# Gun Rack Summary — TL;DR

**Date:** 2026-09-21 · **Bot:** ModularBot (13 active guns + 1 disabled TM gate)
**Shipped config:** metric `path`, selector `relative`.
**Ground truth:** server-side real hit rate (events sidecar), per-run, with an
explicit overlap test. Scores are not used — they swing by a couple of hundred
points per run.

**Boss:** the unmodified DrussGT jar through `tools/robocode_shim/`.
**Headline (13 runs vs DrussGT, 3,612 server-side shots): 6.95% real hit rate,
251 dmg/run.** The **same binary** on a 15-run set measures **6.18%** (events
6.16%), so always read a rate with its run count.

**The one thing to know:** *virtual hit rate is a poor ranker, not a reliable
proxy for real hit rate.* Its Spearman correlation with real hit rate is weak
and **sign-unstable** across run sets — **−0.374** over 13 runs, but **+0.335**
over a 15-run paired baseline (same 13 guns, different but equally defensible
aggregation) and +0.522 on the 5-run `relative+path` set — i.e. near zero on
average, **not** reliably anti-correlated. An earlier version of this report
overstated it as an inversion; the later 15-run measurement refuted that. 16
candidate ranking rules all failed to beat the shipped config; what works is the
selector's floor/tie hedging (removing the floor: 5.08% / 175 dmg vs 6.95% /
251 dmg). Detail: [`gun_rack_analysis.md`](gun_rack_analysis.md).

## Verdict table

| Verdict | Gun | Real % | Virtual % |
|---|---|---:|---:|
| **KEEP** | Linear | 10.7 | 10.2 |
| **KEEP** | Circular | 9.9 | 11.9 |
| **KEEP** | KNN | 9.0 | 7.5 |
| **KEEP** | Pattern | 8.6 | 12.0 |
| **KEEP** | Accel | 7.3 | 12.1 |
| **KEEP** | AvgLead | 7.0 | 12.3 |
| MARGINAL | GuessFactor | 6.9 | 10.3 |
| MARGINAL | DecayGF | 6.4 | 9.2 |
| MARGINAL | WallBounce | 6.2 | 12.9 |
| MARGINAL | StopShot | 6.1 | 12.6 |
| **KEEP** (below overall; pruning no help) | Tsetlin | 5.8 | 12.9 |
| **KEEP** (below overall; pruning no help) | Displace | 5.3 | 12.3 |
| **FLOOR — KEEP** | HeadOn | 5.2 | 8.6 |
| DISABLED | TMSelect | — | — |

HeadOn is lowest but **must stay**: it is the floor fallback, and disabling the
floor measurably hurt (5.08% / 175 dmg).

**Keep the full rack.** Tsetlin and Displace are below overall, but removing
them was **tested**: 15 paired runs per variant gave 6.18% → 5.76% (Tsetlin
disabled) and 5.46% (Tsetlin+Displace disabled), with fully overlapping per-run
distributions and paired permutation p = 0.57 / 0.21. Being below overall does
**not** justify removal.

## Top actions

1. **Stop trusting the virtual metric as a ranker.** It is a poor ranker —
   weak, sign-unstable across run sets (−0.374 over 13 runs vs +0.335 over 15),
   and near zero on average, **not** reliably anti-correlated. The selector
   survives on its floor/tie hedge, not on its ordering.
2. **Acceptance test is fixed, not flaky.** The old 11/12 was a real replay
   bug (the replay spawned disabled gun 13, and the shared ring is
   order-sensitive, so it permuted every other gun's resolution order). It now
   mirrors the live rack: 5/5 runs byte-identical 12/12 with the death boundary
   included.
3. **Get a second adversary.** Every per-gun verdict rests on one wave surfer;
   the KEEP/BELOW boundaries are matchup-specific and per-gun N is small
   (47–898 shots).
4. **Keep Tsetlin and Displace (pruning tested).** Both are below overall on
   small N, but disabling Tsetlin (15 paired runs: 6.18% → 5.76%) and
   Tsetlin+Displace (→ 5.46%) was neutral-to-slightly-negative; keep the full
   rack. Tsetlin now learns (clauses 714→13.8 literals) but is not competitive —
   the regression head is a follow-up, not grounds for removal.
5. **Do not re-enable TMSelect** until the gate-margin/label problem is fixed;
   it cost 7.47% → 5.59% despite showing real energy structure in its clauses.
6. **Real-hit-rate-driven selection is not viable yet** — unselected guns get
   near-zero shots, so it needs forced exploration + shrinkage + thousands of
   shots per gun.
7. **Selector tie-break is now seeded.** It had been effectively deterministic
   (`randomize()` reached only incidentally via the Tsetlin constructor); now an
   explicit startup seed plus a `GUN_SELECTOR_SEED` override makes seeded runs
   reproducible and unseeded runs vary.
8. **The arrival-accuracy tie-band does not beat the shipped band** (7 runs x 7
   rounds/arm vs DrussGT, one frozen binary): path-ranking + point-narrowing
   7.08% vs shipped 7.17% (overlapping, p = 0.88), while the no-randomness
   control (`GUN_SELECTOR_TIEBREAK=commit`) is significantly worse at 4.44%
   (p = 0.0012). The `TIE`/`FLOOR`/`WINDOW` sweep is also nominally worse at
   every setting. **Shipped selector unchanged**; `GUN_SELECTOR_TIEBREAK`
   defaults to `off`. Detail: [`gun_rack_analysis.md`](gun_rack_analysis.md) §6.8.