Why Tree

A Why Tree is 5-Whys grown up. Naive root-causing follows a single thread, stops at the first plausible cause, and cites nothing. A Why Tree (Goldratt's Current-Reality Tree) does the opposite: it searches the whole branch-space in parallel, grades every node by the evidence actually behind it, tries to refute its own load-bearing branches, and converges on the ONE constraint that, if removed, unblocks everything else - plus the negative branches (fixes that backfire) and the single cheapest test that would fork-decide the conclusion.

The output is a self-contained interactive HTML tree + a one-page decision doc (constraint located / do this / don't do that / cheapest test).

This rigor costs tokens - real Deep field runs have landed at ~90-115 agents / 5.5-6.6M tokens. The skill is transparent about that cost and gates on a depth choice before launching (Phase 0), and when the depth isn't obvious it offers a cheap scout gate (Phase 1.5) that measures whether the swarm is even needed. Do not skip the gate.

What makes it different from a normal root-cause analysis (read first)

1. Branch-space first, depth second. Map all the candidate "why"s from many independent lenses before deepening any one. A single-thread analysis finds the first cause; a tree finds the real one.
2. Every node is graded. Each node carries an answer-kind (is this MEASURED, an INSTANCE, EXTERNAL, a CLAIM, an INFERENCE, a HYPOTHESIS, or just FRAMING?) + a confidence grade + a citation — and every MEASURED node additionally carries a validation state (raw/validated/triangulated/contested): a number is not yet a fact until its pipeline is checked. Ungraded assertions are banned. See references/answer-kinds.md.
3. Refute before you trust. Load-bearing branches face an adversarial pass that tries to kill them. Branches that die are marked REFUTED/DOWNGRADED with the evidence that killed them - kept visible, not deleted (they're the most useful part).
4. Converge to ONE. Goldratt: there is one constraint; everything else is noise. The tree forces convergence to 3-5 roots and names the single system constraint - often a policy/ownership problem wearing a tooling costume.
5. Honest census. If the decisive nodes are still HYPOTHESIS (unmeasured), the tree says so out loud: "a map of where to look, not a verdict."

If you find yourself shipping five co-equal "root causes," a tidy single-thread chain, or a confident verdict built on unmeasured nodes - you did it wrong.