investigate

Systematic diagnosis for unknown failures — local environment, tool setup, CI vs local divergence, hook misbehavior, and runtime anomalies. Gathers signals broadly, ranks hypotheses, uses adversarial review (Codex or foundry:challenger) for ambiguous cases, probes each, and reports root cause with a recommended next action. NOT for known code bugs (/develop:debug (requires develop plugin)) or config quality (/foundry:audit). TRIGGER when: unknown failure with no Python traceback — hook not firing, CI passes locally but fails remotely, background agent stalled, behavior inconsistent with config; phrases: "not working but config looks right", "hook not triggering", "why isn''t X running". SKIP: Python traceback present (use develop:debug (requires develop plugin)); known code bug with repro (use develop:fix (requires develop plugin)); pure config quality check (use foundry:audit).