root-causelisted

# Root-Cause The discipline: build a feedback loop before theorizing, then let evidence kill hypotheses. Everything else is mechanical. Each phase has a gate — do not pass a gate that has not been met. ## Phase 1 — Build the loop Construct ONE command that reproduces the failure on demand. Cheapest construction that works, in order: failing test → request script (curl) → CLI invocation → headless browser script → recorded trace replay → minimal harness → bisect → differential run (old vs new). Exit gate — the command must be **red-capable** (fails while the bug lives), **deterministic** (same input, same result), **fast** (seconds, not minutes), and **agent-runnable** (no manual UI steps). Run it red. No red command, no Phase 2. ## Phase 2 — Shrink it Strip the repro to the smallest input and config that still fails. Each removal teaches what is irrelevant; what survives is implicated. Already minimal? Say so and move on. ## Phase 3 — Hypotheses List 3–5 hypotheses, one sentence each, each falsifiable by a specific observation ("stale cache after config reload — clearing the cache between runs makes it disappear"). Rank by likelihood × cheapness to test. Show the user the list before testing — non-blocking. ## Phase 4 — One variable Test one hypothesis at a time, cheapest first. Tag debug output `[DBG-xxxx]` with a random suffix per investigation so removal is one grep. Never change two things between runs of the loop. ## Phase 5 — Regression test before fix With