Task A — the gain region Phase 0 never covered (gain < 1). Extend the
prediction-quality ruler with gain 0.25/0.50/0.75 arms and a fixed causal
per-band arm. Full 70-run result: the hitProxy-argmax curve is
[1.00, 1.00, 1.00, 0.00, 0.00] — Pattern below 300 px, HeadOn above —
worth +0.13 pp at 300-450 and +2.16 pp at 450+ (0.0767 -> 0.0984). Lead
correlation is identical for every g>0 (Pearson is scale-invariant), so a
shrinking gain adds no lead information; and the least-squares optimum
[1,1,1,1,0.25,0.25] diverges from the hitProxy optimum because Pattern's
lead errors are bimodal.
Task B — rebuild guns/bitbrain_gun.nim as a lead-gain corrector:
aim = LOS + gain*(patternAim - LOS), gain learned online per range band by
ranking candidate gains on the hit-probability proxy (the observed lead
label via tmhObservedAt), gated to range >= 300 px. ADE+SBC output removed.
Offline (70 runs): Pattern below 300 px, +0.37 pp at 300-450, +1.90 pp at
450+ (hitProxy 0.0957 vs 0.0767), matching the fixed rule to within 0.27 pp
at 450+ and exceeding it at 300-450. ~0.0007 ms/tick marginal (old gun
~0.114 ms/tick). Default off; rack membership, env report and guard tests
(bitbrain 32, registration 13, rack 48, tm_pattern 20, env_report) unchanged
and green.
Ledger: docs/bitbrain_campaign.md Phase 1, including the three on-file
negatives and the causal-shippability note. No live claim.
New harness (common_libs/gun_harness/prediction_quality.nim +
common_libs/tests/run_prediction_quality.nim): per-gun single-tick aim error in
degrees against the true continuous interception point on the recorded
live-vs-real-DrussGT corpus (/tmp/tfil_ab2/out, 70 runs, 899607 ticks), per
range band, with the hit-probability proxy mean(|err|<=atan(18/range)).
Validated: recorded hits separate from misses 13.34x px (reference 11.59x),
perfect-oracle max |err| = 0, correct ordering on synthetic ground truth, two
full runs byte-identical. Fixed a wrap180 bug (Nim float mod keeps the dividend
sign) that inflated the negative error tail.
Bar (mean|err| deg [hitProxy] at 450+): Pattern 16.19 [0.077], naive-linear
22.86 [0.054], TMHorizon 16.20 [0.076], BitBrain 16.20 [0.077], static HeadOn
12.33 [0.098], oracle 0 [1.0]. Lead-gain sweep on Pattern is a dead end (1.0
wins every band). Naive-linear applies ~1.8x Pattern's lead but carries no more
lead information (corr 0.178 vs 0.165) and is strictly worse. Ledger:
docs/bitbrain_campaign.md. All verdicts remain live-only.
SirStone