Fix PF2e rules math: AC proficiency, weapon damage, MAP, striking, slots, Refocus

Confirmed accuracy defects from the audit:
- AC now scales with level + armor proficiency (10 + Dex + (level+rank) + item),
  defaulting to trained; was 10 + Dex only, wrong by +3..+28.
- Weapon potency (itemBonus) applies to the attack roll ONLY, not flat damage.
- weaponAttack now reports the Multiple Attack Penalty (-5/-10, agile -4/-8) and
  expands striking runes into extra weapon dice; AttacksSection surfaces MAP.
- Full-caster spell slots: 2 at the rank's unlock level, 3 thereafter (was a flat 3,
  giving a level-1 caster 3 first-rank slots instead of 2).
- PF2e Refocus restores one Focus Point (recoverStep), not the whole pool.

Adds 6 regression tests. types.ts gains WeaponInput.agile/striking, WeaponResult.map,
CharacterRulesInput.acRank, RestOption.recoverStep.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/lib/rules/pf2e/index.ts

@@ -11,9 +11,9 @@ import { ABILITY_LABELS, abilityModifier, defaultAbilityScores, formatDamage } f
 import { PF2E_SKILLS } from './skills';
 
 const PF2E_RESTS: readonly RestOption[] = [
-  // Refocus restores 1 Focus Point (short-recovery resources).
-  { id: 'refocus', label: 'Refocus', restoresHp: false, restoresSlots: false, restoresPact: false, recovers: ['short'] },
-  // A full night's rest restores HP, spell slots, and daily resources.
+  // Refocus restores exactly ONE Focus Point (recoverStep: 1), not the whole pool.
+  { id: 'refocus', label: 'Refocus', restoresHp: false, restoresSlots: false, restoresPact: false, recovers: ['short'], recoverStep: 1 },
+  // A full night's rest restores HP, spell slots, and daily resources (to max).
   { id: 'rest', label: 'Rest for the Night', restoresHp: true, restoresSlots: true, restoresPact: true, recovers: ['long', 'daily'] },
 ];
 
@@ -35,6 +35,17 @@ export function pf2eProficiency(level: number, rank: ProficiencyRank): number {
   return lvl + RANK_BONUS[rank];
 }
 
+/**
+ * Apply a striking rune to a weapon's damage dice by multiplying the dice COUNT
+ * (striking = 2×, greater = 3×, major = 4×). "1d8" + striking(2) -> "2d8". Leaves
+ * non-"NdM" expressions and the no-rune case untouched.
+ */
+export function expandStriking(dice: string | undefined, striking?: number): string | undefined {
+  const mult = striking && striking > 1 ? Math.floor(striking) : 1;
+  if (mult === 1 || !dice) return dice;
+  return dice.replace(/(\d+)d(\d+)/gi, (_m, n: string, faces: string) => `${Number(n) * mult}d${faces}`);
+}
+
 export const pf2e: RulesSystem = {
   id: 'pf2e',
   label: 'Pathfinder 2e',
@@ -78,12 +89,15 @@ export const pf2e: RulesSystem = {
   baseArmorClass(input) {
     const dex = abilityModifier(input.abilities.dex);
     const misc = input.armorBonus ?? 0;
+    // PF2e AC scales with level: 10 + Dex(capped) + proficiency(level + rank) + item.
+    // `armorBonus` now carries only true item/circumstance bonuses (e.g. a shield).
+    const prof = pf2eProficiency(input.level, input.acRank ?? 'trained');
     if (input.equippedArmor) {
       const { baseAc, dexCap } = input.equippedArmor;
-      return baseAc + (dexCap === null ? dex : Math.min(dex, dexCap)) + misc;
+      // baseAc embeds the armor's flat AC (10 + armor item bonus); add Dex + prof + misc.
+      return baseAc + (dexCap === null ? dex : Math.min(dex, dexCap)) + prof + misc;
     }
-    // 10 + dex + (item/proficiency folded into armorBonus for the MVP sheet).
-    return 10 + dex + misc;
+    return 10 + dex + prof + misc;
   },
 
   spellSaveDc(input, ability) {
@@ -101,9 +115,18 @@ export const pf2e: RulesSystem = {
   weaponAttack(input, weapon) {
     const abilityMod = abilityModifier(input.abilities[weapon.ability]);
     const item = weapon.itemBonus ?? 0;
+    // Potency (itemBonus) applies to the attack roll only — never a flat damage bonus.
     const toHit = abilityMod + pf2eProficiency(input.level, weapon.rank) + item;
-    const dmgMod = (weapon.addAbilityToDamage !== false ? abilityMod : 0) + item;
-    return { toHit, damage: formatDamage(weapon.damageDice, dmgMod) };
+    const dmgMod = weapon.addAbilityToDamage !== false ? abilityMod : 0;
+    // Striking runes add weapon dice (2/3/4×), they do not add a flat bonus.
+    const dice = expandStriking(weapon.damageDice, weapon.striking);
+    // Multiple Attack Penalty: -5/-10, or -4/-8 with an agile weapon.
+    const penalty = weapon.agile ? 4 : 5;
+    return {
+      toHit,
+      damage: formatDamage(dice, dmgMod),
+      map: { second: toHit - penalty, third: toHit - penalty * 2 },
+    };
   },
 
   carryingCapacity(input) {

src/lib/rules/pf2e/progression.ts

@@ -53,9 +53,10 @@ export function pf2eHp(classHp: number, level: number, conMod: number, ancestryH
 }
 
