investigate

# 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`. Before spawning it, determine the effective maximum nesting depth. Use an explicit positive-integer `CLAUDE_CODE_MAX_SUBAGENT_SPAWN_DEPTH` value first; when it is unset, inspect `claude --version` (the default is 1 in 2.1.217–2.1.218 and 3 in 2.1.219+). If the version is unavailable, conservatively use 1. At depth 3+, use the `deep-bug-investigator` orchestrator. At depth 1 or 2, keep orchestration in this main session: spawn the four focused tracks (reproduction, root cause, impact, fix strategy) directly in one parallel batch, wait for all four, then synthesize their evidence. Never spawn an orchestrator that cannot delegate. **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, pr...