From b0654d18eb80d5da48b657a45c4498d1d0f8bf48 Mon Sep 17 00:00:00 2001
From: Davide Cappellini <signorsasso@gmail.com>
Date: Tue, 22 Sep 2026 08:21:49 +0200
Subject: [PATCH] TM verdict, settled: it loses LIVE and sits at/below its
 majority class - (c)

The user pushed back on "the TM can't be your best 1v1 gun", correctly, because two
decisive tests had never been run. Both are now run and they agree.

TASK 1 - THE GF HEAD vs ITS MAJORITY-CLASS BASELINE (offline, n=1,751,067):
  label histogram [254286, 284578, 678879, 297055, 236269]
  majority class = 2 (the CENTRE bucket) = 38.77%
  RAW head accuracy = 36.69%  ->  margin **-2.08 pp, BELOW majority**
  GATED head accuracy = 40.37% vs 38.75% majority -> +1.62 pp, BUT it predicts the
  majority class on 62.4% of ticks and its minority recall is 13.6% / 12.9% - a
  base-rate predictor wearing a classifier's clothes.
  Shuffled control sits at its own majority (20.04% vs 20.12%), confirming chance.
**THE OLD "46% vs 20% CHANCE" FIGURE I QUOTED WAS WRONG ON TWO COUNTS:** the
baseline is 38.8%, not 20%, and the 46% predated the deferred-label fix. Against
the correct baseline the head is BELOW it.

TASK 2 - THE FIRST-EVER LIVE A/B OF THE TM GUN (7 runs x 7 rounds per arm, one
frozen binary from git archive HEAD = eb74f9b2, sha256 cb66d66b..., real DrussGT,
every arm forced alone with TR_RACK_<GUN>=both and all 14 others off, liveness
confirmed per run):
  arm                     shots   real %   dmg/run   round wins
  onlyPattern              4610   10.74%     285      25/49
  onlyTMPATTERN (radial)   3374    3.50%      71       0/49
  onlyLinear               3218    3.23%      61       0/49
  Pattern vs TM:  +7.22 pp / +213.7 dmg, exact p=0.0006
  TM vs Linear:   +0.30 pp, p=0.659  (dmg p=0.438)
**The TM is statistically INDISTINGUISHABLE from its own Linear base live.** So it
is not "the TM works and we are aiming it wrong".

DIRECT ANSWER: **(c) It loses live AND sits at/below majority - the target carries
no learnable signal beyond the base rate, and that is the reason.** The reason is
not the machine, not the knobs, and not the application alone: the thing it was
asked to predict is dominated by the modal answer.

This closes the TM-as-gun thread. If a TM is wanted in the bot, a firing gate or a
movement decision is a better fit for a boolean-rule classifier than an aim point -
that is untested and is a different project.

A LIVE GF-MODE ARM WAS NOT RUN (stated as unmeasured): the task pinned one frozen
HEAD binary and HEAD registers the TM gun as radial only; Task 1 already makes GF
the unpromising candidate.

HARNESS FIX WORTH KEEPING: `tools/ab/which_gun_arm_env.sh` left the TARGET gun
unset, so with the now-Pattern-only default it silently fell back to the FULL rack
- an arm could appear to test a single gun while actually running the whole rack.
It now emits `TR_RACK_<GUN>=both` for the target and `=off` for all 14 others.
(Earlier which-gun results are unaffected: they ran before the Pattern-only default,
or - as in the melee/1v1 campaign - set the explicit `=both` themselves.)

tm_pattern.nim gains a per-class confusion matrix (warm samples only) to support the
majority baseline; no behaviour change. Adds Round 4 to
tm_pattern_sweep_results.md with both tasks and the interpretation rule.
---
 common_libs/guns/tm_pattern.nim               |  10 +
 common_libs/tests/sweep_tm_pattern.nim        |  47 ++++
 common_libs/tests/tm_pattern_sweep_results.md | 205 ++++++++++++++++++
 tools/ab/which_gun_arm_env.sh                 |  28 ++-
 tools/ab/which_gun_run_one.sh                 |   2 +-
 5 files changed, 281 insertions(+), 11 deletions(-)

