SirRoboGarage/docs/env_reference.md

Environment variable reference

Every knob the bot reads. All are read ONCE at process start.

The bot is spawned by the server (or by the GUI if it starts its own server). So the variable must be set on that process, not in an unrelated terminal. Export it in the shell that launches the server/GUI.

An unset (or empty, or unparseable) value means the shipped default — a typo can never silently change behaviour, it warns on stderr and falls back.

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The ones you'll actually use live

variable	default	what it does
TR_MOVEMENT	tfil	movement engine: tfil (shipped) or tfil_ring (range-weighted variant)
TR_RACK_<GUN>	see below	move a gun in/out of the rack per mode
TR_POWER_POLICY	1	0 = uncapped control arm (today's behaviour without the energy policy)
TR_POWER_LOG	off	1 = log each power decision with its reason
TR_RAM_LOG	off	1 = log ram on/off with the reason
TR_MOVEMENT_LOG	off	1 = log movement band/class changes
TR_TMHORIZON_LOG	off	1 = let the horizon TM gun log its thinking per shot

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1. Gun rack — which gun(s) may be chosen

variable	default	what it does
TR_RACK_<GUN>	PATTERN=both, all others off	membership: both | 1v1 | melee | off
GUN_RACK_DISABLE	empty	comma-separated gun ids to remove entirely (older mechanism; the gun never even spawns virtual bullets)
GUN_STATS_PATH	/tmp/gun_stats.jsonl	where the per-round per-gun stats are written

<GUN> names: HEADON LINEAR TSETLIN CIRCULAR GUESSFACTOR PATTERN WALLBOUNCE ACCEL STOPSHOT DISPLACE AVGLEAD DECAYGF KNN TMSELECT TMPATTERN TMHORIZON.

The shipped default is Pattern only. To restore the full old rack:

TR_RACK_PATTERN=both TR_RACK_HEADON=both TR_RACK_LINEAR=both TR_RACK_TSETLIN=both \
TR_RACK_CIRCULAR=both TR_RACK_GUESSFACTOR=both TR_RACK_WALLBOUNCE=both \
TR_RACK_ACCEL=both TR_RACK_STOPSHOT=both TR_RACK_DISPLACE=both TR_RACK_AVGLEAD=both \
TR_RACK_DECAYGF=both TR_RACK_KNN=both TR_RACK_TMSELECT=both ./out/ModularBot

To force one gun alone: TR_RACK_PATTERN=off TR_RACK_TMHORIZON=both. If every gun is off, the rack falls back to admitting all of them.

2. The selector (virtual-bullet fitness)

variable	default	what it does
GUN_VBULLET_METRIC	path	how a virtual bullet is scored: path (swept ray — the better coarse signal, 7.4% vs 4.7% real) or point (arrival accuracy)
GUN_SELECTOR_MODE	relative	tie-band model: relative (scale-aware) or absolute (legacy fixed bars)
GUN_SELECTOR_WINDOW	100	rolling window (ticks) for the fitness rates
GUN_SELECTOR_TIE	0.20	tie band width: tied if rate >= bestRate*(1-this)
GUN_SELECTOR_DWELL	10	ticks the incumbent gun is held before it may be displaced
GUN_SELECTOR_MARGIN	0.05	a challenger must beat the incumbent by this fraction to displace it
GUN_SELECTOR_TIEBREAK	off	off (shipped) / point / pointCommit. Measured negative on real hit rate; opt-in only
GUN_SELECTOR_POINT_TIE	0.5	margin used by the point tie-break

Note: the per-tick random draw inside the tie band is load-bearing — replacing it with commitment to the virtual-best measurably lowered real hit rate (7.02% → 5.10%, p=0.002). Three attempts to "smarten" the band all failed.

3. Power policy (energy economy)

variable	default	what it does
TR_POWER_POLICY	1	0 = uncapped control arm. Measured: turning it off drops real hit rate 10.6%→7.9%
TR_POWER_FAR_DIST	200 px	beyond this = "bad chances zone"
TR_POWER_FAR_CAP	1.0	power cap beyond that distance
TR_POWER_MID_CAP	2.0	cap when close + healthy but chances are not above average
TR_POWER_REF	0.0	reference probability: 0 = the gun's own mean, >0 = a fixed threshold
TR_POWER_ENERGY_HI	80	at/above this energy, no energy-slope cap
TR_POWER_ENERGY_LO	20	at/below this energy, cap = ENERGY_MIN
TR_POWER_ENERGY_MIN	0.5	the cap at/below ENERGY_LO
TR_POWER_ENERGY_MAX	3.0	the cap at/above ENERGY_HI (3.0 = effectively uncapped)
TR_POWER_FINISH_KILL	1	cap power at the smallest bullet that can still kill the enemy
TR_POWER_LOG	off	1 = log each decision: [power] p=… cap=… reason=far|energySlope|finishKill|belowAvg|full|ram

WHY the slope: bullet speed is 20-3p, so lower power = faster bullet (less lead error, higher hit chance), fires more often (10+2p ticks) and drains energy more slowly (p/shot). E[dE] = p(3P-1), so break-even is 1/3 regardless of power — and our measured hit rates are 5–27%, far below it.

WHY the finishing cap: server 1.3.1 caps the damage score at the energy actually removed, so overkill scores nothing. Damage is 4p (p≤1) / 6p-2 (p>1), so the smallest killing power is E/4 for E≤4 and (E+2)/6 for 4<E≤16.

