Add PF2e weak/elite creature adjustments with stat block toggle

Weak/Normal/Elite toggle in PF2e stat block header applies standard
adjustments (level, AC, HP, saves, Perception, attacks, damage) to
individual combatants. Adjusted stats are highlighted blue (elite) or
red (weak). Persisted via creatureAdjustment field on Combatant.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

apps/web/src/hooks/use-encounter.ts

@@ -28,12 +28,15 @@ import type {
 	DomainError,
 	DomainEvent,
 	Encounter,
+	Pf2eCreature,
 	PlayerCharacter,
 	UndoRedoState,
 } from "@initiative/domain";
 import {
+	acDelta,
 	clearHistory,
 	combatantId,
+	hpDelta,
 	isDomainError,
 	creatureId as makeCreatureId,
 	pushUndo,
@@ -84,6 +87,12 @@ type EncounterAction =
 			entry: SearchResult;
 			count: number;
 	  }
+	| {
+			type: "set-creature-adjustment";
+			id: CombatantId;
+			adjustment: "weak" | "elite" | undefined;
+			baseCreature: Pf2eCreature;
+	  }
 	| { type: "add-from-player-character"; pc: PlayerCharacter }
 	| {
 			type: "import";
@@ -279,6 +288,76 @@ function handleAddFromPlayerCharacter(
 	};
 }
 
+function applyNamePrefix(
+	name: string,
+	oldAdj: "weak" | "elite" | undefined,
+	newAdj: "weak" | "elite" | undefined,
+): string {
+	let base = name;
+	if (oldAdj === "weak" && name.startsWith("Weak ")) base = name.slice(5);
+	else if (oldAdj === "elite" && name.startsWith("Elite "))
+		base = name.slice(6);
+	if (newAdj === "weak") return `Weak ${base}`;
+	if (newAdj === "elite") return `Elite ${base}`;
+	return base;
+}
+
+function handleSetCreatureAdjustment(
+	state: EncounterState,
+	id: CombatantId,
+	adjustment: "weak" | "elite" | undefined,
+	baseCreature: Pf2eCreature,
+): EncounterState {
+	const combatant = state.encounter.combatants.find((c) => c.id === id);
+	if (!combatant) return state;
+
+	const oldAdj = combatant.creatureAdjustment;
+	if (oldAdj === adjustment) return state;
+
+	const baseLevel = baseCreature.level;
+	const oldHpDelta = oldAdj ? hpDelta(baseLevel, oldAdj) : 0;
+	const newHpDelta = adjustment ? hpDelta(baseLevel, adjustment) : 0;
+	const netHpDelta = newHpDelta - oldHpDelta;
+
+	const oldAcDelta = oldAdj ? acDelta(oldAdj) : 0;
+	const newAcDelta = adjustment ? acDelta(adjustment) : 0;
+	const netAcDelta = newAcDelta - oldAcDelta;
+
+	const newMaxHp =
+		combatant.maxHp === undefined ? undefined : combatant.maxHp + netHpDelta;
+	const newCurrentHp =
+		combatant.currentHp === undefined || newMaxHp === undefined
+			? undefined
+			: Math.max(0, Math.min(combatant.currentHp + netHpDelta, newMaxHp));
+	const newAc =
+		combatant.ac === undefined ? undefined : combatant.ac + netAcDelta;
+	const newName = applyNamePrefix(combatant.name, oldAdj, adjustment);
+
+	const updatedCombatant: typeof combatant = {
+		...combatant,
+		name: newName,
+		...(newMaxHp !== undefined && { maxHp: newMaxHp }),
+		...(newCurrentHp !== undefined && { currentHp: newCurrentHp }),
+		...(newAc !== undefined && { ac: newAc }),
+		...(adjustment === undefined
+			? { creatureAdjustment: undefined }
+			: { creatureAdjustment: adjustment }),
+	};
+
+	const combatants = state.encounter.combatants.map((c) =>
+		c.id === id ? updatedCombatant : c,
+	);
+
+	return {
+		...state,
+		encounter: { ...state.encounter, combatants },
+		events: [
+			...state.events,
+			{ type: "CreatureAdjustmentSet", combatantId: id, adjustment },
+		],
+	};
+}
+
 // -- Reducer --
 
 export function encounterReducer(
@@ -310,6 +389,13 @@ export function encounterReducer(
 				lastCreatureId: null,
 			};
 		}
+		case "set-creature-adjustment":
+			return handleSetCreatureAdjustment(
+				state,
+				action.id,
+				action.adjustment,
+				action.baseCreature,
+			);
 		case "add-from-bestiary":
 			return handleAddFromBestiary(state, action.entry, 1);
 		case "add-multiple-from-bestiary":
@@ -565,6 +651,20 @@ export function useEncounter() {
 			(id: CombatantId) => dispatch({ type: "toggle-concentration", id }),
 			[],
 		),
+		setCreatureAdjustment: useCallback(
+			(
+				id: CombatantId,
+				adjustment: "weak" | "elite" | undefined,
+				baseCreature: Pf2eCreature,
+			) =>
+				dispatch({
+					type: "set-creature-adjustment",
+					id,
+					adjustment,
+					baseCreature,
+				}),
+			[],
+		),
 		clearEncounter: useCallback(
 			() => dispatch({ type: "clear-encounter" }),
 			[],