====================================================================================================
MECHANISM CHECK — did the arm actually move differently?
session /tmp/ab/heatshift  arms old, pillaoff, tau15, tau3, tau5, tau9  reference old
box = 144x144 px centred on the arena centre (x 328-472, y 228-372)
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PER-ARM MECHANISM (mean of the per-round values, then over runs)
arm        runs    box%  dist px    p10    med    p90   enB<=100px%   enBmin px
-------------------------------------------------------------------------------
old          10    0.09    469.3    433    465    511         27.99       136.1
pillaoff     10    2.37    443.5    396    446    490         29.10       132.8
tau15        10    4.68    500.1    467    502    533         25.57       141.4
tau3         10   26.12    439.4    406    440    471         30.86       134.8
tau5         10   21.30    447.8    410    451    484         30.60       134.1
tau9         10   10.40    481.1    440    482    512         28.31       137.8

DISTANCE-TO-ENEMY BANDS (fraction of ticks, mean over rounds/runs, %)
arm            0-100   100-200   200-300   300-400      400+
------------------------------------------------------------
old             0.11      0.51      2.15     14.24     82.99
pillaoff        0.15      0.95      3.33     23.46     72.12
tau15           0.18      0.56      1.64      9.47     88.15
tau3            0.18      0.89      3.73     24.80     70.39
tau5            0.23      0.84      3.80     21.20     73.93
tau9            0.21      0.71      2.04     11.53     85.51

ENEMY-BULLET PROXIMITY (nearest LIVE ENEMY bullet; our own bullets are excluded because a bullet is born at its own tank, so 'any bullet' is dominated by our just-fired shot)
arm          <=50px  <=100px  <=150px   min px   enemy%
-------------------------------------------------------
old            4.76    27.99    62.48    136.1    97.04
pillaoff       4.97    29.10    64.98    132.8    97.25
tau15          4.12    25.57    58.43    141.4    97.06
tau3           6.19    30.86    61.39    134.8    97.03
tau5           5.88    30.60    62.59    134.1    97.31
tau9           4.99    28.31    60.75    137.8    97.45

ANY-BULLET PROXIMITY (per the task text: nearest live bullet, ours included; context only)
arm          <=50px  <=100px  <=150px   min px     any%
-------------------------------------------------------
old           24.96    56.38    83.24     92.4    98.17
pillaoff      25.33    57.33    84.58     90.5    98.01
tau15         24.39    54.95    81.71     94.3    98.04
tau3          26.25    57.89    82.66     90.7    97.65
tau5          25.88    57.83    83.50     90.6    97.84
tau9          25.05    56.42    82.41     92.7    98.05

PER-RUN MECHANISM vs `old` (two-sided permutation on per-run means; exact when C(n,na)<=2e7)
metric                   arm            delta         p method             MDE
------------------------------------------------------------------------------
central-box occupancy    pillaoff       +2.29    0.0000 exact            0.11%
central-box occupancy    tau15          +4.60    0.0000 exact            0.11%
central-box occupancy    tau3          +26.04    0.0000 exact            0.11%
central-box occupancy    tau5          +21.21    0.0000 exact            0.11%
central-box occupancy    tau9          +10.31    0.0000 exact            0.11%
mean dist to enemy       pillaoff      -25.74    0.0002 exact           20.81px
mean dist to enemy       tau15         +30.82    0.0001 exact           20.81px
mean dist to enemy       tau3          -29.90    0.0004 exact           20.81px
mean dist to enemy       tau5          -21.44    0.0014 exact           20.81px
mean dist to enemy       tau9          +11.82    0.0813 exact           20.81px
ticks enemy bullet<=100px pillaoff       +1.11    0.1381 exact            1.74%
ticks enemy bullet<=100px tau15          -2.43    0.0001 exact            1.74%
ticks enemy bullet<=100px tau3           +2.87    0.0014 exact            1.74%
ticks enemy bullet<=100px tau5           +2.61    0.0005 exact            1.74%
ticks enemy bullet<=100px tau9           +0.32    0.6066 exact            1.74%
mean dist nearest enemy bullet pillaoff       -3.29    0.0155 exact            3.03px
mean dist nearest enemy bullet tau15          +5.28    0.0000 exact            3.03px
mean dist nearest enemy bullet tau3           -1.24    0.3106 exact            3.03px
mean dist nearest enemy bullet tau5           -2.01    0.1130 exact            3.03px
mean dist nearest enemy bullet tau9           +1.68    0.1133 exact            3.03px
ticks ANY bullet<=100px  pillaoff       +0.95    0.0394 exact            1.39%
ticks ANY bullet<=100px  tau15          -1.43    0.0040 exact            1.39%
ticks ANY bullet<=100px  tau3           +1.51    0.0228 exact            1.39%
ticks ANY bullet<=100px  tau5           +1.45    0.0147 exact            1.39%
ticks ANY bullet<=100px  tau9           +0.04    0.9388 exact            1.39%