4. Movement

variable	default	what it does
TR_MOVEMENT	tfil	tfil (shipped) or tfil_ring (the range-weighted variant)
TR_MOVEMENT_LOG	off	1 = log band/range-class changes for the ring mover
TR_TFIL_RANGE_LO / _HI	100 / 200 px	the target-range band the ring mover prefers
TR_TFIL_RANGE_TEMP	0.4	peakiness of the range weighting. 0 = plain uniform draw = exact control
TR_TFIL_RANGE_K	60	softness of the falloff outside the band
TR_TFIL_CORRIDOR_HEAT	10.0	heat added along a bullet's corridor to the wall
TR_TFIL_WALL_HOTNESS	15.0	wall radiance

Ring mover is NOT the default and should not be shipped as-is: it had the best offline hit rate of anything measured, but it halves engagement range and halves survival (round wins 16/49 → 6/49, p=0.012) — a glass cannon.

5. Ramming

variable	default	what it does
TR_RAM_OPPORTUNITY	off	enable the proactive ram. Measured: converts 0/6 times — a straight-line pursuit cannot catch an equal-speed enemy
TR_RAM_OPP_DIST	200 px	opportunity trigger distance
TR_RAM_OPP_MARGIN	15	how much MORE energy we must have than the enemy
TR_RAM_ABORT_DMG	2.0	abort an in-progress ram above this incoming energy per turn (the "bullet rain" abort)
TR_RAM_PLAN	off	the speculative "change of plan" trigger
TR_RAM_PLAN_DIST / _MARGIN / _HITRATE	250 / 20 / 0.05	its thresholds
TR_RAM_LOG	off	1 = log [ram] ON/OFF with reason

The finisher ram (enemy <20 energy, we are healthier) is always on and is the only path that converts.

6. The horizon TM gun (TMHORIZON)

variable	default	what it does
TR_TMHORIZON_LOG	off	1 = per-shot thinking log + per-round summary
TR_TMHORIZON_SHIFT	2.0 deg	how far it may move the aim off Pattern's answer. 0 = predict but never move the aim (isolates prediction from application)
TR_TMHORIZON_BIG_MULT	1.5	multiplier when the predicted correction is BIG
TR_TMHORIZON_NSTATES	64	automata inertia — the "mood". Lower = adapts faster, higher = more stubborn (2…4096)
TR_TMHORIZON_RESET_ON_TARGET	on	wipe the model when the target changes (no-op in 1v1)
TR_TMHORIZON_WINDOW	0	sliding window: retrain on only the most recent N samples. 0 = keep everything
TR_TMHORIZON_RESET_DROP	0	change detection: if rolling accuracy falls this many points below its own peak, treat it as "the enemy changed" and re-learn
TR_TMHORIZON_ACCURVE	off	1 = log the rolling accuracy periodically
TR_TMHORIZON_RETRAIN_EVERY	50	samples between windowed retrains
TR_TMHORIZON_EPOCHS	1	epochs per windowed retrain

Learning persists across rounds of the same battle (so it can overfit the current enemy) and wipes only on a new battle or a target change. No learning is written to disk — nothing carries between battles.

7. Other gun knobs

variable	default	what it does
TR_PATTERN_RAD_OFFSET	0.0 px	shift Pattern's aim along its own bearing (negative = aim short)
TR_PATTERN_RAD_SCALE	1.0	multiplier on Pattern's aim distance

Both are structurally incapable of changing the shot — the live aim is bearing-only, so a purely radial offset is invisible. Measured byte-identical on bmPath. Kept for experiments; leave at defaults.

8. Measurement / instrumentation (all off by default, all zero-cost when off)

variable	default	what it does
TR_VBULLET_ADMIT_ONLY	1	only admitted guns spawn virtual bullets. Turning it on gave +68% tick rate (87→146 ticks/s); 0 restores the old behaviour
TR_RECORD_WORLDSTATE	off	append every tick's WorldState to /tmp/worldstate_record.jsonl for offline replay
TR_RADAR_FORCE_SPIN	off	force the old stateless full-spin melee radar (for A/B on one binary)
TR_RADAR_SCANLOG	off	append per-round radar scan/coverage JSON
TR_RADAR_SCAN_LOG_PATH	/tmp/radar_scan_log.jsonl	where that goes
TR_TRACKER_PROBE	off	per-tick enemy tracker vs server enemy count
TR_TRACKER_PROBE_PATH	/tmp/tracker_probe.jsonl	where that goes

9. Test harness only (not read by the bot itself)

variable	default	what it does
TR_SERVER_JAR	the 1.3.1 jar in ~/Downloads/robocode-tankroyale/	which server the tests launch. Set to the 0.35.5 jar to reproduce old numbers
TR_BATTLE_RUNNER	the 1.0.2 runner jar	which runner the tests launch
TR_BATTLE_RUNNER_DIR	derived	directory form of the runner

10. Compile-time knobs (-d: flags, need a rebuild)

flag	default	file
-d:TMH_NSTATES=N	64	guns/tm_horizon.nim — automata inertia (the runtime env overrides it)
-d:TMH_NCLAUSES=N	40	guns/tm_horizon.nim
-d:TMH_MIN_OBS=N	24	cold gate: below this many samples the TM emits no correction
-d:TMH_STALE_MAX=N	8	a sample is dropped if the enemy was not seen this recently
-d:TM_S_DEF=x	"3.0"	guns/tm_pattern.nim specificity (s). Higher = LONGER clauses, measured. s=1.0 is degenerate
-d:TM_NSTATES=N	64	guns/tm_pattern.nim

Adding / finding knobs

# everything the code reads
grep -rn 'TR_[A-Z_]*"' --include=*.nim ModularBot_garage/src common_libs | sort -u
# what a specific knob defaults to
grep -rn 'TR_POWER_ENERGY_MIN' --include=*.nim .

Convention followed throughout: read once at module init, into a let with an EnvVar name constant beside it, so one compiled binary can A/B every arm by environment alone.