The gun at rack id 16 learned a multiplier for Pattern's lead, separately
per range band. It was called BITBRAIN and shipped a TR_BITBRAIN_* prefix,
which is why the name read as a neural network it no longer contains.
guns/bitbrain_gun.nim -> guns/lead_gain.nim (rack id 16 UNCHANGED)
RackGunNames[16] BITBRAIN -> LEADGAIN
TR_BITBRAIN_* knobs -> TR_LEADGAIN_*
[bb] log line -> [lg]
BACKWARD COMPATIBILITY is mandatory: the live .env carries
TR_RACK_BITBRAIN=both, TR_BITBRAIN_GAINS, TR_BITBRAIN_MEM=decay and
TR_BITBRAIN_LOG=1, and those must keep behaving identically. The new ADE+SBC
gun (next commit) claims the BITBRAIN name and the TR_BITBRAIN_* prefix, so
the namespace is disambiguated by ONE deterministic switch, TR_BITBRAIN_NET
(default 0):
TR_BITBRAIN_NET unset/0 -> LEGACY: the 14 frozen legacy suffixes are aliases
for TR_LEADGAIN_*, and TR_RACK_BITBRAIN still
selects rack id 16. One [depr] line on stderr
names the new spelling of each honoured knob.
TR_BITBRAIN_NET = 1 -> the TR_BITBRAIN_* names belong to the new gun.
The legacy suffix set and the new gun's knob set are DISJOINT, so no name is
ever claimed twice; the new name always wins over its alias.
Parity: shipped rack is still onlyPattern, shipped movement is still strafe.
Guards unchanged: test_env_report 25, test_rack_membership 48,
test_tm_pattern_registration 20, test_lead_gain_registration 13 (was
test_bitbrain_registration), test_bitbrain 56, test_gun_harness 39,
test_tfil_commit_env 30. New: test_lead_gain_legacy 24.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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