Derive the lineup K-rate free, and fingerprint the cap fix

Two premise corrections first. Pitcher stuff features have NOT proven solo
through the gate -- every one was refused on sample (n=57 against 500). Four
exceed the effect-size bar (arm angle -0.250, whiff +0.213, k rate +0.206,
chase +0.195), which is why they are worth pursuing, but clearing one of three
thresholds is not passing. And the carrier was not blocked only on the lineup
input: that input was built and measured last session at 94.7% coverage. What
blocks it is n, and n was being throttled by the grading cap.

RUNG 1 IS DERIVED AND COSTS NOTHING. Opposing-team K-rate comes from joining
the opposing roster to the batter k_pct values already in statcast_aggregates
-- no new feed. The improvement this session is that it is PA-WEIGHTED: an
unweighted roster mean counts a 12-PA callup the same as an everyday starter,
which is not the lineup a pitcher faces.

That change alone reversed the term's sign. Unweighted, the lineup term HURT
the model (0.1738 -> 0.1285). PA-weighted, it HELPS (0.1738 -> 0.1953). Same
hypothesis, same data -- the derivation was the problem, not the signal, which
is the entire argument for deriving the best honest version before sourcing
anything. Head-to-head is now +0.2592 with a CI of [-0.0167, +0.5645], very
nearly excluding zero, at n=57.

Within archetype, the two strata come out with OPPOSITE signs -- FLAME
incremental -0.152, non-FLAME +0.145 -- and the pooled value (+0.077) sits
between them, which is the shape a conditional effect makes and is invisible
when pooled. That is what stratifying was for. But n is 20 and 24, the
standard error on a correlation there is about 0.22, and the direction
contradicts the theory that predicted a stronger effect for finesse arms. It
is recorded as a structure to re-test, not as a finding.

Rungs 2 and 3 are NOT triggered. A rung fails only once it has been fairly
tested, and Rung 1 is n-blocked rather than failed. Sourcing confirmed lineups
now would be paying for precision on top of a proxy we have not yet measured.

THE RESULT THAT DECIDES THE TIMELINE: yesterday's cap raise is fingerprinted
in production at 907 grades per snapshot, up from 334, with strikeouts going 6
to 17. That puts n>=500 for pitcher Ks about a week out instead of three
months. Operational note: the manual internal snapshot endpoint now 524s at
the Cloudflare edge because grading the full board exceeds 100s -- the run
still completes server-side (this very snapshot was written by a 524'd
request) and the cron is in-process, so a 524 there is not a failure.

Nothing proven, nothing calibrated, nothing shipped. The counter remains
anti-predictive on strikeouts at -0.064 and the skill model leads it by 0.26.

4,221 tests green (335 suites); web build exit 0.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01W1sivYNqY2TS5ftykmHBU9

BUILD-STATE.md

@@ -3,6 +3,27 @@
 ## Last Updated
 2026-08-03
 
+## Session 85 (2026-08-03) — Rung 1 derived free; the cap fix fingerprinted ✅
+Spec: `specs/lineup-k-rate-rung1.md`. 4,221 tests / 335 suites green, build exit
+0. Counter + batter cluster + pitcher engine byte-identical.
+- **CAP FIX VERIFIED IN PROD: 334 -> 907 grades/snapshot; strikeouts 6 -> 17.**
+  n>=500 for Ks is ~a week out instead of ~3 months. NOTE: the manual internal
+  snapshot endpoint now 524s at Cloudflare (>100s) but COMPLETES server-side.
+- **RUNG 1 DERIVED, zero new sourcing:** opposing-team K-rate from the roster
+  joined to batter k_pct we already ingest, 94.7% coverage — now PA-WEIGHTED.
+  That change flipped its contribution: unweighted HURT (0.174->0.129),
+  PA-weighted HELPS (0.174->0.195). Head-to-head delta +0.259, CI
+  [−0.0167,+0.5645] — nearly excluding zero, still INCONCLUSIVE at n=57.
+- **Within-archetype:** FLAME incremental −0.152, non-FLAME +0.145 — opposite
+  signs, invisible when pooled (+0.077). But n=20/24 and the direction
+  contradicts the theory. Structure to re-test, not a finding.
+- **Rungs 2/3 NOT triggered** — Rung 1 is n-blocked, not failed. Do not source
+  confirmed lineups.
+- **Nothing proven, nothing calibrated, nothing shipped.** Counter is still
+  anti-predictive on Ks (−0.064); skill model leads by 0.26.
+- **Next:** wait ~1 week for n>=500 + a statcast_history window, re-run, re-test
+  the strata at ~200/stratum, and give arm_angle a registry entry + mechanism.
+
 ## Session 84 (2026-08-03) — Pitcher engine built; the cap was eating the board ✅
 Spec: `specs/pitcher-engine-strikeouts.md`. 4,221 tests / 335 suites green, build
 exit 0. Batter model + counter byte-identical (verified by diff).