 /**
- * Spell slots per rank for a full caster. A new rank unlocks at each odd level;
- * each available rank gets 3 slots (the standard for prepared/spontaneous casters).
- * Approximate and editable on the sheet.
+ * Spell slots per rank for a full caster. A new rank unlocks at each odd level
+ * (rank r at level 2r-1); a rank holds 2 slots on the level it unlocks and 3 from
+ * the next level on (e.g. a level-1 caster has 2 first-rank slots, not 3). The
+ * 10th-rank slot is a single capstone slot. Approximate and editable on the sheet.
  */
 export function pf2eSlots(caster: ClassDef['caster'], level: number): { level: number; max: number; current: number }[] {
   if (caster !== 'full') return [];
@@ -63,7 +64,8 @@ export function pf2eSlots(caster: ClassDef['caster'], level: number): { level: n
   const topRank = Math.min(10, Math.ceil(lvl / 2));
   const slots: { level: number; max: number; current: number }[] = [];
   for (let r = 1; r <= topRank; r++) {
-    const max = r === 10 ? 1 : 3;
+    const unlockLevel = 2 * r - 1;
+    const max = r === 10 ? 1 : lvl <= unlockLevel ? 2 : 3;
     slots.push({ level: r, max, current: max });
   }
   return slots;

src/lib/rules/rest.ts

@@ -18,10 +18,14 @@ export function applyRest(c: Character, opt: RestOption): Partial<Character> {
   // Any rest ends ongoing concentration (you stop holding the spell to rest).
   if (c.concentration) patch.concentration = null;
 
-  // Resources refresh when their recovery tag is covered by this rest.
-  patch.resources = c.resources.map((r) =>
-    opt.recovers.includes(r.recovery) ? { ...r, current: r.max } : r,
-  );
+  // Resources refresh when their recovery tag is covered by this rest. A rest with
+  // `recoverStep` (PF2e Refocus) restores by that step, clamped to max, rather than
+  // refilling the whole pool — so Refocus returns one Focus Point, not all of them.
+  patch.resources = c.resources.map((r) => {
+    if (!opt.recovers.includes(r.recovery)) return r;
+    const next = opt.recoverStep !== undefined ? Math.min(r.max, r.current + opt.recoverStep) : r.max;
+    return { ...r, current: next };
+  });
 
   if (opt.restoresSlots || opt.restoresPact) {
     patch.spellcasting = {

src/lib/rules/rules.test.ts

@@ -2,6 +2,8 @@ import { describe, it, expect } from 'vitest';
 import { abilityModifier } from './abilities';
 import { dnd5e, proficiencyBonus } from './dnd5e';
 import { pf2e, pf2eProficiency } from './pf2e';
+import { pf2eSlots } from './pf2e/progression';
+import { applyRest } from './rest';
 import type { CharacterRulesInput } from './types';
 