diff --git a/common_libs/guns/tm_pattern.nim b/common_libs/guns/tm_pattern.nim
index e3ba0b4..2581d93 100644
--- a/common_libs/guns/tm_pattern.nim
+++ b/common_libs/guns/tm_pattern.nim
@@ -188,6 +188,14 @@ type
     radOffsetN*: int
     classCorrect*: int   ## warm predictions whose class matched the eventual label
     classTotal*:   int   ## warm predictions with a resolvable label
+    ## Per-class confusion matrix for the GF head, indexed [true label][predicted
+    ## class], counted over WARM predictions only (the same samples `classTotal`
+    ## scores). This is what makes the majority-class baseline and per-class
+    ## precision/recall measurable. Row sums = the warm label histogram; the
+    ## diagonal sum = classCorrect.
+    confusion*: array[TM_CLASSES, array[TM_CLASSES, int]]
+    ## Same for the radial head.
+    radConfusion*: array[TM_CLASSES, array[TM_CLASSES, int]]
     lastChosen*: int
     shuffleLabels*: bool  ## control: replace the computed GF label with a random class
     forceBase*: bool      ## measurement: ignore the TM, emit the pure LinearGun base
@@ -504,6 +512,7 @@ proc tmResolveTrace(g: var TmPatternGun, t: TmPatternTrace, power: float) =
   if t.warm:
     inc g.classTotal
     if winner == t.chosen: inc g.classCorrect
+    inc g.confusion[winner][t.chosen]
 
   # Radial label: enemy radius at the base arrival tick minus the base fire
   # distance. Independent of our own aim, so it is a clean target.
@@ -517,6 +526,7 @@ proc tmResolveTrace(g: var TmPatternGun, t: TmPatternTrace, power: float) =
   if t.warm:
     inc g.radTotal
     if radWinner == t.radChosen: inc g.radCorrect
+    inc g.radConfusion[radWinner][t.radChosen]
 
   # Reversal label: net heading turn over the flight, opposite to the direction
   # the enemy was turning at fire time.
diff --git a/common_libs/tests/sweep_tm_pattern.nim b/common_libs/tests/sweep_tm_pattern.nim
index 4cbacb6..f01608a 100644
--- a/common_libs/tests/sweep_tm_pattern.nim
+++ b/common_libs/tests/sweep_tm_pattern.nim
@@ -45,6 +45,8 @@ type
     labHist, choHist: array[TM_CLASSES, int]
     classCorrect, classTotal: int
     radCorrect, radTotal, revCorrect, revTotal: int
+    confusion: array[TM_CLASSES, array[TM_CLASSES, int]]
+    radConfusion: array[TM_CLASSES, array[TM_CLASSES, int]]
 
   Adapt = object
     h100, n100, h300, n300, hall, nall, f100, m100: int
@@ -103,6 +105,9 @@ proc addAdapt(dst: var Adapt, src: Adapt) =
   for c in 0..<TM_CLASSES:
     dst.st.labHist[c] += src.st.labHist[c]
     dst.st.choHist[c] += src.st.choHist[c]
+    for p in 0..<TM_CLASSES:
+      dst.st.confusion[c][p] += src.st.confusion[c][p]
+      dst.st.radConfusion[c][p] += src.st.radConfusion[c][p]
 
 proc replayRound(states: seq[WorldState], lastSeen: seq[int], enemyId, baseTick: int,
                  driver: GunDriver, metric: BulletMetric,
@@ -158,6 +163,9 @@ proc replayRound(states: seq[WorldState], lastSeen: seq[int], enemyId, baseTick:
   for c in 0..<TM_CLASSES:
     res.st.labHist[c] = after.labHist[c] - obsBefore.labHist[c]
     res.st.choHist[c] = after.choHist[c] - obsBefore.choHist[c]
+    for p in 0..<TM_CLASSES:
+      res.st.confusion[c][p] = after.confusion[c][p] - obsBefore.confusion[c][p]
+      res.st.radConfusion[c][p] = after.radConfusion[c][p] - obsBefore.radConfusion[c][p]
   result = res
 
 proc replayFixture(fx: Fixture, path: string, driver: GunDriver, metric: BulletMetric,
@@ -209,6 +217,8 @@ proc tmpatStats(g: ref TmPatternGun): GunStats =
   result.choHist = g[].chosenHist
   result.classCorrect = g[].classCorrect
   result.classTotal = g[].classTotal
+  result.confusion = g[].confusion
+  result.radConfusion = g[].radConfusion
   result.radCorrect = g[].radCorrect
   result.radTotal = g[].radTotal
   result.revCorrect = g[].revCorrect
@@ -252,6 +262,35 @@ proc signTestP(wins, n: int): float =
   for k in 0..lo: s += binomPmf(k, n)
   min(1.0, 2.0 * s)
 
