. **Avoid confirmatory subagents**: Do NOT spawn parallel subagents to "verify" findings you already identified in the main context. If Step 3-4 already identified the root cause with high confidence, present it directly — don't spend ~80K tokens on 4 subagents to confirm what's already obvious (confirmed waste: session c135330a). ## Iron Laws 1. **Read the error message literally first** — Most bugs tell you exactly what's wrong; resist the urge to theorize before reading what the system is saying 2. **Check the obvious before going deep** — Compile errors, missing migrations, atom/string mismatches explain 80% of bugs; exhausting the Ralph Wiggum checklist saves hours 3. **Check changeset errors before UI debugging** — Silent form saves are almost always `{:error, changeset}` with validation failures, not viewport or JS issu...