Add encounter difficulty indicator (5.5e XP budget)

Live 3-bar difficulty indicator in the top bar showing encounter
difficulty (Trivial/Low/Moderate/High) based on the 2024 5.5e XP
budget system. Automatically derived from PC levels and bestiary
creature CRs.

- Add optional level field (1-20) to PlayerCharacter
- Add CR-to-XP and XP Budget per Character lookup tables in domain
- Add calculateEncounterDifficulty pure function
- Add DifficultyIndicator component with color-coded bars and tooltip
- Add useDifficulty hook composing encounter, PC, and bestiary contexts
- Indicator hidden when no PCs with levels or no bestiary-linked monsters
- Level field in PC create/edit forms, persisted in storage

Closes #18

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

apps/web/src/components/__tests__/turn-navigation.test.tsx

@@ -6,11 +6,19 @@ import { combatantId } from "@initiative/domain";
 import { cleanup, render, screen } from "@testing-library/react";
 import { afterEach, describe, expect, it, vi } from "vitest";
 
-// Mock the context module
+// Mock the context modules
 vi.mock("../../contexts/encounter-context.js", () => ({
 	useEncounterContext: vi.fn(),
 }));
 
+vi.mock("../../contexts/player-characters-context.js", () => ({
+	usePlayerCharactersContext: vi.fn().mockReturnValue({ characters: [] }),
+}));
+
+vi.mock("../../contexts/bestiary-context.js", () => ({
+	useBestiaryContext: vi.fn().mockReturnValue({ getCreature: () => undefined }),
+}));
+
 import { useEncounterContext } from "../../contexts/encounter-context.js";
 import { TurnNavigation } from "../turn-navigation.js";
 

apps/web/src/components/create-player-modal.tsx

@@ -7,6 +7,13 @@ import { Button } from "./ui/button";
 import { Dialog } from "./ui/dialog";
 import { Input } from "./ui/input";
 
+function parseLevel(value: string): number | undefined | "invalid" {
+	if (value.trim() === "") return undefined;
+	const n = Number.parseInt(value, 10);
+	if (Number.isNaN(n) || n < 1 || n > 20) return "invalid";
+	return n;
+}
+
 interface CreatePlayerModalProps {
 	open: boolean;
 	onClose: () => void;
@@ -16,6 +23,7 @@ interface CreatePlayerModalProps {
 		maxHp: number,
 		color: string | undefined,
 		icon: string | undefined,
+		level: number | undefined,
 	) => void;
 	playerCharacter?: PlayerCharacter;
 }
@@ -31,6 +39,7 @@ export function CreatePlayerModal({
 	const [maxHp, setMaxHp] = useState("10");
 	const [color, setColor] = useState("blue");
 	const [icon, setIcon] = useState("sword");
+	const [level, setLevel] = useState("");
 	const [error, setError] = useState("");
 
 	const isEdit = !!playerCharacter;
@@ -43,12 +52,18 @@ export function CreatePlayerModal({
 				setMaxHp(String(playerCharacter.maxHp));
 				setColor(playerCharacter.color ?? "");
 				setIcon(playerCharacter.icon ?? "");
+				setLevel(
+					playerCharacter.level === undefined
+						? ""
+						: String(playerCharacter.level),
+				);
 			} else {
 				setName("");
 				setAc("10");
 				setMaxHp("10");
 				setColor("");
 				setIcon("");
+				setLevel("");
 			}
 			setError("");
 		}
@@ -71,7 +86,19 @@ export function CreatePlayerModal({
 			setError("Max HP must be at least 1");
 			return;
 		}
-		onSave(trimmed, acNum, hpNum, color || undefined, icon || undefined);
+		const levelNum = parseLevel(level);
+		if (levelNum === "invalid") {
+			setError("Level must be between 1 and 20");
+			return;
+		}
+		onSave(
+			trimmed,
+			acNum,
+			hpNum,
+			color || undefined,
+			icon || undefined,
+			levelNum,
+		);
 		onClose();
 	};
 
@@ -135,6 +162,20 @@ export function CreatePlayerModal({
 							className="text-center"
 						/>
 					</div>
+					<div className="flex-1">
+						<span className="mb-1 block text-muted-foreground text-sm">
+							Level
+						</span>
+						<Input
+							type="text"
+							inputMode="numeric"
+							value={level}
+							onChange={(e) => setLevel(e.target.value)}
+							placeholder="1-20"
+							aria-label="Level"
+							className="text-center"
+						/>
+					</div>
 				</div>
 