+proc printConfusion(variant: string, cm: array[TM_CLASSES, array[TM_CLASSES, int]]) =
+  ## Task 1 deliverable: majority-class baseline vs online accuracy on the SAME
+  ## (warm) samples, plus per-class precision/recall. `cm[true][pred]`.
+  var total = 0
+  var diag = 0
+  var rowSum: array[TM_CLASSES, int]
+  var colSum: array[TM_CLASSES, int]
+  for c in 0..<TM_CLASSES:
+    for p in 0..<TM_CLASSES:
+      total += cm[c][p]
+      if c == p: diag += cm[c][p]
+      rowSum[c] += cm[c][p]
+      colSum[p] += cm[c][p]
+  var maj = 0
+  for c in 1..<TM_CLASSES:
+    if rowSum[c] > rowSum[maj]: maj = c
+  let majShare = if total > 0: rowSum[maj].float / total.float else: 0.0
+  let acc = if total > 0: diag.float / total.float else: 0.0
+  var hs = ""
+  for c in 0..<TM_CLASSES: hs.add &"{rowSum[c]},"
+  echo &"# {variant}: warmTotal={total} warmLabelHist=[{hs}] majority=class{maj} " &
+       &"majShare={majShare*100:.1f}% acc={diag}/{total}={acc*100:.1f}% " &
+       &"margin={((acc-majShare)*100):+.1f}pp"
+  for c in 0..<TM_CLASSES:
+    let rec = if rowSum[c] > 0: cm[c][c].float / rowSum[c].float else: 0.0
+    let prec = if colSum[c] > 0: cm[c][c].float / colSum[c].float else: 0.0
+    echo &"#   class{c}: trueN={rowSum[c]} predN={colSum[c]} TP={cm[c][c]} " &
+         &"recall={rec*100:.1f}% precision={prec*100:.1f}%"
+
 proc main() =
   var nSeeds = 3
   var set = "real"
@@ -358,6 +397,14 @@ proc main() =
         for c in 0..<TM_CLASSES: rdl.add &"{radLabTab[variantName(v)][c]},"
         echo &"#   label hist {variantName(v)}: radial=[{rdl}] rev=[{rl}]"
 
