Entry 67

piney-battle: the rules of combat, the enemies' and party's decisions and items, checked against the game

2026-09-23battletest

Filescrates/piney-battletools/test_battle_rs.pytools/test_battle_flow_rs.pytools/test_battle_drain_rs.pytools/test_battle_items_rs.pytools/test_battle_enemy_ai_rs.pytools/test_battle_party_ai_rs.pydocs/engine/battle.md

The goal needs the opening's fights. 22 and 25 had worked out Infection's battle formulas in Python (tools/battle.py). A battle agent and three helpers have now ported the rules half of combat to Rust as a pure-logic crate, piney-battle (about 14,000 lines). It has no drawing, animation or movement: those are the runtime's.

What it holds

• The formulas.
  • CalcReal;
  • CalcBattleDamage with the protect gauge and Exdefense;
  • ccSkillDamage's four forms and ccSkillDamageValue;
  • recovery, cures, hold and condition changes;
  • experience, levels and erosion;
  • EntryAffect with each kind of character's affectFunc.
• A skill's life. _ccSkillRequest through ccSkill::Main (ccThSkill) with its systems, NoteEventAffect, and the player's and fellows' attack notes.
• Data Drain. DataDrainMenu's steps: the drain, the side effect and level down, and evolution.
• Items. All of useitem.cpp and the save's item lists.
• The enemies' decisions. enemy.cpp's think, attack, skill and target choices, and genrand (the enemies' own MT19937).
• The party's decisions. ccAI: Brains, Reconnoiter, ActInField, ActInDungeon, healing, attack choice, chat commands, and its message bus.
• The shape. Each rule returns events in the game's call order. A Scene stands for the three command lists; Rand is newlib's rand() and Genrand the enemies' generator.

Bugs found while merging

• _ccSkillCheckType had 1 and -2 swapped: 1 is an attack spell, -2 a debuff.
• ccSkillDamageValue takes both characters' list checks.
• A cure cast on oneself lost its SP change.
• ConditionAdjustment does not run every frame.

Checked

• Against the game. Six harnesses run the game's functions natively in eemu beside the port. Each compares the return value, every character and AI field, both generators' states, and the calls in order. There are 125 checks, each over at least 1,000 random cases, with 0 mismatches. The core, flow and drain checks also passed 10,000 cases each.

  harness	covers
  test_battle_rs.py	damage, skills' effects, stats, levels, conditions, experience, erosion, EntryAffect
  test_battle_flow_rs.py	ccSkill::Main, notes, ccSkillCheck, ConditionAdjustment, level ups, AreaItem
  test_battle_drain_rs.py	DataDrainMenu steps 0-1, 10, 20
  test_battle_items_rs.py	useitem.cpp and the item lists
  test_battle_enemy_ai_rs.py	enemy.cpp's decisions, genrand
  test_battle_party_ai_rs.py	ccAI and its message bus

• Re-run in a clean worktree. I re-ran all six there, with the older test_battle.py: all pass. The workspace's tests pass, and clippy, fmt and the docs check are clean.