Implement center-weighted energy distribution as a forcing function
to pull players into contested midfield, increasing combat density.
Changes:
- engine/match.go: Update placeEnergyNodes to use tiered radius
distribution (30% central 0.05-0.20, 40% mid 0.20-0.40, 30% outer
0.40-0.60) instead of uniform 0.3-0.7
- engine/integration_test.go: Add TestIntegration_CenterWeightedEnergy
to verify ~25% of energy nodes spawn in central zone
- cmd/acb-mapgen: Already had tiered distribution (unchanged, just
comments updated)
- cmd/acb-mapgen/mapgen_test.go: Add TestGenerateMap_CenterWeightedEnergy
This uses the existing economic incentive (energy collection) as a
forcing function without changing combat resolution or scoring.
Closes: bf-648i
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>