+  # ── TASK 1: majority-class baseline vs accuracy + per-class P/R ──
+  echo "\n# ── GF head majority-class test (warm samples only) ──"
+  for v in [vTmpat, vTmpatShuf]:
+    if v in variants: printConfusion(variantName(v), pooled[variantName(v)].st.confusion)
+  echo "\n# ── radial head confusion (context) ──"
+  for v in [vTmpatRad, vTmpatRadShuf]:
+    if v in variants: printConfusion(variantName(v), pooled[variantName(v)].st.radConfusion)
+
   # ── per-run distributions (a "run" = one fixture × one seed) ──
   # Linear is deterministic: replicate its one row per fixture across seeds so a
   # paired comparison against a stochastic variant has a partner per run.
diff --git a/common_libs/tests/tm_pattern_sweep_results.md b/common_libs/tests/tm_pattern_sweep_results.md
index fa10474..02c3f21 100644
--- a/common_libs/tests/tm_pattern_sweep_results.md
+++ b/common_libs/tests/tm_pattern_sweep_results.md
@@ -590,3 +590,208 @@ nim c --path:common_libs -d:release -o:/tmp/sweep_radial_offset \
 # smoke: --seeds=1
 ```
 
+
+---
+
+# ROUND 4 — THE TWO DECISIVE TESTS: the majority-class baseline, and the LIVE A/B
+
+Date: 2026-09-22. Author: background worker (executor-heavy). Artifacts: the
+`confusion`/`radConfusion` instrumentation in `common_libs/guns/tm_pattern.nim`
+(+`GunStats.confusion` in `common_libs/tests/sweep_tm_pattern.nim`); the live A/B
+table below. Raw outputs: `/tmp/tmjob/raw_path_s1.txt`, `/tmp/tmjob/gated_path_s1.txt`,
+`/tmp/tmjob/gated_path_s3.txt`, `/tmp/tmjob/whichgun/analyze_out.txt`,
+`/tmp/tmjob/whichgun/analyze_tm_out.txt`. Do NOT commit.
+
+The two questions the earlier rounds never answered honestly:
+1. Is the GF-target head actually beating the MAJORITY-CLASS baseline, or only
+   the 20% "chance" figure that was never the right comparison?
+2. Has the TM gun ever been A/B'd LIVE against Pattern? (It had not — only
+   offline on bmPath/bmPoint, and the offline metric is a poor live predictor.)
+
+## TASK 1 — GF head vs its majority class (MEASURED)
+
+Method: `sweep_tm_pattern.nim`, committed DrussGT fixtures
+(`--set=real`, 6 fixtures / 77 rounds), position-ring labels, seeds=1, bmPath.
+The new `confusion[true][pred]` matrix is counted over the SAME warm samples the
+`classCorrect/classTotal` accuracy already scores, so the baseline is on the same
+samples. `warmLabelHist` = row sums; `accuracy` = diagonal / total; majority =
+`max(warmLabelHist)/total`. The shuffled control randomises only the claimed
+label. Configs: RAW = the default hard argmax (`TM_CONF_MARGIN=0.0`); GATED =
+round-1/2 "best" (`TM_CONF_MARGIN=0.25`, `TM_SHRINK=0.5`).
+
+### RAW head (default hard argmax) — seeds=1, n=1,751,067 warm predictions
+
+| | |
+|---|---|
+| warm label histogram `[c0..c4]` | `[254286, 284578, 678879, 297055, 236269]` |
+| majority class | **class 2 (centre)** |
+| majority share | **38.77%** |
+| head accuracy | **36.69%** (642473/1751067) |
+| **margin over majority** | **−2.08 pp (AT/BELOW)** |
+| shuffled control | 20.04% vs 20.12% majority → chance (margin −0.08 pp) |
+
+Per-class precision/recall (RAW):
+
+| class | true N | pred N | TP | recall | precision |
+|---|---|---|---|---|---|
+| 0 | 254286 | 387266 | 107056 | 42.1% | 27.6% |
+| 1 | 284578 | 214589 | 63224 | 22.2% | 29.5% |
+| 2 | 678879 | 692044 | 336818 | 49.6% | 48.7% |
+| 3 | 297055 | 215960 | 57809 | 19.5% | 26.8% |
+| 4 | 236269 | 241208 | 77566 | 32.8% | 32.2% |
+
+### GATED head (margin=0.25, shrink=0.5) — seeds=1, n=1,751,844
+
+| | |
+|---|---|
+| warm label histogram | `[255146, 284332, 678780, 297017, 236569]` |
+| majority | class 2, **38.75%** |
+| accuracy | **40.37%** (707199/1751844) |
+| **margin over majority** | **+1.62 pp** |
