SirRoboGarage/docs/headon_longrange_live.md

HeadOn vs Pattern at long range — LIVE gate

Date: 2026-09-24 Branch: research/lead-targeting · commit: a82c864 · binary sha256: 9d20f530d6… (one frozen binary, git archive HEAD) Session: /tmp/ab_headon · 2 arms × 15 runs × 7 rounds = 210 rounds, conc=8 Fixtures committed: headon_longrange_ab_report.txt (ab_analyze), headon_longrange_bands.txt (range-band), headon_longrange_live_results.json (per-run + per-band counts). Arms: tools/ab/arms_headon.txt.

Direct answer

NO. The no-lead static gun does not beat Pattern live, overall or in any long-range band. It is not close: HeadOn won 0 of 105 rounds and dealt 14 dmg/run vs 279 (20× less), and at 450+ px it hits 0.4% vs Pattern's 9.2% (23× less). The offline ruler's headline — HeadOn has lower aim error and a better hit proxy than Pattern at 300+ px — is killed. The offline ruler was the only thing that predicted the opposite; this live A/B is the only thing that can confirm or kill it, and it killed it.

The TR_PATTERN_RAD_SCALE arms were skipped (the knob cannot express the lead hypothesis)

common_libs/guns/pattern_matcher.nim applyRadial moves the aim point along the unchanged bearing (selfX + dx/d*nd, selfY + dy/d*nd) — the direction dx/d, dy/d is untouched, only the distance changes. The fired bearing is aimAngle(self, pred) (ModularBot.nim:1208), so scaling the aim distance cannot move the bearing. The knob is a radial range correction, not a lead multiplier, and cannot express "less lead". Per the task rule, arms rad075/rad050 were skipped and the experiment ran as 2 arms × 15 runs.

HeadOn really does ignore bulletSpeed

common_libs/guns/head_on.nim:9 returns GunPrediction(x: state.enemyX, y: state.enemyY), never reading its bulletSpeed argument. The rack calls it for the selected power bin and the fire block takes the bearing straight to that point. So the premise holds: HeadOn applies zero lead, independent of power. The headon arm's liveness check passed (its env reached the boot report in 15/15 runs), so this was HeadOn and only HeadOn.

Primary result — damage/run and round wins [MEASURED]

arm	runs	dmg/run	dmgtk/run	round wins	win%	shots/run	hits taken/run
control (shipped Pattern-only)	15	279	211	48/105	45.7	785	93
headon (HeadOn-only)	15	14	228	0/105	0.0	580	72

Per-run damage (control): 263 307 294 221 290 235 327 262 330 312 274 292 288 281 217. Per-run damage (headon): 4 8 4 17 14 10 28 18 0 36 17 8 14 14 15.

metric	diff (control−headon)	perm p	method	MDE (abs)	MDE vs control mean
dmg/run	+265.7	<0.0001	MC/B=1,000,000 (se 0.0000)	35.8	12.8% of 279.5
round wins	+3.20	<0.0001	MC/B=1,000,000 (se 0.0000)	1.29	40.4% of 3.2

Mann-Whitney U cross-check p = 0.0000 on both. Round-level Fisher p < 0.0001 (anti-conservative). The effect is ~7× the damage MDE; this is not an under-powered null.

Hit rate by range band — the load-bearing breakdown [MEASURED]

Pooled over each arm's 15 runs; band = shooter→target distance at the fire tick (same bands as the offline ruler). HeadOn loses the long-range bands by a landslide — the whole-battle defeat is not a close-range artefact.

band (px)	control shots / hits / rate	headon shots / hits / rate
0–100	3 / 2 / 66.7%	1 / 0 / 0.0%
100–200	28 / 4 / 14.3%	97 / 8 / 8.2%
200–300	211 / 26 / 12.3%	469 / 12 / 2.6%
300–450	4590 / 565 / 12.3%	3701 / 21 / 0.6%
450+	6671 / 616 / 9.2%	4177 / 15 / 0.4%
ALL	11503 / 1213 / 10.5%	8445 / 56 / 0.7%

Per-band permutation test on per-run band rates (arm − control):

band	diff (pp)	p	method	MDE (pp)
100–200	+1.93	0.6609	exact	12.4
200–300	−12.12	<0.0001	MC/B=200,000	12.1
300–450	−11.84	<0.0001	MC/B=200,000	2.0
450+	−8.89	<0.0001	MC/B=200,000	1.1
ALL	−9.90	<0.0001	MC/B=200,000	1.0

The two long-range bands separate at 4–8× their MDE, overwhelmingly in HeadOn's favour being false. Note the 98%+ of shots that land at 300+ px, exactly as the offline ruler reported.

Offline ruler vs live [MEASURED]

source	metric	Pattern 300–450	HeadOn 300–450	Pattern 450+	HeadOn 450+
offline prediction_quality_results.txt	meanAbs err (deg)	17.53	14.61	16.19	12.33
offline	hitProxy	0.104	0.105	0.077	0.098 (+27%)
live (this run)	hit rate	12.3%	0.6%	9.2%	0.4%

The ruler said HeadOn is equal-or-better at 300+; live it is 20×/23× worse. The ruler is a per-tick, open-loop replay of a fixed enemy track: a no-lead gun's aim error is scored against the enemy's true future position on that same pre-recorded dodge, which is not the distribution a different bullet induces. Live, the bullet changes the dodge, and the static gun simply does not lead the surfer. This is precisely the open-loop/live gap the ruler cannot see. The offline aim-error ruler is not a valid predictor of the live HeadOn-vs-Pattern question — do not use it to rank no-lead guns at range.

Caveats and what is inferred

• [MEASURED] All numbers above, from this session's server-side events sidecar; one frozen binary; liveness OK for both arms; wins == firstPlaces 15/15 both arms.
• [INFERRED] The rack-membership change also removes a gun's 4 virtual bullets/tick from the shared order-sensitive ring (docs/gun_rack_analysis.md §1.1). Both arms are single-gun racks and the effect size (0/105 rounds, ~7× MDE) is far too large for ring-order to explain.
• [MEASURED] One adversary (the real DrussGT jar). The 70-run offline corpus this ruler was built on is the same live capture set, so the two disagree on the same adversary — the disagreement is the open-loop/live gap, not a matchup difference.
• Reproduce: tools/ab/ab_run.sh --arms tools/ab/arms_headon.txt --runs 15 --outdir /tmp/ab_headon --conc 8 --rounds 7; python3 tools/ab/ab_analyze.py /tmp/ab_headon --reference control; python3 tools/ab/ab_range_bands.py /tmp/ab_headon --reference control.