 describe('abilityModifier', () => {
@@ -100,4 +102,59 @@ describe('pf2e proficiency', () => {
     expect(saves.dex).toBe(2 + (4 + 2));
     expect(saves.str).toBe(0); // not a save: just ability mod
   });
+
+  it('AC scales with level + armor proficiency (not just 10 + Dex)', () => {
+    // level-5 fighter, Dex +1, trained in defense, unarmored: 10 + 1 + (5 + 2) = 18
+    const ac = pf2e.baseArmorClass({
+      level: 5,
+      abilities: { str: 18, dex: 12, con: 14, int: 10, wis: 12, cha: 10 },
+      acRank: 'trained',
+    });
+    expect(ac).toBe(18);
+  });
+
+  it('weapon attack: potency adds to-hit only, never flat damage', () => {
+    // level-3, STR 18 (+4), trained (3+2=+5), +1 potency, 1d8
+    const r = pf2e.weaponAttack(
+      { level: 3, abilities: { str: 18, dex: 10, con: 10, int: 10, wis: 10, cha: 10 } },
+      { ability: 'str', rank: 'trained', itemBonus: 1, damageDice: '1d8' },
+    );
+    expect(r.toHit).toBe(4 + 5 + 1); // +10
+    expect(r.damage).toBe('1d8+4'); // STR only — no +item on damage
+  });
+
+  it('weapon attack reports MAP (-5/-10, agile -4/-8) and striking dice', () => {
+    const base = { level: 3, abilities: { str: 18, dex: 10, con: 10, int: 10, wis: 10, cha: 10 } };
+    const sword = pf2e.weaponAttack(base, { ability: 'str', rank: 'trained', damageDice: '1d8', striking: 2 });
+    expect(sword.toHit).toBe(9);
+    expect(sword.map).toEqual({ second: 4, third: -1 }); // -5 / -10
+    expect(sword.damage).toBe('2d8+4'); // striking doubles the dice
+    const agile = pf2e.weaponAttack(base, { ability: 'str', rank: 'trained', damageDice: '1d6', agile: true });
+    expect(agile.map).toEqual({ second: 5, third: 1 }); // -4 / -8
+  });
+
+  it('full caster has 2 first-rank slots at level 1, 3 from level 2', () => {
+    expect(pf2eSlots('full', 1)).toEqual([{ level: 1, max: 2, current: 2 }]);
+    expect(pf2eSlots('full', 2)).toEqual([{ level: 1, max: 3, current: 3 }]);
+    // level 3: 3 first-rank + 2 (newly unlocked) second-rank
+    expect(pf2eSlots('full', 3)).toEqual([
+      { level: 1, max: 3, current: 3 },
+      { level: 2, max: 2, current: 2 },
+    ]);
+  });
+});
+
+describe('pf2e Refocus', () => {
+  it('restores one Focus Point, not the whole pool', () => {
+    const refocus = pf2e.restOptions.find((o) => o.id === 'refocus')!;
+    const c = {
+      resources: [{ id: 'f', name: 'Focus Points', current: 0, max: 3, recovery: 'short' as const }],
+      hp: { current: 10, max: 10, temp: 0 },
+      concentration: null,
+      spellcasting: { slots: [], spells: [] },
+      defenses: { exhaustion: 0, deathSaves: { successes: 0, failures: 0 } },
+    } as unknown as Parameters<typeof applyRest>[0];
+    const patch = applyRest(c, refocus);
+    expect(patch.resources?.[0]?.current).toBe(1); // +1, clamped to max — not 3
+  });
 });

src/lib/rules/types.ts

@@ -27,18 +27,31 @@ export interface WeaponInput {
   ability: AbilityKey;
   /** proficiency in the weapon */
   rank: ProficiencyRank;
-  /** flat magic/enhancement bonus to hit and damage */
+  /**
+   * Flat magic/enhancement bonus. In 5e this applies to BOTH to-hit and damage.
+   * In PF2e this is a weapon potency rune — it applies to the attack roll ONLY,
+   * never to a flat damage bonus (extra magic-weapon damage comes from `striking`).
+   */
   itemBonus?: number;
   /** damage dice, e.g. "1d8" */
   damageDice?: string;
   /** add the ability modifier to damage (off-hand/some ranged turn this off) */
   addAbilityToDamage?: boolean;
+  /** PF2e: the agile trait lowers the multiple-attack penalty to -4/-8. */
+  agile?: boolean;
+  /** PF2e striking-rune tier as a damage-dice multiplier: 2=striking, 3=greater, 4=major. 1/undefined = none. */
+  striking?: number;
 }
 
 export interface WeaponResult {
   toHit: number;
   /** ready-to-roll damage expression, e.g. "1d8+3" */
   damage: string;
+  /**
+   * PF2e multiple-attack penalty: the to-hit for the 2nd and 3rd+ attack actions
+   * this turn (-5/-10, or -4/-8 with an agile weapon). Absent for 5e.
+   */
+  map?: { second: number; third: number };
 }
 
 export interface CarryingCapacity {
@@ -59,6 +72,12 @@ export interface RestOption {
   /** resource.recovery tags that refresh */
   recovers: readonly Recovery[];
   reduceExhaustion?: boolean;
+  /**
+   * How much of a matched resource this rest restores. Omitted/undefined = restore
+   * to max (5e short/long rest). A number restores by that step, clamped to max —
+   * PF2e Refocus uses `1` (one Focus Point), not the whole pool.
+   */
+  recoverStep?: number;
 }
 
 export type Recovery = 'short' | 'long' | 'daily' | 'none';
@@ -134,4 +153,10 @@ export interface CharacterRulesInput {
   perceptionRank?: ProficiencyRank;
   /** PF2e: spellcasting proficiency. */
   spellcastingRank?: ProficiencyRank;
+  /**
+   * PF2e: armor/unarmored-defense proficiency. PF2e AC scales with level via this
+   * rank (10 + Dex + (level + rankBonus) + item). Missing = trained (the common
+   * level-1 case). Ignored by 5e, whose AC has no proficiency term.
+   */
+  acRank?: ProficiencyRank;
 }