+| shuffled control | 20.24% vs 20.10% majority → chance (margin +0.13 pp) |
+
+GATED per-class precision/recall:
+
+| class | true N | pred N | TP | recall | precision |
+|---|---|---|---|---|---|
+| 0 | 255146 | 224606 | 77412 | 30.3% | 34.5% |
+| 1 | 284332 | 124841 | 38752 | **13.6%** | 31.0% |
+| 2 | 678780 | 1092616 | 484804 | 71.4% | 44.4% |
+| 3 | 297017 | 128494 | 38298 | **12.9%** | 29.8% |
+| 4 | 236569 | 181287 | 67933 | 28.7% | 37.5% |
+
+seeds=3 GATED (n=5,254,780): accuracy **40.1%** vs **38.8%** majority
+(+1.4 pp); minority recall class 1 **13.9%**, class 3 **13.0%**. The shuffled
+control seeds=3 sits at 20.1% vs 20.1% majority.
+
+**What the gate is doing (MEASURED):** the gated head predicts the majority class
+on 1,092,616 / 1,751,844 = **62.4%** of warm ticks (vs 38.8% base rate); the
+shuffled gated control does the same thing (69.4% class-2), which is why its
+"accuracy" is also ~its majority. The real head's +1.6 pp over majority is
+statistically distinguishable at this n (SE ≈ 0.037 pp) but comes almost
+entirely from re-allocating predictions toward the centre while recovering a
+little mass on classes 0/4; recall on classes 1 and 3 is near-trivial.
+
+**INTERPRETATION RULE (stated explicitly, and applied):** if the head is at or
+below the majority baseline, the TM is NOT extracting conditional information
+beyond the base rate, and no amount of engineering fixes that. If it is
+meaningfully above majority AND has non-trivial minority-class recall, the TM IS
+learning and the problem is the application, not the machine.
+
+**Task 1 verdict (MEASURED):** the RAW classifier — the head's actual output —
+is **2.1 pp BELOW its majority class**. Only a deliberately gated/abstaining
+config edges 1.4–1.6 pp above, by predicting the majority class 62% of the time,
+with minority-class recall of 13–14%. On the rule above this is **at/below the
+majority baseline** — the GF target carries essentially no learnable conditional
+signal beyond the base rate. The earlier "46.0% vs 20% chance" claim was
+misleading on two counts: the correct baseline is **38.8%** (not 20%), and the
+46% figure was measured on the pre-deferred-label-fix sample set (n≈1.26 M); with
+the deferred-label fix (n≈1.75 M, `labelMiss=0`, `traceMiss=0`) the unbiased raw
+head falls below majority. (Cause of the 46→36.7/40.4 change: INFERRED — the
+deferred-label fix added the previously-dropped short-aim samples; those samples
+are the ones the head gets wrong.)
+
+## TASK 2 — THE LIVE A/B (MEASURED)
+
+This is the first time the TM gun has ever been fought live against the shipped
+gun. The registered, committed candidate is `initTmRadialGun()` (TMPATTERN id 14,
+**radial** target mode) — that is the arm tested; a GF-mode live arm was not run
+because the task specifies ONE frozen HEAD binary and HEAD registers radial only
+(and Task 1 above makes GF the unpromising candidate).
+
+* **Frozen binary**: built from `git archive HEAD` → source commit
+  **eb74f9b2e39af70caa36c092e94f1ac5eca8b5e6**
+  ("Ram: finisher-only by default ..."), sha256
+  **cb66d66b3bf4c0d3a358ff20133c7e8455cda37e8236109ce32b0283c2fd01be**
+  (`/tmp/tmjob/ModularBot_frozen`). My working-tree instrumentation edits are NOT
+  in it (HEAD's `tm_pattern.nim` is radial-registered and untouched).
+* **Adversary**: real DrussGT via `tools/robocode_shim/run_bridge_battle.sh`.
+* **Arms**: `onlyPattern` (incumbent), `onlyTMPATTERN` (TM, radial), `onlyLinear`
+  (reference = the TM's own base). Every arm forced with `TR_RACK_<GUN>=both`
+  and **all 14 other guns `off`**, including TMPATTERN in the non-TM arms (the
+  repo `arm_env.sh` was fixed to emit `=both` explicitly so an arm can never fall
+  back to the FULL rack).
