SirRoboGarage/docs/selector_negative_value.md

The gun selector is currently NEGATIVE value

Measured. The best single gun beats the full rack, and not by a little.

arm	runs	shots	hits	real %	dmg/run	per-run range	exact two-sided p vs full
full (shipped rack)	7	3898	270	6.93	159	2.54–10.37	—
onlyPattern	7	4582	494	10.78	287	9.14–11.85	0.0012
onlyKNN	7	4033	207	5.13	119	4.15–6.47	0.1340
onlyLinear	7	3215	105	3.27	65	1.85–4.69	0.0082
onlyGF	7	3193	72	2.25	45	1.52–3.47	0.0012

Firing Pattern alone: +3.85 pp pooled hit rate, +80% damage per run, p = 0.0012. It also fires MORE shots (4582 vs 3898), so it dominates on rate and volume.

This is not "any single gun wins" — full beats onlyLinear, onlyGF and onlyKNN. It is specifically "Pattern alone beats the rack".

Follow-up: a small rack of GOOD guns STILL loses to Pattern alone

The obvious objection to the result above — "the rack is bloated, so of course it loses; prune it" — was tested directly. Same protocol (one frozen binary, rack knobs only, real DrussGT, server-side real hit rate), 6 arms × 7 runs × 7 rounds. lean8/lean6 are the offline audit's recommended racks, with the selector ACTIVE; onlyPattern is the no-selection control.

arm	guns (selector active?)	runs	shots	hits	real %	dmg/run	per-run range	exact two-sided p vs onlyPattern
onlyPattern (control)	Pattern, NO selection	7	4325	448	10.36	264	8.96–11.47	—
lean8	HeadOn, Linear, Circular, Accel, Pattern, GF, KNN, WallBounce	7	3711	234	6.31	146	2.64–12.99	0.0169
lean6	lean8 − HeadOn	7	4113	363	8.83	212	7.35–10.87	0.0262
pairPC	Pattern + Circular	7	3862	318	8.23	185	3.36–11.64	0.0460
pairPK	Pattern + KNN	7	4571	448	9.80	264	7.90–12.76	0.3998
pairPL	Pattern + Linear	7	4109	338	8.23	200	6.14–9.90	0.0035

No small rack beats Pattern alone. Every selector-active arm is worse or (in one case) statistically indistinguishable:

• lean8 is far worse — 6.31% vs 10.36%, p = 0.0169. Pruning to the audit's recommended good guns did NOT rescue the selector.
• lean6 (HeadOn removed) is still worse — 8.83% vs 10.36%, p = 0.0262. Removing the single most-over-selected gun helps (+2.5 pp over lean8) but still does not beat no-selection.
• pairPK is the only near-tie — 9.80% vs 10.36%, p = 0.3998, identical dmg/run. It ties only because the selector happens to pick Pattern 86.4% of the time on a 2-gun rack; it does not beat Pattern.

Verdict: the selector is negative value on a good rack too — DISABLE it

lean6 and lean8 (selector active) are both significantly WORSE than Pattern alone. This contradicts the standing directive to keep the virtual-fitness selection mechanism, so it is stated plainly: the selection apparatus should be disabled (TR_RACK_<every gun but PATTERN>=off) pending a better fitness signal. Keeping it costs ~1.5–4 pp of real hit rate on a good rack.

Why the pruned racks still lose: the same mis-ranking, visible in the mix

The selected-gun mix (liveness proof) shows the virtual signal still over-selects the wrong guns:

• lean8: HeadOn 46.2% of ticks → only 2.0% real (34/1670); WallBounce 21.0% → 6.5% real (35/540); Pattern only 14.4% → 12.6% real (65/514). HeadOn and WallBounce crowd out the best gun.
• lean6 (HeadOn gone): Pattern 29.2% → 10.4% real (127/1216) — the best real gun — while KNN 25.3% → 8.1%, Linear 15.2% → 8.0%, Accel 13.8% → 8.7%. The rack is still diluted.
• pairPL: the selector gives Linear 57.7% of ticks → 6.0% real (103/1712), and Pattern only 42.3% → 11.1% real. Over-selecting Linear is why pairPL is the worst 2-gun arm (p = 0.0035).

The failure is not "the rack is too big". It is that the virtual fitness signal ranks the wrong guns first, on a big rack and on a small one alike.

Ship recommendation

onlyPattern — Pattern alone, selector bypassed. Measured: 10.36% real hit rate, 264 damage/run (vs lean8 6.31%/146 and full 6.93%/159). This replicates the original finding (10.78%/287).

Method note: one frozen binary built from clean e0666a5 via git archive (other agents had common_libs/guns/* dirty and have since committed further changes; this build predates them), sha256 df8d4f2e…. 6 arms × 7 runs × 7 rounds, 8 concurrent bridge battles. Liveness verified for every arm from gun_stats.jsonl; the [rack] active=… line confirmed each arm's membership at process start.

Method

One frozen binary built from clean HEAD via git archive (other agents had common_libs/guns/* dirty), sha256 f02481d8…. Arms selected with the rack knobs only (TR_RACK_<GUN>=off), no source edits. 5 arms × 7 runs × 7 rounds, 8 concurrent bridge battles, real DrussGT, judged ONLY on server-side real hit rate from the events sidecar. Exact two-sided permutation test on per-run rates (C(14,7)=3432 splits). Each arm's liveness verified from the selected-gun mix.

Harness preserved at tools/ab/which_gun_*.sh and tools/ab/which_gun_analyze.py.

Why: the virtual fitness signal mis-ranks guns vs real outcomes

From the full arm's own selection mix and per-gun real rates:

• HeadOn is massively over-selected — 31.4% of ticks, the most real shots (1070), but only 4.5% real. It alone drags the rack down.
• Pattern has the best virtual rank and near-best real rate (11.9%, real rank 2), yet is selected only 22.6% of the time.
• Linear's apparent strength was SELECTION BIAS. Conditional on being selected it looked like 15.2% (n=33); its unconditional rate (onlyLinear) is 3.27%. Every earlier per-gun "real rate" in this repo is conditional on selection and is therefore confounded — this experiment is the clean measurement.

What this does NOT yet settle

• One adversary. Everything here is vs DrussGT. Pattern should be re-checked against other bots before it becomes the default on the strength of this alone. (Supporting evidence: an offline audit found Pattern is the only gun competitive in every distance/speed bucket.)
• Whether a SMALL good rack beats Pattern alone — SETTLED (follow-up above): NO. A 6-arm follow-up (lean8, lean6, pairPC, pairPK, pairPL) found every selector-active rack worse or tied; lean6 8.83% and lean8 6.31% both lose to Pattern alone 10.36% (p = 0.026 / 0.017). The selector is negative value on a good rack too.
• The user's directive was to KEEP the virtual-fitness selection mechanism — now directly tested. The follow-up tested the selector on small, good racks instead of assuming either answer; it lost there too, so the directive conflicts with the evidence and disabling is recommended pending a better signal.

Prior context: three failed selection-side attempts

attempt	result
hysteresis (commit to incumbent)	7.02% → 5.10%, p=0.002
commitment (remove the random draw)	7.17% → 4.44%, p=0.0012
arrival-accuracy tie-break (rank by path, narrow by point)	7.08%, p=0.88 — null

So the per-tick random draw is load-bearing on three independent measurements, and no attempt to "smarten" the tied band has helped. This experiment shows the problem is one level up: which guns are in the rack, and the fact that the virtual signal ranks them wrongly.