 				<div>

apps/web/src/components/difficulty-indicator.tsx

@@ -0,0 +1,39 @@
+import type { DifficultyResult, DifficultyTier } from "@initiative/domain";
+import { cn } from "../lib/utils.js";
+
+const TIER_CONFIG: Record<
+	DifficultyTier,
+	{ filledBars: number; color: string; label: string }
+> = {
+	trivial: { filledBars: 0, color: "", label: "Trivial" },
+	low: { filledBars: 1, color: "bg-green-500", label: "Low" },
+	moderate: { filledBars: 2, color: "bg-yellow-500", label: "Moderate" },
+	high: { filledBars: 3, color: "bg-red-500", label: "High" },
+};
+
+const BAR_HEIGHTS = ["h-2", "h-3", "h-4"] as const;
+
+export function DifficultyIndicator({ result }: { result: DifficultyResult }) {
+	const config = TIER_CONFIG[result.tier];
+	const tooltip = `${config.label} encounter difficulty`;
+
+	return (
+		<div
+			className="flex items-end gap-0.5"
+			title={tooltip}
+			role="img"
+			aria-label={tooltip}
+		>
+			{BAR_HEIGHTS.map((height, i) => (
+				<div
+					key={height}
+					className={cn(
+						"w-1 rounded-sm",
+						height,
+						i < config.filledBars ? config.color : "bg-muted",
+					)}
+				/>
+			))}
+		</div>
+	);
+}

apps/web/src/components/player-character-section.tsx

@@ -35,7 +35,7 @@ export const PlayerCharacterSection = function PlayerCharacterSectionInner({
 					setEditingPlayer(undefined);
 					setManagementOpen(true);
 				}}
-				onSave={(name, ac, maxHp, color, icon) => {
+				onSave={(name, ac, maxHp, color, icon, level) => {
 					if (editingPlayer) {
 						editCharacter(editingPlayer.id, {
 							name,
@@ -43,9 +43,10 @@ export const PlayerCharacterSection = function PlayerCharacterSectionInner({
 							maxHp,
 							color: color ?? null,
 							icon: icon ?? null,
+							level: level ?? null,
 						});
 					} else {
-						createCharacter(name, ac, maxHp, color, icon);
+						createCharacter(name, ac, maxHp, color, icon, level);
 					}
 				}}
 				playerCharacter={editingPlayer}

apps/web/src/components/player-management.tsx

@@ -68,6 +68,11 @@ export function PlayerManagement({
 								<span className="text-muted-foreground text-xs tabular-nums">
 									HP {pc.maxHp}
 								</span>
+								{pc.level !== undefined && (
+									<span className="text-muted-foreground text-xs tabular-nums">
+										Lv {pc.level}
+									</span>
+								)}
 								<Button
 									variant="ghost"
 									size="icon-sm"

apps/web/src/components/turn-navigation.tsx

@@ -1,5 +1,7 @@
 import { Redo2, StepBack, StepForward, Trash2, Undo2 } from "lucide-react";
 import { useEncounterContext } from "../contexts/encounter-context.js";
+import { useDifficulty } from "../hooks/use-difficulty.js";
+import { DifficultyIndicator } from "./difficulty-indicator.js";
 import { Button } from "./ui/button.js";
 import { ConfirmButton } from "./ui/confirm-button.js";
 
@@ -15,6 +17,7 @@ export function TurnNavigation() {
 		canRedo,
 	} = useEncounterContext();
 
+	const difficulty = useDifficulty();
 	const hasCombatants = encounter.combatants.length > 0;
 	const isAtStart = encounter.roundNumber === 1 && encounter.activeIndex === 0;
 	const activeCombatant = encounter.combatants[encounter.activeIndex];
@@ -66,6 +69,7 @@ export function TurnNavigation() {
 				) : (
 					<span className="text-muted-foreground">No combatants</span>
 				)}
+				{difficulty && <DifficultyIndicator result={difficulty} />}
 			</div>
 
 			<div className="flex flex-shrink-0 items-center gap-3">