+* **7 runs × 7 rounds per arm, 7 concurrent**, distinct ports/output files.
+* **Liveness (MEASURED)**: the `[rack] mode=1v1 active=` line is exactly the
+  target gun in every run (`PATTERN` / `TMPATTERN` / `LINEAR`) and the
+  selected-gun mix is 100% that gun (Pattern 79401 sel, TMPattern 83478 sel,
+  Linear 80233 sel). TMPattern fired real bullets every run.
+
+### Live results — damage/run is PRIMARY
+
+| arm | runs | shots | hits | real % | **dmg/run** | **round wins** | mean round len | real % range | dmg range |
+|---|---|---|---|---|---|---|---|---|---|
+| **onlyPattern** | 7 | 4610 | 495 | **10.74%** | **285** | **25/49** | 1625 | 9.31–12.01 | 236–344 |
+| onlyTMPATTERN | 7 | 3374 | 118 | 3.50% | 71 | 0/49 | 1743 | 2.22–5.41 | 44–104 |
+| onlyLinear | 7 | 3218 | 104 | 3.23% | 61 | 0/49 | 1642 | 1.43–5.14 | 28–106 |
+
+Per-run values (`run: hits/shots rate, dmg, roundWins/7, meanTurn`):
+
+* `onlyPattern` — r1 `86/716 12.01% 344 4/7 1772`; r2 `67/620 10.81% 274 4/7 1481`;
+  r3 `60/534 11.24% 246 0/7 1314`; r4 `73/703 10.38% 292 7/7 1719`;
+  r5 `59/634 9.31% 236 0/7 1646`; r6 `74/695 10.65% 299 7/7 1692`;
+  r7 `76/708 10.73% 304 3/7 1753`.
+* `onlyTMPATTERN` — r1 `19/437 4.35% 76 0/7 1691`; r2 `14/489 2.86% 68 0/7 1837`;
+  r3 `21/490 4.29% 84 0/7 1805`; r4 `16/505 3.17% 73 0/7 1681`;
+  r5 `11/477 2.31% 50 0/7 1713`; r6 `11/495 2.22% 44 0/7 1723`;
+  r7 `26/481 5.41% 104 0/7 1747`.
+* `onlyLinear` — r1 `19/465 4.09% 76 0/7 1781`; r2 `7/491 1.43% 28 0/7 1674`;
+  r3 `25/486 5.14% 106 0/7 1837`; r4 `7/425 1.65% 34 0/7 1447`;
+  r5 `14/417 3.36% 56 0/7 1456`; r6 `17/454 3.74% 68 0/7 1638`;
+  r7 `15/480 3.12% 60 0/7 1664`.
+
+Exact two-sided permutation test on per-run values (7 vs 7, C(14,7)=3432 exact):
+
+| A vs B | metric | mean diff (A−B) | exact p |
+|---|---|---|---|
+| onlyPattern vs onlyTMPATTERN | hit-rate pp | **+7.22** | **0.0006** |
+| onlyPattern vs onlyTMPATTERN | dmg | **+213.7** | **0.0006** |
+| onlyPattern vs onlyLinear | hit-rate pp | +7.51 | 0.0006 |
+| onlyPattern vs onlyLinear | dmg | +223.9 | 0.0006 |
+| **onlyTMPATTERN vs onlyLinear** | hit-rate pp | **+0.30** | **0.6591** |
+| **onlyTMPATTERN vs onlyLinear** | dmg | **+10.1** | **0.4376** |
+
+**Task 2 verdict (MEASURED):** Pattern **decisively** beats the TM gun live —
+10.74% vs 3.50% hit rate, 285 vs 71 dmg/run, 25 vs **0** round wins of 49,
+p=0.0006 on both hit rate and damage, with **non-overlapping** per-run ranges
+(Pattern 9.31–12.01 vs TM 2.22–5.41). The TM gun is **statistically
+indistinguishable from its own Linear base** (p=0.66 hit rate, p=0.44 damage):
+the whole radial TM correction is a live no-op, exactly as Round 3 predicted for
+the structural-radial dead end. The TM gun cannot be the best 1v1 gun.
+
+## DIRECT ANSWER — can the TM gun be the best 1v1 gun?
+
+**(c) It loses live AND it sits at/below its majority class — the target carries
+no learnable conditional signal, and that is the reason.**
+
+* LIVE: the registered TM (radial) loses decisively to Pattern (3.50% vs 10.74%,
+  p=0.0006; 0 vs 25 round wins) and is no better than its own Linear base
+  (p=0.66). It was never the best gun live.
+* OFFLINE: the GF head at its honest (raw) readout is 2.1 pp BELOW the 38.8%
+  majority class; the gated config is only 1.4–1.6 pp above, by predicting the
+  majority 62% of the time and with 13–14% recall on the two minority classes the
+  correction would need. The radial head was already measured at/below majority
+  in Round 3 (56.2% vs 57.2%).
+* Therefore the TM machine is not the limiting factor in the sense "it learns and
+  we aim it wrong" (that would be (b)); the discrete GF/radial targets simply do
+  not contain conditional information beyond the base rate for these surfers, and
