Learning tier item 2: one pre-registered directional Jev measurement (not before 0.5.x closes) #39

What this is

One pre-registered, directional measurement of TypeSafe's Jev as a filter over harness-proposed struggle candidates, on the repo's 13-session human-labelled gold. No product wiring, no adopt/reject clause, no Jev call before the pre-registration commit. Plan §4 (docs/architecture/learning-tier/plan-2026-09-19.md): S2-RULER, S2-PREREG, S2-COV, S2-TRAIN, S2-HELDOUT.

Gate

Not before milestone 0.5.x is closed (owner decision 1, 2026-09-23). Branch feat/jev-struggle-eval is cut from main on that day, and decision 4 (the Jev spend cap; estimate under $1 at $0.042/Mtok plus ~13–26 turns of the owner's subscription for candidate generation) is decided then, not before.

What Stage 0 established (docs/architecture/jev-judge/receipts/stage0-access-2026-09-19.md)

Jev scored the four pedagogical teach-back dimensions where a human would at high confidence but was blind to a planted accuracy error — so Jev is never a sole accuracy judge; the harness LLM supplies accuracy.

Definition of done

Plan §4 finish lines, each committed as a receipt; the measurement reported directionally with its coverage gate; nothing in the product changed by this issue.