+  the live result agrees with the offline majority-class analysis.
+
+## MEASURED vs INFERRED (round 4)
+
+* **MEASURED**: the GF head confusion matrices, warm label histograms, majority
+  shares, accuracies, margins, per-class precision/recall, and the shuffled
+  controls (seeds=1 RAW+GATED, seeds=3 GATED); the fact that RAW is below
+  majority and GATED is +1.4–1.6 pp above by majority-class over-prediction.
+* **MEASURED**: the live table (shots, hits, real %, dmg/run, round wins, mean
+  round length, per-run ranges, exact permutation p vs onlyPattern and TM vs
+  Linear), the frozen-binary commit + sha256, and the per-arm `[rack] active=`
+  liveness lines.
+* **MEASURED**: `onlyTMPATTERN` and `onlyLinear` are indistinguishable live
+  (p=0.66/0.44) — the radial correction changes nothing in real physics.
+* **INFERRED**: that the drop from the old 46.0% to the current 36.7%/40.4% is
+  caused by the deferred-label fix enlarging the sample set (1.26 M → 1.75 M)
+  with the short-aim samples the head gets wrong; the current numbers are
+  measured, the causal attribution is not separately ablated.
+* **INFERRED (not measured)**: a live GF-mode arm — not run (one frozen HEAD
+  binary; HEAD registers radial only). Task 1 makes it the unpromising candidate.
diff --git a/tools/ab/which_gun_arm_env.sh b/tools/ab/which_gun_arm_env.sh
index af552a8..0a45299 100755
--- a/tools/ab/which_gun_arm_env.sh
+++ b/tools/ab/which_gun_arm_env.sh
@@ -1,13 +1,20 @@
-# emits `TR_RACK_<GUN>=off ...` for every gun NOT in the arm.
-# usage: arm_env.sh <full|onlyLinear|onlyPattern|onlyGF|onlyKNN|lean8|lean6|pairPC|pairPK|pairPL>
+# emits `TR_RACK_<GUN>=both` for the kept gun and `TR_RACK_<GUN>=off` for every
+# other gun, so the rack can never silently fall back to the FULL-rack
+# degradation when the target gun's `=both` was forgotten.
+# usage: arm_env.sh <full|onlyLinear|onlyPattern|onlyTMPATTERN|onlyGF|onlyKNN|lean8|lean6|pairPC|pairPK|pairPL>
 arm="$1"
-GUNS="HEADON LINEAR TSETLIN CIRCULAR GUESSFACTOR PATTERN WALLBOUNCE ACCEL STOPSHOT DISPLACE AVGLEAD DECAYGF KNN TMSELECT"
+GUNS="HEADON LINEAR TSETLIN CIRCULAR GUESSFACTOR PATTERN WALLBOUNCE ACCEL STOPSHOT DISPLACE AVGLEAD DECAYGF KNN TMSELECT TMPATTERN"
+if [ "$arm" = "full" ]; then
+  # Every gun `both` (the process default is onlyPattern, so this must be
+  # explicit).
+  keep="$GUNS"
+else
 case "$arm" in
-  full) keep="";;
-  onlyLinear)   keep="LINEAR";;
-  onlyPattern)  keep="PATTERN";;
-  onlyGF)       keep="GUESSFACTOR";;
-  onlyKNN)      keep="KNN";;
+  onlyLinear)    keep="LINEAR";;
+  onlyPattern)   keep="PATTERN";;
+  onlyTMPATTERN) keep="TMPATTERN";;
+  onlyGF)        keep="GUESSFACTOR";;
+  onlyKNN)       keep="KNN";;
   # ── small-good-rack follow-up ──────────────────────────────────────────────
   lean8)        keep="HEADON LINEAR CIRCULAR ACCEL PATTERN GUESSFACTOR KNN WALLBOUNCE";;
   lean6)        keep="LINEAR CIRCULAR ACCEL PATTERN GUESSFACTOR KNN";;
@@ -16,11 +23,12 @@ case "$arm" in
   pairPL)       keep="PATTERN LINEAR";;
   *) echo "unknown arm $arm" >&2; exit 1;;
 esac
+fi
 out=""
 for g in $GUNS; do
   case " $keep " in
-    *" $g "*) continue;;
+    *" $g "*) out="$out TR_RACK_${g}=both";;
+    *)        out="$out TR_RACK_${g}=off";;
   esac
-  out="$out TR_RACK_${g}=off"
 done
 echo "$out"
diff --git a/tools/ab/which_gun_run_one.sh b/tools/ab/which_gun_run_one.sh
index 275292d..f5a3c27 100755
--- a/tools/ab/which_gun_run_one.sh
+++ b/tools/ab/which_gun_run_one.sh
@@ -4,7 +4,7 @@
 set -u
 ARM="$1"; RUN="$2"; ROUNDS="${3:-7}"
 ROOT=/home/davide/Projects/SirRoboGarage
-OUT=/tmp/whichgun
+OUT="${WHICHGUN_OUT:-/tmp/whichgun}"
 BOTDIR="$OUT/drussgt_bots/${ARM}_${RUN}/DrussGT"
 mkdir -p "$BOTDIR" "$OUT/botlog"